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Sample records for resin significantly degrades

  1. Subsurface degradation of resin-based composites.

    Science.gov (United States)

    Bagheri, Rafat; Tyas, Martin J; Burrow, Michael F

    2007-08-01

    To determine the depth of a degraded subsurface layer produced in dental composites as a result of exposure to lactic acid or NaOH, by observing the penetration of AgNO(3) solution. Specimens were prepared from four resin composites; Point 4 (Kerr), Premise (Kerr), Filtek Supreme (3M/ESPE), Ceram X (Dentsply), and two polyacid-modified resin composites; Dyract (Dentsply) and F2000 (3M/ESPE). The specimens were immersed in distilled water for 1 week, transferred to one of three aqueous media at 60 degrees C for 2 weeks; distilled water, 0.01mol/L lactic acid or 0.1N NaOH, washed and immersed in 50% (w/w) aqueous silver nitrate for 10 days at 60 degrees C and placed in a photodeveloper solution. After reduction of the silver, specimens were embedded in epoxy resin, sectioned and polished, coated with carbon, and examined by backscattered mode scanning electron microscopy. The depth of silver penetration into the degraded area was measured from the SEM micrographs. Energy dispersive analysis X-ray (EDAX) was used to confirm the presence of silver. NaOH produced the greatest depth of degradation and lactic acid the least. Premise showed the greatest depth of silver penetration when subjected to NaOH, and Filtek Supreme the second with peeling of the surface and cracking, whereas F2000 and Point 4 showed the least in NaOH and lactic acid. ANOVA and Tukey's test showed that the depth of silver penetration was material and solution dependent, and the differences were significant for most of the materials (P<0.05).

  2. Microbial degradation of resins fractionated from Arabian light crude oil

    International Nuclear Information System (INIS)

    Venkateswaran, K.; Hoaki, T.; Kato, M.; Maruyama, T.

    1995-01-01

    Sediment samples from the Japanese coasts were screened for microorganisms able to degrade resin components of crude oil. A mixed population that could degrade 35% of 5000 ppm resin in 15 days was obtained. This population also metabolized 50% of saturates and aromatics present in crude oil (5000 ppm) in 7 days. A Pseudomonas sp., isolated from the mixed population, emulsified and degraded 30% of resins. It also degraded saturates and aromatics (30%) present in crude oil (5000 ppm). These results were obtained from Iatroscan analysis. Degradation of crude oil was also analyzed by gas chromatography (GC). The peaks corresponding to known aliphatic hydrocarbons in crude oil greatly decreased within the first two days of incubation in the cultures of the RY-mixed population and of Pseudomonas strain UN3. Aromatic compounds detected as a broad peak by GC were significantly degraded at day 7 by Pseudomonas strain UN3, and at day 15 by the RY-mixed population. Investigations are ongoing to determine the genetic basis for the ability of these organisms to grow on the resin fractions of crude oil as a sole source of carbon and energy. 28 refs., 4 figs., 1 tab

  3. Benzoxazine resin/carbon nanotube nanostructured composite's degradation kinetic.

    Science.gov (United States)

    Untem, Flávia O; Botelho, Edson C; Rezende, Mirabel C; Costa, Michelle Leali

    2014-07-01

    In the last decades a new class of thermoset phenolic resin is emerging as a substitute of the traditional epoxy and phenolic resins in the aircraft industry. This new class is called polybenzoxazines and its associates the epoxy resin's mechanical properties and phenolic resin's thermal and flame retardant properties, resulting in a resin with superior properties when analyzed with the others singly. The introduction of carbon nanotubes in low concentration into polymeric matrices can produce nanostructured materials with good properties. Thus, in this study, nanostructured composites of benzoxazine resin were processed with different concentration of carbon nanotubes (0.1%, 0.5% and 1.0% w/w). In order to evaluate the thermostability of the benzoxazine resin and its nanostructured composites, it was performed a degradation kinetic study using the thermogravimetric technique. For that, the analysis have been done with the temperature ranging from 25 degrees C to 1000 degrees C at nitrogen atmosphere (100 mL x min(-1)) and in different heating rates (2, 4, 6, 8, 10 and 20 degrees C x min(-1)), in order to obtain the kinetic parameters (activation energy, E(a), and pre-exponential factor, A), based on Ozawa-Wall-Flynn model. The results showed excellent agreement between the thermogravimetric curves obtained and the Ozawa-Wall-Flynn method. The degradation kinetic study showed that the introduction of carbon nanotubes in the benzoxazine matrix does not change the thermostability of the resin, so that it does not have a significant influence in the shelf life of the material.

  4. Determination of degradation conditions of exchange resins containing technetium

    International Nuclear Information System (INIS)

    Rivera S, A.; Monroy G, F.; Quintero P, E.

    2014-10-01

    The quantification of Tc-99 in spent exchange resins, coming from nuclear power plants, is indispensable to define their administration. The Tc-99 is a pure beta emitter of 210000 years of half-life, volatile and of a high mobility in water and soil. For this reason, the objective of this work is to establish a digestion method of ionic exchange resins containing technetium that retains more than 95% of this radioisotope. Mineralization tests were carried out of a resin Amberlite IRN-150 by means of an oxidation heat, in acid medium, varying the resin mass, the medium volume, the media type, the temperature and the digestion time. The digested samples were analyzed by gas chromatography to estimate the grade of their degradation. The 99m Tc was used as tracer to determine the technetium percentage recovered after mineralizing the resin. The digestion process depends on the temperature and the resin mass. At higher temperature better mineralization of samples and to greater resin mass to a constant temperature, less degradation of the resin. The spectra beta of the 99m Tc and 99 Tc are presented. (Author)

  5. Degradation, Fatigue, and Failure of Resin Dental Composite Materials

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, J.L. (UIC)

    2008-11-03

    The intent of this article is to review the numerous factors that affect the mechanical properties of particle- or fiber-filler-containing indirect dental resin composite materials. The focus will be on the effects of degradation due to aging in different media, mainly water and water and ethanol, cyclic loading, and mixed-mode loading on flexure strength and fracture toughness. Several selected papers will be examined in detail with respect to mixed and cyclic loading, and 3D tomography with multi-axial compression specimens. The main cause of failure, for most dental resin composites, is the breakdown of the resin matrix and/or the interface between the filler and the resin matrix. In clinical studies, it appears that failure in the first 5 years is a restoration issue (technique or material selection); after that time period, failure most often results from secondary decay.

  6. Degradation of ion spent resin using the Fenton's reagent

    International Nuclear Information System (INIS)

    Araujo, Leandro Goulart de

    2013-01-01

    The most common method for spent radioactive ion exchange resin treatment is its immobilization in cement, which reduces the radionuclides release into the environment. Although this method is efficient, it increases considerably the final volume of the waste due to the low incorporation capacity. The objective of this work was to develop a degradation method of spent resins arising from the nuclear research reactor located at the Nuclear and Energy Research Institute (IPEN-CNEN/SP), using an Advanced Oxidation Process (AOP) with Fenton's reagents. This method would allow a higher incorporation in cement. Three different resins were evaluated: cationic, anionic and a mixture of both resins. The reactions were conducted varying the catalyst concentration (25, 50, 100 and 150 mM), the volume of hydrogen peroxide (320 to 460 mL), and three different temperatures, 50, 60 and 70 deg C. Degradation of about 98% was achieved using a 50 mM catalyst solution and 330 mL of hydrogen peroxide solution. The most efficient temperature was 60 deg C. (author)

  7. Evaluation of Degradation in Nanofilled Adhesive Resins Using Quantitative Light-Induced Fluorescence

    Directory of Open Access Journals (Sweden)

    Tae-Young Park

    2014-01-01

    Full Text Available The aim of this study was to evaluate degradation in commercial dental nanofilled adhesive resins using quantitative light-induced fluorescence (QLF. Three adhesives were selected: D/E resin (DR, Single Bond Plus (SB, and G-Bond (GB. The adhesives were mixed with porphyrin for the QLF analysis. Specimens were prepared by dispensing blended adhesives into a flexible mold and polymerizing. Then, the QLF analysis of the specimens was done and the porphyrin values (Simple Plaque Score and ΔR were measured. After thermocycling of the specimens (5000 cycles, 5 to 55°C for the degradation, the specimens were assayed by QLF again. The porphyrin values were analyzed using paired t-test at a 95% confidence level. A significant reduction in SPS was observed in all groups after thermocycling. The ΔR significantly decreased after thermocycling except area ΔR30 of SB group. Overall, porphyrin values decreased after thermocycling which indicates that the degradation of the adhesive resins may be measured by the change of porphyrin value. The QLF method could be used to evaluate the degradation of adhesive resin.

  8. EPICOR-II resin characterization and proposed methods for degradation analysis. Rev. 1

    International Nuclear Information System (INIS)

    Doyle, J.D.; McConnell, J.W. Jr.; Sanders, R.D. Sr.

    1984-06-01

    One goal of the EPICOR-II Research and Disposition Program is the examination of the EPICOR-II organic ion-exchange resins for physical and chemical degradation. This report summarizes preliminary information necessary for the evaluation of the resins for degradation. Degradation of the synthetic organic ion-exchange resins should be efficiently and accurately measurable by using the baseline data provided by the nonirradiated resin characterization. The degradation threshold is about 10 8 rads, approximately the same dose rate the resins will have received by the examination date. If degradation has not occurred at the first examination point, later examinations will detect resin degradation using the same analytical methods. The results from the characterization tests will yield practical and useful data on the actual effects of radiation on commercial synthetic organic ion-exchange resins. 10 references, 12 figures

  9. Thermal degradation kinetics and antimicrobial studies of terpolymer resins

    Directory of Open Access Journals (Sweden)

    Abdul R. Burkanudeen

    2016-09-01

    Full Text Available The terpolymer (ASF was synthesized by condensation of anthranilic acid and salicylic acid with formaldehyde in the presence of glacial acetic acid as a catalyst at 140 ± 2 °C for 6 h with varying proportions of reactants. The terpolymer ASF-I was characterized by elemental analysis, FTIR, 1H NMR and 13C NMR spectroscopy. The thermal decomposition behavior of ASF-I, II and III terpolymers was studied using thermogravimetric analysis (TGA in a static nitrogen atmosphere at a heating rate of 20 °C/min. Freeman–Carroll, Sharp–Wentworth and Phadnis–Deshpande methods were used to calculate the thermal activation energy (Ea the order of reaction (n, entropy change (ΔS, free energy change (ΔF, apparent entropy (S∗ and frequency factor (Z. Phadnis–Deshpande method was used to propose the thermal degradation model for the decomposition pattern of ASF-I terpolymer resin. The order of the decomposition reaction was found to be 0.901. The thermal activation energy determined with the help of these methods was in good agreement with each other. The ASF-I, II and III resins were tested for their inhibitory action against pathogenic bacteria and fungi. The resins show potent inhibitory action against bacteria, such as Escherichia coli, Klebsiella, Staphylococcus aureus and Pseudomonas aeruginosa and fungi viz. Aspergillus flavus, Aspergillus niger, Penicillium sp., Candida albicans, Cryptococcus neoformans and Mucor sp.

  10. The degradation of strong basic anion exchange resins and mixed-bed ion-exchange resins: Effect of degradation products on radionuclide speciation

    International Nuclear Information System (INIS)

    Loon, L.R. van; Hummel, W.

    1999-01-01

    The most important water-soluble products of the radiolytic degradation of anion exchange resins in a cementitious environment are ammonia and methylamines. These ligands do not form complexes with most radionuclides. Exceptions are Ni, Ag, and Pd, which form strong complexes with amines. Other degradation products of anion and mixed-bed ion-exchange resins are of no importance concerning the complexation of trivalent radionuclides. This is shown indirectly by adsorption experiments: The degradation products do not have a significant effect on the adsorption of Eu(III) on calcite. The effect of ammonia and methylamines on the complexation of Ni, Ag, and Pd is investigated by chemical modeling. For Ni and Ag, rather reliable predictions can be made using available thermodynamic data. In the case of Pd, large uncertainties are encountered due to unreliable data and gaps in the set of important species. The system Pd(II)-ammonia-water is explored in detail. Predominant species are inferred by chemical analogy, and their thermodynamic data are estimated. The uncertainty in these estimated and measured but unreliable data is bound by qualitative and quantitative chemical reasoning

  11. Synthesis and thermal degradation studies of melamine formaldehyde resins.

    Science.gov (United States)

    Ullah, Sami; Bustam, M A; Nadeem, M; Naz, M Y; Tan, W L; Shariff, A M

    2014-01-01

    Melamine formaldehyde (MF) resins have been synthesized at different reaction temperature and pH values. Different molar ratios of melamine and formaldehyde were used to synthesize the corresponding resins. The prepared resin samples were characterized by using molecular weight determination viscometry and thermogravimetric analysis (TGA). The maximum percentage of solid content (69.7%) was obtained at pH 8.5 and 75°C temperature. The molecular weight of MF resin was increased with an increase of melamine monomer concentration. The highest residual weight 14.125 wt.% was obtained with sample 10.

  12. Synthesis and Thermal Degradation Studies of Melamine Formaldehyde Resins

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    Sami Ullah

    2014-01-01

    Full Text Available Melamine formaldehyde (MF resins have been synthesized at different reaction temperature and pH values. Different molar ratios of melamine and formaldehyde were used to synthesize the corresponding resins. The prepared resin samples were characterized by using molecular weight determination viscometry and thermogravimetric analysis (TGA. The maximum percentage of solid content (69.7% was obtained at pH 8.5 and 75°C temperature. The molecular weight of MF resin was increased with an increase of melamine monomer concentration. The highest residual weight 14.125 wt.% was obtained with sample 10.

  13. Degradation of resins in EPICOR-II prefilters from Three Mile Island

    International Nuclear Information System (INIS)

    McConnell, J.W. Jr.; Sanders, R.D. Sr.

    1986-01-01

    The Low-Level Waste Data Base Development--EPICOR-II Resin/Liner Investigation Program funded by the U.S. Nuclear Regulatory Commission is investigating the chemical and physical conditions of the synthetic ion exchange resins contained in several EPICOR-II prefilters. Those prefilters were used during cleanup of contaminated water from the Three Mile Island Nuclear Power Station after the March 1979 accident. This paper summarizes results and analyses of the second sampling of resins from prefilters PF-8 and -20. Results are compared with baseline data from tests performed on unirradiated resins supplied by Epicor, Inc. to determine if degradation has occurred due to the high internal radiation dose. Results also are compared with results from tests performed on resins obtained from the first sampling of those two prefilters

  14. Degradation of dental resin composites during intra-oral wear

    NARCIS (Netherlands)

    Yulianto, Heribertus Dedy Kusuma

    2017-01-01

    Dental resin composites have become an integral part of modern dentistry and used worldwide to restore missing tooth structures, to modify tooth color and anatomical contour, and to enhance aesthetics and function. The dentist should be aware that, the aggressive complexity of the oral environment

  15. Interaction between staining and degradation of a composite resin in contact with colored foods

    Directory of Open Access Journals (Sweden)

    Debora Soares-Geraldo

    2011-08-01

    Full Text Available Composite resins might be susceptible to degradation and staining when in contact with some foods and drinks. This study evaluated color alteration and changes in microhardness of a microhybrid composite after immersion in different colored foods and determined whether there was a correlation between these two variables. Eighty composite disks were randomly divided into 8 experimental groups (n = 10: kept dry; deionized water; orange juice; passion fruit juice; grape juice; ketchup; mustard and soy sauce. The disks were individually immersed in their respective test substance at 37 ºC, for a period of 28 days. Superficial analysis of the disk specimens was performed by taking microhardness measurements (Vickers, 50 g load for 45 seconds and color alterations were determined with a spectrophotometer (CINTRA 10- using a CIEL*a*b* system, 400-700 nm wavelength, illuminant d65 and standard observer of 2º at the following times: baseline (before immersion, 1, 7, 14, 21 and 28 days. Results were analyzed by ANOVA and Tukey's test (p < 0.05. Both variables were also submitted to Pearson's correlation test (p < 0.05. The passion fruit group underwent the greatest microhardness change, while the mustard group suffered the greatest color alteration. Significant positive correlation was found between the two variables for the groups deionized water, grape juice, soy sauce and ketchup. Not all color alteration could be associated with surface degradation.

  16. Mechanical fatigue degradation of ceramics versus resin composites for dental restorations.

    Science.gov (United States)

    Belli, Renan; Geinzer, Eva; Muschweck, Anna; Petschelt, Anselm; Lohbauer, Ulrich

    2014-04-01

    For posterior partial restorations an overlap of indication exists where either ceramic or resin-based composite materials can be successfully applied. The aim of this study was to compare the fatigue resistance of modern dental ceramic materials versus dental resin composites in order to address such conflicts. Bar specimens of five ceramic materials and resin composites were produced according to ISO 4049 and stored for 14 days in distilled water at 37°C. The following ceramic materials were selected for testing: a high-strength zirconium dioxide (e.max ZirCAD, Ivoclar), a machinable lithium disilicate (e.max CAD, Ivoclar), a pressable lithium disilicate ceramic (e-max Press, Ivoclar), a fluorapatite-based glass-ceramic (e.max Ceram, Ivoclar), and a machinable color-graded feldspathic porcelain (Trilux Forte, Vita). The composite materials selected were: an indirect machinable composite (Lava Ultimate, 3M ESPE) and four direct composites with varying filler nature (Clearfil Majesty Posterior, Kuraray; GrandioSO, Voco; Tetric EvoCeram, Ivoclar-Vivadent; and CeramX Duo, Dentsply). Fifteen specimens were tested in water for initial strength (σin) in 4-point bending. Using the same test set-up, the residual flexural fatigue strength (σff) was determined using the staircase approach after 10(4) cycles at 0.5 Hz (n=25). Weibull parameters σ0 and m were calculated for the σin specimens, whereas the σff and strength loss in percentage were obtained from the fatigue experiment. The zirconium oxide ceramic showed the highest σin and σff (768 and 440 MPa, respectively). Although both lithium disilicate ceramics were similar in the static test, the pressable version showed a significantly higher fatigue resistance after cyclic loading. Both the fluorapatite-based and the feldspathic porcelain showed equivalent initial and cyclic fatigue properties. From the composites, the highest filled direct material Clearfil Majesty Posterior showed superior fatigue performance

  17. Degradation of resin-dentin bonds of etch-and-rinse adhesive system to primary and permanent teeth

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    Tathiane Larissa Lenzi

    2012-12-01

    Full Text Available The aim of this in vitro study was to compare the degradation of resin-dentin bonds of an etch-and-rinse adhesive system to primary and permanent teeth. Flat superficial coronal dentin surfaces from 5 primary second molars and 5 permanent third molars were etched with phosphoric acid and bonded with an adhesive system (Adper Single Bond 2, 3M ESPE. Blocks of resin composite (Z250, 3M ESPE were built up and the teeth sectioned to produce bonded sticks with a 0.8 mm² cross-sectional area. The sticks of each tooth were randomly divided and assigned to be subjected to microtensile testing immediately (24 h or after aging by water storage (6 months. Data were analyzed by two-way repeated measures ANOVA and Tukey post hoc test (α = 0.05. Failure mode was evaluated using a stereomicroscope (400×. Microtensile values significantly decreased after the 6 months aging, independent of the dentin substrate. In 24 h, the values obtained to primary dentin were lower compared with permanent dentin. This difference was not maintained after aging. Adhesive/mixed failure was predominant in all experimental groups. In conclusion, degradation of resin-dentin bonds of the etch-and-rinse adhesive system occurred after 6 months of water storage; however, the reduction in bond strength values was higher for permanent teeth.

  18. Study of Curing Kinetics and Thermal Degradation of UV Curable Epoxy Acrylate Resin

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    Amrita Sharma

    2008-01-01

    Full Text Available Blends of epoxy acrylate resins (acid values 3, 6.5 & 10 mg KOH/gm Solid with monofunctional monomers (ethoxylated phenol monoacrylate were prepared by physical mixing, having weight ratio 50:50. These blends were cured by using UV radiations in presence of photo initiator (Darocure 1173. The thermal degradation kinetics of these resin blends were studied, using thermo gravimetric analysis in nitrogen atmosphere at a heating rate of 10°C/min. by applying Coats-Red fern equation. According to the analysis, all the coating films degrade in two steps. In the first step of degradation kinetics, R2M follows 1.75 order (n=1.75 and all other coating films follow second order (n=2 kinetics. In second step, R2M & R3M follow half order (n=0.5 kinetics and R1M follow first order (n=1 degradation kinetics. Order of the reaction is obtained on the basis of best fit analysis, and all the parameters were confirmed by regression analysis. From the reaction order, value of activation energy (E and pre exponential factor (Z were calculated by the slop and intercept of the plot between X and Y, respectively.

  19. Determination of degradation conditions of exchange resins containing technetium; Determinacion de condiciones de degradacion de resinas de intercambio conteniendo tecnecio

    Energy Technology Data Exchange (ETDEWEB)

    Rivera S, A.; Monroy G, F.; Quintero P, E., E-mail: aa_1190@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2014-10-15

    The quantification of Tc-99 in spent exchange resins, coming from nuclear power plants, is indispensable to define their administration. The Tc-99 is a pure beta emitter of 210000 years of half-life, volatile and of a high mobility in water and soil. For this reason, the objective of this work is to establish a digestion method of ionic exchange resins containing technetium that retains more than 95% of this radioisotope. Mineralization tests were carried out of a resin Amberlite IRN-150 by means of an oxidation heat, in acid medium, varying the resin mass, the medium volume, the media type, the temperature and the digestion time. The digested samples were analyzed by gas chromatography to estimate the grade of their degradation. The {sup 99m}Tc was used as tracer to determine the technetium percentage recovered after mineralizing the resin. The digestion process depends on the temperature and the resin mass. At higher temperature better mineralization of samples and to greater resin mass to a constant temperature, less degradation of the resin. The spectra beta of the {sup 99m}Tc and {sup 99}Tc are presented. (Author)

  20. The radiolytic and chemical degradation of organic ion exchange resins under alkaline conditions: effect on radionuclide speciation

    International Nuclear Information System (INIS)

    Loon, L. van; Hummel, W.

    1995-10-01

    The formation of water soluble organic ligands by the radiolytic and chemical degradation of several ion exchange resins was investigated under conditions close to those of the near field of a cementitious repository. The most important degradation products were characterised and their role on radionuclide speciation evaluated thoroughly. Irradiation of strong acidic cation exchange resins (Powdex PCH and Lewatite S-100) resulted in the formation of mainly sulphate and dissolved organic carbon. A small part of the carbon (10-20%) could be identified as oxalate. The identity of the remainder is unknown. Complexation studies with Cu 2+ and Ni 2+ showed the presence of two ligands: oxalate and ligand X. Although ligand X could not be identified, it could be characterised by its concentration, a deprotonation constant and a complexation constant for the NiX complex. The influence of oxalate and ligand X on the speciation of radionuclides is examined in detail. For oxalate no significant influence on the speciation of radionuclides is expected. The stronger complexing ligand X may exert some influence depending on its concentration and the values of other parameters. These critical parameters are discussed and limiting values are evaluated. In absence of irradiation, no evidence for the formation of ligands was found. Irradiation of strong basic anion exchange resins (Powdex PAO and Lewatite M-500) resulted in the formation of mainly ammonia, amines and dissolved organic carbon. Up to 50% of the carbon could be identified as methyl-, dimethyl- and trimethylamine. Complexation studies with Eu 3+ showed that the complexing capacity under near field conditions was negligible. The speciation of cations such as Ag, Ni, Cu and Pd can be influenced by the presence of amins. The strongest amine-complexes are formed with Pd and therefore, as an example, the aqueous Pd-ammonia system is examined in great detail. (author) 30 figs., 10 tabs., refs

  1. The radiolytic and chemical degradation of organic ion exchange resins under alkaline conditions: effect on radionuclide speciation

    Energy Technology Data Exchange (ETDEWEB)

    Loon, L. van; Hummel, W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1995-10-01

    The formation of water soluble organic ligands by the radiolytic and chemical degradation of several ion exchange resins was investigated under conditions close to those of the near field of a cementitious repository. The most important degradation products were characterised and their role on radionuclide speciation evaluated thoroughly. Irradiation of strong acidic cation exchange resins (Powdex PCH and Lewatite S-100) resulted in the formation of mainly sulphate and dissolved organic carbon. A small part of the carbon (10-20%) could be identified as oxalate. The identity of the remainder is unknown. Complexation studies with Cu{sup 2+} and Ni{sup 2+} showed the presence of two ligands: oxalate and ligand X. Although ligand X could not be identified, it could be characterised by its concentration, a deprotonation constant and a complexation constant for the NiX complex. The influence of oxalate and ligand X on the speciation of radionuclides is examined in detail. For oxalate no significant influence on the speciation of radionuclides is expected. The stronger complexing ligand X may exert some influence depending on its concentration and the values of other parameters. These critical parameters are discussed and limiting values are evaluated. In absence of irradiation, no evidence for the formation of ligands was found. Irradiation of strong basic anion exchange resins (Powdex PAO and Lewatite M-500) resulted in the formation of mainly ammonia, amines and dissolved organic carbon. Up to 50% of the carbon could be identified as methyl-, dimethyl- and trimethylamine. Complexation studies with Eu{sup 3+} showed that the complexing capacity under near field conditions was negligible. The speciation of cations such as Ag, Ni, Cu and Pd can be influenced by the presence of amins. The strongest amine-complexes are formed with Pd and therefore, as an example, the aqueous Pd-ammonia system is examined in great detail. (author) 30 figs., 10 tabs., refs.

  2. Experimental studies on long-term thermal degradation of enclosed neutron shielding resin

    International Nuclear Information System (INIS)

    Asano, Ryoji; Niomura, Nagao.

    1993-01-01

    The present works are concerned with the thermal degradation or loss of weight of the mixtures contained in vessels. The resins used is an epoxis, 'NS-4-FR' and the fire resisting material mixed is aluminum hydroxide. Firstly, the effect of temperature on degradation was surveyed on the NS-4-FR by continuous heating tests at different temperatures under unenclosed, or open conditions; 125degC, 150degC, 175degC and 200degC. Then, the effect of difference and shape of materials was surveyed at 150degC. Secondly, continuous heating tests were conducted under open and enclosed conditions at 125degC, 150degC and 175degC and the effect of enclosing the mixtures was obtained. Finally, continuous and cyclic heating tests were conducted under enclosed conditions at 125degC, 150degC and 175degC, which was followed by long-term cyclic heating tests at 150degC for more than one year. As the results, following emperical equation was obtained for the thermal degradation at 150degC of the NS-4-FR: W = 0.55 logD - 0.41 where, W: thermal degradation (weight loss), %, D: heating period, day. From this equation, weight loss in 20 years is obtained as less than 2% which is insignificantly small for shielding effect. (J.P.N.)

  3. Resin Systems and Chemistry-Degradation Mechanisms and Durability in Long-Term Durability of Polymeric Matrix Composites. Chapter 1

    Science.gov (United States)

    Hinkley, Jeffrey A.; Connell, John W.

    2012-01-01

    In choosing a polymer-matrix composite material for a particular application, a number of factors need to be weighed. Among these are mechanical requirements, fabrication method (e.g. press-molding, resin infusion, filament winding, tape layup), and use conditions. Primary among the environmental exposures encountered in aerospace structures are moisture and elevated temperatures, but certain applications may require resistance to other fluids and solvents, alkaline agents, thermal cycling, radiation, or rapid, localized heating (for example, lightning strike). In this chapter, the main classes of polymer resin systems found in aerospace composites will be discussed. Within each class, their responses to environmental factors and the associated degradation mechanisms will be reviewed.

  4. Permanganate Degradation of Reillex HPQ Ion Exchange Resin for Use in HB-Line

    International Nuclear Information System (INIS)

    Walker, B.W.

    1999-01-01

    This study evaluated the use of Reillex TM HPQ resin as a replacement for the Ionac A-641 resin currently authorized for use in H B-Line. The study concentrated on the ability of the existing alkaline permanganate digestion process to convert spent resin for disposal

  5. Long-term degradation of resin-based cements in substances present in the oral environment: influence of activation mode

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    Eduardo Moreira da SILVA

    2013-06-01

    Full Text Available Indirect restorations in contact with free gingival margins or principally within the gingival sulcus, where the presence of organic acids produced by oral biofilm is higher, may present faster degradation of the resin-based cement pellicle. Objectives To investigate the degradation of four resin-based cements: Rely X ARC (R, Variolink II (V, Enforce (E and All Cem (A, after immersion in distilled water (DW, lactic acid (LA and artificial saliva (AS and to analyze the influence of the activation mode on this response. Material and Methods Two activation modes were evaluated: chemical (Ch and dual (D. In the dual activation, a two-millimeter thick ceramic disk (IPS Empress System was interposed between the specimen and light-curing unit tip. Specimens were desiccated, immersed in distilled water, artificial saliva and lactic acid 0.1 M at 37°C for 180 days, weighed daily for the first 7 days, and after 14, 21, 28, 90 and 180 days and were desiccated again. Sorption and solubility (µg/mm 3 were calculated based on ISO 4049. The data were submitted to multifactor analysis of variance (MANOVA and Tukey's HSD test for media comparisons (α=0.05. Results Sorption was higher after immersion in LA (pD (p<0.05. The lowest solubility was presented by R (p<0.05. Conclusions Lactic acid increased the degradation of resin-based cements. Moreover, the physical component of activation, i.e., light-activation, contributed to a low degradation of resin-based cements.

  6. Sequential Isolation of Saturated, Aromatic, Resinic and Asphaltic Fractions Degrading Bacteria from Oil Contaminated Soil in South Sumatera

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    Pingkan Aditiawati

    2012-04-01

    Full Text Available Sequential isolation has been conducted to obtain isolates of saturated, aromatic, resin, and asphaltene fractions degrading bacteria from oil contaminated sites. Five soil samples were collected from South Sumatera. These were analyzed using soil extract medium enriched with oil recovery or Remaining-Oil recovery Degradated (ROD as sole carbon and energy sources according to the isolation stage. ROD at the end of every isolation stage analyzed oil fractions by use of the SARA analysis method. Six isolates of bacteria have been selected, one isolate was fraction saturates degrading bacteria that are Mycobacterium sp. T1H2D4-7 at degradation rate 0.0199 mgs/h with density 8.4x106 cfu/g from stage I. The isolate T2H1D2-4, identified as Pseudomonas sp. was fraction aromatics degrading bacteria at accelerate 0.0141 mgs/h with density 5.1x106 cfu/g are obtained at stage II. Two isolates namely Micrococcus sp. T3H2D4-2 and Pseudomonas sp. T1H1D5-5 were fraction resins degrading bacteria by accelerate 0.0088 mgs/h at density 5.6x106 cfu/g and 0.0089 mgs/h at density 5.7x106 cfu/g are obtained at stage III. Isolation of stage IV has been obtained two isolates Pseudomonas sp. T4H1D3-1and Pseudomonas sp. T4H3D5-4 were fraction asphaltenes degrading bacteria by accelerate 0.0057 mgs/h at density 5.6x106 cfu/g and accelerate 0.0058 mgs/h at density 5.7x106 cfu/g.

  7. New Carbon Source From Microbial Degradation of Pre-Production Resin Pellets from the North Pacific Gyre

    Science.gov (United States)

    Neal, A.; Mielke, R.; Stam, C. N.; Gonsior, M.; Tsapin, A. I.; Lee, G.; Leftwich, B.; Narayan, R.; Coleman, H.; Argyropoulos, N.; Sheavly, S. B.; Gorby, Y. A.

    2011-12-01

    Numerous pollutants are transported through the world's oceans that impact oceanic health. Diffuse sources include land-based runoff, atmospheric depositions, shipping industry wastes, and others. Synthetic polymer marine debris is a multi-faceted problem that includes interactions with environmental toxins, carbon cycling systems, ocean surface chemistry, fine minerals deposition, and nano-particles. The impact that synthetic polymer-microbe interactions have on carbon input into the open ocean is poorly understood. Here we demonstrate that both biotic and abiotic processes contribute to degradation of pre-production resin pellets (PRPs), in open ocean environments and new methodologies to determine carbon loss from this synthetic polymer debris. Our data shows that material degradation of environmental polyethylene PRPs can potentially deposit 13 mg/g to 65 mg/g of carbon per PRP into our marine environments. Environmental pre-production resin pellets were collected on the S/V Kaisei cruise in 2009 which covered over 3,000 nautical miles and sampled over 102,000 m3 of the first 15cm of the water column in the Subtropical Convergence Zone of the North Pacific Gyre. Environmental PRP degradation and the role microbial communities play in this was evaluated using a combination of Fourier transform infrared spectroscopy, environmental scanning electron microscopy, scanning transmission electron microscopy, X-ray microtomography, and ArcGIS mapping. More research is needed to understand the environmental impact of this new carbon source arising from synthetic polymers as they degrade in oceanic environments.

  8. Resistance to bond degradation between dual-cure resin cements and pre-treated sintered CAD-CAM dental ceramics.

    Science.gov (United States)

    Osorio, Raquel; Castillo-de Oyagüe, Raquel; Monticelli, Francesca; Osorio, Estrella; Toledano, Manuel

    2012-07-01

    To evaluate the bond stability of resin cements when luted to glass-reinforced alumina and zirconia CAD/CAM dental ceramics. Eighteen glass-infiltrated alumina and eighteen densely sintered zirconia blocks were randomly conditioned as follows: Group 1: No treatment; Group 2: Sandblasting (125 µm Al₂O₃-particles); and Group 3: Silica-coating (50 µm silica-modified Al₂O₃-particles). Composite samples were randomly bonded to the pretreated ceramic surfaces using different resin cements: Subgroup 1: Clearfil Esthetic Cement (CEC); Subgroup 2: RelyX Unicem (RXU); and Subgroup 3: Calibra (CAL). After 24 h, bonded specimens were cut into 1 ± 0.1 mm² sticks. One-half of the beams were tested for microtensile bond strength (MTBS). The remaining one-half was immersed in 10 % NaOCl aqueous solution (NaOClaq) for 5 h before testing. The fracture pattern and morphology of the debonded surfaces were assessed with a field emission gun scanning electron microscope (FEG-SEM). A multiple ANOVA was conducted to analyze the contributions of ceramic composition, surface treatment, resin cement type, and chemical challenging to MTBS. The Tukey test was run for multiple comparisons (p Resin-ceramic interfacial longevity depended on cement selection rather than on surface pre-treatments. The MDP-containing and the self-adhesive resin cements were both suitable for luting CAD/CAM ceramics. Despite both cements being prone to degradation, RXU luted to zirconia or untreated or sandblasted alumina showed the most stable interfaces. CAL experimented spontaneous debonding in all tested groups.

  9. Thermal degradation and evolved gas analysis: A polymeric blend of urea formaldehyde (UF and epoxy (DGEBA resin

    Directory of Open Access Journals (Sweden)

    Tansir Ahamad

    2014-12-01

    Full Text Available A polymeric blend has been prepared using urea formaldehyde (UF and epoxy (DGEBA resin in 1:1 mass ratio. The thermal degradation of UF/epoxy resin blend (UFE was investigated by using thermogravimetric analyses (TGA, coupled with FTIR and MS. The results of TGA revealed that the pyrolysis process can be divided into three stages: drying process, fast thermal decomposition and cracking of the sample. There were no solid products except ash content for UFE during combustion at high temperature. The total mass loss during pyrolysis at 775 °C is found to be 97.32%, while 54.14% of the original mass was lost in the second stage between 225 °C and 400 °C. It is observed that the activation energy of the second stage degradation during combustion (6.23 × 10−4 J mol−1 is more than that of pyrolysis (5.89 × 10−4 J mol−1. The emissions of CO2, CO, H2O, HCN, HNCO, and NH3 are identified during thermal degradation of UFE.

  10. Contribution To Degradation Study, Behavior Of Unsaturated Polyester Resin Under Neutron Irradiation

    Science.gov (United States)

    Abellache, D.; Lounis, A.; Taïbi, K.

    2010-01-01

    Applications of unsaturated polyester thermosetting resins are numerous in construction sector, in transport, electric spare parts manufactures, consumer goods, and anticorrosive materials. This survey reports the effect of thermosetting polymer degradation (unsaturated polyester): degradation by neutrons irradiation. In order to evaluate the deterioration of our material, some comparative characterizations have been done between standard samples and damaged ones. Scanning electron microscopy (SEM), ultrasonic scanning, hardness test (Shore D) are the techniques which have been used. The exposure to a neutrons flux is carried out in the column of the nuclear research reactor of Draria (Algiers-Algeria). The energetic profile of the incidental fluxes is constituted of fast neutrons (ΦR = 3.1012n.cm-2.s-1, E = 2 Mev) of thermal neutrons (ΦTH = 1013n.cm-2.s-1; E = 0.025 ev) and epithermal neutrons (Φepi = 7.1011 n.cm-2.s-1; E>4,9 ev). The received dose flow is 0,4 Kgy. We notice only a few scientific investigations can be found in this field. In comparison with the standard sample (no exposed) it is shown that the damage degree is an increasing process with the exposure. Concerning the description of irradiation effects on polymers, we can advance that several reactions are in competition : reticulation, chain break, and oxidation by radical mechanism. In our case the incidental particle of high energy fast neutrons whose energy is greater or equal to 2 Mev, is braked by the target with a nuclear shock during which the incidental particle transmits a part of its energy to an atom. If the energy transfer is sufficient, the nuclear shock permits to drive out an atom of its site the latter will return positioning interstitially, the energy that we used oversteps probably the energy threshold (displacement energy). This fast neutrons collision with target cores proceeds to an indirect ionization by the preliminary creation of excited secondary species that will

  11. MICROWAVE INDUCED DEGRADATION OF GLASS FIBER REINFORCED POLYESTER FOR FIBER AND RESIN RECOVERY

    DEFF Research Database (Denmark)

    Ucar, Hülya; Nielsen, Rudi Pankratz; Søgaard, Erik Gydesen

    A solvolysis process to depolymerize the resin in glass fiber reinforced composites and recover the glass fibers has been investigated using microwave induced irradiation. The depolymerization was carried out in HNO3 with concentrations in the range of 1M-7M and in KOH with concentrations ranging...... of depolymerization was achieved using KOH at concentrations ranging from 1-3.5M. Maximum 63 % resin removal was achieved using 1 M KOH and the resin removal efficiency decreased at higher KOH concentrations (3.5M). The glass fiber surfaces were damaged at both concentrations with more pronounced damages using 3.5M...... KOH. It was not possible to recover monomers using KOH....

  12. Color degradation of acrylic resin denture teeth as a function of liquid diet: ultraviolet-visible reflection analysis.

    Science.gov (United States)

    Hipólito, Ana Carolina; Barão, Valentim A; Faverani, Leonardo P; Ferreira, Mayara B; Assunção, Wirley G

    2013-10-01

    The effect of different beverages on acrylic resin denture teeth color degradation is evaluated. Ten acrylic resin denture teeth brands were evaluated: Art Plus (AP), Biolux (BX), Biotone IPN (BI), Magister (MG), Mondial 6 (MD), Premium 6 (PR), SR Vivodent PE (SR), Trilux (TR), Trubyte Biotone (TB), and Vipi Dent Plus (VP). Teeth were immersed in staining solutions (coffee, cola, and orange juice) or artificial saliva (control) (n=6) for 1, 7, 15, or 30 days. Specimen colors were evaluated spectrophotometrically based on the Commission Internationale d'Eclairage L*a*b* system. Color differences (ΔE) were calculated between the baseline and post-staining results. Data were evaluated by analysis of variance and Tukey test (α = 0.05). BI (1.82 ± 0.95) and TR (1.78 ± 0.72) teeth exhibited the greatest ΔE values, while BX (0.88 ± 0.43) and MD (1.09 ± 0.44) teeth were the lowest, regardless of solution and measurement period, and were different from BI and TR teeth (P denture teeth color alterations than orange juice and saliva (P denture teeth color alterations. Greater immersion times caused higher denture teeth color changes. The lifespan of removable dentures and the aesthetic satisfaction of several edentulous patients may be increased with the use of stain-resistant artificial denture teeth.

  13. Does liver-intestine significantly degrade circulating endogenous substance P in man?

    DEFF Research Database (Denmark)

    Henriksen, Jens Henrik Sahl; Schaffalitzky de Muckadell, O B; Bülow, J B

    1986-01-01

    Elevated concentrations of circulating substance P in patients with liver insufficiency have been ascribed to decreased hepatic degradation. To establish a possible biodegradation of the peptide in liver-intestine and kidneys, the concentration of endogenous immunoreactive substance P...... was determined in various vascular beds during a right-sided catheterization in 13 subjects without liver insufficiency. All subjects had normal values of circulating substance P, and no significant difference was found between systemic plasma and hepatic venous or renal venous concentrations of substance P....... The results indicate that degradation of circulating endogenous substance P in man is not confined to liver-intestine or kidney but may take place in many tissues....

  14. Degradation of ion spent resin using the Fenton's reagent; Degradacao da resina de troca ionica utilizando o reagente de Fenton

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Leandro Goulart de

    2013-07-01

    The most common method for spent radioactive ion exchange resin treatment is its immobilization in cement, which reduces the radionuclides release into the environment. Although this method is efficient, it increases considerably the final volume of the waste due to the low incorporation capacity. The objective of this work was to develop a degradation method of spent resins arising from the nuclear research reactor located at the Nuclear and Energy Research Institute (IPEN-CNEN/SP), using an Advanced Oxidation Process (AOP) with Fenton's reagents. This method would allow a higher incorporation in cement. Three different resins were evaluated: cationic, anionic and a mixture of both resins. The reactions were conducted varying the catalyst concentration (25, 50, 100 and 150 mM), the volume of hydrogen peroxide (320 to 460 mL), and three different temperatures, 50, 60 and 70 deg C. Degradation of about 98% was achieved using a 50 mM catalyst solution and 330 mL of hydrogen peroxide solution. The most efficient temperature was 60 deg C. (author)

  15. IMPACTS OF WETLAND DEGRADATION IN NIGER DELTA NIGERIA AND ITS SIGNIFICANCE IN FLOOD CONTROL

    Directory of Open Access Journals (Sweden)

    Enwere Chidimma Loveline

    2015-08-01

    Full Text Available  Wetlands perform a wide variety of functions that include flood control, ground water recharge, shore line stabilization, storm protection and climate moderation. However, despite these huge wetland functions, it has witnessed poor appreciation and dreadful conditions. Niger Delta has witnessed constant coastal erosion and rising sea level, this has led to large portions of the landmass being eroded. This paper aims to review some environmental effects of flooding in the Niger Delta region of Nigeria to provide the desired knowledge of role that wetlands play in reducing flood impacts. However, having witnessed the flood, the experience opened my eyes to the environmental challenges facing Niger Delta with respect to Wetlands degradation, poor perception of wetland values and functions, poor environmental practices and non-implementation of environmental regulations. This memorable experience rekindled the desire and motivation to seek a solution to wetland degradation with the aim of recognizing significance of wetlands at the centre of achieving both livelihood and biodiversity improvements to address coastal flooding problem.The study therefore concludes that wetlands are very significant in flood control and thus the conservation and restoration of wetlands, should put in place measures to reduce wetland destruction.International Journal of EnvironmentVolume-4, Issue-3, June-August 2015Page: 177-184

  16. Oxidative degradation of low and intermediate level Radioactive organic wastes 2. Acid decomposition on spent Ion-Exchange resins

    International Nuclear Information System (INIS)

    Ghattas, N.K.; Eskander, S.B.

    1995-01-01

    The present work provides a simplified, effective and economic method for the chemical decomposition of radioactively contaminated solid organic waste, especially spent ion - exchange resins. The goal is to achieve volume reduction and to avoid technical problems encountered in processes used for similar purposes (incineration, pyrolysis). Factors efficiency and kinetics of the oxidation of the ion exchange resins in acid medium using hydrogen peroxide as oxidant, namely, duration of treatment and the acid to resin ratio were studied systematically on a laboratory scale. Moreover the percent composition of the off-gas evolved during the decomposition process was analysed. 3 figs., 5 tabs

  17. Does liver-intestine significantly degrade circulating endogenous substance P in man?

    DEFF Research Database (Denmark)

    Henriksen, Jens Henrik Sahl; Schaffalitzky de Muckadell, O B; Bülow, J B

    1986-01-01

    Elevated concentrations of circulating substance P in patients with liver insufficiency have been ascribed to decreased hepatic degradation. To establish a possible biodegradation of the peptide in liver-intestine and kidneys, the concentration of endogenous immunoreactive substance P was determi......Elevated concentrations of circulating substance P in patients with liver insufficiency have been ascribed to decreased hepatic degradation. To establish a possible biodegradation of the peptide in liver-intestine and kidneys, the concentration of endogenous immunoreactive substance P....... The results indicate that degradation of circulating endogenous substance P in man is not confined to liver-intestine or kidney but may take place in many tissues....

  18. The quantitative significance of Syntrophaceae and syntrophic partnerships in methanogenic degradation of crude oil alkanes.

    Science.gov (United States)

    Gray, N D; Sherry, A; Grant, R J; Rowan, A K; Hubert, C R J; Callbeck, C M; Aitken, C M; Jones, D M; Adams, J J; Larter, S R; Head, I M

    2011-11-01

    Libraries of 16S rRNA genes cloned from methanogenic oil degrading microcosms amended with North Sea crude oil and inoculated with estuarine sediment indicated that bacteria from the genera Smithella (Deltaproteobacteria, Syntrophaceace) and Marinobacter sp. (Gammaproteobacteria) were enriched during degradation. Growth yields and doubling times (36 days for both Smithella and Marinobacter) were determined using qPCR and quantitative data on alkanes, which were the predominant hydrocarbons degraded. The growth yield of the Smithella sp. [0.020 g(cell-C)/g(alkane-C)], assuming it utilized all alkanes removed was consistent with yields of bacteria that degrade hydrocarbons and other organic compounds in methanogenic consortia. Over 450 days of incubation predominance and exponential growth of Smithella was coincident with alkane removal and exponential accumulation of methane. This growth is consistent with Smithella's occurrence in near surface anoxic hydrocarbon degrading systems and their complete oxidation of crude oil alkanes to acetate and/or hydrogen in syntrophic partnership with methanogens in such systems. The calculated growth yield of the Marinobacter sp., assuming it grew on alkanes, was [0.0005 g(cell-C)/g(alkane-C)] suggesting that it played a minor role in alkane degradation. The dominant methanogens were hydrogenotrophs (Methanocalculus spp. from the Methanomicrobiales). Enrichment of hydrogen-oxidizing methanogens relative to acetoclastic methanogens was consistent with syntrophic acetate oxidation measured in methanogenic crude oil degrading enrichment cultures. qPCR of the Methanomicrobiales indicated growth characteristics consistent with measured rates of methane production and growth in partnership with Smithella. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  19. Resin composites

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Peutzfeldt, Anne; Lussi, Adrian

    2014-01-01

    OBJECTIVE: To investigate how the modulus of elasticity of resin composites influences marginal quality in restorations submitted to thermocyclic and mechanical loading. METHODS: Charisma, Filtek Supreme XTE and Grandio were selected as they were found to possess different moduli of elasticity...... of resin composite (p=0.81) on the quality of dentine margins was observed, before or after loading. Deterioration of all margins was evident after loading (p....008). CONCLUSIONS: The resin composite with the highest modulus of elasticity resulted in the highest number of gap-free enamel margins but with an increased incidence of paramarginal enamel fractures. CLINICAL SIGNIFICANCE: The results from this study suggest that the marginal quality of restorations can...

  20. Advanced degradation of brominated epoxy resin and simultaneous transformation of glass fiber from waste printed circuit boards by improved supercritical water oxidation processes.

    Science.gov (United States)

    Liu, Kang; Zhang, Zhiyuan; Zhang, Fu-Shen

    2016-10-01

    This work investigated various supercritical water oxidation (SCWO) systems, i.e. SCWO1 (only water), SCWO2 (water+H2O2) and SCWO3 (water+H2O2/NaOH), for waste printed circuit boards (PCBs) detoxification and recycling. Response surface methodology (RSM) was applied to optimize the operating conditions of the optimal SCWO3 systems. The optimal reaction conditions for debromination were found to be the NaOH of 0.21g, the H2O2 volume of 9.04mL, the time of 39.7min, maximum debromination efficiency of 95.14%. Variance analysis indicated that the factors influencing debromination efficiency was in the sequence of NaOH>H2O2>time. Mechanism studies indicated that the dissociated ions from NaOH in supercritical water promoted the debromination of brominated epoxy resins (BERs) through an elimination reaction and nucleophilic substitution. HO2, produced by H2O2 could induce the oxidation of phenol ring to open (intermediates of BERs), which were thoroughly degraded to form hydrocarbons, CO2, H2O and NaBr. In addition, the alkali-silica reaction between OH(-) and SiO2 induced the phase transformation of glass fibers, which were simultaneously converted into anorthite and albite. Waste PCBs in H2O2/NaOH improved SCWO system were fully degraded into useful products and simultaneously transformed into functional materials. These findings are helpful for efficient recycling of waste PCBs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Physico-chemical study of the thermal degradation of ions exchange resins of nuclear origin: research of conditions to limit the pollution transfer, application to electric cables

    International Nuclear Information System (INIS)

    Antonetti, P.

    1999-01-01

    The ions exchange resins are one solid form of radioactive wastes. They are found mainly during the demineralization operations of the water from reactors cooling systems. This study aims to determine the conditions of a thermal processing leading to the production of a smaller residue, containing the whole activity. A protocol is proposed and validated on resins allowing a decrease of the volume of 63% for 99,93% of the activity. (A.L.B.)

  2. Significance of urinary fibrin/fibrinogen degradation products in renal diseases measured by a highly sensitive ELISA.

    Science.gov (United States)

    Shibata, T; Magari, Y; Perparim, K; Sumie, A; Ishii, T; Tomo, T; Sato, J; Yasumori, R; Nasu, M

    1995-01-01

    The urinary fibrin/fibrinogen degradation products (FDP), as sensitive indicators of various renal disorders, have been measured by several methods. For their determination, a new and highly sensitive enzyme-linked immunosorbent assay not requiring the urine concentration has been developed. The study comprised 42 patients with nonnephrotic chronic glomerulonephritis (CGN), 23 patients with primary nephrotic syndrome (NS), and 29 healthy adults. The results were as follows: (1) the content of urinary FDP in normal subjects was 10.30 +/- 9.08 ng/ml; (2) the mean level of urinary FDP in both CGN and NS groups was significantly higher than in normal subjects; (3) in the CGN group itself there was a tendency for an increase of urinary FDP during more active forms of the disease, and (4) there was a significant correlation between urinary FDP and urinary protein in the CGN group, whereas no correlation was observed in the NS group. These results suggest that the major part of urinary FDP in the CGN group derives from the increased filtration, while its origin in the NS group is not related to increased filtration only, but may also have involved intraglomerular coagulation abnormalities. The newly developed enzyme-linked immunosorbent assay can detect urinary FDP levels lower than 3.9 ng/ml. Therefore, this method can be of great value in determining the degree of abnormalities of intraglomerular coagulation and fibrinolysis in renal diseases.

  3. Synthesis, structural characterization, and performance evaluation of resorcinol-formaldehyde (R-F) ion-exchange resin

    International Nuclear Information System (INIS)

    Hubler, T.L.; Franz, J.A.; Shaw, W.J.; Bryan, S.A.; Hallen, R.T.; Brown, G.N.; Bray, L.A.; Linehan, J.C.

    1995-08-01

    The 177 underground storage tanks at the DOE's Hanford Site contain an estimated 180 million tons of high-level radioactive wastes. It is desirable to remove and concentrate the highly radioactive fraction of the tank wastes for vitrification. Resorcinol-formaldehyde (R-F) resin, an organic ion-exchange resin with high selectivity and capacity for the cesium ion, which is a candidate ion-exchange material for use in remediation of tank wastes. The report includes information on the structure/function analysis of R-F resin and the synthetic factors that affect performance of the resin. CS-100, a commercially available phenol-formaldehyde (P-F) resin, and currently the baseline ion-exchanger for removal of cesium ion at Hanford, is compared with the R-F resin. The primary structural unit of the R-F resin was determined to consist of a 1,2,3,4-tetrasubstituted resorcinol ring unit while CS-100, was composed mainly of a 1,2,4-trisubstituted ring. CS-100 shows the presence of phenoxy-ether groups, and this may account for the much lower decontamination factor of CS-100 for cesium ion. Curing temperatures for the R-F resin were found to be optimal at 105--130C. At lower temperatures, insufficient curing, hence crosslinking, of the polymer resin occurs and selectivity for cesium drops. Curing at elevated temperatures leads to chemical degradation. Optimal particle size for R-F resin is in the range of 20--50 mesh-sized particles. R-F resin undergoes chemical degradation or oxidation which destroys ion-exchange sites. The ion-exchange sites (hydroxyl groups) are converted to quinones and ketones. CS-100, though it has much lower performance for cesium ion-exchange, is significantly more chemically stable than R-F resin. To gamma radiation, CS-100 is more radiolytically stable than R-F resin

  4. Synthesis, structural characterization, and performance evaluation of resorcinol-formaldehyde (R-F) ion-exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    Hubler, T.L.; Franz, J.A.; Shaw, W.J.; Bryan, S.A.; Hallen, R.T.; Brown, G.N.; Bray, L.A.; Linehan, J.C.

    1995-08-01

    The 177 underground storage tanks at the DOE`s Hanford Site contain an estimated 180 million tons of high-level radioactive wastes. It is desirable to remove and concentrate the highly radioactive fraction of the tank wastes for vitrification. Resorcinol-formaldehyde (R-F) resin, an organic ion-exchange resin with high selectivity and capacity for the cesium ion, which is a candidate ion-exchange material for use in remediation of tank wastes. The report includes information on the structure/function analysis of R-F resin and the synthetic factors that affect performance of the resin. CS-100, a commercially available phenol-formaldehyde (P-F) resin, and currently the baseline ion-exchanger for removal of cesium ion at Hanford, is compared with the R-F resin. The primary structural unit of the R-F resin was determined to consist of a 1,2,3,4-tetrasubstituted resorcinol ring unit while CS-100, was composed mainly of a 1,2,4-trisubstituted ring. CS-100 shows the presence of phenoxy-ether groups, and this may account for the much lower decontamination factor of CS-100 for cesium ion. Curing temperatures for the R-F resin were found to be optimal at 105--130C. At lower temperatures, insufficient curing, hence crosslinking, of the polymer resin occurs and selectivity for cesium drops. Curing at elevated temperatures leads to chemical degradation. Optimal particle size for R-F resin is in the range of 20--50 mesh-sized particles. R-F resin undergoes chemical degradation or oxidation which destroys ion-exchange sites. The ion-exchange sites (hydroxyl groups) are converted to quinones and ketones. CS-100, though it has much lower performance for cesium ion-exchange, is significantly more chemically stable than R-F resin. To gamma radiation, CS-100 is more radiolytically stable than R-F resin.

  5. Action of ionizing radiation on epoxy resins

    Energy Technology Data Exchange (ETDEWEB)

    Van de Voorde, M. E.

    1970-12-01

    The resistance of classical and experimental epoxy resins to irradiation was studied. The resistance to irradiation of epoxy resins of diverse compositions as well as the development of resins having a radioresistance that approaches that of certain ceramics are discussed. Sources of irradiation and the techniques of dosimetry used are described. The structures of certain epoxy resins and of hardeners are given. The preparation of these resins and their physical properties is described. The effects of radiation on epoxy resins, as well as conditions of irradiation, and suggested mechanisms for degradation of the irradiated resins are discussed. The relationship between chemical structure of the resins and their physical properties is evaluated. (115 references) (JCB)

  6. Long term stability of cannabis resin and cannabis extracts

    DEFF Research Database (Denmark)

    Lindholst, Christian

    2010-01-01

    at room temperature, 4 °C and - 20 °C for up to 4 years. Acidic THC degrades exponentially via decarboxylation with concentration halve-lives of approximately 330 and 462 days in daylight and darkness, respectively. The degradation of neutral THC seems to occur somewhat slower. When cannabinoids were...... stored in extracted form at room temperature the degradation rate of acidic THC increased significantly relative to resin material with concentration halve-lives of 35 and 91 days in daylight and darkness, respectively. Once cannabis material is extracted into organic solvents, care should be taken...

  7. Development of heat-resistant neutron shielding resin for high payload metal cask

    International Nuclear Information System (INIS)

    Kamoshida, Mamoru; Hiranuma, Takeshi; Shimizu, Masashi

    2007-01-01

    A new neutron shielding resin has been developed for a dual-purpose metal cask. The resin is composed of a cycloaliphatic epoxy, anhydrous acid, catalyst, aluminum hydroxide and boron tetracarbide. Its long-term stability was verified by thermal degradation tests. Estimated weight loss of the resin during storage was about 1-2%. Because the curing reaction of epoxy and curing reagents was moderate at room temperature, a large amount of resin could be treated at one time which would lower fabrication cost. The fabrication process was verified by a full-scale mock-up test. No significant voids or cracks were found in the resin and uniform elemental composition was confirmed. (author)

  8. Systems biology defines the biological significance of redox-active proteins during cellulose degradation in an aerobic bacterium.

    Science.gov (United States)

    Gardner, Jeffrey G; Crouch, Lucy; Labourel, Aurore; Forsberg, Zarah; Bukhman, Yury V; Vaaje-Kolstad, Gustav; Gilbert, Harry J; Keating, David H

    2014-10-08

    Microbial depolymerization of plant cell walls contributes to global carbon balance and is a critical component of renewable energy. The genomes of lignocellulose degrading microorganisms encode diverse classes of carbohydrate modifying enzymes, although currently there is a paucity of knowledge on the role of these proteins in vivo. We report the comprehensive analysis of the cellulose degradation system in the saprophytic bacterium Cellvibrio japonicus. Gene expression profiling of C. japonicus demonstrated that three of the 12 predicted β-1,4 endoglucanases (cel5A, cel5B, and cel45A) and the sole predicted cellobiohydrolase (cel6A) showed elevated expression during growth on cellulose. Targeted gene disruptions of all 13 predicted cellulase genes showed that only cel5B and cel6A were required for optimal growth on cellulose. Our analysis also identified three additional genes required for cellulose degradation: lpmo10B encodes a lytic polysaccharide monooxygenase (LPMO), while cbp2D and cbp2E encode proteins containing carbohydrate binding modules and predicted cytochrome domains for electron transfer. CjLPMO10B oxidized cellulose and Cbp2D demonstrated spectral properties consistent with redox function. Collectively, this report provides insight into the biological role of LPMOs and redox proteins in cellulose utilization and suggests that C. japonicus utilizes a combination of hydrolytic and oxidative cleavage mechanisms to degrade cellulose. © 2014 John Wiley & Sons Ltd.

  9. EDF specifications on nuclear grade resins

    International Nuclear Information System (INIS)

    Mascarenhas, Darren; Gressier, Frederic; Taunier, Stephane; Le-Calvar, Marc; Ranchoux, Gilles; Marteau, Herve; Labed, Veronique

    2012-09-01

    Ion exchange resins are widely used across EDF, especially within the nuclear division for the purification of water. Important applications include primary circuit, secondary circuit and effluent treatment, which require high quality nuclear grade resins to retain the dissolved species, some of which may be radioactive. There is a need for more and more efficient purification in order to decrease worker dose during maintenance but also to decrease volumes of radioactive resin waste. Resin performance is subject to several forms of degradation, including physical, chemical, thermal and radioactive, therefore appropriate resin properties have to be selected to reduce such effects. Work has been done with research institutes, manufacturers and on EDF sites to select these properties, create specifications and to continuously improve on these specifications. An interesting example of research regarding resin performance is the resin degradation under irradiation. Resins used in the CVCS circuit of EDF nuclear power plants are subject to irradiation over their lifetime. A study was carried out on the effects of total integrated doses of 0.1, 1 and 10 MGy on typically used EDF mixed bed resins in a 'mini-CVCS' apparatus to simultaneously test actual primary circuit fluid. The tests confirmed that the resins still perform efficiently after a typical CVCS radiation dose. Certain resins also need additional specifications in order to maintain the integrity of the particular circuits they are used in. Recently, EDF has updated its requirements on these high purity nuclear grade resins, produced generic doctrines for all products and materials used on site which include resins of all grades, and as a result have also updated a guide on recommended resin usage for the French fleet of reactors. An overview of the evolutions will be presented. (authors)

  10. Protein a resin lifetime study: Evaluation of protein a resin performance with a model-based approach in continuous capture.

    Science.gov (United States)

    Behere, Ketki; Cha, Bumjoon; Yoon, Seongkyu

    2018-01-22

    A modified shrinking core model (MSCM) has been used to describe the mechanism for the degradation of Protein A resin particles taking place under continuous chromatographic operation. The model is based on the hypothetical shrinkage of the boundary layer of the resin particles, which house the active Protein A ligands within their pores. The caustic during the sanitization phase of chromatography has been determined to cause the Protein A ligand degradation. Protein A resins provided by manufacturers possess unique caustic stability, which has been used in MSCM to appraise the ligand degradation. The kinetic model utilized semiempirical parameters including diffusion constant, rate constant, stoichiometric factor, and reaction order. The parameters were estimated from column breakthrough experiments to simulate continuous Protein A chromatography for three distinct resins. The reaction order has been identified as the key parameter for predicting the degradation kinetics. The recorded reaction orders vary for three different resins with the resin B showing the highest reaction order of 4 and lowest being 1.65 for the resin C. The model can predict the effects of caustic on resin performance and displayed that minimal degradation of the resins A and B occurred, when exposed to 0.1 N and 0.2N NaOH, retaining up to 96% binding capacity after 240 cycles. The adsorption study conducted for the resin B demonstrated the dynamic physical and chemical changes transpiring through the life cycle of the resin, further supported the degradation model. The performance data demonstrate that the resin B exhibits the desirable performance, with higher reaction order indicating slower resin degradation, higher binding capacities, and increased sustenance of this binding capacity for extended duration. The degradation model can be extended to build effective cleaning strategies for continuous downstream processing.

  11. Stability of IRA-45 solid amine resin as a function of carbon dioxide absorption and steam desorption cycling

    Science.gov (United States)

    Wood, Peter C.; Wydeven, Theodore

    1987-01-01

    The removal of CO2 from the NASA Space Station's cabin atmosphere, which may be undertaken by a solid-amine water (steam)-desorbed system, is presently evaluated with a view to long-term amine resin stability and adsorption/desorption cycling by means of an automated laboratory flow-testing facility. While the CO2-adsorption capacity of the IRA-45 amine resin used gradually decreased over time, the rate of degradation significantly decreased after the first 10 cycles. Attention is given to the presence (and possible need for removal) of trimethylamine in the process air downstream of the resin bed.

  12. Thermal rearrangement of novolak resins used in microlithography

    Science.gov (United States)

    Hardy, Ricky; Zampini, Anthony; Monaghan, Michael J.; O'Leary, Michael J.; Cardin, William J.; Eugster, Timothy J.

    1995-06-01

    Changes in phenolic-formaldehyde resin properties are described in terms of thermal exposure. At high temperature, resin molecular weight, dissolution properties and chemical composition change depending on the presence or absence of monomers. Without monomer in the resin melt at 220 degree(s)C, resin molecular weight increases with a corresponding decrease in dissolution rate. In the presence of monomer, molecular weight generally decreases. Dissolution rate may fluctuate depending on the monomer mixture. Three,five- Xylenol and 2,3,5-trimethylphenol co-monomers induced the most extreme changes in resin properties with thermal treatment. Resin degradation-recombination processes suggest a classical Friedel-Craft rearrangement mechanism.

  13. Plastic casting resin poisoning

    Science.gov (United States)

    Epoxy poisoning; Resin poisoning ... Epoxy and resin can be poisonous if they are swallowed or their fumes are breathed in. ... Plastic casting resins are found in various plastic casting resin products.

  14. Neuraminidase-1 contributes significantly to the degradation of neuronal B-series gangliosides but not to the bypass of the catabolic block in Tay–Sachs mouse models

    Directory of Open Access Journals (Sweden)

    Z.K. Timur

    2015-09-01

    Full Text Available Tay–Sachs disease is a severe lysosomal storage disorder caused by mutations in the HEXA gene coding for α subunit of lysosomal β-Hexosaminidase A enzyme, which converts GM2 to GM3 ganglioside. HexA−/− mice, depleted of the β-Hexosaminidase A iso-enzyme, remain asymptomatic up to 1 year of age because of a metabolic bypass by neuraminidase(s. These enzymes remove a sialic acid residue converting GM2 to GA2, which is further degraded by the still intact β-Hexosaminidase B iso-enzyme into lactosylceramide. A previously identified ganglioside metabolizing neuraminidase, Neu4, is abundantly expressed in the mouse brain and has activity against gangliosides like GM2 in vitro. Neu4−/− mice showed increased GD1a and decreased GM1 ganglioside in the brain suggesting the importance of the Neu4 in ganglioside catabolism. Mice with targeted disruption of both HexA and Neu4 genes showed accumulating GM2 ganglioside and epileptic seizures with 40% penetrance, indicating that the neuraminidase Neu4 is a modulatory gene, but may not be the only neuraminidase contributing to the metabolic bypass in HexA−/− mice. Therefore, we elucidated the biological role of neuraminidase-1 in ganglioside degradation in mouse. Analysis of HexA−/−Neu1−/− and HexA−/−Neu4−/−Neu1−/− mice models showed significant contribution of neuraminidase-1 on B-series ganglioside degradation in the brain. Therefore, we speculate that other neuraminidase/neuraminidases such as Neu2 and/or Neu3 might be also involved in the ganglioside degradation pathway in HexA−/− mice.

  15. Aging in CTBN modified epoxy resin stocks

    International Nuclear Information System (INIS)

    Creed, K.E. Jr.

    1979-01-01

    The cause of degradation in the glass transition temperature (T/sub G/) of a partially crystallized polymer was investigated. Sample epoxy resin filled capacitors were cured at 90 0 C for 24 hours, then stored at room atmospheric conditions. These showed typical degradation in T/sub G/ after storage for one month. One set of epoxy resin castings was stored at room atmosphere and another set was stored in a dry box at 0% relative humidity and 27 0 C. The samples at room atmospheric conditions showed typical degradation in T/sub G/, while the T/sub G/ for those stored in the dry box increased. Further tests were then made on epoxy resin castings at various curing temperatures and times at both room atmosphere and 0% humidity. Resulting data indicated that absorption of moisture during storage was the predominant cause of T/sub G/ degradation, with stress relaxation another, though smaller, contributing factor

  16. Anatomical significance of a posterior horn of medial meniscus: the relationship between its radial tear and cartilage degradation of joint surface

    Directory of Open Access Journals (Sweden)

    Kan Akinori

    2010-01-01

    Full Text Available Abstract Background Traumatic injury and surgical meniscectomy of a medial meniscus are known to cause subsequent knee osteoarthritis. However, the difference in the prevalence of osteoarthritis caused by the individual type of the medial meniscal tear has not been elucidated. The aim of this study was to investigate what type of tear is predominantly responsible for the degradation of articular cartilage in the medial compartment of knee joints. Methods Five hundred and forty eight cadaveric knees (290 male and 258 female were registered in this study. The average age of cadavers at death was 78.8 years old (range: 52-103 years. The knees were macroscopically examined and their medial menisci were classified into four groups according to types of tears: "no tear", "radial tear of posterior horn", "other types of tear" and "worn-out meniscus" groups. The severity of cartilage degradation in their medial compartment of knee joints was evaluated using the international cartilage repair society (ICRS grading system. We statistically compared the ICRS grades among the groups using Mann-Whitney U test. Results The knees were assigned into the four groups: 416 "no tear" knees, 51 "radial tear of posterior horn" knees, 71 "other types of tear" knees, and 10 "worn-out meniscus" knees. The knees with substantial meniscal tears showed the severer ICRS grades of cartilage degradation than those without meniscal tears. In addition, the ICRS grades were significantly severer in the "radial tear of posterior horn" group than in the "other types of tear" group, suggesting that the radial tear of posterior horn in the medial meniscus is one of the risk factors for cartilage degradation of joint surface. Conclusions We have clarified the relationship between the radial tear of posterior horn in the medial meniscus and the severer grade of cartilage degradation. This study indicates that the efforts should be made to restore the anatomical role of the posterior

  17. Antioxidant-rich leaf extract of Barringtonia racemosa significantly alters the in vitro expression of genes encoding enzymes that are involved in methylglyoxal degradation III.

    Science.gov (United States)

    Kong, Kin Weng; Abdul Aziz, Azlina; Razali, Nurhanani; Aminuddin, Norhaniza; Mat Junit, Sarni

    2016-01-01

    Barringtonia racemosa is a medicinal plant belonging to the Lecythidaceae family. The water extract of B. racemosa leaf (BLE) has been shown to be rich in polyphenols. Despite the diverse medicinal properties of B. racemosa, information on its major biological effects and the underlying molecular mechanisms are still lacking. In this study, the effect of the antioxidant-rich BLE on gene expression in HepG2 cells was investigated using microarray analysis in order to shed more light on the molecular mechanism associated with the medicinal properties of the plant. Microarray analysis showed that a total of 138 genes were significantly altered in response to BLE treatment (p Degradation III followed by VDR/RXR activation, TR/RXR activation, PXR/RXR activation and gluconeogenesis. The expression of genes that encode for enzymes involved in methylglyoxal degradation (ADH4, AKR1B10 and AKR1C2) and glycolytic process (ENO3, ALDOC and SLC2A1) was significantly regulated. Owing to the Warburg effect, aerobic glycolysis in cancer cells may increase the level of methylglyoxal, a cytotoxic compound. BLE has the potential to be developed into a novel chemopreventive agent provided that the cytotoxic effects related to methylglyoxal accumulation are minimized in normal cells that rely on aerobic glycolysis for energy supply.

  18. Oxidation of resin acids in colophony (rosin) and its implications for patch testing.

    Science.gov (United States)

    Sadhra, S; Foulds, I S; Gray, C N

    1998-08-01

    Commercial preparations of colophony (rosin) used for patch testing are made from unmodified rosin in pet. and may be stored for some considerable time before being used. This would be satisfactory if the composition and dermatological activity of the preparations were both reproducible and stable, but investigations by the authors have shown that the resin acids undergo progressive and substantial oxidation and that the dermatological activity of the preparations increases significantly with time. This may be a cause of inconsistent patch test results unless the composition can be stabilized. Gas liquid chromatography (GLC) analysis of a raw rosin sample and its commercial patch test preparation has shown that they both contained the same resin acids, but the concentration of the abietic type resin acids was found to be lower in the patch test preparations. The degradation of resin acids is due to their atmospheric oxidation, which may occur during the preparation and storage of the commercial rosin patch test preparation. The susceptibility of individual resin acids to atmospheric oxidation was demonstrated by analysing a sample of raw Portuguese gum rosin, which was then left exposed to air and light. Most of the resin acids were found to undergo oxidation at a rate which gradually diminished. More importantly, it is presumed that the concentration of oxidized resin acids increased correspondingly, and these have been shown to be more dermatologically active than the unoxidised resin acids. The rate of decrease of resin acid concentration was found to be in the following order: neoabietic>levopimaric and palustric>abietic>dehydroabetic acid. The pimaric type resin acids were found to be relatively inert to atmospheric oxidation when compared with the abietic type resin acids. Patch testing with the resulting partly oxidized Portuguese rosin produced positive reactions at a 35% higher frequency than the raw Portuguese rosin. The study demonstrates that the

  19. Antioxidant-rich leaf extract of Barringtonia racemosa significantly alters the in vitro expression of genes encoding enzymes that are involved in methylglyoxal degradation III

    Directory of Open Access Journals (Sweden)

    Kin Weng Kong

    2016-08-01

    Full Text Available Background Barringtonia racemosa is a medicinal plant belonging to the Lecythidaceae family. The water extract of B. racemosa leaf (BLE has been shown to be rich in polyphenols. Despite the diverse medicinal properties of B. racemosa, information on its major biological effects and the underlying molecular mechanisms are still lacking. Methods In this study, the effect of the antioxidant-rich BLE on gene expression in HepG2 cells was investigated using microarray analysis in order to shed more light on the molecular mechanism associated with the medicinal properties of the plant. Results Microarray analysis showed that a total of 138 genes were significantly altered in response to BLE treatment (p < 0.05 with a fold change difference of at least 1.5. SERPINE1 was the most significantly up-regulated gene at 2.8-fold while HAMP was the most significantly down-regulated gene at 6.5-fold. Ingenuity Pathways Analysis (IPA revealed that “Cancer, cell death and survival, cellular movement” was the top network affected by the BLE with a score of 44. The top five canonical pathways associated with BLE were Methylglyoxal Degradation III followed by VDR/RXR activation, TR/RXR activation, PXR/RXR activation and gluconeogenesis. The expression of genes that encode for enzymes involved in methylglyoxal degradation (ADH4, AKR1B10 and AKR1C2 and glycolytic process (ENO3, ALDOC and SLC2A1 was significantly regulated. Owing to the Warburg effect, aerobic glycolysis in cancer cells may increase the level of methylglyoxal, a cytotoxic compound. Conclusions BLE has the potential to be developed into a novel chemopreventive agent provided that the cytotoxic effects related to methylglyoxal accumulation are minimized in normal cells that rely on aerobic glycolysis for energy supply.

