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Sample records for tyrosine-derived polycarbonates effects

  1. Dielectric Relaxation Behavior of Tyrosine-Derived Polycarbonate.

    Science.gov (United States)

    Suarez, N.; Laredo, E.; Bello, A.; Kohn, J.

    1996-03-01

    Tyrosine-derived polycarbonates represent a new family of polymers that were specifically designed for medical applications. In this work we have used Thermally Stimulated Depolarization Currents (TSDC) to study for the first time the dielectric relaxation behavior of a series of degradable tyrosine-derived polycarbonates. The test polymers differed only in the length of the pendent chain which was increased from two to eight carbons by the use of ethyl, butyl, hexyl and octyl esters as C-terminus protecting groups. The high temperature zone of the spectra shows the glass transition relaxation located at decreasing temperatures as the length of the pendent chain is increased. The low temperature spectrum exhibits a complex dielectric relaxation composed of 4 peaks. The relative intensities of these four peaks are sensitive to packing and entanglement effects caused by the variation in the length of the pendent chain. For data analysis, the Direct Signal Analysis (DSA) procedure was used. This procedure allows the precise determination of the relaxation parameters without having to use peak cleaning techniques. To analyze the whole spectra the Vogel-Fulcher temperature dependence of the relaxation time was used for the glass transition relaxation, and the Arrhenius dependence for the remaining relaxations.

  2. Tyrosine-derived polycarbonate scaffolds for bone regeneration in a rabbit radius critical-size defect model

    International Nuclear Information System (INIS)

    Kim, Jinku; McBride, Sean; Donovan, Amy; Hollinger, Jeffrey O; Darr, Aniq; Magno, Maria Hanshella R

    2015-01-01

    The aim of the study was to determine bone regeneration in a rabbit radius critical-size defect (CSD) model using a specific polymer composition (E1001(1k)) from a library of tyrosine-derived polycarbonate scaffolds coated with a calcium phosphate (CP) formulation (E1001(1k) + CP) supplemented with recombinant human bone morphogenetic protein-2 (rhBMP-2). Specific doses of rhBMP-2 (0, 17, and 35 μg/scaffold) were used. E1001(1k) + CP scaffolds were implanted in unilateral segmental defects (15 mm length) in the radial diaphyses of New Zealand White rabbits. At 4 and 8 weeks post-implantation, bone regeneration was determined using micro-computed tomography (µCT), histology, and histomorphometry. The quantitative outcome data suggest that E1001(1k) + CP scaffolds with rhBMP-2 were biocompatible and promoted bone regeneration in segmental bone defects. Histological examination of the implant sites showed that scaffolds made of E1001(1k) + CP did not elicit adverse cellular or tissue responses throughout test periods up to 8 weeks. Noteworthy is that the incorporation of a very small amount of rhBMP-2 into the scaffolds (as low as 17 μg/defect site) promoted significant bone regeneration compared to scaffolds consisting of E1001(1k) + CP alone. This finding indicates that E1001(1k) + CP may be an effective platform for bone regeneration in a critical size rabbit radius segmental defect model, requiring only a minimal dose of rhBMP-2. (paper)

  3. Angiogenic competency of biodegradable hydrogels fabricated from polyethylene glycol-crosslinked tyrosine-derived polycarbonates

    Directory of Open Access Journals (Sweden)

    HJ Sung

    2008-04-01

    Full Text Available Synthetic biomaterials can be used as instructive biological milieus to guide cellular behaviour and function. To further realize this application, we synthesized a series of structurally similar hydrogels and tested their ability to modulate angiogenesis. Hydrogels were synthesized from poly(DTE-co-x% DT carbonate crosslinked by y% poly(ethylene glycol (PEG. Hydrogel desaminotyrosyl tyrosine (DT contents (x% ranged from 10-100%, and crosslink densities (y% PEG-crosslinker ranged from 5-80%. The hydrogels were fashioned into porous scaffolds with highly interconnected macro- and micro-pore (>100 and <10 mm in diameter, respectively architecture using poly(DTE-co-10%DT carbonate crosslinked with 8% PEG. Under physiological conditions (in vitro, the hydrogels degraded into three major products: desaminotyrosyl-tyrosine ethyl ester (DTE, desaminotyrosyl tyrosine (DT, and poly(ethylene glycol-di-DT-hydrazide (PEG-di-DT hydrazide. Increasing either DT content or crosslink density brought quickened degradation. Because DT and DTE, two of the three major degradation products, have not demonstrated any noticeable cytotoxicity or angiogenic effect in previous studies, we measured the cytotoxicity of PEG-di-DT hydrazide, the third major degradation product. We found that PEG-di-DT hydrazide only displayed significant cytotoxicity at the high concentration of 100 mg/mL. Interestingly, PEG-di-DT hydrazide and its further degradation product PEG-dihydrazide stimulated in vitro endothelial cell migration and tubulogenesis, which is comparable to results found with FGF-beta treatment. Subcutaneous implantation of the PEG-crosslinked poly(DTE-co-10%DT carbonate scaffolds into the backs of rats elicited greater tissue growth over time and superior vascularization than poly(DTE carbonate implantation. These results show that this new class of biomaterials has a strong potential to modulate angiogenesis.

  4. Impact of Polymer-bound Iodine on Fibronectin Adsorption and Osteoblast Cell Morphology Radiopaque Medical Polymers: Tyrosine-derived Polycarbonate Blends as a Model System

    Science.gov (United States)

    Aamer, Khaled A.; Genson, Kirsten L.; Kohn, Joachim; Becker, Matthew L.

    2012-01-01

    Imaging of polymer implants during surgical implantations is challenging in that most materials lack sufficient X-ray contrast. Synthetic derivatization with iodine serves to increase the scattering contrast but results in distinct physico-chemical properties in the material which influence subsequent protein adsorption and cell morphology behavior. Herein we report the impact of increasing iodine inclusion on the cell morphology (cell area and shape) of MC3T3-E1 osteoblasts on a series of homopolymers and discrete blend thin films of poly(desaminotyrosyl tyrosine ethyl ester carbonate), poly(DTE carbonate) and an iodinated analogue poly(I2-DTE carbonate). Cell morphology is correlated to film chemical composition via measuring Fibronectin (FN) adhesion protein adsorption profile on these films. FN exhibits up to 2 fold greater adsorption affinity for poly(I2-DTE carbonate) than (poly(DTE carbonate)). A correlation was established between cell area, roundness and the measured FN adsorption profile on the blend films up to 75 % by mass poly(I2-DTE carbonate). Data suggest that incorporation of iodine within the polymer backbone has a distinct impact on the way FN proteins adsorb to the surface and within the studied blend systems; the effect is composition dependent. PMID:19645443

  5. Photoplastic effect in polycarbonate using microhardness ...

    Indian Academy of Sciences (India)

    ... has been employed to detect the photoplastic effect in the transparent polycarbonate specimens in darkness and under mercury illumination. For low applied loads, the hardening of specimens under illumination confirms the positive photoplastic effect that causes illumination-induced increase of crosslinking (in polymer).

  6. Gamma radiation effect study in polycarbonate optical and mechanics properties

    International Nuclear Information System (INIS)

    Araujo, E.S. de.

    1991-02-01

    Polycarbonates (PC) are used in different industrial applications due to their excellent dielectric characteristics, impact resistance, and high temperature resistance. In some of these applications, the polycarbonates are exposed to gamma radiation which produces molecular scissions, causing changes in the polycarbonate properties. To estimate the radiation effects in the Durolon polycarbonate, samples were irradiated with 60 Co gamma rays with doses between 0,2 kGy and 300 kGy. The results obtained showed that the PC mechanical properties are not changed due to the gamma radiation. However the results showed an expressive variation in the yellowness index for doses above 1 kGy. The results showed that it is possible to use the gamma sterilization of PC in applications where the coloration of PC is not critical. (author). 21 refs, 25 figs, 3 tabs

  7. Photoplastic effect in polycarbonate using microhardness ...

    Indian Academy of Sciences (India)

    Unknown

    (Lopez 1993). Microhardness seems to be especially suited in monitoring the surface phenomenon of radiation induced effect on polymers because it investigates the sur- face of the materials and is a non-destructive technique for studying the various physical properties of polymers. (Gonzalez et al 1986). 2. Experimental.