  20. Review: Resin Composite Filling

    OpenAIRE

    Desmond Ng; Jimmy C. M. Hsiao; Keith C. T. Tong; Harry Kim; Yanjie Mai; Keith H. S. Chan

    2010-01-01

    The leading cause of oral pain and tooth loss is from caries and their treatment include restoration using amalgam, resin, porcelain and gold, endodontic therapy and extraction. Resin composite restorations have grown popular over the last half a century because it can take shades more similar to enamel. Here, we discuss the history and use of resin, comparison between amalgam and resin, clinical procedures involved and finishing and polishing techniques for resin restoration. Although resin ...

  1. Significant visible-light photocatalytic enhancement in Rhodamine B degradation of silver orthophosphate via the hybridization of N-doped graphene and poly(3-hexylthiophene)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanlin, E-mail: zhangyl@scnu.edu.cn; Xie, Churu; Gu, Feng Long, E-mail: Gu@scnu.edu.cn; Wu, Honghai; Guo, Qiang

    2016-09-05

    Highlights: • The Ag{sub 3}PO{sub 4}/NG/P3HT composites were synthesized via a facile method. • The Ag{sub 3}PO{sub 4}/NG/P3HT composites exhibit excellent photocatalytic activity for RhB degradation. • The kinetic constant of Ag{sub 3}PO{sub 4}/NG/P3HT is more than 6 times of pristine Ag{sub 3}PO{sub 4}. • The composites show better recyclability and stability than pristine Ag{sub 3}PO{sub 4}. - Abstract: Organic pollutants as typical water contaminants are potentially harmful to human health. In this study, we suggested that the novel Ag{sub 3}PO{sub 4}/N-doped graphene (NG)/Poly(3-hexylthiophene) (P3HT) composites can remove the organic dye Rhodamine B (RhB) from water. This Ag{sub 3}PO{sub 4}-based photocatalyst was synthesized via a facile method and subsequently characterized by XRD, SEM, TEM, XPS, Raman spectroscopy, PL spectroscopy, and UV–vis DRS. The photocatalytic activity of Ag{sub 3}PO{sub 4}/NG/P3HT composites is significantly higher than that of pristine Ag{sub 3}PO{sub 4}, Ag{sub 3}PO{sub 4}/NG, and Ag{sub 3}PO{sub 4}/P3HT for RhB degradation under visible light irradiation, especially the kinetic constant of Ag{sub 3}PO{sub 4}/NG/P3HT is more than 6 times of pristine Ag{sub 3}PO{sub 4}. The reactive oxygen species trapping experiments indicate that the degradation of RhB over the Ag{sub 3}PO{sub 4}/NG/P3HT composites mainly results from the holes oxidation and superoxide radical reduction. Besides, Ag{sub 3}PO{sub 4}/NG/P3HT composites exhibit better recyclability and stability than pristine Ag{sub 3}PO{sub 4}. Furthermore, the photocatalytic mechanism of Ag{sub 3}PO{sub 4}/NG/P3HT composites for RhB degradation under visible light was proposed as the synergistic effect of irradiated Ag{sub 3}PO{sub 4}, P3HT and NG sheets on the effective separation of photogenerated electron-hole pairs, and the enhancement of visible light absorbance.

  2. Significant visible-light photocatalytic enhancement in Rhodamine B degradation of silver orthophosphate via the hybridization of N-doped graphene and poly(3-hexylthiophene)

    International Nuclear Information System (INIS)

    Zhang, Yanlin; Xie, Churu; Gu, Feng Long; Wu, Honghai; Guo, Qiang

    2016-01-01

    Highlights: • The Ag 3 PO 4 /NG/P3HT composites were synthesized via a facile method. • The Ag 3 PO 4 /NG/P3HT composites exhibit excellent photocatalytic activity for RhB degradation. • The kinetic constant of Ag 3 PO 4 /NG/P3HT is more than 6 times of pristine Ag 3 PO 4 . • The composites show better recyclability and stability than pristine Ag 3 PO 4 . - Abstract: Organic pollutants as typical water contaminants are potentially harmful to human health. In this study, we suggested that the novel Ag 3 PO 4 /N-doped graphene (NG)/Poly(3-hexylthiophene) (P3HT) composites can remove the organic dye Rhodamine B (RhB) from water. This Ag 3 PO 4 -based photocatalyst was synthesized via a facile method and subsequently characterized by XRD, SEM, TEM, XPS, Raman spectroscopy, PL spectroscopy, and UV–vis DRS. The photocatalytic activity of Ag 3 PO 4 /NG/P3HT composites is significantly higher than that of pristine Ag 3 PO 4 , Ag 3 PO 4 /NG, and Ag 3 PO 4 /P3HT for RhB degradation under visible light irradiation, especially the kinetic constant of Ag 3 PO 4 /NG/P3HT is more than 6 times of pristine Ag 3 PO 4 . The reactive oxygen species trapping experiments indicate that the degradation of RhB over the Ag 3 PO 4 /NG/P3HT composites mainly results from the holes oxidation and superoxide radical reduction. Besides, Ag 3 PO 4 /NG/P3HT composites exhibit better recyclability and stability than pristine Ag 3 PO 4 . Furthermore, the photocatalytic mechanism of Ag 3 PO 4 /NG/P3HT composites for RhB degradation under visible light was proposed as the synergistic effect of irradiated Ag 3 PO 4 , P3HT and NG sheets on the effective separation of photogenerated electron-hole pairs, and the enhancement of visible light absorbance.

  3. Resin Characterization

    Science.gov (United States)

    2015-06-01

    to see plastic deformation of the surface. 8.1.4.3 Density: Density using the Archimedes principle (ASTM D 792). 8.1.4.4 Density as a Function of...the cure and postcure, quickly cool the sample to 0 °C or lower the temperature to quench the reaction, and then ramp the temperature at 5 °C/min to...prepared by pouring 10 g of resin into a 30-mL screw-cap scintillation vial and adding appropriate amounts of initiator, catalyst, and inhibitor

  4. Bed Degradation and Sediment Export from the Missouri River after Dam Construction and River Training: Significance to Lower Mississippi River Sediment Loads

    Science.gov (United States)

    Blum, M. D.; Viparelli, E.; Sulaiman, Z. A.; Pettit, B. S.

    2016-12-01

    More than 40,000 dams have been constructed in the Mississippi River drainage basin, which has had a dramatic impact on suspended sediment load for the Mississippi delta. The most significant dams were constructed in the 1950s on the Missouri River in South Dakota, after which total suspended loads for the lower Mississippi River, some 2500 km downstream, were cut in half: gauging station data from the Missouri-Mississippi system show significant load reductions immediately after dam closure, followed by a continued downward trend since that time. The delta region is experiencing tremendous land loss in response to acceleration of global sea-level rise, and load reductions of this magnitude may place severe limits on mitigation efforts. Here we examine sediment export from the Missouri system due to bed scour. The US Army Corps of Engineers has compiled changes in river stage at constant discharge for 8 stations between the lowermost dam at Yankton, South Dakota and the Missouri-Mississippi confluence at St. Louis (a distance of 1250 river km), for the period 1930-2010, which we have updated to 2015. These data show two general reaches of significant bed degradation. The first extends from the last major dam at Yankton, South Dakota downstream 300 km to Omaha, Nebraska, where degradation in response to the dam exceeds 3 m. The second reach, with >2.5 m of degradation, occurs in and around Kansas City, Missouri, and has been attributed to river training activities. The reach between Omaha and Kansas City, as well as the lower Missouri below Kansas City, show River due to bed scour following dam construction and river training. This number equates to 20-25 million tons per year, which is sufficient to account for 30% of the total Missouri River load, and 15% of the total post-dam annual sediment load for the lower Mississippi River. For perspective, the quantity of sediment exported from the Missouri River due to bed scour is greater than the total load for all

  5. Ten-year Clinical Performance of Posterior Resin Composite Restorations.

    Science.gov (United States)

    Krämer, Norbert; Reinelt, Christian; Frankenberger, Roland

    2015-08-01

    To investigate the clinical behavior of two different resin-based restorative systems in Class II cavities in a controlled prospective split-mouth study over 10 years. Thirty patients received 68 resin composite restorations (Solobond M + Grandio: n = 36; Syntac + Tetric Ceram: n = 32) by one dentist in a private practice. 35% of cavities revealed no enamel at the bottom of the proximal box, 48% of cavities provided Grandio restoration suffered marginal fracture with exposed dentin and one Tetric Ceram restoration failed due to cusp fracture. After 10 years, Grandio showed higher surface roughness (p = 0.03) and less color match (p = 0.024; Mann-Whitney U-test). Molar restorations performed worse than premolar fillings regarding marginal integrity (4 and 10 years), filling integrity (4, 8, and 10 years), and tooth integrity (4, 8, and 10 years). The main reasons for degradation of resin composites were chipping and cracks in molar restorations after 8 years. Beyond the 4-year recall, marginal staining increased (43% bravo for stained margins at four years, 52% at 8 years, and 71% at 10 years). Tooth integrity deteriorated significantly due to more enamel cracks and chipping over time (9% at baseline and 89% after 10 years (p<0.05). Direct resin composite restorations performed satisfactorily over 10 years of clinical service.

  6. Effects of postcuring on mechanical properties of pultruded fiber-reinforced epoxy composites and the neat resin

    Science.gov (United States)

    Long, Edward R., Jr.; Long, Sheila Ann T.; Funk, Joan G.; Collins, William D.; Gray, Stephanie L.

    1989-01-01

    The effects of postcuring on mechanical properties of pultruded fiber-reinforced epoxy-resin composites have been investigated. Composites with carbon, glass, and aramid reinforcement fibers were individually studied. The epoxy was a commercially-available resin that was especially developed for pultrusion fabrication. The pultrusions were conducted at 400 F with postcures at 400, 450, 500, and 550 F. Measurements of the flexural, shear, and interlaminar fracture-toughness properties showed that significant postcuring can occur during the pultrusion process. All three mechanical properties were degraded by the higher (500 and 550 F) temperatures; photomicrographs suggest that the degradation was caused at the fiber-resin interface for all three fiber types.

  7. Bulk-Fill Resin Composites

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Havndrup-Pedersen, Cæcilie; Honoré, Daniel

    2015-01-01

    the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization...... for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low......-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk...

  8. Bending characteristics of resin concretes

    Directory of Open Access Journals (Sweden)

    Ribeiro Maria Cristina Santos

    2003-01-01

    Full Text Available In this research work the influence of composition and curing conditions in bending strength of polyester and epoxy concrete is analyzed. Various mixtures of resin and aggregates were considered in view of an optimal combination. The Taguchi methodology was applied in order to reduce the number of tests, and in order to evaluate the influence of various parameters in concrete properties. This methodology is very useful for the planning of experiments. Test results, analyzed by this methodology, shown that the most significant factors affecting bending strength properties of resin concretes are the type of resin, resin content and charge content. An optimal formulation leading to a maximum bending strength was achieved in terms of material parameters.

  9. Epoxy hydantoins as matrix resins

    Science.gov (United States)

    Weiss, J.

    1983-01-01

    Tensile strength and fracture toughness of castings of the hydantoin resins cured with methylenedianiline are significantly higher than MY 720 control castings. Water absorption of an ethyl, amyl hydantoin formulation is 2.1 percent at equilibrium and Tg's are about 160 C, approximately 15 deg below the final cure temperature. Two series of urethane and ester-extended hydantoin epoxy resins were synthesized to determine the effect of crosslink density and functional groups on properties. Castings cured with methylenedianiline or with hexahydrophthalic anhydride were made from these compounds and evaluated. The glass transition temperatures, tensile strengths and moduli, and fracture toughness values were all much lower than that of the simple hydantoin epoxy resins. Using a methylene bishydantoin epoxy with a more rigid structure gave brittle, low-energy fractures, while a more flexible, ethoxy-extended hydantoin epoxy resin gave a very low Tg.

  10. Immobilization of spent resin with epoxy resin

    International Nuclear Information System (INIS)

    Gultom, O.; Suryanto; Sayogo; Ramdan

    1997-01-01

    immobilization of spent resin using epoxy resin has been conducted. The spent resin was mixtured with epoxy resin in variation of concentration, i.e., 30, 40, 50, 60, 70 weight percent of spent resin. The mixture were pour into the plastic tube, with a diameter of 40 mm and height of 40 mm. The density, compressive strength and leaching rate were respectively measured by quanta chrome, paul weber apparatus and gamma spectrometer. The results showed that the increasing of waste concentration would be decreased the compressive strength, and increased density by immobilized waste. The leaching rate of 137 Cs from waste product was not detected in experiment (author)

  11. Karakteristik Komposit Resin Berkemampuan Mengalir

    Directory of Open Access Journals (Sweden)

    Bambang Irawan

    2015-10-01

    Full Text Available The use of resin composites as posterior restoratives has markedly increased over the past decade. The patients demand for better esthetics, concerns related to possible mercury toxicity from amalgam and improvements in resin composite materials have significantly contributed the popularity of these materials. Early problems related to composites included excessive wear, less of anatomic form, post operative sensitivity, secondary caries and marginal leakage. Marginal adaptation still remains an unavoidable problem for composite restoration, especially at the gingival wall of cervical or Class II restoration. In an attempt to improve marginal sealing, many techniques and lining materials have been designed. To reduce stress generated by polymerization shrinkage, applying and curing of resin composites in layers is often recommended. Using a thick adhesive layer or low-viscosity resin may, due to its elastic properties, serve as a flexible intermediate layer and compensate for the polymerization stress created in resin composite. Flowable composites were created by retaining the same small particle size of traditional hybrid composite but reducing the filler content and allowing the increased resin to reduce the viscosity of the mixture. Flowable composites were introduced in 1996 as liners, fissure sealants and also in tunnel preparations. They have been suggested for Class I, II, III and V cavity restorations, preventive resin restorations and composite, porcelain and amalgam repairing. Their usage as a liner under high filled resins in posterior restorations has been shown to improve the adaptation of composites and effectively achieve clinically acceptable results. This article attempts to give a broad characteristics of different types of flowable composites. 

  12. Bond strength of resin-resin interfaces contaminated with saliva and submitted to different surface treatments.

    Science.gov (United States)

    Furuse, Adilson Yoshio; da Cunha, Leonardo Fernandes; Benetti, Ana Raquel; Mondelli, José

    2007-12-01

    The purpose of this study was to investigate the effect of different surface treatments on shear bond strength of saliva-contaminated resin-resin interfaces. Flat resin surfaces were fabricated. In the control group, no contamination or surface treatment was performed. The resin surfaces of the experimental groups were contaminated with saliva and air-dried, and then submitted to: (G1) rinsing with water and drying; (G2) application of an adhesive system; (G3) rinsing and drying, abrasion with finishing disks, etching and application of adhesive system; (G4) rinsing and drying, etching, application of silane and adhesive system. Resin cylinders were placed over the treated surfaces. The specimens were stored in water or ethanol. Shear bond strength tests were performed and the mode of failure was evaluated. Data were submitted to two-way ANOVA and Dunnett T3 test. Contamination of resin-resin interfaces with saliva significantly reduced shear strength, especially after prolonged storage (presin increments.

  13. Nanosilica Modification of Elastomer-Modified VARTM Epoxy Resins for Improved Resin and Composite Toughness

    National Research Council Canada - National Science Library

    Robinette, Jason; Bujanda, Andres; DeSchepper, Daniel; Dibelka, Jessica; Costanzo, Philip; Jensen, Robert; McKnight, Steven

    2007-01-01

    Recent publications have reported a synergy between rubber and silica in modified epoxy resins that results in significantly improved fracture toughness without reductions in other material properties...

  14. Resin elasticity and the strengthening of all-ceramic restorations.

    Science.gov (United States)

    Addison, O; Marquis, P M; Fleming, G J P

    2007-06-01

    Resin luting of all-ceramic restorations results in increased performance; however, the strengthening mechanism and the role of the mechanical properties of the resin are not fully understood. The hypothesis tested is that ceramic strength enhancement is dependent on the elastic modulus of the resin. Three-point flexural moduli of a flowable, luting, and hybrid composite resin were characterized. Two hundred forty porcelain discs were air-abraded. One group acted as a control, and 3 additional groups were coated with 120 +/- 20 microm of each resin prior to bi-axial flexure testing. All resins significantly increased in mean strength, and the associated strength increase was related to the elastic modulus of the resin (R(2) = 0.9885), so the hypothesis was accepted. The combination of Poisson constraint and the creation of a resin-inter-penetrating layer sensitive to the elastic modulus of the resin may provide an explanation of the strengthening mechanism.

  15. Surface Charges and Shell Crosslinks Each Play Significant Roles in Mediating Degradation, Biofouling, Cytotoxicity and Immunotoxicity for Polyphosphoester-based Nanoparticles

    Science.gov (United States)

    Elsabahy, Mahmoud; Zhang, Shiyi; Zhang, Fuwu; Deng, Zhou J.; Lim, Young H.; Wang, Hai; Parsamian, Perouza; Hammond, Paula T.; Wooley, Karen L.

    2013-11-01

    The construction of nanostructures from biodegradable precursors and shell/core crosslinking have been pursued as strategies to solve the problems of toxicity and limited stability, respectively. Polyphosphoester (PPE)-based micelles and crosslinked nanoparticles with non-ionic, anionic, cationic, and zwitterionic surface characteristics for potential packaging and delivery of therapeutic and diagnostic agents, were constructed using a quick and efficient synthetic strategy, and importantly, demonstrated remarkable differences in terms of cytotoxicity, immunotoxicity, and biofouling properties, as a function of their surface characteristics and also with dependence on crosslinking throughout the shell layers. For instance, crosslinking of zwitterionic micelles significantly reduced the immunotoxicity, as evidenced from the absence of secretions of any of the 23 measured cytokines from RAW 264.7 mouse macrophages treated with the nanoparticles. The micelles and their crosslinked analogs demonstrated lower cytotoxicity than several commercially-available vehicles, and their degradation products were not cytotoxic to cells at the range of the tested concentrations. PPE-nanoparticles are expected to have broad implications in clinical nanomedicine as alternative vehicles to those involved in several of the currently available medications.

  16. Review: Resin Composite Filling

    Directory of Open Access Journals (Sweden)

    Desmond Ng

    2010-02-01

    Full Text Available The leading cause of oral pain and tooth loss is from caries and their treatment include restoration using amalgam, resin, porcelain and gold, endodontic therapy and extraction. Resin composite restorations have grown popular over the last half a century because it can take shades more similar to enamel. Here, we discuss the history and use of resin, comparison between amalgam and resin, clinical procedures involved and finishing and polishing techniques for resin restoration. Although resin composite has aesthetic advantages over amalgam, one of the major disadvantage include polymerization shrinkage and future research is needed on reaction kinetics and viscoelastic behaviour to minimize shrinkage stress.

  17. Review: Resin Composite Filling

    Science.gov (United States)

    Chan, Keith H. S.; Mai, Yanjie; Kim, Harry; Tong, Keith C. T.; Ng, Desmond; Hsiao, Jimmy C. M.

    2010-01-01

    The leading cause of oral pain and tooth loss is from caries and their treatment include restoration using amalgam, resin, porcelain and gold, endodontic therapy and extraction. Resin composite restorations have grown popular over the last half a century because it can take shades more similar to enamel. Here, we discuss the history and use of resin, comparison between amalgam and resin, clinical procedures involved and finishing and polishing techniques for resin restoration. Although resin composite has aesthetic advantages over amalgam, one of the major disadvantage include polymerization shrinkage and future research is needed on reaction kinetics and viscoelastic behaviour to minimize shrinkage stress.

  18. 40 CFR 721.5908 - Modified phenolic resin (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified phenolic resin (generic). 721... Substances § 721.5908 Modified phenolic resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as modified phenolic resin (PMN P...

  19. 40 CFR 721.2673 - Aromatic epoxide resin (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aromatic epoxide resin (generic). 721... Substances § 721.2673 Aromatic epoxide resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aromatic epoxide resin (PMN P...

  20. 40 CFR 721.9499 - Modified silicone resin.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified silicone resin. 721.9499... Substances § 721.9499 Modified silicone resin. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a modified silicone resin (PMN P-96-1649) is...

  1. 40 CFR 721.4380 - Modified hydrocarbon resin.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified hydrocarbon resin. 721.4380... Substances § 721.4380 Modified hydrocarbon resin. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a modified hydrocarbon resin (P-91-1418) is...

  2. 40 CFR 721.5905 - Modified phenolic resin (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified phenolic resin (generic). 721... Substances § 721.5905 Modified phenolic resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a modified phenolic resin (PMN...

  3. 40 CFR 721.2755 - Cycloaliphatic epoxy resin (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Cycloaliphatic epoxy resin (generic... Substances § 721.2755 Cycloaliphatic epoxy resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as cycloaliphatic epoxy resin (PMN...

  4. Resin-Powder Dispenser

    Science.gov (United States)

    Standfield, Clarence E.

    1994-01-01

    Resin-powder dispenser used at NASA's Langley Research Center for processing of composite-material prepregs. Dispenser evenly distributes powder (resin polymer and other matrix materials in powder form) onto wet uncured prepregs. Provides versatility in distribution of solid resin in prepreg operation. Used wherever there is requirement for even, continuous distribution of small amount of powder.

  5. In vitro two-body wear of inlay-onlay composite resin restoratives.

    Science.gov (United States)

    Burgoyne, A R; Nicholls, J I; Brudvik, J S

    1991-02-01

    Inlay-onlay composite resin restorations have been introduced to the profession as alternatives to amalgam and direct composite resins. Two-body wear testing was performed on three inlay-onlay resins and one direct composite resins using a machine designed to produce sliding wear. The composite resins were opposed by human enamel, type III gold alloy, and porcelain. Of the investigated materials, the homogeneously microfilled inlay-onlay material showed significantly less wear. The direct composite resin showed significantly the greatest wear. The hybrid inlay-onlay resins showed intermediate wear. The hybrid inlay-onlay resins and the direct composite (small particle, heavily filled) resin created wear tracks in the opposing surfaces while the homogeneous microfill inlay-onlay resin did not. The depth of the observed wear tracks in the opposing surface was sufficiently substantial to warrant further investigation into the wear of materials that oppose composite resin restorations.

  6. Effect of proximal box elevation with resin composite on marginal quality of resin composite inlays in vitro.

    Science.gov (United States)

    Roggendorf, Matthias J; Krämer, Norbert; Dippold, Christoph; Vosen, Vera E; Naumann, Michael; Jablonski-Momeni, Anahita; Frankenberger, Roland

    2012-12-01

    To evaluate marginal quality and resin-resin transition of lab made resin composite inlays in deep proximal cavities with and without 3 mm proximal box elevation (PBE) using resin composites before and after thermo-mechanical loading (TML). MOD cavities with one proximal box beneath the cementoenamel junction were prepared in 40 extracted human third molars. Proximal boxes ending in dentine were elevated 3 mm with different resin composites (G-Cem, Maxcem Elite as self-adhesive resin cements and Clearfil Majesty Posterior as restorative resin composite in one or three layers bonded with AdheSE), or left untreated. Clearfil Majesty Posterior inlays were luted with Syntac and Variolink II (n = 8). Marginal quality as well as the PBE-composite inlay interface was analyzed under an SEM using epoxy resin replicas before and after thermomechanical loading (100,000 × 50 N and 2500 thermocylces between +5 °C and +55 °C). Bonding resin composite inlays directly to dentine showed similar amounts of gap-free margins in dentine compared to PBE applied in three consecutive layers (p > 0.05). The groups with self-adhesive resin cements for PBE exhibited significantly more gaps in dentine (p < 0.05). With layered resin composite, PBE is effective in indirect resin composite bonding to deep proximal boxes. Self-adhesive resin cements are not suitable for this indication. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Ponderosa pine resin defenses and growth: metrics matter.

    Science.gov (United States)

    Hood, Sharon; Sala, Anna

    2015-11-01

    Bark beetles (Coleoptera: Curculionidae, Scolytinae) cause widespread tree mortality in coniferous forests worldwide. Constitutive and induced host defenses are important factors in an individual tree's ability to survive an attack and in bottom-up regulation of bark beetle population dynamics, yet quantifying defense levels is often difficult. For example, in Pinus spp., resin flow is important for resistance to bark beetles but is extremely variable among individuals and within a season. While resin is produced and stored in resin ducts, the specific resin duct metrics that best correlate with resin flow remain unclear. The ability and timing of some pine species to produce induced resin is also not well understood. We investigated (i) the relationships between ponderosa pine (Pinus ponderosa Lawson & C. Lawson) resin flow and axial resin duct characteristics, tree growth and physiological variables, and (ii) if mechanical wounding induces ponderosa pine resin flow and resin ducts in the absence of bark beetles. Resin flow increased later in the growing season under moderate water stress and was highest in faster growing trees. The best predictors of resin flow were nonstandardized measures of resin ducts, resin duct size and total resin duct area, both of which increased with tree growth. However, while faster growing trees tended to produce more resin, models of resin flow using only tree growth were not statistically significant. Further, the standardized measures of resin ducts, density and duct area relative to xylem area, decreased with tree growth rate, indicating that slower growing trees invested more in resin duct defenses per unit area of radial growth, despite a tendency to produce less resin overall. We also found that mechanical wounding induced ponderosa pine defenses, but this response was slow. Resin flow increased after 28 days, and resin duct production did not increase until the following year. These slow induced responses may allow

  8. Diterpene resin acids in conifers.

    Science.gov (United States)

    Keeling, Christopher I; Bohlmann, Jörg

    2006-11-01

    Diterpene resin acids are a significant component of conifer oleoresin, which is a viscous mixture of terpenoids present constitutively or inducibly upon herbivore or pathogen attack and comprises one form of chemical resistance to such attacks. This review focuses on the recent discoveries in the chemistry, biosynthesis, molecular biology, regulation, and biology of these compounds in conifers.

  9. Electrodialytic decontamination of spent ion exchange resins

    International Nuclear Information System (INIS)

    Nott, B.R.

    1982-01-01

    Development of a novel electrodialytic decontamination process for the selective removal of radioactive Cs from spent ion exchange resins containing large amounts of Li is described. The process involves passage of a dc electric current through a bed of the spent ion exchange resin in a specially designed electrodialytic cell. The radiocesium so removed from a volume of the spent resin is concentrated onto a much smaller volume of a Cs selective sorbent to achieve a significant radioactive waste volume reduction. Technical feasibility of the electrodialytic resin decontamination process has been demonstrated on a bench scale with a batch of simulated spent ion exchange resin and using potassium cobalt ferrocyanide as the Cs selective sorbent. A volume reduction factor between 10 and 17 has been estimated. The process appears to be economically attractive. Improvements in process economics can be expected from optimization of the process. Other possible applications of the EDRD process have been identified

  10. Mechanistic understanding of fouling of protein A chromatography resin.

    Science.gov (United States)

    Pathak, Mili; Rathore, Anurag S

    2016-08-12

    This paper aims to provide a thorough understanding of how fouling of Protein A resin takes place. Binding and mass transport properties of widely used agarose-based Protein A resin, MabSelect SuRe™, have been examined to understand the mechanism of resin fouling. There could be various factors that impact resin fouling. These include product/impurity build-up due to components in the feed material and ligand degradation due to the use of harsh buffers. To unravel their contributions, cycling studies were performed with and without product loading. The results presented in this paper provide a lucid understanding of the causative factors that limit Protein A chromatographic resin lifetime. The capacity fall for protein A resin at the end of 100th cycle due to use of feed material was found to be five times greater than that without using feed material. Compared to the fresh resin, the cycled resin samples shows 24% reduction in particle porosity and 51% reduction in pore mass transfer coefficient. Transmission electron microscopy (TEM) was used to qualitatively monitor accumulation of foulants on the cycled resin. Fouled resin sample contained a dense residue in the interior and exterior of resin particle both as a film at the bead surface and as granules. The surface activation energy increased five times in the case of fouled resin sample. The major event in fouling was identified as the non-specific adsorption of the feed material components on resin, signaling that pore diffusion is the rate limiting step. It is anticipated that these findings will assist in development of a more robust and economical downstream manufacturing process for monoclonal antibody purification. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Raman microspectroscopic studies of amber resins with insect inclusions

    Science.gov (United States)

    Edwards, Howell G. M.; Farwell, Dennis W.; Villar, Susana E. Jorge

    2007-12-01

    Raman microscope spectra of specimens of Baltic and Mexican amber resins containing insect inclusions have been analysed using near-infrared excitation to assess the potential for discrimination between the keratotic remains of the insects and the terpenoid matrix. For the Mexican amber specimen the insect spectra exhibit evidence of significant protein degradation compared with the insect remains in the Baltic amber specimen. In both cases the Raman spectra of the insect remains are still distinguishable from the amber resins. Despite its better preservation, however, no spectra could be obtained from the inside of the larger insect preserved in the Baltic amber in agreement with the observation that most insect inclusions in amber are hollow. It is noted that the Mexican amber insect is located adjacent to a large gas bubble in the amber matrix, to which the observed degradation of the insect and its poor state of preservation are attributed. It is concluded that Raman spectra of insect inclusions can provide useful information about the chemical composition of the remains and that confocal microscopy is particularly advantageous in this respect.

  12. Solidification of ion exchange resin wastes

    International Nuclear Information System (INIS)

    1982-08-01

    Solidification media investigated included portland type I, portland type III and high alumina cements, a proprietary gypsum-based polymer modified cement, and a vinyl ester-styrene thermosetting plastic. Samples formulated with hydraulic cement were analyzed to investigate the effects of resin type, resin loading, waste-to-cement ratio, and water-to-cement ratio. The solidification of cation resin wastes with portland cement was characterized by excessive swelling and cracking of waste forms, both after curing and during immersion testing. Mixed bed resin waste formulations were limited by their cation component. Additives to improve the mechanical properties of portland cement-ion exchange resin waste forms were evaluated. High alumina cement formulations dislayed a resistance to deterioration of mechanical integrity during immersion testing, thus providing a significant advantage over portland cements for the solidification of resin wastes. Properties of cement-ion exchange resin waste forms were examined. An experiment was conducted to study the leachability of 137 Cs, 85 Sr, and 60 Co from resins modified in portland type III and high alumina cements. The cumulative 137 Cs fraction release was at least an order of magnitude greater than that of either 85 Sr or 60 Co. Release rates of 137 Cs in high alumina cement were greater than those in portland III cement by a factor of two.Compressive strength and leach testing were conducted for resin wastes solidified with polymer-modified gypsum based cement. 137 Cs, 85 Sr, and 60 Co fraction releases were about one, two and three orders of magnitude higher, respectively, than in equivalent portland type III cement formulations. As much as 28.6 wt % dry ion exchange resin was successfully solidified using vinyl ester-styrene compared with a maximum of 25 wt % in both portland and gypsum-based cement

  13. [Effect of a chemical primer on the bond strength of a zirconia ceramic with self-adhesive resin cement].

    Science.gov (United States)

    Zhang, Hong; Jing, Ye; Nie, Rongrong; Meng, Xiangfeng

    2015-10-01

    To evaluate the bond strength and durability of a self-adhesive resin cement with a zirconia ceramic pretreated by a zirconia primer. Zirconia ceramic (Vita Inceram YZ) plates with a thickness of 2.5 mm were fired, polished, and then cleaned. Half of the polished ceramic plates were sandblasted with 50 μm alumina particles at 0.3 MPa for 20 s. The surface compound weight ratios were measured via X-ray fluorescence microscopy. The polished and sandblasted ceramic plates were directly bonded with self-adhesive resin cement (Biscem) or were pretreated by a zirconia primer (Z Primer Plus) before bonding with Biscem. The specimens of each test group were divided into two subgroups (n=10) and subjected to the shear test after 0 and 10,000 thermal cycles. The data were analyzed via three-way ANOVA. After air abrasion, 8.27% weight ratio of alumina attached to the zirconia surface. Compared with air abrasion, primer treatment more significantly improved the primary resin bond strength of the zirconia ceramic. The primary resin bond strength of the zirconia ceramic with no primer treatment was not affected by thermocycling (P>0.05). However, the primary resin bond strength of the zirconia ceramic with primer treatment was significantly decreased by thermocycling (Presin bond strengths of zirconia ceramics. However, the bond interface of the primer is not stable and rapidly degraded during thermocycling.

  14. Modification of bifunctional epoxy resin using CO{sub 2} fixation process and nanoclay

    Energy Technology Data Exchange (ETDEWEB)

    Khoshkish, Morteza; Bouhendi, Hosein, E-mail: H.boohendi@ippi.ac.ir; Vafayan, Mehdi

    2014-10-15

    A bifunctional epoxy resin was modified by using a CO{sub 2} fixation solution process in the presence of tetra n-butyl ammonium bromide (TBAB) as catalyst and the modified treated resin was treated by cloisite 30B as nano additive. The Unmodified epoxy resin (UME), CO{sub 2} fixated modified epoxy resin (CFME), and CFME/clay nano composite (CFMEN), were cured by diethylenetriamine (DETA). A cycloaliphatic compound as a reactive diluent was used to control the viscosity of high viscose CFME. The exfoliation of organoclay in UME and CFME was investigated by X-ray diffraction and activation energy was computed using the advanced integral isoconversional method. The activation energy dependency demonstrated that the mechanism of UME curing did not change in the presence of nanoclay. In contrast, the CO{sub 2} fixation results showed a significant change in the activation energy dependency. The Thermal stability parameters include the initial degradation temperature (IDT), the temperature at the maximum rate of weight loss (T{sub max}), and the decomposition activation energy (E{sub d}) were determined by thermal gravimetry analysis. Dynamic mechanical thermal analysis measurements showed that the presence of organoclay in CFME increases the T{sub g} of nano composite in contrast to UME. The fracture roughness of UME, CFME and CFNE were determined by scanning electron microscope. The exfoliated UME/1%clay nanocomposite was confirmed by TEM image. - Highlights: • A new epoxy resin was synthesized using CO{sub 2} fixation reaction. • The synthesized epoxy resin was modified by an organo nano-clay. • CO{sub 2} fixation noticeably changed the curing mechanism. • CO{sub 2} fixation reaction consumes CO{sub 2} which is a harmful greenhouse gas.

  15. Modification of bifunctional epoxy resin using CO2 fixation process and nanoclay

    International Nuclear Information System (INIS)

    Khoshkish, Morteza; Bouhendi, Hosein; Vafayan, Mehdi

    2014-01-01

    A bifunctional epoxy resin was modified by using a CO 2 fixation solution process in the presence of tetra n-butyl ammonium bromide (TBAB) as catalyst and the modified treated resin was treated by cloisite 30B as nano additive. The Unmodified epoxy resin (UME), CO 2 fixated modified epoxy resin (CFME), and CFME/clay nano composite (CFMEN), were cured by diethylenetriamine (DETA). A cycloaliphatic compound as a reactive diluent was used to control the viscosity of high viscose CFME. The exfoliation of organoclay in UME and CFME was investigated by X-ray diffraction and activation energy was computed using the advanced integral isoconversional method. The activation energy dependency demonstrated that the mechanism of UME curing did not change in the presence of nanoclay. In contrast, the CO 2 fixation results showed a significant change in the activation energy dependency. The Thermal stability parameters include the initial degradation temperature (IDT), the temperature at the maximum rate of weight loss (T max ), and the decomposition activation energy (E d ) were determined by thermal gravimetry analysis. Dynamic mechanical thermal analysis measurements showed that the presence of organoclay in CFME increases the T g of nano composite in contrast to UME. The fracture roughness of UME, CFME and CFNE were determined by scanning electron microscope. The exfoliated UME/1%clay nanocomposite was confirmed by TEM image. - Highlights: • A new epoxy resin was synthesized using CO 2 fixation reaction. • The synthesized epoxy resin was modified by an organo nano-clay. • CO 2 fixation noticeably changed the curing mechanism. • CO 2 fixation reaction consumes CO 2 which is a harmful greenhouse gas

  16. A Study on Tensile Behavior and Water Uptake of Wood Powder-Composites Based on Epoxy and Unsaturated Polyester Resins

    OpenAIRE

    Amir hossein Pirayeshfar; M.Mahdi Jalili; Yahya Musavi

    2013-01-01

    In this study, two kinds of epoxy resins (i.e. high-viscosity and low-viscosity) as well as one polyester resin (orthophthalic grade) were selected and examined as pure resins and also as a polymeric matrix for producing wood-composites. In this study, tensile properties, water uptake, and degradation of samples in water were also investigated. The results show that addition of wood particles to the thermoset resins strongly impresses on their tensile behavior and water uptake. Tensile studie...

  17. Development of Green Resin Using Solid Waste Protein Soybean Curd “Tofu” Production

    Directory of Open Access Journals (Sweden)

    Sujito

    2010-10-01

    Full Text Available One of the most concerns associated with many commercially available composites is that they used of non-degradable resins and fibers that primarily made using non-degradable, petroleum-based chemicals as feed stock. These conditions will create a serious problem in term of waste disposal after end of their life. Unlike petroleum, plant based protein and starches are yearly renewable. These resins are increasingly developed for various applications as replacements for non-degradable petroleum based resins. In addition, these resins may be easily composted after their life. In this study, Soybean Pulp Hemi-cellulose (SPH was modified by cross-linking it with glutaraldehyde (GA. The modified SPH resins were characterized for its surface morphology, tensile and mass losses or biodegradability properties. The effect of GA on the surface morphology, tensile and biodegradability of the SPH resins were discussed. The SPH resins showed improved surface morphology and ductility. However, the increasing the GA content reduces the Young’s modulus of the SPH resins. The SPH resins exhibited fracture stress point and Young’s modulus maximum of and 3.02 MN/m2, respectively, and biodegradability of 40.42% after 30 days placed on the open air. These properties seem to be sufficient for developing green composites from the SPH resins reinforced with natural fiber for indoor structural applications

  18. Post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin

    International Nuclear Information System (INIS)

    Yap, A.U.J.

    1997-01-01

    This study examined the post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin using a digital microhardness tester. Change in hardness of these materials over a period of 6 months was compared to that of conventional glass ionomer cements and a composite resin. With the exception of the composite resin, all materials showed a significant increase in hardness over 24 h after their initial set. Dual-cure resin-modified glass ionomer cements showed decreased hardness with increased storage time in saline at 37 o C. Results suggest that the addition of resins to glass ionomer cements does not improve initial hardness and does not negate the acid-base reaction of conventional cements. Resin addition may, however, lead to increased water sorption and decreased hardness. (author)

  19. Effect of ultraviolet light irradiation on bonding of experimental composite resin artificial teeth.

    Science.gov (United States)

    Loyaga-Rendon, Paola G; Takahashi, Hidekazu; Iwasaki, Naohiko; Reza, Fazal

    2007-11-01

    The purpose of the present study was to evaluate how ultraviolet light (UV) irradiation using an ordinary UV sterilizer would affect the bonding of experimental composite resins to an autopolymerizing acrylic resin. To this end, three composite resins and one unfilled resin--of which the compositions were similar to commercial composite resin artificial teeth--were prepared as repair composites. Their shear bond strengths after UV irradiation for one to 60 minutes were significantly greater than those before UV irradiation regardless of composite resin type. Failure mode after UV irradiation for one to 60 minutes was mainly cohesive failure of the composite resins, but that before UV irradiation and after 24 hours' irradiation was mainly adhesive failure. These results thus suggested that a short period of UV irradiation on composite resin teeth would improve the bonding efficacy of composite resin artificial teeth to autopolymerizing resin.

  20. Effects of gamma irradiation on the mechanical and thermal properties of cyanate ester/benzoxazine resin

    Science.gov (United States)

    Zegaoui, Abdeldjalil; Wang, An-ran; Qadeer Dayo, Abdul; Tian, Bo; Liu, Wen-bin; Wang, Jun; Liu, Yu-guang

    2017-12-01

    In this study, thermosetting resin blends composed of cyanate ester (CE) and benzoxazine (BOZ) were prepared and then subjected to gamma-ray irradiation with doses up to 1000 kGy from a cobalt-60 gamma irradiator. The objective of this present study was to experimentally assess the effect of γ-ray irradiation on the mechanical behaviour, chemical structure and thermal properties of the CE/BOZ resin blends by the bending test, dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) and thermogravimetric analysis (TGA). The results showed that at a low radiation dose (250 kGy), the flexural strength and modulus, thermal stability, storage modulus and glass transition temperature of the CE/BOZ resin gradually declined first, then sharply increased when the radiation dose increased to 500 kGy and finally slightly dropped at the end with a dose of 1000 kGy. The decrease in the aforementioned properties could be ascribed to the degradation process including the rupture of chemical bonds and scission of molecular chains of the CE/BOZ resin blends, which were confirmed by the FTIR and SEM. However, a significant improvement in the thermal and mechanical properties of the blend was found when the radiation dose increased to 500 kGy.

  1. Hydrolysis and oxidation of an epoxy resin in sub- and supercritical water

    International Nuclear Information System (INIS)

    Fromonteil, C.; Bardelle, P.; Cansell, F.

    2000-01-01

    Hydrolysis and oxidation in sub- and supercritical water has been widely studied as methods to convert organic wastes into carbon dioxide and water. This technique could be applied to destroy epoxy resin, a polymer easily used in nuclear plants. This paper deals with the behavior of an epoxy resin tested in a batch reactor. The organic network is hydrolyzed and oxidized. The influence of temperature, pressure, and residence time is studied. Low-molecular-degradation compounds are characterized by the GC/MS technique. The epoxy resin is completely destroyed by way of oxidation at 410 C and 24 MPa. The development of civil nuclear energy implies the existence of a significant number of experimental irradiations from a nuclear reactor. The main characterization of these irradiated materials relies on the study of embedded samples by a light microscope, with a coating made of epoxy resin. These materials are considered as radioactive wastes, and so their treatment is expensive and needs to reduce their volume

  2. Effect of resin coating on dentin bonding of resin cement in Class II cavities.

    Science.gov (United States)

    Sultana, Shamim; Nikaido, Toru; Matin, Khairul; Ogata, Miwako; Foxton, Richard M; Tagami, Junji

    2007-07-01

    This study was designed to evaluate the efficacy of resin coating on the regional microtensile bond strength (MTBS) of a resin cement to the dentin walls of Class II cavities. Twenty mesio-occlusal cavities were prepared in human molars. In 10 cavities, a resin coating consisting of a self-etching primer bonding system, Clearfil SE Bond, and a low-viscosity microfilled resin, Protect Liner F, was applied. The other 10 teeth served as a non-coating group. After impression taking and temporization, they were kept in water for one day. Composite inlays were then cemented with a dual-cure resin cement, Panavia F 2.0, and stored in water for one day. Thereafter, MTBSs were measured. Two-way ANOVA (p=0.05) revealed that the MTBS of resin cement to dentin was influenced by resin coating, but not by regional difference. In conclusion, application of a resin coating to the dentin surface significantly improved the MTBS in indirect restorations.

  3. Bond strength of resin-resin interfaces contaminated with saliva and submitted to different surface treatments

    Directory of Open Access Journals (Sweden)

    Adilson Yoshio Furuse

    2007-12-01

    Full Text Available The purpose of this study was to investigate the effect of different surface treatments on shear bond strength of saliva-contaminated resin-resin interfaces. Flat resin surfaces were fabricated. In the control group, no contamination or surface treatment was performed. The resin surfaces of the experimental groups were contaminated with saliva and air-dried, and then submitted to: (G1 rinsing with water and drying; (G2 application of an adhesive system; (G3 rinsing and drying, abrasion with finishing disks, etching and application of adhesive system; (G4 rinsing and drying, etching, application of silane and adhesive system. Resin cylinders were placed over the treated surfaces. The specimens were stored in water or ethanol. Shear bond strength tests were performed and the mode of failure was evaluated. Data were submitted to two-way ANOVA and Dunnett T3 test. Contamination of resin-resin interfaces with saliva significantly reduced shear strength, especially after prolonged storage (p<0.05. Similar values to the original bond strength were obtained after abrasion and application of adhesive (G3 or etching and application of silane and adhesive (G4. If contamination occurs, a surface treatment is required to guarantee an adequate interaction between the resin increments.

  4. Maximizing the functional lifetime of Protein A resins.

    Science.gov (United States)

    Zhang, Jennifer; Siva, Sethu; Caple, Ryan; Ghose, Sanchayita; Gronke, Rob

    2017-05-01

    Protein A chromatography is currently the industry gold-standard for monoclonal antibody and Fc-fusion protein purification. The high cost of Protein A, however, makes resin lifetime and resin reuse an important factor for process economics. Typical resin lifetime studies performed in the industry usually examine the effect of resin re-use on binding capacity, yield, and product quality without answering the fundamental question of what is causing the decrease in performance. A two part mechanistic study was conducted in an attempt to decouple the effect of the two possible factors (resin hydrolysis and/or degradation vs. resin fouling) on column performance over lifetime of the most commonly used alkali-stable Protein A resins (MabSelect SuRe and MabSelect SuRe LX). The change in binding capacity as a function of sodium hydroxide concentration (rate of hydrolysis), temperature, and stabilizing additives was examined. Additionally, resin extraction studies and product cycling studies were conducted to determine cleaning effectiveness (resin fouling) of various cleaning strategies. Sodium hydroxide-based cleaning solutions were shown to be more effective at preventing resin fouling. Conversely, cold temperature and the use of stabilizing additives in conjunction with sodium hydroxide were found to be beneficial in minimizing the rate of Protein A ligand hydrolysis. An effective and robust cleaning strategy is presented here to maximize resin lifetime and thereby the number of column cycles for future manufacturing processes. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:708-715, 2017. © 2017 American Institute of Chemical Engineers.

  5. Color of bulk-fill composite resin restorative materials.

    Science.gov (United States)

    Barutcigil, Çağatay; Barutcigil, Kubilay; Özarslan, Mehmet Mustafa; Dündar, Ayşe; Yilmaz, Burak

    2017-09-28

    To evaluate the color stability of novel bulk-fill composite resins. Color measurements of a nanohybrid composite resin (Z550) and 3 bulk-fill composite resins (BLK, AFX, XTF; n = 45) were performed before polymerization. After polymerization, color measurements were repeated and specimens were immersed in distilled water or red wine, or coffee. Color change [CIEDE2000 (ΔE 00 )] was calculated after 24 h, 1 and 3 weeks. Data were analyzed with Kruskal-Wallis, Mann-Whitney U and Wilcoxon tests (α = 0.05). Color changes observed after polymerization were significant for all groups. Color changes observed in distilled water for Z550 and AFX were significant. Color changes after stored in red wine and coffee were significant for all groups. Bulk-fill composite resin color change increased over time for all groups in red wine and coffee (P composite resin and bulk-fill composite resins. AFX had the highest color change in distilled water. The color of tested bulk-fill composite resins significantly changed after immersion in beverages and over time. Color change observed with the nanohybrid composite resin after 1 week was stable. Clinicians should keep in mind that tested composite resins may change color when exposed to water and significantly change color immediately after they are polymerized. In addition, the color change continues over time should the patient is a coffee and/or red wine consumer. © 2017 Wiley Periodicals, Inc.

  6. Reduction of polyester resin shrinkage by means of epoxy resin

    International Nuclear Information System (INIS)

    Pietrzak, M.; Brzostowski, A.

    1981-01-01

    An attempt was made to decrease the shrinkage of unsaturated polyester resin, taking place during radiation-induced curing, by the addition of epoxy resin. In order to combine chemically both resins, the epoxy component was modified with cinnamic and acrylic acids. A composition of 90 parts of polyester resin, 10 parts of epoxy resin modified with cinnamic acid, and 150 parts of a silica filler showed a volume shrinkage of 1.2%. (author)

  7. Volumetric polymerization shrinkage of contemporary composite resins

    Directory of Open Access Journals (Sweden)

    Halim Nagem Filho

    2007-10-01

    Full Text Available The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (a or = 0.05 was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01 and Definite (1.89±0.01 shrank significantly less than the other composite resins. SureFil (2.01±0.06, Filtek Z250 (1.99±0.03, and Fill Magic (2.02±0.02 presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

  8. Insights on the Biodegradation of Acrylic Reline Resins

    Science.gov (United States)

    Neves, Maria Cristina Bettencourt

    Acrylic reline resins are extensively used in dentistry, since they readapt dentures to the continuous reabsorbed underlying tissues. Since present in the oral cavity for long periods of time, these materials are objective of the biodegradation phenomena, which represents the change on their chemical, physical and mechanical properties due to the oral environment conditions and its constituents. These processes may permanently alter the properties of the material and compromise its function. In addition, they can promote leachable products, which in turn may induce a series of biological responses on cells and tissues. The biodegradation impact on the biocompatibility of acrylic materials is controversial but concern about its clinical significance is a fact as subjective and objective complaints about these materials are increasing. Acetylcholinesterase (AChE) has been reported to degrade methacrylatebased monomers and had a strong catalytic activity when tested in human saliva. Hence, it was the aim of chapter two of the current work to determine the effect of the enzyme AChE on the degradation of three acrylic reline resins, Probase Cold, Kooliner and Ufi Gel Hard, which contain the monomers methylmethacrylate (MMA), isobutylmethacrylate (IBMA) and 1,6-hexanodioldimethacrylate (HDMA), respectively, through the quantification of residual monomer and one common by-product methacrylic acid (MA) by High- Performance Liquid Chromatography (HPLC). These monomers were first incubated with AChE and their respective hydrolysis was monitored. The study of the degradation of the resins was done by incubating specimens of each material in 5 mL of buffer or 5 mL of buffer with AChE at 5 U/mL (pH 7.4, 37º C) for 72 h. To simulate the short-term and a long-term usage of the resins in the oral cavity, two endpoints were established: immediate exposure and late exposure. Immediate exposure was studied in eluates of specimens incubated immediately after polymerization. Late

  9. Resin composite repair: Quantitative microleakage evaluation of resin-resin and resin-tooth interfaces with different surface treatments

    OpenAIRE

    Celik, Cigdem; Cehreli, Sevi Burcak; Arhun, Neslihan

    2015-01-01

    Objective: The aim was to evaluate the effect of different adhesive systems and surface treatments on the integrity of resin-resin and resin-tooth interfaces after partial removal of preexisting resin composites using quantitative image analysis for microleakage testing protocol. Materials and Methods: A total of 80 human molar teeth were restored with either of the resin composites (Filtek Z250/GrandioSO) occlusally. The teeth were thermocycled (1000?). Mesial and distal 1/3 parts of the res...

  10. Anion-exchange resin-based desulfurization process. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sheth, A C; Dharmapurikar, R; Strevel, S D

    1994-01-01

    The following investigations were performed: (1) batch mode screening of eleven(11) commercially available resins and selection of three candidate resins for further evaluation in a fixed-bed setup. (2) Process variables study using three candidate resins in the fixed-bed setup and selection of the ``best`` resin for process economics development. (3) Exhaustion efficiency and solution concentration were found to be inversely related necessitating a trade-off between the resin cost versus the cost of evaporation/concentration of ensuing effluents. (4) Higher concentration of the HCO{sub 3}{sup {minus}} form of active sites over less active CO{sub 3}{sup 2{minus}} form of sites in the resin was believed to be the main reason for the observed increase in the equilibrium capacity of the resin at an elevated static CO{sub 2}-pressure. This Increase in capacity was found to level off around 80--120 psig range. The increase in CO{sub 2}-pressure, however, did not appear to affect the overall ion-exchange kinetics. (5) In the fixed-bed mode, the solution concentration was found to affect the equilibrium capacity of candidate resins. Their relationship was well satisfied by the Langmuir type non-linear equilibrium isotherm. Alternatively, the effect of solution concentration on overall ion-exchange kinetics varied from resin to resin. (6) Product inhibition effect on the resin was observed as an initial increase followed by a significant decrease in the resin`s equilibrium capacity for SO{sub 4}{sup 2{minus}} as the HCO{sub 3}{sup {minus}}/SO{sub 4}{sup 2{minus}} molar ratio in the solution was increased from 0 to 1.0. This ratio, however, did not affect the overall ion-exchange kinetics.

  11. Color stability, water sorption and cytotoxicity of thermoplastic acrylic resin for non metal clasp denture.

    Science.gov (United States)

    Jang, Dae-Eun; Lee, Ji-Young; Jang, Hyun-Seon; Lee, Jang-Jae; Son, Mee-Kyoung

    2015-08-01

    The aim of this study was to compare the color stability, water sorption and cytotoxicity of thermoplastic acrylic resin for the non-metal clasp dentures to those of thermoplastic polyamide and conventional heat-polymerized denture base resins. Three types of denture base resin, which are conventional heat-polymerized acrylic resin (Paladent 20), thermoplastic polyamide resin (Bio Tone), thermoplastic acrylic resin (Acrytone) were used as materials for this study. One hundred five specimens were fabricated. For the color stability test, specimens were immersed in the coffee and green tee for 1 and 8 weeks. Color change was measured by spectrometer. Water sorption was tested after 1 and 8 weeks immersion in the water. For the test of cytotoxicity, cell viability assay was measured and cell attachment was analyzed by FE-SEM. All types of denture base resin showed color changes after 1 and 8 weeks immersion. However, there was no significant difference between denture base resins. All specimens showed significant color changes in the coffee than green tee. In water sorption test, thermoplastic acrylic resin showed lower values than conventional heat-polymerized acrylic resin and thermoplastic polyamide resin. Three types of denture base showed low cytotoxicity in cell viability assay. Thermoplastic acrylic resin showed the similar cell attachment but more stable attachment than conventional heat-polymerized acrylic resin. Thermoplastic acrylic resin for the non-metal clasp denture showed acceptable color stability, water sorption and cytotoxicity. To verify the long stability in the mouth, additional in vitro studies are needed.

  12. A mechanistic study of Protein A chromatography resin lifetime.

    Science.gov (United States)

    Jiang, Canping; Liu, Jing; Rubacha, Michael; Shukla, Abhinav A

    2009-07-31

    A mechanistic study into Protein A chromatographic resin lifetime limitations is presented. Binding and mass transport properties of two widely used agarose-based Protein A resins were studied to distinguish between the roles of resin fouling due to product/impurity build-up and ligand degradation as contributory factors towards the decline in binding capacity with use. Cycling studies were conducted with and without product loading on the columns to separate out the influence of resin fouling. Ligand degradation under the mildly alkaline conditions used for column regeneration was determined to be the primary cause for Protein A resin capacity decline with usage. The use of lower concentrations of caustic and the use of stabilizing excipients to protect the Protein A ligand during cleaning and sanitization were found to be useful techniques in maintaining column performance. The results presented in this paper provide a clearer understanding of the causative factors that limit Protein A chromatographic resin lifetime. It is anticipated that these findings will assist in the development of more robust and economical downstream manufacturing processes for monoclonal antibody and Fc fusion protein purification.

  13. Biodegradation of acrylic based resins: A review.

    Science.gov (United States)

    Bettencourt, Ana F; Neves, Cristina B; de Almeida, Marise S; Pinheiro, Lídia M; Oliveira, Sofia Arantes e; Lopes, Luís P; Castro, Matilde F

    2010-05-01

    The development of different types of materials with application in dentistry is an area of intense growth and research, due to its importance in oral health. Among the different materials there are the acrylic based resins that have been extensively used either in restorations or in dentures. The objective of this manuscript was to review the acrylic based resins biodegradation phenomena. Specific attention was given to the causes and consequences of materials degradation under the oral environment. Information from scientific full papers, reviews or abstracts published from 1963 to date were included in the review. Published material was searched in dental literature using general and specialist databases, like the PubMED database. Published studies regarding the description of biodegradation mechanisms, in vitro and in vivo release experiments and cell based studies conducted on acrylic based resins or their components were evaluated. Studies related to the effect of biodegradation on the physical and mechanical properties of the materials were also analyzed. Different factors such as saliva characteristics, chewing or thermal and chemical dietary changes may be responsible for the biodegradation of acrylic based resins. Release of potential toxic compounds from the material and change on their physical and mechanical properties are the major consequences of biodegradation. Increasing concern arises from potential toxic effects of biodegradation products under clinical application thus justifying an intensive research in this area. 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. Cross-reactivity among epoxy acrylates and bisphenol F epoxy resins in patients with bisphenol A epoxy resin sensitivity.

    Science.gov (United States)

    Lee, Han N; Pokorny, Christopher D; Law, Sandra; Pratt, Melanie; Sasseville, Denis; Storrs, Frances J

    2002-09-01

    The study's objective was 2-fold: first, to evaluate the potential cross-reactivity between Bis-A epoxy resins and epoxy acrylates and second, to study the cross reactivity between Bis-A epoxy resins and newer Bis-F epoxy resins in patients with allergic contact dermatitis to epoxy resins and had positive patch test to the standard epoxy resin based on bisphenol A. Forty-one patients were patch tested to 23 chemicals including epoxy acrylates, Bis-A epoxy resins, and Bis-F epoxy resins, as well as reactive diluents and nonbisphenol epoxy resins. Questions concerning exposure to epoxy resins, occupational history, and problems with dental work were completed. All patients included in the study had positive reactions to the standard Bis-A epoxy resin. Twenty percent (8 of 41) of the patients reacted to at least one of the epoxy acrylates; the most common reaction was to Bis-GMA. Five of 8 patients who reacted to the epoxy acrylates had dental work, but only one patient had problems from her dental work. Six of 8 patients (75%) who reacted to epoxy resins and epoxy acrylates did not react to aliphatic acrylates. Thirty-two percent (13 of 41) reacted to tosylamide epoxy resin, and none reacted to triglycidyl isocyanurate resin. In addition, all patients (100%) had positive reactions to at least one of the Bis-F epoxy resins that were tested. Most patients with sensitivity to Bis-A epoxy resins do not cross-react with epoxy acrylates. Patients with positive patch test reactions to epoxy acrylates used in dentistry usually do not have symptoms from their dental work. To our knowledge, this is the largest series of patients with sensitivity to the standard Bis-A epoxy resin that have been patch tested with the more recently introduced Bis-F epoxy resins. There is significant cross-reactivity between Bis-A and Bis-F epoxy resins, which can be explained by their structural similarity. Copyright 2002, Elsevier Science (USA). All rights reserved.

  15. Aerospace Composite Materials Delivery Order 0003: Nanocomposite Polymeric Resin Enhancements for Improved Composite Performance

    National Research Council Canada - National Science Library

    Chen, Chenggang

    2002-01-01

    .... The addition of clays does not significantly alter the viscosity or cure kinetics so that the modified resin will still be suitable for liquid composite molding techniques such as resin transfer molding...

  16. Genetic Evidence for the Physiological Significance of the d-Tagatose 6-Phosphate Pathway of Lactose and d-Galactose Degradation in Staphylococcus aureus1

    Science.gov (United States)

    Bissett, Donald L.; Anderson, Richard L.

    1974-01-01

    Mutants of Staphylococcus aureus were isolated which were unable to utilize d-galactose or lactose, but which were able to utilize all other carbohydrates tested. Growth of the mutants on a peptone-containing medium was inhibited by d-galactose. Of those mutants selected for further study, one (tagI2) was missing d-galactose 6-phosphate isomerase, one (tagK3) was missing d-tagatose 6-phosphate kinase, and one (tagA4) was missing d-tagatose 1, 6-diphosphate aldolase. Each of these mutants accumulated the substrate of the missing enzyme intracellularly. Spontaneous revertants of each of the mutants simultaneously regained their ability to utilize d-galactose and lactose, lost their sensitivity to d-galactose, regained the missing enzymatic activities, and no longer accumulated intermediates of the d-tagatose 6-phosphate pathway. These data support our previous contention that the physiologically significant route for the metabolism of d-galactose and the d-galactosyl moiety of lactose in S. aureus is the d-tagatose 6-phosphate pathway. Furthermore, a mutant constitutive for all three enzymes of this pathway was isolated, indicating that the products of the tagI, tagK, and tagA genes are under common genetic control. This conclusion was supported by the demonstration that d-galactose 6-phosphate isomerase, d-tagatose 6-phosphate kinase, and d-tagatose 1, 6-diphosphate aldolase are coordinately induced in the parental strain. PMID:4277494

  17. Comparative study of resin sealant and resin modified glass ionomer as pit and fissure sealant

    Directory of Open Access Journals (Sweden)

    Shirin Malek

    2017-02-01

    Full Text Available The purpose of the present study was to compare the marginal integrity of resin modified glass ionomer cement with that of resin sealant, in vitro. Forty artificial pit and fissure cavities were prepared in occlusal surface of extracted premolar teeth by using ¼ round carbide bur. Cavities were condensed with artificial organic debris followed by cleaning with prophylaxis pumice brush and paste and then separated into two treatment groups. In Group A, 15 fissure cavities were sealed by resin sealant and in Group B, 15 fissure cavities were sealed by resin modified glass ionomer sealant. These specimens were subjected to thermo-cycling followed by dye penetration test. The remaining 5 cavities from each group were analyzed for debris score by the SEM. The results of the microleakage test showed that the efficacy of preventing microleakage of samples sealed by resin modified glass ionomer sealant was higher than the samples sealed by resin sealant. However, no significant differences were found. It can be concluded that use of resin modified glass ionomer sealant is a good alternative for sealing pits and fissures.

  18. Influence of the temperature on the dielectric properties of epoxy resins

    OpenAIRE

    Dodd, S. J.; Chalashkanov, N. M.; Fothergill, J.; Dissado, L. A.

    2010-01-01

    Electrical degradation processes in epoxy resins, such as electrical treeing, were found to be dependent on the temperature at which the experiments were carried out. Therefore, it is of considerable research interest to study the influence of temperature on the dielectric properties of the polymers and to relate the effect of temperature on these properties to the possible electrical degradation mechanisms. In this work, the dielectric properties of two different epoxy resin systems have bee...

  19. Mechanisms of Interactions of Energetic Electrons with Epoxy Resins

    Science.gov (United States)

    Gupta, A.; Coulter, D. R.; Tsay, F. D.; Moacanin, J.

    1982-01-01

    The mechanism of deactivation of energy of excitation in a resin system was investigated on optical excitation as well as excitation by high energy electrons. This mechanism involves formation of excited state complexes, known as exciplexes which have a considerable charge transfer character. This mechanism will be used to develop a degradation model for epoxy matrix materials deployed in a space environment.

  20. Effect of Resin Extract from Commiphora swynnertonii

    African Journals Online (AJOL)

    Dr Olaleye

    of Commiphora swynnertonii resin on biochemical parameters in rats was investigated. Sixty rats were ... significantly elevated protein and albumin levels but had no significant effect on bilirubin and all the liver enzymes in the rats. These findings are ... hypoglycemic and hypolipidemic effects against high fat diet- induced ...

  1. Ethylene glycol dimethacrylate cross-linking anion exchange resin as phosphate binder: effects on rat gut and digestion by small intestine contents.

    Science.gov (United States)

    Inoue, H

    2001-06-01

    In the present study, ethylene glycol dimethacrylate cross-linking 4-vinylpyridinium anion exchange resin (EGDMA-4VP) effectively bound dietary phosphate in normal rats. However, EGDMA-4VP induced more adverse effects in rat gut than cellulose or Dowex 1X2 (both of which have higher water content), and caused damage to the intestine. In order to resolve this seeming paradox, digestion of EGDMA-4VP with rat small intestine content (S-9 fraction) and carboxyl esterase was investigated in vitro to examine the stability of the resin under conditions it would be subjected to as an orally administered medicine. EGDMA-4VP was digested by small intestinal enzymes, with the exception of carboxyl esterase, and the degradation product ethylene glycol (EG) caused reversible relaxation of longitudinal muscle (but not circular muscle) in rat small intestine. Degradation products increased uptake of 3H2O into primary cultured rat small intestinal muscle cells, but the increase was not significant.

  2. PEM fuel cell degradation

    Energy Technology Data Exchange (ETDEWEB)

    Borup, Rodney L [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory

    2010-01-01

    The durability of PEM fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. While significant progress has been made in understanding degradation mechanisms and improving materials, further improvements in durability are required to meet commercialization targets. Catalyst and electrode durability remains a primary degradation mode, with much work reported on understanding how the catalyst and electrode structure degrades. Accelerated Stress Tests (ASTs) are used to rapidly evaluate component degradation, however the results are sometimes easy, and other times difficult to correlate. Tests that were developed to accelerate degradation of single components are shown to also affect other component's degradation modes. Non-ideal examples of this include ASTs examining catalyst degradation performances losses due to catalyst degradation do not always well correlate with catalyst surface area and also lead to losses in mass transport.

  3. Method for removing contaminants from plastic resin

    Science.gov (United States)

    Bohnert, George W [Harrisonville, MO; Hand, Thomas E [Lee's Summit, MO; DeLaurentiis, Gary M [Jamestown, CA

    2008-12-09

    A resin recycling method that produces essentially contaminant-free synthetic resin material in an environmentally safe and economical manner. The method includes receiving the resin in container form. The containers are then ground into resin particles. The particles are exposed to a solvent, the solvent contacting the resin particles and substantially removing contaminants on the resin particles. After separating the particles and the resin, a solvent removing agent is used to remove any residual solvent remaining on the resin particles after separation.

  4. Influence of acrylamide monomer addition to the acrylic denture-base resins on mechanical and physical properties.

    Science.gov (United States)

    Aydogan Ayaz, Elif; Durkan, Rukiye

    2013-12-01

    The aim of the study was to evaluate the effect of adding acrylamide monomer (AAm) on the characterization, flexural strength, flexural modulus and thermal degradation temperature of poly(methyl methacrylate) (PMMA) denture-base resins. Specimens (n=10) were fabricated from a conventional heat-activated QC-20 (Qc-) and a microwave heat-activated Acron MC (Ac-) PMMA resins. Powder/liquid ratio followed the manufacturer's instructions for the control groups (Qc-c and Ac-c) and for the copolymer groups, the resins were prepared with 5% (-5), 10% (-10), 15% (-15) and 20% (-20) acrylamide contents, according to the molecular weight ratio, respectively. The flexural strength and flexural modulus were measured by a three-point bending test. The data obtained were statistically analyzed by Kruskal-Wallis test (α=0.05) to determine significant differences between the groups. The chemical structures of the resins were characterized by the nuclear magnetic resonance spectroscopy. Thermal stabilities were determined by thermogravimetric analysis (TGA) with a heating rate of 10 °C⋅min(-1) from 35 °C to 600 °C. Control groups from both acrylic resins showed the lowest flexural strength values. Qc-15 showed significant increase in the flexural strength when compared to Qc-c (P<0.01). Ac-10 and Ac-15 showed significance when compared to Ac-c (P<0.01). Acrylamide incorporation increased the elastic modulus in Qc-10, Qc-15 and Qc-20 when compared to Qc-c (P<0.01). Also significant increase was observed in Ac-10, Ac-15 and Ac-20 copolymer groups when compared to Ac-c (P<0.01). According to the (1)H-nuclear magnetic resonance (NMR) results, acrylamide copolymerization was confirmed in the experimental groups. TGA results showed that the thermal stability of PMMA is increased by the insertion of AAm.

  5. Studies of transformation and particle-binding of resin acids during oxidative treatment of effluent from two New Zealand pulp mills.

    Science.gov (United States)

    Kanber, S A; Langdon, A G; Wilkins, A L

    2008-02-01

    Reactor studies of aerobic degradation of effluent from the first and last ponds of the treatment system of two New Zealand pulp and paper mills indicated that filterable BOD(5), resin acids and transformed resin acids, free and bound, degraded at similar rates. During oxidative treatment the resin acids of untreated effluent became increasingly bound to particulate material and a sediment high in abiet-13-enoic acid was formed.

  6. Effect of accelerated aging on the microhardness and color stability of flexible resins for dentures

    Directory of Open Access Journals (Sweden)

    Marcelo Coelho Goiato

    2010-03-01

    Full Text Available Acrylic resins have been widely used due to their acceptable esthetics and desirable characteristics such as easy handling, good thermal conductivity, low permeability to oral fluids and color stability. Flexible resins were introduced on the market as an alternative to the use of conventional acrylic resins in the construction of complete and partial removable dentures. Although these resins present advantages in terms of esthetics and comfort, studies assessing chromatic and microhardness alterations of these materials are still scarce in the related literature. The aim of this study was to evaluate the chromatic and microhardness alterations of two commercial brands of flexible resins in comparison to the conventional resin Triplex when submitted to accelerated aging. The resins were manipulated according to manufacturers' instructions and inserted into a silicone matrix to obtain 21 specimens divided into 3 groups: Triplex, Ppflex and Valplast. Triplex presented the highest microhardness value (p < 0.05 for all the aging periods, which was significantly different from that of the other resins, followed by the values of Valplast and Ppflex. Comparison between the flexible resins (Ppflex and Valplast revealed a statistically significant difference (p < 0.05 as regards color. The flexible resin Ppflex and the conventional resin Triplex presented no statistically significant difference (p < 0.05 as regards aging. The accelerated aging significantly increased the microhardness values of the resins, with the highest values being observed for Triplex. Valplast presented the greatest chromatic alteration after accelerated aging.

  7. Contact allergy to epoxy resin

    DEFF Research Database (Denmark)

    Bangsgaard, Nannie; Thyssen, Jacob Pontoppidan; Menné, Torkil

    2012-01-01

    to epoxy resin remained stable over the study period. Of the patients with an epoxy resin-positive patch test, 71% returned a questionnaire; 95 patients had worked with epoxy resin in the occupational setting, and, of these, one-third did not use protective gloves and only 50.5% (48) had participated...

  8. Processing of exhausted resins for Trino NPP,

    International Nuclear Information System (INIS)

    Benvenuto, F.; Bitetti, G.; Maggini, F.; Scarsi, G.