  8. Effect of metal chlorides on thermal degradation of (waste) polycarbonate.

    Science.gov (United States)

    Chiu, Shwu-Jer; Chen, Shi-Hau; Tsai, Chou-Tso

    2006-01-01

    In this study, we investigated how to treat (waste) polycarbonate efficiently to reduce its degraded residue. The study was carried out in an isothermal reactor under continuous nitrogen flow at atmospheric pressure to pyrolyze polycarbonate (PC) alone and in the presence of metal chloride. Some metal chlorides were shown to be catalytic active for the degradation of PC at 400 degrees C, which increased degradation conversion from 8.5% to more than 58.3%. Among those active metal chlorides, ZnCl2 and SnCl2 can produce higher liquid product yields. Effects such as particle size of PC, temperature, the weight ratio of metal chloride/PC, and degradation time on the degradation conversion of PC without and with these two most active metal chlorides were studied. Results of the liquid product analysis by GC/MS demonstrated the product composition of PC degradation over the metal chlorides is much simpler than that of degradation alone. The main liquid product is phenol, p-isopropylphenol, diphenyl carbonate, and bisphenol A for all cases.

  9. Cytotoxic effects of polycarbonate-based orthodontic brackets by activation of mitochondrial apoptotic mechanisms

    NARCIS (Netherlands)

    Kloukos, D.; Taoufik, E.; Eliades, T.; Katsaros, C.; Eliades, G.

    2013-01-01

    OBJECTIVES: The aim of the study was to evaluate the biological effects of water eluents from polycarbonate based esthetic orthodontic brackets. METHODS: The composite polycarbonate brackets tested were Silkon Plus (SL, fiber-glass-reinforced), Elan ME (EL, ceramic particle-reinforced) and Elegance

  10. Strain rate effects in polycarbonate/ABS blends

    NARCIS (Netherlands)

    Inberg, J.P.F.; Takens, A.; Gaymans, R.J.

    2002-01-01

    Acrylonitrile–butadiene–styrene was blended in polycarbonate using a twin-screw extruder, producing dispersed and co-continuous blends. The blends were injection moulded into test bars. These materials were tested in single edge notch tensile tests as a function of test speed over a test speed range

  11. Bonding polycarbonate brackets to ceramic: : Effects of substrate treatment on bond strength

    NARCIS (Netherlands)

    Özcan, Mutlu; Vallittu, Pekka K.; Peltomäki, Timo; Huysmans, Marie-Charlotte; Kalk, Warner

    2004-01-01

    This study evaluated the effects of 5 different surface conditioning methods on the bond strength of polycarbonate brackets bonded to ceramic surfaces with resin based cement. Six disc-shaped ceramic specimens (feldspathic porcelain) with glazed surfaces were used for each group. The specimens were

  12. Tyrosine-derived polycarbonate-silica xerogel nanocomposites for controlled drug delivery.

    Science.gov (United States)

    Costache, M C; Vaughan, A D; Qu, H; Ducheyne, P; Devore, D I

    2013-05-01

    Biodegradable polymer-ceramic composites offer significant potential advantages in biomedical applications where the properties of either polymers or ceramics alone are insufficient to meet performance requirements. Here we demonstrate the highly tunable mechanical and controlled drug delivery properties accessible with novel biodegradable nanocomposites prepared by non-covalent binding of silica xerogels and co-polymers of tyrosine-poly(ethylene glycol)-derived poly(ether carbonate). The Young's moduli of the nanocomposites exceed by factors of 5-20 times those of the co-polymers or of composites made with micron scale silica particles. Increasing the fraction of xerogel in the nanocomposites increases the glass transition temperature and the mechanical strength, but decreases the equilibrium water content, which are all indicative of strong non-covalent interfacial interactions between the co-polymers and the silica nanoparticles. Sustained, tunable controlled release of both hydrophilic and hydrophobic therapeutic agents from the nanocomposites is demonstrated with two clinically significant drugs, rifampicin and bupivacaine. Bupivacaine exhibits an initial small burst release followed by slow release over the 7 day test period. Rifampicin release fits the diffusion-controlled Higuchi model and the amount released exceeds the dosage required for treatment of clinically challenging infections. These nanocomposites are thus attractive biomaterials for applications such as wound dressings, tissue engineering substrates and stents. Published by Elsevier Ltd.