    2009-01-01

    Decomposition of organic compounds contained in the spent ion exchange resins is considered effective in reducing the waste volume. A system using the wet-oxidation process has been studied for the treatment of the spent resins stored at Trino Nuclear Power Plant owned by SOGIN. Compared with various processes for treating sludge and resin, the wet-oxidation system is rather simple and the process conditions are mild. Not contaminated ion exchange resin samples similar to those ones used in Trino NPP were processed by wet-oxidation and appropriate decomposition of the organic compounds was verified. After decomposition the residue can be solidified with cement for final disposal. When compared with direct solidification without decomposition, the number of waste packages can be significantly reduced. Additional measures for conditioning secondary waste products have also been studied, and their applicability to the Trino Nuclear Power Plant was verified. Some of conditions studied were specific to the Trino Nuclear Power Plant, but it is expected that the system will provide an effective solution for resin treatment at other Italian NPPs. (authors)

  9. Enhancement of adhesion between resin coating materials and resin cements.

    Science.gov (United States)

    Udo, Tomoaki; Nikaido, Toru; Ikeda, Masaomi; Weerasinghe, Dinesh S; Harada, Naoko; Foxton, Richard M; Tagami, Junji

    2007-07-01

    Resin coating technique is a unique method that improves the dentin bond strength of resin cements in indirect restorations. However, the weak link of a specimen bonded using the resin coating technique was reported to be the bonded interface between the resin coating material and resin cement. The purpose of this study, therefore, was to enhance the bonding performance between a resin coating material and a resin cement. Two light-cured flowable composites, Protect Liner F and Clearfil Flow FX, were used as coating materials, and two dual-cure composite materials, Panavia F 2.0 and Clearfil DC Core Automix, were used as resin cements. The ultimate tensile strength of each material and the microtensile bond strengths of the bonded specimens of resin coating material and resin cement were measured using a crosshead speed of 1.0 mm/min. Three-way ANOVA (p=0.05) revealed that the highest microtensile bond strength was obtained using a combination of Clearfil Flow FX and Clearfil DC Core Automix, and when the surface of the coating material was treated with ED Primer II. It was strongly suggested that materials with a higher ultimate tensile strength, when used in both resin coating and cementation, could enhance the bond strength between the two.

  10. Resin impregnation process for producing a resin-fiber composite

    Science.gov (United States)

    Palmer, Raymond J. (Inventor); Moore, William E. (Inventor)

    1994-01-01

    Process for vacuum impregnation of a dry fiber reinforcement with a curable resin to produce a resin-fiber composite, by drawing a vacuum to permit flow of curable liquid resin into and through a fiber reinforcement to impregnate same and curing the resin-impregnated fiber reinforcement at a sufficient temperature and pressure to effect final curing. Both vacuum and positive pressure, e.g. autoclave pressure, are applied to the dry fiber reinforcement prior to application of heat and prior to any resin flow to compact the dry fiber reinforcement, and produce a resin-fiber composite of reduced weight, thickness and resin content, and improved mechanical properties. Preferably both a vacuum and positive pressure, e.g. autoclave pressure, are also applied during final curing.

  11. Resin injection in clays with high plasticity

    Science.gov (United States)

    Nowamooz, Hossein

    2016-11-01

    Regarding the injection process of polyurethane resins in clays with high plasticity, this paper presents the experimental results of the pressuremeter and cone penetration tests before and after injection. A very important increase in pressure limit or in soil resistance can be observed for all the studied depths close to the injection points. An analytical analysis for cylindrical pore cavity expansion in cohesive frictional soils obeying the Mohr-Coulomb criterion was then used to reproduce the pressuremeter tests before and after injection. The model parameters were calibrated by maintaining constant the elasticity parameters as well as the friction angel before and after injection. A significant increase in cohesion was observed because of soil densification after resin expansion. The estimated undrained cohesions, derived from the parameters of the Mohr-Coulomb criterion, were also compared with the cone penetration tests. Globally, the model predictions show the efficiency of resin injection in clay soils with high plasticity.

  12. Effect of various teas on color stability of resin composites.

    Science.gov (United States)

    Dinç Ata, Gül; Gokay, Osman; Müjdeci, Arzu; Kivrak, Tugba Congara; Mokhtari Tavana, Armin

    2017-12-01

    To investigate the effect of various teas on color stability of resin composites. Two methacrylate-based (Arabesk Top, Grandio) and a silorane-based (Filtek Silorane) resin composites were used. 110 cylindrical samples of each resin composite were prepared (2 mm thickness and 8 mm diameter), polished and stored in distilled water (37°C for 24 hours). They were randomly divided into 11 groups (n= 10) and color measurements were taken. Then the samples were immersed in tap water (control), a black tea, a green tea or one of the eight herbal-fruit teas (37°C for 1 week) and subsequently subjected to the final color measurements. The color change of samples (ΔE*) was calculated, data were subjected to two-way ANOVA and Tukey's HSD tests. Teas, resin composites and their interactions were significant (P= 0.000). All the teas and control caused color changes in all three resin composites. Rosehip tea caused the most color changes, while tap water showed the least in all resin composites. Arabesk Top had the most staining potential in all the teas and control, whereas Filtek Silorane was the most stain resistant except Grandio immersed in sage tea. Color stability of all resin composites used were affected from both structure of resin materials and constituents of teas used. All resin composites were susceptible to staining by all teas especially rosehip tea. Arabesk Top composite showed the greatest color susceptibility in all teas and Filtek Silorane the least with one exception. Color of resin composites can be negatively affected from teas consumed. Clinicians should advise patients that drinking different kind of teas could intensify surface staining of resin based restorations.

  13. PILOT-SCALE HYDRAULIC TESTING OF RESORCINOL FORMALDEHYDE ION EXCHANGE RESIN

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, D

    2007-01-09

    morphology. The skeletal density of the RF resin in the 24-inch IX Column increased slightly with cycling (in both hydrogen and sodium form). The chemical solutions used in the pilot-scale testing remained clear throughout testing, indicating very little chemical breakdown of the RF resin beads. The RF resin particles did not break down and produce fines, which would have resulted in higher pressure drops across the resin bed. Three cesium (Cs) loading tests were conducted on the RF resin in pilot-scale IX columns. Laboratory analyses concluded the Cs in the effluent never exceeded the detection limit. Therefore, there was no measurable degradation in cesium removal performance. Using the pilot-scale systems to add the RF resin to the columns and removing the resin from the columns was found to work well. The resin was added and removed from the columns three times with no operational concerns. Whether the resin was in sodium or hydrogen form, the resin flowed well and resulted in an ideal resin bed formation during each Resin Addition. During Resin Removal, 99+ % of the resin was easily sluiced out of the IX column. The hydraulic performance of the spherical RF resin during cycle testing was found to be superior to all other tested IX resins, and SRNL testing indicates that the resin should hold up to many cycles in actual radioactive Cs separation. The RF resin was found to be durable in the long term cycle testing and should result in a cost saving in actual operations when compared to other IX resins.

  14. PILOT-SCALE HYDRAULIC TESTING OF RESORCINOL FORMALDEHYDE ION EXCHANGE RESIN

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, D

    2006-11-08

    morphology. The skeletal density of the RF resin in the 24 inch IX Column increased slightly with cycling (in both hydrogen and sodium form). The chemical solutions used in the pilot-scale testing remained clear throughout testing, indicating very little chemical breakdown of the RF resin beads. The RF resin particles did not break down and produce fines, which would have resulted in higher pressure drops across the resin bed. Three cesium (Cs) loading tests were conducted on the RF resin in pilot-scale IX columns. Laboratory analyses concluded the Cs in the effluent never exceeded the detection limit. Therefore, there was no measurable degradation in cesium removal performance. Using the pilot-scale systems to add the RF resin to the columns and removing the resin from the columns was found to work well. The resin was added and removed from the columns three times with no operational concerns. Whether the resin was in sodium or hydrogen form, the resin flowed well and resulted in an ideal resin bed formation during each Resin Addition. During Resin Removal, 99+ % of the resin was easily sluiced out of the IX column. The hydraulic performance of the spherical RF resin during cycle testing was found to be superior to all other tested IX resins, and SRNL testing indicates that the resin should hold up to many cycles in actual radioactive Cs separation. The RF resin was found to be durable in the long term cycle testing and should result in a cost saving in actual operations when compared to other IX resins.

  15. PILOT-SCALE HYDRAULIC TESTING OF RESORCINOL FORMALDEHYDE ION EXCHANGE RESIN

    International Nuclear Information System (INIS)

    Adamson, D

    2007-01-01

    morphology. The skeletal density of the RF resin in the 24-inch IX Column increased slightly with cycling (in both hydrogen and sodium form). The chemical solutions used in the pilot-scale testing remained clear throughout testing, indicating very little chemical breakdown of the RF resin beads. The RF resin particles did not break down and produce fines, which would have resulted in higher pressure drops across the resin bed. Three cesium (Cs) loading tests were conducted on the RF resin in pilot-scale IX columns. Laboratory analyses concluded the Cs in the effluent never exceeded the detection limit. Therefore, there was no measurable degradation in cesium removal performance. Using the pilot-scale systems to add the RF resin to the columns and removing the resin from the columns was found to work well. The resin was added and removed from the columns three times with no operational concerns. Whether the resin was in sodium or hydrogen form, the resin flowed well and resulted in an ideal resin bed formation during each Resin Addition. During Resin Removal, 99+ % of the resin was easily sluiced out of the IX column. The hydraulic performance of the spherical RF resin during cycle testing was found to be superior to all other tested IX resins, and SRNL testing indicates that the resin should hold up to many cycles in actual radioactive Cs separation. The RF resin was found to be durable in the long term cycle testing and should result in a cost saving in actual operations when compared to other IX resins

  16. Comparison of Mechanical Properties of Resin Composites with Resin Modified Glass Ionomers

    Directory of Open Access Journals (Sweden)

    Taha NA

    2015-06-01

    Full Text Available Statement of Problem: There are controversial reports regarding physical and mechanical properties of resin composites and glass ionomer cements. Some revealed higher strength and hardness for resin composites while others showed a comparable value for glass ionomer cements. Evaluation of mechanical properties of different types of resin composites in comparison with resin modified glass ionomers is not widely studied. Objectives: To measure and compare the flexural strength and Vickers hardness of three resin composites and two resins modified glass ionomer cements before and after ageing. Materials and Methods: Three resin composites, i.e. Filtek Supreme XTE (3M ESPE, Ice (SDI, Gradia (GC, and two resins modified glass ionomers, i.e. Fuji II LC (GC and Riva Light Cure (SDI, were selected. Ten barshaped specimens were prepared for each material and cured using LED curing light. After 24 hours storage in distilled water at 37oC, the specimens were randomly divided into two equal groups (n=5. The first group was tested as a baseline and the second group was restored at 37oC for another 29 days. Flexural strength was performed by four-point bending test using universal testing machine at crosshead speed of 0.5mm/min, and the maximum load at failure was recorded. The specimen’s halves were used for evaluating Vickers hardness, using a Digital Hardness Tester (300 g/15 sec and the Vickers hardness number (VHN was recorded. Data were analyzed using one-way analysis of variance (ANOVA, Tukey’s and student’s t-test. Results: After 24 hours of immersion, the highest hardness number was found for Filtek Supreme and Ice and the highest flexural strength was obtained for Gradia. After 30 days of storage, hardness of Fuji II LC and Gradia showed a significant decrease; flexural strength of Ice and Fuji II LC revealed a significant increase while Gradia and Filtek Supreme showed a significant decrease. Conclusions: Resin modified glass ionomers showed

  17. Electron-beam curing of epoxy resins

    Indian Academy of Sciences (India)

    Electron-beam (e-beam) induced polymerization of epoxy resins proceeds via cationic mechanism in presence of suitable photoinitiator. Despite good thermal properties and significant processing advantages, epoxy-based composites manufactured using e-beam curing suffer from low compressive strength, poor ...

  18. Comparison of stabilities in translucency, fluorescence and opalescence of direct and indirect composite resins.

    Science.gov (United States)

    Yu, Bin; Lee, Young-Keun

    2013-01-01

    To evaluate translucency, fluorescence and opalescence stabilities of direct and indirect composite resins after aging. One direct (16 shades) and two indirect composite resins (16 and 26 shades) were investigated. Resins were filled in a mold (1 mm thick) and light cured; post-curings were performed for indirect resins. Color was measured before and after 5,000 cycles of thermocycling on a reflection spectrophotometer in reflectance and transmittance modes to calculate parameters for translucency (TP), fluorescence (FL) and opalescence (OP). Differences in the changes of TP, FL and OP after aging by the type of resin were determined by t test, and those were also determined by one-way ANOVA with the factor of the brand or the shade group (P resins; and were -2.0 to 1.8, -0.9 to 0.4 and -2.9 to 3.7, respectively, for indirect resins. Changes in TP were not significantly different by the type of resin, but those in FL and OP were different (P = 0.05). Changes in optical parameters were influenced by the brand or the shade group of the resins (P resins varied depending on type, brand or shade group. Aging significantly affected fluorescence and opalescence, but not translucency, of indirect resins compared to those of direct resins.

  19. Attribute based selection of thermoplastic resin for vacuum infusion process

    DEFF Research Database (Denmark)

    Prabhakaran, R.T. Durai; Lystrup, Aage; Løgstrup Andersen, Tom

    2011-01-01

    The composite industry looks toward a new material system (resins) based on thermoplastic polymers for the vacuum infusion process, similar to the infusion process using thermosetting polymers. A large number of thermoplastics are available in the market with a variety of properties suitable...... for different engineering applications, and few of those are available in a not yet polymerised form suitable for resin infusion. The proper selection of a new resin system among these thermoplastic polymers is a concern for manufactures in the current scenario and a special mathematical tool would...... be beneficial. In this paper, the authors introduce a new decision making tool for resin selection based on significant attributes. This article provides a broad overview of suitable thermoplastic material systems for vacuum infusion process available in today’s market. An illustrative example—resin selection...

  20. Evaluation of matrices for immobilizing ion-exchange resins

    International Nuclear Information System (INIS)

    Buckley, L.P.; Speranzini, R.A.

    1980-07-01

    Ion exchange resins make up a significant fraction of the volume of radioactive wastes generated during the operation of CANDU-PHW nuclear power stations. Since permanent disposal will eventually be required for these contaminated ion-exchange resins, some way to reduce their volume and to immobilize their radionuclides is required. An evaluation of the processes for immobilizing contaminated ion exchange resins directly into glasses, plastics, bitumens and cements is reported here. Releases of Cs-137, Co-60 and C-14 in leach testss were found to be lowest for bitumen followed by glasses, plastics and cements. Approximately 8% of the C-14 inventory on the ion-exchange resins is released into the off-gas system during glass formation and could limit use of this option. A pyrolysis method for a three-fold reduction in the volume of used ion-exchange resins is described. (auth)

  1. Effect of photoactivation on the reduction of composite resin contamination.

    Science.gov (United States)

    Pauletti, Natalia A; Girotto, Luiza P S; Leite, Françoise H S; Mario, Débora N

    2017-06-01

    Composite resins are predominantly marketed in developing countries in tube form, and the contents of the tube may be used in numerous procedures for different patients. This represents a problem because of the risk of cross-contamination. This study aimed to evaluate contamination in vitro of the internal contents of composite resin tubes in the dental clinics of a higher-education institution, as well as the effect of photoactivation on the level of contamination. Twenty-five tubes containing composite resin were randomly chosen (by lottery). From each tube, two samples of approximately 2 mm of composite resin were removed, and then one sample, but not the other, was photoactivated. These samples were plated on Brain-Heart Infusion (BHI), Sabouraud and MacConkey agars, and the plates were incubated at 37°C for 24-48 h. Colony counting and Gram staining were performed for subsequent microscopic identification of fungi and bacteria. The non-photoactivated composite resin group presented significantly higher microbial contamination in relation to the photoactivated composite resin group. The photoactivation of camphorquinone present in composite resin produces reactive oxygen species, which might promote cell death of contaminant microorganisms. Thus, although the same tube of composite resin may be used for a number of different patients in the dental clinics of developing countries, the photoactivation process potentially reduces the risk of cross-contamination. © 2017 Eur J Oral Sci.

  2. Relined fiberglass post: an ex vivo study of the resin cement thickness and dentin-resin interface

    Directory of Open Access Journals (Sweden)

    Niélli Caetano de SOUZA

    Full Text Available Abstract The aim of this study was to evaluate the thickness of resin cements in the root thirds when using conventional fiberglass posts (CP and relined fiberglass posts (RP in weakened roots and to evaluate the morphological characteristics of the dentin-resin interface. Forty human maxillary anterior teeth had the crown sectioned below the cemento-enamel junction. The canals were endodontically treated and weakened with diamond burs. Teeth were divided into four groups (n = 10: Group 1 – CP + RelyX ARC; Group 2 – CP + RelyX U200; Group 3 – RP + RelyX ARC; and Group 4 – RP + RelyX U200. Prior to luting, 0.1% Fluorescein and 0.1% Rhodamine B dyes were added to an adhesive and resin cement, respectively. Slices were obtained from the apical, middle, and cervical thirds of the root. Confocal laser scanning microscopy images were recorded in four areas (buccal, lingual, mesial, distal of each third. In each area, four equidistant measures of the resin cement were made and the mean value was calculated. The interface morphology was observed. The data were submitted to three-way ANOVA and Tukey’s test (α = 0.05. The interaction between fiberglass posts, resin cement, and root thirds was significant (p < 0.0001. The resin cement thicknesses were significantly lower for RP in comparison with CP, except in the apical third. There was no significant difference between the resin cements for RP. There was formation of resin cement tags and adhesive tags along the root for RP. RP favored the formation of thin and uniform resin cement films and resin tags in weakened roots.

  3. Relined fiberglass post: an ex vivo study of the resin cement thickness and dentin-resin interface.

    Science.gov (United States)

    Souza, Niélli Caetano de; Marcondes, Maurem Leitão; Breda, Ricardo Vaz; Weber, João Batista Blessmann; Mota, Eduardo Gonçalves; Spohr, Ana Maria

    2016-08-18

    The aim of this study was to evaluate the thickness of resin cements in the root thirds when using conventional fiberglass posts (CP) and relined fiberglass posts (RP) in weakened roots and to evaluate the morphological characteristics of the dentin-resin interface. Forty human maxillary anterior teeth had the crown sectioned below the cemento-enamel junction. The canals were endodontically treated and weakened with diamond burs. Teeth were divided into four groups (n = 10): Group 1 - CP + RelyX ARC; Group 2 - CP + RelyX U200; Group 3 - RP + RelyX ARC; and Group 4 - RP + RelyX U200. Prior to luting, 0.1% Fluorescein and 0.1% Rhodamine B dyes were added to an adhesive and resin cement, respectively. Slices were obtained from the apical, middle, and cervical thirds of the root. Confocal laser scanning microscopy images were recorded in four areas (buccal, lingual, mesial, distal) of each third. In each area, four equidistant measures of the resin cement were made and the mean value was calculated. The interface morphology was observed. The data were submitted to three-way ANOVA and Tukey's test (α = 0.05). The interaction between fiberglass posts, resin cement, and root thirds was significant (p < 0.0001). The resin cement thicknesses were significantly lower for RP in comparison with CP, except in the apical third. There was no significant difference between the resin cements for RP. There was formation of resin cement tags and adhesive tags along the root for RP. RP favored the formation of thin and uniform resin cement films and resin tags in weakened roots.

  4. Effects of abrasive and fiber components in medium on wear of composite resins.

    Science.gov (United States)

    Kakuta, Kiyoshi; Ogura, Hideo

    2008-09-01

    Effects of abrasive and fiber components in a medium on the wear behavior of composite resins were evaluated. Calcium diphosphate and methyl cellulose were included in the medium as abrasive and fiber components respectively. A range of 0, 4, or 8% abrasive- or fiber-containing media were applied on a composite resin specimen during a simulated occlusal wear test. Four composite resins, Clearfil AP-X, Z100 Restorative, SOLARE P, and SOLIDEX F, were tested to evaluate the effects of these components in the medium. Presence of abrasive material in the medium increased the wear of composite resins significantly, but its effect differed among the composite resins. Presence of fiber material in the medium significantly decreased the wear of two composite resins, whereas the other two composites showed no significant differences. Nonetheless, presence of fiber in the medium generally tended to prevent the wear of composite resins.

  5. Effect of configuration factor on gap formation in hybrid composite resin, low-shrinkage composite resin and resin-modified glass ionomer.

    Science.gov (United States)

    Boroujeni, Parvin M; Mousavinasab, Sayyed M; Hasanli, Elham

    2015-05-01

    Polymerization shrinkage is one of the important factors in creation of gap between dental structure and composite resin restorations. The aim of this study was to evaluate the effect of configuration factor (C-factor) on gap formation in a hybrid composite resin, a low shrinkage composite resin and a resin modified glass ionomer restorative material. Cylindrical dentin cavities with 5.0 mm diameter and three different depths (1.0, 2.0 and 3.0 mm) were prepared on the occlusal surface of 99 human molars and the cavities assigned into three groups (each of 33). Each group contained three subgroups depend on the different depths and then cavities restored using resin modified glass ionomer (Fuji II LC Improved) and two type composite resins (Filtek P90 and Filtek Z250). Then the restorations were cut into two sections in a mesiodistal direction in the middle of restorations. Gaps were measured on mesial, distal and pulpal floor of the cavities, using a stereomicroscope. Data analyses using Kruskal-Wallist and Mann-Whitney tests. Increasing C-factor from 1.8 to 3.4 had no effect on the gap formation in two type composite resins, but Fuji II LC Improved showed significant effect of increasing C-factor on gap formation. Taken together, when C-factor increased from 1.8 up to 3.4 had no significant effect on gap formation in two tested resin composites. Although, Filtek P90 restorations showed smaller gap formation in cavities walls compared to Filtek Z250 restorations. High C-factor values generated the largest gap formation. Silorane-based composite was more efficient for cavity sealing than methacrylate-based composites and resin modified glass ionomer. © 2014 Wiley Publishing Asia Pty Ltd.

  6. Waste minimization pretreatment via pyrolysis and oxidative pyrolysis of organic ion exchange resin

    International Nuclear Information System (INIS)

    Chun, U.K.; Choi, K.; Yang, K.H.; Park, J.K.; Song, M.J.

    1998-01-01

    Pyrolysis and/or oxidative pyrolysis of organic ion exchange resins and other combustible waste may be effective pretreatment processes before vitrification. Three different methods were examined with the TGA to pretreat the resins: pyrolysis; oxidative pyrolysis; and oxidative pyrolyses of ash remaining after the pyrolysis of resin. The latter two methods were found to provide better volume reduction than the pyrolysis-only process. Between the two types of resins, cationic and anionic, the cationic exchange resin was less volatile. Pyrolysis and oxidative pyrolysis of mixed resin (50% cation and 50% anion by wt.) showed volatilization at the temperatures where volatilization was observed for each of the separate resins. Because of certain limitations of the commercial TGA, tube furnace experiments were performed, generally, to examine the pyrolysis of larger quantities of cationic, anionic, and mixed resin, and to examine off-gas characteristics. The cationic resin-only and anionic resin-only gravimetric results showed good agreement with the smaller-scale TGA results. SEM pictures of the different variants of the resin (cationic, anionic, and mixed) show a different morphology for each. Off-gas data showed the presence of H 2 S, SO 2 , CO, and NO during the pyrolysis of cationic resin. CO was observed during the pyrolysis of anionic resin. The mixed resin trials showed the presence of the gases approximately at the temperatures where the gases would evolve if the results of the two different resins (cationic and anionic) were superimposed. However, the amount of hydrogen sulfide relative to the sulfur dioxide was found to increase significantly compared to the results of the cationic resin-only trials

  7. INFLUENCE OF ENVIRONMENTAL CONDITIONS ON PROPERTIES OF IONOMERIC AND RESIN SEALANT MATERIALS

    Science.gov (United States)

    Kantovitz, Kamila Rosamilia; Pascon, Fernanda Miori; Correr, Gisele Maria; Alonso, Roberta Caroline Bruschi; Rodrigues, Lidiany Karla Azevedo; Alves, Marcelo Correa; Puppin-Rontani, Regina Maria

    2009-01-01

    Objectives: The aim of this study was to determine the effect of environmental conditions on the degradation of ionomeric and resin sealant materials. Material and Methods: FluroShield, Vitremer, and Ketac Molar disc-shaped specimens (n=18/material) were prepared, polished, subjected to initial hardness and roughness readings. Six discs of each material were randomly assigned to one of three different storage solutions: 0.3% citric acid (CA), demineralization solution (DE), and remineralization solution (RE). The specimens were individually immersed in 3 mL of the test solutions, which were daily changed. After 15 days of storage, new surface roughness and hardness readings were done. Fluoride release in the solutions was measured within 15 days. Data were analyzed by ANOVA and Tukey's and Contrast tests (α=0.05). Results: The storage in CA increased the roughness of Vitremer and Ketac Molar. A significant reduction in hardness was observed for all materials after storage in all solutions. For all materials, the greatest amounts of fluoride release occurred during the 1st day. FluroShield presented the same patterns of fluoride release in all solutions. Ketac Molar and Vitremer released the highest amounts of fluoride in the CA solution. Conclusions: Ionomeric materials are more susceptible to degradation than resin-based materials under acidic conditions. Acidic conditions lead to a higher fluoride release from ionomeric materials. PMID:19668988

  8. Flame Retardant Epoxy Resins

    Science.gov (United States)

    Thompson, C. M.; Smith, J. G., Jr.; Connell, J. W.; Hergenrother, P. M.; Lyon, R. E.

    2004-01-01

    As part of a program to develop fire resistant exterior composite structures for future subsonic commercial aircraft, flame retardant epoxy resins are under investigation. Epoxies and their curing agents (aromatic diamines) containing phosphorus were synthesized and used to prepare epoxy formulations. Phosphorus was incorporated within the backbone of the epoxy resin and not used as an additive. The resulting cured epoxies were characterized by thermogravimetric analysis, propane torch test, elemental analysis and microscale combustion calorimetry. Several formulations showed excellent flame retardation with phosphorous contents as low as 1.5% by weight. The fracture toughness of plaques of several cured formulations was determined on single-edge notched bend specimens. The chemistry and properties of these new epoxy formulations are discussed.

  9. Bond strength of composite resin to enamel: assessment of two ethanol wet-bonding techniques.

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2014-04-01

    Full Text Available Ethanol wet-bonding (EWB technique has been stated to decrease degradation of resin-dentin bond. This study evaluated the effect of two EWB techniques on composite resin-to-enamel bond strength.Silicon carbide papers were used to produce flat enamel surfaces on the buccal faces of forty-five molars. OptiBond FL (OFL adhesive was applied on enamel surfaces in three groups of 15 namely: Enamel surface and OFL (control;Protocol 1 of the EWB technique: absolute ethanol was applied to water-saturated acid-etched enamel surfaces for 1 minute before the application of ethanol-solvated hydrophobic adhesive resin of OFL 3 times;Protocol 2: progressive ethanol replacement; water was gradually removed from the enamel matrix using ascending ethanol concentrations before OFL application. Composite build-ups were made and the specimens were stored for 24 hours at 37°C and 100% relative humidity. Shear bond strength test was performed using a universal testing machine at 1 mm/min crosshead speed. Fracture patterns were evaluated microscopically. Data were analyzed with one-way ANOVA and Fisher's exact test (α=0.05.There were no significant differences in bond strength between the groups (P=0.73. However, regarding failure patterns, the highest cohesive enamel fractures were recorded in groups 2 and 3.In this study, although both methods of EWB did not influence immediate bond strength of composite resin to enamel, the majority of failure patterns occurred cohesively in enamel.

  10. Experimental study and model development for 'uranium dioxide-epoxy resin' heat treatment

    International Nuclear Information System (INIS)

    Chairat, Aziza

    2015-01-01

    In order to characterize nuclear fuels, samples are currently embedded in an epoxy polymer resin. In storage conditions, the presence of organic products in contact with highly radioactive material generates gas due to a radiolysis phenomenon. Samples management imposes the definition of a fuel and resin separation process. This work aims at developing a tool for the optimal design and control of a suitable heat treatment process. This development is based on experiments and on the modeling of the resin pyrolysis reactions coupled to mass, heat and momentum transfers. One of the difficulties of the study lies to the needed process control on various scales: i) on a global scale to represent the treatment conditions and ii) on a local scale to represent the conditions close to fuel material. This study uses a combined modeling - simulation approach with experiments carried out with the help of a thermo-balance for kinetic data acquisition, on the one hand and in an experimental oven, on the other hand. The process will be performed in two stages, resin pyrolysis and residue (Char) oxidation. Nuclear fuel can be oxidized during both stages. Indeed, the pyrolysis degrades the resin and generated pyrolysis gases, which produce an oxidizing atmosphere. Oxidation of pyrolysis residue can modify the structure of spent fuel and liberate fission gases. The resin pyrolysis produced non-condensable gases, steam, tar and char. The final hydrogen content in the char has to be as low as possible and close to zero to be sure that the radiolysis phenomenon will never occur during of nuclear fuel storage. The process development has been carried out in stages. The first step is to investigate the overall kinetics of epoxy degradation and the determination of the generated gas kinetics. The influence of the presence of nuclear fuel is investigated with epoxy-UO 2 mixture. The results showed no significant effect of the nuclear fuel presence. The second part is the coupling of

  11. Bismaleimide Copolymer Matrix Resins

    Science.gov (United States)

    Parker, John A.; Heimbuch, Alvin H.; Hsu, Ming-Ta S.; Chen, Timothy S.

    1987-01-01

    Graphite composites, prepared from 1:1 copolymer of two new bismaleimides based on N,N'-m-phenylene-bis(m-amino-benzamide) structure have mechanical properties superior to those prepared from other bismaleimide-type resins. New heat-resistant composites replace metal in some structural applications. Monomers used to form copolymers with superior mechanical properties prepared by reaction of MMAB with maleic or citraconic anhydride.

  12. System for removing contaminants from plastic resin

    Science.gov (United States)

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2010-11-23

    A resin recycling system that produces essentially contaminant-free synthetic resin material in an environmentally safe and economical manner. The system includes receiving the resin in container form. A grinder grinds the containers into resin particles. The particles are exposed to a solvent in one or more solvent wash vessels, the solvent contacting the resin particles and substantially removing contaminants on the resin particles. A separator is used to separate the resin particles and the solvent. The resin particles are then placed in solvent removing element where they are exposed to a solvent removing agent which removes any residual solvent remaining on the resin particles after separation.

  13. Paramagnetic epoxy resin

    Directory of Open Access Journals (Sweden)

    E. C. Vazquez Barreiro

    2017-01-01

    Full Text Available This work illustrates that macrocycles can be used as crosslinking agents for curing epoxy resins, provided that they have appropriate organic functionalities. As macrocycles can complex metal ions in their structure, this curing reaction allows for the introduction of that metal ion into the resin network. As a result, some characteristic physical properties of the metallomacrocycle could be transferred to the new material. The bisphenol A diglycidyl ether (BADGE, n = 0 and hemin (a protoporphyrin IX containing the Fe(III ion, and an additional chloride ligand have been chosen. The new material has been characterized by differential scanning calorimetry (DSC, thermogravimetric analysis (TGA, Fourier Transform Infrared (FT-IR, Nuclear Magnetic Resonance (NMR, Transmission Electron Microscopy (TEM, and magnetic susceptibility measurements. Fe(III remains in the high-spin state during the curing process and, consequently, the final material exhibits the magnetic characteristics of hemin. The loss of the chlorine atom ligand during the cure of the resin allows that Fe(III can act as Lewis acid, catalyzing the crosslinking reactions. At high BADGE n = 0/hemin ratios, the formation of ether and ester bonds occurs simultaneously during the process.

  14. Influence of Bovine Dentin Site on the Bond Strength of Resin Cement

    OpenAIRE

    Tohru, HAYAKAWA; Hiroyuki, MISHIMA; Shuichi, YAMAKAWA; Mikiko, MASUDA; Masahiro, AIDA; Kimiya, NEMOTO; Yukishige, KOZAWA; Department of Dental Materials, Research Institute of Oral Science, Nihon Univerity School of Dentistry at Matsudo; Department of Anatomy, Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo; Department of Crown and Bridge Prosthodontics, Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo; Department of Crown and Bridge Prosthodontics, Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo; Department of Crown and Bridge Prosthodontics, Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo; Department of Dental Materials, Research Institute of Oral Science, Nihon Univerity School of Dentistry at Matsudo; Department of Anatomy, Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo

    2001-01-01

    The purpose of this study is to investigate the influences of types of resin cements and dentin site(crown and root part)on the adhesion of resin cement to dentin. Three types of resin cements; Super-Bond C&B, Bistite II and Scotchbond Resin Cement were used. The tensile bond strength of each resin cement to crown and root dentin of bovine incisors was measured after 24 hours immersion in water at 37℃. Super-Bond C&B showed no significant difference in bond strength between crown and root den...

  15. Synthesis and Characterization of Bio-Oil Phenol Formaldehyde Resin Used to Fabricate Phenolic Based Materials.

    Science.gov (United States)

    Cui, Yong; Hou, Xiaopeng; Wang, Wenliang; Chang, Jianmin

    2017-06-18

    In this study, bio-oil from the fast pyrolysis of renewable biomass was used as the raw material to synthesize bio-oil phenol formaldehyde (BPF) resin-a desirable resin for fabricating phenolic-based material. During the synthesis process, paraformaldehyde was used to achieve the requirement of high solid content and low viscosity. The properties of BPF resins were tested. Results indicated that BPF resin with the bio-oil addition of 20% had good performance on oxygen index and bending strength, indicating that adding bio-oil could modify the fire resistance and brittleness of PF resin. The thermal curing behavior and heat resistance of BPF resins were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Results showed that adding bio-oil had an impact on curing characteristics and thermal degradation process of PF resin, but the influence was insignificant when the addition was relatively low. The chemical structure and surface characteristics of BPF resins were determined by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The analysis demonstrated that adding bio-oil in the amount of 20% was able to improve the crosslinking degree and form more hydrocarbon chains in PF resin.

  16. Effect of surface treatment on the bonding of an autopolymerizing soft denture liner to a denture base resin.

    Science.gov (United States)

    Minami, Hiroyuki; Suzuki, Shiro; Ohashi, Hirohumi; Kurashige, Hisanori; Tanaka, Takuo

    2004-01-01

    This in vitro study evaluated the effects of surface treatments and thermocycling on the bonding of autopolymerizing silicone soft denture liner (Sofreliner) to denture base resin. The bonding surfaces of denture base cylinders were polished with 600-grit silicon carbide paper and pretreated with applications of Sofreliner Primer, Sofreliner Primer after air abrasion, Reline Primer, or Reline Primer after air abrasion. Failure loads and elongation at failure were measured after subjecting specimens to 0, 10,000, 20,000, and 30,000 thermocycles. Failure modes were assessed for all specimens. Seven specimens were fabricated for each of 16 groups, including four pretreatments and four thermocycle groups. Failure loads of the Sofreliner Primer group were significantly higher than those of the air-abrasion group up to 20,000 thermocycles; both groups showed cohesive failures of the soft denture liner. Failure loads of the Reline Primer group were significantly higher than with Reline Primer after air abrasion up to 10,000 thermocycles. Failure mode after 10,000 thermocycles was cohesive for the Reline Primer group and mixed cohesive/adhesive for Reline Primer after air abrasion. Failure loads of the Sofreliner Primer group were significantly higher than those of the Reline Primer group at each thermocycling interval. Elongation values decreased after 10,000 thermocycles for all groups. Air abrasion on the denture base resin surface was not effective in enhancing failure load. Cyclic thermal stress is one factor degrading the bond between soft denture liner and acrylic resin denture base.

  17. Biokompatibilitas Gelas Ionomer Modifikasi Resin

    OpenAIRE

    Rotua Lestari M

    2008-01-01

    Saat ini banyak berkembang material baru dalam dunia kedokteran gigi diantaranya adalah Gelas ionomer modifikasi resin yang dikembangkan untuk mengatasi kekurangan-kekurangan dari gelas ionomer konvensional. Adanya penambahan monomer resin daIam bentuk 2-hydroxyethylmetacylate (HEMA) telah meningkatkan kekuatan dari bahan ini. Gelas ionomer modifikasi resin mempunyai sifat-sifat fisis dan mekanis yang lebih baik dibandingkan dengan gelas ionomer konvensional. Gelas ionomer modifikasi ...

  18. Properties of injection-molded thermoplastic polyester denture base resins.

    Science.gov (United States)

    Hamanaka, Ippei; Takahashi, Yutaka; Shimizu, Hiroshi

    2014-02-01

    This study investigated the properties of injection-molded thermoplastic polyester denture base resins. Two injection-molded thermoplastic polyester denture base resins (polyethylene terephthalate copolymer and polycycloalkylene terephthalate copolymer) were tested. Specimens of each denture base material were fabricated for flexural properties testing, Charpy impact testing and shear bond testing (n = 10). The flexural strength at the proportional limit, elastic modulus, Charpy impact strength and the shear bond strength of the two denture base materials were estimated. The polycycloalkylene terephthalate copolymer denture base resin had significantly lower flexural strength at the proportional limit, lower elastic modulus, higher impact strength and lower shear bond strength compared to the polyethylene terephthalate copolymer denture base resin. The properties of the injection-molded thermoplastic denture base resins composed of polyethylene terephthalate copolymer and polycycloalkylene terephthalate copolymer were different from each other. The polycycloalkylene terephthalate copolymer denture base resin had significantly lower flexural strength at the proportional limit, lower elastic modulus, higher impact strength and lower shear bond strength compared to the polyethylene terephthalate copolymer denture base resin.

  19. Investigation of degradation products produced by recycling the solvent during chemical degradation of fiber-reinforced composites

    DEFF Research Database (Denmark)

    Ucar, Hülya; Simonsen, Morten Enggrob; Søgaard, Erik Gydesen

    2017-01-01

    of solvent consumption by 88%. It was found that the recycled solvent became increasingly more concentrated with degradation products from the epoxy resin and compounds produced by acetone aldol reactions. These degradation products promoted and enhanced the degradation of the composite. Among the compounds...... produced by acetone aldol reaction, the industrially important bulk chemical mesityl oxide accounted for 68–79% of the total chromatographic peak area. Simultaneously, with the optimization of a process for converting composite waste into its constituent (fibers and resin), valuable bulk chemicals can...

  20. A study on the compatibility between one-bottle dentin adhesives and composite resins using micro-shear bond strength.

    Science.gov (United States)

    Song, Minju; Shin, Yooseok; Park, Jeong-Won; Roh, Byoung-Duck

    2015-02-01

    This study was performed to determine whether the combined use of one-bottle self-etch adhesives and composite resins from same manufacturers have better bond strengths than combinations of adhesive and resins from different manufacturers. 25 experimental micro-shear bond test groups were made from combinations of five dentin adhesives and five composite resins with extracted human molars stored in saline for 24 hr. Testing was performed using the wire-loop method and a universal testing machine. Bond strength data was statistically analyzed using two way analysis of variance (ANOVA) and Tukey's post hoc test. Two way ANOVA revealed significant differences for the factors of dentin adhesives and composite resins, and significant interaction effect (p composite resin (p composite resin than other manufacturer's composite resin. Not all combinations of adhesive and composite resin by same manufacturers failed to show significantly higher bond strengths than mixed manufacturer combinations.

  1. In Vitro Analysis of the Fracture Resistance of CAD/CAM Denture Base Resins

    Directory of Open Access Journals (Sweden)

    Otto Steinmassl

    2018-03-01

    Full Text Available Computer-aided design and computer-aided manufacturing (CAD/CAM denture base manufacturers claim to produce their resin pucks under high heat and pressure. Therefore, CAD/CAM dentures are assumed to have enhanced mechanical properties and, as a result, are often produced with lower denture base thicknesses than conventional, manually fabricated dentures. The aim of this study was to investigate if commercially available CAD/CAM denture base resins have more favourable mechanical properties than conventionally processed denture base resins. For this purpose, a series of three-point bending tests conforming to ISO specifications were performed on a total of 80 standardised, rectangular CAD/CAM denture base resin specimens from five different manufacturers (AvaDent, Baltic Denture System, Vita VIONIC, Whole You Nexteeth, and Wieland Digital Dentures. A heat-polymerising resin and an autopolymerising resin served as the control groups. The breaking load, fracture toughness, and the elastic modulus were assessed. Additionally, the fracture surface roughness and texture were investigated. Only one CAD/CAM resin showed a significantly increased breaking load. Two CAD/CAM resins had a significantly higher fracture toughness than the control groups, and all CAD/CAM resins had higher elastic moduli than the controls. Our results indicate that CAD/CAM denture base resins do not generally have better mechanical properties than manually processed resins. Therefore, the lower minimum denture base thicknesses should be regarded with some caution.

  2. In Vitro Analysis of the Fracture Resistance of CAD/CAM Denture Base Resins.

    Science.gov (United States)

    Steinmassl, Otto; Offermanns, Vincent; Stöckl, Wolfgang; Dumfahrt, Herbert; Grunert, Ingrid; Steinmassl, Patricia-Anca

    2018-03-08

    Computer-aided design and computer-aided manufacturing (CAD/CAM) denture base manufacturers claim to produce their resin pucks under high heat and pressure. Therefore, CAD/CAM dentures are assumed to have enhanced mechanical properties and, as a result, are often produced with lower denture base thicknesses than conventional, manually fabricated dentures. The aim of this study was to investigate if commercially available CAD/CAM denture base resins have more favourable mechanical properties than conventionally processed denture base resins. For this purpose, a series of three-point bending tests conforming to ISO specifications were performed on a total of 80 standardised, rectangular CAD/CAM denture base resin specimens from five different manufacturers (AvaDent, Baltic Denture System, Vita VIONIC, Whole You Nexteeth, and Wieland Digital Dentures). A heat-polymerising resin and an autopolymerising resin served as the control groups. The breaking load, fracture toughness, and the elastic modulus were assessed. Additionally, the fracture surface roughness and texture were investigated. Only one CAD/CAM resin showed a significantly increased breaking load. Two CAD/CAM resins had a significantly higher fracture toughness than the control groups, and all CAD/CAM resins had higher elastic moduli than the controls. Our results indicate that CAD/CAM denture base resins do not generally have better mechanical properties than manually processed resins. Therefore, the lower minimum denture base thicknesses should be regarded with some caution.

  3. Interactions between resin monomers and commercial composite resins with human saliva derived esterases.

    Science.gov (United States)

    Jaffer, F; Finer, Y; Santerre, J P

    2002-04-01

    Cholesterol esterase (CE) and pseudocholinesterase (PCE) have been reported to degrade commercial and model composite resins containing bisphenylglycidyl dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA) or the latter in combination with urethane modified BisGMA monomer systems. In addition, human saliva has been shown to contain esterase like activities similar to CE and PCE. Hence, it was the aim of the current study to determine to what extent human saliva could degrade two common commercial composite resins (Z250 from 3M Inc. and Spectrum TPH from L.D. Caulk) which contain the above monomer systems. Saliva samples from different volunteers were collected, processed, pooled, and freeze-dried. TEGDMA and BisGMA monomers were incubated with human saliva derived esterase activity (HSDEA) and their respective hydrolysis was monitored using high performance liquid chromatography (HPLC). Both monomers were completely hydrolyzed within 25 h by HSDEA. Photopolymerized composites were incubated with buffer or human saliva (pH 7.0 and 37 C) for 2, 8 and 16 days. The incubation solutions were analyzed using HPLC and mass spectrometry. Surface morphology characterization was carried out using scanning electron microscopy. Upon biodegradation, the Z250 composite yielded higher amounts of BisGMA and TEGDMA related products relative to the TPH composite. However, there were higher amounts of ethoxylated bis-phenol A released from the TPH material. In terms of total mass of products released, human saliva demonstrated a greater ability to degrade Z250. In summary, HSDEA has been shown to contain esterase activities that can readily catalyze the biodegradation of current commercial composite resins.

  4. The effect of toothbrushing on surface gloss of resin composites.

    Science.gov (United States)

    Lefever, Dorien; Perakis, Nikolaos; Roig, Miguel; Krejci, Ivo; Ardu, Stefano

    2012-02-01

    To determine the changes in surface gloss of different composite materials after laboratory toothbrushing simulation. 36 specimens were fabricated for each material and polished with 120-, 220-, 500-, 1200-, 2400- and 4000-grit SiC abrasive paper, respectively. Gloss measurements were made with a glossmeter (Novocurve) prior to testing procedures and then subjected to simulated toothbrushing for 5, 15, 30 and 60 minutes by means of an electric toothbrush with a pressure of 2N while being immersed in a 50 RDA toothpaste slurry. Four supplementary samples per group were analyzed under SEM immediately after polishing procedures and four samples after 60 minutes simulated toothbrushing in order to evaluate the causes of the gloss decrease. The tested resin composite materials were Filtek Supreme XTE, Durafill, HRi Enamel Plus, Miris 2, Empress Direct, Venus Diamond, Gradia Direct, Clearfil Photo Posterior and G-aenial. Natural enamel represented the control group. Statistical analysis was performed using Kruskal Wallis and Tukey post-hoc test, with a level of significance set at 0.05. Resin composite initial gloss values ranged from 68.9 to 100.5 at baseline to 10.6 to 62.6 after 1 hour of brushing. Highest gloss values were obtained by Filtek Supreme XTE, followed by Empress Direct and Durafill. Lowest values were obtained by Clearfil Photoposterior, Miris 2, Enamel HRi and Venus Diamond. Natural enamel was the only substrate to maintain its gloss throughout the brushing procedure (110.4 after 60 minutes). SEM analysis revealed different patterns of surface degradation depending on the composite material.

  5. Sustainable nitrate-contaminated water treatment using multi cycle ion-exchange/bioregeneration of nitrate selective resin.

    Science.gov (United States)

    Ebrahimi, Shelir; Roberts, Deborah J

    2013-11-15

    The sustainability of ion-exchange treatment processes using high capacity single use resins to remove nitrate from contaminated drinking water can be achieved by regenerating the exhausted resin and reusing it multiple times. In this study, multi cycle loading and bioregeneration of tributylamine strong base anion (SBA) exchange resin was studied. After each cycle of exhaustion, biological regeneration of the resin was performed using a salt-tolerant, nitrate-perchlorate-reducing culture for 48 h. The resin was enclosed in a membrane to avoid direct contact of the resin with the culture. The results show that the culture was capable of regenerating the resin and allowing the resin to be used in multiple cycles. The concentrations of nitrate in the samples reached a peak in first 0.5-1h after placing the resin in medium because of desorption of nitrate from resin with desorption rate of 0.099 ± 0.003 hr(-1). After this time, since microorganisms began to degrade the nitrate in the aqueous phase, the nitrate concentration was generally non-detectable after 10h. The average of calculated specific degradation rate of nitrate was -0.015 mg NO3(-)/mg VSS h. Applying 6 cycles of resin exhaustion/regeneration shows resin can be used for 4 cycles without a loss of capacity, after 6 cycles only 6% of the capacity was lost. This is the first published research to examine the direct regeneration of a resin enclosed in a membrane, to allow reuse without any disinfection or cleaning procedures. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Automated characterization of varnishes photo-degradation using portable T-controlled Raman spectroscopy

    Science.gov (United States)

    Osticioli, I.; Ciofini, D.; Mencaglia, A. A.; Siano, S.

    2017-02-01

    In this work, a portable-Raman device (excitation wavelength 1064 nm) was employed for the first time for continuously monitoring the complex molecular dynamics of terpenoid resins (dammar, mastic, colophony, sandarac and shellac), which occur during their ageing under artificial light exposure. The instrumentation was equipped with a pyroelectric sensor allowing for temperature control of the sample's irradiated surface while the acquisition of spectra occurs by setting fixed maximum temperature and total radiant exposure. Resins were dropped into special pits over a dedicated rotating wheel moved by a USB motor. The rotation allowed samples sliding between the positions designated for the acquisition of the Raman spectra and that for artificial ageing. Samples were exposed to artificial light for 45-days and almost 400 spectra for each resin sample were collected. The exposure to artificial light led to significant changes allowing the characterization of the alteration process. The automated acquisition of a large number of spectra overtime during light-exposure has given the possibility to distinguish fast dynamics, mainly associated to solvent evaporation, from those slower due to resins photo-degradation processes.

  7. Microtensile bond strength of indirect resin composite to resin-coated dentin: interaction between diamond bur roughness and coating material.

    Science.gov (United States)

    Kameyama, Atsushi; Oishi, Takumi; Sugawara, Toyotarou; Hirai, Yoshito

    2009-02-01

    This aim of this study was to determine the effect of type of bur and resin-coating material on microtensile bond strength (microTBS) of indirect composite to dentin. Dentin surfaces were first ground with two types of diamond bur and resin-coated using UniFil Bond (UB) or Adper Single Bond (SB), and then bonded to a resin composite disc for indirect restoration with adhesive resin cement. After storage for 24 hr in distilled water at 37 degrees C, microTBS was measured (crosshead speed 1 mm/min). When UB was applied to dentin prepared using the regular-grit diamond bur, microTBS was significantly lower than that in dentin prepared using the superfine-grit bur. In contrast, no significant difference was found between regular-grit and superfine-grit bur with SB. However, more than half of the superfine-grit specimens failed before microTBS testing. These results indicate that selection of bur type is important in improving the bond strength of adhesive resin cement between indirect resin composite and resin-coated dentin.

  8. In vitro enamel remineralization capacity of composite resins containing sodium trimetaphosphate and fluoride.

    Science.gov (United States)

    Tiveron, Adelisa Rodolfo Ferreira; Delbem, Alberto Carlos Botazzo; Gaban, Gabriel; Sassaki, Kikue Takebayashi; Pedrini, Denise

    2015-11-01

    This study evaluated the in vitro enamel remineralization capacity of experimental composite resins containing sodium trimetaphosphate (TMP) combined or not with fluoride (F). Bovine enamel slabs were selected upon analysis of initial surface hardness (SH1) and after induction of artificial carious lesions (SH2). Experimental resins were as follows: resin C (control—no sodium fluoride (NaF) or TMP), resin F (with 1.6% NaF), resin TMP (with 14.1% TMP), and resin TMP/F (with NaF and TMP). Resin samples were made and attached to enamel slabs (n = 12 slabs per material). Those specimens (resin/enamel slab) were subjected to pH cycling to promote remineralization, and then final surface hardness (SH3) was measured to calculate the percentage of surface hardness recovery (%SH). The integrated recovery of subsurface hardness (ΔKHN) and F concentration in enamel were also determined. Data was analyzed by ANOVA and Student-Newman-Keuls test (p Resins F and TMP/F showed similar SH3 values (p = 0.478) and %SH (p = 0.336) and differed significantly from the other resins (p resin TMP/F presented the lowest area of lesion (p resins (p = 0.042), but higher than in the other resins (p composite resin enhanced its capacity for remineralization of enamel in vitro. The combination of two agents with action on enamel favored remineralization, suggesting that composite resins containing sodium trimetaphosphate and fluoride could be indicated for clinical procedures in situations with higher cariogenic challenges.

  9. PERFORMANCE OF MUF RESINS FOR PARTICLEBOARDS BEFORE AND AFTER SPRAY-DRYING

    Directory of Open Access Journals (Sweden)

    Antonio PIZZI

    2012-12-01

    Full Text Available Melamine-urea-formaldehyde (MUF resins can be spray dried to obtain resins in powder form and indefinite shelf-life. Application as particleboard adhesives of such resins after redissolving them in water does yield resins of excellent performance as particleboard adhesives if the natural advancement caused by the heat in the spray-drier chamber is taken into account. CP MAS 13C NMR analysis of the spray-dried resin in powder form and thermomechanical analysis has shown some difference in behaviour in relation to MUF resins of the same level of water tolerance which have not been spray-dried. These small but significant differences can be ascribed to differences in resin structure.

  10. Effect of Porcelain Surface Pretreatments on Composite Resin-Porcelain Shear Bond Strength

    Science.gov (United States)

    1991-05-01

    compared shear bond strengths between mechanically retained, silicoated, and sputter coated orthodontic brackets cemented with three different cements...between composite resin and porcelain, it is thought that thermocycling accelerates the hydrolysis induced degradation of the composite resin-porcelain bond...Bonding Orthodontic Attachments to Porcelain Teeth Using a Silane Coupling Agent, Am J Orthod 77: 233. Jones, D. W. (1985): Low Fusing Porcelains. In

  11. Mechanical properties of injection-molded thermoplastic denture base resins.

    Science.gov (United States)

    Hamanaka, Ippei; Takahashi, Yutaka; Shimizu, Hiroshi

    2011-03-01

    To investigate the mechanical properties of injection-molded thermoplastic denture base resins. Four injection-molded thermoplastic resins (two polyamides, one polyethylene terephthalate, one polycarbonate) and, as a control, a conventional heat-polymerized polymethyl methacrylate (PMMA), were used in this study. The flexural strength at the proportional limit (FS-PL), the elastic modulus, and the Charpy impact strength of the denture base resins were measured according to International Organization for Standardization (ISO) 1567 and ISO 1567:1999/Amd 1:2003. The descending order of the FS-PL was: conventional PMMA > polyethylene terephthalate, polycarbonate > two polyamides. The descending order of the elastic moduli was: conventional PMMA > polycarbonate > polyethylene terephthalate > two polyamides. The descending order of the Charpy impact strength was: polyamide (Nylon PACM12) > polycarbonate > polyamide (Nylon 12), polyethylene terephthalate > conventional PMMA. All of the injection-molded thermoplastic resins had significantly lower FS-PL, lower elastic moduli, and higher or similar impact strength compared to the conventional PMMA. The polyamide denture base resins had low FS-PL and low elastic moduli; one of them possessed very high impact strength, and the other had low impact strength. The polyethylene terephthalate denture base resin showed a moderately high FS-PL, moderate elastic modulus, and low impact strength. The polycarbonate denture base resin had a moderately high FS-PL, moderately high elastic modulus, and moderate impact strength.

  12. A comparative study to determine strength of autopolymerizing acrylic resin and autopolymerizing composite resin influenced by temperature during polymerization: An In Vitro study

    Directory of Open Access Journals (Sweden)

    Anuj Chhabra

    2017-01-01

    Full Text Available Aim: Temporary coverage of a prepared tooth is an important step during various stages of the fixed dental prosthesis. Provisional restorations should satisfy proper mechanical requirements to resist functional and nonfunctional loads. A few studies are carried out regarding the comparison of the effect of curing environment, air and water, on mechanical properties of autopolymerizing acrylic and composite resin. Hence, the aim of this study was to compare the transverse strength of autopolymerizing acrylic resin and autopolymerizing composite resin as influenced by the temperature of air and water during polymerization. Materials and Methods: Samples of autopolymerizing acrylic resin and composite resin were prepared by mixing as per manufacturer's instructions and were placed in a preformed stainless steel mold. The mold containing the material was placed under different controlled conditions of water temperature and air at room temperature. Polymerized samples were then tested for transverse strength using an Instron universal testing machine. Results: Alteration of curing condition during polymerization revealed a significant effect on the transverse strength. The transverse strength of acrylic resin specimens cured at 60°C and composite resin specimens cured at 80°C was highest. Polymerizing the resin in cold water at 10°C reduced the mechanical strength. Conclusions: Polymerization of the resin in hot water greatly increased its mechanical properties. The method of placing resin restoration in hot water during polymerization may be useful for improving the mechanical requirements and obtaining long-lasting performance.

  13. Properties of the Carboxylate ion exchange resins

    International Nuclear Information System (INIS)

    Allard, Bert; Dario, Maarten; Boren, Hans; Torstenfelt, Boerje; Puigdomenech, Ignasi; Johansson, Claes

    2002-09-01

    Weakly acidic, carboxylic resin has been selected, together with strong base anion resins, for water purification at the Forsmark 1 and 2 reactors. For the strong (but not the weak) ion exchange resin the Nuclear Power Inspectorate has given permission to dispose the spent resins in the SFR 1 (the Final Repository for Radioactive Operational Waste). This report gives a review of the carboxylic resins and comes to the conclusion that the resins are very stable and that there should not exist any risks for increased leaching of radionuclides from SFR 1 if these resins are disposed (compared to the strong resins)

  14. Differences in color, translucency and fluorescence between flowable and universal resin composites.

    Science.gov (United States)

    Yu, Bin; Lee, Yong-Keun

    2008-10-01

    To evaluate the optical properties such as color, translucency and fluorescence of flowable resin composites, and compare them with the corresponding shade universal resin composites of the same brand. Four brands of flowable and universal resin composites of the same shade designation (A2) were investigated. Color of specimens (2mm in thickness) was measured after polymerization on a reflection spectrophotometer over background of white, black and each corresponding composite material itself. Color differences (DeltaE(ab)(*)) between each combination of resin composites were determined. Translucency parameter (TP) and color difference by the fluorescent emission (DeltaE(ab)(*)-FL) of materials were also calculated. Differences in the optical properties of flowable and universal resin composites were analyzed with one-way ANOVA. DeltaE(ab)(*) between the flowable and the corresponding universal resin composites was in the range of 1.0-6.0 DeltaE(ab)(*) units, which was perceptible (DeltaE(ab)(*)>2.6) in three brands. Flowable resin composites revealed lower TP values in two of the four brands. DeltaE(ab)(*) between flowable and the corresponding universal resin composites was influenced by their difference in translucency. All the four universal resin composites and two flowable resin composites showed fluorescent peak, and the range of DeltaE(ab)(*)-FL was 0.3-2.3 DeltaE(ab)(*) units. Optical properties of flowable and universal resin composites was significantly different (presin composites should be considered for clinically acceptable color matching.

  15. Development of a High-Throughput Ion-Exchange Resin Characterization Workflow.

    Science.gov (United States)

    Liu, Chun; Dermody, Daniel; Harris, Keith; Boomgaard, Thomas; Sweeney, Jeff; Gisch, Daryl; Goltz, Bob

    2017-06-12

    A novel high-throughout (HTR) ion-exchange (IEX) resin workflow has been developed for characterizing ion exchange equilibrium of commercial and experimental IEX resins against a range of different applications where water environment differs from site to site. Because of its much higher throughput, design of experiment (DOE) methodology can be easily applied for studying the effects of multiple factors on resin performance. Two case studies will be presented to illustrate the efficacy of the combined HTR workflow and DOE method. In case study one, a series of anion exchange resins have been screened for selective removal of NO 3 - and NO 2 - in water environments consisting of multiple other anions, varied pH, and ionic strength. The response surface model (RSM) is developed to statistically correlate the resin performance with the water composition and predict the best resin candidate. In case study two, the same HTR workflow and DOE method have been applied for screening different cation exchange resins in terms of the selective removal of Mg 2+ , Ca 2+ , and Ba 2+ from high total dissolved salt (TDS) water. A master DOE model including all of the cation exchange resins is created to predict divalent cation removal by different IEX resins under specific conditions, from which the best resin candidates can be identified. The successful adoption of HTR workflow and DOE method for studying the ion exchange of IEX resins can significantly reduce the resources and time to address industry and application needs.

  16. Relationship between Color and Translucency of Multishaded Dental Composite Resins

    Directory of Open Access Journals (Sweden)

    Homan Naeimi Akbar

    2012-01-01

    Full Text Available The aim of the present study was to compare the translucency of different shades of two highly aesthetic multilayered restorative composite resins. In total nine shades from Esthet.X and ten shades from Filtek Supreme composite resins were chosen. Discs of each shade were prepared (N=3 and light-cured. Total and diffuse transmittance values for each sample were measured. Statistical analysis showed that the opaque dentine shades of both composites were the least translucent and the enamel shades had the highest translucency. There was a significant decrease in translucency from A2 to C2 of regular body shades and also from A4 to C4 of opaque dentine shades of Esthet.X composite resin. Grey enamel shade had a significantly higher diffuse translucency compared to clear and yellow enamel shades. There was a significant decrease in translucency from A2B to D2B and also in diffuse translucency from A4D to C6D shades of Filtek Supreme composite resin. It can be concluded that the color of the composite resins tested in this study had a significant effect on their translucency. Information on the translucency of different shades of composite resins can be very useful for the clinicians in achieving optimal esthetic restorative outcome.

  17. [Acrylic resin removable partial dentures

    NARCIS (Netherlands)

    Baat, C. de; Witter, D.J.; Creugers, N.H.J.

    2011-01-01

    An acrylic resin removable partial denture is distinguished from other types of removable partial dentures by an all-acrylic resin base which is, in principle, solely supported by the edentulous regions of the tooth arch and in the maxilla also by the hard palate. When compared to the other types of

  18. Cure shrinkage in casting resins

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, J. Brock [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-02-01

    A method is described whereby the shrinkage of a casting resin can be determined. Values for the shrinkage of several resin systems in frequent use by Sandia have been measured. A discussion of possible methods for determining the stresses generated by cure shrinkage and thermal contraction is also included.

  19. Effect of phytic acid etchant on resin-dentin bonding: Monomer penetration and stability of dentin collagen.

    Science.gov (United States)

    Kong, Kalyan; Hiraishi, Noriko; Nassar, Mohannad; Otsuki, Masayuki; Yiu, Cynthia K Y; Tagami, Junji

    2017-07-01

    Phytic acid (IP6) works well as an etchant in dentin bonding to remove the smear layer due to its acidity and chelating effect. This study compared the etching effect of IP6 with phosphoric acid (PA) and ethylenediaminetetraacetic acid (EDTA) on resin-dentin bond strength, micromorphology of the etched dentin surface and nanoleakage formation along resin-dentin interfaces and compared the protecting effect against collagen degradation. Dentin disks and flat dentin surfaces were obtained from extracted human teeth. Specimens were etched with 35% PA (15s), 0.5M EDTA (30s) or 1% IP6 (30s). The surfaces and longitudinal sections of the etched dentin disks were observed using field emission scanning electron microscope (FE-SEM). An etch-and-rinse adhesive was used to create composite build up-specimens for microtensile bond strength (μTBS) testing and nanoleakage observation. To evaluate the effect on collagen degradation, demineralized bovine root dentin blocks were challenged with bacterial collagenase and then observed under light microscope. PA- and EDTA- treated groups showed significantly lower μTBS when compared to IP6-treated group. PA showed distinct nanoleakage and severe collagen degradation. Only slight nanoleakage was detected in IP6 group. IP6 showed better effect than EDTA in preventing collagen degradation induced by bacterial collagenase. IP6 effectively removed the smear layer and etched dentin, providing high bond strength values and causing minimal nanoleakage and slight collagen degradation. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  20. Ceramic matrix and resin matrix composites - A comparison

    Science.gov (United States)

    Hurwitz, Frances I.

    1987-01-01

    The underlying theory of continuous fiber reinforcement of ceramic matrix and resin matrix composites, their fabrication, microstructure, physical and mechanical properties are contrasted. The growing use of organometallic polymers as precursors to ceramic matrices is discussed as a means of providing low temperature processing capability without the fiber degradation encountered with more conventional ceramic processing techniques. Examples of ceramic matrix composites derived from particulate-filled, high char yield polymers and silsesquioxane precursors are provided.

  1. Ceramic matrix and resin matrix composites: A comparison

    Science.gov (United States)

    Hurwitz, Frances I.

    1987-01-01

    The underlying theory of continuous fiber reinforcement of ceramic matrix and resin matrix composites, their fabrication, microstructure, physical and mechanical properties are contrasted. The growing use of organometallic polymers as precursors to ceramic matrices is discussed as a means of providing low temperature processing capability without the fiber degradation encountered with more conventional ceramic processing techniques. Examples of ceramic matrix composites derived from particulate-filled, high char yield polymers and silsesquioxane precursors are provided.

  2. Shear Bond Strength between Fiber-Reinforced Composite and Veneering Resin Composites with Various Adhesive Resin Systems.

    Science.gov (United States)

    AlJehani, Yousef A; Baskaradoss, Jagan K; Geevarghese, Amrita; AlShehry, Marey A; Vallittu, Pekka K

    2016-07-01

    The aim of this research was to evaluate the shear bond strength of different laboratory resin composites bonded to a fiber-reinforced composite substrate with some intermediate adhesive resins. Mounted test specimens of a bidirectional continuous fiber-reinforced substrate (StickNet) were randomly assigned to three equal groups. Three types of commercially available veneering resin composites - BelleGlass®, Sinfony®, and GC Gradia® were bonded to these specimens using four different adhesive resins. Half the specimens per group were stored for 24 hours; the remaining were stored for 30 days. There were 10 specimens in the test group (n). The shear bond strengths were calculated and expressed in MPa. Data were analyzed statistically, and variations in bond strength within each group were additionally evaluated by calculating the Weibull modulus. Shear bond values of those composites are influenced by the different bonding resins and different indirect composites. There was a significant difference in the shear bond strengths using different types of adhesive resins (p = 0.02) and using different veneering composites (p veneering composite to bidirectional continuous fiber-reinforced substrate is influenced by the brand of the adhesive resin and veneering composite. © 2015 by the American College of Prosthodontists.

  3. Dentine deproteinization and microleakage around gingival third resin restorations

    OpenAIRE

    Shetty, Sowmya; B, Mithra; B, Sureshchandra

    2008-01-01

    Objectives: A significant factor in achieving satisfactory adhesion of restorative resins to dentine substrate is the method by which the dentine surface is treated before an adhesive is applied. The aim of this study was to evaluate the effect of deproteinization on microleakage around gingival third resin restorations. Materials and Methods: Standardised Class V preparations were made on randomly selected intact upper and lower human molars. These were treated in one of five ways (no treatm...

  4. Effect of pressure on dynamic heterogeneity in dendrimeric alkyd resin

    Science.gov (United States)

    Paluch, M.; Sekula, M.; Maślanka, S.; Mańczyk, K.; Sułkowski, W. W.; Rzoska, S. J.; Ziolo, J.

    2004-01-01

    Broadband dielectric spectroscopy is employed to investigate the non-Debye relaxation behavior in a dendrimeric alkyd resin. From temperature-dependent measurements at ambient pressure, we found a very broad distribution of relaxation times. This is attributed to the complex geometrical topology of the molecule. However, compression significantly reduces the non-Debye character of the dielectric response; thus, pressure induces dynamic homogeneity in the dendrimeric alkyd resin.

  5. Selective removal of carbon-14 from ion exchange resins using supercritical carbon dioxide

    International Nuclear Information System (INIS)

    Dias, S.A.; Krasznai, J.P.

    1996-01-01

    Ion exchange resins (IX) are used extensively in CANDU-PHWR (Canada Deuterium Uranium - Pressurized Heavy Water Reactor) and other reactor systems worldwide to remove ionic contaminants from various coolant circuits. Spent IX resins represent a significant volume of low and intermediate level radioactive waste. The presence of long-lived C-14 which is found in significant quantities in IX resins from CANDU reactors, complicates the disposal of these resins. Several experiments were conducted with carbon dioxide under subcritical and supercritical conditions to determine the feasibility of removing C-14 present as carbonate and/or bicarbonate on IX resins. It has been established that resins containing inorganic C-14 undergo rapid isotopic exchange when exposed to inactive carbon dioxide under supercritical conditions. This treatment reduces the C-14 to the limits of detection and leaves other radioisotopes on the resins largely unaffected. This selective and highly efficient means to remove long-lived C-14 activity from CANDU spent IX resins allows the resin waste to be reclassified as low level waste. This lower classification simplifies the handling, transportation and eventual disposal of IX resins which translates to a very significant cost saving. Since the process is selective the C-14 can be enriched and recovered for commercial purposes

  6. Effect of sealant agents on the color stability and surface roughness of nanohybrid composite resins.

    Science.gov (United States)

    Dede, Doğu Ömür; Şahin, Onur; Koroglu, Aysegül; Yilmaz, Burak

    2016-07-01

    The effect of sealant agents on the surface roughness and color stability of nanohybrid composite resins is unknown. The purpose of this in vitro study was to evaluate the effect of sealant agents on the surface roughness and color stability of 4 nanohybrid composite resin materials. Forty disks (10×2 mm) were fabricated for each nanohybrid composite resin material (Z-550, Tetric EvoCeram, Clearfill Majesty, Ice) (N=160) and divided into 4 surface treatment groups: 1 conventional polishing (control) and 3 different sealant agent (Palaseal, Optiglaze, BisCover) coupling groups (n=10). The specimens were thermocycled, and surface roughness (Ra) values were obtained with a profilometer. Scanning electron microscope images were also recorded. CIELab color parameters of each specimen were measured with a spectrophotometer before and after 7 days of storage in a coffee solution. Color differences were calculated by the CIEDE 2000 (ΔE00) formula. The data were statistically analyzed by 2-way ANOVA and by the Tukey HSD test (α=.05). The surface treatment technique significantly affected the Ra values of the composite resins tested (Pcomposite resin material was also significant for ΔE00 values (Pcomposite resin groups, significant decreases in Ra were observed only for the Palaseal agent coupled composite resin groups (except Ice) compared with the control groups (Pcomposite resin group, except for BisCover applied Clearfill Majesty (Pcomposite resin groups, significant differences were observed between the color change seen with BisCover and other sealants for Clearfill Majesty composite resin (Pcomposite resins except for Ice produced smoother surfaces. All surface sealant agents provided less discoloration of nanohybrid composite resins after coffee staining compared with conventional polishing except for BisCover applied Clearfill Majesty composite resin. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All

  7. Nanomechanical properties of dental resin-composites.

    Science.gov (United States)

    El-Safty, S; Akhtar, R; Silikas, N; Watts, D C

    2012-12-01

    To determine by nanoindentation the hardness and elastic modulus of resin-composites, including a series with systematically varied filler loading, plus other representative materials that fall into the categories of flowable, bulk-fill and conventional nano-hybrid types. Ten dental resin-composites: three flowable, three bulk-fill and four conventional were investigated using nanoindentation. Disc specimens (15mm×2mm) were prepared from each material using a metallic mold. Specimens were irradiated in the mold at top and bottom surfaces in multiple overlapping points (40s each) with light curing unit at 650mW/cm(2). Specimens were then mounted in 3cm diameter phenolic ring forms and embedded in a self-curing polystyrene resin. After grinding and polishing, specimens were stored in distilled water at 37°C for 7 days. Specimens were investigated using an Agilent Technologies XP nanoindenter equipped with a Berkovich diamond tip (100nm radius). Each specimen was loaded at one loading rate and three different unloading rates (at room temperature) with thirty indentations, per unloading rate. The maximum load applied by the nanoindenter to examine the specimens was 10mN. Dependent on the type of the resin-composite material, the mean values ranged from 0.73GPa to 1.60GPa for nanohardness and from 14.44GPa to 24.07GPa for elastic modulus. There was a significant positive non-linear correlation between elastic modulus and nanohardness (r(2)=0.88). Nonlinear regression revealed a significant positive correlation (r(2)=0.62) between elastic moduli and filler loading and a non-significant correlation (r(2)=0.50) between nanohardness and filler loading of the studied materials. Varying the unloading rates showed no consistent effect on the elastic modulus and nanohardness of the studied materials. For a specific resin matrix, both elastic moduli and nanohardness correlated positively with filler loading. For the resin-composites investigated, the group-average elastic

  8. Polishing and toothbrushing alters the surface roughness and gloss of composite resins.

    Science.gov (United States)

    Kamonkhantikul, Krid; Arksornnukit, Mansuang; Takahashi, Hidekazu; Kanehira, Masafumi; Finger, Werner J

    2014-01-01

    This study aimed to investigate the surface roughness and gloss of composite resins after using two polishing systems and toothbrushing. Six composite resins (Durafill VS, Filtek Z250, Filtek Z350 XT, Kalore, Venus Diamond, and Venus Pearl) were evaluated after polishing with two polishing systems (Sof-Lex, Venus Supra) and after toothbrushing up to 40,000 cycles. Surface roughness (Ra) and gloss were determined for each composite resin group (n=6) after silicon carbide paper grinding, polishing, and toothbrushing. Two-way ANOVA indicated significant differences in both Ra and gloss between measuring stages for the composite resins tested, except Venus Pearl, which showed significant differences only in gloss. After polishing, the Filtek Z350 XT, Kalore, and Venus Diamond showed significant increases in Ra, while all composite resin groups except the Filtek Z350 XT and Durafill VS with Sof-Lex showed increases in gloss. After toothbrushing, all composite resin demonstrated increases in Ra and decreases in gloss.

  9. Surface discoloration of composite resins: Effects of staining and bleaching

    Science.gov (United States)

    Poggio, Claudio; Beltrami, Riccardo; Scribante, Andrea; Colombo, Marco; Chiesa, Marco

    2012-01-01

    Background: The purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (Esthet•X HD, Clearfil AP-X, Gradia Direct) and five nanohybrid composite resins (Ceram•X, GC Kalore, G-aenial, Grandio, GrandioSO), after staining and bleaching procedures. Materials and Methods: The composite resins were polymerized with a curing light (Celalux II, Voco, Cuxhaven, Germany) into 160 silicon molds (6,4 mm in diameter and 2 mm in thickness) to obtain identical specimens. Twenty samples for each composite resin were prepared. The specimens were polished using an automated polishing machine with the sequence of 600-, 800-, 1000-grit abrasive paper under water irrigation. The specimens were immersed in tea and distilled water: the specimens were dipped for 20 min, once a day (every 24 h), for 14 days into the drinks. The specimens were then bleached with carbamide peroxide at 17% (Perfect Bleach-Voco). The color of specimens was measured with a spectrophotometer according to the CIE L*a*b* system after light-polymerization of composite resin specimens, after 7 days, after 14 days, and after bleaching. The color difference h index (DEab*) between each measurement was calculated. Statistical analysis was made using analysis of variance (ANOVA). Results: All specimens showed a significant increase in staining with a similar trend and no significant differences between microhybrid and nanohybrid composite resins. After whitening procedures, materials tested showed both significant and unsignificant differences of the h index. Conclusions: Microhybrid and nanohybrid composite resins had similar in vitro surface discoloration in tea. After bleaching, discoloration was removed from some composite resins tested. PMID:23559921

  10. Surface discoloration of composite resins: Effects of staining and bleaching

    Directory of Open Access Journals (Sweden)

    Claudio Poggio

    2012-01-01

    Full Text Available Background: The purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (Esthet·X HD, Clearfil AP-X, Gradia Direct and five nanohybrid composite resins (Ceram·X, GC Kalore, G-aenial, Grandio, GrandioSO, after staining and bleaching procedures. Materials and Methods: The composite resins were polymerized with a curing light (Celalux II, Voco, Cuxhaven, Germany into 160 silicon molds (6,4 mm in diameter and 2 mm in thickness to obtain identical specimens. Twenty samples for each composite resin were prepared. The specimens were polished using an automated polishing machine with the sequence of 600-, 800-, 1000-grit abrasive paper under water irrigation. The specimens were immersed in tea and distilled water: the specimens were dipped for 20 min, once a day (every 24 h, for 14 days into the drinks. The specimens were then bleached with carbamide peroxide at 17% (Perfect Bleach-Voco. The color of specimens was measured with a spectrophotometer according to the CIE LFNx01aFNx01bFNx01 system after light-polymerization of composite resin specimens, after 7 days, after 14 days, and after bleaching. The color difference h index (DE abFNx01 between each measurement was calculated. Statistical analysis was made using analysis of variance (ANOVA. Results: All specimens showed a significant increase in staining with a similar trend and no significant differences between microhybrid and nanohybrid composite resins. After whitening procedures, materials tested showed both significant and unsignificant differences of the h index. Conclusions: Microhybrid and nanohybrid composite resins had similar in vitro surface discoloration in tea. After bleaching, discoloration was removed from some composite resins tested.

  11. Surface discoloration of composite resins: Effects of staining and bleaching.

    Science.gov (United States)

    Poggio, Claudio; Beltrami, Riccardo; Scribante, Andrea; Colombo, Marco; Chiesa, Marco

    2012-09-01

    The purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (Esthet•X HD, Clearfil AP-X, Gradia Direct) and five nanohybrid composite resins (Ceram•X, GC Kalore, G-aenial, Grandio, GrandioSO), after staining and bleaching procedures. The composite resins were polymerized with a curing light (Celalux II, Voco, Cuxhaven, Germany) into 160 silicon molds (6,4 mm in diameter and 2 mm in thickness) to obtain identical specimens. Twenty samples for each composite resin were prepared. The specimens were polished using an automated polishing machine with the sequence of 600-, 800-, 1000-grit abrasive paper under water irrigation. The specimens were immersed in tea and distilled water: the specimens were dipped for 20 min, once a day (every 24 h), for 14 days into the drinks. The specimens were then bleached with carbamide peroxide at 17% (Perfect Bleach-Voco). The color of specimens was measured with a spectrophotometer according to the CIE L(*)a(*)b(*) system after light-polymerization of composite resin specimens, after 7 days, after 14 days, and after bleaching. The color difference h index (DEab(*)) between each measurement was calculated. Statistical analysis was made using analysis of variance (ANOVA). All specimens showed a significant increase in staining with a similar trend and no significant differences between microhybrid and nanohybrid composite resins. After whitening procedures, materials tested showed both significant and unsignificant differences of the h index. Microhybrid and nanohybrid composite resins had similar in vitro surface discoloration in tea. After bleaching, discoloration was removed from some composite resins tested.

  12. Synthesis and Characterization of Bio-Oil Phenol Formaldehyde Resin Used to Fabricate Phenolic Based Materials

    Directory of Open Access Journals (Sweden)

    Yong Cui

    2017-06-01

    Full Text Available In this study, bio-oil from the fast pyrolysis of renewable biomass was used as the raw material to synthesize bio-oil phenol formaldehyde (BPF resin—a desirable resin for fabricating phenolic-based material. During the synthesis process, paraformaldehyde was used to achieve the requirement of high solid content and low viscosity. The properties of BPF resins were tested. Results indicated that BPF resin with the bio-oil addition of 20% had good performance on oxygen index and bending strength, indicating that adding bio-oil could modify the fire resistance and brittleness of PF resin. The thermal curing behavior and heat resistance of BPF resins were investigated by differential scanning calorimetry (DSC and thermal gravimetric analysis (TGA. Results showed that adding bio-oil had an impact on curing characteristics and thermal degradation process of PF resin, but the influence was insignificant when the addition was relatively low. The chemical structure and surface characteristics of BPF resins were determined by Fourier transform infrared (FTIR spectroscopy and scanning electron microscopy (SEM. The analysis demonstrated that adding bio-oil in the amount of 20% was able to improve the crosslinking degree and form more hydrocarbon chains in PF resin.

  13. Enhancement of dispersion and adhesion of B4C particles in epoxy resin using direct ultrasonic excitation

    International Nuclear Information System (INIS)

    Jun, Jiheon; Kim, Jaewoo; Bae, Yeonjoo; Seo, Young Soo

    2011-01-01

    Highlights: → Enhanced adhesion and dispersion of B 4 C particles in epoxy resin was achieved. → FTIR spectrum was used for examination of B 4 C adhesion with epoxy resin. → Direct ultrasonic excitation causes enhanced surface treatment of B 4 C. → We developed an epoxy based neutron shield with higher mechanical properties. - Abstract: Enhancement of the mechanical properties of the B 4 C/epoxy composites, which is used as a neutron shield for spent nuclear fuel cask, was achieved by direct ultrasonic dispersion of the B 4 C particles in the hardener using an immersed horn, while those prepared without direct ultrasonic dispersion showed insufficient adhesion as well as some agglomerates in the epoxy resin. Degrees of agglomeration and adhesion were analyzed by means of the SEM images and the FTIR peaks belong to C-C stretching mode of the hardener ring, which was lowered and flattened by van der Waals interaction between the B 4 C particles and the hardener ring substituent. The tensile strength of the B 4 C/epoxy composites prepared by direct ultrasonic dispersion was maintained (or increased) compared to that for the neat epoxy matrix, while those prepared without ultrasonic dispersion were degraded significantly. Consequently, direct ultrasonic dispersion process developed in this investigation could achieve uniform dispersion as well as strong adhesion of the B 4 C particles in/with the epoxy matrix enhancing the material properties without any chemical treatment resulting unwanted impurities.

  14. Influence of Surface Modifications of Acrylic Resin Teeth on Shear Bond Strength with Denture Base Resin-An Invitro Study.

    Science.gov (United States)

    Mahadevan, Vallabh; Krishnan, Madhusudan; Krishnan, Chitra Shankar; Azhagarasan, N S; Sampathkumar, Jayakrishnakumar; Ramasubramanian, Hariharan

    2015-09-01

    Debonding of artificial teeth from the denture base is an important issue for edentulous patients rehabilitated with conventional or implant supported complete dentures. The purpose of this study was to evaluate shear bond strength between denture base resin and acrylic resin denture teeth subjected to three different surface modifications on the ridge lap area as compared to unmodified denture teeth. Forty acrylic resin central incisor denture teeth were selected and randomly divided into four test groups. The teeth in each group were subjected to one of the three different surface modifications, namely, chemical treatment, sandblasting and placement of retentive grooves on the ridge lap area respectively, prior to packing of the denture base resin. The group with unmodified teeth served as control. Forty acrylic resin test blocks thus obtained were tested for shear bond strength between acrylic resin teeth and denture base resin in Universal Testing Machine. Data obtained was statistically analysed using one-way ANOVA and Student- Newman- Keul's test (p< 0.05). Analysis of shear bond strength revealed that retentive grooves on the ridge lap area showed highest bond strength values followed by sandblasting and both were statistically significant compared to the control and chemically treated groups. Unmodified surface of the resin teeth showed the least bond strength. Within the limitations of this invitro study the placement of retentive grooves or sandblasting of the ridge lap area showed highly significant improvement in shear bond strength compared to the unmodified surface. Chemical treatment did not result in any significant improvement in the shear bond strength compared to the unmodified surface.

  15. Influence of Surface Modifications of Acrylic Resin Teeth on Shear Bond Strength with Denture Base Resin-An Invitro Study

    Science.gov (United States)

    Krishnan, Madhusudan; Krishnan, Chitra Shankar; Azhagarasan, N.S.; Sampathkumar, Jayakrishnakumar; Ramasubramanian, Hariharan

    2015-01-01

    Background Debonding of artificial teeth from the denture base is an important issue for edentulous patients rehabilitated with conventional or implant supported complete dentures. Aim The purpose of this study was to evaluate shear bond strength between denture base resin and acrylic resin denture teeth subjected to three different surface modifications on the ridge lap area as compared to unmodified denture teeth. Materials and Methods Forty acrylic resin central incisor denture teeth were selected and randomly divided into four test groups. The teeth in each group were subjected to one of the three different surface modifications, namely, chemical treatment, sandblasting and placement of retentive grooves on the ridge lap area respectively, prior to packing of the denture base resin. The group with unmodified teeth served as control. Forty acrylic resin test blocks thus obtained were tested for shear bond strength between acrylic resin teeth and denture base resin in Universal Testing Machine. Data obtained was statistically analysed using one-way ANOVA and Student- Newman- Keul’s test (p< 0.05). Results Analysis of shear bond strength revealed that retentive grooves on the ridge lap area showed highest bond strength values followed by sandblasting and both were statistically significant compared to the control and chemically treated groups. Unmodified surface of the resin teeth showed the least bond strength. Conclusion Within the limitations of this invitro study the placement of retentive grooves or sandblasting of the ridge lap area showed highly significant improvement in shear bond strength compared to the unmodified surface. Chemical treatment did not result in any significant improvement in the shear bond strength compared to the unmodified surface. PMID:26501005

  16. [Acrylic resin removable partial dentures].

    Science.gov (United States)

    de Baat, C; Witter, D J; Creugers, N H J

    2011-01-01

    An acrylic resin removable partial denture is distinguished from other types of removable partial dentures by an all-acrylic resin base which is, in principle, solely supported by the edentulous regions of the tooth arch and in the maxilla also by the hard palate. When compared to the other types of removable partial dentures, the acrylic resin removable partial denture has 3 favourable aspects: the economic aspect, its aesthetic quality and the ease with which it can be extended and adjusted. Disadvantages are an increased risk of caries developing, gingivitis, periodontal disease, denture stomatitis, alveolar bone reduction, tooth migration, triggering of the gag reflex and damage to the acrylic resin base. Present-day indications are ofa temporary or palliative nature or are motivated by economic factors. Special varieties of the acrylic resin removable partial denture are the spoon denture, the flexible denture fabricated of non-rigid acrylic resin, and the two-piece sectional denture. Furthermore, acrylic resin removable partial dentures can be supplied with clasps or reinforced by fibers or metal wires.

  17. Analysis of surface hardness of artificially aged resin composites

    Directory of Open Access Journals (Sweden)

    Denise Cremonezzi Tornavoi

    2012-02-01

    Full Text Available This study evaluated the effect of artificially accelerated aging (AAA on the surface hardness of eight composite resins: Filtek Z250, Filtek Supreme, 4 Seasons, Herculite, P60, Tetric Ceram, Charisma, and Filtek Z100. Sixteen specimens were made from the test piece of each material, using an 8.0 × 2.0 mm teflon matrix. After 24 hours, eight specimens from each material were submitted to three surface hardness readings using a Shimadzu Microhardness Tester for 5 seconds at a load of 50 gf. The other eight specimens remained in the artificially accelerated aging machine for 382 hours and were submitted to the same surface hardness analysis. The means of each test specimen were submitted to the Kolmogorov-Smirnov test (p > 0.05, ANOVA and Tukey test (p < 0.05. With regard to hardness (F = 86.74, p < 0.0001 the analysis showed significant differences among the resin composite brands. But aging did not influence the hardness of any of the resin composites (F = 0.39, p = 0.53. In this study, there was interaction between the resin composite brand and the aging factors (F = 4.51, p < 0.0002. It was concluded that notwithstanding the type of resin, AAA did not influence surface hardness. However, with regard to hardness there was a significant difference among the resin brands.

  18. Interactions of natural resins and pigments in works of art.

    Science.gov (United States)

    Poli, Tommaso; Piccirillo, Anna; Nervo, Marco; Chiantore, Oscar

    2017-10-01

    The degradation process involving the formation of metal soaps in drying oils is a well-known problem due to cations from pigments reacting with free fatty acids from the oil. The aggregation of these carboxylates in semi-crystalline structures can lead to eruptions through the paint layers and 'blooming' on the surface. In this work, the metal soaps formation in presence of natural resins has been assessed and studied by means of Fourier transform infrared spectroscopy with experiments concerning the ageing of drying oil and different natural resins (shellac, dammar and colophony) in the presence of common historic pigments (smalt, ochre, umber, azurite, lead white, zinc white and titanium white). Mixtures of resins and pigments have been exposed to photo-ageing in solar box up to 1000h, thermal ageing at 50°C up to 1100h and 6month of room conditions exposure as reference. The decrease in the intensity of the carbonyl band in the spectra, as well as the contemporary increase of the metal carboxylates (in the range from 1500 to 1650cm -1 ) absorption bands, were used as the main indicators of metal soap formation. It has been observed that some pigments, particularly zinc white and smalt, present a 'catalytic' effect favouring the simultaneous formation of associated oxalates. The formation of oxalates and different degradation products from natural resins in the presence of pigments is particularly important, as it deeply affects the removability of varnishes and, more generally, the cleaning processes. Moreover, it permanently modifies the interface between painting and varnish layers as well as the aesthetic aspects of the painted surfaces. The influence of natural resins reactivity with pigments and their role in the oxalate formation is an issue still unexplored. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Chromatography resin support

    Science.gov (United States)

    Dobos, James G.

    2002-01-01

    An apparatus and method of using an improved chromatography resin support is disclosed. The chromatography support platform is provided by a stainless steel hollow cylinder adapted for being inserted into a chromatography column. An exterior wall of the stainless steel cylinder defines a groove for carrying therein an "O"-ring. The upper surface of the stainless steel column is covered by a fine stainless steel mesh welded to the edges of the stainless steel cylinder. When placed upon a receiving ledge defined within a chromatography column, the "O"-ring provides a fluid tight seal with the inner edge wall of the chromatography cylinder. The stainless steel mesh supports the chromatography matrix and provides a back flushable support which is economical and simple to construct.

  20. 21 CFR 872.3140 - Resin applicator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Resin applicator. 872.3140 Section 872.3140 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3140 Resin applicator. (a) Identification. A resin applicator is a brushlike device intended for use in spreading dental resin on a tooth during application of...

  1. High Temperature Degradation of 5250-4 Polymer Resin

    National Research Council Canada - National Science Library

    Link, Patrick E

    2007-01-01

    .... Isothermal thermo-gravimetric analysis demonstrated that weight loss was negligible for aging in the argon environment, indicating weight loss is the result of an oxidative process at these temperatures...

  2. Influence of denture cleansers on the color stability of three types of denture base acrylic resin.

    Science.gov (United States)

    Hong, Guang; Murata, Hiroshi; Li, YingAi; Sadamori, Sinshuke; Hamada, Taizo

    2009-03-01

    Color stability is an important property of denture base acrylic resin. Color changes indicate aging or damaged dental materials. However, little information is available on the influence of denture cleansers on the color stability of acrylic resins. The purpose of this study was to determine the influence of denture cleansers on the color stability of 3 different types of acrylic resin. One heat-polymerized (HP) acrylic denture base resin (Acron), 1 autopolymerized (AP) hard direct reline acrylic resin (Denture Liner), and 1 visible-light-polymerized (VLP) hard direct reline acrylic resin (Tokuso Lite-Rebase) were evaluated. Five specimens of each material, 10 x 10 x 2 mm, were immersed in 1 of 9 commercial denture cleanser solutions or distilled water (control). Color changes were measured with a colorimeter and evaluated using the CIE L*a*b* colorimetric system. Data were analyzed using 1-way and 3-way ANOVA and the Student-Newman-Keuls test (alpha=.05). Significant differences (P<.05) were found among the acrylic resins and denture cleansers in terms of color change (DeltaE) produced after 365 days. The DeltaE values of all denture base acrylic resins increased with time. The DeltaE of the AP acrylic resin was larger than that of the other acrylic resins. The least discoloration was found with ZTC denture cleanser (acid type). The influence of alkaline peroxide-type denture cleanser (Steradent) on the color stability of HP acrylic resin and AP acrylic resin was significantly greater (P<.05) than that of the other cleansers. These results suggest that the color stability of denture base acrylic resins is influenced by polymerization type and the type of denture cleanser used.

  3. Bacterial adhesion on direct and indirect dental restorative composite resins: An in vitro study on a natural biofilm.

    Science.gov (United States)

    Derchi, Giacomo; Vano, Michele; Barone, Antonio; Covani, Ugo; Diaspro, Alberto; Salerno, Marco

    2017-05-01

    Both direct and indirect techniques are used for dental restorations. Which technique should be preferred or whether they are equivalent with respect to bacterial adhesion is unclear. The purpose of this in vitro study was to determine the affinity of bacterial biofilm to dental restorative composite resins placed directly and indirectly. Five direct composite resins for restorations (Venus Diamond, Adonis, Optifil, Enamel Plus HRi, Clearfil Majesty Esthetic) and 3 indirect composite resins (Gradia, Estenia, Signum) were selected. The materials were incubated in unstimulated whole saliva for 1 day. The biofilms grown were collected and their bacterial cells counted. In parallel, the composite resin surface morphology was analyzed with atomic force microscopy. Both bacterial cell count and surface topography parameters were subjected to statistical analysis (α=.05). Indirect composite resins showed significantly lower levels than direct composite resins for bacterial cell adhesion, (Pcomposite resins (P>.05). However, within the indirect composite resins a significantly lower level was found for Gradia than Estenia or Signum (Pcomposite resin roughness and bacterial adhesion when the second and particularly the third-order statistical moments of the composite resin height distributions were considered. Indirect dental restorative composite resins were found to be less prone to biofilm adhesion than direct composite resins. A correlation of bacterial adhesion to surface morphology exists that is described by kurtosis; thus, advanced data analysis is required to discover possible insights into the biologic effects of morphology. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  4. Microhardness of dual-polymerizing resin cements and foundation composite resins for luting fiber-reinforced posts.

    Science.gov (United States)

    Yoshida, Keiichi; Meng, Xiangfeng

    2014-06-01

    The optimal luting material for fiber-reinforced posts to ensure the longevity of foundation restorations remains undetermined. The purpose of this study was to evaluate the suitability of 3 dual-polymerizing resin cements and 2 dual-polymerizing foundation composite resins for luting fiber-reinforced posts by assessing their Knoop hardness number. Five specimens of dual-polymerizing resin cements (SA Cement Automix, G-Cem LincAce, and Panavia F2.0) and 5 specimens of dual-polymerizing foundation composite resins (Clearfil DC Core Plus and Unifil Core EM) were polymerized from the top by irradiation for 40 seconds. Knoop hardness numbers were measured at depths of 0.5, 2.0, 4.0, 6.0, 8.0, and 10.0 mm at 0.5 hours and 7 days after irradiation. Data were statistically analyzed by repeated measures ANOVA, 1-way ANOVA, and the Tukey compromise post hoc test (α=.05). At both times after irradiation, the 5 resins materials showed the highest Knoop hardness numbers at the 0.5-mm depth. At 7 days after irradiation, the Knoop hardness numbers of the resin materials did not differ significantly between the 8.0-mm and 10.0-mm depths (P>.05). For all materials, the Knoop hardness numbers at 7 days after irradiation were significantly higher than those at 0.5 hours after irradiation at all depths (Presin materials were found to decrease in the following order: DC Core Plus, Unifil Core EM, Panavia F2.0, SA Cement Automix, and G-Cem LincAce (Pcomposite resins were higher than those of the 3 dual-polymerizing resin cements, notable differences were seen among the 5 materials at all depths and at both times after irradiation. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  5. Effect of adherend temperature on bond strengths of resin bonding systems to denture base resin and a semi-precious alloy.

    Science.gov (United States)

    Murahara, Sadaaki; Minami, Hiroyuki; Suzuki, Shiro; Sakoguchi, Kenji; Shiomuki, Daisaku; Minesaki, Yoshito; Tanaka, Takuo

    2013-01-01

    This study investigated the effect of adherend temperature on shear bond strengths of auto-polymerizing resin to denture base resin and 4-META/MMA-TBBO resin to silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy. Bonding procedure was carried out when adherend temperature was 10, 23, 37, or 55°C, and shear bond strengths (SBSs) were measured before and after thermocycling. Before thermocycling, there were no significant differences in bond strength among the four adherend temperatures for each adhesive resin: 31.59±6.11-32.89±2.12 MPa for auto-polymerizing resin; 35.43±2.2-38.38±0.61 MPa for 4-META/MMA-TBBO resin. After thermocycling, optimal adherend temperature to achieve the highest bond strength was 37°C for auto-polymerizing resin to denture base resin (30.02±2.29 MPa) and 10ºC for 4-META/MMA-TBBO resin to Ag-Pd-Cu-Au alloy (37.14±2.17 MPa).

  6. Effects of Prepolymerized Particle Size and Polymerization Kinetics on Volumetric Shrinkage of Dental Modeling Resins

    Directory of Open Access Journals (Sweden)

    Tae-Yub Kwon

    2014-01-01

    Full Text Available Dental modeling resins have been developed for use in areas where highly precise resin structures are needed. The manufacturers claim that these polymethyl methacrylate/methyl methacrylate (PMMA/MMA resins show little or no shrinkage after polymerization. This study examined the polymerization shrinkage of five dental modeling resins as well as one temporary PMMA/MMA resin (control. The morphology and the particle size of the prepolymerized PMMA powders were investigated by scanning electron microscopy and laser diffraction particle size analysis, respectively. Linear polymerization shrinkage strains of the resins were monitored for 20 minutes using a custom-made linometer, and the final values (at 20 minutes were converted into volumetric shrinkages. The final volumetric shrinkage values for the modeling resins were statistically similar (P>0.05 or significantly larger (P<0.05 than that of the control resin and were related to the polymerization kinetics (P<0.05 rather than the PMMA bead size (P=0.335. Therefore, the optimal control of the polymerization kinetics seems to be more important for producing high-precision resin structures rather than the use of dental modeling resins.

  7. Diametral tensile strength of four composite resin core materials with and without centered fiber dowels.

    Science.gov (United States)

    Driessen, Cornel H; Ji, Donatta Y-J; Rizkalla, Amin S; Santos, Gildo C

    2011-01-01

    This study evaluated the diametral tensile strength of composite resin core materials with and without fiber dowels. Eight groups were established (n = 20), four with composite resins and four with fiber dowels. Samples were tested using a universal testing machine and evaluated using scanning electron microscopy. One-way ANOVA and a Tukey B-rank order test (P = 0.05) indicated that the tensile values of two of the four composite resins decreased significantly when their matching fiber dowels were introduced.

  8. Improved thermal stability of methylsilicone resins by compositing with N-doped graphene oxide/Co3O4 nanoparticles

    International Nuclear Information System (INIS)

    Jiang, Bo; Zhao, Liwei; Guo, Jiang; Yan, Xingru; Ding, Daowei; Zhu, Changcheng; Huang, Yudong; Guo, Zhanhu

    2016-01-01

    Nanoparticles play important roles in enhancing the thermal-resistance of hosting polymer resins. Despite tremendous efforts, developing thermally stable methylsilicone resin at high temperatures is still a challenge. Herein, we report a strategy to increase the activation energy to slow down the decomposition/degradation of methylsilicone resin using synergistic effects between the Co 3 O 4 nanoparticles and the nitrogen doped graphene oxide. The N-doped graphene oxides composited with Co 3 O 4 nanoparticles were prepared by hydrolysis of cobalt nitrate hexahydrate in the presence of graphene oxide and were incorporated into the methylsilicone resin. Two-stage decompositions were observed, i.e., 200–300 and 400–500 °C. The activation energy for the low temperature region was enhanced by 47.117 kJ/mol (vs. 57.76 kJ/mol for pure resin). The enhanced thermal stability was due to the fact that the nanofillers prevented the silicone hydroxyl chain ends ‘‘biting’’ to delay the degradation. The activation energy for high-temperature region was enhanced by 11.585 kJ/mol (vs. 171.95 kJ/mol for pure resin). The nanofillers formed a protective layer to isolate oxygen from the hosting resin. The mechanism for the enhanced thermal stability through prohibited degradation with synergism of these nitrogen-doped graphene oxide nanocomposites was proposed as well.Graphical Abstract

  9. Ultraviolet light and ultraviolet light-activated composite resins

    International Nuclear Information System (INIS)

    Murray, G.A.; Yates, J.L.; Newman, S.M.

    1981-01-01

    In a comparison of the UV light--activated composite resins, Estilux was polymerized to a significantly greater depth than the other composite resins. In general, Lee-fill polymerized the least. When comparing the UV light sources, the Lee light and the Duralux light did not significantly differ from each other, but both polymerized the materials tested to a significantly greater depth than the other light sources. Of the two time exposures, 60-second exposure provided a significantly greater depth of polymerization than 20 seconds for each light with each material

  10. and phenol–formaldehyde resin

    Indian Academy of Sciences (India)

    formaldehyde resin (PFR) modified with tetraethylorthosilicate are investigated in detail. The chemical synthesis of PFR, its modification with nanometer- sized SiO2 particles created by sol–gel method and subsequent coating, enables a preparation of ...

  11. HIGH ASPECT RATIO ION EXCHANGE RESIN BED - HYDRAULIC RESULTS FOR SPERICAL RESIN BEADS

    International Nuclear Information System (INIS)

    Duignan, M; Charles Nash, C; Timothy Punch, T

    2007-01-01

    A principal role of the DOE Savannah River Site is to safely dispose of a large volume of liquid nuclear waste held in many storage tanks. An in-tank ion exchange unit is being considered for cesium removal to accelerate waste processing. This unit is planned to have a relatively high bed height to diameter ratio (10:1). Complicating the design is the need to cool the ion exchange media; therefore, the ion exchange column will have a central cooling core making the flow path annular. To separate cesium from waste the media being considered is made of resorcinol formaldehyde resin deposited on spherical plastic beads and is a substitute for a previously tested resin made of crystalline silicotitanate. This spherical media not only has an advantage of being mechanically robust, but, unlike its predecessor, it is also reusable, that is, loaded cesium can be removed through elution and regeneration. Resin regeneration leads to more efficient operation and less spent resin waste, but its hydraulic performance in the planned ion exchange column was unknown. Moreover, the recycling process of this spherical resorcinol formaldehyde causes its volume to significantly shrink and swell. To determine the spherical media's hydraulic demand a linearly scaled column was designed and tested. The waste simulant used was prototypic of the wastes' viscosity and density. This paper discusses the hydraulic performance of the media that will be used to assist in the design of a full-scale unit

  12. Solidifying process and flame retardancy of epoxy resin cured with boron-containing phenolic resin

    Science.gov (United States)

    Deng, Peng; Shi, Yan; Liu, Yuansen; Liu, Yuan; Wang, Qi

    2018-01-01

    For the sake of improving the charring performance and flame retardancy of epoxy resin (EP), boron-containing phenolic resin (BPR) instead of a conventional curing agent, linear phenolic resin (LPR) was employed to cure EP. Of several possible chemical structures for BPR, the existence of benzyl hydroxy groups in BPR chains has been confirmed using 1H nuclear magnetic resonance spectroscopy. The resonance of these groups may reasonably explain the higher curing reactivity of BPR-cured EP than that of LPR-cured EP. Thermogravimetric analysis, observation of the morphologies of the char residues and X-ray photoelectron spectroscopic were performed to characterize the charring process. Due to the presence of B2O3 produced on the char surface from decomposition of phenyl borates and the facile high self-crosslinking reaction of BPR, a more continuous and stronger char barrier was formed for BPR-cured EP compared to that for the LPR-cured EP system. Therefore the former exhibited much better flame retardancy. In addition, BPR-cured EP also displayed better dynamic mechanical properties, than those observed for LPR-cured EP. It is not subject to the significant lowering the glass transition temperature of the polymer which accompanies curing with LPR. This suggests that BPR cured resin may meet the requirement for utilization at high temperature.

  13. Marginal adaptation of composite resins under two adhesive techniques.

    Science.gov (United States)

    Dačić, Stefan; Veselinović, Aleksandar M; Mitić, Aleksandar; Nikolić, Marija; Cenić, Milica; Dačić-Simonović, Dragica

    2016-11-01

    In the present research, different adhesive techniques were used to set up fillings with composite resins. After the application of etch and rinse or self etch adhesive technique, marginal adaptation of composite fillings was estimated by the length of margins without gaps, and by the microretention of resin in enamel and dentin. The study material consisted of 40 extracted teeth. Twenty Class V cavities were treated with 35% phosphorous acid and restored after rinsing by Adper Single Bond 2 and Filtek Ultimate-ASB/FU 3M ESPE composite system. The remaining 20 cavities were restored by Adper Easy One-AEO/FU 3M ESPE composite system. Marginal adaptation of composite fillings was examined using a scanning electron microscope (SEM). The etch and rinse adhesive technique showed a significantly higher percentage of margin length without gaps (in enamel: 92.5%, in dentin: 57.3%), compared with the self-etch technique with lower percentage of margin length without gaps, in enamel 70.4% (p resin tugs in interprismatic spaces of enamel, while the dentin microretention was composed of adhesive and hybrid layers with resin tugs in dentin canals. In the second technique, resin tugs were rarely seen and a microgap was dominant along the border of restoration margins. The SEM analysis showed a better marginal adaptation of composite resin to enamel and dentin with better microretention when the etch and rinse adhesive procedure was applied. © 2016 Wiley Periodicals, Inc.

  14. Pengaruh Minuman Kopi terhadap Perubahan Warna pada Resin Komposit

    Directory of Open Access Journals (Sweden)

    Aprilia Aprilia

    2015-10-01

    Full Text Available Objective: The aim of this research was to investigate the influence of coffee beverage on hybrid composite resin discoloration. Material and method: This study used hybrid composite resin with A3 color, and was done by soaking composite resin plates in coffee solution for 1, 3, 5, and 7 days, corresponding to equivalent coffee usage for 6 months, 1, 1.5, and 2 years. The same measurements of reflectance were done before and after soaking into coffee solution. In the measurement, a beam from He-Ne laser is reflected by the sample to a photovoltaic cell type BOY-47, which provides a voltage signal accordig to the intensity of reflected light. Results: There was a significant difference between composite resin plates before and after soaking into coffee dilution for 1, 3, 5, and 7 days. Conclusion: Composite resin is discolored after soaking into a coffee solution, suggesting that coffee usage will have a discoloring effect on dental composite resin.

  15. Urea-formaldehyde resins: production, application, and testing

    Science.gov (United States)

    Nuryawan, A.; Risnasari, I.; Sucipto, T.; Heri Iswanto, A.; Rosmala Dewi, R.

    2017-07-01

    Urea-formaldehyde (UF) resin, one of the most important formaldehyde resin adhesives, is a polymeric condensation product of formaldehyde with urea, and being widely used for the manufacture of wood-based composite panels, such as plywood, particleboard, and fiberboard. In spite of its benefits such as fast curing, good performance in the panels (colorless), and lower cost; formaldehyde emission (FE) originated from either UF resin itself or composite products bonded by UF resins is considered a critical drawback as it affects human health particularly in indoor environment. In order to reduce the FE, lowering formaldehyde/urea (F/U) mole ratio in the synthesis of the UF resin was done. In this study, synthesis of UF resins was carried out following the conventional alkaline-acid two-step reaction with a second addition of urea, resulting in F/U mole ratio around 1.0, namely 0.95; 1.05, and 1.15. The UF resins produced were used as binder for particleboard making. The board was manufactured in the laboratory using shaving type particle of Gmelina wood, 8% UF resin based on oven dry particle, and 1% NH4Cl (20%wt) as hardener for the resin. The target of the thickness was 10 mm and the dimension was 25 cm x 25 cm. The resulted particleboard then was evaluated the physical and the mechanical properties by Japanese Industrial Standard (JIS) A 5908 (2003). Further, the resulted particleboard also was used for the mice cage’s wall in order to mimic the real living environment. After four weeks exposure in the cages, the mice then were evaluated their mucous organs as well as their blood. The experiment results were as follows: 1) It was possible to synthesis UF resins with low F/U mole ratio; 2) However, the particleboard bonded UF resins with low F/U mole ratio showed poor properties, particularly on the thickness swelling and modulus of elasticity; 3) There was no significant differences among the mucous organs of the mice after a month exposure FE originated from

  16. Resin glycosides from Porana duclouxii.

    Science.gov (United States)

    Ding, Wen-Bing; Zhang, Dai-Gui; Liu, Chun-Jie; Li, Guan-Hua; Li, You-Zhi

    2014-01-01

    A new intact resin glycoside (3) and two glycosidic acids (1 and 2), all having a common trisaccharide moiety and (11S)-hydroxytetradecanoic acid or (3S,11S)-dihydroxytetradecanoic acid as the aglycone, were obtained from the roots of Porana duclouxii. Their structures were elucidated by spectroscopic analyses and chemical correlations. These compounds represent the first examples of resin glycosides from the genus Porana.

  17. Liquid monobenzoxazine based resin system

    Science.gov (United States)

    Tietze, Roger; Nguyen, Yen-Loan; Bryant, Mark

    2014-10-07

    The present invention provides a liquid resin system including a liquid monobenzoxazine monomer and a non-glycidyl epoxy compound, wherein the weight ratio of the monobenzoxazine monomer to the non-glycidyl epoxy compound is in a range of about 25:75 to about 60:40. The liquid resin system exhibits a low viscosity and exceptional stability over an extended period of time making its use in a variety of composite manufacturing methods highly advantageous.

  18. Studies on the radiation chemistry of biomolecules in aqueous solution with specific objective of minimizing their radiolytic degradation. Coordinated programme for Asia and the Pacific Region on radiation sterilization practices significant to local medical supplies and conditions

    International Nuclear Information System (INIS)

    Narayana Rao, K.

    1979-01-01

    As part of a study of radiolytic degradation of pharmaceuticals during radiosterilization, the basic radiation chemistry of the B-group vitamins, nicotinamide, pyridoxin, riboflavin and thiamine, and the reaction of hydrogen peroxide with these same materials has been investigated. The various aspects studied were - radiolysis under controlled conditions, effects of phase, temperature, pH and nature and concentration of additives. Some of the conclusions are: 1) with oxygen saturated aqueous solutions containing glucose, the radiolytic degradation of the vitamins is reduced: 2) results a similar for N 2 O saturated aqueous solutions; 3) in glucose-containing solutions, the protective effect is considerably modified at higher temperatures; and 4) irradiation of air-saturated aqueous solutions in the frozen state leads to reduced decomposition. It is concluded that in the presence of oxygen, in frozen matrices at low temperature, it appears possible to reduce the radiolytic breakdown of vitamins to low levels

  19. Characteristics of resin floc dispersion of anion and cation exchange resin in precoat filter using powdered ion exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Tetsurou (Nitto Denko Corp., Ibaraki, Osaka (Japan)); Sawa, Toshio; Shindoh, Toshikazu

    1989-09-01

    The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of resin floc dispersion. The factors related to resin floc dispersion of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index in addition to the measurement of physical, chemical and electrochemical properties of powdered ion exchange resin. The effect of adsorption of iron oxide and polymer electrolyte and of ion exchange were determined. In addition, considered floc dispersion with adsorbing iron oxide, it was assumed that the amount and filling ratio of resin floc were related to summation and multiplication of surface electric charge respectively. An experimental expression was obtained for simulation of the change of specific settle volume of resin floc by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author).

  20. Characteristics of resin floc dispersion of anion and cation exchange resin in precoat filter using powdered ion exchange resin

    International Nuclear Information System (INIS)

    Adachi, Tetsurou; Sawa, Toshio; Shindoh, Toshikazu.

    1989-01-01

    The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of resin floc dispersion. The factors related to resin floc dispersion of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index in addition to the measurement of physical, chemical and electrochemical properties of powdered ion exchange resin. The effect of adsorption of iron oxide and polymer electrolyte and of ion exchange were determined. In addition, considered floc dispersion with adsorbing iron oxide, it was assumed that the amount and filling ratio of resin floc were related to summation and multiplication of surface electric charge respectively. An experimental expression was obtained for simulation of the change of specific settle volume of resin floc by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author)

  1. Polymerization Behavior and Mechanical Properties of High-Viscosity Bulk Fill and Low Shrinkage Resin Composites.

    Science.gov (United States)

    Shibasaki, S; Takamizawa, T; Nojiri, K; Imai, A; Tsujimoto, A; Endo, H; Suzuki, S; Suda, S; Barkmeier, W W; Latta, M A; Miyazaki, M

    The present study determined the mechanical properties and volumetric polymerization shrinkage of different categories of resin composite. Three high viscosity bulk fill resin composites were tested: Tetric EvoCeram Bulk Fill (TB, Ivoclar Vivadent), Filtek Bulk Fill posterior restorative (FB, 3M ESPE), and Sonic Fill (SF, Kerr Corp). Two low-shrinkage resin composites, Kalore (KL, GC Corp) and Filtek LS Posterior (LS, 3M ESPE), were used. Three conventional resin composites, Herculite Ultra (HU, Kerr Corp), Estelite ∑ Quick (EQ, Tokuyama Dental), and Filtek Supreme Ultra (SU, 3M ESPE), were used as comparison materials. Following ISO Specification 4049, six specimens for each resin composite were used to determine flexural strength, elastic modulus, and resilience. Volumetric polymerization shrinkage was determined using a water-filled dilatometer. Data were evaluated using analysis of variance followed by Tukey's honestly significant difference test (α=0.05). The flexural strength of the resin composites ranged from 115.4 to 148.1 MPa, the elastic modulus ranged from 5.6 to 13.4 GPa, and the resilience ranged from 0.70 to 1.0 MJ/m 3 . There were significant differences in flexural properties between the materials but no clear outliers. Volumetric changes as a function of time over a duration of 180 seconds depended on the type of resin composite. However, for all the resin composites, apart from LS, volumetric shrinkage began soon after the start of light irradiation, and a rapid decrease in volume during light irradiation followed by a slower decrease was observed. The low shrinkage resin composites KL and LS showed significantly lower volumetric shrinkage than the other tested materials at the measuring point of 180 seconds. In contrast, the three bulk fill resin composites showed higher volumetric change than the other resin composites. The findings from this study provide clinicians with valuable information regarding the mechanical properties and

  2. Silicone Resin Applications for Ceramic Precursors and Composites

    Directory of Open Access Journals (Sweden)

    Masaki Narisawa

    2010-06-01

    Full Text Available This article reviews the applications of silicone resins as ceramic precursors. The historical background of silicone synthesis chemistry is introduced to explain the production costs and supply availability of various silicones. Thermal degradation processes of silicones are classified in terms of the main chain structure and cyclic oligomer expulsion process, which determine the resulting ceramic yield and the chemical composition. The high temperature decomposition of Si-O-C beyond 1,400 °C in an inert atmosphere and formation of a protective silica layer on material surfaces beyond 1,200 °C in an oxidative atmosphere are discussed from the viewpoints of the wide chemical composition of the Si-O-C materials. Applications of the resins for binding agents, as starting materials for porous ceramics, matrix sources with impregnation, fiber spinning and ceramic adhesions are introduced. The recent development of the process of filler or cross-linking agent additions to resin compounds is also introduced. Such resin compounds are useful for obtaining thick coatings, MEMS parts and bulk ceramics, which are difficult to obtain by pyrolysis of simple organometallic precursors without additives.

  3. Comparison of the Amount of Fluoride Release from Nanofilled Resin Modified Glass Ionomer Conventional and Resin Modified Glass Ionomer Cements

    Directory of Open Access Journals (Sweden)

    Sumitha Upadhyay

    2013-01-01

    Full Text Available Objective: To investigate and compare the amount of fluoride release of conventional, resin modified and nanofilled resin modified glass ionomer cements.Materials and Methods: Tablets of glass-ionomer cements were immersed in deionized water and incubated at 37◦C. After 1, 2, 7, 15 and 30 days, fluoride ion was measured under normal atmospheric conditions by fluoride ion selective electrode. Buffer (TISAB II was used to decomplex the fluoride ion and to provide a constant background ionic strength and to maintain the pH of water between 5.0 and 5.5 as the fluoride electrode is sensitive to changes in pH. Statistical evaluation was carried out by one way ANOVA (Analysis of Variance using SPSS 11.0. The significance level was set at p< 0.05.Results: The release of fluoride was highest on day 1 and there was a sudden fall on day 2 in all three groups. Initially fluoride release from conven-tional glass-ionomer cement was highest compared to the other two glass-ionomer cements, but the amount drastically reduced over the period. Although the amount of fluoride release was less than both the resin modified and nanofilled resin modified glass-ionomer cement, the release was sustained consistently for 30 daysConclusion: The cumulative fluoride release of nanofilled resin modified glass ionomer cement was very less compared to the conventional and resin modified glass ionomer cements and Nanofilled resin modified glass ionomer cement released less but steady fluoride as compared to other resin modified glass ionomer cements.

  4. Comparison of extracted teeth and simulated resin blocks on apical canal transportation.

    Science.gov (United States)

    Khalilak, Zohreh; Fallahdoost, Arjang; Dadresanfar, Bahareh; Rezvani, Gholamreza

    2008-01-01

    We aimed to compare apical canal transportation of extracted teeth and two types of simulated resin blocks. Mesiobuccal root of extracted maxillary molars, high hardness simulated resin blocks (Knoop hardness=40) and low hardness simulated resin blocks (Knoop hardness=22) were prepared with K-files using step-back technique (n=15 canals in each group). Double exposure radiographic technique was used for extracted teeth. Simulated resin blocks were stabilized and scanned before and after preparation. Pre and post-preparation pictures were superimposed and apical transportation was measured. The data were analyzed statistically using ANOVA and Tukey HSD tests. There was no significant difference in apical canal transportation between extracted teeth and high hardness resin blocks (P>0.05). Low hardness resin blocks showed more apical transportation than the other groups (Presin blocks were similar.

  5. Effect of water storage on resin-dentin bond strengths formed by different bonding approaches

    Directory of Open Access Journals (Sweden)

    Martins G

    2009-01-01

    Full Text Available Objectives: The purpose of this study was to evaluate the influence of water storage on resin-dentin bond strengths [µTBS] using different adhesive bonding approaches. Materials and Methods: Flat superficial dentin surfaces of 24 extracted human third molars were exposed and polished to create a standardized smear layer. The teeth were randomly distributed into four different groups: Three-step etch-and-rinse (Adper Scotchbond Multi-Purpose, 3M ESPE - SBMP, two-step etch-and-rinse (Adper Single Bond 2, 3 M ESPE - SB; two-step self-etch (AdheSE, Ivoclar/Vivadent - AD; and self-etch 1 step (Adper Prompt L-Pop, 3M ESPE - LP. Following the adhesive application (n = 6, resin composite was incrementally applied (Filtek™ Supreme XT - 3 M ESPE in order to obtain bonded sticks, with a cross-sectioned area of 0.81 mm 2 . The bonded sticks were randomly divided and assigned to be tested after one day [OD] (n 30 or six months [6 M] of water storage [6 M] (n = 30. Results: Two-way ANOVA and Tukey′s test showed that none of the adhesives showed degradation after 6 M. SB achieved the highest µTBS both in the [OD] (49.13 MPa and [6M] (40.27 MPa. Despite the highest values in both time evaluations, the µTBS of SB significantly reduced after 6M. LP showed the lowest µTBS in both periods of evaluation (18.35 and 18.34 MPa. Conclusions: Although a significant degradation was only observed for SB, this was the adhesive that showed the highest µTBS after 6 M of water storage.

  6. Isolation of a Pseudomonas aeruginosa strain from soil that can degrade polyurethane diol.

    Science.gov (United States)

    Mukherjee, Koushik; Tribedi, Prosun; Chowdhury, Arup; Ray, Tanusree; Joardar, Archi; Giri, Subhajit; Sil, Alok Kumar

    2011-04-01

    Polyurethane diol (PUR-diol), a synthetic polymer, is widely used as a modifier for water-soluble resins and emulsions in wood appliances and auto coatings. Non-biodegradability of polyurethanes (PUR) and PUR-based materials poses a threat to environment that has led scientists to isolate microbes capable of degrading PUR. However, the bio-degradation of PUR-diol has not yet been reported. In this study, we report isolation of a soil bacterium that can survive using PUR-diol as sole carbon source. PUR-diol degradation by the organism was confirmed by thin layer chromatographic analysis of the conditioned medium obtained after the growth wherein a significant reduction of PUR-diol was observed compared to non-inoculated medium. To quantify the PUR-diol degradation, a sensitive assay based on High Performance Thin Layer Chromatography has been developed that showed 32% degradation of PUR-diol by the organism in 10 days. Degradation kinetics showed the maximal depletion of PUR-diol during logarithmic growth of the organism indicating a direct relation between the growth and PUR-diol degradation. Mutagenic study and GC-MS analysis revealed that esterase activity is involved in this degradation event. The ribotyping and metabolic fingerprinting analysis showed that this organism is a strain of Pseudomonous aeruginosa (P. aeruginosa). It has also been observed that this strain is able to degrade Impranil DLN™, a variety of commercially available PUR. Therefore this study identifies a new bacterium from soil that has the potential to reduce PUR-related waste burden and adds a new facet to diverse functional activities of P. aeruginosa.

  7. Influence of coffee on reflectance and chemistry of resin composite protected by surface sealant.

    Science.gov (United States)

    Soares, Luís Eduardo Silva; Cesar, Ilene Cristine Rosia; Santos, Carla Gabriela Couto; De Cardoso, Ana Luiza Merigo Oliveira; Liporoni, Priscila Christiane Suzy; Munin, Egberto; Martin, Airton Abrahão

    2007-10-01

    To assess the influence of the light-curing unit type and whether or not it was worth using surface sealant protection on resin composite restorative materials stained by coffee. Another objective was to propose the monitoring of coffee staining by FT-Raman spectroscopy using carbon-hydrogen (C-H) bonds as reference to the composite matrix degradation. Sixty cylindrical specimens of resin composite were prepared and divided into six groups: HC (control)--cured with a halogen light; LC (control) cured with a LED; HF--cured with a halogen light + Fortify Plus; LF--cured with a LED + Fortify Plus; HP--cured with a halogen light + PermaSeal; LP--cured with a LED + PermaSeal. After storage for 24 hours at 37% and 100% of relative humidity, the top surface was protected, and the other surfaces isolated. Polishing with paper discs was performed after 24 hours of curing and prior to FT-Raman spectroscopy and reflectance measurements. All specimens were submitted to coffee staining for 14 days and evaluated by both systems. Results were statistically analyzed by ANOVA and Tukey tests. FT-Raman spectrum only showed significant changes in groups LC and LP (P< 0.05). Reflectance demonstrated that staining was present in all specimens protected by sealants. Sealant staining was larger in the HF (P < 0.001) group.

  8. PLGA nanoparticles as chlorhexidine-delivery carrier to resin-dentin adhesive interface.

    Science.gov (United States)

    Priyadarshini, Balasankar Meera; Mitali, Kakran; Lu, Thong Beng; Handral, Harish K; Dubey, Nileshkumar; Fawzy, Amr S

    2017-07-01

    To characterize and deliver fabricated CHX-loaded PLGA-nanoparticles inside micron-sized dentinal-tubules of demineralized dentin-substrates and resin-dentin interface. Nanoparticles fabricated by emulsion evaporation were assessed in-vitro by different techniques. Delivery of drug-loaded nanoparticles to demineralized dentin substrates, interaction with collagen matrix, and ex-vivo CHX-release profiles using extracted teeth connected to experimental setup simulating pulpal hydrostatic pressure were investigated. Furthermore, nanoparticles association/interaction with a commercial dentin-adhesive applied to demineralized dentin substrates were examined. The results showed that the formulated nanoparticles demonstrated attractive physicochemical properties, low cytotoxicity, potent antibacterial efficacy, and slow degradation and gradual CHX release profiles. Nanoparticles delivered efficiently inside dentinal-tubules structure to sufficient depth (>10μm) against the simulated upward pulpal hydrostatic-pressure, even after bonding-resins infiltration and were attached/retained on collagen-fibrils. These results verified the potential significance of this newly introduced drug-delivery therapeutic strategy for future clinical applications and promote for a new era of future dental research. This innovative drug-delivery strategy has proven to be a reliable method for delivering treatments that could be elaborated for other clinical applications in adhesive and restorative dentistry. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. Saturated Resin Ectopic Regeneration by Non-Thermal Dielectric Barrier Discharge Plasma

    Directory of Open Access Journals (Sweden)

    Chunjing Hao

    2017-11-01

    Full Text Available Textile dyes are some of the most refractory organic compounds in the environment due to their complex and various structure. An integrated resin adsorption/Dielectric Barrier Discharge (DBD plasma regeneration was proposed to treat the indigo carmine solution. It is the first time to report ectopic regeneration of the saturated resins by non-thermal Dielectric Barrier Discharge. The adsorption/desorption efficiency, surface functional groups, structural properties, regeneration efficiency, and the intermediate products between gas and liquid phase before and after treatment were investigated. The results showed that DBD plasma could maintain the efficient adsorption performance of resins while degrading the indigo carmine adsorbed by resins. The degradation rate of indigo carmine reached 88% and the regeneration efficiency (RE can be maintained above 85% after multi-successive regeneration cycles. The indigo carmine contaminants were decomposed by a variety of reactive radicals leading to fracture of exocyclic C=C bond, which could cause decoloration of dye solution. Based on above results, a possible degradation pathway for the indigo carmine by resin adsorption/DBD plasma treatment was proposed.

  10. Hardening of a dual-cure resin cement using QTH and LED curing units

    Science.gov (United States)

    SANTOS, Maria Jacinta Moraes Coelho; PASSOS, Sheila Pestana; da ENCARNAÇÃO, Monalisa Olga Lessa; SANTOS, Gildo Coelho; BOTTINO, Marco Antonio

    2010-01-01

    Objective This study evaluated the surface hardness of a resin cement (RelyX ARC) photoactivated through indirect composite resin (Cristobal) disks of different thicknesses using either a light-emitting diode (LED) or quartz tungsten halogen (QTH) light source. Material and Methods Eighteen resin cement specimens were prepared and divided into 6 groups according to the type of curing unit and the thickness of resin disks interposed between the cement surface and light source. Three indentations (50 g for 15 s) were performed on the top and bottom surface of each specimen and a mean Vickers hardness number (VHN) was calculated for each specimen. The data were analyzed using two-way ANOVA and Tukey-Kramer test was used for post-hoc pairwise comparisons. Results Increased indirect resin disk thickness resulted in decreased mean VHN values. Mean VHN values for the top surfaces of the resin cement specimens ranged from 23.2 to 46.1 (QTH) and 32.3 to 41.7 (LED). The LED curing light source produced higher hardness values compared to the QTH light source for 2- and 3-mm-thick indirect resin disks. The differences were clinically, but not statistically significant. Increased indirect resin disk thickness also resulted in decreased mean VHN values for the bottom surfaces of the resin cement: 5.8 to 19.1 (QTH) and 7.5 to 32.0 (LED). For the bottom surfaces, a statistically significant interaction was also found between the type of curing light source and the indirect resin disk thickness. Conclusions Mean surface hardness values of resin cement specimens decreased with the increase of indirect resin disk thickness. The LED curing light source generally produced higher surface hardness values. PMID:20485920

  11. Hardening of a dual-cure resin cement using QTH and LED curing units

    Directory of Open Access Journals (Sweden)

    Maria Jacinta Moraes Coelho Santos

    2010-04-01

    Full Text Available OBJECTIVE: This study evaluated the surface hardness of a resin cement (RelyX ARC photoactivated through indirect composite resin (Cristobal disks of different thicknesses using either a light-emitting diode (LED or quartz tungsten halogen (QTH light source. MATERIAL AND METHODS: Eighteen resin cement specimens were prepared and divided into 6 groups according to the type of curing unit and the thickness of resin disks interposed between the cement surface and light source. Three indentations (50 g for 15 s were performed on the top and bottom surface of each specimen and a mean Vickers hardness number (VHN was calculated for each specimen. The data were analyzed using two-way ANOVA and Tukey-Kramer test was used for post-hoc pairwise comparisons. RESULTS: Increased indirect resin disk thickness resulted in decreased mean VHN values. Mean VHN values for the top surfaces of the resin cement specimens ranged from 23.2 to 46.1 (QTH and 32.3 to 41.7 (LED. The LED curing light source produced higher hardness values compared to the QTH light source for 2- and 3-mm-thick indirect resin disks. The differences were clinically, but not statistically significant. Increased indirect resin disk thickness also resulted in decreased mean VHN values for the bottom surfaces of the resin cement: 5.8 to 19.1 (QTH and 7.5 to 32.0 (LED. For the bottom surfaces, a statistically significant interaction was also found between the type of curing light source and the indirect resin disk thickness. CONCLUSION: Mean surface hardness values of resin cement specimens decreased with the increase of indirect resin disk thickness. The LED curing light source generally produced higher surface hardness values.

  12. Optimizing dentin bond durability: strategies to prevent hydrolytic degradation of the hybrid layer

    Science.gov (United States)

    Tjäderhane, Leo; Nascimento, Fabio D.; Breschi, Lorenzo; Mazzoni, Annalisa; Tersariol, Ivarne L.S.; Geraldeli, Saulo; Tezvergil-Mutluay, Arzu; Carrilho, Marcela; Carvalho, Ricardo M.; Tay, Franklin R.; Pashley, David H.

    2014-01-01

    Objectives Endogenous dentin collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, are responsible for the time-related hydrolysis of collagen matrix of the hybrid layers. As the integrity of the collagen matrix is essential for the preservation of long-term dentin bond strength, inhibition or inactivation of endogenous dentin proteases is necessary for durable resin-bonded composite resin restorations. Methods Dentin contains collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, which are responsible for the hydrolytic degradation of collagen matrix in the bonded interface. Several tentative approaches to prevent enzyme function either directly or indirectly have been proposed in the literature. Results Chlorhexidine, a general inhibitor of both MMPs and cysteine cathepsins, applied before primer/adhesive application is the most tested method. In general, these experiments have shown that enzyme inhibition is a promising scheme to improve hybrid layer preservation and bond strength durability. Other enzyme inhibitors, e.g. enzyme-inhibiting monomers and antimicrobial compounds, may be considered promising alternatives that would allow more simple clinical application than chlorhexidine. Cross-linking collagen and/or dentin organic matrix-bound enzymes could render hybrid layer organic matrix resistant to degradation, and complete removal of water from the hybrid layer with ethanol wet bonding or biomimetic remineralization should eliminate hydrolysis of both collagen and resin components. Significance Identification of the enzymes responsible for the hydrolysis of hybrid layer collagen and understanding their function has prompted several innovative approaches to retain the hybrid layer integrity and strong dentin bonding. The ultimate goal, prevention of collagen matrix degradation with techniques and commercially available materials that are simple and effective in clinical settings may be achievable in

  13. Effects of Hygrothermal Cycling on the Chemical, Thermal, and Mechanical Properties of 862/W Epoxy Resin

    Science.gov (United States)

    Miller, Sandi G.; Roberts, Gary D.; Copa, Christine C.; Bail, Justin L.; Kohlman, Lee W.; Binienda, Wieslaw K.

    2011-01-01

    The hygrothermal aging characteristics of an epoxy resin were characterized over 1 year, which included 908 temperature and humidity cycles. The epoxy resin quickly showed evidence of aging through color change and increased brittleness. The influence of aging on the material s glass transition temperature (Tg) was evaluated by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). The Tg remained relatively constant throughout the year long cyclic aging profile. The chemical composition was monitored by Fourier Transform Infrared Spectroscopy (FTIR) where evidence of chemical aging and advancement of cure was noted. The tensile strength of the resin was tested as it aged. This property was severely affected by the aging process in the form of reduced ductility and embrittlement. Detailed chemical evaluation suggests many aging mechanisms are taking place during exposure to hygrothermal conditions. This paper details the influence of processes such as: advancement of cure, chemical degradation, and physical aging on the chemical and physical properties of the epoxy resin.

  14. The study of radiation effect on 127-epoxy resin adhesive and its components

    International Nuclear Information System (INIS)

    Zhong Zhijing; Luo Shikai; Fu Yibei; Luo Shunzhong

    2001-01-01

    127-epoxy resin adhesive and its components: E-44 epoxy resin, dibutyl-o-phthalate and anhydrous ethylenediamine were irradiated with γ ray in air, nitrogen or vacuum at ambient temperature respectively. The gaseous products such as hydrogen, methane and carbon dioxide were examined by means of GC. Remarkable effect of ambiences and dose on γ radiated degradation of these specimen were found. The results indicated that the content of gaseous products increased with dose, but changed with ambiences. The forming of carbon dioxide was not only determined by the amount of oxygen in ambience, but also by whether the specimens structure contained oxygenous groups or not. It was shown that there were good linear increasing relationships between dose and the concentration of gaseous products hydrogen and methane for 127-epoxy resin adhesive, and methane for dibutyl-o-phthalate. All above indicated low radiation-resistance of 127-epoxy resin adhesive

  15. Alkyd-amino resins based on waste PET for coating applications

    International Nuclear Information System (INIS)

    Torlakoglu, A.; Gueclue, G.

    2009-01-01

    Waste polyethylene terephthalate (PET) flakes were depolymerized by using propylene glycol (PG) in the presence of zinc acetate as catalyst. Glycolysis reaction products of waste PET obtained by using PET/glycol molar ratio 1/2. Two short oil alkyd resins of high acid values (30-40 mgKOH/g) were prepared from phthalic anhydride (PA), glycerin (G), coconut oil fatty acids (COFA) and glycolyzed products of waste PET (PET-based alkyd resins) or glycols (PG) (reference alkyd resins). These alkyd resins were blended with 30%, 40%, and 50% of a commercial urea-formaldehyde, melamine-formaldehyde and urea-formaldehyde/melamine-formaldehyde mixture (1/1 weight ratio) and heated at 140 deg. C. The physical and chemical properties such as drying time, hardness, abrasion resistance, adhesion strength, water resistance, alkaline resistance, acid resistance, gelation time, and thermal oxidative degradation resistance (with thermogravimetric analysis, TGA) of these alkyd-amino resins were investigated. The properties of the waste PET-based resins were found to be compatible with the properties of the reference resins

  16. Alkyd-amino resins based on waste PET for coating applications.

    Science.gov (United States)

    Torlakoğlu, A; Güçlü, G

    2009-01-01

    Waste polyethylene terephthalate (PET) flakes were depolymerized by using propylene glycol (PG) in the presence of zinc acetate as catalyst. Glycolysis reaction products of waste PET obtained by using PET/glycol molar ratio 1/2. Two short oil alkyd resins of high acid values (30-40mgKOH/g) were prepared from phthalic anhydride (PA), glycerin (G), coconut oil fatty acids (COFA) and glycolyzed products of waste PET (PET-based alkyd resins) or glycols (PG) (reference alkyd resins). These alkyd resins were blended with 30%, 40%, and 50% of a commercial urea-formaldehyde, melamine-formaldehyde and urea-formaldehyde/melamine-formaldehyde mixture (1/1 weight ratio) and heated at 140 degrees C. The physical and chemical properties such as drying time, hardness, abrasion resistance, adhesion strength, water resistance, alkaline resistance, acid resistance, gelation time, and thermal oxidative degradation resistance (with thermogravimetric analysis, TGA) of these alkyd-amino resins were investigated. The properties of the waste PET-based resins were found to be compatible with the properties of the reference resins.

  17. Characterization and disposal of ion exchange resins used in nuclear installations

    International Nuclear Information System (INIS)

    Flores E, R.M.; Ortiz O, H.B.; Olguin G, M.T.; Emeterio H, M.; Garcia M, H.

    2006-01-01

    To dispose of an appropriate way the used ion exchange resins so much in the pool water purification systems of the TRIGA Mark III reactor like in the JS6500 gamma irradiator, of the National Institute of Nuclear Research, were carried out a series of analytic nuclear techniques and complementary conventional to those recommended by the ASTM, with the object of to control and to manage 14 lots of worn out resins appropriately. For its were identified the radioactive isotopes, the resins type, the grade of chemical pollution and the physicochemical degradation of the same ones. The lots of resins that didn't contain radioactive isotopes its were regenerated in an usual way, as long as those that if they controlled them they selected options for its final disposition. The first selected option was the extraction method of ion radioactive isotopes, concentrating the elution product by evaporation. As second option it was carried out the resins stabilization damaged by micro-encapsulation by forged to ambient temperature, using an organic polymer. Previous to the immobilization the resins were pretreated by vacuum drying, pulverization and thermal drying, however before carrying out this last, it was carried out a thermal gravimetric analysis to determine the drying conditions of the resins avoiding its chemical decomposition. (Author)

  18. A comparison of the fitting accuracy of thermoplastic denture base resins used in non-metal clasp dentures to a conventional heat-cured acrylic resin.

    Science.gov (United States)

    Wada, Junichiro; Fueki, Kenji; Yatabe, Masaru; Takahashi, Hidekazu; Wakabayashi, Noriyuki

    2015-01-01

    To incorporate a metal framework into removable partial dentures, the dimensional accuracy of thermoplastic resins requires precision equivalent to conventional acrylic resins. This study aimed to evaluate the fitting accuracy of thermoplastic resins compared to heat-cured acrylic resin. Four thermoplastic resins (polyethylene terephthalate [EstheShot, ES; EstheShot Bright, ES-B], polyamide [Lucitone FRS, LF], polycarbonate [Reigning Resin N, RN] and a heat-curing acrylic resin [Acron, AC]) were used. The specimens were created on master casts constructed of high-strength stone that simulated a maxillary edentulous ridge. Additionally, high-expansion stone was used as the master cast for RN specimens. The ES-B, LF and RN specimens were prepared with and without annealing after injection molding. The gaps between the molded resin and the cast were measured. ES had the smallest gap and was significantly smaller than AC (p 0.05), while the gap size of RN (high-strength stone) with and without annealing was significantly greater than AC (p dentures and that annealing effectively improved the fitting accuracy of ES-B, LF and RN.

  19. Relative biocompatibility of micro-hybrid and nano-hybrid light-activated composite resins.

    Science.gov (United States)

    Olabisi Arigbede, Abiodun; Folasade Adeyemi, Bukola; Femi-Akinlosotu, Omowumi

    2017-01-01

    Background. In vitro studies have revealed a direct association between resin content and cytotoxicity of composite resins; however, implantation studies in this regard are sparse. This study investigates the relationship between filler content of composite resins and biocompatibility. Methods. This research employed twelve 180‒200-gr male Wistar rats, 1 nano-hybrid (Prime-Dent Inc.) and 1 micro-hybrid (Medental Inc.) composite resins containing 74% and 80‒90% filler content, respectively. The samples were assessed on the 2nd, 14th and 90th day of implantation. Four rats were allocated to each day in this experimental study. A section of 1.5mm long cured nano-hybrid and micro-hybrid materials were implanted into the right and left upper and lower limbs of the rats, respectively. Eight samples were generated on each day of observation. Inflammation was graded according to the criteria suggested by Orstavik and Major. Pearson's chi-squared test was employed to determine the relationship between the tissue responses of the two materials. Statistical significance was set at P resin had a score of 3.0 for cellular inflammation. On the 14th day, the micro-hybrid resin also exhibited a lower average grade for cellular inflammation. On the 90th day, the micro-hybrid resin had a higher grade of inflammation (0.9) compared to 0.3 recorded for nano-hybrid. The composite resins with higher filler content elicited a significantly lower grade of inflammation irrespective of the duration (χ=20.000, df=8, P=0.010) while the composite resins with lower filler content elicited a significantly lower inflammatory response on the 90th day (χ=4.000, df=1, P=0.046). Conclusion. The composite resins with higher filler content generally elicited significantly lower grades of inflammation, and the composite resins with lower filler content exhibited significantly lower inflammatory response on the 90th day of implantation.

  20. Wear resistance of injection-molded thermoplastic denture base resins

    Science.gov (United States)

    Hamanaka, Ippei; Iwamoto, Misa; Lassila, Lippo V. J.; Vallittu, Pekka K.; Takahashi, Yutaka

    2016-01-01

    Abstract Objective This study investigated the wear resistance of injection-molded thermoplastic denture base resins using nanoindentation instrument. Materials and methods Six injection-molded thermoplastic denture base resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate [PMMA]) and a PMMA conventional heat-polymerized denture-based polymer control were tested. Elastic modulus, hardness, wear depth, and roughness were calculated using a nanoindentation instrument. Results Elastic modulus and hardness of the injection-molded thermoplastic denture base resins were significantly lower than those of the PMMA conventional heat-polymerized denture-based polymer. Wear depth of polycarbonate and PMMA conventional heat-polymerized denture-based polymer were significantly higher than that of other injection-molded thermoplastic denture base resins. The roughness of injection-molded thermoplastic denture base resins was significantly more than that of PMMA conventional heat-polymerized denture-based polymer after testing. Conclusions Wear resistance of injection-molded thermoplastic denture base was low compared to PMMA conventional heat-polymerized denture-based polymers. PMID:28642909

  1. Ion exchange resins destruction in a stirred supercritical water oxidation reactor

    International Nuclear Information System (INIS)

    Leybros, A.; Roubaud, A.; Guichardon, P.; Boutin, O.

    2010-01-01

    Spent ion exchange resins (IERs) are radioactive process wastes for which there is no satisfactory industrial treatment. Supercritical water oxidation offers a viable treatment alternative to destroy the organic structure of resins, used to remove radioactivity. Up to now, studies carried out in supercritical water for IER destruction showed that degradation rates higher than 99% are difficult to obtain even using a catalyst or a large oxidant excess. In this study, a co-fuel, isopropanol, has been used in order to improve degradation rates by initiating the oxidation reaction and increasing temperature of the reaction medium. Concentrations up to 20 wt% were tested for anionic and cationic resins. Total organic carbon reduction rates higher than 99% were obtained from this process, without the use of a catalyst. The influence of operating parameters such as IERs feed concentration, nature and counterions of exchanged IERs were also studied. (authors)

  2. Cathode degradation

    Energy Technology Data Exchange (ETDEWEB)

    Shores, D.A.; Selman, J.R.; Ong, E.T.

    1989-12-01

    This report describes the results of a three-year study of cathode degradation in molten carbonate fuel cells involving both experimental and theoretical work. A keystone of the study is the development of a mathematical model, which describes cathode degradation in terms of the fundamental processes of a fluxing mechanism, i.e., dissolution, transport and precipitation. New fundamental data have been obtained on the solubility of NiO, especially on the effect of water vapor, and on the kinetics of NiO dissolution in (Li{sub 0.62}K{sub 0.38}){sub 2}CO{sub 3}, and these data have been incorporated in the model. Laboratory cell testing in 3 cm{sup 2} cells has been carried out to obtain experimental data on degradation rates for direct comparison with the calculated results from the model. These comparisons have helped to verify several aspects of the model. For example, the model predicts with fair accuracy the location of the Ni deposit in the tile and the deposition rate. It is also fair to point out that the model is a relatively simple representation of complex processes, and it does not answer all questions about cathode degradation. Further work is needed. Because of its fundamental basis, the model can readily be upgraded and extended when further experimental data become available. The solubility studies, modeling efforts and cell testing have interacted iteratively to optimize progress. 94 figs., 24 tabs.

  3. Dynamic Mechanical Properties and Thermal Effect of an Epoxy Resin Composite, Encapsulation's Element of a New Electronic Component

    Science.gov (United States)

    Rmili, W.; Deffarges, M. P.; Chalon, F.; Ma, Z.; Leroy, R.

    2013-11-01

    Epoxy resin is used in many industrial applications principally in the microelectronic field to protect integrated circuits. However, these components are subject to various environments such as moisture and thermal fluctuations during packaging. Consequently, mechanical, physical and chemical properties of the resin can be affected. For an epoxy resin composite designed for a future application, an evaluation of the relevant properties was carried out using a dynamic mechanical analyzer and a thermogravimetric analysis (TGA) instrument. The surface morphology was investigated using scanning electron microscopy to examine the impact of post-cured treatment through evolution of the rigidity and of the glass transition temperature. Subsequently, a temperature classification was proposed to define the temperature limit for safe use of the material. Finally, temperature degradation was observed and confirmed by TGA tests. Results from all of these analyses bring understanding to the phenomenon of thermal degradation and its influence on the stability of the epoxy resin composite.

  4. Characterization of phenolic resins with thermogravimetry-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Cherng; Tackett, J.R.

    1990-01-01

    As part of an advanced material research program, thermogravimetry-mass spectrometry (TG-MS) analysis of a phenolic resin was carried out recently for the study of the curing of the prepolymer, solvent extraction, and carbonization of the polymer at high temperature in inert atmosphere. These steps are critical to the quality of the produced advanced material. In addition to TG-MS, several other complementary techniques were also employed for the analysis of the phenolic resin prepolymer and its curing and thermal degradation products. These techniques include pyrolysis-gas chromatography-mass spectrometry, direct insertion probe-mass spectrometry and gas chromatography-mass spectrometry. 7 refs., 5 figs., 3 tabs.