  13. Tyrosine-derived Polycarbonate-silica Xerogel Nanocomposites for Controlled Drug Delivery

    Science.gov (United States)

    2013-02-05

    casting and polymer sponge methods. Biomaterials 2003;24:3293–302. [12] Mitragotri S, Lahann J. Physical approaches to biomaterial design. Nat Mater...1996. [43] Percival SL, Bowler PG, Dolman J. Antimicrobial activity of silver containing dressings on wound microorganisms using an in vitro biofilm

  14. Effect of alkali treatment on the morphology and tensile properties of Cordia dichotoma fabric/polycarbonate composites

    CSIR Research Space (South Africa)

    Jayaramudu, J

    2013-05-01

    Full Text Available universal testing machine. The effects of alkali treatment and the polycarbonate coating on the tensile properties of the fabric were studied. The morphology of the fabric before and after alkali treatment andpolycarbonate coating was studied using...

  15. Irradiation effects in polycarbonate induced by 2.1 GeV Kr ions

    International Nuclear Information System (INIS)

    Tian Huixian; Jin Yunfan; Zhu Zhiyong; Liu Changlong; Sun Youmei; Wang Zhiguang; Liu Jie; Chen Xiaoxi; Wang Yanbin; Hou Mingdong

    2002-01-01

    Polycarbonate films were irradiated with 2.1 GeV Kr ions at room temperature in vacuum and in atmosphere, respectively. The ion beam induced effects were studied by means of Fourier transform infrared (FTIR) and ultraviolet visible (UV/VIS) spectroscopies in reflective mode. FTIR measurements indicate that the main effects are bond breaking, chain scissions and bond rearrangement. The creation of alkyne is the result of bond breaking and bond rearrangement. UV/VIS measurements indicate that at wavelengths of 380, 450 and 500 nm, the normalized absorbances follow approximately a linear relationship with the energy deposited density

  16. The combined effect of gamma radiation and stress cracking in polycarbonate

    International Nuclear Information System (INIS)

    Melo, Raphaela N. de; Rabello, Marcelo S.

    2009-01-01

    In this work the combined effect of gamma irradiation and stress cracking was studied in polycarbonate (PC). Tensile test bars were produced by injection moulding and then exposed to different doses of gamma radiation. After that they were submitted to the contact with isopropanol, the stress cracking agent used in this work. The specimens were tested for mechanical properties, viscosity molecular weight and fractography. The results indicated that the previous radiation intensified the stress cracking effects, as evidenced by the reduction in tensile properties and surface damage caused to the samples. (author)

  17. The effects of carbon dioxide exposure on permeation behavior in silicone rubber and glassy polycarbonates

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, S.M.