  5. The comparison of naturally weathered oil and artificially photo-degraded oil at the molecular level by a combination of SARA fractionation and FT-ICR MS

    International Nuclear Information System (INIS)

    Islam, Ananna; Cho, Yunju; Yim, Un Hyuk; Shim, Won Joon; Kim, Young Hwan; Kim, Sunghwan

    2013-01-01

    Highlights: • Weathered oils from the Hebei Spirit oil spill and photo degraded oils are compared. • We investigate changes of polar species at the molecular level by 15T FT-ICR MS. • Significant reduction of sulfur class compounds in saturates fraction is observed. • The relative abundance of protonated compounds (presumably basic nitrogen compounds) increase after degradation. • Changes of polar compounds occurred by natural and photo degradation are similar. -- Abstract: Two sets of oil samples, one obtained from different weathering stages of the M/V Hebei Spirit oil spill site and the other prepared by an in vitro photo-degradation experiment, were analyzed and compared at the molecular level by atmospheric pressure photo-ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). For a more detailed comparison at the molecular level, the oil samples were separated into saturate, aromatic, resin, and asphaltene (SARA) fractions before MS analysis. Gravimetric analysis of the SARA fractions revealed a decreased weight percentage of the aromatic fraction and an increased resin fraction in both sets of samples. Molecular-level investigations of the SARA fractions showed a significant reduction in the S 1 class in the saturate fraction and increase of S 1 O 1 class compounds with high DBE values in resin fraction. Levels of N 1 and N 1 O 1 class compounds resulting in protonated ions (presumably basic nitrogen compounds) increased after degradation compared to compounds generating molecular ions (presumably non-basic nitrogen compounds). This study revealed changes occurring in heteroatom polar species of crude oils such as sulfur and nitrogen containing compounds that have not been easily detected with conventional GC based techniques

  6. Effect of 180 days of water storage on the transverse strength of acetal resin denture base material.

    Science.gov (United States)

    Arikan, Ayla; Ozkan, Yasemin Kulak; Arda, Tugberk; Akalin, Buket

    2010-01-01

    Acetal resin has been used as an alternative denture base and clasp material since 1986. The manufacturers claim that acetal resin has superior physical properties when compared to conventional denture base acrylic resins. Limited information is available about transverse strengths of acetal resin. The purpose of this investigation was to compare transverse strengths of pink and white acetal resins to transverse strengths of conventional heat-polymerized polymethylmethacrylate (PMMA) resin in increasing durations of water storage. A transverse strength test was performed in accordance with International Standards Organization (ISO) specification No 1567. Twenty 65 x 10 x 2.5 mm(3) specimens of each resin were prepared; five specimens of each resin group were subjected to three-point bending test after 50 hours, 30 days, 60 days, and 180 days of water storage in distilled water at 37 degrees C. Experimental groups' transverse strengths were compared by three-way ANOVA and Duncan's multiple range tests. Transverse strength of PMMA denture base material was found to be in accordance with the requirements of ISO specification No 1567. Transverse strengths of white and pink acetal resin could not be calculated in this study, as white and pink acetal resin specimens did not break at the maximum applied force in the three-point bending test. Flexural strength of acetal resin was found to be within the ISO specification limits. As the water storage time increased, the deflection values of PMMA showed no significant difference (p > 0.05). Both the white and pink acetal resin showed significant increase in deflection as the water storage time was increased from 50 hours to 180 days (p resin suffered from permanent deformation, but did not break in the three-point bending test. Acetal resin showed significant increase in deflection as the water storage time was increased from 50 hours to 180 days. All materials tested demonstrated deflection values in compliance with ISO

  7. Fatigue resistance and failure mode of adhesively restored custom metal-composite resin premolar implant abutments.

    Science.gov (United States)

    Boff, Luís Leonildo; Oderich, Elisa; Cardoso, Antônio Carlos; Magne, Pascal

    2014-01-01

    To evaluate the fatigue resistance and failure mode of composite resin and porcelain onlays and crowns bonded to premolar custom metal-composite resin premolar implant abutments. Sixty composite resin mesostructures were fabricated with computer assistance with two preparation designs (crown vs onlay) and bonded to a metal implant abutment. Following insertion into an implant with a tapered abutment interface (Titamax CM), each metal-composite resin abutment was restored with either composite resin (Paradigm MZ100) or ceramic (Paradigm C) (n = 15) and attached with adhesive resin (Optibond FL) and a preheated light-curing composite resin (Filtek Z100). Cyclic isometric chewing (5 Hz) was then simulated, starting with 5,000 cycles at a load of 50 N, followed by stages of 200, 400, 600, 800, 1,000, 1,200, and 1,400 N (25,000 cycles each). Samples were loaded until fracture or to a maximum of 180,000 cycles. The four groups were compared using life table survival analysis (log-rank test). Previously published data using zirconia abutments of the same design were included for comparison. Paradigm C and MZ100 specimens fractured at average loads of 1,133 N and 1,266 N, respectively. Survival rates ranged from 20% to 33.3% (ceramic crowns and onlays) to 60% (composite resin crowns and onlays) and were significantly different (pooled data for restorative material). There were no restoration failures, but there were adhesive failures at the connection between the abutment and the mesostructure. The survival of the metal-composite resin premolar abutments was inferior to that of identical zirconia abutments from a previous study (pooled data for abutment material). Composite resin onlays/crowns bonded to metal-composite resin premolar implant abutments presented higher survival rates than comparable ceramic onlays/crowns. Zirconia abutments outperformed the metal-composite resin premolar abutments.

  8. Resin technologies: construction and staining of resin TMA's.

    Science.gov (United States)

    Howat, William J; Wilson, Susan J

    2010-01-01

    The traditional formaldehyde-fixed paraffin-embedded tissue, and therefore the tissue microarrays created from it, provide good morphology but with a compromised antigenicity when compared to frozen tissue. In contrast, while solving the issue of antigenicity, frozen tissue suffers from a lack of morphology. We have demonstrated that tissue microarrays constructed in glycol methacrylate resin, when combined with a cold acetone fixation step, have been able to combine the superior morphology of resin-embedded sections with the superior antigenicity of frozen tissue for prospectively collected material.

  9. Strain Rate Sensitivity of Epoxy Resin in Tensile and Shear Loading

    Science.gov (United States)

    Gilat, Amos; Goldberg, Robert K.; Roberts, Gary D.

    2005-01-01

    The mechanical response of E-862 and PR-520 resins is investigated in tensile and shear loadings. At both types of loading the resins are tested at strain rates of about 5x10(exp 5), 2, and 450 to 700 /s. In addition, dynamic shear modulus tests are carried out at various frequencies and temperatures, and tensile stress relaxation tests are conducted at room temperature. The results show that the toughened PR-520 resin can carry higher stresses than the untoughened E-862 resin. Strain rate has a significant effect on the response of both resins. In shear both resins show a ductile response with maximum stress that is increasing with strain rate. In tension a ductile response is observed at low strain rate (approx. 5x10(exp 5) /s), and brittle response is observed at the medium and high strain rates (2, and 700 /s). The hydrostatic component of the stress in the tensile tests causes premature failure in the E-862 resin. Localized deformation develops in the PR-520 resin when loaded in shear. An internal state variable constitutive model is proposed for modeling the response of the resins. The model includes a state variable that accounts for the effect of the hydrostatic component of the stress on the deformation.

  10. In Vitro Color Change of Three Dental Veneering Resins in Tea, Coffee and Tamarind Extracts

    Directory of Open Access Journals (Sweden)

    S. Muttagi

    2011-09-01

    Full Text Available Objective: To study the in vitro color changes of three dental resin veneering materials when immersed in tea, coffee and tamarind extracts.Materials and Methods: The color changes of heat polymerized tooth colored acrylic resin (Stellondetrey, B, F14, DPI Dental products of India Ltd, Mumbai, auto polymerized tooth colored acrylic resin (DPI, B, QV5, DPI Dental products of India Ltd, Mumbai andlight polymerized resin composite (Herculite XRV, Enamel A2, part no. 22860, lot no. 910437, Kerr Corporation, West Collins Avenue, Orange, CA, USA when immersed in water extracts of tea (Tata Tea Ltd. Bangalore, India, coffee (Tata Coffee Ltd. Coorg, Indiaand tamarind were evaluated using computer vision systems. The color images were recorded in R (red, G (green and B (blue form and converted into H (hue, S (saturationand V (value.Results: Significant color change occurred for auto polymerized tooth colored acrylic resin in tamarind extract, for heat polymerized tooth colored acrylic resin in tea extract andfor light polymerized resin composite in coffee extract. Auto polymerized tooth colored acrylic resin samples showed an overall higher color change. However, for all the material samples coffee extract produced more color change.Conclusion: These results suggest that the color stability of the resins is influenced by the presence of secondary metabolites such as tartaric acid, tannins, caffeine, saponins and phenols in tamarind, tea and coffee extracts.

  11. Flexural Strength of Cold and Heat Cure Acrylic Resins Reinforced with Different Materials.

    Science.gov (United States)

    Heidari, Bijan; Firouz, Farnaz; Izadi, Alireza; Ahmadvand, Shahbaz; Radan, Pegah

    2015-05-01

    Heat-polymerized acrylic resin has been the most commonly used denture base material for over 60 years. However, the mechanical strength of acrylic resin is not adequate for long-term clinical performance of dentures. Consequently, fracture is a common clinical occurrence, which often develops in the midline of the denture base. This study aimed to evaluate the efficacy of cold-cure and heat-cure acrylic resins, reinforced with glass fibers, polyethylene fibers, and metal wire for denture base repair. Ninety specimens were prepared and allocated to nine groups. Ten specimens were considered as controls, and 80 were divided into 8 experimental groups. In the experimental groups, the specimens were sectioned into two halves from the middle, and were then divided into two main groups: one group was repaired with heat cure acrylic resin, and the other with cold cure acrylic resin. Each group was divided into 4 subgroups: unreinforced, reinforced with glass fibers, polyethylene fibers, and metal wire. All specimens were subjected to a 3-point bending test, and the flexural strength was calculated. The group repaired with heat cure acrylic resin and reinforced with glass fiber showed the highest flexural strength; however, the group repaired with cold cure acrylic resin and reinforced with polyethylene fibers had the lowest flexural strength. There was no significant difference between the groups repaired with heat cure and cold cure acrylic resins without reinforcement. Repairing denture base with heat cure acrylic resin, reinforced with glass fibers increases the flexural strength of denture base.

  12. Behavior study of spend ion exchange resins immobilized in pyrolyzed polymer matrix

    International Nuclear Information System (INIS)

    Ramos, P.B; Fuentes, N.O; Luca, V.

    2012-01-01

    The pyrolysis of spent ion exchange resins contained in epoxy resins represents an attractive alternative to cementation as a confining method. In this sense, a significant reduction of volume can be achieved, as well as avoiding the dispersion of the exhausted ion exchange resin by the means of an epoxy resin used as a matrix, while potentially limiting the release of highly radioactive long life isotopes such us Cs-137, Sr-90 and Co-60 among others. Three types of monoliths were made: (i) epoxy resin, (ii) epoxy resin with carbon and (iii) a binder of epoxy resin and clay. In every case, the monolith contained the ion exchange resin. They were prepared by the mixing of resin pearl loaded with epoxy cations and a subsequent pyrolysis process with a temperature increase ratio of 2 o C /min reaching maximum values in the range between 200 o C - 800 o C, remaining in it for 1 hour. Monoliths obtained for each final temperature had been characterized to obtain data corresponding to the mass loss, volume reduction and lixiviation, as well as mechanical and microstructural properties (author)

  13. Effect of LED light-curing time for the adhesive resin on the modulus of elasticity.

    Science.gov (United States)

    Senawongse, Pisol; Harnirattisai, Choltacha; Otsuki, Masayuki; Tagami, Junji

    2007-06-01

    To evaluate the elastic modulus of successive layers where an adhesive resin was cured by different light-curing times. Eighty dentin discs which were 2 mm thick were prepared from 40 sound third molars. The dentin discs were further divided into four groups and bonded with 3M Single Bond 2 and cured with an LED for 5, 10, 15 and 20s. Bonded specimens were restored with a microhybrid resin composite. Specimens were cut perpendicular to the resin dentin interface, embedded in epoxy resin, and polished. Polished specimens were evaluated for the elastic modulus at the layer of dentin, hybrid layer, adhesive resin, and resin composite at 24 hours after preparation. Light-curing times influenced the elastic modulus of hybrid layer and adhesive resin. The significant differences of elastic modulus among successive layers were found. The results suggested that extension of light-curing times of adhesive resin from 5 to 20 seconds increased the mechanical properties of the resin dentin interface.

  14. Surface roughness comparison of methacrylate and silorane-based composite resins after 40% hydrogen peroxide application

    Directory of Open Access Journals (Sweden)

    Rori Sasmita

    2018-01-01

    Full Text Available The change of the tooth colour could be restored with bleaching. The tooth bleaching will affects the surface roughness of the composite resins. Recently, the material basis for composite resins has developed, among others are methacrylate-based and silorane based composite resins. The objective of this study was to distinguish the surface roughness value of methacrylate-based composite resin and silorane based composite resins. This research was quasi-experimental. The sample used in this study were methacrylate and silorane based composite resins in discs form, with the size of 6 mm and the thickness of 3 mm, manufactured into 20 specimens and divided into 2 groups. The control group was immersed in the artificial saliva, and the treatment group was applied with 40% hydrogen peroxide. The result of the experiment analyzed using unpaired sample t-test showed significant differences in the average value of the surface roughness after the application of 40% hydrogen peroxide. The average value of methacrylate and silorane based composite resins were 2.744 μm and 3.417 μm, respectively. There was a difference in the surface roughness of methacrylate and silorane based composite resin compounds after the application of 40% hydrogen peroxide. The surface roughness value of the silorane-based composite resin was higher than the methacrylate-based.

  15. Comparison between water and ethanol wet bonding of resin composite to root canal dentin.

    Science.gov (United States)

    Sauro, Salvatore; Di Renzo, Simona; Castagnola, Raffaella; Grande, Nicola M; Plotino, Gianluca; Foschi, Federico; Mannocci, Francesco

    2011-02-01

    To evaluate the bond strength of resin dentin interfaces created with adhesives applied on root dentin using the water wet or ethanol wet bonding technique. The morphology of resin dentin interfaces was evaluated using confocal microscopy. Four experimental resin adhesives (R#A to R#D) and one commercial three-step/etch and rinse adhesive were applied to the root canal dentin of endodontically treated single canal incisors using the water (control) or ethanol wet bonding technique. The ethanol wet bonding substrate was achieved by keeping the root canal immersed in absolute ethanol (100%) for 3 minutes. The root dentin bonded specimens were sectioned into beams, stored in distilled water (24 hours) and finally tested for microtensile bond strengths (tTBS). Additional dentin surfaces were conditioned and bonded as previously described. They were prepared for the microscopy study and finally observed using confocal microscopy. The ethanol wet bonding technique gave higher bond strength values for all the adhesives tested: in Group 1 (water wet bonding technique) no significant difference was found between the resins tested; the only exception being the most hydrophilic Resin #4 showing the highest bond strength values (P < 0.05). In Group 2 (ethanol wet bonding technique) no statistical differences were present between Resin #A and Resin #D. Resin #C showed the highest bond strength values. Confocal microscopy showed better resin diffusion and hybrid layer formation when the ethanol wet bonding was used.

  16. Resin duct characteristics associated with tree resistance to bark beetles across lodgepole and limber pines.

    Science.gov (United States)

    Ferrenberg, Scott; Kane, Jeffrey M; Mitton, Jeffry B

    2014-04-01

    Bark beetles have recently killed billions of trees, yet conifer defenses are formidable and some trees resist attack. A primary anti-insect defense of pines is oleoresin from a system of resin ducts throughout the tree. Resin defense traits are heritable, and evidence suggests that resin duct characteristics are associated with resistance to insects. However, comparisons of resin ducts in trees killed by bark beetles to trees that resisted attack are unavailable. We compared vertical resin duct characteristics (number, density, and size) and growth rates from trees that were "resistant" (survived mass attack) versus "susceptible" (killed by attack) to bark beetles in lodgepole (Pinus contorta) and limber (Pinus flexilis) pines. Resistant trees of both species had significantly more resin ducts in recent growth than susceptible trees. Discriminant analysis (DA) correctly categorized 84% of lodgepole and 92% of limber pines as susceptible/resistant based on combinations of resin duct and growth characteristics from recent 5- through 20-year growth intervals. DA models using measures from only the most recent 5 years of growth correctly categorized 72 and 81% of lodgepole and limber pines, respectively. Comparing resistant to susceptible trees independent of species identity led to the correct categorization of 82% of trees based on factors from 5- to 20-year intervals, and 73% of trees using only resin duct counts from the most recent 5 years. We conclude that resin duct characteristics can be used to assess tree resistance to bark beetles across pine species, and offer a metric for management to enhance pest resistance.

  17. Degree of Conversion and Mechanical Properties of Resin Cements Cured Through Different All-Ceramic Systems.

    Science.gov (United States)

    Lopes, Camila de Carvalho Almança; Rodrigues, Renata Borges; Silva, André Luis Faria E; Simamoto Júnior, Paulo Cézar; Soares, Carlos José; Novais, Veridiana Resende

    2015-10-01

    The aim of this study was to verify the degree of conversion (DC), Vickers microhardness (VH) and elastic modulus (E) of resin cements cured through different ceramic systems. One 1.5-mm-thick disc of each ceramic system (feldspathic, lithium dissilicate and zircônia veneered with feldspathic) was used. Three dual-cured (Allcem, Variolink II and RelyX U200) and one chemically-cured (Multilink) resin cements were activated through ceramic discs. For dual-cured resin cements was used a conventional halogen light-curing unit (Optilux 501 at 650 mW/cm2 for 120 s). Samples cured without the ceramic disc were used as control. The samples were stored at 37 °C for 24 h. ATR/FTIR spectrometry was used to evaluate the extent of polymerization in the samples (n=5). Micromechanical properties - VH and E - of the resin cements (n=5) were measured with a dynamic indentation test. Data were statistically analyzed with two-way ANOVA, Tukey's test and Pearson's correlation (α=0.05). DC was affected only by the type of resin cement (p=0.001). For VH, significant interaction was detected between resin cement and ceramic (p=0.045). The dual-cured resin cements showed no significant differences in mean values for E and significantly higher values than the chemically-cured resin cement. The degree of conversion and the mechanical properties of the evaluated resin cements depend on their activation mode and the type of ceramics used in 1.5 mm thickness. The dual-cured resin cements performed better than the chemically-cured resin cement in all studied properties.

  18. Epoxy Resins in Electron Microscopy

    Science.gov (United States)

    Finck, Henry

    1960-01-01

    A method of embedding biological specimens in araldite 502 (Ciba) has been developed for materials available in the United States. Araldite-embedded tissues are suitable for electron microscopy, but the cutting qualities of the resin necessitates more than routine attention during microtomy. The rather high viscosity of araldite 502 also seems to be an unnecessary handicap. The less viscous epoxy epon 812 (Shell) produces specimens with improved cutting qualities, and has several features—low shrinkage and absence of specimen damage during cure, minimal compression of sections, relative absence of electron beam-induced section damage, etc.—which recommends it as a routine embedding material. The hardness of the cured resin can be easily adjusted by several methods to suit the materials embedded in it. Several problems and advantages of working with sections of epoxy resins are also discussed. PMID:13822825

  19. Process for Molding Nonreinforced (Neat) Resins

    Science.gov (United States)

    Dickerson, G. E.

    1983-01-01

    Void free moldings obtained for neat, condensation, thermosetting resins. Thermally and mechanically treat resin prior to molding to reduce amount of volatiles. With volatiles reduced molding temperature and pressure are applied in way to drive out remaining volatiles during molding.

  20. 21 CFR 172.280 - Terpene resin.

    Science.gov (United States)

    2010-04-01

    ... CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.280 Terpene resin. The food additive terpene resin may be safely used...

  1. A Study on Tensile Behavior and Water Uptake of Wood Powder-Composites Based on Epoxy and Unsaturated Polyester Resins

    Directory of Open Access Journals (Sweden)

    Amir hossein Pirayeshfar

    2013-06-01

    Full Text Available In this study, two kinds of epoxy resins (i.e. high-viscosity and low-viscosity as well as one polyester resin (orthophthalic grade were selected and examined as pure resins and also as a polymeric matrix for producing wood-composites. In this study, tensile properties, water uptake, and degradation of samples in water were also investigated. The results show that addition of wood particles to the thermoset resins strongly impresses on their tensile behavior and water uptake. Tensile studies show that addition of wood powder improves the tensile properties of polyester resin as compared with viscosity epoxy one, although its modulus value is relatively less than that of low viscosity epoxy resin. Water uptake measurements also revealed that pure polyester resin and its related composites possess minimum water uptake and less degradation in water as compared with corresponding epoxy specimens and from which the lowest extent of materials is extracted and migrated to the water even after 50 days immersion in water.

  2. Comparative study of the fatigue strength of five acrylic denture resins.

    Science.gov (United States)

    Gurbuz, Ozlem; Unalan, Fatma; Dikbas, Idil

    2010-11-01

    The aim of this in vitro study was to compare the fatigue resistance of three kinds of heat-polymerized acrylic resins (conventional heat-polymerized, rapid heat-polymerized, high impact acrylic resin), a kind of visible light-cured resin and a kind of self-cured acrylic resin. A total of 60 notched and un-notched specimens (65 mm x 10 mm x 3 mm) were fabricated, 12 from each material. The fatigue resistance was measured by applying repeated three-point bending deflection to the specimens. For statistical analysis, Kruskal-Wallis test followed by Dunn's multiple comparison tests were used. The Kruskal-Wallis test revealed significant differences in the fatigue resistance among some groups (pacrylic resin, but the differences were statistically non-significant according to Dunn's test (p>0.05). High impact acrylic resin was also found to have significantly higher fatigue resistance value than that of self-cured resin and light-cured resin (p0.05). (c) 2010 Elsevier Ltd. All rights reserved.

  3. Method for loading resin beds

    International Nuclear Information System (INIS)

    Notz, K.J.; Rainey, R.H.; Greene, C.W.; Shockley, W.E.

    1978-01-01

    An improved method of preparing nuclear reactor fuel by carbonizing a uranium loaded cation exchange resin provided by contacting a H+ loaded resin with a uranyl nitrate solution deficient in nitrate, comprises providing the nitrate deficient solution by a method comprising the steps of reacting in a reaction zone maintained between about 145 to 200 0 C, a first aqueous component comprising a uranyl nitrate solution having a boiling point of at least 145 0 C with a second aqueous component to provide a gaseous phase containing HNO 3 and a reaction product comprising an aqueous uranyl nitrate solution deficient in nitrate

  4. Uranium sorption by tannin resins

    International Nuclear Information System (INIS)

    Olivares Rieumont, S.; Martinez Luzardo, J.; Torres Hernandez, J.; Lima Cazorla, D. de la Rosa.

    1998-01-01

    The sorption of uranium by immobilised Eucalyptus Saligna Sm. and Lysiloma latisiliqua L tannins was investigated. Immobilization condition were analyzed. These resins resulted suitable adsorbent for the concentration of uranium from aqueous systems. The sorption of uranium is pH dependent. At pH 5.5 maximum in sorption capacity is registered. The presence of appreciable amount of sodium chloride do not have any effect on uranium removal. Carbonate and calcium ions in concentrations similar to these that could be found in sea water and other natural water do not decrease the uranium uptake. Tannin resins can be used several times without an appreciable decay of their sorption capacity

  5. Determination of processed soybean meal degradability by Pinus ...

    African Journals Online (AJOL)

    Determination of processed soybean meal degradability by Pinus eldarica methanol extract. ... Protected soybean meal is an important part of high producing dairy cow diet and many methods are used for its safe and economic processing. Pinus eldarica contains xylose and resins and results show that these components ...

  6. Fracture Resistance of Endodontically Treated Teeth Restored with Biodentine, Resin Modified GIC and Hybrid Composite Resin as a Core Material.

    Science.gov (United States)

    Subash, Dayalan; Shoba, Krishnamma; Aman, Shibu; Bharkavi, Srinivasan Kumar Indu; Nimmi, Vijayan; Abhilash, Radhakrishnan

    2017-09-01

    The restoration of a severely damaged tooth usually needs a post and core as a part of treatment procedure to provide a corono - radicular stabilization. Biodentine is a class of dental material which possess high mechanical properties with excellent biocompatibility and bioactive behaviour. The sealing ability coupled with optimum physical properties could make Biodentine an excellent option as a core material. The aim of the study was to determine the fracture resistance of Biodentine as a core material in comparison with resin modified glass ionomer and composite resin. Freshly extracted 30 human permanent maxillary central incisors were selected. After endodontic treatment followed by post space preparation and luting of Glass fibre post (Reforpost, Angelus), the samples were divided in to three groups based on the type of core material. The core build-up used in Group I was Biodentine (Septodont, France), Group II was Resin-Modified Glass Ionomer Cement (GC, Japan) and Group III was Hybrid Composite Resin (TeEconom plus, Ivoclar vivadent). The specimens were subjected to fracture toughness using Universal testing machine (1474, Zwick/Roell, Germany) and results were compared using One-way analysis of variance with Tukey's Post hoc test. The results showed that there was significant difference between groups in terms of fracture load. Also, composite resin exhibited highest mean fracture load (1039.9 N), whereas teeth restored with Biodentine demonstrated the lowest mean fracture load (176.66 N). Resin modified glass ionomer exhibited intermediate fracture load (612.07 N). The primary mode of failure in Group I and Group II was favourable (100%) while unfavourable fracture was seen in Group III (30%). Biodentine, does not satisfy the requirements to be used as an ideal core material. The uses of RMGIC's as a core build-up material should be limited to non-stress bearing areas. Composite resin is still the best core build-up material owing to its high fracture

  7. Modification of graphene with silica nanoparticles for use in hybrid network formation from epoxy, novolac, and epoxidized novolac resins by sol-gel method: Investigation of thermal properties

    Directory of Open Access Journals (Sweden)

    A. Mousavi

    2018-03-01

    Full Text Available Thermal stability of hybrid composites prepared from epoxy, novolac, and epoxidized-novolac resins and also modified graphene oxide (SFGO was studied. SFGO was prepared by covering graphene oxide with silica nanoparticles and a bifunctional silane modifier. The first hybrid was prepared from SFGO and silane-modified epoxy resin. The second one was prepared from SFGO, and silane-modified epoxy and novolac resins. The third hybrid was formed from SFGO, silane-modified novolac, and epoxidized novolac resins. Fourier transform infrared (FT-IR, X-ray photoelectron spectroscopy (XPS, X-ray diffraction (XRD, and thermogravimetric analysis (TGA results showed that modification of graphene oxide was carried out successfully. TGA results show that degradation temperature and char residue of resins were increased through their incorporation into hybrid network with SFGO. In addition, the most increase of char residue was observed for the hybrid composites formed from SFGO and modified novolac and epoxy resins.

  8. Effect of green tea extract and mouthwash without alcohol on Candida albicans biofilm on acrylic resin.

    Science.gov (United States)

    Antunes, Débora P; Salvia, Ana Carolina R D; de Araújo, Rodrigo M; Di Nicoló, Rebeca; Koga Ito, Cristiane Y; de Araujo, Maria A M

    2015-12-01

    To evaluate the effect of aqueous extract of green tea and the oral antiseptic without alcohol, on Candida albicans biofilm formation to heat-curing acrylic resin plates. Candida is associated with oral candidiasis in poorly cleaned dentures. Standardised specimens of heat-cured (Conv; n = 30) or microwave-cured acrylic resin (Mw; n = 30) were obtained and divided into six groups (n = 10): G1 = Conv resin and green tea aqueous extract, G2 = Conv resin and mouthwash, G3 = control of Conv resin, G4 = Mw resin and green tea aqueous extract, G5 = Mw resin and mouthwash and G6 = control of Mw-cured resin. The specimens were contaminated with 10 ml of Sabouraud dextrose broth inoculated with 0.1 ml of standard suspension containing 1 × 10(6) cells/ml of C. albicans and incubated for 24 h at 37°C. After this period, they were immersed in the aqueous extract or in mouthwash for 15 min. The control groups were treated with sterile distilled water. Aliquots of 0.1 ml were plated on Sabouraud dextrose agar and incubated at 37°C for 24 h. The numbers of colony-forming units per test specimen (CFU/TS) were calculated, and the results statistically analysed by two-way anova and Tukey's tests (5%). Statistically significant difference was observed for the aqueous extract groups (G1; 33.65%) and mouthwash (G2; 17.06%), when compared to control (G3; 100%), for Conv resin. For the Mw resin, there was significant difference between mouthwash (G5; 43.16%) and control (G6; 100%). The aqueous extract of green tea and mouthwash led to a reduction in the number of viable fungal cells in biofilm formed on acrylic resin. © 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd.

  9. How much do resin-based dental materials release? A meta-analytical approach.

    Science.gov (United States)

    Van Landuyt, K L; Nawrot, Tim; Geebelen, B; De Munck, J; Snauwaert, J; Yoshihara, K; Scheers, Hans; Godderis, Lode; Hoet, P; Van Meerbeek, B

    2011-08-01

    Resin-based dental materials are not inert in the oral environment, and may release components, initially due to incomplete polymerization, and later due to degradation. Since there are concerns regarding potential toxicity, more precise knowledge of the actual quantity of released eluates is necessary. However, due to a great variety in analytical methodology employed in different studies and in the presentation of the results, it is still unclear to which quantities of components a patient may be exposed. The objective of this meta-analytical study was to review the literature on the short- and long-term release of components from resin-based dental materials, and to determine how much (order of magnitude) of those components may leach out in the oral cavity. Out of an initial set of 71 studies, 22 were included. In spite of the large statistical incertitude due to the great variety in methodology and lack of complete information (detection limits were seldom mentioned), a meta-analytical mean for the evaluated eluates was calculated. To relate the amount of potentially released material components with the size of restorations, the mean size of standard composite restorations was estimated using a 3D graphical program. While the release of monomers was analyzed in many studies, that of additives, such as initiators, inhibitors and stabilizers, was seldom investigated. Significantly more components were found to be released in organic than in water-based media. Resin-based dental materials might account for the total burden of orally ingested bisphenol A, but they may release even higher amounts of monomers, such as HEMA, TEGDMA, BisGMA and UDMA. Compared to these monomers, similar or even higher amounts of additives may elute, even though composites generally only contain very small amounts of additives. A positive correlation was found between the total quantity of released eluates and the volume of extraction solution. There is a clear need for more accurate

  10. Method of removing contaminants from plastic resins

    Energy Technology Data Exchange (ETDEWEB)

    Bohnert, George W. (Harrisonville, MO); Hand, Thomas E. (Lee' s Summit, MO); DeLaurentiis, Gary M. (Jamestown, CA)

    2008-11-18

    A method for removing contaminants from synthetic resin material containers using a first organic solvent system and a second carbon dioxide system. The organic solvent is utilized for removing the contaminants from the synthetic resin material and the carbon dioxide is used to separate any residual organic solvent from the synthetic resin material.

  11. Method of removing contaminants from plastic resins

    Energy Technology Data Exchange (ETDEWEB)

    Bohnert,George W. (Harrisonville, MO); Hand,Thomas E. (Lee' s Summit, MO); Delaurentiis,Gary M. (Jamestown, CA)

    2007-08-07

    A method for removing contaminants from synthetic resin material containers using a first organic solvent system and a second carbon dioxide system. The organic solvent is utilized for removing the contaminants from the synthetic resin material and the carbon dioxide is used to separate any residual organic solvent from the synthetic resin material.

  12. Method for removing contaminants from plastic resin

    Science.gov (United States)

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2008-12-30

    A method for removing contaminants from synthetic resin material containers using a first organic solvent system and a second carbon dioxide system. The organic solvent is utilized for removing the contaminants from the synthetic resin material and the carbon dioxide is used to separate any residual organic solvent from the synthetic resin material.

  13. New acrylic resin composite with improved thermal diffusivity.

    Science.gov (United States)

    Messersmith, P B; Obrez, A; Lindberg, S

    1998-03-01

    Studies have shown that physical characteristics of denture base materials may affect patient acceptance of denture prostheses by altering sensory experience of food during mastication. Thermal diffusivity is one material property that has been cited as being important in determining gustatory response, with denture base acrylic resins having low thermal diffusivity compared with denture base metal alloys. This study prepared and characterized experimental acrylic resin composite material with increased thermal diffusivity. Sapphire (Al2O3) whiskers were added to conventional denture base acrylic resin during processing to achieve loadings of 9.35% and 15% by volume. Cylindrical test specimens containing an embedded thermocouple were used to determine thermal diffusivity over a physiologic temperature range (0 degree to 70 degrees C). Thermal diffusivities of the sapphire containing composites were found to be significantly higher than the unmodified acrylic resin. Thermal diffusivity was found to increase in proportion to the volume percentage of sapphire filler, which suggested that the high aspect ratio ceramic particles formed a pathway for heat conduction through the insulating polymer matrix. The thermal diffusivity of denture base acrylic resin was increased by the addition of thermally conducting sapphire whiskers.

  14. Reinforcement of Aluminum Oxide Filler on the Flexural Strength of Different Types of Denture Base Resins: An In vitro Study

    Science.gov (United States)

    Srivatsa, G.; Shetty, Rohit; Huddar, Dayanand; Sankeshwari, Banashree; Chopade, Swapnil

    2017-01-01

    Introduction Acrylic resins have been used extensively for the fabrication of denture bases because of their aesthetic qualities, ease of manipulation and repairability. Flexural fatigue of the denture base has been shown to be a factor in the clinical failure of polymethyl methacrylate resin dentures. Also, the fracture can result from impact, fatigue or degradation of the base material. Hence, there is a need to increase the strength of denture base resins. Aim To evaluate the effect of reinforcing alumina oxide filler on the flexural strength of different acrylic resins. Materials and Methods A total of 180 acrylic specimens were fabricated, which were divided into three groups self cure acrylic resin (SC), conventional heat cure resin (HC) and high strength heat cure resin (HI). Each group was divided into four subgroups i.e., control group and the specimens of the remaining three groups were reinforced with aluminum oxide (Al2O3) powder by 5%, 10% and 15% by weight. Specimens were stored in distilled water for one week; flexural strength was tested by universal testing machine. Results were analysed by one-way analysis of variance and post-hoc Tukey paired group comparison tests. Results Flexural strength of SC increased by 9%, 13% and 19%, Flexural strength of HC increased by 8%, 15% and 19% and that of HI increased by 21%, 26% and 29% compared to control group by adding 5%,10% and 15% of alumina filler (p-value acrylic resin, conventional heat cure acrylic resin and high strength heat cure acrylic resin increased the flexural strength. Increasing the flexural strength of the acrylic resin base material could lead to more clinical success. PMID:28571274

  15. [Effect of bleaching agents on the color of indirect and direct composite resins].

    Science.gov (United States)

    Xing, Wenzhong; Jiang, Tao; Chen, Xiaodong; Wang, Yining

    2014-09-01

    To evaluate the effect of bleaching agents on the color of indirect and direct composite resins. Five resin composite materials were tested in this in vitro study. The five composites were as follow: two indirect composite resins (Adoro SR, Ceramage) and three direct composite resins (Filtek Z350, Clearfil Majesty Esthetic, and Gradia Direct Anterior). For each material, twenty disk-shaped specimens were prepared and randomly divided into five groups according to the color parameters of specimens before bleaching treatment. The composite resin specimens were treated by one of five sample solutions which were at-home bleaching agents (10% and 15% carbarmide peroxide), in- office bleaching agents (38% H(2)O(2) and 35%H(2)O(2)) and deionized water (control group). The color parameters of specimens were measured by spectrophotometer at baseline and after bleaching treatments. The color differences (ΔE values) between baseline and post-treatments were calculated. The data of color differences were evaluated statistically using two-way analysis with a significance level of 0.05. The color changes of the resin composites were less than 2.0 after bleaching agent treatment, therefore were not perceptible. Slight increase of L(*) values and decrease of C(*)ab values in color parameters of specimens were observed. There were statistically significant differences in ΔE values for different bleaching treatments and resin materials (P = 0.001). The bleaching agents did not affect the color of indirect and direct composite resins tested.

  16. Temperature rise during polymerization of different cavity liners and composite resins.

    Science.gov (United States)

    Karatas, Ozcan; Turel, Verda; Bayindir, Yusuf Ziya

    2015-01-01

    The purpose of this study was to evaluate the thermal insulating properties of different light curing cavity liners and composite resins during light emitting diode (LED) curing. Sixty-four dentin discs, 1 mm thick and 8 mm in diameter, were prepared. Specimens were divided into four groups. Calcium hydroxide (Ca[OH]2), resin-modified glass ionomer cement, flowable composite and adhesive systems were applied to dentin discs according to the manufacturers' instructions. The rise in temperature during polymerization with a LED curing unit (LCU) was measured using a K-type thermocouple connected to a data logger. Subsequently, all specimens were randomly divided into one of two groups. A silorane-based composite resin and a methacrylate-based composite resin were applied to the specimens. Temperature rise during polymerization of composite resins with LCU were then measured again. Data were analyzed using one-way ANOVA and post hoc Tukey analyses. There were significant differences in temperature rise among the liners, adhesives, and composite resins (P < 0.05). Silorane-based composite resin exhibited significantly greater temperature rises than methacrylate-based resin (P < 0.05). The smallest temperature rises were observed in Ca(OH)2 specimens. Thermal insulating properties of different restorative materials are important factors in pulp health. Bonding agents alone are not sufficient to protect pulp from thermal stimuli throughout curing.

  17. Effect of disinfection and storage on the flexural strength of ocular prosthetic acrylic resins.

    Science.gov (United States)

    Goiato, Marcelo C; dos Santos, Daniela M; Moreno, Amália; Iyda, Mariana G; Rezende, Maria C R A; Haddad, Marcela F

    2012-06-01

    To evaluate the influence of chemical disinfection and storage duration on the flexural strength of acrylic resins commonly used to make ocular prostheses. A total of 260 samples were manufactured with N1 resin and colourless resin. Both resins were thermopolymerised using a microwave oven. Samples were stored and periodically disinfected and were divided into groups: control (no disinfection) (I), neutral soap (II), Opti-free (III), Efferdent (IV), 1% hypochlorite (V) or 4% chlorhexidine (VI). The flexural strength was measured before and after 60 and 120 days of storage. Data were analysed by anova and Tukey test (0.05). The flexural strength of the N1 resin was higher than that for the colourless resin. There was a significant difference in the flexural strength before and after 60 and 120 days of storage with disinfection, regardless of the resin and disinfectant. Group I in the initial period exhibited greater flexural strength, with significant difference only in group VI after 120 days. It can be concluded that the flexural strength only changed after 120 days of storage for samples disinfected with chlorhexidine. However, all flexural strength values obtained herein were acceptable clinical limits for the acrylic resins. © 2011 The Gerodontology Society and John Wiley & Sons A/S.

  18. Antibacterial effect of composite resins containing quaternary ammonium polyethyleneimine nanoparticles

    International Nuclear Information System (INIS)

    Yudovin-Farber, Ira; Beyth, Nurit; Weiss, Ervin I.; Domb, Abraham J.

    2010-01-01

    Quaternary ammonium polyethyleneimine (QA-PEI)-based nanoparticles were synthesized by crosslinking with dibromopentane followed by N-alkylation with various alkyl halides and further N-methylation with methyl iodide. Insoluble pyridinium-type particles were prepared by suspension polymerization of 4-vinyl pyridine followed by N-alkylation with alkyl halides. Polyamine-based nanoparticles embedded in restorative composite resin at 1% w/w were tested for antibacterial activity against Streptococcus mutans using direct contact test. Activity analysis revealed that the alkyl chain length of the QA-PEI nanoparticles plays a significant role in antibacterial activity of the reagent. The most potent compound was octyl-alkylated QA-PEI embedded in restorative composite resin at 1% w/w that totally inhibited S. mutans growth in 3-month-aged samples. This data indicates that restorative composite resin with antibacterial properties can be produced by the incorporation of QA-PEI nanoparticles.

  19. Antibacterial effect of composite resins containing quaternary ammonium polyethyleneimine nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Yudovin-Farber, Ira [Hebrew University of Jerusalem, Department of Medicinal Chemistry and Natural Products, School of Pharmacy, Faculty of Medicine (Israel); Beyth, Nurit; Weiss, Ervin I. [Hebrew University of Jerusalem, Department of Prosthodontics, Faculty of Dentistry (Israel); Domb, Abraham J., E-mail: avid@ekmd.huji.ac.i [Hebrew University of Jerusalem, Department of Medicinal Chemistry and Natural Products, School of Pharmacy, Faculty of Medicine (Israel)

    2010-02-15

    Quaternary ammonium polyethyleneimine (QA-PEI)-based nanoparticles were synthesized by crosslinking with dibromopentane followed by N-alkylation with various alkyl halides and further N-methylation with methyl iodide. Insoluble pyridinium-type particles were prepared by suspension polymerization of 4-vinyl pyridine followed by N-alkylation with alkyl halides. Polyamine-based nanoparticles embedded in restorative composite resin at 1% w/w were tested for antibacterial activity against Streptococcus mutans using direct contact test. Activity analysis revealed that the alkyl chain length of the QA-PEI nanoparticles plays a significant role in antibacterial activity of the reagent. The most potent compound was octyl-alkylated QA-PEI embedded in restorative composite resin at 1% w/w that totally inhibited S. mutans growth in 3-month-aged samples. This data indicates that restorative composite resin with antibacterial properties can be produced by the incorporation of QA-PEI nanoparticles.

  20. Resin-composite blocks for dental CAD/CAM applications.

    Science.gov (United States)

    Ruse, N D; Sadoun, M J

    2014-12-01

    Advances in digital impression technology and manufacturing processes have led to a dramatic paradigm shift in dentistry and to the widespread use of computer-aided design/computer-aided manufacturing (CAD/CAM) in the fabrication of indirect dental restorations. Research and development in materials suitable for CAD/CAM applications are currently the most active field in dental materials. Two classes of materials are used in the production of CAD/CAM restorations: glass-ceramics/ceramics and resin composites. While glass-ceramics/ceramics have overall superior mechanical and esthetic properties, resin-composite materials may offer significant advantages related to their machinability and intra-oral reparability. This review summarizes recent developments in resin-composite materials for CAD/CAM applications, focusing on both commercial and experimental materials. © International & American Associations for Dental Research.

  1. Viscoelastic behavior of multiwalled carbon nanotubes into phenolic resin

    Energy Technology Data Exchange (ETDEWEB)

    Botelho, Edson Cocchieri; Costa, Michelle Leali; Braga, Carlos Isidoro, E-mail: ebotelho@feg.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Guaratingueta, SP (Brazil). Dept. de Materiais e Tecnologia; Burkhart, Thomas [Institut fuer Verbundwerkstoffe GmbH, Kaiserslautern, (Germany); Lauke, Bernd [Leibniz-Institut fuer Polymerforschung, Dresden (Germany)

    2013-11-01

    Nanostructured polymer composites have opened up new perspectives for multi-functional materials. In particular, carbon nanotubes (CNTs) have the potential applications in order to improve mechanical and electrical performance in composites with aerospace application. This study focuses on the viscoelastic evaluation of phenolic resin reinforced carbon nanotubes, processed by using two techniques: aqueous-surfactant solution and three roll calender (TRC) process. According to our results a relative small amount of CNTs in a phenolic resin matrix is capable of enhancing the viscoelastic properties significantly and to modify the thermal stability. Also has been observed that when is used TRC process, the incorporation and distribution of CNT into phenolic resin is more effective when compared with aqueous solution dispersion process. (author)

  2. Characterization of selected LDEF polymer matrix resin composite materials

    Science.gov (United States)

    Young, Philip R.; Slemp, Wayne S.; Witte, William G., Jr.; Shen, James Y.

    1991-01-01

    The characterization of selected graphite fiber reinforced epoxy (934 and 5208) and polysulfone (P1700) matrix resin composite materials which received 5 years and 10 months of exposure to the LEO environment on the Long Duration Exposure Facility is reported. Resin loss and a decrease in mechanical performance as well as dramatic visual effects were observed. However, chemical characterization including infrared, thermal, and selected solution property measurements showed that the molecular structure of the polymeric matrix had not changed significantly in response to this exposure. The potential effect of a silicon-containing molecular contamination of these specimens is addressed.

  3. Occupational exposure to epoxy resins

    NARCIS (Netherlands)

    Terwoert, J.; Kersting, K.

    2014-01-01

    Products based on epoxy resins as a binder have become popular in various settings, among which the construction industry and in windmill blade production, as a result of their excellent technical properties. However, due to the same properties epoxy products are a notorious cause of allergic skin

  4. Degraded Crater

    Science.gov (United States)

    2004-01-01

    21 October 2004 Near the center of this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image lies the degraded remnants of an old meteor impact crater. The terrain in which it occurs is a heavily eroded, north middle-latitude surface. The image is located in the fretted terrains north of Arabia Terra near 41.3oN, 305.8oW. The image covers an area about 3 km (1.9 mi) wide and sunlight illuminates the scene from the lower left.

  5. Effect of Different Liners on Fracture Resistance of Premolars Restored with Conventional and Short Fiber-Reinforced Composite Resins.

    Science.gov (United States)

    Shafiei, Fereshteh; Doozandeh, Maryam; Ghaffaripour, Dordaneh

    2018-01-11

    To see whether applying four different liners under short fiber-reinforced composite (SFRC), everX Posterior, compared to conventional composite resin, Z250, affected their strengthening property in premolar MOD cavities. Mesio-occluso-distal (MOD) cavities were prepared in 120 sound maxillary premolars divided into 10 groups (n = 12) in terms of two composite resin types and 4 liners or no liner. For each composite resin, in 5 groups no liner, resin-modified glass ionomer (RMGI), conventional flowable composite (COFL), self-adhesive flowable composite resin (SAFL), and self-adhesive resin cement (SARC) were applied prior to restoring incrementally. After water storage and thermocycling, static fracture resistance was tested. Data (in Newtons) were analyzed using two-way ANOVA (α = 0.05). Fracture resistance was significantly affected by composite resin type (p = 0.02), but not by the liner (p > 0.05). The interaction of the two factors was not statistically significant (p > 0.05). SFRC exhibited higher fracture strength (1470 ± 200 N) compared to conventional composite resin (1350 ± 290), irrespective of the application of liners. Application of SARC and SAFL liners led to a higher number of restorable fractures for both composite resins. The four liners can be used without interfering with the higher efficacy of SFRC, compared to conventional composite resins, to improve the fracture strength of premolar MOD cavities. © 2018 by the American College of Prosthodontists.

  6. In vitro comparative evaluation of the effect of two different fiber reinforcements on the fracture toughness of provisional restorative resins.

    Science.gov (United States)

    Kamble, Vaibhav D; Parkhedkar, Rambhau D

    2012-01-01

    Fracture of provisional fixed partial denture (FPD) may jeopardize the success of provisional prosthodontic treatment phase and cause patient discomfort. The aim of this study was to compare the fracture toughness of the Polymethyl Methacrylate (PMMA) resin and Bis-Acryl Composite (BAC) resin reinforced with the Polyethylene and Glass fibers. Three groups (N=10) of each of the two materials were prepared for the fracture toughness test. Two groups had the different reinforcements and group without reinforcement served as the control. The mean fracture toughness (MPa.m½ ) was compared by One-way ANOVA, followed by the Scheffe analysis. Fracture toughness between fiber-reinforced PMMA and BAC resin was compared by the independent samples t test. For the controls, the fracture toughness for PMMA resin (0.91) was significantly lower than for the BAC resin (1.19). Glass fiber reinforcement produced significantly higher fracture toughness for both, PMMA (1.48) and BAC (1.82) resin, but the Polyethylene fibers did not (0.95 for PMMA and 1.23 for BAC resin). Among the reinforced groups, Silane impregnated Glass fibers showed highest fracture toughness for the BAC resin (1.82). Of two fiber reinforcement methods evaluated, Glass fiber reinforcement for the PMMA and BAC resin produced highest fracture toughness. On the basis of this in--vitro study, the use of Glass and Polyethylene fibers tested may be an effective way to reinforce resins used to fabricate fixed provisional restorations.

  7. A comparison of fatigue crack growth in resin composite, dentin and the interface.

    Science.gov (United States)

    Soappman, Matthew J; Nazari, Ahmad; Porter, Judith A; Arola, D

    2007-05-01

    The objective of this in vitro study was to evaluate the fatigue crack growth properties of the dentin/resin adhesive interface. Compact tension (CT) specimens were prepared from coronal dentin, resin composite, and dentin bonded to resin composite using Optibond Solo Plus adhesive. All specimens were then subjected to cyclic Mode I loading while fully hydrated at a stress ratio of R=0.1 and frequency of 5 Hz. Steady state fatigue crack growth was modeled using the Paris Law in terms of the exponent (m) and coefficient (C). The average fatigue crack growth rates in the resin composite ranged from 1.6E-06 to 3.8E-05 mm/cycle with growth occurring over a stress intensity range from 0.40 to 0.77 MPa m(1/2); the average growth exponent was 6.9+/-3.1. Average fatigue crack growth rates for the dentin/resin interface specimens ranged from 5.5E-07 to 6.4E-03 mm/cycle with growth occurring over a stress intensity range from 0.37 to 0.64 MPa m(1/2). The Paris Law exponent for these specimens ranged from 16resin and at the adhesive-dentin interface. In addition, many of the dentin/resin specimens underwent unstable fracture at a comparatively low stress intensity range without undergoing cyclic crack growth. The dentin/resin adhesive interface proved to be significantly more sensitive to fatigue crack growth than either dentin or resin composite. Variation in the cyclic crack growth responses of the dentin/resin interface specimens suggests that the interface, and particularly the adhesive resin, exhibits lower resistance to crack initiation and growth in comparison to dentin.

  8. Resin composites: strength of the bond to dentin versus mechanical properties.

    Science.gov (United States)

    Thomsen, Kasper Boel; Peutzfeldt, Anne

    2007-03-01

    This study (1) investigated whether the combination of an adhesive system from one manufacturer with a resin composite from the same manufacturer provides superior bonding of the resin composite to dentin compared with the combination of an adhesive system from one manufacturer with a resin composite from another manufacturer, and (2) tested for a possible influence on bond strength of mechanical properties of the resin composite. After application of an adhesive system, a resin composite was bonded to flattened human dentin and tested in shear after 1 week. Five adhesive systems (AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, Optibond Solo Plus, and Xeno III) were tested with each of five resin composites (Tetric Ceram, Filtek Supreme, Clearfil AP-X, Premise, and EsthetX). The mechanical properties flexural strength and flexural modulus were determined by three-point loading. Bond strengths were influenced by the brand of adhesive system (P resin composite (P resin composite from the same manufacturer did not provide bond strengths that were superior to those obtained when an adhesive system from one manufacturer was combined with a resin composite from another manufacturer. Independent of the brand of resin composite, the adhesive system Clearfil SE Bond mediated the highest bond strength to dentin. For each adhesive system, the resin composite Clearfil AP-X resulted in the highest bond strength to dentin. Significant positive correlations were found between bond strength and flexural strength (P < 0.0026, r = 0.21) and between bond strength and flexural modulus (P < 0.0017, r = 0.22).

  9. Evaluation of the esthetic effect of resin cements and try-in pastes on ceromer veneers.

    Science.gov (United States)

    Xing, Wenzhong; Jiang, Tao; Ma, Xiao; Liang, Shanshan; Wang, Zhejun; Sa, Yue; Wang, Yining

    2010-01-01

    To evaluate the influence of various shades of resin cements on the final color of ceromer veneers and analyse the agreement of resin cements and corresponding try-in pastes. Ceromer disks (Ceramage, 1.0mm×10mm diameter) were bonded to resin background disks (3.0mm×10mm diameter) using five shades of resin cements (RelyX Veneer), whilst butylphthalate was placed between ceromer and resin background as the control group (n=5). The corresponding try-in pastes were placed between ceromer and resin background disks using the specimens of the control group. After colorimetric evaluations, the thickness of ceromer disks was reduced to 0.8 and 0.5mm. Color measurements were repeated at each thickness. To analyse masking ability of the cement, resin background disks with 0.1mm thick cement layer were fabricated using five shades of resin cements (n=5). Two-way ANOVA of ΔE values of cement shades and control group revealed significant differences in cement shade and thickness, and their interaction (p2.0) in 0.5mm thick specimens and WO shade in 0.8mm thick specimens. There were no perceptible color differences between resin cements and corresponding try-in pastes. The effect of resin cements on the final color of ceromer veneers depended on cement shades and thickness of ceromer. The color of resin cements and corresponding try-in pastes achieved high agreement. Copyright © 2010 Elsevier Ltd. All rights reserved.

  10. Effect of proximal box elevation with resin composite on marginal quality of ceramic inlays in vitro.

    Science.gov (United States)

    Frankenberger, Roland; Hehn, Julia; Hajtó, Jan; Krämer, Norbert; Naumann, Michael; Koch, Andreas; Roggendorf, Matthias J

    2013-01-01

    The objective of this study was to evaluate the marginal quality and resin-resin transition of milled CAD/CAM glass-ceramic inlays in deep proximal cavities with and without 3-mm proximal box elevation (PBE) using resin composites before and after thermomechanical loading. MOD cavities with one proximal box beneath the cementoenamel junction were prepared in 48 extracted human third molars. Proximal boxes ending in dentin were elevated for 3 mm with different resin composites (RelyX Unicem, G-Cem, and Maxcem Elite as self-adhesive resin cements and Clearfil Majesty Posterior as restorative resin composite in one or three layers bonded with AdheSE) or left untreated. IPS Empress CAD inlays were luted with Syntac and Variolink II (n = 8). Marginal quality as well as the PBE-ceramic interface were analyzed under an SEM using epoxy resin replicas before and after thermomechanical loading (100,000 × 50 N and 2,500 thermocycles between +5°C and +55°C). Bonding glass-ceramic directly to dentin showed the highest amounts of gap-free margins in dentin (92%, p resin composite applied in three layers achieved 84% gap-free margins in dentin; PBE with self-adhesive resin cements exhibited significantly more gaps in dentin (p resin composite, PBE may be an alternative to ceramic bonding to dentin. Self-adhesive resin cements seem not suitable for this indication. For deep proximal boxes ending in dentin, a PBE may be an alternative to conventional techniques.

  11. Motor degradation prediction methods

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, J.R.; Kelly, J.F.; Delzingaro, M.J.

    1996-12-01

    Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor`s duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures.

  12. Motor degradation prediction methods

    International Nuclear Information System (INIS)

    Arnold, J.R.; Kelly, J.F.; Delzingaro, M.J.

    1996-01-01

    Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor's duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures

  13. Degradation Signatures of Open Ocean Microplastic Debris

    Science.gov (United States)

    Lavender Law, K. L.; Donohue, J. L.; Collins, T.; Proskurowsi, G.; Andrady, A. L.

    2016-02-01

    Microplastics collected from the open ocean offer few clues about their origin and history. There is currently no method to determine how long ocean plastic has undergone environmental weathering, how quickly fragmentation has occurred, or how small microplastic particles will ultimately become before (or if) they are fully degraded by microbial action. In the current absence of results from laboratory and field experiments designed to address these questions, we meticulously examined physical and chemical characteristics of open ocean microplastic particles collected over a 16-year period for clues about their weathering history. More than 1000 microplastic particles collected in the western North Atlantic between 1991 and 2007 were analyzed to determine polymer type, material density, mass and particle size, and were used to create a detailed catalogue of common microscopic surface features likely related to environmental exposure and weathering. Polyethylene and polypropylene, the two buoyant resins most commonly collected at the sea surface, can typically be distinguished by visual microscopy alone, and their particular characteristics lead us to hypothesize that these two resins weaken and fragment in different ways and on different time scales. A subset of resin pellets collected at sea were also analyzed using FTIR-ATR and/or FTIR microscopy for signatures of chemical degradation (e.g., carbonyl index) that are related to physical weathering characteristics such as color, quantified by the yellowness index.

  14. Bond strength of resin composite to light activated bleached enamel

    African Journals Online (AJOL)

    2015-09-02

    Sep 2, 2015 ... Conclusion: The various irradiation treatments following the application of the whiteness HP bleaching agent to enamel did not significantly reduce the µTBS within a 14‑day period. Key words: Bleaching agents, lasers, lasers neodymium: yttrium aluminum garnet, resin bonding, tooth bleaching. Date of ...

  15. Isothermal relaxation current and microstructure changes of thermally aged polyester films impregnated by epoxy resin

    Science.gov (United States)

    Jiang, Xiongwei; Sun, Potao; Peng, Qingjun; Sima, Wenxia

    2018-01-01

    In this study, to understand the effect of thermal aging on polymer films degradation, specimens of polyester films impregnated by epoxy resin with different thermal aging temperatures (80 and 130 °C) and aging times (500, 1600, 2400 and 3000 h) are prepared, then charge de-trapping properties of specimens are investigated via the isothermal relaxation current (IRC) measurement, the distributions of trap level and its corresponding density are obtained based on the modified IRC model. It is found that the deep trap density increases remarkably at the beginning of thermal aging (before 1600 h), but it decreases obviously as the aging degree increases. At elevated aging temperature and, in particular considering the presence of air gap between two-layer insulation, the peak densities of deep traps decrease more significant in the late period of aging. It can be concluded that it is the released energy from de-trapping process leads to the fast degradation of insulation. Moreover, after thermal aging, the microstructure changes of crystallinity and molecular structures are analyzed via the x-ray diffraction experiment and Fourier transform infrared spectrometer. The results indicate that the variation of the deep trap density is closely linked with the changes of microstructure, a larger interface of crystalline/amorphous phase, more defects and broken chains caused by thermal aging form higher deep trap density stored in the samples.

  16. The transverse strength of acrylic resin after Coleus amboinicus, Lour extract solution immersion

    Directory of Open Access Journals (Sweden)

    Devi Rianti

    2006-12-01

    Full Text Available A laboratoric experimental study was conducted on the transverse strength of acrylic resin after Coleus amboinicus, Lour extract solution immersion. The aim of this study is to know the difference of acrylic resin transverse strengths caused by immersion time variations in a concentrate solution. The study was carried out on unpolished acrylic resin plates with 65 × 10 × 2,5 mm dimension; solution with 15% Coleus amboinicus, Lour extract, and 30, 60, 90 days immersion times to measure the transverse strength and sterilized aquadest was used as control. Acrylic resin plates transverse strength was measured using Autograph AG-10 TE. The data was analyzed using One-Way Anova and LSD with 5% degree of significance. The result showed that longer immersion time will decrease the transverse strength of the acrylic resin plates. After 90 days immersion time, the transverse strength decrease is still above the recommended standard transverse strength.

  17. An evaluation of organic substance fraction removal during ion exchange with Miex-DOC resin.

    Science.gov (United States)

    Wolska, Małgorzata

    2015-07-01

    In this study, the usefulness of Miex-DOC resin in eliminating organic substances and their fractions from water sources for drinking water was evaluated. The objects of study were samples from three surface water sources and one infiltration water source taken at water treatment plants before treatment in technical conditions. In particular, the effectiveness of removing biodegradable and non-biodegradable fractions as a function of resin dosages and water-resin contact times was evaluated. The ion exchange process with the Miex-DOC resin achieved a high effectiveness in removing aromatic non-biodegradable organic substances, and therefore a reduction in UV254 absorbance. The biodegradable fraction is much less susceptible to removal yet its removal effectiveness allows for a significant reduction in hazards connected with secondary microorganism development. The results of this study indicate the possibility of using ion exchange with the Miex-DOC resin for effective removal of disinfection by-product precursors.

  18. A randomized controlled 30 years follow up of three conventional resin composites in Class II restorations

    DEFF Research Database (Denmark)

    Pallesen, Ulla; van Dijken, Jan WV

    2015-01-01

    Objective. The aim of this 30 year randomized controlled study was to evaluate, by intrain-dividual comparisons, the durability of three conventional resin composites in Class IIrestorations. Methods. Each of 30 participants, 21 female and 9 male (mean age 30 years, range 20–43),received at least...... three (one set) as similar as possible Class II restorations of moderate size.After cavity preparation, the three cavities were chosen at random to be restored with twochemical-cured (P10, Miradapt) and one light-cured resin composite (P30). A chemical-curedenamel bonding agent was applied after etching...... resin composites (p = 0.45).The variables tooth type, cavity size, age, and gender of the participants did not significantlyaffect the probability of failure. Significance. The three conventional resin composites showed good clinical performance dur-ing the 30 year evaluation. The chemical cured resin...

  19. Attribute Based Selection of Thermoplastic Resin for Vacuum Infusion Process: A Decision Making Methodology

    DEFF Research Database (Denmark)

    Raghavalu Thirumalai, Durai Prabhakaran; Lystrup, Aage; Løgstrup Andersen, Tom

    2012-01-01

    The composite industry looks toward a new material system (resins) based on thermoplastic polymers for the vacuum infusion process, similar to the infusion process using thermosetting polymers. A large number of thermoplastics are available in the market with a variety of properties suitable...... for different engineering applications, and few of those are available in a not yet polymerised form suitable for resin infusion. The proper selection of a new resin system among these thermoplastic polymers is a concern for manufactures in the current scenario and a special mathematical tool would...... be beneficial. In this paper, the authors introduce a new decision making tool for resin selection based on significant attributes. This article provides a broad overview of suitable thermoplastic material systems for vacuum infusion process available in today’s market. An illustrative example—resin selection...

  20. Applications of Blue Light-curing Acrylic Resin to Forensic Sample Preparation and Microtomy.

    Science.gov (United States)

    Groves, Ethan; Palenik, Christopher S

    2016-03-01

    This study discusses the results of an evaluation of a one-part blue light-curing acrylic resin for embedding trace evidence prior to the preparation of thin sections with a microtome. Through a comparison to several epoxy resins, the physical properties relevant to both trace evidence examination and analytical microscopy in general, including as viscosity, clarity, color, hardness, and cure speed, were explored. Finally, thin sections from paint samples embedded in this acrylic resin were evaluated to determine if, through smearing or impregnation, the resin contributed to the infrared spectra. The results of this study show that blue light-curing acrylic resins provide the desired properties of an embedding medium, generate high-quality thin sections, and can significantly simplify the preparation of paint chips, fibers and a multitude of other types of microscopic samples in the forensic trace evidence laboratory. © 2015 American Academy of Forensic Sciences.

  1. Drift Degradation Analysis

    International Nuclear Information System (INIS)

    D. Kicker

    2004-01-01

    code, which determines structurally controlled key-block failure, is not applicable for stress-controlled failure in the lithophysal units. To address these limitations, additional numerical codes have been included that can explicitly apply seismic and thermal loads, providing significant improvements to the analysis of drift degradation and extending the validity of drift degradation models

  2. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. Kicker

    2004-09-16

    stress. (3) The DRKBA code, which determines structurally controlled key-block failure, is not applicable for stress-controlled failure in the lithophysal units. To address these limitations, additional numerical codes have been included that can explicitly apply seismic and thermal loads, providing significant improvements to the analysis of drift degradation and extending the validity of drift degradation models.

  3. Effect of adhesive resin cements on bond strength of ceramic core materials to dentin.

    Science.gov (United States)

    Gundogdu, M; Aladag, L I

    2018-03-01

    The aim of the present study was to evaluate the effects of self-etch and self-adhesive resin cements on the shear bond strength of ceramic core materials bonded to dentin. Extracted, caries-free, human central maxillary incisor teeth were selected, and the vestibule surfaces were cut flat to obtain dentin surfaces. Ceramic core materials (IPS e.max Press and Prettau Zirconia) were luted to the dentin surfaces using three self-etch adhesive systems (Duo-Link, Panavia F 2.0, and RelyX Ultimate Clicker) and two self-adhesive resin systems (RelyX U200 Automix and Maxcem Elite). A shear bond strength test was performed using a universal testing machine. Failure modes were observed under a stereomicroscope, and bonding interfaces between the adhesive resin cements and the teeth were evaluated with a scanning electron microscope. Data were analyzed with Student's t-test and one-way analysis of variance followed by Tukey's test (α = 0.05). The type of adhesive resin cement significantly affected the shear bond strengths of ceramic core materials bonded to dentin (P materials when the specimens were luted with self-adhesive resin cements (P resin cements exhibited better shear bond strength than the self-adhesive resin cements, except for Panavia cement in the IPS e.max Press group. However, shear bond strengths of the self-adhesive resin cements were dependent on the nature of the ceramic core materials.

  4. Mechanical and antibacterial properties of benzothiazole-based dental resin materials.

    Science.gov (United States)

    Zhu, Wenbin; Lao, Chonghui; Luo, Shuzhen; Liu, Fang; Huang, Qiting; He, Jingwei; Lin, Zhengmei

    2018-04-01

    A synthesized benzothiazole containing mono-methacrylate monomer BTTMA was incorporated into Bis-GMA/TEGDMA dental resin system with a series of mass concentration from 5 to 30 wt.% as an antibacterial agent. The influence of BTTMA on physicochemical properties of dental resin system, such as double bond conversion (DC), volumetric shrinkage (VS), flexural strength (FS) and modulus (FM), water sorption (WS) and solubility (SL) were investigated. Direct contact testing and agar diffusion testing were used to evaluate the antibacterial activity of BTTMA containing dental resin. The results showed that BTTMA could endow dental resin with significant antibacterial activity when its concentration reached a certain amount (20 wt.%), and the antibacterial activity of BTTMA containing dental resin was mainly attributed to the immobilized BTTMA instead of the unreacted leachable BTTMA. BTTMA had no negative effect on physicochemical properties of dental resin, and even some BTTMA containing dental resins had advantages like higher DC, lower VS and WS when compared with control resin. Therefore, BTTMA could be considered as a suitable antibacterial agent in dental material, but much more researches concerned about biocompatibility should be done in future to prove whether it could be applied in clinic.

  5. Power density of various light curing units through resin inlays with modified layer thickness

    Science.gov (United States)

    Hong, Sung-Ok; Oh, Yonghui; Min, Jeong-Bum; Kim, Jin-Woo; Lee, Bin-Na; Hwang, Yun-Chan; Hwang, In-Nam; Oh, Won-Mann

    2012-01-01

    Objectives The purpose of this study was to enhance curing light penetration through resin inlays by modifying the thicknesses of the dentin, enamel, and translucent layers. Materials and Methods To investigate the layer dominantly affecting the power density of light curing units, resin wafers of each layer with 0.5 mm thickness were prepared and power density through resin wafers was measured with a dental radiometer (Cure Rite, Kerr). The dentin layer, which had the dominant effect on power density reduction, was decreased in thickness from 0.5 to 0.1 mm while thickness of the enamel layer was kept unchanged at 0.5 mm and thickness of the translucent layer was increased from 0.5 to 0.9 mm and vice versa, in order to maintain the total thickness of 1.5 mm of the resin inlay. Power density of various light curing units through resin inlays was measured. Results Power density measured through 0.5 mm resin wafers decreased more significantly with the dentin layer than with the enamel and translucent layers (p inlays increased when the dentin layer thickness was reduced and the enamel or translucent layer thickness was increased. The highest power density was recorded with dentin layer thickness of 0.1 mm and increased translucent layer thickness in all light curing units. Conclusions To enhance the power density through resin inlays, reducing the dentin layer thickness and increasing the translucent layer thickness would be recommendable when fabricating resin inlays. PMID:23431061

  6. Modeling and mechanical performance of carbon nanotube/epoxy resin composites

    International Nuclear Information System (INIS)

    Srivastava, Vijay Kumar

    2012-01-01

    Highlights: ► The MWCNT fillers are uniformly dispersed in the epoxy resin, which improved the mechanical properties of epoxy resin. ► Modified Halpin–Tsai model is useful to calculate the Young’s modulus of MWCNT/epoxy resin composite. ► The experimental moduli are within the variation of 27% with the theoretical values. -- Abstract: The effect of multi-walled carbon nanotube (MWCNT) addition on mechanical properties of epoxy resin was investigated to obtain the tensile strength, compressive strength and Young’s modulus from load versus displacement graphs. The result shows that the tensile strength, compressive strength and Young’s modulus of epoxy resin were increased with the addition of MWCNT fillers. The significant improvements in tensile strength, compressive strength and Young’s modulus were obtained due to the excellent dispersion of MWCNT fillers in the epoxy resin. The dispersion of MWCNT fillers in epoxy resin was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Also, Halpin–Tsai model was modified by considering the average diameter of internal/external of multi-walled nanotube and orientation factor (α) to calculate the Young’s modulus of multi-walled carbon nanotubes (MWCNTs)/epoxy resin composite. There was a good correlation between the experimentally obtained Young’s modulus and modified Halpin–Tsai model.

  7. Cross-Sectional Study of Respiratory Symptoms, Spirometry, and Immunologic Sensitivity in Epoxy Resin Workers.

    Science.gov (United States)

    Hines, Stella E; Barker, Elizabeth A; Robinson, Maura; Knight, Vijaya; Gaitens, Joanna; Sills, Michael; Duvall, Kirby; Rose, Cecile S

    2015-12-01

    An epoxy resin worker developed hypersensitivity pneumonitis requiring lung transplantation and had an abnormal blood lymphocyte proliferation test (LPT) to an epoxy hardener. We assessed the prevalence of symptoms, abnormal spirometry, and abnormal epoxy resin LPT results in epoxy resin workers compared to unexposed workers. Participants completed questionnaires and underwent spirometry. We collected blood for epoxy resin LPT and calculated stimulation indices for five epoxy resin products. We compared 38 exposed to 32 unexposed workers. Higher exposed workers were more likely to report cough (OR 10.86, [1.23-infinity], p = 0.030) or wheeze (OR 4.44, [1.00-22.25], p = 0.049) than unexposed workers, even controlling for smoking. Higher exposed workers were more likely to have abnormal FEV1 than unexposed workers (OR 10.51, [0.86-589.9], p = 0.071), although not statistically significant when adjusted for smoking. There were no differences in proportion of abnormal epoxy resin system LPTs between exposed and unexposed workers. In summary, workers exposed to epoxy resin system chemicals were more likely to report respiratory symptoms and have abnormal FEV1 than unexposed workers. Use of epoxy resin LPT was not helpful as a biomarker of exposure and sensitization. © 2015 Wiley Periodicals, Inc.

  8. Cross‐Sectional Study of Respiratory Symptoms, Spirometry, and Immunologic Sensitivity in Epoxy Resin Workers

    Science.gov (United States)

    Barker, Elizabeth A.; Robinson, Maura; Knight, Vijaya; Gaitens, Joanna; Sills, Michael; Duvall, Kirby; Rose, Cecile S.

    2015-01-01

    Abstract Objectives An epoxy resin worker developed hypersensitivity pneumonitis requiring lung transplantation and had an abnormal blood lymphocyte proliferation test (LPT) to an epoxy hardener. We assessed the prevalence of symptoms, abnormal spirometry, and abnormal epoxy resin LPT results in epoxy resin workers compared to unexposed workers. Methods Participants completed questionnaires and underwent spirometry. We collected blood for epoxy resin LPT and calculated stimulation indices for five epoxy resin products. Results We compared 38 exposed to 32 unexposed workers. Higher exposed workers were more likely to report cough (OR 10.86, [1.23‐infinity], p = 0.030) or wheeze (OR 4.44, [1.00‐22.25], p = 0.049) than unexposed workers, even controlling for smoking. Higher exposed workers were more likely to have abnormal FEV1 than unexposed workers (OR 10.51, [0.86‐589.9], p = 0.071), although not statistically significant when adjusted for smoking. There were no differences in proportion of abnormal epoxy resin system LPTs between exposed and unexposed workers. Conclusions In summary, workers exposed to epoxy resin system chemicals were more likely to report respiratory symptoms and have abnormal FEV1 than unexposed workers. Use of epoxy resin LPT was not helpful as a biomarker of exposure and sensitization. PMID:26553118

  9. Isolation and Identification of Phenol Degrader Bacteria from Sirjan Golgohar Mine Effluent

    Directory of Open Access Journals (Sweden)

    Mehdi Hassanshhian

    2016-03-01

    Full Text Available Phenol and phenolic compounds are highly toxic substances that are found as monoaromatic compounds in various industrial effluents from oil refineries, petrochemical plants, (coal mines, and phenol resin plants. Their discharge into the environment, especially in water resources, causes serious toxicity. Traditionally, physicochemical methods have been used for the removal of phenol and phenolic compounds. Nowadays, bioremediation is known to be the best method for phenol removal from wastewater. The objective of the present study was twofold: isolation and identification of phenol degrading bacteria in the effluent from Golgohar Mine in Sirjan. For this purpose, samples were collected from different sections at Golgohar Mine and its effluent. Phenol degrading bacteria were isolated via enrichment of the samples in the Bushnell Hass medium with phenol used as the only source of carbon and energy. The predominant phenol degrader bacteria were selected by measuring turbidity at 600 nm. The bacteria were subsequently identified by amplification of 16S rRNA with specific primers and PCR sequencing. In this study, 17 strains of phenol degrader bacteria were isolated in soil and wastewater samples collected from different zones of the mine. Screening methods confirmed that 4 strains exhibit a better capability for phenol degradation as evidenced by their capability to degrade 0.4 g/l of phenol. Molecular identification showed that these bacteria belong to the species Pesudomonas sp, Nitrratireductor sp., and Salegentibacter sp. The results also show that the effluent from Golgohar Mine in Sirjan contains many phenol degrading bacteria. The use of these bacteria in the treatment process may lead to a significant reduction in phenol pollution in the mineral effluent.

  10. Dimensional stability and dehydration of a thermoplastic polycarbonate-based and two PMMA-based denture resins.

    Science.gov (United States)

    Pronych, G J; Sutow, E J; Sykora, O

    2003-12-01

    This study compared the dimensional stability and dehydration of a thermoplastic polycarbonate denture base resin with two conventional polymethyl methacrylate denture base resins. Maxillary complete dentures were fabricated from the three denture materials and the accuracy of fit along the posterior palatal border of the cast used in processing was measured. Measurements were conducted at five palatal locations immediately after processing and at 7 and 30 days during immersion in water (23 degrees C) and at 7 and 30 days during dehydration (23 degrees C, 65-75% relative humidity). Percentage mass loss during dehydration was determined with an electronic balance. The thermoplastic material was separately compared with each of the conventional resins using a modified Welch two-sample t-test, with a Bonferroni correction for P values. For mean palatal dimensional change, the thermoplastic resin was generally not statistically different from the conventional resins after processing and during immersion (P > or = 0.06), but was generally less than the conventional resins during dehydration (P thermoplastic resin consistently showed much smaller, statistically significant values compared with the conventional resins (P thermoplastic resin should show dimensional changes in service comparable with the conventional resins, but less dimensional change caused by dehydration.

  11. Antibacterial activity of a modified unfilled resin containing a novel polymerizable quaternary ammonium salt MAE-HB.

    Science.gov (United States)

    Huang, Li; Yu, Fan; Sun, Xiang; Dong, Yan; Lin, Ping-Ting; Yu, Hao-Han; Xiao, Yu-Hong; Chai, Zhi-Guo; Xing, Xiao-Dong; Chen, Ji-Hua

    2016-09-23

    Resins with strong and long-lasting antibacterial properties are critical for the prevention of secondary dental caries. In this study, we evaluated the antibacterial effect and the underlying mechanism of action of an unfilled resin incorporating 2-methacryloxylethyl hexadecyl methyl ammonium bromide (MAE-HB) against Streptococcus mutans UA159 (S. mutans UA159). MAE-HB was added into unfilled resin at 10 mass%, and unfilled resin without MAE-HB served as the control. Bacterial growth was inhibited on 10%-MAE-HB unfilled resin compared with the control at 1 d, 7 d, 30 d, or 180 d (P  0.05). No significant differences in the antibacterial activities of eluents from control versus 10%-MAE-HB unfilled resins were observed at any time point (P > 0.05). The number of bacteria attached to 10%-MAE-HB unfilled resin was considerably lower than that to control. Fe-SEM and CLSM showed that 10%-MAE-HB unfilled resin disturbed the integrity of bacterial cells. Expression of the bacterial glucosyltransferases, gtfB and gtfC, was lower on 10%-MAE-HB unfilled resin compared to that on control (P HB confers unfilled resin with strong and long-lasting antibacterial effects against S. mutans.

  12. Adsorption of heavy metal ions and azo dyes by crosslinked nanochelating resins based on poly(methylmethacrylate-co-maleic anhydride

    Directory of Open Access Journals (Sweden)

    M. Ghaemy

    2014-03-01

    Full Text Available Chelating resins are suitable materials for the removal of heavy metals in water treatments. A copolymer, Poly(MMA-co-MA, was synthesized by radical polymerization of maleic anhydride (MA and methyl methacrylate (MMA, characterized and transformed into multifunctional nanochelating resin beads (80–150 nm via hydrolysis, grafting and crosslink reactions. The resin beads were characterized by swelling studies, field emission scanning electron microscopy (FESEM and Fourier transform infrared spectroscopy (FTIR. The main purpose of this work was to determine the adsorption capacity of the prepared resins (swelling ratio ~55% towards metal ions such as Hg2+, Cd2+, Cu2+ from water at three different pH values (3, 6 and 9. Variations in pH and types of metal ions have not significantly affected the chelation capacity of these resins. The maximum chelation capacity of one of the prepared resin beads (Co-g-AP3 for Hg2+ was 63, 85.8 and 71.14 mg/g at pH 3, 6 and 9, respectively. Approximately 96% of the metal ions could be desorbed from the resin. Adsorption capacity of these resins towards three commercial synthetic azo dyes was also investigated. The maximum adsorption of dye AY42 was 91% for the resin Co-g-AP3 at room temperature. This insures the applicability of the synthesized resins for industrial applications.

  13. Comparison of Shear Bond Strengths of Conventional Resin Cement and Self-adhesive Resin Cement bonded to Lithium Disilicate: An in vitro Study.

    Science.gov (United States)

    Roy, Anip K; Mohan, Dennis; Sunith, M; Mandokar, Rashmi B; Suprasidh, S; Rajan, Soumya

    2017-10-01

    The aim of this study is to compare the shear bond strengths of conventional resin cement and self-adhesive resin cement bonded to lithium disilicate. A total of 40 extracted human molar teeth were mounted in self-cure acrylic resin. Teeth were prepared to obtain flat occlusal surface. About 40 lithium disilicate specimens of dimension-10 mm in diameter and thickness of 2 mm-were fabricated using lost wax technique. The samples were divided into four groups: Groups I, II, III, and IV (n = 10). The specimens were surface treated with Monobond S silane coupling agent. Self-etching primer and bonding agent were applied on the bonding surface of the teeth in groups I and III. The specimens were bonded to the primed teeth with the Multilink N resin cement and subjected to the universal testing machine. The specimens were light-cured. Specimens in groups II and IV were luted to teeth using self-adhesive cement RelyX U100. The same force was applied over the specimen as mentioned above. Excess cement was removed, and light curing was done. The specimens in groups III and IV were subjected to thermocycling for 10,000 cycles at temperatures altering between 5°C and 55°C. The shear bond strengths of conventional resin cement and self-adhesive resin cement with lithium disilicate were tested before and after thermocycling. Results indicated that thermocycling has no significant effect on the bond strengths of conventional or self-adhesive resin cement. However, from the study, it is seen that conventional resin cement had a higher shear bond strength value than the self-adhesive resin cement. There was a significant difference between the average shear bond strength values of conventional resin cement (Multilink N) and self-adhesive resin cement (RelyX U100) when bonded to lithium disilicate disks, and thermocycling had no significant effect on the bond strength of conventional or self-adhesive resin cements. Among all-ceramic systems available, lithium disilicate materials

  14. SEM/XPS analysis of fractured adhesively bonded graphite fibre surface resin-rich/graphite fibre composites

    Science.gov (United States)

    Devilbiss, T. A.; Wightman, J. P.; Progar, D. J.

    1988-01-01

    Samples of graphite fiber-reinforced polyimide were fabricated allowing the resin to accumulate at the composite surface. These surface resin-rich composites were then bonded together and tested for lap shear strength both before and after thermal aging. Lap shear strength did not appear to show a significant improvement over that previously recorded for resin-poor samples and was shown to decrease with increasing aging time and temperature.

  15. Improved thermal stability of methylsilicone resins by compositing with N-doped graphene oxide/Co{sub 3}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Bo, E-mail: jiangbo5981@hit.edu.cn; Zhao, Liwei [Harbin Institute of Technology, Polymer Materials and Engineering Department (China); Guo, Jiang; Yan, Xingru; Ding, Daowei [University of Tennessee, Integrated Composites Laboratory (ICL) Department of Chemical and Biomolecular Engineering (United States); Zhu, Changcheng; Huang, Yudong [Harbin Institute of Technology, Polymer Materials and Engineering Department (China); Guo, Zhanhu, E-mail: zguo10@utk.edu [University of Tennessee, Integrated Composites Laboratory (ICL) Department of Chemical and Biomolecular Engineering (United States)

    2016-06-15

    Nanoparticles play important roles in enhancing the thermal-resistance of hosting polymer resins. Despite tremendous efforts, developing thermally stable methylsilicone resin at high temperatures is still a challenge. Herein, we report a strategy to increase the activation energy to slow down the decomposition/degradation of methylsilicone resin using synergistic effects between the Co{sub 3}O{sub 4} nanoparticles and the nitrogen doped graphene oxide. The N-doped graphene oxides composited with Co{sub 3}O{sub 4} nanoparticles were prepared by hydrolysis of cobalt nitrate hexahydrate in the presence of graphene oxide and were incorporated into the methylsilicone resin. Two-stage decompositions were observed, i.e., 200–300 and 400–500 °C. The activation energy for the low temperature region was enhanced by 47.117 kJ/mol (vs. 57.76 kJ/mol for pure resin). The enhanced thermal stability was due to the fact that the nanofillers prevented the silicone hydroxyl chain ends ‘‘biting’’ to delay the degradation. The activation energy for high-temperature region was enhanced by 11.585 kJ/mol (vs. 171.95 kJ/mol for pure resin). The nanofillers formed a protective layer to isolate oxygen from the hosting resin. The mechanism for the enhanced thermal stability through prohibited degradation with synergism of these nitrogen-doped graphene oxide nanocomposites was proposed as well.Graphical Abstract.

  16. Investigation of the cytotoxicity of thermoplastic denture base resins

    Science.gov (United States)

    Jun, Soo-Kyung; Kim, Si-Chul; Okubo, Chikahiro

    2017-01-01

    PURPOSE The purpose of this study was to investigate the in vitro cytotoxicity of thermoplastic denture base resins and to identify the possible adverse effects of these resins on oral keratinocytes in response to hot water/food intake. MATERIALS AND METHODS Six dental thermoplastic resin materials were evaluated: three polyamide materials (Smile tone, ST; Valplast, VP; and Luciton FRS, LF), two acrylic materials (Acrytone, AT; and Acryshot, AS), and one polypropylene resin material (Unigum, UG). One heat-polymerized acrylic resin (Vertex RS, RS) was chosen for comparison. After obtaining extracts from specimens of the denture resin materials (Φ=10 mm and d=2 mm) under different extraction conditions (37℃ for 24 hours, 70℃ for 24 hours, and 121℃ for 1 hour), the extracts (50%) or serial dilutions (25%, 12.5%, and 6.25%) in distilled water were co-cultured for 24 hours with immortalized human oral keratinocytes (IHOKs) or mouse fibroblasts (L929s) for the cytotoxicity assay described in ISO 10993. RESULTS Greater than 70% viability was detected under all test conditions. Significantly lower IHOK and L929 viability was detected in the 50% extract from the VP (70℃) and AT (121℃) samples (P<.05), but only L929 showed reduced viability in the 50% and 25% extract from LF (37℃) (P<.05). CONCLUSION Extracts obtained from six materials under different extraction conditions (37℃, 70℃, and 121℃) did not exhibit severe cytotoxicity (less than 70% viability), although their potential risk to oral mucosa at high temperatures should not be ignored. PMID:29279765

  17. Influence of different ceramics on resin cement Knoop Hardness Number.

    Science.gov (United States)

    Borges, Gilberto A; Agarwal, Parul; Miranzi, Benito A S; Platt, Jeffrey A; Valentino, Thiago Assunção; dos Santos, Paulo Henrique

    2008-01-01

    This study evaluated: (1) the effect of different ceramics on light attenuation that could affect microhardness, measured as the Knoop Hardness Number (KHN), of a resin cement immediately and 24 hours after polymerization and (2) the effect of different activation modes (direct light-activation, light activation through ceramics and chemical activation) on the KHN of a resin cement. Resin cement Rely XARC (3M ESPE) specimens 5.0 mm in diameter and 1.0 mm thickwere made in a Teflon mold covered with a polyester film. The cement was directly light activated for 40 seconds with an XL 2500 curing unit (3M ESPE) with 650 mW/cm2, light activated through ceramic discs of Duceram Plus (DeguDent), Cergogold (DeguDent), IPS Empress (Ivoclar), IPS Empress 2 (Ivoclar), Procera (NobelBiocare), In Ceram Alumina (Vita) and Cercon (DeguDent), having a 1.2 mm thickness or chemically activatedwith-out light application. The resin cement specimens were flattened, and KHN wasobtained using an HMV 2 microhardnesstester (Shimadzu) with a load of 50 g applied for 15 seconds 100 microm from the irradiated surface immediately and after storage at 37 degrees C for 24 hours. Ten measurements were made for each specimen, with three specimens for each group at each time. The data were submitted to ANOVA and Tukey's test (p = 0.05). The KHN of the resin cement was not only affected by the mode of activation, but also by the post-activation testing time. The mean KHN of the resin cementfor chemical activation and through all ceramics showed statistically significant lower values compared to direct activation immediately and at 24 hours. The KHN for 24 hourspost-activation was always superior to the immediate post-activation test except with direct activation. The most opaque ceramics resulted in the lowest KHN values.

  18. Fatigue Resistance of CAD/CAM Resin Composite Molar Crowns

    Science.gov (United States)

    Shembish, Fatma A.; Tong, Hui; Kaizer, Marina; Janal, Malvin N.; Thompson, Van P.; Opdam, Niek J.; Zhang, Yu

    2016-01-01

    Objective To demonstrate the fatigue behavior of CAD/CAM resin composite molar crowns using a mouth-motion step-stress fatigue test. Monolithic leucite-reinforced glass-ceramic crowns were used as a reference. Methods Fully anatomically shaped monolithic resin composite molar crowns (Lava Ultimate, n = 24) and leucite reinforced glass-ceramic crowns (IPS Empress CAD, n = 24) were fabricated using CAD/CAM systems. Crowns were cemented on aged dentin-like resin composite tooth replicas (Filtek Z100) with resin-based cements (RelyX Ultimate for Lava Ultimate or Multilink Automix for IPS Empress). Three step-stress profiles (aggressive, moderate and mild) were employed for the accelerated sliding-contact mouth-motion fatigue test. Twenty one crowns from each group were randomly distributed among these three profiles (1:2:4). Failure was designated as chip-off or bulk fracture. Optical and electronic microscopes were used to examine the occlusal surface and subsurface damages, as well as the material microstructures. Results The resin composite crowns showed only minor occlusal damage during mouth-motion step-stress fatigue loading up to 1700 N. Cross-sectional views revealed contact-induced cone cracks in all specimens, and flexural radial cracks in 2 crowns. Both cone and radial cracks were relatively small compared to the crown thickness. Extending these cracks to the threshold for catastrophic failure would require much higher indentation loads or more loading cycles. In contrast, all of the glass-ceramic crowns fractured, starting at loads of approximately 450 N. Significance Monolithic CAD/CAM resin composite crowns endure, with only superficial damage, fatigue loads 3 – 4 times higher than those causing catastrophic failure in glass-ceramic CAD crowns. PMID:26777092

  19. Separation and recovery of nucleic acids with improved biological activity by acid-degradable polyacrylamide gel electrophoresis.

    Science.gov (United States)

    Kim, Yoon Kyung; Kwon, Young Jik

    2010-05-01

    One of the fundamental challenges in studying biomacromolecules (e.g. nucleic acids and proteins) and their complexes in a biological system is isolating them in their structurally and functionally intact forms. Electrophoresis offers convenient and efficient separation and analysis of biomacromolecules but recovery of separated biomacromolecules is a significant challenge. In this study, DNAs of various sizes were separated by electrophoresis in an acid-degradable polyacrylamide gel. Almost 100% of the nucleic acids were recovered after the identified gel bands were hydrolyzed under a mildly acidic condition and purified using anion exchange resin. Further concentration by centrifugal filtration and a second purification using ion exchange column chromatography yielded 44-84% of DNA. The second conventional (non-degradable) gel electrophoresis confirmed that the nucleic acids recovered from acid-degradable gel bands preserved their electrophoretic properties through acidic gel hydrolysis, purification, and concentration processes. The plasmid DNA recovered from acid-degradable gel transfected cells significantly more efficiently than the starting plasmid DNA (i.e. improved biological activity via acid-degradable PAGE). Separation of other types of nucleic acids such as small interfering RNA using this convenient and efficient technique was also demonstrated.

  20. Effect of resin shades on opacity of ceramic veneers and polymerization efficiency through ceramics.

    Science.gov (United States)

    Öztürk, Elif; Chiang, Yu-Chih; Coşgun, Erdal; Bolay, Şükran; Hickel, Reinhard; Ilie, Nicoleta

    2013-11-01

    The aim of this study was to assess the effect of different resin cement shades on the opacity and color difference of ceramics and to determine the polymerization efficiency of the resin cement at different shades after curing through ceramics. Two different ceramics (IPS e.max Press and IPS Empress(®)CAD, Ivoclar Vivadent) were used for this study. A light-cured veneer luting resin (Variolink Veneer, Ivoclar Vivadent) in four different shades of HV+1, HV+3, LV-1, and LV-3 was used for the colorimetric measurements. The color and spectral reflectance of the ceramics were measured according to the CIELab color scale relative to the standard illuminant D65 on a reflection spectrophotometer (ColorEye7000A, USA). Color differences (ΔE values) and the contrast ratios (CR) of the different groups of samples were calculated. In order to analyse the polymerization efficiency of the resin cements, the micromechanical properties of the resins were measured with an automatic microhardness indenter (Fisherscope H100C, Germany). The results were analysed using one-way ANOVA and Tukey's HSD post hoc tests (SPSS 18.0). The one-way ANOVA test showed that the values of ΔE and CR of the different specimen groups were significantly different (p<0.05). Group 1 (20.7 ± 0.5) (IPS-CAD without resin cement) exhibited the highest and group 10 (14.8 ± 0.5) (e.max:HV+3) exhibited the lowest ΔE value. Significant differences in the micromechanical properties were identified among the tested resin cements in different shades (p<0.05). Resin cement shade is an important factor for the opacity of a restoration. Furthermore, the resin shade affects the micromechanical properties of the underlying resin cement. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Two-body wear rate of CAD/CAM resin blocks and their enamel antagonists.

    Science.gov (United States)

    Stawarczyk, Bogna; Özcan, Mutlu; Trottmann, Albert; Schmutz, Felix; Roos, Malgorzata; Hämmerle, Christoph

    2013-05-01

    Computer-aided design and computer-aided manufacturing (CAD/CAM) resins exhibit good mechanical properties and can be used as long-term restorations. The wear rate of such resins and their enamel antagonists is unknown. The purpose of this study was to test and compare the 2-body wear rate of CAD/CAM resin blocks. Wear specimens (N=42, n=6) were made from 5 CAD/CAM resins: ZENO PMMA (ZP), artBloc Temp (AT), Telio CAD (TC), Blanc High-class (HC), CAD-Temp (CT); 1 manually polymerized resin: Integral esthetic press (negative control group, IEP); and 1 glass-ceramic: VITA Mark II (positive control group, VM2). The specimens for the wear resistance were aged in a thermomechanical loading machine (49 N, 1.67 Hz, 5/50°C) with human enamel antagonists. The material loss of all specimens before, during, and after aging was evaluated with a 3DS profilometer. The measured material loss data of all tested groups were statistically evaluated with linear mixed model analysis (a=.05). Manually polymerized resin showed significantly higher material wear (PCAD/CAM resins ZP, AT, HC, CT, and IES. CAD/CAM resin TC was not significantly different from the positive control group. Glass-ceramic showed the highest enamel wear values (PCAD/CAM resins showed lower wear rates than those conventionally polymerized. Only one CAD/CAM resin, TC, presented material wear values comparable with glass-ceramic. The tested glass-ceramic developed cracks in the enamel antagonist and showed the highest enamel wear values of all other tested groups. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  2. Foam, Foam-resin composite and method of making a foam-resin composite

    Science.gov (United States)

    Cranston, John A. (Inventor); MacArthur, Doug E. (Inventor)

    1995-01-01

    This invention relates to a foam, a foam-resin composite and a method of making foam-resin composites. The foam set forth in this invention comprises a urethane modified polyisocyanurate derived from an aromatic amino polyol and a polyether polyol. In addition to the polyisocyanurate foam, the composite of this invention further contains a resin layer, wherein the resin may be epoxy, bismaleimide, or phenolic resin. Such resins generally require cure or post-cure temperatures of at least 350.degree. F.

  3. Properties of discontinuous S2-glass fiber-particulate-reinforced resin composites with two different fiber length distributions.

    Science.gov (United States)

    Huang, Qiting; Garoushi, Sufyan; Lin, Zhengmei; He, Jingwei; Qin, Wei; Liu, Fang; Vallittu, Pekka Kalevi; Lassila, Lippo Veli Juhana

    2017-10-01

    To investigate the reinforcing efficiency and light curing properties of discontinuous S2-glass fiber-particulate reinforced resin composite and to examine length distribution of discontinuous S2-glass fibers after a mixing process into resin composite. Experimental S2-glass fiber-particulate reinforced resin composites were prepared by mixing 10wt% of discontinuous S2-glass fibers, which had been manually cut into two different lengths (1.5 and 3.0mm), with various weight ratios of dimethacrylate based resin matrix and silaned BaAlSiO 2 filler particulates. The resin composite made with 25wt% of UDMA/SR833s resin system and 75wt% of silaned BaAlSiO 2 filler particulates was used as control composite which had similar composition as the commonly used resin composites. Flexural strength (FS), flexural modulus (FM) and work of fracture (WOF) were measured. Fractured specimens were observed by scanning electron microscopy. Double bond conversion (DC) and fiber length distribution were also studied. Reinforcement of resin composites with discontinuous S2-glass fibers can significantly increase the FS, FM and WOF of resin composites over the control. The fibers from the mixed resin composites showed great variation in final fiber length. The mean aspect ratio of experimental composites containing 62.5wt% of particulate fillers and 10wt% of 1.5 or 3.0mm cutting S2-glass fibers was 70 and 132, respectively. No difference was found in DC between resin composites containing S2-glass fibers with two different cutting lengths. Discontinuous S2-glass fibers can effectively reinforce the particulate-filled resin composite and thus may be potential to manufacture resin composites for high-stress bearing application. Copyright © 2017. Published by Elsevier Ltd.

  4. Degradation free epoxy impregnation of REBCO coils and cables

    International Nuclear Information System (INIS)

    Barth, C; Bagrets, N; Weiss, K-P; Bayer, C M; Bast, T

    2013-01-01

    In applications utilizing high-temperature superconductors (HTS) under high mechanical loads as high-field magnets or rotors of generators and motors, the rare-earth–barium–copper-oxide (REBCO) tapes have to be stabilized mechanically. This is achieved using support structures of structural materials and filling the voids in the support through the impregnation of the tapes. The impregnation prevents movement of the tapes and distributes mechanical loads evenly. With high mechanical strengths and low sensitivities to rapid temperature changes, epoxy resins are desired materials for the impregnation of superconductor tapes. However, a strong decrease of the current-carrying capabilities was observed in previous epoxy-impregnated REBCO coils. In this work the thermal expansion mismatches between epoxy resins and REBCO tapes are identified as the cause of these degradations. Fillers are used to reduce the thermal expansions of glues and resins. Mixtures with varying filler contents are analyzed systematically. Their thermal expansions and the corresponding degradations of short REBCO tape samples are measured. A mixture of epoxy resin and filler is found which allows degradation-free impregnation of REBCO tapes. This mixture is validated on a 1.2 m long 15 × 5 Roebel-assembled-coated-conductor (RACC) cable from Industrial Research Limited (IRL). (paper)

  5. Ion Exchange Testing with SRF Resin FY2012

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Renee L.; Rinehart, Donald E.; Peterson, Reid A.

    2013-06-11

    Ion exchange using spherical resorcinol-formaldehyde (SRF) resin has been selected by the U.S. Department of Energy’s Office of River Protection (DOE-ORP) for use in the Pretreatment Facility (PTF) of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) and for potential application in at-tank deployment. Numerous studies have shown SRF resin to be effective for removing 137Cs from a wide variety of actual and simulated tank waste supernatants (Adamson et al. 2006; Blanchard et al. 2008; Burgeson et al. 2004; Duignan and Nash 2009; Fiskum et al. 2006a; Fiskum et al. 2006b; Fiskum et al. 2006c; Fiskum et al. 2007; Hassan and Adu-Wusu 2003; King et al. 2004; Nash et al. 2006). Prior work at the Pacific Northwest National Laboratory (PNNL) has focused primarily on the loading behavior for 4 to 6 M Na solutions at 25 to 45°C. Recent proposed changes to the WTP ion exchange process baseline indicate that loading may include a broader range of sodium molarities (0.1 to 8 M) and higher temperatures (50°C) to alleviate post-filtration precipitation issues. This report discusses ion exchange loading kinetics testing activities performed in accordance with Test Plan TP-WTPSP-002, Rev. 3.0 , which was prepared and approved in response to the Test Specification 24590 PTF-TSP-RT-09-002, Rev. 0 (Lehrman 2010) and Test Exception 24590 PTF TEF RT-11-00003, Rev. 0 (Meehan 2011). This testing focused on column tests evaluating the impact of elevated temperature on resin degradation over an extended period of time and batch contacts evaluating the impact on Cs loading over a broad range of sodium concentrations (0.1 to 5 M). These changes may be required to alleviate post-filtration precipitation issues and broaden the data range of SRF resin loading under the conditions expected with the new equipment and process changes.

  6. P134-M Solid Phase Synthesis of C-Terminus Fluorescent Peptide: Comparison of Fmoc-Lys(5-FAM)-Resin and Fmoc-Lys[5-FAM(Trt)]-Resin

    Science.gov (United States)

    Tong, X.; Fu, W.; Sheng, L.

    2007-01-01

    Many FRET (Fluorescent Resonance Energy Transfer) peptides require a C-terminus fluorescent label. In order to facilitate the synthesis of C-terminus fluorescent peptides, we prepared and compared two kinds of resins, Fmoc-Lys(5-FAM)-resin (I) and Fmoc-Lys[5-FAM(trt)]-resin (II).1 Resin (II) has a phenolic hydroxyl group protected with trityl group. The reason for introducing the protecting group was supposedly to prevent the phenolic hydroxyl groups from reacting with the activated amino acids during peptide synthesis. In this report, a fluorescent peptide [EREQTVDLS-VKRPRTGRKKRRQ-RRRK(5-FAM)-NH2] was synthesized using each of these resins. Syntheses were carried out under similar standard conditions. The peptides obtained showed no significant difference in purity. These results showed that resin (I) is also suitable for synthesis of C-terminus fluorescent peptide.

  7. Flexural properties of experimental nanofiber reinforced composite are affected by resin composition and nanofiber/resin ratio.

    Science.gov (United States)

    Vidotti, Hugo A; Manso, Adriana P; Leung, Victor; do Valle, Accácio L; Ko, Frank; Carvalho, Ricardo M

    2015-09-01

    To evaluate the influence of different resin blends concentrations and nanofibers mass ratio on flexural properties of experimental Poliacrylonitrile (PAN) nanofibers reinforced composites. Poliacrylonitrile (PAN) nanofibers mats were produced by electrospinning and characterized by tensile testing and scanning electron microscopy (SEM). Experimental resin-fiber composite beams were manufactured by infiltrating PAN nanofiber mats with varied concentrations of BisGMA-TEGDMA resin blends (BisGMA/TEGDMA: 30/70, 50/50 and 70/30weight%). The mass ratio of fiber to resin varied from 0% to 8%. Beams were cured and stored in water at 37°C. Flexural strength (FS), flexural modulus (FM) and work of fracture (WF) were evaluated by three-point bending test after 24h storage. The tensile properties of the PAN nanofibers indicated an anisotropic behavior being always higher when tested in a direction perpendicular to the rotation of the collector drum. Except for WF, the other flexural properties (FS and FM) were always higher as the ratio of BisGMA to TEGDMA increased in the neat resin beams. The addition of different ratios of PAN fibers did not affect FS and FM of the composite beams as compared to neat resin beams (p>0.05). However, the addition of fibers significantly increased the WF of the composite beams, and this was more evident for the blends with higher TEGDMA ratios (presin blends did not negatively affect the properties of the composite and resulted in an increase in toughness that is a desirable property for a candidate material for prosthodontics application. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. Synthesis of Hydrophobic, Crosslinkable Resins.

    Science.gov (United States)

    1984-12-01

    Bismaleimides have also been crosslinked with radical initiators to produce brittle networks [4].If a damine is added, chain extension and radical crosslinkinq...are produced during cure.The company also produced a similar phenylene based resin, with pendant nitrile groups which could be crosslinked without the...benzenes and tetra substituted cyclopentadienones [881. g. Preparation of poly 1,4 phenylene by nickel (0> catalysed electropolymerisation 1891. Cont’d

  9. Single-stage mass spectrometric analyses of resin bead samples

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D. H.; Walker, R. L.; Bertram, L. K.; Carter, J. A.

    1978-10-01

    Plutonium and uranium from dissolver solutions loaded on resin beads can be analyzed on single-stage mass spectrometers with little or no degradation of results provided proper care is exercised with regard to sample handling techniques. Additionally, storage of samples on resin beads is feasible for periods at least as long as six months provided the beads are not exposed to residual HNO/sub 3/ and air; it is probable that beads will retain their integrity much longer than six months when stored under collodion, but as yet no data to support this contention have been collected. Conventional or commercial mass spectrometers can readily be adapted to the resin bead technique by installing a pulse-counting detection system. The cost of such conversion will vary depending on whether or not a data acquisition system will be needed. A reasonable estimate is that the cost will be in the neighborhood of $15,000; this figure includes the price of a multi-channel analyzer to serve as a temporary data storage device, but does not include the cost of a computer. It does not appear that it will be practicable to switch easily back and forth between pulse-counting and current integration modes unless the instrument is provided with a movable Faraday cup. Using the same multiplier in both modes would undoubtedly degrade its performance in each. The requirements of low background counting rates and high gain for pulse counting, and of relatively high signal handling capacity in current integration are mutually incompatible if demanded of the same multiplier.

  10. Shear bond strength evaluation of resin composite to resin-modified glass-ionomer cement using three different resin adhesives vs. glass-ionomer based adhesive

    Directory of Open Access Journals (Sweden)

    Mostafa Sadeghi

    2015-12-01

    Full Text Available Background: The clinical success of sandwich technique depends on the strength of resin-modified glass ionomer cement (RMGIC bonding to both dentin and resin composite. Therefore, the shear bond strength (SBS of resin composite bonded to RMGIC utilizing different resin adhesives versus a GIC-based adhesive was compared. Materials and methods: In this in vitro study, 84 holes (5×2 mm were prepared in acrylic blocks, randomly divided into seven groups (n=12 and filled with RMGIC (Light-Cured Universal Restorative, GC. In the Group I; no adhesive was applied on the RMGIC. In the Group II, non-etched and Group III was etched with phosphoric acid. In groups II and III, after rinsing, etch-and-rinse adhesive (OptiBond Solo Plus; in the Group IV; a two-step self-etch adhesive (OptiBond XTR and in Group V; a one-step self-etch (OptiBond All-in-One were applied on the cement surfaces. Group VI; a GIC-based adhesive (Fuji Bond LC was painted over the cement surface and cured. Group VII; the GIC-based adhesive was brushed over RMGIC followed by the placement of resin composite and co-cured. Afterward; resin composite (Point 4 cylinders were placed on the treated cement surfaces. The specimens were placed in 100% humidity at 37 ± 1°C and thermo cycled. The shear bond test was performed at a cross-head speed of 1 mm/min and calculated in MPa; the specimens were examined to determine mode of failure. The results were analyzed using one-way ANOVA and Tukey test. Results: The maximum (24.62±3.70 MPa and minimum (18.15±3.38 MPa SBS mean values were recorded for OptiBond XTR adhesive and the control group, respectively. The pairwise comparisons showed no significant differences between the groups that bonded with different adhesives. The adhesive failure was the most common failure mode observed. Conclusion: This study suggests that GIC-based adhesive could be applied over RMGIC as co-cure technique for sandwich restorations in lieu of employing the resin

  11. Effects of metal primers on the bonding of an adhesive resin cement to noble metal ceramic alloys after thermal cycling.

    Science.gov (United States)

    Minami, Hiroyuki; Murahara, Sadaaki; Suzuki, Shiro; Tanaka, Takuo

    2011-12-01

    Although the effectiveness of primers for resin bonding to noble alloys has been demonstrated, no effective clinical technique for bonding to noble metal ceramic alloys has been established. The purpose of this study was to evaluate the effects of metal primers on the shear bond strength of an adhesive resin to noble metal ceramic alloys after thermal cycling. Sixty-three disk-shaped specimens (10 × 2.5 mm) were cast from high-gold-content alloys (Super Metal W-85: W85 or IFK88 GR: IFK88), a high-palladium-content alloy (Super Metal N-40: N40), and an Ag-Pd-Cu-Au alloy (Castwell M.C.12: MC12). Smaller-sized disk-shaped specimens (8 × 2.5 mm) were fabricated with MC12. Bonding surfaces were finished with 600-grit SiC-paper and airborne-particle abraded with 50-μm alumina. Pairs of disks were primed (V-Primer: VP; ML Primer: ML; or Metaltite: MT) and bonded with an adhesive resin (Super-Bond C&B). The bond strengths were determined before and after 20,000 and 50,000 thermal cycles (n=7). Data were analyzed by using a 3-way ANOVA and the Bonferroni test (α=.05). Failure modes were determined by optical microscope and SEM observation. Bond strengths to high-gold-content alloys with VP and MT significantly decreased after the thermal cycling (Palloys were not degraded up to 50,000 thermal cycles when primed with ML. None of the primers evaluated was effective for high-palladium-content alloy. Copyright © 2011 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  12. Dynamic thermo-mechanical properties of various flowable resin composites

    Science.gov (United States)

    Balthazard, Rémy; Vincent, Marin; Dahoun, Abdessellam; Mortier, Eric

    2016-01-01

    Background This study compared the storage modulus (E’), the loss modulus (E’’) and the loss tangent (tan δ) of various flowable resin composites. Material and Methods Grandio Flow (GRF), GrandioSo Heavy Flow (GHF), Filtek Supreme XTE (XTE) and Filtek Bulk Fill (BUL) flowable resins and Clinpro Sealant (CLI) ultra-flowable pit and fissure sealant resin were used. 25 samples were tested using a dynamical mechanical thermal analysis system in bending mode. Measurements were taken within a temperature range of 10 to 55°C. The results were statistically analyzed using mixed-effect and repeated-measure analysis of variance followed by paired multiple comparisons. Results For all the materials, the E’ values decrease with temperature, whereas the tan δ values increase. Irrespective of the temperature, GHF and GRF present E’ and E’’ values significantly higher than all the other materials and CLI presents values significantly lower than all the other materials. Observation of the values for all the materials reveals a linear progression of the tan δ values with temperature. Conclusions A variation in temperature within a physiological range generates modifications in mechanical properties without damaging the material, however. Filler content in volume terms appears to be the crucial parameter in the mechanical behavior of tested materials. Key words:Dynamic mechanical thermal analysis, elastic modulus, filler content, flowable resin composites, loss modulus, loss tangent. PMID:27957266

  13. Interactions of self-etch adhesives with resin composites.

    Science.gov (United States)

    Kurokawa, Rie; Finger, Werner J; Hoffmann, Marcus; Endo, Tatsuo; Kanehira, Masafumi; Komatsu, Masashi; Manabe, Atsufumi

    2007-12-01

    Aim of this in vitro study was to investigate the correlation of shear bond strength and marginal cavity adaptation, together with polymerization shrinkage and contraction stress, using the combination of four self-etch adhesives and three resin composites. Interactions were studied between one two-step and three one-step adhesives, and the hybrid-type resin composites, Beautifil (BEU, Shofu) and Venus (VEN, Heraeus), and an experimental nano-hybrid resin composite NEUN (NEU, Heraeus). For all 12 combinations shear bond strengths (SBS) were determined on human dentin. Marginal adaptation (MGW) was assessed in cylindrical butt-joint dentin cavities. Further, polymerization contraction and contraction stress of the resin restoratives were measured. Significant determinants of SBSs on dentin were time of testing (10min or 24h) and adhesives (presin composite used was a highly significant determinant of cavity adaptation. Polymerization shrinkage after 5min was 2.58, 2.74, and 1.53% for BEU, VEN, and NEU, respectively. Polymerization contraction stresses were largest for BEU, less for VEN, and smallest for NEU (presin composites were identified as important determinants of marginal cavity adaptation.

  14. Toothbrushing alters the surface roughness and gloss of composite resin CAD/CAM blocks.

    Science.gov (United States)

    Kamonkhantikul, Krid; Arksornnukit, Mansuang; Lauvahutanon, Sasipin; Takahashi, Hidekazu

    2016-01-01

    This study investigated the surface roughness and gloss of composite resin CAD/CAM blocks after toothbrushing. Five composite resin blocks (Block HC, Cerasmart, Gradia Block, KZR-CAD Hybrid Resin Block, and Lava Ultimate), one hybrid ceramic (Vita Enamic), one feldspar ceramic (Vitablocs Mark II), one PMMA block (Telio CAD), and one conventional composite resin (Filtek Z350 XT) were evaluated. Surface roughness (Ra) and gloss were determined for each group of materials (n=6) after silicon carbide paper (P4000) grinding, 10k, 20k, and 40k toothbrushing cycles. One-way repeated measures ANOVA indicated significant differences in the Ra and gloss of each material except for the Ra of GRA. After 40k toothbrushing cycles, the Ra of BLO and TEL showed significant increases, while CER, KZR, ULT, and Z350 showed significant decreases. GRA, ENA, and VIT maintained their Ra. All of the materials tested, except CER, demonstrated significant decreases in gloss after 40k toothbrushing cycles.

  15. Analysis of atomic oxygen and ultraviolet exposure effects on cycloaliphatic epoxy resins reinforced with octa-functional POSS

    Science.gov (United States)

    Suliga, Agnieszka; Jakubczyk, Ewa M.; Hamerton, Ian; Viquerat, Andrew

    2018-01-01

    In this study, novel nanocomposites were created by incorporation of Silsesquioxane containing eight glycidylether groups (octa-POSS) into a cycloaliphatic epoxy cured by an anhydride. The developed resin system, with different nanoparticle concentrations, was used on the outer layers of an ultra-thin CFRP structure in order to provide better environmental resistance to the environment of low Earth orbit (LEO) which was tested in a ground-simulation facility. The developed resins were subjected to space-like degrading factors and their response to corrosion, radiation and elevated temperatures was monitored by mass loss, together with measuring changes in surface chemistry (ATR-FTIR), functionality development (contact angle measurement and XPS), roughness (scanning laser microscopy) and morphology (SEM). The influence of increasing octa-POSS content on thermo-mechanical properties was measured with DMTA and the strength and modulus of elasticity were determined by flexural test. The addition of octa-POSS in any loading improves the environmental resistance, however, the most significant retention of mass and mechanical and surface properties after space-like exposure was observed in the 20 wt% octa-POSS reinforced cycloaliphatic epoxy. The results presented here may contribute to the development of novel class of nanocomposites which can offer an extended service life in LEO.

  16. Compatibility between dental adhesive systems and dual-polymerizing composite resins.

    Science.gov (United States)

    Michaud, Pierre-Luc; MacKenzie, Alexandra

    2016-10-01

    Information is lacking about incompatibilities between certain types of adhesive systems and dual-polymerizing composite resins, and universal adhesives have yet to be tested with these resins. The purpose of this in vitro study was to investigate the bonding outcome of dual-polymerizing foundation composite resins by using different categories of adhesive solutions and to determine whether incompatibilities were present. One hundred and eighty caries-free, extracted third molar teeth were allocated to 9 groups (n=20), in which 3 different bonding agents (Single Bond Plus [SB]), Scotchbond Multi-purpose [MP], and Scotchbond Universal [SU]) were used to bond 3 different composite resins (CompCore AF [CC], Core Paste XP [CP], and Filtek Supreme Ultra [FS]). After restorations had been fabricated using an Ultradent device, the specimens were stored in water at 37°C for 24 hours. The specimens were tested under shear force at a rate of 0.5 mm/min. The data were analyzed with Kruskal-Wallis tests and post hoc pairwise comparisons (α=.05). All 3 composite resins produced comparable shear bond strengths when used with MP (P=.076). However, when either SB or SU was used, the light-polymerized composite resin (FS) and 1 dual-polymerized foundation composite resin (CC) bonded significantly better than the other dual-polymerized foundation composite resin (CP) (Pcomposite resins can obtain equally good bond strengths as light-polymerizing alternatives. However, not all dual-polymerizing composite resins perform well with all bonding systems; some incompatibilities exist between different products. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  17. Studies on the Conditioning Methods of Spent Tri-butyl Phosphate/Kerosene and its Degradation Product in Different Matrices

    International Nuclear Information System (INIS)

    El-Dessouky, M.I.; El-sourougy, M.R.; Abed El-Aziz, M.M.; Aly, H.F.

    1999-01-01

    The destruction of spent TBP/Kerosene (odourless Kerosene (OK)) with potassium permanganate have been investigated. Comparative studies on the immobilization of spent TBP/Kerosene and its degradation product into different matrices have been carried out. The matrices used include, ordinary Portland cement, silica fume, treated fly ash, epoxy resin and cement mixed with epoxy resin.The different factors affecting solidified waste forms such as, compressive strength, water resistance, thermal stability, chemical resistance, radiological stability and leachability have been investigated. It was found that, epoxy resin and cement mixed with 5,10,20, and 50% of epoxy resin enhance the compressive strength of the solidified waste forms with spent TBP/OK more than that obtained from degradation products. The leaching rates of 152 and 154 Eu and 181 Hf from waste forms containing TBP/OK was found lower than that with degradation product

  18. Studies on the conditioning methods of spent tri-butyl phosphate/kerosene and its degradation product in different matrices

    International Nuclear Information System (INIS)

    El-Dessouky, M.I.; El-Sourougy, M.R.; Abed El-Aziz, M.M.; Aly, H.F.

    2001-01-01

    The destruction of spent TBP/Kerosene (odourless kerosene (OK)) with potassium permanganate has been investigated. Comparative studies on the immobilization of spent TBP/Kerosene and its degradation product into different matrices have been carried out. The matrices used include, ordinary portland cement, silica fume, treated fly ash, epoxy resin and cement mixed with epoxy resin. The different factors affecting solidified waste forms, such as compressive strength, water resistance, thermal stability, chemical resistance, radiological stability and leachability, have been investigated. It was found that epoxy resin and cement mixed with 5, 10, 20, and 50% of epoxy resin enhance the compressive strength of the solidified waste forms with spent TBP/OK more than that obtained from degradation products. The leaching rates of 152,154 Eu and 181 Hf from waste forms containing TBP/OK was found lower than that with degradation product. (author)

  19. Evaluation of adhesion of reline resins to the thermoplastic denture base resin for non-metal clasp denture.

    Science.gov (United States)

    Kim, Ji Hye; Choe, Han Cheol; Son, Mee Kyoung

    2014-01-01

    This study aimed to evaluate the tensile and transverse bond strength of chairside reline resins (Tokuyama Rebase II, Mild Rebaron LC) to a thermoplastic acrylic resin (Acrytone) used for non metal clasp denture. The results were compared with those of a conventional heat polymerized acrylic resin (Paladent 20) and a thermoplastic polyamide resin (Biotone). The failure sites were examined by scanning electron microscopy to evaluate the mode of failure. As results, the bond strength of reline resins to a thermoplastic acrylic resin was similar to the value of a conventional heat polymerized acrylic resin. However, thermoplastic polyamide resin showed the lowest value. The results of this study indicated that a thermoplastic acrylic resin for non metal clasps denture allows chairside reline and repair. It was also found that the light-polymerized reline resin had better bond strength than the autopolymerizing reline resin in relining for a conventional heat polymerized acrylic resin and a thermoplastic acrylic resin.

  20. Synthesis, Chacterization, and Thermal Study of Terpolymeric Resin Derived from m-cresol, Hexamine and Formaldehyde

    Directory of Open Access Journals (Sweden)

    K. M. Khedkar

    2012-01-01

    Full Text Available Terpolymeric resin was prepared from m-cresol (0.1M, hexamine (0.05M and formaldehyde (0.2M by acid catalyzed polycondensation method using 1M HCl in temperature range of 122-130°C.The resin was abbreviated as m-CHF-I. The molecular weight of terpolymer was determined by non-aqueous conductometric titration technique. The structure of resin was determined by its elemental analysis, UV-VIS, IR, and NMR data. The thermokinetic parameters were determined using Freeman-Carroll (FC and Sharp Wentworth (SW method in temperature range (410-485°C.The values of activation energies (Ea, entropy (∆S, and free energies (∆G were in good agreement . The order of degradation reaction determined by FC method was confirmed by SW method.

  1. Solvent purification with high-porosity (macroreticular) ion-exchange resin

    International Nuclear Information System (INIS)

    McKibben, J.M.

    Numerous solvent degradation products exist in all of our process solvents that are not efficiently removed in the routine solvent washing operation. Tests indicate that a relatively new type of resin - variously called high-porosity, macroreticular, or macroporous resin - removes at least some of these persistent chemicals and substantially improves the quality of any TBP process solvent. A plant test is proposed for the purification of the first cycle solvent of the HM process, in which a loop will be installed to draw a small side stream of solvent from the washed solvent hold tank (904), pass it through a 2.7 ft 3 resin column, and return it to the same tank

  2. Flame Retardance and Physical Properties of Novel Cured Blends of Unsaturated Polyester and Furan Resins

    Directory of Open Access Journals (Sweden)

    Baljinder Kaur Kandola

    2015-02-01

    Full Text Available Novel blends of two furan resins with an unsaturated polyester have been prepared and cured by parallel free radical (for the unsaturated polyester and acid-catalysed crosslinking (for the furan resin to give co-cured composite materials. Although these materials have inferior physical properties, such as low Tg and low storage modulus compared with those of unsaturated polyester and furan resins alone, they show markedly improved flame retardance compared with that of the normally highly flammable unsaturated polyester. This increased flame retardance arises from a condensed phase mechanism in which the furanic component forms a semi-protective char, reducing rates of thermal degradation and total heat release and heat of combustion. The blends also burn with reduced smoke output compared with that from unsaturated polyester alone.

  3. γ-Ray irradiation stability and damage mechanism of glycidyl amine epoxy resin

    Energy Technology Data Exchange (ETDEWEB)

    Diao, Feiyu; Zhang, Yan; Liu, Yujian; Fang, Jun [Key Laboratory for Specially Functional Polymers and Related Technology of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Luan, Weilin [Key Laboratory of Pressure and Safety (MOE), School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2016-09-15

    Irradiation stability of triglycidyl-p-aminophenol (TGPAP) epoxy resins was evaluated according to the changes of physico-chemical and mechanical properties under {sup 60}Co γ-ray irradiation with a dose rate of 10 kGy/h. The result shows that with the increase of radiation dose, bending strength, thermal stability, free radical concentration and storage modulus of epoxy resin decrease first, then increase slightly, and decline sharply at the end with a dose of 960 kGy, due to competition effects between radiation-induced degradation and cross-linking reaction. The damage mechanism was derived by analyzing structure and composition change of AFG-90 resins after irradiation via IR and XPS. Irradiation will result in weak bond breaking such as C−C and C−N bond, and new bond forming like C=C and C=O.

  4. Profile of Fluoride Release from a Nanohybrid Composite Resin

    Directory of Open Access Journals (Sweden)

    Raquel Assed Bezerra Silva

    2015-02-01

    Full Text Available The aim of this study was to evaluate in vitro the amount and profile of fluoride release from a fluoride-containing nanohybrid composite resin (Tetric® N-Ceram by direct potentiometry. Thirty specimens (5 mm diameter x 3 mm high; n=10/material were made of Tetric® N-Ceram, Vitremer® resin-modified glass ionomer cement (RMGIC (positive control or Filtek® Z350 nanofill composite resin (negative control. The specimens were stored individually in plastic tubes containing 1 mL of artificial saliva at 37°C, which was daily renewed during 15 days. At each renewal of saliva, the amount of fluoride ions released in the solution was measured using a fluoride ion-selective electrode with ion analyzer, and the values obtained in mV were converted to ppm (µg/mL. Data were analyzed statistically by ANOVA and Tukey’s post-hoc test at a significance level of 5%. The results showed that the resins Tetric® N-Ceram and Filtek® Z350 did not release significant amounts of fluoride during the whole period of evaluation (p>0.05. Only Vitremer® released significant amounts of fluoride ions during the 15 days of the experiment, with greater release in first 2 days (p0.05. In conclusion, the nanohybrid composite resin Tetric® N-Ceram did not present in vitro fluoride-releasing capacity throughout the 15 days of study.

  5. Kekerasan mikro resin komposit packable dan bulkfill dengan kedalaman kavitas berbeda

    Directory of Open Access Journals (Sweden)

    Diatri Nari Ratih

    2017-12-01

    Full Text Available Microhardness of packable and bulkfill composite resin with different cavity depths. Bulkfill composite resin restorations are increasingly popular because the material can be irradiated with a thickness reaching 4 mm, making it easier to apply. The objective of this study was to determine the differences in the microhardness between packable and bulkfill composite resin restorations with a cavity depth of 2 mm and 4 mm. This study was done using 32 Teon molds (5 mm diameter, and grouped randomly into 4 groups in which each consisted of 8 samples. Group 1A, packable composite resin was applied to the mold with a cavity depth of 2 mm. Group 1B, bulkfill composite resin was applied to the mold with a cavity depth of 2 mm. Group 2A, packable composite resin was applied with a depth of 4 mm. Group 2B, bulkfill composite resin was applied with a depth of 4 mm. Each sample was immersed in articial saliva with a pH of 6.8 and stored in an incubator at a temperature of 37°C for 24 hours. The hardness of each sample was tested using Vickers indenter microhardness tester. The data obtained were then analyzed by using two-way ANOVA, followed by Tukey’s test. The results showed that bulkfill composite resin with a cavity depth of 2 mm has the highest average of microhardness (31.09 ± 2.02 VHN, followed by packable composite resin with a depth of 2 mm (17.52 ± 1.25 VHN, bulkfill with a depth of 4 mm (11.97 ± 1.23 VHN and packable with a depth of 4 mm (3.18 ± 0.85 VHN. The two-way ANOVA analysis showed that there are significant differences between the types of composite resin and cavity depths (p < 0.05, and there is interaction between the types of composite resin and cavity depth (p<0.05. In conclusion, the microhardness of packable composite resin is lower than that of bulkfill at a cavity depth of 2 and 4 mm.   ABSTRAK Restorasi resin komposit dengan bulkfill semakin populer karena material tersebut dapat disinar dengan ketebalan sampai 4

  6. Interfacial microscopic examination and chemical analysis of resin-dentin interface of self-adhering flowable resin composite [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Tamer M. Hamdy

    2017-10-01

    Full Text Available Background: The newly introduced self-adhering flowable resin-composites decrease the required time for application by incorporation of an acidic adhesive monomer, thus reducing the number of the steps, but its bonding is still uncertain. The aim of this study was to evaluate the interfacial microscopic examination and chemical analysis at the resin-dentin interface of a self-adhering flowable resin composite (Vertise-Flow versus a total-etch (Te-Econom Plus resin composite, using an etching agent (Eco-Etch gel and  bonding agent (Single Bond Universal. Methods: Sixteen freshly extracted sound human posterior teeth were used. The teeth were randomly divided into two groups: 8 specimens per type of composite. Standard-shaped class V cavities were prepared on the buccal surface. One group was restored by Te-Econom Plus resin composite by total-etch technique using Eco-Etch gel, which was applied to dentine for 15 seconds, followed by rinsing, drying and bonding agent application (Single Bond Universal. The other group restored directly with self-adhering resin composite (Vertise-Flow without application of etch or bond. Curing was done for 20 seconds using a light emitting diode light curing unit. Evaluation of the resin-dentin interface was done microscopically by examination of marginal gap distance in μm using scanning electron microscope (SEM, and chemical analysis of silver particles was observed using SEM with energy-dispersive X-ray spectrometry after 24 hours of specimen storage in ammoniacal silver nitrate. Results: Regarding marginal gap distance (µm and silver atomic % mean values, teeth restored with self-adhering resin composite (Vertise-Flow showed significantly higher mean values than the multi-step etch and rinse resin composite group (5.2 vs 0; 12.2 vs 8.2, respectively. Conclusions: Resin-dentin bonding using total-etch resin composite technique was more effective than self-adhering flowable resin composite (Vertise

  7. Interfacial microscopic examination and chemical analysis of resin-dentin interface of self-adhering flowable resin composite [version 3; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Tamer M. Hamdy

    2017-10-01

    Full Text Available Background: The newly introduced self-adhering flowable resin-composites decrease the required time for application by incorporation of an acidic adhesive monomer, thus reducing the number of steps, but its bonding is still uncertain. The aim of this study was to evaluate the interfacial microscopic examination and chemical analysis at the resin-dentin interface of a self-adhering flowable resin composite (Vertise™Flow Self-Adhering Flowable Composite, Kerr Dental, USA versus a total-etch (Te-Econom Plus resin composite, using an etching agent (Eco-Etch gel and bonding agent (Single Bond Universal. Methods: Sixteen freshly extracted sound human posterior teeth were used. The teeth were randomly divided into two groups: 8 specimens per type of composite. Standard-shaped class V cavities were prepared on the buccal surface. One group was restored by Te-Econom Plus resin composite by total-etch technique using Eco-Etch gel, which was applied to dentine for 15 seconds, followed by rinsing, drying and bonding agent application (Single Bond Universal. The other group restored directly with self-adhering resin composite (Vertise-Flow without application of etch or bond. Curing was done for 20 seconds using a light emitting diode light curing unit. Evaluation of the resin-dentin interface was done microscopically by examination of marginal gap distance in μm using scanning electron microscope (SEM, and chemical analysis of silver particles was observed using SEM with energy-dispersive X-ray spectrometry after 24 hours of specimen storage in ammoniacal silver nitrate. Results: Regarding marginal gap distance (µm and silver atomic % mean values, teeth restored with self-adhering resin composite (Vertise-Flow showed significantly higher mean values than the multi-step etch and rinse resin composite group (5.2 vs 0; 12.2 vs 8.2, respectively. Conclusions: Resin-dentin bonding using total-etch resin composite technique was more effective than self

  8. Resin selection criteria for tough composite structures

    Science.gov (United States)

    Chamis, C. C.; Smith, G. T.

    1983-01-01

    Resin selection criteria are derived using a structured methodology consisting of an upward integrated mechanistic theory and its inverse (top-down structured theory). These criteria are expressed in a "criteria selection space" which are used to identify resin bulk properties for improved composite "toughness". The resin selection criteria correlate with a variety of experimental data including laminate strength, elevated temperature effects and impact resistance.

  9. Solidifying power station resins and sludges

    International Nuclear Information System (INIS)

    Willis, A.S.D.; Haigh, C.P.

    1984-01-01

    Radioactive ion exchange resins and sludges arise at nuclear power stations from various operations associated with effluent treatment and liquid waste management. As the result of an intensive development programme, the Central Electricity Generating Board (CEGB) has designed a process to convert power station resins and sludges into a shielded, packaged solid monolithic form suitable for final disposal. Research and development, the generic CEGB sludge/resin conditioning plant and the CEGB Active Waste Project are described. (U.K.)

  10. Volumetric polymerization shrinkage of contemporary composite resins

    OpenAIRE

    Nagem Filho, Halim; Nagem, Haline Drumond; Francisconi, Paulo Afonso Silveira; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia; Coutinho, Kennedy Queiroz

    2007-01-01

    The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill ...

  11. Porous Ceramic Spheres from Ion Exchange Resin

    Science.gov (United States)

    Dynys, Fred

    2005-01-01

    A commercial cation ion exchange resin, cross-linked polystyrene, has been successfully used as a template to fabricate 20 to 50 micron porous ceramic spheres. Ion exchange resins have dual template capabilities. Pore architecture of the ceramic spheres can be altered by changing the template pattern. Templating can be achieved by utilizing the internal porous structure or the external surface of the resin beads. Synthesis methods and chemical/physical characteristics of the ceramic spheres will be reported.

  12. Bond strength of resin-resin interfaces contaminated with saliva and submitted to different surface treatments

    OpenAIRE

    Furuse, Adilson Yoshio; Cunha, Leonardo Fernandes da; Benetti, Ana Raquel; Mondelli, José

    2007-01-01

    The purpose of this study was to investigate the effect of different surface treatments on shear bond strength of saliva-contaminated resin-resin interfaces. Flat resin surfaces were fabricated. In the control group, no contamination or surface treatment was performed. The resin surfaces of the experimental groups were contaminated with saliva and air-dried, and then submitted to: (G1) rinsing with water and drying; (G2) application of an adhesive system; (G3) rinsing and drying, abrasion wit...

  13. Effects of toothbrush hardness on in vitro wear and roughness of composite resins.

    Science.gov (United States)

    Kyoizumi, Hideaki; Yamada, Junji; Suzuki, Toshimitsu; Kanehira, Masafumi; Finger, Werner J; Sasaki, Keiichi

    2013-11-01

    To investigate and compare the effects of toothbrushes with different hardness on abrasion and surface roughness of composite resins. Toothbrushes (DENT. EX Slimhead II 33, Lion Dental Products Co. Ltd., Tokyo, Japan) marked as soft, medium and hard, were used to brush 10 beam-shaped specimens of each of three composites resins (Venus [VEN], Venus Diamond [VED] and Venus Pearl [VEP]; HeraeusKulzer) with standardized calcium carbonate slurry in a multistation testing machine (2N load, 60 Hz). After each of five cycles with 10k brushing strokes the wear depth and surface roughness of the specimens were determined. After completion of 50k strokes representative samples were inspected by SEM. Data were treated with ANOVA and regression analyses (p composite resins increased linearly with increasing number of brushing cycles (r² > 0.9). Highest wear was recorded for VEN, lowest for VED. Hard brushes produced significantly higher wear on VEN and VEP, whereas no difference in wear by toothbrush type was detected for VED. Significantly highest surface roughness was found on VED specimens (Ra > 1.5 µm), the lowest one on VEN (Ra composite resins produced by toothbrushing with dentifrice depend mainly on the type of restorative resin. Hardness grades of toothbrushes have minor effects only on abrasion and surface roughness of composite resins. No relationship was found between abrasion and surface roughness. The grade of the toothbrush used has minor effect on wear, texture and roughness of the composite resin.

  14. Microstructure and mechanical properties of composite resins subjected to accelerated artificial aging.

    Science.gov (United States)

    dos Reis, Andréa Cândido; de Castro, Denise Tornavoi; Schiavon, Marco Antônio; da Silva, Leandro Jardel; Agnelli, José Augusto Marcondes

    2013-01-01

    The aim of this study was to investigate the influence of accelerated artificial aging (AAA) on the microstructure and mechanical properties of the Filtek Z250, Filtek Supreme, 4 Seasons, Herculite, P60, Tetric Ceram, Charisma and Filtek Z100. composite resins. The composites were characterized by Fourier-transform Infrared spectroscopy (FTIR) and thermal analyses (Differential Scanning Calorimetry - DSC and Thermogravimetry - TG). The microstructure of the materials was examined by scanning electron microscopy. Surface hardness and compressive strength data of the resins were recorded and the mean values were analyzed statistically by ANOVA and Tukey's test (α=0.05). The results showed significant differences among the commercial brands for surface hardness (F=86.74, pcomposite resins. FTIR, DSC and TG analyses showed that resin polymerization was complete, and there were no differences between the spectra and thermal curve profiles of the materials obtained before and after AAA. TG confirmed the absence of volatile compounds and evidenced good thermal stability up to 200 °C, and similar amounts of residues were found in all resins evaluated before and after AAA. The AAA treatment did not significantly affect resin surface. Therefore, regardless of the resin brand, AAA did not influence the microstructure or the mechanical properties.

  15. Microhardness and Penetration of Artificial White Spot Lesions Treated with Resin or Colloidal Silica Infiltration.

    Science.gov (United States)

    Mandava, Jyothi; Reddy, Y Shilpa; Kantheti, Sirisha; Chalasani, Uma; Ravi, Ravi Chandra; Borugadda, Roopesh; Konagala, Ravi Kumar

    2017-04-01

    Infiltration of early enamel lesions by materials having remineralizing capacity seems to improve aesthetics and arrests caries progression. To evaluate and compare the surface microhardness and penetration depth of a low viscosity resin and colloidal silica nanoparticle infiltrates into artificially created white spot lesions. Forty extracted human central incisors were embedded in acrylic resin blocks exposing the labial surfaces of the crowns. The specimens were immersed in demineralizing solution for 96 hours to create white spot lesions on labial surfaces. The samples were then divided into two groups (n=20 each), where in Group 1-resin infiltration (ICON DMG, Hamburg, Germany) and Group 2-colloidal silica infiltration (Arrow Fine chemicals, Rajkot, Gujarat, India) was done. Samples were subjected to vicker's microhardness testing at baseline, after demineralization and after treatment with resin or colloidal silica infiltrates. Then, the crowns were sectioned longitudinally and penetration depth of the infiltrants was measured using confocal laser scanning microscope and compared the readings to lesion depth. All the collected data was subjected to statistical analysis using t-test. Resin infiltration group showed significantly greater increase in microhardness compared to colloidal silica infiltration (p=0.001). The percentage of penetration of the resin group was 67.14% and that of colloidal silica group was 54.53% indicating significant difference between the two. Resin infiltrates performed better in regaining the baseline microhardness and penetrating deep into the porous white spot lesions, when compared to colloidal silica infiltrates.

  16. Adsorption of saponin compound in Carica papaya leaves extract using weakly basic ion exchanger resin

    Science.gov (United States)

    Abidin, Noraziani Zainal; Janam, Anathasia; Zubairi, Saiful Irwan

    2016-11-01

    Adsorption of saponin compound in papaya leaves juice extract using Amberlite® IRA-67 resin was not reported in previous studies. In this research, Amberlite® IRA-67 was used to determine the amount of saponin that can be adsorbed using different weights of dry resin (0.1 g and 0.5 g). Peleg model was used to determine the maximum yield of saponin (43.67 mg) and the exhaustive time (5.7 days) prior to a preliminary resin-saponin adsorption study. After adsorption process, there was no significant difference (p>0.05) in total saponin content (mg) for sample treated with 0.1 g (3.79 ± 0.55 mg) and sample treated with 0.5 g (3.43 ± 0.51 mg) dry weight resin. Long-term kinetic adsorption of resin-saponin method (>24 hours) should be conducted to obtain optimum freed saponin extract. Besides that, sample treated with 0.1 g dry weight resin had high free radical scavenging value of 50.33 ± 2.74% compared to sample treated with 0.5 g dry weight resin that had low free radical scavenging value of 24.54 ± 1.66% dry weights. Total saponin content (mg), total phenolic content (mg GAE) and free radical scavenging activity (%) was investigated to determine the interaction of those compounds with Amberlite® IRA-67. The RP-HPLC analysis using ursolic acid as standard at 203 nm showed no peak even though ursolic acid was one of the saponin components that was ubiquitous in plant kingdom. The absence of peak was due to weak solubility of ursolic acid in water and since it was only soluble in solvent with moderate polarity. The Pearson's correlation coefficient for total saponin content (mg) versus total phenolic content (mg GAE) and radical scavenging activity (%) were +0.959 and +0.807. Positive values showed that whenever there was an increase in saponin content (mg), the phenolic content (mg GAE) and radical scavenging activity (%) would also increase. However, as the resin-saponin adsorption was carried out, there was a significant decrease of radical scavenging activity

  17. Novel silica-based ion exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-11-01

    Eichrom`s highly successful Diphonixo resin resembles a conventional ion exchange resin in its use of sulfonic acid ligands on a styrene- divinylbenzene matrix. Diphonix resin exhibits rapid exchange kinetics that allow economical operation of ion exchange systems. Unlike conventional resins, Diphonix resin contains chelating ligands that are diphosphonic acid groups that recognize and remove the targeted metals and reject the more common elements such as sodium, calcium and magnesium. This latter property makes Diphonix ideal for many industrial scale applications, including those involving waste treatment. For treatment of low-level, transuranic (TRU) and high- level radioactive wastes, Diphonix`s polystyrene backbone hinders its application due to radiolytic stability of the carbon-hydrogen bonds and lack of compatibility with expected vitrification schemes. Polystyrene-based Diphonix is approximately 60% carbon- hydrogen. In response to an identified need within the Department of Energy for a resin with the positive attributes of Diphonix that also exhibits greater radiolytic stability and final waste form compatibility, Eichrom has successfully developed a new, silica-based resin version of Diphonix. Target application for this new resin is for use in environmental restoration and waste management situations involving the processing of low-level, transuranic and high-level radioactive wastes. The resin can also be used for processing liquid mixed waste (waste that contains low level radioactivity and hazardous constituents) including mixed wastes contaminated with organic compounds. Silica-based Diphonix is only 10% carbon-hydrogen, with the bulk of the matrix silica.

  18. Microbiological study of water-softener resins.

    Science.gov (United States)

    Stamm, J M; Engelhard, W E; Parsons, J E

    1969-09-01

    Microbial identification using effluents backflushed from exhausted urban and rural tank resins and cleaned resins containing the sulfonated copolymer of styrene and divinylbenzene (SDB) were completed, along with microbial assessment of the concentrated stock salt brine. Forty-four different bacterial and fungal genera were identified. Extensive biochemical and animal virulence tests completed on one of the six bacterial salt brine isolates indicated a pathogenic staphylococcal strain. The retention of Staphylococcus aureus, a Flavobacterium sp, and Escherichia coli B bacteriophage was demonstrated both by using the nonexhausted sodium-regenerated resin and by using the same resin exchanged with different mono-, di-, and trivalent cations. Effluent counts completed after bacterial seepage through the resins indicated the Pb(++) exchanged resin removed 55% of the bacteria; Na(+), Fe(++), and Al(+++) removed 31 to 36% and Ca(++) and Cu(++) removed about 10 to 15%. Seventy per cent or more of the bacteriophage was removed by Fe(++), Cu(++), and Al(+++), whereas the Ca(++) and Na(++) cations removed 25 to 31%. Over a 77-day period, nonsterile tap water was passed through bacterial seeded and uninoculated SDB (Na) resin columns. Effluent and resin elution counts demonstrated the growth and survival of 2 different bacteria per column. Increased bacterial retention, survival, and multiplication occurred concomitantly with accumulation of organic and inorganic materials and the Ca(++) and Mg(++) cations from the tap water. Furthermore, microbial elution from resin particles taken from column depths of 1, 8, and 16 cm indicated a bacterial diminution with increasing depths.

  19. Heat-cured Acrylic Resin versus Light-activated Resin: A Patient ...

    African Journals Online (AJOL)

    Context: Although light-activated resins (Eclipse) have been reported to possess superior physical and mechanical properties compared with the heat-cured acrylic resins (Lucitone-199), a few studies have compared overdentures with a locator attachment constructed from heat-cured acrylic resins with those constructed ...

  20. Influence of hydrophilic pre-treatment on resin bonding to zirconia ceramics.

    Science.gov (United States)

    Noro, Akio; Kameyama, Atsushi; Haruyama, Akiko; Takahashi, Toshiyuki

    2015-01-01

    Atmospheric plasma or ultraviolet (UV) treatment alters the surface characteristics of tetragonal zirconia polycrystal (TZP), increasing its hydrophilicity by reducing the contact angle against water to zero. This suggests that such treatment would increase the wettability of bonding resin. The purpose of this study was to determine how increasing the hydrophilicity of TZP through plasma irradiation, UV treatment, or application of ceramic primer affected initial bonding with resin composites. Here, the effect of each pre-treatment on the hydrophilicity of TZP surfaces was determined by evaluating change in shear bond strength. Plasma irradiation, UV, or ceramic primer pre-treatment showed no significant effect on bonding strength between TZP surfaces and resin composites. In addition, alumina blasting yielded no significant increase in bond strength. Plasma irradiation, UV treatment, or ceramic primer pre-treatment did not lead to significant increase in bond strength between TZP and resin composites.

  1. Effects of trimethylsilane plasma coating on the hydrophobicity of denture base resin and adhesion of Candida albicans on resin surfaces.

    Science.gov (United States)

    Liu, Tianshuang; Xu, Changqi; Hong, Liang; Garcia-Godoy, Franklin; Hottel, Timothy; Babu, Jegdish; Yu, Qingsong

    2017-12-01

    Candida-associated denture stomatitis is the most common oral mucosal lesion among denture wearers. Trimethylsilane (TMS) plasma coating may inhibit the growth of Candida albicans on denture surfaces. The purpose of this in vitro study was to investigate whether TMS plasma coatings can effectively reduce C albicans adhesion on denture base acrylic resin surfaces. Sixty denture base acrylic resin disks with smooth and rough surfaces were prepared and were either left untreated (control group) or coated with TMS monomer (experimental group) by using plasma. Contact angles were measured immediately after TMS plasma coating. The morphology of C albicans adhesion was observed with scanning electron microscopy (SEM). Energy-dispersive spectroscopy (EDS) was used to characterize the elemental composition of the specimen surface. An adhesion test was performed by incubating the resin disk specimens in C albicans suspensions (1×10 7 cells/mL) at 37°C for 24 hours and further measuring the optical density of the C albicans by using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay test. One-way ANOVA and 2-way ANOVA were followed by a post hoc test analysis (α=.05). The group with TMS coating exhibited a more hydrophobic surface than the control group. EDS analysis revealed successful TMS plasma coating. The difference in the mean contact angles between the uncoated group and the TMS-coated group was statistically significant (Pcoating than on the surfaces of the experimental group. In the adhesion test, the amount of C albicans adhering to the surface of denture base resin with the TMS coating was significantly less than that on the surfaces without TMS coating (Pcoating significantly reduced the adhesion of C albicans to the denture base resin and may reduce denture stomatitis. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  2. Nylon biodegradation by lignin-degrading fungi.

    Science.gov (United States)

    Deguchi, T; Kakezawa, M; Nishida, T

    1997-01-01

    The biodegradation of nylon by lignin-degrading fungi was investigated. The fungus IZU-154 significantly degraded nylon-66 membrane under ligninolytic conditions. Nuclear magnetic resonance analysis showed that four end groups, CHO, NHCHO, CH3, and CONH2, were formed in the biodegraded nylon-66 membranes, suggesting that nylon-66 was degraded oxidatively. PMID:8979361

  3. Nylon biodegradation by lignin-degrading fungi.

    OpenAIRE

    Deguchi, T; Kakezawa, M; Nishida, T

    1997-01-01

    The biodegradation of nylon by lignin-degrading fungi was investigated. The fungus IZU-154 significantly degraded nylon-66 membrane under ligninolytic conditions. Nuclear magnetic resonance analysis showed that four end groups, CHO, NHCHO, CH3, and CONH2, were formed in the biodegraded nylon-66 membranes, suggesting that nylon-66 was degraded oxidatively.

  4. Raman spectroscopic study of the aging and nitration of actinide processing anion-exchange resins in concentrated nitric acid

    International Nuclear Information System (INIS)

    Buscher, C. T.; Donohoe, R. J.; Mecklenburg, S. L.; Berg, J. M.; Tait, C. D.; Huchton, K. M.; Morris, D. E.

    1999-01-01

    Degradation of two types of anion exchange resins, Dowex 11 and Reillex HPQ, from the action of concentrated nitric acid (4 to 12 M) and radiolysis [from depleted uranium as UO 2 2+ nitrate species and 239 Pu as Pu(IV) nitrate species] was followed as a function of time with Raman vibrational spectroscopy. Elevated temperatures (∼50 degree sign C) were used in the absence of actinide metal loading to simulate longer exposures of the resin to a HNO 3 process stream and waste storage conditions. In the absence of actinide loading, only minor changes in the Dowex resin at acid concentrations ≤10 M were observed, while at 12 M acid concentration, the emergence of a Raman peak at 1345 cm-1 indicates the addition of nitro functional groups to the resin. Similar studies with the Reillex resin show it to be more resistant to nitric acid attack at all acid concentrations. Incorporation of weakly radioactive depleted uranium as the UO 2 2+ nitrate species to the ion-exchange sites of Dowex 11 under differing nitric acid concentrations (6 to 12 M) at room temperature showed no Raman evidence of resin degradation or nitration, even after several hundred days of contact. In contrast, Raman spectra for Dowex 11 in the presence of 239 Pu as Pu(IV) nitrate species reveal numerous changes indicating resin alterations, including a new mode at 1345 cm-1 consistent with a Pu(IV)-nitrate catalyzed addition of nitro groups to the resin backbone. (c) 2000 Society for Applied Spectroscopy

  5. Study on Concrete Containing Recycled Aggregates Immersed in Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Adnan Suraya Hani

    2017-01-01

    Full Text Available In recent decades, engineers have sought a more sustainable method to dispose of concrete construction and demolition waste. One solution is to crush this waste concrete into a usable gradation for new concrete mixes. This not only reduces the amount of waste entering landfills but also alleviates the burden on existing sources of quality natural concrete aggregates. There are too many kinds of waste but here constructions waste will be the priority target that should be solved. It could be managed by several ways such as recycling and reusing the concrete components, and the best choice of these components is the aggregate, because of the ease process of recycle it. In addition, recycled aggregates and normal aggregates were immersed in epoxy resin and put in concrete mixtures with 0%, 5%, 10% and 20% which affected the concrete mixtures properties. The strength of the concrete for both normal and recycled aggregates has increased after immersed the aggregates in epoxy resin. The percentage of water absorption and the coefficient of water permeability decreased with the increasing of the normal and the recycled aggregates immersed in epoxy resin. Generally the tests which have been conducted to the concrete mixtures have a significant results after using the epoxy resin with both normal and recycled aggregates.

  6. Effect of Ingested Liquids on Color Change of Composite Resins.

    Science.gov (United States)

    Malek Afzali, Beheshteh; Ghasemi, Amir; Mirani, Asrin; Abdolazimi, Zahra; Akbarzade Baghban, Alireza; Kharazifard, Mohammad Javad

    2015-08-01

    Color change of composite restorations is well known to dentists. However, the effect of commonly consumed drinks on discoloration of composite resins has yet to be determined. This study sought to assess the color change of a nanofilled (Premise) and a flowable composite resin (Premise flowable) following simulated consumption of tea, cola, iron drops and multivitamin syrup. Forty disk-shaped specimens (7 mm in diameter and 2 mm thick) were fabricated from each composite resin. The baseline color values were measured according to the CIE L*a*b* system using digital imaging. The specimens of each restorative material were randomly divided into five groups (eight each) according to the storage media namely tea, cola, iron drops, multivitamin syrup or distilled water (control). The specimens were immersed in staining solutions for three hours daily over a 40-day test period. Following this, the color change values (ΔE*) were calculated. For statistical analyses, the color differences were analyzed using two-way ANOVA and Tukey's test (Pcomposite resins (P>0.05). In both composite materials, the difference among the solutions was not significant (P>0.05). Under the tested experimental conditions, both restorative materials were susceptible to discoloration by all four staining solutions. The color change values were not related to the solution or the type of material used.

  7. Resin infiltration of proximal caries lesions differing in ICDAS codes.

    Science.gov (United States)

    Paris, Sebastian; Bitter, Kerstin; Naumann, Michael; Dörfer, Christof E; Meyer-Lueckel, Hendrik

    2011-04-01

    Resin infiltration of non-cavitated proximal caries lesions has been shown to inhibit further demineralization. However, the effect of resin infiltration in cavitated lesions is unknown. Therefore, the aim of this in vitro study was to evaluate infiltration patterns of proximal caries lesions differing in International Caries Detection and Assessment System (ICDAS) codes. Extracted human molars and premolars showing proximal caries lesions with and without cavitations (ICDAS codes 2-5) were etched with 15% hydrochloric acid gel and resin infiltrated according to the manufacturer's instructions. Three sections from each lesion were prepared and analyzed using a dual-fluorescence staining technique and confocal microscopy. The dimensions of the demineralized and cavitated lesions areas, as well as the resin-infiltrated parts within these lesions, were measured. The demineralized parts were infiltrated from 73% to 100% (median values) but the cavities were filled only negligibly (0-5%). Teeth that had an ICDAS code of 5 showed a significantly lower percentage infiltration/filling of lesions compared to teeth with ICDAS codes of 2 and 3. It was concluded that under in vitro conditions the tested infiltrant penetrates most parts of the demineralized enamel but is not capable of filling up cavities and therefore the efficacy of caries infiltration, particularly in lesions with larger cavitations, might be impaired. © 2011 Eur J Oral Sci.

  8. Bond strength between acrylic resin and maxillofacial silicone

    Directory of Open Access Journals (Sweden)

    Marcela Filié Haddad

    2012-12-01

    Full Text Available The development of implant dentistry improved the possibilities of rehabilitation with maxillofacial prosthesis. However, clinically it is difficult to bond the silicone to the attachment system. OBJECTIVES: This study aimed to evaluate the effect of an adhesive system on the bond strength between acrylic resin and facial silicone. MATERIAL AND METHODS: A total of 120 samples were fabricated with auto-polymerized acrylic resin and MDX 4-4210 facial silicone. Both materials were bonded through mechanical retentions and/or application of primers (DC 1205 primer and Sofreliner primer S and adhesive (Silastic Medical Adhesive Type A or not (control group. Samples were divided into 12 groups according to the method used to attach the silicone to the acrylic resin. All samples were subjected to a T-peel test in a universal testing machine. Failures were classified as adhesive, cohesive or mixed. The data were evaluated by the analysis of variance (ANOVA and the Tukey's HSD test (α=.05. RESULTS: The highest bond strength values (5.95 N/mm; 3.07 N/mm; 4.75 N/mm were recorded for the samples that received a Sofreliner primer application. These values were significantly higher when the samples had no scratches and did not receive the application of Silastic Medical Adhesive Type A. CONCLUSIONS: The most common type of failure was adhesive. The use of Sofreliner primer increased the bond strength between the auto-polymerized acrylic resin and the Silastic MDX 4-4210 facial silicone.

  9. Microhardness of heat cure acrylic resin after treatment with disinfectants.

    Science.gov (United States)

    Amin, Faiza; Rehman, Abdur; Abbas, Muhammad

    2015-08-01

    To evaluate the effect of disinfectants and distilled water on the micro-hardness of heat cure acrylic resins. The case-control study was conducted at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, and Nadirshaw Edulji Dinshaw University of Engineering and Technology, Karachi, from April to October 2011. Specimens were fabricated from heat cure acrylic resin material and they were divided into four equal groups. Group 1 was evaluated at baseline and was taken as the control group. Group 2 was immersed in distilled water for 20 minutes, Group 3 in1% sodium hypochlorite for 20 minutes, and Group 4 in 2% alkaline gluteraldehyde for 10 minutes. All specimens were polished, stored in distilled water for 24 hours prior to experiment. All the specimens were immersed twice daily for a total of 60 days after which they were tested for Vickers micro-hardness test. Statistical analysis was conducted with one-way analysis of variance and Tukey post hoc test (a=0.05). There were 72 specimens divided into four groups of 18(25%) each. Statistically significant differences were found among all groups (pacrylic resins. Group 4 showed the most reduction in the hardness value which was followed by Group 3. The hardness of heat cure acrylic resin was affected by disinfectants.

  10. Special Resins for Stereolithography: In Situ Generation of Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Gabriele Taormina

    2018-02-01

    Full Text Available The limited availability of materials with special properties represents one of the main limitations to a wider application of polymer-based additive manufacturing technologies. Filled resins are usually not suitable for vat photo-polymerization techniques such as stereolithography (SLA or digital light processing (DLP due to a strong increment of viscosity derived from the presence of rigid particles within the reactive suspension. In the present paper, the possibility to in situ generate silver nanoparticles (AgNPs starting from a homogeneous liquid system containing a well dispersed silver salt, which is subsequently reduced to metallic silver during stereolithographic process, is reported. The simultaneous photo-induced cross-linking of the acrylic resin produces a filled thermoset resin with thermal-mechanical properties significantly enhanced with respect to the unfilled resin, even at very low AgNPs concentrations. With this approach, the use of silver salts having carbon-carbon double bonds, such as silver acrylate and silver methacrylate, allows the formation of a nanocomposite structure in which the release of by-products is minimized due to the active role of all the reactive components in the three dimensional (3D-printing processes. The synergy, between this nano-technology and the geometrical freedom offered by SLA, could open up a wide spectrum of potential applications for such a material, for example in the field of food packaging and medical and healthcare sectors, considering the well-known antimicrobial effects of silver nanoparticles.

  11. Enhanced thermal conductivity of carbon fiber/phenolic resin composites by the introduction of carbon nanotubes

    Science.gov (United States)

    Kim, Y. A.; Kamio, S.; Tajiri, T.; Hayashi, T.; Song, S. M.; Endo, M.; Terrones, M.; Dresselhaus, M. S.

    2007-02-01

    The authors report a significant enhancement in the thermal conductivity of a conventional carbon fiber/phenolic resin composite system when adding highly crystalline multiwalled carbon nanotubes. They demonstrate that 7wt% of carbon nanotubes dispersed homogeneously in a phenolic resin acted as an effective thermal bridge between adjacent carbon fibers and resulted in an enhancement of the thermal conductivity (e.g., from 250to393W/mK). These results indicate that highly crystalline carbon nanotubes can be used as a multifunctional filler to enhance simultaneously the mechanical and thermal properties of the carbon fiber/phenolic resin composites.

  12. Gastroprotective effect of the Mapuche crude drug Araucaria araucana resin and its main constituents.

    Science.gov (United States)

    Schmeda-Hirschmann, Guillermo; Astudillo, Luis; Rodríguez, Jaime; Theoduloz, Cristina; Yáñez, Tania

    2005-10-03

    The resin from the tree Araucaria araucana (Araucariaceae) has been used since pre-columbian times by the Mapuche amerindians to treat ulcers. The gastroprotective effect of the resin was assessed in the ethanol-HCl-induced gastric ulcer in mice showing a dose-dependent gastroprotective activity at 100, 200 and 300 mg/kg per os. The main three diterpene constituents of the resin, namely imbricatolic acid, 15-hydroxyimbricatolal and 15-acetoxyimbricatolic acid were isolated and evaluated for gastroprotective effect at doses of 50, 100 and 200 mg/kg. A dose-related gastroprotective effect with highly significant activity (PMapuche culture.

  13. Cation immobilization in pyrolyzed simulated spent ion exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Luca, Vittorio, E-mail: vluca@cnea.gov.ar [Programa Nacional de Gestion de Residuos Radiactivos, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Av. General, Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); Bianchi, Hugo L. [Gerencia de Quimica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Av. General, Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); ECyT, Universidad Nacional de General San Martin, Campus Miguelete, Ed. Tornavias, Martin de Irigoyen 3100, 1650 San Martin (Argentina); Conicet, Av. Rivadavia 1917, 1033 Buenos Aires (Argentina); Manzini, Alberto C. [Programa Nacional de Gestion de Residuos Radiactivos, Comision Nacional de Energia Atomica, Av. Del Libertador 8250, CP 1429, Ciudad Autonoma de Buenos Aires (Argentina)

    2012-05-15

    Significant quantities of spent ion exchange resins that are contaminated by an assortment of radioactive elements are produced by the nuclear industry each year. The baseline technology for the conditioning of these spent resins is encapsulation in ordinary Portland cement which has various shortcomings none the least of which is the relatively low loading of resin in the cement and the poor immobilization of highly mobile elements such as cesium. The present study was conducted with cationic resin samples (Lewatit S100) loaded with Cs{sup +}, Sr{sup 2+}, Co{sup 2+}, Ni{sup 2+} in roughly equimolar proportions at levels at or below 30% of the total cation exchange capacity. Low temperature thermal treatment of the resins was conducted in inert (Ar), or reducing (CH{sub 4}) gas atmospheres, or supercritical ethanol to convert the hydrated polymeric resin beads into carbonaceous materials that contained no water. This pyrolytic treatment resulted in at least a 50% volume reduction to give mechanically robust spherical materials. Scanning electron microscope investigations of cross-sections of the beads combined with energy dispersive analysis showed that initially all elements were uniformly distributed through the resin matrix but that at higher temperatures the distribution of Cs became inhomogeneous. Although Cs was found in the entire cross-section, a significant proportion of the Cs occurred within internal rings while a proportion migrated toward the outer surfaces to form a crustal deposit. Leaching experiments conducted in water at 25 Degree-Sign C showed that the divalent contaminant elements were very difficult to leach from the beads heated in inert atmospheres in the range 200-600 Degree-Sign C. Cumulative fractional loses of the order of 0.001 were observed for these divalent elements for temperatures below 500 Degree-Sign C. Regardless of the processing temperature, the cumulative fractional loss of Cs in water at 25 Degree-Sign C reached a plateau or

  14. Cation immobilization in pyrolyzed simulated spent ion exchange resins

    International Nuclear Information System (INIS)

    Luca, Vittorio; Bianchi, Hugo L.; Manzini, Alberto C.

    2012-01-01

    Significant quantities of spent ion exchange resins that are contaminated by an assortment of radioactive elements are produced by the nuclear industry each year. The baseline technology for the conditioning of these spent resins is encapsulation in ordinary Portland cement which has various shortcomings none the least of which is the relatively low loading of resin in the cement and the poor immobilization of highly mobile elements such as cesium. The present study was conducted with cationic resin samples (Lewatit S100) loaded with Cs + , Sr 2+ , Co 2+ , Ni 2+ in roughly equimolar proportions at levels at or below 30% of the total cation exchange capacity. Low temperature thermal treatment of the resins was conducted in inert (Ar), or reducing (CH 4 ) gas atmospheres, or supercritical ethanol to convert the hydrated polymeric resin beads into carbonaceous materials that contained no water. This pyrolytic treatment resulted in at least a 50% volume reduction to give mechanically robust spherical materials. Scanning electron microscope investigations of cross-sections of the beads combined with energy dispersive analysis showed that initially all elements were uniformly distributed through the resin matrix but that at higher temperatures the distribution of Cs became inhomogeneous. Although Cs was found in the entire cross-section, a significant proportion of the Cs occurred within internal rings while a proportion migrated toward the outer surfaces to form a crustal deposit. Leaching experiments conducted in water at 25 °C showed that the divalent contaminant elements were very difficult to leach from the beads heated in inert atmospheres in the range 200–600 °C. Cumulative fractional loses of the order of 0.001 were observed for these divalent elements for temperatures below 500 °C. Regardless of the processing temperature, the cumulative fractional loss of Cs in water at 25 °C reached a plateau or steady-state within the first 24 h increasing only

  15. Comparison of Cashew Nut Shell Liquid (CNS ) Resin with ...

    African Journals Online (AJOL)

    synthetic) resin. Compressive and tensile strength tests conducted proved that composites developed with cashew nut shell liquid (CNSL) resin were comparable to those developed with polyester resin. In the results, CNSL has an ultimate ...

  16. The combined effect of food-simulating solutions, brushing and staining on color stability of composite resins

    Science.gov (United States)

    Silva, Tânia Mara Da; Sales, Ana Luísa Leme Simões; Pucci, Cesar Rogerio; Borges, Alessandra Bühler; Torres, Carlos Rocha Gomes

    2017-01-01

    Abstract Objective: This study evaluated the effect of food-simulating media associated with brushing and coffee staining on color stability of different composite resins. Materials and methods: Eighty specimens were prepared for each composite: Grandio SO (Voco), Amaris (Voco), Filtek Z350XT (3M/ESPE), Filtek P90 (3M/ESPE). They were divided into four groups according to food-simulating media for 7 days: artificial saliva (control), heptane, citric acid and ethanol. The composite surface was submitted to 10,950 brushing cycles (200 g load) in an automatic toothbrushing machine. The specimens were darkened with coffee solution at 37 °C for 24 h. After each treatment, color measurements were assessed by spectrophotometry, using CIE L*a*b* system. The overall color change (ΔE) was determined for each specimen at baseline (C1) and after the treatments (food-simulating media immersion/C2, brushing/C3 and dye solution/C4). Data were analyzed by two-way repeated measures ANOVA and Tukey’s tests (p composites (p = .001), time (p = .001) and chemical degradation (p = .002). The mean of ΔE for composites were: Z350XT (5.39)a, Amaris (3.89)b, Grandio (3.75)bc, P90 (3.36)c. According to food-simulating media: heptane (4.41)a, citric acid (4.24)a, ethanol (4.02)ab, artificial saliva (3.76)b. For the treatments: dye solution (4.53)a, brushing (4.26)a, after food-simulating media (3.52)b. Conclusions: The composite resin Filtek Z350XT showed significantly higher staining than all other composite resin tested. The immersion in heptane and citric acid produced the highest color alteration than other food-simulating media. The exposure of samples to brushing protocols and darkening in coffee solution resulted in significant color alteration of the composite resins. PMID:28642926

  17. Resin composite for sealing and its use in a solar cell. Fushiyo jushi soseibutsu oyobi sore wo mochiita taiyo denchi

    Energy Technology Data Exchange (ETDEWEB)

    Toma, H.; Mimura, T.; Takehara, N.

    1994-01-28

    This invention presents resin composites for sealing of a solar cell composed of a hardening resin and a thermoplastic resin which has a number average molecular weight larger than that of the hardening resin and is soluble in the hardening resin, and the invention affords a solar cell to endure a long-term stable operation and to give a good performance. The hardening resin includes unsaturated polyester resin, phenolic resin, alkyd resin, unsaturated acrylic resin, epoxy resin, polyurethane resin, melamine resin, diallyl phthalate resin, their oligomers and their modifications. The thermoplastic resin includes saturated polyester resin, phenolic resin, acrylic resin, styrene resin, epoxy resin, polyurethane resin, polyvinyl acetate resin, polyvinyl chloride resin, polyvinyl alcohol resin, polyacetal resin, their modifications and their copolymer resin. 2 figs., 3 tabs.

  18. Mechanical Properties and Sliding-impact Wear Resistance of Self-adhesive Resin Cements.

    Science.gov (United States)

    Furuichi, T; Takamizawa, T; Tsujimoto, A; Miyazaki, M; Barkmeier, W W; Latta, M A

    2016-01-01

    The present study determined the mechanical properties and impact-sliding wear characteristics of self-adhesive resin cements. Five self-adhesive resin cements were used: G-CEM LinkAce, BeautiCem SA, Maxcem Elite, Clearfil SA Automix, and RelyX Unicem 2. Clearfil Esthetic Cement was employed as a control material. Six specimens for each resin cement were used to determine flexural strength, elastic modulus, and resilience according to ISO specification #4049. Ten specimens for each resin cement were used to determine the wear characteristics using an impact-sliding wear testing apparatus. Wear was generated using a stainless-steel ball bearing mounted inside a collet assembly. The maximum facet depth and volume loss were determined using a noncontact profilometer in combination with confocal laser scanning microscopy. Data were evaluated using analysis of variance followed by the Tukey honestly significantly different test (α=0.05). The flexural strength of the resin cements ranged from 68.4 to 144.2 MPa; the elastic modulus ranged from 4.4 to 10.6 GPa; and the resilience ranged from 4.5 to 12.0 MJ/m(3). The results for the maximum facet depth ranged from 25.2 to 235.9 μm, and volume loss ranged from 0.0107 to 0.5258 mm(3). The flexural properties and wear resistance were found to vary depending upon the self-adhesive resin cement tested. The self-adhesive cements tended to have lower mechanical properties than the conventional resin cement. All self-adhesive resin cements, apart from G-CEM LinkAce, demonstrated significantly poorer wear resistance than did the conventional resin cement.

  19. Inhibitory effect on Streptococcus mutans and mechanical properties of the chitosan containing composite resin

    Directory of Open Access Journals (Sweden)

    Ji-Sun Kim

    2013-02-01

    Full Text Available Objectives This study evaluated the antibacterial effect and mechanical properties of composite resins (LCR, MCR, HCR incorporating chitosan with three different molecular weights (L, Low; M, Medium; H, High. Materials and Methods Streptococcus (S. mutans 100 mL and each chitosan powder were inoculated in sterilized 10 mL Brain-Heart Infusion (BHI solution, and was centrifuged for 12 hr. Absorbance of the supernatent was measured at OD660 to estimate the antibacterial activities of chitosan. After S. mutans was inoculated in the disc shaped chitosan-containing composite resins, the disc was cleansed with BHI and diluted with serial dilution method. S. mutans was spread on Mitis-salivarius bacitracin agar. After then, colony forming unit (CFU was measured to verify the inhibitory effect on S. mutans biofilm. To ascertain the effect on the mechanical properties of composite resin, 3-point bending and Vickers hardness tests were done after 1 and 3 wk water storage, respectively. Using 2-way analysis of variance (ANOVA and Scheffe test, statistical analysis was done with 95% significance level. Results All chitosan powder showed inhibition effect against S. mutans. CFU number in chitosan-containing composite resins was smaller than that of control resin without chitosan. The chitosan containing composite resins did not show any significant difference in flexural strength and Vickers hardness in comparison with the control resin. However, the composite resin, MCR showed a slightly decreased flexural strength and the maximum load than those of control and the other composite resins HCR and LCR. Conclusions LCR and HCR would be recommended as a feasible antibacterial restorative due to its antibacterial nature and mechanical properties.

  20. Diclofenac removal in urine using strong-base anion exchange polymer resins.

    Science.gov (United States)

    Landry, Kelly A; Boyer, Treavor H

    2013-11-01

    One of the major sources of pharmaceuticals in the environment is wastewater effluent of which human urine contributes the majority of pharmaceuticals. Urine source separation has the potential to isolate pharmaceuticals at a higher concentration for efficient removal as well as produce a nutrient byproduct. This research investigated the efficacy of using strong-base anion exchange polymer resins to remove the widely detected and abundant pharmaceutical, diclofenac, from synthetic human urine under fresh and ureolyzed conditions. The majority of experiments were conducted using a strong-base, macroporous, polystyrene resin (Purolite A520E). Ion-exchange followed a two-step removal rate with rapid removal in 1 h and equilibrium removal in 24 h. Diclofenac removal was >90% at a resin dose of 8 mL/L in both fresh and ureolyzed urine. Sorption of diclofenac onto A520E resin was concurrent with desorption of an equivalent amount of chloride, which indicates the ion-exchange mechanism is occurring. The presence of competing ions such as phosphate and citrate did not significantly impact diclofenac removal. Comparisons of three polystyrene resins (A520E, Dowex 22, Dowex Marathon 11) as well as one polyacrylic resin (IRA958) were conducted to determine the major interactions between anion exchange resin and diclofenac. The results showed that polystyrene resins provide the highest level of diclofenac removal due to electrostatic interactions between quaternary ammonium functional groups of resin and carboxylic acid of diclofenac and non-electrostatic interactions between resin matrix and benzene rings of diclofenac. Diclofenac was effectively desorbed from A520E resin using a regeneration solution that contained 4.5% (m/m) NaCl in an equal-volume mixture of methanol and water. The greater regeneration efficiency of the NaCl/methanol-water mixture over the aqueous NaCl solution supports the importance of non-electrostatic interactions between resin matrix and benzene rings

  1. Curing kinetics of alkyd/melamine resin mixtures

    OpenAIRE

    Jovičić Mirjana C.; Radičević Radmila Ž.

    2009-01-01

    Alkyd resins are the most popular and useful synthetic resins applied as the binder in protective coatings. Frequently they are not used alone but are modified with other synthetic resins in the manufacture of the coatings. An alkyd/melamine resin mixture is the usual composition for the preparation of coating called 'baking enamel' and it is cured through functional groups of resins at high temperatures. In this paper, curing kinetics of alkyd resins based on castor oil and dehydrated castor...

  2. Preparation and properties studies of UV-curable silicone modified epoxy resin composite system.

    Science.gov (United States)

    Yu, Zhouhui; Cui, Aiyong; Zhao, Peizhong; Wei, Huakai; Hu, Fangyou

    2018-01-01

    Modified epoxy suitable for ultraviolet (UV) curing is prepared by using organic silicon toughening. The curing kinetics of the composite are studied by dielectric analysis (DEA), and the two-phase compatibility of the composite is studied by scanning electron microscopy (SEM). The tensile properties, heat resistance, and humidity resistance of the cured product are explored by changing the composition ratio of the silicone and the epoxy resin. SEM of silicone/epoxy resin shows that the degree of cross-linking of the composites decreases with an increase of silicone resin content. Differential thermal analysis indicates that the glass transition temperature and the thermal stability of the composites decrease gradually with an increase of silicone resin content. The thermal degradation rate in the high temperature region, however, first decreases and then increases. In general, after adding just 10%-15% of the silicone resin and exposing to light for 15 min, the composite can still achieve a better curing effect. Under such conditions, the heat resistance of the cured product decreases a little. The tensile strength is kept constant so that elongation at breakage is apparently improved. The change rate after immersion in distilled water at 60°C for seven days is small, which shows excellent humidity resistance.

  3. Concentrating cesium-137 from seawater using resorcinol-formaldehyde resin for radioecological monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Egorin, Andrei; Tokar, Eduard; Tutov, Mikhail; Avramenko, Valentin [Institute of Chemistry FEBRAS, Vladivostok (Russian Federation); Far Eastern Federal Univ., Vladivostok (Russian Federation); Palamarchuk, Marina; Marinin, Dmitry [Institute of Chemistry FEBRAS, Vladivostok (Russian Federation)

    2017-04-01

    A method of preconcentrating cesium-137 from seawater using a resorcinol-formaldehyde resin, which enables one to optimize the ecological monitoring procedure, has been suggested. Studies of sorption of cesium-137 from seawater by resorcinol-formaldehyde resin have been performed, and it has been demonstrated that the cation exchanger is characterized by high selectivity with respect to cesium-137. It was found that the selectivity depended on the temperature of resin solidification and the seawater pH value. The maximal value of the cesium-137 distribution coefficient is equal to 4.1-4.5 x 10{sup 3} cm{sup 3} g{sup -1}. Under dynamic conditions, the ion-exchange resin capacity is 310-910 bed volumes depending on the seawater pH, whereas the efficiency of cesium removal exceeds 95%. The removal of more than 95% of cesium-137 has been attained using 1-3 M solutions of nitric acid: here, the eluate volume was 8-8.4 bed volumes. Application of 3 M solution of nitric acid results in resin degradation with the release of gaseous products.

  4. The influence of plutonium concentration and solution flow rate on the effective capacity of macroporous anion exchange resin

    International Nuclear Information System (INIS)

    Marsh, S.F.; Gallegos, T.D.

    1987-07-01

    The principal aqueous process used to recover and purify plutonium at the Los Alamos Plutonium Facility is anion exchange in nitric acid. Previous studies with gel-type anion exchange resin have shown an inverse relationship between plutonium concentration in the feed solution and the optimum flow rate for this process. Because gel-type resin has been replaced with macroporous resin at Los Alamos, the relationship between plutonium concentration and solution flow rate was reexamined with the selected Lewatit MP-500-FK resin using solutions of plutonium in nitric acid and in nitric acid with high levels of added nitrate salts. Our results with this resin differ significantly from previous data obtained with gel-type resin. Flow-rate variation from 10 to 80 liters per hour had essentially no effect on the measured quantities of plutonium sorbed by the macroporous resin. However, the effect of plutonium concentration in the feed solutions was pronounced, as feed solutions that contained the highest concentrations of plutonium also produced the highest resin loadings. The most notable effect of high concentrations of dissolved nitrate salts in these solutions was an increased resin capacity for plutonium at low flow rates. 16 refs., 7 figs., 2 tabs

  5. Dryland resources, livelihoods and institutions : diversity and dynamics in use and management of gum and resin trees in Ethiopia

    NARCIS (Netherlands)

    Teshale Woldeamanuel Habebo, Teshale

    2011-01-01

    Dry woodlands comprise the largest forest resources in Ethiopia. An important feature of these forests is their richness in Acacia, Boswellia and Commiphora (ABC) species that produce gum and resin. Gums/resins significantly contribute to rural livelihoods, the national economy, and ecosystem

  6. Input to Resin Column Structural Analysis if Autocatalytic Resin Reaction Occurs in HB-Line Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Hallman, D.F.

    2001-07-10

    Solutions of plutonium in nitric acid are purified and concentrated using anion resin prior to precipitation. There have been instances of resin column explosions caused by autocatalytic reactions of anion resins in nitric acid within the DOE complex

  7. Cure reaction of epoxy resins catalyzed by graphite-based nanofiller

    Science.gov (United States)

    Corcione, C. Esposito; Acocella, Maria Rosaria; Giuri, Antonella; Maffezzoli, Alfonso; Guerra, Gaetano

    2015-12-01

    A significant effort was directed to the synthesis of graphene stacks/epoxy nanocomposites and to the analysis of the effect of a graphene precursor on cure reaction of a model epoxy matrix. A comparative thermal analysis of epoxy resins filled with an exfoliated graphite oxide eGO were conducted. The main aim was to understand the molecular origin of the influence of eGO on the Tg of epoxy resins. The higher Tg values previously observed for low curing temperatures, for epoxy resins with graphite-based nanofillers, were easily rationalized by a catalytic activity of graphitic layers on the reaction between the epoxy and amine groups of the resin, which leads to higher crosslinking density in milder conditions. A kinetic analysis of the cure mechanism of the epoxy resin associated to the catalytical activity of the graphite based filler was performed by isothermal DSC measurements. The DSC results showed that the addition of graphite based filler greatly increased the enthalpy of epoxy reaction and the reaction rate, confirming the presence of a catalytic activity of graphitic layers on the crosslinking reaction between the epoxy resin components (epoxide oligomer and di-amine). A kinetic modelling analysis, arising from an auto-catalyzed reaction mechanism, was finally applied to isothermal DSC data, in order to predict the cure mechanism of the epoxy resin in presence of the graphite based nanofiller.

  8. Perchlorate adsorption and desorption on activated carbon and anion exchange resin.

    Science.gov (United States)

    Yoon, In-Ho; Meng, Xiaoguang; Wang, Chao; Kim, Kyoung-Woong; Bang, Sunbaek; Choe, Eunyoung; Lippincott, Lee

    2009-05-15

    The mechanisms of perchlorate adsorption on activated carbon (AC) and anion exchange resin (SR-7 resin) were investigated using Raman, FTIR, and zeta potential analyses. Batch adsorption and desorption results demonstrated that the adsorption of perchlorate by AC and SR-7 resin was reversible. The reversibility of perchlorate adsorption by the resin was also proved by column regeneration test. Solution pH significantly affected perchlorate adsorption and the zeta potential of AC, while it did not influence perchlorate adsorption and the zeta potential of resin. Zeta potential measurements showed that perchlorate was adsorbed on the negatively charged AC surface. Raman spectra indicated the adsorption resulted in an obvious position shift of the perchlorate peak, suggesting that perchlorate was associated with functional groups on AC at neutral pH through interactions stronger than electrostatic interaction. The adsorbed perchlorate on the resin exhibited a Raman peak at similar position as the aqueous perchlorate, indicating that perchlorate was adsorbed on the resin through electrostatic attraction between the anion and positively charged surface sites.

  9. Silver nanoparticle incorporation effect on mechanical and thermal properties of denture base acrylic resins.

    Science.gov (United States)

    Köroğlu, Ayşegül; Şahin, Onur; Kürkçüoğlu, Işın; Dede, Doğu Ömür; Özdemir, Tonguç; Hazer, Baki

    2016-01-01

    The aim of the present study was to evaluate the mechanical and thermal characteristics of two denture base acrylic resins containing silver nanoparticles (AgNPs). Two different acrylic denture base resins (heat-polymerized and microwave polymerized) containing 0.3, 0.8 and 1.6 wt% AgNPs were evaluated for flexural strength, elastic modulus and impact strength. The glass transition temperature (Tg) and relative heat capacity (Cp) of the samples were determined from the Differential Scanning Calorimetry (DSC) results. For statistical analysis, two-way ANOVA and Tukey-HSD tests were performed. Addition of 0.8% and 1.6% AgNPs in microwave-polymerized resin significantly decreased the transverse strength and elastic modulus. In terms of impact strength, the addition of AgNPs has no effect on both resin groups. Glass transition temperature (Tg) was decreased with the addition of AgNPs for both denture base resins. The incorporation of AgNPs, generally used for antimicrobial efficiency, affected the transverse strength of the denture base acrylic resins depending on the concentration of nanoparticles. Tg was decreased with the addition of AgNPs for both denture base resins.

  10. Boswellia gum resin/chitosan polymer composites: Controlled delivery vehicles for aceclofenac.

    Science.gov (United States)

    Jana, Sougata; Laha, Bibek; Maiti, Sabyasachi

    2015-01-01

    This study was undertaken to evaluate the effect of Boswellia gum resin on the properties of glutaraldehyde (GA) crosslinked chitosan polymer composites and their potential as oral delivery vehicles for a non-steroidal anti-inflammatory drug, aceclofenac. The incorporation of resinous material caused a significant improvement in drug entrapment efficiency (∼40%) of the polymer composites. Fourier transform infrared (FTIR) spectroscopic analysis confirmed the formation of chitosan-gum resin composites and did not show any evidence of drug-polymer chemical interaction. Field emission scanning electron microscopy (FE-SEM) suggested the formation of particulate polymer composites up to chitosan:gum resin mass ratio of 1:3. Only 8-17% drug was released into HCl solution (pH 1.2) in 2h. The drug release rate of polymer composites was faster in phosphate buffer solution (pH 6.8). The composites released ∼60-68% drug load in 7h. In same duration, the drug release rate suddenly boosted up to 92% as the concentration of gum resin in the composites was raised to 80%. The drug release mechanism deviated from non-Fickian to case-II type with increasing resin concentration in the composites. Hence, GA-treated Boswellia resin-chitosan composites could be considered as alternative vehicles for oral delivery of aceclofenac. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Simulated localized wear of resin luting cements for universal adhesive systems with different curing mode.

    Science.gov (United States)

    Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Watanabe, Hidehiko; Johnson, William W; Latta, Mark A; Miyazaki, Masashi

    2018-01-29

    This study evaluated the simulated localized wear of resin luting cements for universal adhesive systems using different curing modes. Five resin luting cements for universal adhesive systems were evaluated and subsequently subjected to wear challenge in a Leinfelder-Suzuki wear simulation device. Overall, 20 specimens from each resin luting cement were photo-cured for 40 s (dual-cure group), and 20 specimens of each material were not photo-cured (chemical-cure group). Simulated localized wear was generated using a stainless steel ball-bearing antagonist in water slurry of polymethylmethacrylate beads. In addition, scanning electron microscopy (SEM) observations of resin luting cements and wear facets were conducted. Significant differences in simulated wear and SEM observations of wear facets were evident among the materials in the dual- and chemical-cure groups. The simulated wear and SEM observations of wear facets of G-CEM LinkForce and Panavia V5 were not influenced by the curing mode. SEM observations of resin luting cements were material dependent. In most cases, dual curing appears to ensure greater wear resistance of resin luting cements than chemical curing alone. The wear resistance of some resin luting cements appears to be material dependent and is not influenced by the curing mode.

  12. Flowsheet Validation For The Permanganate Digestion Of REILLEX(trademark) HPQ Anion Resin

    International Nuclear Information System (INIS)

    Kyser, E.

    2009-01-01

    The flowsheet for the digestion of Reillex(trademark) HPQ was validated both under the traditional alkaline conditions and under strongly acidic conditions. Due to difficulty in performing a pH adjustment in the large tank where this flowsheet must be performed, the recommended digestion conditions were changed from pH 8-10 to 8 M HNO 3 . Thus, no pH adjustment of the solution is required prior to performing the permanganate addition and digestion and the need to sample the digestion tank to confirm appropriate pH range for digestion may be avoided. Neutralization of the acidic digestion solution will be performed after completion of the resin digestion cycle. The amount of permanganate required for this type of resin (Reillex(trademark) HPQ) was increased from 1 kg/L resin to 4 kg/L resin to reduce the amount of residual resin solids to a minimal amount ( 2 ) solids (1.71 kg/L resin) and involves the generation of a significant liquid volume due to the low solubility of permanganate. However, since only two batches of resin (40 L each) are expected to be digested, the total waste generated is limited.

  13. Influence of the vacuum resin process, on the ballistic behaviour of lightweight armouring solutions

    Science.gov (United States)

    Lefebvre, M.; Boussu, F.; Coutellier, D.; Vallee, D.

    2012-08-01

    The armour of vehicles against conventional threats is mainly composed with steel or aluminium panels. Efficient heavy solutions exist, but the involved industries require new lightweight structures. Moreover, unconventional threats as IEDs (Improvised Explosive Devices) may cause severe damages on these structural and protective panel solutions. Thus, combination of aluminium or steel plates with textile composite structures used as a backing, leads to the mass reduction and better performance under delamination behaviour against these new threats. This paper is a part of a study dealing with the impact behaviour of three warp interlocks weaving structures under Fragment Simulating Projectile (FSP) impact. During this research, several parameters has being studied as the influence of the yarns insertions [1-4], the degradation of the yarns during the weaving process [5-7], and the influence of the resin rate on the ballistic behaviour. The resin rate inside composite materials is dependant on the final application. In ballistic protection, we need to control the resin rate in order to have a deformable structure in order to absorb the maximum of energy. However, with the warp interlocks weaving structure, the yarns insertions induce empty spaces between the yarns where the resin takes place without being evacuated. The resin rate inside the warp interlocks structures is in the most of cases less than 50%, which lead to have brittle and hard material during the impact. Contrary to interlocks structures, the existing protection based on prepreg structure have a high fibres ratio around 88% of weight. That leads to have the best ballistic properties during the impact and good deformability of the structure. The aim of this paper is to evaluate the influence of the resin rate on the ballistic results of the composites materials. For that, we have chosen two kinds of warp interlocks fabrics which were infused with epoxy resin following two processes. The first is a

  14. Influence of the vacuum resin process, on the ballistic behaviour of lightweight armouring solutions

    Directory of Open Access Journals (Sweden)

    Coutellier D.

    2012-08-01

    Full Text Available The armour of vehicles against conventional threats is mainly composed with steel or aluminium panels. Efficient heavy solutions exist, but the involved industries require new lightweight structures. Moreover, unconventional threats as IEDs (Improvised Explosive Devices may cause severe damages on these structural and protective panel solutions. Thus, combination of aluminium or steel plates with textile composite structures used as a backing, leads to the mass reduction and better performance under delamination behaviour against these new threats. This paper is a part of a study dealing with the impact behaviour of three warp interlocks weaving structures under Fragment Simulating Projectile (FSP impact. During this research, several parameters has being studied as the influence of the yarns insertions [1–4], the degradation of the yarns during the weaving process [5–7], and the influence of the resin rate on the ballistic behaviour. The resin rate inside composite materials is dependant on the final application. In ballistic protection, we need to control the resin rate in order to have a deformable structure in order to absorb the maximum of energy. However, with the warp interlocks weaving structure, the yarns insertions induce empty spaces between the yarns where the resin takes place without being evacuated. The resin rate inside the warp interlocks structures is in the most of cases less than 50%, which lead to have brittle and hard material during the impact. Contrary to interlocks structures, the existing protection based on prepreg structure have a high fibres ratio around 88% of weight. That leads to have the best ballistic properties during the impact and good deformability of the structure. The aim of this paper is to evaluate the influence of the resin rate on the ballistic results of the composites materials. For that, we have chosen two kinds of warp interlocks fabrics which were infused with epoxy resin following two

  15. Gold Loading on Ion Exchange Resins in Non-Ammoniacal Resin-Solution Systems

    Directory of Open Access Journals (Sweden)

    Abrar Muslim

    2010-12-01

    Full Text Available The loading of gold using strong base anion exchange resin in non-ammoniac resin-solution (NARS systems has been studied. The loading of gold onto ion exchange resins is affected by polythionate concentration, and trithionate can be used as the baseline in the system. The results also show that resin capacity on gold loading increases due to the increase in the equilibrium thiosulfate concentration in the NARS system. Gold loading performances show the need of optimization the equilibrium concentrations of thiosulfate in the NARS system. Keywords: equilibrium, gold loading, resin capacity, thiosulfate, trithionate

  16. Polyimide Resins Resist Extreme Temperatures

    Science.gov (United States)

    2009-01-01

    Spacecraft and aerospace engines share a common threat: high temperature. The temperatures experienced during atmospheric reentry can reach over 2,000 F, and the temperatures in rocket engines can reach well over 5,000 F. To combat the high temperatures in aerospace applications, Dr. Ruth Pater of Langley Research Center developed RP-46, a polyimide resin capable of withstanding the most brutal temperatures. The composite material can push the service temperature to the limits of organic materials. Designed as an environmentally friendly alternative to other high-temperature resins, the RP-46 polyimide resin system was awarded a 1992 "R&D 100" award, named a "2001 NASA Technology of the Year," and later, due to its success as a spinoff technology, "2004 NASA Commercial Invention of the Year." The technology s commercial success also led to its winning the Langley s "Paul F. Holloway Technology Transfer Award" as well as "Richard T. Whitcom Aerospace Technology Transfer Award" both for 2004. RP-46 is relatively inexpensive and it can be readily processed for use as an adhesive, composite, resin molding, coating, foam, or film. Its composite materials can be used in temperatures ranging from minus 150 F to 2,300 F. No other organic materials are known to be capable of such wide range and extreme high-temperature applications. In addition to answering the call for environmentally conscious high-temperature materials, RP-46 provides a slew of additional advantages: It is extremely lightweight (less than half the weight of aluminum), chemical and moisture resistant, strong, and flexible. Pater also developed a similar technology, RP-50, using many of the same methods she used with RP-46, and very similar in composition to RP-46 in terms of its thermal capacity and chemical construction, but it has different applications, as this material is a coating as opposed to a buildable composite. A NASA license for use of this material outside of the Space Agency as well as

  17. The solidification of spent resin

    International Nuclear Information System (INIS)

    Shiao, S. J.; Tsai, C. M.; Shyu, Y. H.

    1991-01-01

    A quasi-steady apparatus was applied to measure the thermal conductivity of solids ranging in size for 0.3 to 200 L, and temperature distributions in the solids were recorded during the curing, and theoretical equation for conduction in a cylindrical form with uniform energy generation was established to define the thermal state of reaction. The heat of reaction calculated from the theoretical equation with experimental values for the maximum temperature and thermal conductivity agrees very well with the data reported. The relationships among heat of reaction and amount of curing agent, retardant, loading of spent resin, and water were established

  18. Development of metal-resin composite for dental magnet keepers, Part 2: Optimum 4-META content.

    Science.gov (United States)

    Soma, Hiroko; Miyagawa, Yukio

    2011-01-01

    Six kinds of experimental magnetic resin composites containing SUS447J1 stainless steel particles as filler were prepared. UDMA/MAA resin with an MAA mole fraction of 0.67 was used as the matrix resin. The effects of six levels of 4-META content (2, 4, 6, 8, 10, and 12 mass%) on the setting and flexural properties were studied. The metal filler content in each paste was 90 mass%. Although working time and setting time significantly diminished with the increase of the BPO and DMPT contents, both working time and setting time satisfied the ISO 4049 requirements for all experimental levels. Flexural strength and elastic modules significantly improved with the increase of 4-META content up to 10%. The optimum 4-META content necessary to develop better composite resins for magnetic attachment has been clarified.

  19. Do flexible acrylic resin lingual flanges improve retention of mandibular complete dentures?

    Science.gov (United States)

    Ahmed Elmorsy, Ayman Elmorsy; Ahmed Ibraheem, Eman Mostafa; Ela, Alaa Aboul; Fahmy, Ahmed; Nassani, Mohammad Zakaria

    2015-01-01

    The aim of this study was to compare the retention of conventional mandibular complete dentures with that of mandibular complete dentures having lingual flanges constructed with flexible acrylic resin "Versacryl." The study sample comprised 10 completely edentulous patients. Each patient received one maxillary complete denture and two mandibular complete dentures. One mandibular denture was made of conventional heat-cured acrylic resin and the other had its lingual flanges made of flexible acrylic resin Versacryl. Digital force-meter was used to measure retention of mandibular dentures at delivery and at 2 weeks and 45 days following denture insertion. The statistical analysis showed that at baseline and follow-up appointments, retention of mandibular complete dentures with flexible lingual flanges was significantly greater than retention of conventional mandibular dentures (P dentures, retention of dentures increased significantly over the follow-up period (P acrylic resin lingual flanges in the construction of mandibular complete dentures improved denture retention.

  20. Experimental and Theoretical Studies of Moisture and Temperature Effects on the Mechanical Properties of Graphite/Epoxy Laminates and Neat Resins

    Science.gov (United States)

    Sternstein, S. S.

    1984-01-01

    The properties of high performnce composites which are strongly dependent on the physical properties of the matrix resin were studied. Moisture adversely affect the properties of both neat epoxy resin and epoxy matrix composites. Inhomogeneous swelling as to the moisture degradation of mechanical properties, both in the neat resin and the composite. It is postulated that the postcuring process can change structure/moisture interactions and partially alleviate its adverse effects. The study is directed toward are understanding of the physical/mechanical/thermodynamic aspects of this problem.

  1. Comparison of Cashew Nut Shell Liquid (CNS Resin with Polyester Resin in Composite Development

    Directory of Open Access Journals (Sweden)

    C. C. Ugoamadi

    2013-12-01

    Full Text Available Natural resins can compete effectively with the synthetic ones in composite development. In this research, cashew nuts were picked and processed for the extraction of the resin content. The resin (natural resin so obtained was mixed with cobalt amine (accelerator, methyl ethyl ketone peroxide (catalyst to develop two sets of composite specimens – specimens without fibres and specimens reinforced with glass fibres. This method of sample specimen development was repeated with polyester (synthetic resin. Compressive and tensile strength tests conducted proved that composites developed with cashew nut shell liquid (CNSL resin were comparable to those developed with polyester resin. In the results, CNSL has an ultimate compressive strength of 55MPa compared to that of polyester resin with an ultimate strength of 68MPa. The result of tensile strength proved cashew nut shell liquid resin (with ultimate strength of 44MPa to be better than polyester resin with 39MPa as ultimate tensile strength. This means that natural resins could be a better substitute for the synthetic ones when the required quantities of fibers (reinforcements and fillers are used in the fibre-reinforced plastic composite developments.

  2. Fissure sealant materials: Wear resistance of flowable composite resins.

    Science.gov (United States)

    Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

    2016-01-01

    Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm(2) and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm(2)of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

  3. Fissure sealant materials: Wear resistance of flowable composite resins

    Directory of Open Access Journals (Sweden)

    Sohrab Asefi

    2016-08-01

    Full Text Available Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow, Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists. A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm2 and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm2of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

  4. resin as polymer-supported synthesis support

    Indian Academy of Sciences (India)

    Administrator

    dichloro-5,6-dicyano- benzoqunone ... ports used most widely in SPOS are Merrifield resin .... (2 × 10 mL). The resin was dried at 50°C for one hour to give white beads. IR (KBr): 3108, 3312 cm–1. 1H-NMR (500 MHz, CDCl3): δ 7⋅13 (br s, PS), 7⋅01.

  5. [Delayed asthma bronchiale due to epoxy resin].

    Science.gov (United States)

    Authried, Georg; Al-Asadi, Haifaa; Møller, Ulla; Sherson, David Lee

    2013-10-28

    Epoxy resin is a low molecular weight agent, which can cause both acute and delayed allergic reactions. However, it is known causing skin reactions with direct or airborne contact. Rarely it can cause airway reactions like asthma bronchiale. We describe a case of a windmill worker who developed delayed asthma bronchiale due to airborne contact with epoxy resin.

  6. Epoxidation of linseed oil-Alkyd resins

    International Nuclear Information System (INIS)

    Motawie, A.M.; Ismail, E.A.; Mazroua, A.M.; Abd EI Aziem, M.S.; Ramadan, A.M.

    2004-01-01

    Three types of different linseed oil-alkyd resin ( Alk (I), Alk (II), and Alk (III) ) were prepared with the calculated amounts of mono glycerides and adipic acid (1:1, 1:2, and 2:1 Eq.Wt) respectively via monoglyceride method. The obtained alkyd resins were epoxidized via reaction with the calculated quantities of peracetic acid, which was prepared by the reaction of acetic anhydride with H 2 O 2 . Epoxidation occurred with the ratio (1: 1, 1 :3, and 1:6 Eq. Wt) of alkyd to peracetic acid. The effect of reaction time on the epoxy group content was measured during the epoxidation process. The prepared alkyd resins were analyzed by IR and H 1 NMR. The metal coated film properties of epoxidized alkyd resins were compared with those of unmodified alkyd resins. It was observed that the coating films of epoxidized alkyd resins have better in drying properties, hardness, adhesion, impact and flexibility than those of un epoxidized alkyd resins. The flammability properties of the paper coated films for the prepared brominated epoxidized alkyd resins were found to be fire retardant

  7. Facile synthesis of hypercrosslinked resins via chloromethylation ...

    Indian Academy of Sciences (India)

    A sort of non-polystyrene type hypercrosslinked resin was firstly synthesized through chloromethylation of simple aryl molecules (benzene, toluene, naphthalene, diphenyl), succedent continuous Friedel–Crafts alkylation polymerization and post-crosslinking reaction. The chemical and porous structures of these novel resins ...

  8. Aging of Organic Matrices, Epoxy Resins; Causas de envejecimiento de matrices organicas. Resinas epoxidicas

    Energy Technology Data Exchange (ETDEWEB)

    Pazos, M.; Prendes, P.; Varela, M.; Paz, S. [Departamento de I mas D de Gairesa, La Coruna (Spain)

    1997-09-01

    Epoxy resins are very important polymers widely used in advance materials. Approximately 200.000 Tns/year are used in different fields such as coating, floor and paving, adhesives, composites, etc. Due to the importance of these polymers, aging studies are necessary. In this work most important aging-factors are described. We have observed that the water plays a very important role in the degradation-process. (Author)

  9. In vitro evaluation of failure loads of nonmetal cantilevered resin-bonded fixed dental prostheses.

    Science.gov (United States)

    van Dalen, Andy; Feilzer, Albert J; Kleverlaan, Cornelis J

    2008-12-01

    To evaluate in vitro the influence of fiber reinforcement on the failure loads of resin composite beams, simulating cantilevered two-unit resin-bonded fixed dental prostheses, and compare the results with similarly obtained failure loads of ZrO2 and CoCr beams of a comparable design. Peel tests were performed using resin composite, fiber-reinforced resin composite, and zirconia beams, simulating two-unit cantilevered resin-bonded fixed dental prostheses, luted with Panavia F2.0 onto flat-ground buccal surfaces of bovine mandibular incisors. The recorded failure loads were compared with those of CoCr beams of a similar size and design from earlier research. Finite element analysis revealed the stress concentrations within the cement layers at failure. The failure loads (N) of the peel tests, depending on the beam type and including the type of failure, were statistically analyzed. The highest failure values were obtained with the fiber-reinforced resin composite beams, which were luted with the exposed fibers directly on the bovine enamel. Finite element analysis showed that peak stress locations depend on the beam type and facilitate the explanation of the different failure modes. Fiber-reinforcement of simulated two-unit cantilevered resin composite resin-bonded fixed dental prostheses does not necessarily lead to higher failure loads. This study identified significant differences in peel failure loads between identical specimens, depending on whether or not the fiber reinforcement was exposed on the luting surface. Further research needs to be carried out regarding the combination of resin composite and fiber reinforcement.

  10. Microtensile bond strengths to cavity floor dentin in indirect composite restorations using resin coating.

    Science.gov (United States)

    Okuda, Makoto; Nikaido, Toru; Maruoka, Rena; Foxton, Richard M; Tagami, Junji

    2007-01-01

    The aims of this study were (1) to evaluate the effect of a resin coating on the microtensile bond strengths (mu-TBSs) of indirect composite restorations bonded to dentin with resin cement and (2) to compare the mu-TBSs with that of a directly placed composite. Class I cavities were prepared in extracted human molars. The specimens were divided into five groups: For the indirect restorations, the cavity surfaces of the control group were left uncoated (group 1), while the surfaces of the experimental groups were resin coated with a dentin bonding system, Clearfil Protect Bond (PB; groups 2 and 3), or with a combination of PB and a flowable resin composite, Protect Liner F (PLF; group 4). The cavities were temporized for 1 day. Indirect composite restorations (Estenia) were cemented with a resin cement (Panavia F). Pretreatment with ED Primer II was performed in the groups 1, 3, and 4. For the direct restorations, the cavities were restored with PB and a direct composite (Clearfil AP-X; group 5). After 24 hours of water storage, mu-TBSs were measured at a crosshead speed of 1 mm/min. The data were analyzed with one-way analysis of variance and Sheffe's test (p resin coating consisting of a self-etching primer dentin bonding system and a flowable resin composite significantly improved the mu-TBS of indirect restorations bonded to dentin using resin cement. A resin coating should be required to improve dentin bonding performance of Panavia F in indirect restorations. However, direct composite restorations still provide higher bond strength compared to indirect restorations.

  11. Power density of various light curing units through resin inlays with modified layer thickness

    Directory of Open Access Journals (Sweden)

    Sung-Ok Hong

    2012-08-01

    Full Text Available Objectives The purpose of this study was to enhance curing light penetration through resin inlays by modifying the thicknesses of the dentin, enamel, and translucent layers. Materials and Methods To investigate the layer dominantly affecting the power density of light curing units, resin wafers of each layer with 0.5 mm thickness were prepared and power density through resin wafers was measured with a dental radiometer (Cure Rite, Kerr. The dentin layer, which had the dominant effect on power density reduction, was decreased in thickness from 0.5 to 0.1 mm while thickness of the enamel layer was kept unchanged at 0.5 mm and thickness of the translucent layer was increased from 0.5 to 0.9 mm and vice versa, in order to maintain the total thickness of 1.5 mm of the resin inlay. Power density of various light curing units through resin inlays was measured. Results Power density measured through 0.5 mm resin wafers decreased more significantly with the dentin layer than with the enamel and translucent layers (p < 0.05. Power density through 1.5 mm resin inlays increased when the dentin layer thickness was reduced and the enamel or translucent layer thickness was increased. The highest power density was recorded with dentin layer thickness of 0.1 mm and increased translucent layer thickness in all light curing units. Conclusions To enhance the power density through resin inlays, reducing the dentin layer thickness and increasing the translucent layer thickness would be recommendable when fabricating resin inlays.

  12. Flexural Strength of Cold and Heat Cure Acrylic Resins Reinforced with Different Materials

    Science.gov (United States)

    Heidari, Bijan; Firouz, Farnaz; Izadi, Alireza; Ahmadvand, Shahbaz

    2015-01-01

    Objectives: Heat-polymerized acrylic resin has been the most commonly used denture base material for over 60 years. However, the mechanical strength of acrylic resin is not adequate for long-term clinical performance of dentures. Consequently, fracture is a common clinical occurrence, which often develops in the midline of the denture base. This study aimed to evaluate the efficacy of cold-cure and heat-cure acrylic resins, reinforced with glass fibers, polyethylene fibers, and metal wire for denture base repair. Materials and Methods: Ninety specimens were prepared and allocated to nine groups. Ten specimens were considered as controls, and 80 were divided into 8 experimental groups. In the experimental groups, the specimens were sectioned into two halves from the middle, and were then divided into two main groups: one group was repaired with heat cure acrylic resin, and the other with cold cure acrylic resin. Each group was divided into 4 subgroups: unreinforced, reinforced with glass fibers, polyethylene fibers, and metal wire. All specimens were subjected to a 3-point bending test, and the flexural strength was calculated. Results: The group repaired with heat cure acrylic resin and reinforced with glass fiber showed the highest flexural strength; however, the group repaired with cold cure acrylic resin and reinforced with polyethylene fibers had the lowest flexural strength. There was no significant difference between the groups repaired with heat cure and cold cure acrylic resins without reinforcement. Conclusion: Repairing denture base with heat cure acrylic resin, reinforced with glass fibers increases the flexural strength of denture base. PMID:26877726

  13. Flexural Strength of Cold and Heat Cure Acrylic Resins Reinforced with Different Materials

    Directory of Open Access Journals (Sweden)

    Bijan Heidari

    2015-10-01

    Full Text Available Objectives: Heat-polymerized acrylic resin has been the most commonly used denture base material for over 60 years. However, the mechanical strength of acrylic resin is not adequate for long-term clinical performance of dentures. Consequently, fracture is a com- mon clinical occurrence, which often occurs in the midline of denture base.This study aimed to evaluate the efficacy of cold cure and heat cure acrylic resins, rein- forced with glass fibers, polyethylene fibers, and metal wire for denture base repair.Materials and Methods: Ninety specimens were prepared and allocated to nine groups. Ten specimens were included in the control group, and 80 were allocated to 8 experi- mental groups. In the experimental groups, the specimens were sectioned into two halves from the middle, and were then divided into two main groups: one group was repaired with heat cure acrylic resin, and the other with cold cure acrylic resin. Each group was di- vided into 4 subgroups: unreinforced, reinforced with glass fibers, polyethylene fibers, and metal wire. All specimens were then subjected to a 3-point bending test, and the flexural strength was calculated.Results: The group repaired with heat cure acrylic resin and reinforced with glass fiber showed the highest flexural strength; however, the group repaired with cold cure acrylic resin and reinforced with polyethylene fibers had the lowest flexural strength. There was no significant difference between the groups repaired with heat cure and cold cure acrylic resins without reinforcement.Conclusion: Repairing denture base with heat cure acrylic resin, reinforced with glass fi- bers increases the flexural strength of denture base.

  14. Effect of polishing systems on stain susceptibility and surface roughness of nanocomposite resin material.

    Science.gov (United States)

    Barakah, Haifa M; Taher, Nadia M

    2014-09-01

    Different polishing systems vary in their effect on reducing surface roughness and stain susceptibility of dental composite resin materials. The purpose of this study was to compare the effect of 3 polishing systems on the stain susceptibility and surface roughness of 2 nanocomposite resins and a microhybrid composite resin. Forty-five disks (2×10 mm) each were fabricated of 2 nanocomposite resins (Filtek Supreme XT and Tetric EvoCeram) and 1 microhybrid composite resin (Z250). Both sides of the disks were wet finished, and 1 side was polished with PoGo, Astropol, or Hi-Shine (n=5). Unpolished surfaces served as controls. The average roughness (Ra, μm) was measured with a profilometer, and the baseline color was recorded with a spectrophotometer. All specimens were incubated while soaking in a staining solution of coffee, green tea, and berry juice for 3 weeks. The color was recorded again, and the data were analyzed with 2-way ANOVA at α=.05 and Tukey multiple comparison tests. All polishing systems improved the staining resistance of Filtek Supreme XT and Z250 but did not affect that of Tetric EvoCeram. The surface color of Filtek Supreme XT was changed significantly and was the smoothest after polishing with PoGo, whereas Hi-Shine produced significantly rougher surfaces but with the lowest color change. Hi-Shine produced the highest color change in Z250. The surface roughness did not differ significantly between the other polishing systems. Tetric EvoCeram showed no significant differences in color change or surface roughness. Staining susceptibility and surface roughness depend mainly on material composition and on the polishing procedures. Polishing improves the staining resistance of composite resins. Nanocomposite resins did not exhibit better staining resistance or surface roughness than microhybrid composite resin. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  15. Effect of incorporating BisGMA resin on the bonding properties of silane and zirconia primers.

    Science.gov (United States)

    Chen, Liang; Shen, Hong; Suh, Byoung In

    2013-11-01

    Some silane primers and some zirconia primers contain extra resins such as bisphenol A glycol dimethacrylate (BisGMA) in their formulations for better wetting. No studies exist on the bonding properties of zirconia and silane primers, which contain extra resins. The purpose of this study was to investigate the effect of incorporating BisGMA resin on the bonding properties of silane and zirconia primers. Silica-base lithium disilicate was etched and treated with BisGMA-incorporated Porcelain Primer, unmodified Porcelain Primer, or resin-containing Kerr Silane. Zirconia ceramic was airborne-particle abraded and treated with BisGMA-incorporated Monobond Plus, unmodified Monobond Plus, or BisGMA-containing ZPrime Plus. After primer treatment and cleaning with ethanol, the contact angles were measured to determine surface change (n=10). Shear bond strength tests were also performed to measure the adhesion strength between resin cements and ceramic surfaces (n=10). Data were statistically analyzed by 1-way ANOVA followed by the Tukey multiple comparison as a post hoc test (significance level .05). The incorporation of BisGMA resin did not significantly influence the bond strength or contact angle of the zirconia primer (P>.05), but it did significantly reduce those of the silane primer (PSilane (22 degrees, 23 MPa) had a similar contact angle and higher bond strength than the control (21 degrees, 18 MPa), but lower than Porcelain Primer (88 degrees, 34 MPa). Resin-containing ZPrime Plus (75 degrees, 29 MPa) had a similar contact angle and higher bond strength than both Monobond Plus (74 degrees, 18 MPa) and the control (15 degrees, 4 MPa). The addition of BisGMA resin significantly inhibited the efficacy of silane-containing porcelain primers but did not affect that of phosphate-containing zirconia primers. Copyright © 2013 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  16. Physical Properties of Synthetic Resin Materials

    Science.gov (United States)

    Fishbein, Meyer

    1939-01-01

    A study was made to determine the physical properties of synthetic resins having paper, canvas, and linen reinforcements, and of laminated wood impregnated with a resin varnish. The results show that commercial resins have moduli of elasticity that are too low for structural considerations. Nevertheless, there do exist plastics that have favorable mechanical properties and, with further development, it should be possible to produce resin products that compare favorably with the light-metal alloys. The results obtained from tests on Compound 1840, resin-impregnated wood, show that this material can stand on its own merit by virtue of a compressive strength four times that of the natural wood. This increase in compressive strength was accomplished with an increase of density to a value slightly below three times the normal value and corrected one of the most serious defects of the natural product.

  17. Embedding of reactor wastes in plastic resins

    International Nuclear Information System (INIS)

    1979-01-01

    STEAG Kernenergie GmbH is so far the only firm commercially to condition radioactive bead ion exchange resins by embedding in polystyrene resins. The objective of the work reported here was to study and develop methods for immobilization of other reactor wastes in plastic resins. Comparison studies on high quality cement however showed favourable results for cement with respect to process safety and economy. For this reason STEAG interrupted its work in the field of resin embedding after about one year. The work carried out during this period is surveyed in this report, which includes a comprehensive literature study on reactor wastes and their solidification in plastic resins as well as on regulations with regard to radioactive waste disposal in the member states of the European Communities

  18. Disinfection of denture base acrylic resin.

    Science.gov (United States)

    Lin, J J; Cameron, S M; Runyan, D A; Craft, D W

    1999-02-01

    During repair or adjustments of acrylic resin removable complete and partial dentures, particles of the acrylic resin from the interior of the prosthesis may expose dental personnel to microbial health hazards if the prosthesis has not been thoroughly disinfected. This study investigates the efficacy of a commercially prepared microbial disinfectant (Alcide) on the external and internal surfaces of acrylic resins. Four groups of acrylic resin were incubated in an experimental model to simulate the oral environment over time. Specimens were treated in 2 groups, disinfected and not disinfected, and then further grouped by breaking and not breaking. Analysis was performed with microbial colony counts, SEM, and statistical analyses. Viable microorganisms still remain on the internal and external surfaces of treated resins. Chlorine dioxide reduces, but does not eliminate, viable microorganisms on these dental prostheses.

  19. The influence of powder liquid ratio on the flexural strength of fibre reinforced acrylic resin material.

    Science.gov (United States)

    Geerts, G A V M; du Rand, M

    2009-04-01

    Often the powder liquid (P/L) ratio of polymethyl methacrylate (PMMA) resins is changed to modify the handling properties of the material. While it is known that this may influence the mechanical properties of unreinforced PMMA resin, little is known about its effect on fibre reinforced resin. The purpose of this study was to determine how different P/L ratios influence the flexural strength (FS) of a glass fibre reinforced autopolymerizing PMMA resin used for fabricating fixed partial dentures. Two main groups of PMMA resin, 1 unreinforced and 1 reinforced with glass fibre, had 3 subgroups (n=21) each representing a different P/L ratio. The manufacturer's recommended ratio served as control. The specimens were prepared for a 3-point bending test. Using a universal testing machine, maximum force was recorded and the FS was calculated. Median FS values were compared by means of non-parametric analysis of variance (Kruskal-Wallis). A p-value of less than 0.05 was considered significant. FS values of all reinforced subgroups were significantly higher than the values of the unreinforced subgroups (p0.05). Within the reinforced group there was a significant difference between the control group, which had a higher median FS value than the two other subgroups (presin with glass fibre, it is important to use the recommended P/L ratio. For unreinforced PMMA resin the P/L ratio can be changed within limits without adverse effects on the FS.

  20. Effect of light curing sources on microhardness of different composite resins

    Science.gov (United States)

    Valentino, T. A.; Calabrez-Filho, S.; de Menezes, F. C. H.; Cavalcante, L. M. A.; Pimenta, L. A. F.; de Andrade, M. F.; Dantas, A. A. R.; Rastelli, A. N. S.

    2011-06-01

    This study evaluated the influence of light-curing units (LCUs) on Knoop microhardness (KHN) of different composite resins formulations. Four LCUs, one Quartz-Tungsten-Halogen (QTH) for 20 s, one Argon-Ion-Laser (AL) for 10 s, one Plasma-Arc-Curing (PAC) for 9 s, and one Light-Emitting-Diode (LED) for 20 s, and three composite resins, nanofill and easy cure (Filtek™ Supreme), microhybrid and medium cure (Herculite XRV), and microfill and difficult cure (Heliomolar) were used. Discs (4 × 2 mm2) of each composite resin were divided in 12 Groups and KHN was measured at the top (T) and bottom (B) surfaces. Data were analyzed using two-way ANOVA and Tukey's test ( p < 0.05). Top presented significantly higher KHN than bottom surface for all composite resins and LCUs tested. Statistical significant differences were observed among the LCUs. At the bottom surface QTH and LED presented higher KHN than PAC and LA. However, at the top surface PAC and LA presented similar results than QTH for nanofill and microhybrid composite resins. Different LCUs play an important effect on Knoop microhardness and the composite resin formulations were significant factor on the photosensitivity.

  1. Factors affecting marginal integrity of class II bulk-fill composite resin restorations

    Science.gov (United States)

    Savadi Oskoee, Siavash; Bahari, Mahmoud; Jafari Navimipour, Elmira; Ajami, Amir Ahmad; Ghiasvand, Negar; Savadi Oskoee, Ayda

    2017-01-01

    Background. Bulk-fill composite resins are a new type of resin-based composite resins, claimed to have the capacity to be placed in thick layers, up to 4 mm. This study was carried out to evaluate factors affecting gap formation in Cl II cavities restored using the bulk-fill technique. Methods. A total of 60 third molars were used in this study. Two Cl II cavities were prepared in each tooth, one on the mesial aspect 1 mm coronal to the CEJ and one on the distal aspect 1 mm apical to the CEJ. The teeth were divided into 4 groups: A: The cavities were restored using the bulk-fill technique with Filtek P90 composite resin and its adhesive system and light-cured with quartz tungsten halogen (QTH) light-curing unit. B: The cavities were restored similar to that in group A but light-cured with an LED light-curing unit. C: The cavities were restored using the bulk-fill technique with X-tra Fil composite resin and Clearfil SE Bond adhesive system and light-cured with a QTH curing unit. D: The cavities were restored similar to that in group C but light-cured with an LED light-curing unit. The gaps were examined under a stereomicroscope at ×60. Data were analyzed with General Linear Model test. In cases of statistical significance (Pcomposite resin type and margin location (Pcomposite resin type were not significant; however, the cumulative effect of composite rein type*gingival margin was significant (P=0.04) Conclusion. X-tra Fil composite exhibited smaller gaps compared with Filtek P90 composite with both light-curing units. Both composite resins exhibited smaller gaps at enamel margins. PMID:28748051

  2. The effect of repeated preheating of dimethacrylate and silorane-based composite resins on marginal gap of class V restorations.

    Science.gov (United States)

    Alizadeh Oskoee, Parnian; Pournaghi Azar, Fatemeh; Jafari Navimipour, Elmira; Ebrahimi Chaharom, Mohammad Esmaeel; Naser Alavi, Fereshteh; Salari, Ashkan

    2017-01-01

    Background. One of the problems with composite resin restorations is gap formation at resin‒tooth interface. The present study evaluated the effect of preheating cycles of silorane- and dimethacrylate-based composite resins on gap formation at the gingival margins of Class V restorations. Methods. In this in vitro study, standard Class V cavities were prepared on the buccal surfaces of 48 bovine incisors. For restorative procedure, the samples were randomly divided into 2 groups based on the type of composite resin (group 1: di-methacrylate composite [Filtek Z250]; group 2: silorane composite [Filtek P90]) and each group was randomly divided into 2 subgroups based on the composite temperature (A: room temperature; B: after 40 preheating cycles up to 55°C). Marginal gaps were measured using a stereomicroscope at ×40 and analyzed with two-way ANOVA. Inter- and intra-group comparisons were analyzed with post-hoc Tukey tests. Significance level was defined at P composite resin type, preheating and interactive effect of these variables on gap formation were significant (Pcomposite resins (Pcomposite resins at room temperature compared to composite resins after 40 preheating cycles (Pcomposite re-sins. Preheating of silorane-based composites can result in the best marginal adaptation.

  3. Evaluation of Resin-Resin Interface in Direct Composite Restoration Repair

    Science.gov (United States)

    Stoleriu, S.; Andrian, S.; Pancu, G.; Nica, I.; Iovan, G.

    2017-06-01

    The aim of this study was to evaluate the resin-resin interface when a universal bonding agent was used in two different strategies in direct restoration repair. Two composite resins (a micro-filled hybrid and a nano-filled hybrid) as old restorations that have to be repair, a universal bonding agent and a micro-filled hybrid composite resin (different then that aged) as new material for repair were chosen for the study. Non-aged samples were used as control and aged samples were used as study groups. The universal bonding agent was applied in etch-and-rinse and in self-etch strategies. The interface between old and new composite resins was evaluated by SEM and the microleakage was assessed by scoring the dye penetration. Very good adaptation of the two different composite resins placed in direct contact in non-aged samples was recorded. No gaps or defects were visible and strong resin-resin contact was observed. After aging, enlargement of resin-resin junction were observed in most of the samples and a increased dye penetration was recorded irrespective of the strategy (etch-and-rinse or self-etch) used for bonding agent application.

  4. Bond strength of a chairside autopolymerizing reline resin to injection-molded thermoplastic denture base resins.

    Science.gov (United States)

    Hamanaka, Ippei; Shimizu, Hiroshi; Takahashi, Yutaka

    2017-01-01

    This study evaluated the shear bond strength of a chairside autopolymerizing reline resin to injection-molded thermoplastic denture base resins. Four kinds of injection-molded thermoplastic resins (two polyamides, a polyethylene terephthalate copolymer and a polycarbonate) and PMMA, as a control, were tested. The eight types of surface treatment: ((1) no treatment, (2) air abrasion, (3) dichloromethane, (4) ethyl acetate, (5) 4-META/MMA-TBB resin, (6) air abrasion and 4-META/MMA-TBB resin, (7) tribochemical silica coating, and (8) tribochemical silica coating and 4-META/MMA-TBB resin) were applied to each specimen. The chairside autopolymerizing reline resins were bonded to disks of the injection-molded thermoplastic denture base resins. All of the specimens were immersed in water for 4 months and then thermocycled for 10,000 cycles in water between 5 and 55°C. The shear bond strengths were determined. The shear bond strengths of the two polyamides treated using air abrasion, dichloromethane and ethyl acetate and no treatment were exceedingly low. The greatest bond strength was recorded for the polyethylene terephthalate copolymer specimens treated with tribochemical silica coating and 4-META/MMA-TBB resin (22.5MPa). The bond strengths of the other injection-molded thermoplastic denture base resins increased using 4-META/MMA-TBB resin. Tribochemical silica coating and 4-META/MMA-TBB resin were the most effective surface treatments among all denture base resins tested. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  5. Properties of halloysite nanotube-epoxy resin hybrids and the interfacial reactions in the systems

    Energy Technology Data Exchange (ETDEWEB)

    Liu Mingxian; Guo Baochun; Du Mingliang; Cai Xiaojia; Jia Demin [Department of Polymer Materials and Engineering, South China University of Technology, Guangzhou 510640 (China)

    2007-11-14

    A naturally occurred microtubullar silicate, halloysite nanotubes (HNTs), was co-cured with epoxy/cyanate ester resin to form organic-inorganic hybrids. The coefficient of thermal expansion (CTE) of the hybrids with low HNT concentration was found to be substantially lower than that of the plain cured resin. The moduli of the hybrids in the glassy state and rubbery state were significantly higher than those for the plain cured resin. The dispersion of HNTs in the resin matrix was very uniform as revealed by the transmission electron microscopy (TEM) results. The interfacial reactions between the HNTs and cyanate ester (CE) were revealed by the results of Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). The substantially increased properties of the hybrids were attributed to the covalent bonding between the nanotubes and the matrix.

  6. Properties of halloysite nanotube epoxy resin hybrids and the interfacial reactions in the systems

    Science.gov (United States)

    Liu, Mingxian; Guo, Baochun; Du, Mingliang; Cai, Xiaojia; Jia, Demin

    2007-11-01

    A naturally occurred microtubullar silicate, halloysite nanotubes (HNTs), was co-cured with epoxy/cyanate ester resin to form organic-inorganic hybrids. The coefficient of thermal expansion (CTE) of the hybrids with low HNT concentration was found to be substantially lower than that of the plain cured resin. The moduli of the hybrids in the glassy state and rubbery state were significantly higher than those for the plain cured resin. The dispersion of HNTs in the resin matrix was very uniform as revealed by the transmission electron microscopy (TEM) results. The interfacial reactions between the HNTs and cyanate ester (CE) were revealed by the results of Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). The substantially increased properties of the hybrids were attributed to the covalent bonding between the nanotubes and the matrix.

  7. Influence of curing rate on softening in ethanol, degree of conversion, and wear of resin composite

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Peutzfeldt, Anne; Asmussen, Erik

    2011-01-01

    PURPOSE: To investigate the effect of curing rate on softening in ethanol, degree of conversion, and wear of resin composites. METHOD: With a given energy density and for each of two different light-curing units (QTH or LED), the curing rate was reduced by modulating the curing mode. Thus......, the irradiation of resin composite specimens (Filtek Z250, Tetric Ceram, Esthet-X) was performed in a continuous curing mode and in a pulse-delay curing mode. Wallace hardness was used to determine the softening of resin composite after storage in ethanol. Degree of conversion was determined by infrared...... spectroscopy (FTIR). Wear was assessed by a three-body test. Data were submitted to Levene's test, one and three-way ANOVA, and Tukey HSD test (alpha = 0.05). Results: Immersion in ethanol, curing mode, and material all had significant effects on Wallace hardness. After ethanol storage, resin composites...

  8. Durability of a low shrinkage TEGDMA/HEMA-free resin composite system in Class II restorations

    DEFF Research Database (Denmark)

    van Dijken, Jan WV; Pallesen, Ulla

    2017-01-01

    Objective: The objective of this randomized controlled prospective trial was to evaluate the durability of a low shrinkage and TEGDMA/HEMA-free resin composite system in posterior restorations in a 6-year follow up. Material and methods: 139 Class II restorations were placed in 67 patients...... with a mean age of 53 years (range 29-82). Each participant received at random two, as similar as possible, Class II restorations. In the first cavity of each pair the TEGDMA/HEMA-free resin composite system was placed with its 3-step etch-and-rinse adhesive (cmf-els). In the second cavity a 1-step HEMA...... for failure were fracture followed by recurrent caries. Most fractures and all caries lesions were found in high risk participants. Significance: The tested Class II resin composite restorations performed with the new TEGDMA/HEMA-free low shrinkage resin composite system showed good durability over six years....

  9. Trifunctional Epoxy Resin Composites Modified by Soluble Electrospun Veils: Effect on the Viscoelastic and Morphological Properties

    Directory of Open Access Journals (Sweden)

    Giulia Ognibene

    2018-03-01

    Full Text Available Electrospun veils from copolyethersulfones (coPES were prepared as soluble interlaminar veils for carbon fiber/epoxy composites. Neat, resin samples were impregnated into coPES veils with unmodified resin, while dry carbon fabrics were covered with electrospun veils and then infused with the unmodified epoxy resin to prepare reinforced laminates. The thermoplastic content varied from 10 wt% to 20 wt%. TGAP epoxy monomer showed improved and fast dissolution for all the temperatures tested. The unreinforced samples were cured first at 180 °C for 2 h and then were post-cured at 220 °C for 3 h. These sample showed a high dependence on the curing cycle. Carbon reinforced samples showed significant differences compared to the neat resin samples in terms of both viscoelastic and morphological properties.

  10. The effect of light-cured nanofilled composite resin shades on their under-surface temperature

    Science.gov (United States)

    Hanum, U. A.; Herda, E.; Indrani, D. J.

    2017-08-01

    The objective of this study was to observe the effect of shades of light-cured nanofilled composite resins on their under-surface temperature. Resin composites specimens of shades bright, medium, and dark shade were obtained from a cylindrical mold. While polymerizing using a curing unit, the under-surface temperature was determined at the bottom of the specimens using a thermocouple wire 20 sec after the start. Results showed that the under-surface temperature of the darker shade specimens were relatively higher that those of the brighter shades with significant diffferences between the resin composites of different shades. To conlude, the under-surface temperature of the light-cured nanofilled resin composites raised from the brighter to the darker shades.

  11. Chemical reactivation of quenched fluorescent protein molecules enables resin-embedded fluorescence microimaging

    Science.gov (United States)

    Xiong, Hanqing; Zhou, Zhenqiao; Zhu, Mingqiang; Lv, Xiaohua; Li, Anan; Li, Shiwei; Li, Longhui; Yang, Tao; Wang, Siming; Yang, Zhongqin; Xu, Tonghui; Luo, Qingming; Gong, Hui; Zeng, Shaoqun

    2014-06-01

    Resin embedding is a well-established technique to prepare biological specimens for microscopic imaging. However, it is not compatible with modern green-fluorescent protein (GFP) fluorescent-labelling technique because it significantly quenches the fluorescence of GFP and its variants. Previous empirical optimization efforts are good for thin tissue but not successful on macroscopic tissue blocks as the quenching mechanism remains uncertain. Here we show most of the quenched GFP molecules are structurally preserved and not denatured after routine embedding in resin, and can be chemically reactivated to a fluorescent state by alkaline buffer during imaging. We observe up to 98% preservation in yellow-fluorescent protein case, and improve the fluorescence intensity 11.8-fold compared with unprocessed samples. We demonstrate fluorescence microimaging of resin-embedded EGFP/EYFP-labelled tissue block without noticeable loss of labelled structures. This work provides a turning point for the imaging of fluorescent protein-labelled specimens after resin embedding.

  12. Determination of the effective anticandidal concentration of denture cleanser tablets on some denture base resins

    Directory of Open Access Journals (Sweden)

    Yeliz Hayran

    2018-01-01

    Full Text Available Abstract Objective Although the effectiveness of chemical cleansing against Candida albicans biofilm has been shown, the effective concentration of denture cleanser tablets has not been studied. The aim of this study was to assess the effect of three denture materials against Candida albicans biofilm and to determine effective concentrations of denture cleanser tablets. Material and methods The surface-roughness of Acron-hi™, QC-20™ and Deflex™ (n=45 per resin resins was standardized by using a profilometer and their contact angle or surface free energy was calculated. C. albicans biofilm was formed on all three resins and were treated with Polident 3 min™, Corega™ and Fittydent™ cleanser solutions at various concentrations and both resin-biofilm and cleanser-biofilm interest were determined by using a MTT protocol according to the European Committee on Antimicrobial Susceptibility Testing's antifungal susceptibility testing (AFST-EUCAST. Scanning electron microscopy was used to compare the efficacy of different resin materials against C. albicans biofilm. Anticandidal activity and surface free energy statistical parameters were calculated by using 3-way and 1-way ANOVA, respectively (p<0.05. Results Polident 3 min™ and Corega™ tablets significantly inhibited (p<0.05 the proliferation of C. albicans against all denture resins at 27-37 mg/mL. Scanning electron microscopy results indicated that there was no significant difference among resin specimens regarding biofilm formation on dentures. We failed to find a significant relationship between surface free energy and the anticandidal effect of resin types. However, the polarity value of the resins was statistically associated with their anticandidal activity. Conclusions The polarity of the resins, the concentrations of tablets and the chemical content of the cleanser may directly affect C. albicans biofilm formations. Polident 3 min™ and Corega™ tablets should be suggested for

  13. Twelve-year survival of 2-surface composite resin and amalgam premolar restorations placed by dental students.

    Science.gov (United States)

    Naghipur, Safa; Pesun, Igor; Nowakowski, Anthony; Kim, Aaron

    2016-09-01

    Composite resin and amalgam restorations are indicated for the restoration of posterior teeth. With increased esthetic demands, long-term clinical studies are required to evaluate the restorative success and reasons for failure of these materials. The purpose of this retrospective study was to determine the survival and reasons for failure of directly placed 2-surface composite resin restorations and directly placed 2-surface amalgam restorations on premolars placed by Canadian dental students. Using The University of Manitoba's dental management software and paper charts, all 2-surface composite resin and 2-surface amalgam restorations placed on premolars between January 1, 2002, and May 30, 2014, were included. Short-term failure (within 2 years), long-term failure, and reasons for failure were collected. A Kaplan-Meier survival estimate with an associated P value comparing composite resin to amalgam restoration curves was performed using SPSS statistical software. Over 12 years, 1695 composite resin and 1125 amalgam 2-surface premolar restorations were placed. Of these restorations, 134 composite resins (7.9%) and 66 amalgams (5.9%) failed. Short-term failures (2 years or less) consisted of 57 composite resin (4%) and 23 amalgam (2.3%) restorations. Long-term failures (greater than 2 years) consisted of 77 composite resin (4.5%) and 43 amalgam (3.8%) restorations. After 12 years of service, the survival probability of composite resin restorations was 86% and that of amalgam restorations 91.5%. The differences in composite resin and amalgam survival curves were also found to be statistically significant (P=.009 for Log-rank test). The main reasons for failure were recurrent caries and fracture of the tooth being restored. Within the limitations of this study, both composite resin and amalgam restorations had acceptable success rates and similar failure modes. Recurrent caries was still the most common reason for failure. Copyright © 2016 Editorial Council for

  14. Evaluation of leachable behavior from ion exchange resins effects of organic impurities on BWR water chemistry. 1

    International Nuclear Information System (INIS)

    Igarashi, Hiroo; Nishimura, Yusaku; Ohsumi, Katsumi; Uchida, Shunsuke; Matsui, Tsuneo

    1999-01-01

    The elution rate of leachables from ion exchange resin, which is used in condensate demineralizers and is one of several major sources of organic compounds in BWR cooling water, was measured. Properties of the leachables and elution rate depended on the kind of ion exchange resin and the years of use. The organic compounds elution rate of cation exchange resin was constant for 5 years and the molecular weight of these leachables was low. After 5 years, the elution rate increased and leachables consisted of organic compounds of high molecular weights of several thousand. The elution rate of anion exchange resin decreased yearly. The difference in the elution behavior was attributed to a dependence on oxidation degradation promoted by transition metal catalysis. The cation exchange resin included absorbed transition metal, while the anion exchange resin did not. An empirical formula showing the time dependence of the elution rate of organic compounds was derived. The formula was judged to be appropriate based on simulations of an actual BWR plant and comparisons of impurity concentrations with actual reactor water data. (author)

  15. Mineralogy of fossil resins in Northern Eurasia

    Science.gov (United States)

    Bogdasarov, M. A.

    2007-12-01

    The investigation is focused on identification and origin of fossil resins from the Cretaceous, Tertiary, and Quaternary sediments of Northern Eurasia on the basis of detailed study of their physical and chemical characteristics: morphology; size; mass; density; optical, mechanical, and thermal properties; chemical composition; etc. The composition of amorphous organic minerals with polymeric structure, fossil resins included, is studied with IR spectrometry, the EPR method, derivatography at low heating rates, XRD, chemical analysis, emission spectrometry, etc. The results of investigation summarized for the Baltic-Dnieper, North Siberian, and Far East amber-bearing provinces show some similarity of fossil resins in combination with specific features inherent to each province. Resins from the Baltic-Dnieper province should be termed as amber (succinite). Their variety is the most characteristic of Northern and Eastern Europe. Amber-like fossil resins from the North Siberian and Far East provinces are irrelevant to succinite. They usually occur as brittle resins, namely, retinite and gedanite, without jewelry value. Viscous fossil resin rumänite with an expected high economic value occurs in the Far East, on the shore of Sakhalin Island.

  16. Investigation of fossil resins and amber

    Directory of Open Access Journals (Sweden)

    E.Yu. Makarova

    2017-05-01

    Full Text Available Fossil resins and amber are a product of lithogenesis of resinous substances of higher plants – resinite. These components of plants, like other lipoid ingredients (suberins, coutines, sporinins, natural rubbers are resistant to microbial action, so they are well preserved in bacterial processing of organic matter in the stages of sedimento- and diagenesis, and are well diagnosed in microscopic studies. They occur in a rather wide age range of sedimentary rocks. The amber of the Baltic region of the Eocene age is most fully studied. The article presents the results of a study of the collection of fossil resins and amber from various regions of the world. Samples were studied microscopically; carbon isotope analysis, infrared spectroscopy (IR spectroscopy were performed. The most informative analysis of high-molecular polymeric compounds is IR spectroscopy. It was found that in the analyzed samples of fossil resins of different ages, aromatic compounds are not observed, most of which are first volatilized in fossilization processes. The possibility of influencing the group composition of amber and amber-like resins for sedimentation, diagenesis and catagenesis is discussed. The IR spectra of fossil and modern resin conifers are compared. Using the IR spectroscopy method, an attempt was made to identify the botanical origin of fossil resins.

  17. Effects of polishing procedures on color stability of composite resins.

    Science.gov (United States)

    Güler, Ahmet Umut; Güler, Eda; Yücel, Ali Cağin; Ertaş, Ertan

    2009-01-01

    The purpose of this study was to investigate the effect of different polishing methods on color stability of posterior, universal and nanohybrid composite resin restorative materials upon exposure to a staining agent. Twenty-five specimens were prepared for each of 5 different composite resins (Filtek Z250, Filtek P60, Quadrant LC, Grandio and Filtek Supreme). Specimens were divided into 5 groups and different polishing procedures, including polishing discs (Pd), polishing discs then diamond polishing paste (PdP), polishing discs then a liquid polishing system (Biscover) (PdB), and combinations of these (PdPB) were used. Unpolished specimens served as the control (C). The specimens were stored for 48 h in a coffee solution. The color of all specimens was measured before and after exposure with a colorimeter, and total color change (DeltaE*) were calculated. The data were analyzed with a two-way ANOVA and the means were compared by Tukey HSD test (alpha=0.05). The lowest color difference was observed in the groups PdP and C, while the highest color difference was observed in PdPB, and PdB. When comparing the five different restorative materials, no significant difference was observed between FiltekP60 and FiltekZ250, and these materials demonstrated significantly less color change than Quadrant LC and the nanohybrid materials (Grandio, Filtek Supreme). The posterior (Filtek P60) and universal (Filtek Z250) composite resin restorative materials, which do not contain tetraethyleneglycol dimethacrylate (TEGDMA), were found to be less stainable than the nanohybrid (Grandio, Filtek Supreme) and universal (Quadrant LC) composite resins, which contain TEGDMA. The use of diamond polishing paste after polishing with polishing discs significantly decreased staining when compared to the groups that used polishing discs alone, for all restorative materials tested. The highest color change values were obtained for the specimens that were polished with the Biscover liquid polish

  18. Effects of polishing procedures on color stability of composite resins

    Directory of Open Access Journals (Sweden)

    Ahmet Umut Güler

    2009-04-01

    Full Text Available The purpose of this study was to investigate the effect of different polishing methods on color stability of posterior, universal and nanohybrid composite resin restorative materials upon exposure to a staining agent. Twenty-five specimens were prepared for each of 5 different composite resins (Filtek Z250, Filtek P60, Quadrant LC, Grandio and Filtek Supreme. Specimens were divided into 5 groups and different polishing procedures, including polishing discs (Pd, polishing discs then diamond polishing paste (PdP, polishing discs then a liquid polishing system (Biscover (PdB, and combinations of these (PdPB were used. Unpolished specimens served as the control (C. The specimens were stored for 48 h in a coffee solution. The color of all specimens was measured before and after exposure with a colorimeter, and total color change (DE* were calculated. The data were analyzed with a two-way ANOVA and the means were compared by Tukey HSD test (a=0.05. The lowest color difference was observed in the groups PdP and C, while the highest color difference was observed in PdPB, and PdB. When comparing the five different restorative materials, no significant difference was observed between FiltekP60 and FiltekZ250, and these materials demonstrated significantly less color change than Quadrant LC and the nanohybrid materials (Grandio, Filtek Supreme. The posterior (Filtek P60 and universal (Filtek Z250 composite resin restorative materials, which do not contain tetraethyleneglycol dimethacrylate (TEGDMA, were found to be less stainable than the nanohybrid (Grandio, Filtek Supreme and universal (Quadrant LC composite resins, which contain TEGDMA. The use of diamond polishing paste after polishing with polishing discs significantly decreased staining when compared to the groups that used polishing discs alone, for all restorative materials tested. The highest color change values were obtained for the specimens that were polished with the Biscover liquid polish

  19. Flexural strength of acrylic resins polymerized by different cycles

    Directory of Open Access Journals (Sweden)

    Débora Barros Barbosa

    2007-10-01

    Full Text Available Despite the large number of studies addressing the effect of microwave polymerization on the properties of acrylic resin, this method has received limited clinical acceptance. This study evaluated the influence of microwave polymerization on the flexural strength of a denture base resin. A conventional heat-polymerized (Clássico, a microwave-polymerized (Onda-Cryl and a autopolymerizing acrylic (Jet resins were used. Five groups were established, according to polymerization cycles: A, B and C (Onda-Cryl, short cycle - 500W/3 min, long - 90W/13 min + 500W/90 sec, and manufacturing microwave cycle - 320W/3 min + 0W/3 min + 720W/3 min; T (Clássico, water bath cycle - 74ºC/9h and Q (Jet, press chamber cycle - 50ºC/15 min at 2 bar. Ten specimens (65 x 10 x 3.3mm were prepared for each cycle. The flexural strength of the five groups was measured using a three-point bending test at a cross-head speed of 5 mm/min. Flexural strength values were analyzed by one-way ANOVA and the Tukey's test was performed to identify the groups that were significantly different at 5% level. The microwave-polymerized groups showed the highest means (p<0.05 for flexural strength (MPa (A = 106.97 ± 5.31; B = 107.57 ± 3.99; C = 109.63 ± 5.19, and there were no significant differences among them. The heat-polymerized group (T showed the lowest flexural strength means (84.40 ± 1.68, and differ significantly from all groups. The specimens of a microwavable denture base resin could be polymerized by different microwave cycles without risk of decreasing the flexural strength.

  20. Mechanical properties of composite resin blocks for CAD/CAM.

    Science.gov (United States)

    Lauvahutanon, Sasipin; Takahashi, Hidekazu; Shiozawa, Maho; Iwasaki, Naohiko; Asakawa, Yuya; Oki, Meiko; Finger, Werner J; Arksornnukit, Mansuang

    2014-01-01

    This study compared commercial composite resin blocks with one ceramic block for use in computer-aided design/computer aided manufacturing (CAD/CAM). Four composite resins, one composite ceramic, and one feldspar-ceramic block were investigated. Flexural strength (FS), flexural modulus (FM), and Vickers hardness (VH) were determined under three conditions: dry storage; immersion in water at 37°C for 7 days; and immersion in water at 37°C for 7 days followed by 10,000 thermocycles. After dry storage, FS ranged from 127 to 242 MPa, FM from 9.6 to 51.5 GPa, and VH from 64 to 455. Two-way ANOVA was performed for FS, FM and VH followed by Tukey's multiple comparison (α<0.05). Results demonstrated that the materials degraded after water immersion and thermocycling, but their properties were within the acceptable range for fabrication of single restorations according to the ISO standard for ceramics (ISO 6872:2008).

  1. Effect of siloxane quantity and ph of silane coupling agents and contact angle of resin bonding agent on bond durability of resin cements to machinable ceramic.

    Science.gov (United States)

    Meng, Xiangfeng; Yoshida, Keiichi; Taira, Yohsuke; Kamada, Kohji; Luo, Xiaoping

    2011-02-01

    The aim of this study was to measure siloxane quantity, pH value, and resin wettability on ceramics silanized by five silane coupling agents, and to test the correlation of these parameters of silane coupling agents with bond durability between a machinable glass ceramic and resin cements. 1.5-mm-thick ceramic plates (ProCAD, Ivoclar Vivadent) were polished, cleaned, and bonded with ten combinations of five silane coupling agents (Monobond S [Ivoclar Vivadent], Rely X Ceramic Primer [3M], Clearfil Ceramic Primer [Kuraray], GC Ceramic Primer [GC], Porcelain Liner M [Sun Medical]) and two dual-curing resin cements (VariolinkII [VLII, Ivoclar Vivadent], Linkmax HV [LMHV, GC]). Their microshear bond strength was measured after 0, 10,000, and 30,000 thermal cycles. Siloxane quantity, pH value of silane coupling agents and contact angle of Heliobond (Ivoclar Vivadent) to silanized ceramic were measured using a FTIR spectrophotometer, pH-indicator strips, and a contact-angle meter, respectively. Bond strength data were analyzed by three-way ANOVA. For each cement, Pearson's correlation coefficient was calculated to analyze possible correlation between bond strength under different thermocycling conditions and absorbance peak of siloxane, pH value of silane coupling agents, and contact angle of resin to the silanized ceramic surface. The bond strength of ceramic was significantly influenced by the silane coupling agent and thermal cycles, not by resin cement. For both cements, only a negative correlation was found to be significant between the contact angle of resin to silanized ceramic surfaces and bond strength after 30,000 thermal cycles. The better the wettability of resin on different silanized ceramic surfaces could improve their bond durability.

  2. Effect of conditioning solutions containing ferric chloride on dentin bond strength and collagen degradation.

    Science.gov (United States)

    Rodrigues, Raquel Viana; Giannini, Marcelo; Pascon, Fernanda Miori; Panwar, Preety; Brömme, Dieter; Manso, Adriana Pigozzo; Carvalho, Ricardo Marins

    2017-10-01

    To investigate the effects of conditioning solutions containing ferric chloride (FeCl 3 ) on resin-dentin bond strength; on protection of dentin collagen against enzymatic degradation and on cathepsin-K (CT-K) activity. Conditioning solutions were prepared combining citric acid (CA) and anhydrous ferric chloride (FeCl 3 ) in different concentrations. The solutions were applied to etch flat dentin surfaces followed by bonding with adhesive resin. Phosphoric acid (PA) gel etchant was used as control. The microtensile bond strength (μTBS) was tested after 24h of storage in water and after 9 months of storage in phosphate buffer saline. Dentin slabs were demineralized in 0.5M EDTA, pre-treated or not with FeCl 3 and incubated with CT-K. The collagenase activity on dentin collagen matrix was examined and characterized by SEM. Additional demineralized dentin slabs were treated with the conditioning solutions, and the amount of Fe bound to collagen was determined by EDX. The activity of CT-K in the presence of FeCl 3 was monitored fluorimetrically. Data were analyzed by ANOVA followed by post-hoc tests as required (α=5%). Slightly higher bond strengths were obtained when dentin was conditioned with 5% CA/0.6% FeCl 3 and 5% CA-1.8%FeCl 3 regardless of storage time. Bond strengths reduced significantly for all tested conditioners after 9 months of storage. Treating dentin with 1.8% FeCl 3 was effective to preserve the structure of collagen against CT-K. EDX analysis revealed binding of Fe-ions to dentin collagen after 15s immersion of demineralized dentin slabs into FeCl 3 solutions. FeCl 3 at concentration of 0.08% was able to suppress CT-K activity. This study shows that FeCl 3 binds to collagen and offers protection against Cat-K degradation. Mixed solutions of CA and FeCl 3 may be used as alternative to PA to etch dentin in resin-dentin bonding with the benefits of preventing collagen degradation. Copyright © 2017 The Academy of Dental Materials. Published by

  3. Assessment of the flexural strength of two heat-curing acrylic resins for artificial eyes.

    Science.gov (United States)

    Fernandes, Aline Ursula Rocha; Portugal, Aline; Veloso, Letícia Rocha; Goiato, Marcelo Coelho; Santos, Daniela Micheline dos

    2009-01-01

    Prosthetic eyes are artificial substitutes for the eyeball, made of heat-curing acrylic resin, serving to improve the esthetic appearance of the mutilated patient and his/her inclusion in society. The aim of this study was to assess the flexural strength of two heat-curing acrylic resins used for manufacturing prosthetic eyes. Thirty-six specimens measuring 64 x 10 x 3.3 mm were obtained and divided into four groups: acrylic resin for artificial sclera N1 (Artigos Odontológicos Clássico, São Paulo, SP, Brazil), heat-cure water technique (GI) and microwave-cured (GII); colorless acrylic resin for prosthetic eyes (Artigos Odontológicos Clássico, São Paulo, SP, Brazil), heat-cure water technique (GIII) and microwave-cured (GIV). Mechanical tests using three point loads were performed in a test machine (EMIC, São José dos Pinhais, PR, Brazil). The analysis of variance and the Tukey test were used to identify significant differences (p < 0.01). Groups GII and GIV presented, respectively, the highest (98.70 +/- 11.90 MPa) and lowest means (71.07 +/- 8.93 MPa), with a statistically significant difference. The cure method used for the prosthetic eye resins did not interfere in their flexural strength. It was concluded that all the resins assessed presented sufficient flexural strength values to be recommended for the manufacture of prosthetic eyes.

  4. Effect of autoclave postpolymerization treatments on the fracture toughness of autopolymerizing dental acrylic resins.

    Science.gov (United States)

    Durkan, Rukiye; Gürbüz, Ayhan; Yilmaz, Burak; Özel, M Birol; Bağış, Bora

    2012-06-26

    Microwave and water bath postpolymerization have been suggested as methods to improve the mechanical properties of heat and autopolymerizing acrylic resins. However, the effects of autoclave heating on the fracture properties of autopolymerizing acrylic resins have not been investigated. The aim of this study was to assess the effectiveness of various autoclave postpolymerization methods on the fracture properties of 3 different autopolymerizing acrylic resins. Forty-two specimens of 3 different autopolymerizing acrylic resins (Orthocryl, Paladent RR and Futurajet) were fabricated (40x8x4mm), and each group was further divided into 6 subgroups (n=7). Control group specimens remained as processed (Group 1). The first test group was postpolymerized in a cassette autoclave at 135°C for 6 minutes and the other groups were postpolymerized in a conventional autoclave at 130°C using different time settings (5, 10, 20 or 30 minutes). Fracture toughness was then measured with a three-point bending test. Data were analyzed by ANOVA followed by the Duncan test (α=0.05). The fracture toughness of Orthocryl and Paladent-RR acrylic resins significantly increased following conventional autoclave postpolymerization at 130°C for 10 minutes (Pautoclave postpolymerized Futurajet was not significantly different than its control specimens (Pautoclaved at 130°C for 10 minutes. Within the limitations of this study, it can be suggested that autoclave postpolymerization is an effective method for increasing the fracture toughness of tested autoploymerized acrylic resins.

  5. Effect of two abrasive systems on resin bonding to laboratory-processed indirect resin composite restorations.

    Science.gov (United States)

    Bouschlicher, M R; Cobb, D S; Vargas, M A

    1999-01-01

    This study compared two methods of surface roughening or preparation, with or without the use of proprietary surface wetting agents, to evaluate their effect on resin cement adhesion to the following laboratory-processed, indirect restorations: Artglass (AG), belleGlass HP (BG), Concept (C), and Targis (T). Methods of surface roughening or preparation included microetching with aluminum oxide (AO): 50 microns at 34 psi and silanized silica coating, CoJet-Sand (CJ): 30 microns at 34 psi. Artglass and Concept were tested with and without the use of their respective surface wetting agents: Artglass Liquid (AGL) and Special Bond II (SB). One hundred twenty specimens, each consisting of a pair of cylinders (7.0 x 3 mm and 4.3 x 3 mm) were fabricated. The larger cylinder or base was embedded in self-curing resin in a phenolic ring, and bonding surfaces were finished with 320-grit silicon carbide paper. Specimen pairs for each restorative material were randomly assigned to treatment groups (n = 10) and received the following surface treatments prior to cementation: group 1 (AG/AO/+AGL), group 2 (AG/AO/-AGL), group 3 (AG/CJ/+AGL), group 4 (AG/CJ/-AGL), group 5 (BG/AO), group 6 (BG/CJ), group 7 (C/AO/+SB), group 8 (C/AO/-SB), group 9 (C/CJ/+SB), group 10 (C/CJ/-SB), group 11 (T/AO), and group 12 (T/CJ). Specimen pairs were cemented with a dual-cure resin cement (Dual) and a standardized force of 1 MPa. Specimens were light-cured 40 seconds per side (80 s total), then thermocycled 300 times at between 5 degrees and 55 degrees C. Shear bond strengths (MPa) were determined using a Zwick Materials Testing Machine at a crosshead speed of 5 mm per minute. One-way analysis of variance (ANOVA) and Duncan's multiple range test (alpha = 0.05) by restoration type indicated no significant differences in shear bond strength between BG group 5 (29.8 +/- 5.8), BG group 6 (28.3 +/- 4.3), T group 11 (29.3 +/- 4.9), and T group 12 (29.0 +/- 4.4). Shear bond strength in AG group 3 (35.9 +/- 3

  6. Melamine-modified urea formaldehyde resin for bonding particleboards

    Science.gov (United States)

    Chung-Yun Hse; Feng Fu; Hui Pan

    2008-01-01

    For the development of a cost-effective melamine-modified urea formaldehyde resin (MUF), the study evaluated the effects of reaction pH and melamine content on resin properties and bond performance of the MUF resin adhesive systems. Eight resins, each with three replicates, were prepared in a factorial experiment that included two formulation variables: two reaction...

  7. Traumatic resin ducts as indicators of bark beetle outbreaks

    Science.gov (United States)

    R. Justin DeRose; Matthew F. Bekker; James N. Long

    2017-01-01

    The formation of traumatic resin ducts (TRDs) represents an important induced defense in woody plants that enhances oleoresin production and flow in response to environmental perturbations. In some genera (Pinus), resin ducts are copious and conspicuous; however, in others (Picea), resin ducts are relatively rare. The occurrence and strength of resin ducts, in...

  8. Resin replica in enamel deproteinization and its effect on acid etching.

    Science.gov (United States)

    Espinosa, Roberto; Valencia, Roberto; Uribe, Mario; Ceja, Israel; Cruz, J; Saadia, Marc

    2010-01-01

    The goal of this in vitro study was to identify the topographical features of deproteinized (NaOCl) and etched with phosphoric acid (H3PO4) enamel surface, compared to phosphoric acid surface alone with a Resin Replica model. Ten extracted lower first and second permanent molars were polished with pumice and water, and then divided into 3 equal buccal sections having similar physical and chemical properties. The enamel surfaces of each group were subjected to the following treatments: Group A: Acid Etching with H3PO4 37% for 15 seconds. Group B: Sodium Hypochlorite (NaOCl) 5.25% for 60 seconds followed by Acid Etching with H3PO4 37% for 15 seconds. Group C; No treatment (control). All the samples were treated as follow: Adhesive and resin were applied to all groups after A, B and C treatment were performed; Then enamel/dentin decalcification and deproteinization and topographic SEM Resin Replica assessment were used to identify resin tags enamel surface quality penetration. Showed that group B reached an area of 7.52 mm of the total surface, with a 5.68 mm2 (73%) resin tag penetration equivalent type I and II etching pattern, 1.71 mm2 (26%) equivalent to type III etching pattern and 0.07 mm2 (1%) unaffected surface. Followed by group A with 7.48 mm2 of the total surface, with a 3.47 mm2 (46 %)resin tag penetration equivalent to type I and II etching pattern, 3.30 mm2 (45%)equivalent to type III etching pattern and 0.71 mm2, and (9%) unaffected surface. Group C did not show any resin tag penetration. A significant statistical diference (P enamel is deproteinizated with 5.25% NaOCl for 1 minute prior H3PO4, the surface and topographical features of the replica resin penetration surface increases significantly with type I-II etching pattern.

  9. Curing efficiency of various resin-based materials polymerized through different ceramic thicknesses and curing time

    Science.gov (United States)

    Lee, Jung-Won; Cha, Hyun-Suk

    2011-01-01

    PURPOSE The aim of this in vitro study was to examine the curing efficiency of various resin-based materials polymerized through ceramic restorations with 3 different thicknesses. Curing efficiency was evaluated by determining the surface microhardness (VHN) of the resin specimens. MATERIALS AND METHODS Four kinds of resin materials were used. Z350 (3M ESPE Filtek™ Z350: A2 Shade), Z250 (3M ESPE Filtek™ Z250: A2 Shade) and Variolink® II (VL: Ivoclar vivadent, base: transparent) either with or without a self-curing catalyst (VLC: Ivoclar vivadent, catalyst: low viscosity/transparent) were filled into the silicone mold (10 mm diameter, 1 mm thick). They were cured through ceramic discs (IPS e.max Press MO-0 ingot ivoclar vivadent, 10 mm diameter, 0.5, 1 and 2 mm thicknesses) by LED light-curing units for 20 and 40 seconds. Vicker's microhardness numbers (VHNs) were measured on the bottom surfaces by a microhardness tester. Data were analyzed using a 3- way analysis of variance (ANOVA) at a significance level of 0.05. RESULTS The thickness of ceramic disc increased, the VHNs of all four resin types were decreased (Plight cured for 40 seconds were significantly higher than that of LED for 20 seconds in all four resin materials (Pcuring time resulted higher VHN values of all resin materials. The use of a catalyst produced a greater hardness with all polymerization methods. Restorative resin materials (Z350, Z250) showed higher VHN values than resin cement materials (VL, VLC). PMID:22053242

  10. The effect of various frequencies of ultrasonic cleaner in reducing residual monomer in acrylic resin.

    Science.gov (United States)

    Charasseangpaisarn, Taksid; Wiwatwarrapan, Chairat

    2015-12-01

    Monomer remaining in denture base acrylic can be a major problem because it may cause adverse effects on oral tissue and on the properties of the material. The purpose of this study was to compare the effect of various ultrasonic cleaner frequencies on the amount of residual monomer in acrylic resin after curing. Forty-two specimens each of Meliodent heat-polymerized acrylic resin (M) and Unifast Trad Ivory auto-polymerized acrylic resin (U) were prepared according to their manufacturer's instructions and randomly divided into seven groups: Negative control (NC); Positive control (PC); and five ultrasonic treatment groups: 28 kHz (F1), 40 kHz (F2), 60 kHz (F3) (M=10 min, U=5 min), and 28 kHz followed by 60 kHz (F4: M=5 min per frequency, U=2.5 min per frequency, and F5: M=10 min followed by 5 min per frequency, U=5 min followed by 2.5 min per frequency). Residual monomer was determined by HPLC following ISO 20795-1. The data were analyzed by One-way ANOVA and Tukey HSD. There was significantly less residual monomer in the auto-polymerized acrylic resin in all ultrasonic treatment groups and the PC group than that of the NC group (pacrylic resin (p>0.05). The amount of residual monomer in heat-polymerized acrylic resin was significantly lower than that of auto-polymerized acrylic resin. In conclusion, ultrasonic treatment at low frequencies is recommended to reduce the residual monomer in auto-polymerized acrylic resin and this method is more practical in a clinical situation than previously recommended methods because of reduced chairside time. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. The influence of resin cements on the final color of ceramic veneers.

    Science.gov (United States)

    Chen, Xiao-Dong; Hong, Guang; Xing, Wen-Zhong; Wang, Yi-Ning

    2015-07-01

    To evaluate the effect of three brands of resin cement on the final color of ceramic veneers. 50 disk-shaped ceramic specimens (IPS e.Max, 0.6mm×8.0mm diameter) and disk-shaped composite resin background specimens (4.0mm×8.0mm diameter) were prepared and divided into 10 groups (n=5). These paired specimens were bonded using ten shades of resin cement (Variolink Veneer, shades LV-3, LV-2, MV, HV+2, HV+3; Panavia F, shades light and brown; and RelyX™ Veneer, shades WO, TR, A3). A spectrophotometer (VITA Easyshade) was used to measure the color parameters (CIE L*a*b* values) of the paired disks before and after cementation. The color differences (ΔE values) after cementation were calculated and statistically analyzed by the One-way ANOVA (at the significant level pceramic disks were measured in terms of the increase in L* value, and the decrease in Cab(*) value after bonding with the resin cement. The ΔE values of ceramic disks after cementation ranged from 1.38 to 7.16. The ΔE values were more than 3.3 when the ceramic disks were cemented with resin cements in shade HV+3 (4.90) and shade WO (7.16). One-way ANOVA of ΔE values revealed significant differences in the resin cement shades. Resin cements can affect the final color of ceramic veneer restorations, and the extent of this effect varies according to the resin cement shades. Copyright © 2015 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  12. Microbial community evolution of black and stinking rivers during in situ remediation through micro-nano bubble and submerged resin floating bed technology.

    Science.gov (United States)

    Sun, Yanmei; Wang, Shiwei; Niu, Junfeng

    2018-06-01

    Microbes play important roles during river remediation and the interaction mechanism illustration between microorganisms and sewage is of great significance to improve restoration technology. In this study, micro-nano bubble and submerged resin floating bed composite technology (MBSR) was firstly used to restore two black and stinking urban rivers. After restoration, the water pollution indices such as dissolved oxygen (DO), ammonia nitrogen (NH 4 + -N), total phosphorous (TP), chemical oxygen demand (COD Cr ), water clarity, and the number of facial coliform were significantly improved. Microbial community composition and relative abundance both varied and more aerobic microbes emerged after remediation. The microbial changes showed correlation with DO, NH 4 + -N, TP and COD Cr of the rivers. In summary, the MBSR treatment improved the physiochemical properties of the two black and stinking urban rivers probably through oxygen enrichment of micro-nano bubble and adsorption of submerged resin floating bed, which thereby stimulated functional microbes to degrade pollutants. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Recent Advances in Adhesive Bonding - The Role of Biomolecules, Nanocompounds, and Bonding Strategies in Enhancing Resin Bonding to Dental Substrates.

    Science.gov (United States)

    Münchow, Eliseu A; Bottino, Marco C

    2017-09-01

    To present an overview on the main agents (i.e., biomolecules and nanocompounds) and/or strategies currently available to amplify or stabilize resin-dentin bonding. According to studies retrieved for full text reading (2014-2017), there are currently six major strategies available to overcome resin-dentin bond degradation: (i) use of collagen crosslinking agents, which may form stable covalent bonds with collagen fibrils, thus strengthening the hybrid layer; (ii) use of antioxidants, which may allow further polymerization reactions over time; (iii) use of protease inhibitors, which may inhibit or inactivate metalloproteinases; (iv) modification of the bonding procedure, which may be performed by using the ethanol wet-bonding technique or by applying an additional adhesive (hydrophobic) coating, thereby strengthening the hybrid layer; (v) laser treatment of the substrate prior to bonding, which may cause specific topographic changes in the surface of dental substrates, increasing bonding efficacy; and (vi) reinforcement of the resin matrix with inorganic fillers and/or remineralizing agents, which may positively enhance physico-mechanical properties of the hybrid layer. With the present review, we contributed to the better understanding of adhesion concepts and mechanisms of resin-dentin bond degradation, showing the current prospects available to solve that problematic. Also, adhesively-bonded restorations may be benefited by the use of some biomolecules, nanocompounds or alternative bonding strategies in order to minimize bond strength degradation.

  14. Properties of a nanodielectric cryogenic resin

    Energy Technology Data Exchange (ETDEWEB)

    Polyzos, Georgios [ORNL; Tuncer, Enis [ORNL; Sauers, Isidor [ORNL; More, Karren Leslie [ORNL

    2010-01-01

    Physical properties of a nanodielectric composed of in situ synthesized titanium dioxide (TiO{sub 2}) nanoparticles ({le} 5 nm in diameter) and a cryogenic resin are reported. The dielectric losses were reduced by a factor of 2 in the nanocomposite, indicating that the presence of small TiO{sub 2} nanoparticles restricted the mobility of the polymer chains. Dielectric breakdown data of the nanodielectric was distributed over a narrower range than that of the unfilled resin. The nanodielectric had 1.56 times higher 1% breakdown probability than the resin, yielding 0.64 times thinner insulation thickness for the same voltage level, which is beneficial in high voltage engineering.

  15. SEM and elemental analysis of composite resins

    International Nuclear Information System (INIS)

    Hosoda, H.; Yamada, T.; Inokoshi, S.

    1990-01-01

    Twenty-four chemically cured, 21 light-cured anterior, three light-cured anterior/posterior, and 18 light-cured posterior composite resins were examined using scanning electron microscopy, and the elemental composition of their filler particles was analyzed with an energy dispersive electron probe microanalyzer. According to the results obtained, the composite resins were divided into five groups (traditional, microfilled type, submicrofilled type, hybrid type, and semihybrid), with two additional hypothetical categories (microfilled and hybrid). Characteristics of each type were described with clinical indications for selective guidance of respective composite resins for clinical use

  16. In-depth disinfection of acrylic resins.

    Science.gov (United States)

    Chau, V B; Saunders, T R; Pimsler, M; Elfring, D R

    1995-09-01

    This study demonstrated that bacteria penetrate three kinds of dental acrylic resin after a short time period. Samples of acrylic resin were contaminated with a variety of bacteria and were then placed in three different disinfecting solutions as directed by the manufacturers. After the specific dilution and immersion time, cultures were made from the resin samples. The only effective disinfectant was a 0.525% solution of sodium hypochlorite at a 10-minute immersion. It disinfected not only the surfaces but also the bacteria that penetrated the surfaces to a depth of 3 mm.

  17. Immobilisation of ion exchange resins in cement

    International Nuclear Information System (INIS)

    Howard, C.G.; Jolliffe, C.B.; Lee, D.J.

    1990-09-01

    The removal of activity from spent decontaminating solutions eg LOMI can be achieved using organic ion exchange resins. These resins can be successfully immobilised in cement based matrices. The optimum cement system contained 10% ordinary Portland cement 84% gg blast furnace slag, 6% microsilica with a water cement ratio of 0.5 and a dry resin loading of 36% with respect to total weight. This formulation was successfully scaled up to 200 litres giving a product with acceptable compressive strength, dimensional stability and elastic modulus. Storage of samples under water appears to have no detrimental effects on the product's properties. (author)

  18. Gut microbiota of the pine weevil degrades conifer diterpenes and increases insect fitness.

    Science.gov (United States)

    Berasategui, Aileen; Salem, Hassan; Paetz, Christian; Santoro, Maricel; Gershenzon, Jonathan; Kaltenpoth, Martin; Schmidt, Axel

    2017-08-01

    The pine weevil (Hylobius abietis), a major pest of conifer forests throughout Europe, feeds on the bark and cambium, tissues rich in terpenoid resins that are toxic to many insect herbivores. Here, we report the ability of the pine weevil gut microbiota to degrade the diterpene acids of Norway spruce. The diterpene acid levels present in ingested bark were substantially reduced on passage through the pine weevil gut. This reduction was significantly less upon antibiotic treatment, and supplementing the diet with gut suspensions from untreated insects restored the ability to degrade diterpenes. In addition, cultured bacteria isolated from pine weevil guts were shown to degrade a Norway spruce diterpene acid. In a metagenomic survey of the insect's bacterial community, we were able to annotate several genes of a previously described diterpene degradation (dit) gene cluster. Antibiotic treatment disrupted the core bacterial community of H. abietis guts and eliminated nearly all dit genes concordant with its reduction in diterpene degradation. Pine weevils reared on an artificial diet spiked with diterpenes, but without antibiotics, were found to lay more eggs with a higher hatching rate than weevils raised on diets with antibiotics or without diterpenes. These results suggest that gut symbionts contribute towards host fitness, but not by detoxification of diterpenes, as these compounds do not show toxic effects with or without antibiotics. Rather the ability to thrive in a terpene-rich environment appears to allow gut microbes to benefit the weevil in other ways, such as increasing the nutritional properties of their diet. © 2017 John Wiley & Sons Ltd.

  19. Cobalt Ions Improve the Strength of Epoxy Resins

    Science.gov (United States)

    Stoakley, D. M.; St. Clair, A. K.

    1986-01-01

    Technique developed for improving mechanical strength of epoxy resins by adding cobalt ions in form of tris(acetylacetonato)cobalt (III) complex. Solid cast disks prepared from cobalt ion-containing epoxy resins tested for flexural strength and stiffness. Incorporation of cobalt ions into epoxies increased flexural strength of resins by 10 to 95 percent. Suitable resins for this technique include any liquid or solid TGMDA resins. Improved epoxy formulation proves useful as composite matrix resin, adhesive, or casting resin for applications on commercial and advanced aircraft.

  20. Shear bond strength of the amalgam-resin composite interface.

    Science.gov (United States)

    Machado, Camilo; Sanchez, Eliana; Alapati, Satish; Seghi, Robert; Johnston, William

    2007-01-01

    This study compared the initial and one year shear bond strengths (SBS) of resin composite bonded to amalgam using Amalgambond-Plus. Resin composite cylinders (Point 4, Kerr Corporation) were bonded to either etched-enamel (A), 50% etched enamel-50% polished amalgam (B), airborne-particle abraded amalgam (C), carbide bur prepared amalgam (D) and airborne-particle abraded 50% amalgam-50% etched-enamel (E). Shear bond strengths were determined using a standardized testing device (Ultradent Products) in a universal testing machine (Instron model 4204). The failed interfaces were evaluated with SEM to obtain visual evidence of the failure mode. ANOVA indicated significant differences among the groups (p composite masking has the strongest, most durable SBS on airborne-particle abraded amalgam and airborne-particle abraded enamel-amalgam surfaces and could be used as a method to improve the esthetics of amalgam restorations.

  1. Does the light source affect the repairability of composite resins?

    Science.gov (United States)

    Karaman, Emel; Gönülol, Nihan

    2014-01-01

    The aim of this study was to examine the effect of the light source on the microshear bond strength of different composite resins repaired with the same substrate. Thirty cylindrical specimens of each composite resin--Filtek Silorane, Filtek Z550 (3M ESPE), Gradia Direct Anterior (GC), and Aelite Posterior (BISCO)--were prepared and light-cured with a QTH light curing unit (LCU). The specimens were aged by thermal cycling and divided into three subgroups according to the light source used--QTH, LED, or PAC (n = 10). They were repaired with the same substrate and a Clearfil Repair Kit (Kuraray). The specimens were light-cured and aged for 1 week in distilled water at 37 °C. The microshear bond strength and failure modes were assessed. There was no significant difference in the microshear bond strength values among the composite resins, except for the Filtek Silorane group that showed significantly lower bond strength values when polymerized with the PAC unit compared to the QTH or LED unit. In conclusion, previously placed dimethacrylate-based composites can be repaired with different light sources; however, if the composite to be repaired is silorane-based, then using a QTH or LED device may be the best option.

  2. Electron Beam Cured Epoxy Resin Composites for High Temperature Applications

    Science.gov (United States)

    Janke, Christopher J.; Dorsey, George F.; Havens, Stephen J.; Lopata, Vincent J.; Meador, Michael A.

    1997-01-01

    Electron beam curing of Polymer Matrix Composites (PMC's) is a nonthermal, nonautoclave curing process that has been demonstrated to be a cost effective and advantageous alternative to conventional thermal curing. Advantages of electron beam curing include: reduced manufacturing costs; significantly reduced curing times; improvements in part quality and performance; reduced environmental and health concerns; and improvement in material handling. In 1994 a Cooperative Research and Development Agreement (CRADA), sponsored by the Department of Energy Defense Programs and 10 industrial partners, was established to advance the electron beam curing of PMC technology. Over the last several years a significant amount of effort within the CRADA has been devoted to the development and optimization of resin systems and PMCs that match the performance of thermal cured composites. This highly successful materials development effort has resulted in a board family of high performance, electron beam curable cationic epoxy resin systems possessing a wide range of excellent processing and property profiles. Hundreds of resin systems, both toughened and untoughened, offering unlimited formulation and processing flexibility have been developed and evaluated in the CRADA program.

  3. Contact allergy to reactive diluents and related aliphatic epoxy resins.

    Science.gov (United States)

    Aalto-Korte, Kristiina; Kuuliala, Outi; Henriks-Eckerman, Maj-Len; Suuronen, Katri

    2015-06-01

    Diglycidyl ether of bisphenol A resin (DGEBA-R) is the most common sensitizer in epoxy systems, but a minority of patients also develop contact allergy to reactive diluents. To analyse the frequency and clinical relevance of allergic reactions to different epoxy reactive diluents and related aliphatic epoxy resins. Test files (January 1991 to June 2014) were screened, and the clinical records of patients with allergic reactions were analysed for occupation, concomitant allergic reactions, and exposure. A total of 67 patients reacted to at least one of the compounds. The largest numbers of allergic reactions were to phenyl glycidyl ether (PGE; n = 41), 1,4-butanediol diglycidyl ether (BDDGE; n = 34), and p-tert-butylphenyl glycidyl ether (PTBPGE; n = 19). Ten of the patients did not have contact allergy to DGEBA-R. The reactions of 5 of these were related to the use of BDDGE-containing products. We found no significant exposure to PGE or PTBPGE in patients sensitized to them, but some of the patients had used cresyl glycidyl ether-containing products. Allergic reactions to reactive diluents and related aliphatic epoxy resins usually occurred together with reactions to DGEBA-R. BDDGE was the clinically most significant compound, and was the sole cause of occupational allergic contact dermatitis in 3 patients. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Shear bond strength of an autopolymerizing repair resin to injection-molded thermoplastic denture base resins.

    Science.gov (United States)

    Hamanaka, Ippei; Shimizu, Hiroshi; Takahashi, Yutaka

    2013-09-01

    This study investigated the shear bond strength of an autopolymerizing repair resin to injection-molded thermoplastic denture base resins. Four injection-molded thermoplastic resins (two polyamides, a polyethylene terephthalate copolymer and a polycarbonate) were used in this study. The specimens were divided into eight groups according to the type of surface treatment given: (1) no treatment, (2) air abrasion with alumina, (3) dichloromethane, (4) ethyl acetate, (5) 4-META/MMA-TBB resin, (6) alumina and 4-META/MMA-TBB resin, (7) tribochemical silica coating or (8) tribochemical silica coating and 4-META/MMA-TBB resin. Half of the specimens in groups 1, 5, 6 and 8 were thermocycled for 10,000 cycles in water between 5-55°C with a dwell time of 1 min at each temperature. The shear bond strengths were determined. The shear bond strengths to the two polyamides treated with alumina, dichloromethane and ethyl acetate and no treatment were very low. The greatest post-thermocycling bond strengths to polyamides were recorded for the specimens treated with tribochemical silica coating and 4-META/MMA-TBB resin (PA12: 16.4 MPa, PACM12: 17.5 MPa). The greatest post-thermocycling bond strengths to polyethylene terephthalate copolymer and polycarbonate were recorded for the treatment with alumina and 4-META/MMA-TBB resin (22.7 MPa, 20.8 MPa). Polyamide was exceedingly difficult to bond to an autopolymerizing repair resin; the shear bond strength improved using tribochemical silica coating followed by the application of 4-META/MMA-TBB resin. Both polyethylene terephthalate copolymer and polycarbonate were originally easy to bond to an autopolymerizing repair resin. However, with 4-META/MMA-TBB resin, the bond was more secure.

  5. Magnetic ion-exchange resin treatment: Impact of water type and resin use

    OpenAIRE

    Mergen, Maxime Rodolphe Denis; Jefferson, Bruce; Parsons, Simon A.; Jarvis, Peter

    2008-01-01

    Three raw waters of fundamentally different natural organic matter (NOM) character were treated by magnetic resin using a bench-scale method designed to mimic how the resin is used in continuous operation. Increasing water hydrophobicity resulted in reduced dissolved organic carbon (DOC) removal with removal of 56%, 33% and 25% for waters containing 21%, 50% and 75% hydrophobic NOM, respectively. Study of consecutive resin uses showed that the NOM in the hydrophobic water ha...

  6. 5-year clinical performance of resin composite versus resin modified glass ionomer restorative system in non-carious cervical lesions

    DEFF Research Database (Denmark)

    Franco, Eduardo Batista; Benetti, Ana Raquel; Ishikiriama, Sérgio Kiyoshi

    2006-01-01

    To comparatively assess the 5-year clinical performance of a 1-bottle adhesive and resin composite system with a resin-modified glass ionomer restorative in non-carious cervical lesions.......To comparatively assess the 5-year clinical performance of a 1-bottle adhesive and resin composite system with a resin-modified glass ionomer restorative in non-carious cervical lesions....

  7. 21 CFR 175.380 - Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins.

    Science.gov (United States)

    2010-04-01

    ...-isopropylidenediphenol-epichlorohydrin epoxy resins. 175.380 Section 175.380 Food and Drugs FOOD AND DRUG ADMINISTRATION... Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins. The...′-isopropylidenediphenol-epichlorohydrin epoxy resins, to which may have been added certain optional adjuvant substances...

  8. Comparative analysis of the shrinkage stress of composite resins

    Directory of Open Access Journals (Sweden)

    Rosana Aparecida Pereira

    2008-02-01

    Full Text Available The aim of this study was to compare the shrinkage stress of composite resins by three methods. In the first method, composites were inserted between two stainless steel plates. One of the plates was connected to a 20 kgf load cell of a universal testing machine (EMIC-DL-500. In the second method, disk-shaped cavities were prepared in 2-mm-thick Teflon molds and filled with the different composites. Gaps between the composites and molds formed after polymerization were evaluated microscopically. In the third method, the wall-to-wall shrinkage stress of the resins that were placed in bovine dentin cavities was evaluated. The gaps were measured microscopically. Data were analyzed by one-way ANOVA and Tukey's test (alpha=0.05. The obtained contraction forces were: Grandio = 12.18 ± 0.428N; Filtek Z 250 = 11.80 ± 0.760N; Filtek Supreme = 11.80 ± 0.707 N; and Admira = 11.89 ± 0.647 N. The gaps obtained between composites and Teflon molds were: Filtek Z 250 = 0.51 ± 0.0357%; Filtek Supreme = 0.36 ± 0.0438%; Admira = 0.25 ± 0.0346% and Grandio = 0.16 ± 0.008%. The gaps obtained in wall-to-wall contraction were: Filtek Z 250 = 11.33 ± 2.160 µm; Filtek Supreme = 10.66 ± 1.211µm; Admira = 11.16 ± 2.041 µm and Grandio = 10.50 ± 1.224 µm. There were no significant differences among the composite resins obtained with the first (shrinkage stress generated during polymerization and third method (wall-to-wall shrinkage. The composite resins obtained with the second method (Teflon method differed significantly regarding gap formation.

  9. Resin composites: Modulus of elasticity and marginal quality.

    Science.gov (United States)

    Benetti, Ana R; Peutzfeldt, Anne; Lussi, Adrian; Flury, Simon

    2014-09-01

    To investigate how the modulus of elasticity of resin composites influences marginal quality in restorations submitted to thermocyclic and mechanical loading. Charisma, Filtek Supreme XTE and Grandio were selected as they were found to possess different moduli of elasticity but quite similar polymerization contraction. MOD cavities (n=30) were prepared in extracted premolars, restored and then subjected to thermocyclic and mechanical loading. Marginal quality of the restorations before and after loading was analyzed on epoxy replicas under a scanning electron microscope. The percentage of gap-free margins and occurrence of paramarginal fractures were registered. Modulus of elasticity and polymerization contraction were analyzed with parametric and margins with nonparametric ANOVA and post hoc Tukey HSD or Wilcoxon rank-sum tests, respectively. The number of paramarginal fractures was analyzed with exact Fisher tests (α=0.05). Grandio demonstrated significantly more gap-free enamel margins than Charisma and Filtek Supreme XTE, before and after loading (p0.05). No significant effect of resin composite (p=0.81) on the quality of dentine margins was observed, before or after loading. Deterioration of all margins was evident after loading (pGrandio when compared to Charisma (p=0.008). The resin composite with the highest modulus of elasticity resulted in the highest number of gap-free enamel margins but with an increased incidence of paramarginal enamel fractures. The results from this study suggest that the marginal quality of restorations can be improved by the selection of a resin composite with modulus of elasticity close to that of dentine, although an increase in paramarginal enamel fractures can result as a consequence. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Comparative analysis of the shrinkage stress of composite resins.

    Science.gov (United States)

    Pereira, Rosana Aparecida; Araujo, Paulo Amarante de; Castañeda-Espinosa, Juan Carlos; Mondelli, Rafael Francisco Lia

    2008-01-01

    The aim of this study was to compare the shrinkage stress of composite resins by three methods. In the first method, composites were inserted between two stainless steel plates. One of the plates was connected to a 20 kgf load cell of a universal testing machine (EMIC-DL-500). In the second method, disk-shaped cavities were prepared in 2-mm-thick Teflon molds and filled with the different composites. Gaps between the composites and molds formed after polymerization were evaluated microscopically. In the third method, the wall-to-wall shrinkage stress of the resins that were placed in bovine dentin cavities was evaluated. The gaps were measured microscopically. Data were analyzed by one-way ANOVA and Tukey's test (alpha=0.05). The obtained contraction forces were: Grandio = 12.18 +/- 0.428N; Filtek Z 250 = 11.80 +/- 0.760N; Filtek Supreme = 11.80 +/- 0.707 N; and Admira = 11.89 +/- 0.647 N. The gaps obtained between composites and Teflon molds were: Filtek Z 250 = 0.51 +/- 0.0357%; Filtek Supreme = 0.36 +/- 0.0438%; Admira = 0.25 +/- 0.0346% and Grandio = 0.16 +/- 0.008%. The gaps obtained in wall-to-wall contraction were: Filtek Z 250 = 11.33 +/- 2.160 microm; Filtek Supreme = 10.66 +/- 1.211 microm; Admira = 11.16 +/- 2.041 microm and Grandio = 10.50 +/- 1.224 microm. There were no significant differences among the composite resins obtained with the first (shrinkage stress generated during polymerization) and third method (wall-to-wall shrinkage). The composite resins obtained with the second method (Teflon method) differed significantly regarding gap formation.

  11. Restored viability and function of dental pulp cells on poly-methylmethacrylate (PMMA)-based dental resin supplemented with N-acetyl cysteine (NAC).

    Science.gov (United States)

    Kojima, N; Yamada, M; Paranjpe, A; Tsukimura, N; Kubo, K; Jewett, A; Ogawa, T

    2008-12-01

    This study examines cytotoxicity of poly-methylmethacrylate (PMMA)-based dental temporary filling resin to dental pulp cells, and the potential amelioration of the toxicity with an anti-oxidant amino-acid, N-acetyl cysteine (NAC). Dental pulp cells extracted from rat maxillary incisors were cultured on the resin material with or without NAC incorporation, or on the polystyrene. The cultures were supplied with osteoblastic media, containing dexamethasone. Forty five percent of cells on the PMMA dental resin were necrotic at 24h after seeding. However, this percentage was reduced to 27% by incorporating NAC in the resin, which was the level equivalent to that in the culture on polystyrene. The culture on the untreated resin was found to be negative for alkaline phosphate (ALP) activity at days 5 and 10 or von Kossa mineralized nodule formation at day 20. In contrast, some areas of the cultures on NAC-incorporated resin substrates were ALP and von Kossa positive. Collagen I and dentin sialoprotein genes were barely expressed in day 7 culture on the untreated resin. However, those genes were expressed in the culture on the resin with NAC. These results suggest that the decreased cell viability and the nearly completely suppressed odontoblast-like cell phenotype of dental pulp cells cultured on PMMA dental resin can be salvaged to a biologically significant degree by the incorporation of NAC in the resin.

  12. Bonding effectiveness of self-adhesive and conventional-type adhesive resin cements to CAD/CAM resin blocks. Part 1: Effects of sandblasting and silanization.

    Science.gov (United States)

    Higashi, Mami; Matsumoto, Mariko; Kawaguchi, Asuka; Miura, Jiro; Minamino, Takuya; Kabetani, Tomoshige; Takeshige, Fumio; Mine, Atsushi; Yatani, Hirofumi

    2016-01-01

    The present study assessed the effect of sandblasting and silanization on resin cement bond strengths to CAD/CAM resin blocks. Twenty four blocks (KATANA AVENCIA BLOCK) were divided into two resin cement groups (PANAVIA V5 [PV5] and PANAVIA SA CEMENT HANDMIX [PSA]), and further divided into four subgroups representing different surface treatment methods: no treatment (Ctl), silanization (Si), sandblasting (Sb), and Sb+Si. After resin application, microtensile bond strengths (μTBSs) were measured immediately, 1, 3 and 6 months after water storage. In addition, surfaces resulting from each of the treatment methods were analyzed by scanning electron microscopy (SEM). Three-way analysis of variance revealed a statistically significant effect for the parameters 'surface treatment' (p<0.001, F=370), 'resin cement' (p<0.001, F=103, PSAsignificantly lower μTBS values compared to other treatment subgroups (p<0.001). The highest bond strength was achieved with Sb+Si treatment. SEM revealed that sandblasting roughened surfaces.

  13. The strengthening of resin cemented dental ceramic materials

    OpenAIRE

    Hooi, Paul

    2013-01-01

    The aim of the current investigation was to advance the understanding of the mechanism of resin-strengthening conferred to dental ceramic materials by resin-based composite materials. The investigation is presented as a series of manuscripts. In the first study (Manuscript 3.1), dental porcelain disc-shaped specimens were resin-coated with three resin-based composite materials with different flexural moduli at discrete resin thicknesses. The discs were loaded to failure in a biaxial flexure t...

  14. Pengaruh Sifat-Sifat Fisik Resin Akrilik Terhadap Basis Protesa

    OpenAIRE

    Amriani Syahfitri

    2008-01-01

    Saat ini resin akrilik banyak digunakan secara umum untuk konstruksi gigi tiruan. Sebagai bahan basis prothesa, penggunaan resin akrilik terutama resin heat cured adalah yang paling sering digunakan selain bernilai estetis, juga lebih ekonomis. Pada prothesa yang ideal memerlukan suatu basis yang kuat, Syarat- syarat basis protesa tidak semuanya dapat dipenuhi oleh basis resin akrilik. Sifat-sifat fisik resin akrilik mempunyai pengaruh terhadap basis protesa. Untuk menghindari k...

  15. STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS

    International Nuclear Information System (INIS)

    Braverman, J.I.; Miller, C.A.; Ellingwood, B.R.; Naus, D.J.; Hofmayer, C.H.; Bezler, P.; Chang, T.Y.

    2001-01-01

    This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits

  16. Effect of LED and Argon Laser on Degree of Conversion and Temperature Rise of Hybrid and Low Shrinkage Composite Resins.

    Science.gov (United States)

    Pahlevan, Ayob; Tabatabaei, Masumeh Hasani; Arami, Sakineh; Valizadeh, Sara

    2016-01-01

    Different light curing units are used for polymerization of composite resins. The aim of this study was to evaluate the degree of conversion (DC) and temperature rise in hybrid and low shrinkage composite resins cured by LED and Argon Laser curing lights. DC was measured using FTIR spectroscopy. For measuring temperature rise, composite resin samples were placed in Teflon molds and cured from the top. The thermocouple under samples recorded the temperature rise. After initial radiation and specimens reaching the ambient temperature, reirradiation was done and temperature was recorded again. Both temperature rise and DC data submitted to one-way ANOVA and Tukey-HSD tests (5% significance). The obtained results revealed that DC was not significantly different between the understudy composite resins or curing units. Low shrinkage composite resin showed a significantly higher temperature rise than hybrid composite resin. Argon laser caused the lowest temperature rise among the curing units. Energy density of light curing units was correlated with the DC. Type of composite resin and light curing unit had a significant effect on temperature rise due to polymerization and curing unit, respectively.

  17. Resin Flow Analysis in the Injection Cycle of a Resin Transfer Molded Radome

    Science.gov (United States)

    Golestanian, Hossein; Poursina, Mehrdad

    2007-04-01

    Resin flow analysis in the injection cycle of an RTM process was investigated. Fiberglass and carbon fiber mats were used as reinforcements with EPON 826 epoxy resin. Numerical models were developed in ANSYS finite element software to simulate resin flow behavior into a mold of conical shape. Resin flow into the woven fiber mats is modeled as flow through porous media. The injection time for fiberglass/epoxy composite is found to be 4407 seconds. Required injection time for the carbon/epoxy composite is 27022 seconds. Higher injection time for carbon/epoxy part is due to lower permeability value of the carbon fibers compared to glass fiber mat.

  18. Dental repair material: a resin-modified glass-ionomer bioactive ionic resin-based composite.

    Science.gov (United States)

    Croll, Theodore P; Berg, Joel H; Donly, Kevin J

    2015-01-01

    This report documents treatment and repair of three carious teeth that were restored with a new dental repair material that features the characteristics of both resin-modified glass-ionomer restorative cement (RMGI) and resin-based composite (RBC). The restorative products presented are reported by the manufacturer to be the first bioactive dental materials with an ionic resin matrix, a shock-absorbing resin component, and bioactive fillers that mimic the physical and chemical properties of natural teeth. The restorative material and base/liner, which feature three hardening mechanisms, could prove to be a notable advancement in the adhesive dentistry restorative materials continuum.

  19. Degradation behavior of carbon nanotubes/phenol-furfuryl alcohol multifunctional composites with aerospace application

    Science.gov (United States)

    Conejo, L. S.; Costa, M. L.; Oishi, S. S.; Botelho, E. C.

    2017-10-01

    Lightweight and highly conductive composite associated with good impact and tribological properties could be used in the aerospace industry to replace metal for an aircraft skin and still provide effective shielding against electromagnetic interference (EMI). Also, phenol-furfuryl alcohol resins (PFA) are excellent candidates to replace existing thermoset matrices used for obtaining glassy carbon, both in its pure form and reinforced with nanoscale structures. The synthesis of PFA allow obtaining a resin with better properties than that showed by conventional phenolic resins and with synthesis and cure processes more controlled than observed for the furfuryl alcohol resin. This work has as main purpose the synthesis and thermal characterization of PFA resin and its nanostructured composites with different concentrations of carbon nanotubes (0, 0.1, 0.5 and 1.0 wt%). PFA resin was synthesized with 1:2:1 molar ratio of phenol/formaldehyde/furfuryl alcohol, according to the more appropriate condition obtained previously. The specimens were evaluated by thermogravimetry (TGA) to knowledge of the temperature of thermal degradation, either by actual analyses as simulated by simulation heating rate conversion software (known as Highway Simulation). The introduction of CNT in PFA sample does not affect its thermal stability. The values of residual weight found for samples with CNT additions are close to the values of the phenolic resin in the literature (about 60% residual weight).

  20. Ion Exchange Testing with SRF Resin FY 2012

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Renee L.; Rinehart, Donald E.; Peterson, Reid A.

    2014-07-02

    Ion exchange using spherical resorcinol-formaldehyde (SRF) resin has been selected by the U.S. Department of Energy’s Office of River Protection (DOE-ORP) for use in the Pretreatment Facility (PTF) of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) and for potential application in at-tank deployment. Numerous studies have shown SRF resin to be effective for removing 137Cs from a wide variety of actual and simulated tank waste supernatants (Adamson et al. 2006; Blanchard et al. 2008; Burgeson et al. 2004; Duignan and Nash 2009; Fiskum et al. 2006a; Fiskum et al. 2006b; Fiskum et al. 2006c; Fiskum et al. 2007; Hassan and Adu-Wusu 2003; King et al. 2004; Nash et al. 2006). Prior work at the Pacific Northwest National Laboratory (PNNL) has focused primarily on the loading behavior for 4 to 6 M Na solutions at 25 to 45°C. Recent proposed changes to the WTP ion exchange process baseline indicate that loading may include a broader range of sodium molarities (0.1 to 8 M) and higher temperatures (50°C) to alleviate post-filtration precipitation issues. This report discusses ion exchange loading kinetics testing activities performed in accordance with Test Plan TP-WTPSP-002, Rev. 3.01, which was prepared and approved in response to the Test Specification 24590-PTF-TSP-RT-09-002, Rev. 0 (Lehrman 2010) and Test Exception 24590-PTF-TEF-RT-11-00003, Rev. 0 (Meehan 2011). This testing focused on column tests evaluating the impact of elevated temperature on resin degradation over an extended period of time and batch contacts evaluating the impact on Cs loading over a broad range of sodium concentrations (0.1 to 5 M). These changes may be required to alleviate post-filtration precipitation issues and broaden the data range of SRF resin loading under the conditions expected with the new equipment and process changes.

  1. Trypsin-catalyzed deltamethrin degradation.

    Directory of Open Access Journals (Sweden)

    Chunrong Xiong

    Full Text Available To explore if trypsin could catalyze the degradation of non-protein molecule deltamethrin, we compared in vitro hydrolytic reactions of deltamethrin in the presence and absence of trypsin with ultraviolet-visible (UV/Vis spectrophotometry and gas chromatography-mass spectrometry (GC/MS. In addition, acute oral toxicity of the degradation products was determined in Wistar rats. The results show that the absorption peak of deltamethrin is around 264 nm, while the absorption peaks of deltamethrin degradation products are around 250 nm and 296 nm. In our GC setting, the retention time of undegraded deltamethrin was 37.968 min, while those of deltamethrin degradation products were 15.289 min and 18.730 min. The LD50 of deltamethrin in Wistar rats is 55 mg/kg, while that of deltamethrin degradation products is 3358 mg/kg in female rats and 1045 mg/kg in male rates (61-fold and 19-fold reductions in toxicity, suggesting that trypsin could directly degrade deltamethrin, which significantly reduces the toxicity of deltamethrin. These results expand people's understanding of the functions of proteases and point to potential applications of trypsin as an attractive agent to control residual pesticides in the environment and on agricultural products.

  2. Three-year clinical evaluation of different restorative resins in class I restorations.

    Science.gov (United States)

    Yazici, A R; Ustunkol, I; Ozgunaltay, G; Dayangac, B

    2014-01-01

    The aim of the present study was to evaluate the three-year clinical performance of a nanofilled resin composite, a packable resin composite, and silorane-based resin restorations in Class I occlusal cavities. Twenty-eight patients with at least three similar-sized occlusal lesions in molar teeth participated in the study. A total of 84 Class I occlusal restorations were placed: 28 with nanofilled resin composite (Filtek Supreme), 28 with packable resin composite (P60), and 28 with silorane-based resin (Filtek Silorane). Filtek Supreme and P60 were used with their respective etch-and-rinse adhesive system, Adper Single Bond 2, and Filtek Silorane was used with its respective self-etch adhesive, Filtek Silorane Adhesive. All restorations were placed by the same operator. The restorations were evaluated at baseline, at six months, and annually for three years according to modified US Public Health Service criteria by two calibrated examiners who did not know which restorative resin had been used. The three restorative materials for each category were compared using the χ (2) test at a significance level of 0.05. Cochran's Q test was used to compare the changes across the five time points for each restorative material. McNemar's test followed by Bonferroni adjustment was used when significance differences were found. At the end of the three years, 60 restorations were evaluated in 20 patients, with a recall rate of 71.4%. The retention rate was 100% for all restorative resins. Eight restorations from the P60 group, ten from the Filtek Supreme group, and nine from the Filtek Silorane group were rated Bravo for marginal discoloration. For marginal adaptation, three P60, five Filtek Supreme, and 11 Filtek Silorane restorations were rated Bravo. No statistically significant differences in overall clinical performance were found between the restorative materials except for marginal adaptation. P60 showed the best marginal adaptation at the end of the three years. No