    1989-01-01

    Permeation measurements are reported for both rubbery and glassy polymers in the presence of various pure (He, CH{sub 4}, CO{sub 2}, C{sub 2}H{sub 4}) and mixed gas (O{sub 2}/N{sub 2}, CO{sub 2}/CH{sub 4}, He/CO{sub 2}, CO{sub 2}/N{sub 2}) feed streams up to 1000 psia. The polymers studied were silicone rubber and glassy bisphenol-A polycarbonate, tetramethyl polycarbonate and hexafluoro polycarbonate. Large hysteresis was observed in permeation when comparing the pressurization and depressurization responses of the glassy samples in the presence of carbon dioxide above 300 psia exposure pressure. The magnitude of the hysteresis was related to the maximum CO{sub 2} conditioning pressure used. The conditioning treatment resulted in long-lived increases in the permeability of the conditioned films and appeared to be semi-permanent if the conditioning agent was not totally removed. For CO{sub 2}/CH{sub 4} mixed gas feed streams, the conditioning treatment resulted in enhancements in flux without a significant loss in permselectivity. For the silicone rubber sample, no permeability hysteresis was observed. Exchange experiments showed that it was possible to condition a glassy polymer with CO{sub 2} to increase its permeability and to maintain a state of increased permeability even if the CO{sub 2} was replaced by another gas of sufficient solubility such as methane or air. The CO{sub 2} conditioning treatment was not apparent if the CO{sub 2} was replaced by helium without any intervening exposure to vacuum. The inability of helium to detect the effects of the CO{sub 2}-induced conditioning sensed by larger penetrants is discussed and hypothetical explanations for these unexpected results are given.

  18. Evaluation of failure characteristics and bond strength after ceramic and polycarbonate bracket debonding : effect of bracket base silanization

    NARCIS (Netherlands)

    Ozcan, M.; Finnema, K.; Ybema, A.

    The objectives of this study were to evaluate the effect of silanization on the failure type and shear-peel bond strength (SBS) of ceramic and polycarbonate brackets, and to determine the type of failure when debonded with either a universal testing machine or orthodontic pliers. Silanized and

  19. Effect of electron beam irradiation on the thermal properties of polycarbonate / polyester blend

    International Nuclear Information System (INIS)

    Zarie, K.A.

    2007-01-01

    The effect of electron beam irradiation on the thermal properties of Bayfol (polycarbonate/polyester blend) solid state nuclear track detector (SSNTD) was investigated. Non-isothermal studies were carried out using thermogravimetric analysis (TGA) and differential thermogravimetric (DTG) to obtain the activation energy of thermal decomposition for Bayfol detector. The thermogravimetric analysis (TGA) indicated that the Bayfol samples were decomposed in one main break down stage. Samples of 250 μm thickness sheets were exposed to electron beam irradiations in the dose range 20-600 KGy. The variation of melting temperatures with the electron dose was determined using differential thermal analysis (DTA). The results indicated that the electron irradiation in the dose range 200-600 KGy decreases the melting temperature of the Bayfol samples and this is most suitable for applications requiring the molding of this polymer at lower temperatures

  20. Irradiation effects in polycarbonate induced by 2.1 GeV Kr ions

    International Nuclear Information System (INIS)

    Tian Huixian; Jin Yunfan; Zhu Zhiyong; Sun Youmei; Wang Zhiguang

    2003-01-01

    Polycarbonate foil stacks were irradiated with 2.1 GeV Kr ions under vacuum at room temperature. The modifications in chemical structure induced by the irradiation were studied by means of Fourier transform infrared (FTIR) and ultraviolet visible (UV/VIS) spectroscopies. FTIR measurements reveal that material degradations through bond breaking are the main effects. Alkyne end groups are produced by the irradiation. UV/VIS measurements indicate a shifting of the absorption edge from ultraviolet towards visible, and a strong increase of absorbance in the ultraviolet and visible regions. The changes in absorbance induced by the irradiation at wavelengths of 380 nm, 450 nm and 500 nm scale well with S e n (S e is electronic energy loss) where the value of n increases from 1.69 to 2.02 with increasing of the wavelength. The results are briefly discussed

  1. Effect of neutron dose on the structural properties of Makrofol polycarbonate

    Science.gov (United States)

    Nouh, S. A.; Amer, H.; Remon, S. W.

    2009-04-01

    The effect of neutron dose on the structural properties of a Makrofol polycarbonate detector has been studied. Samples of Makrofol were classified into three main groups. The first, second and third groups were irradiated with neutrons in the dose ranges of 0.01-0.08, 0.1-0.8 and 1.0-8.0 Sv, respectively. The structural modifications in the neutron irradiated samples were studied using X-ray diffraction and Fourier-transform infrared spectroscopy. In addition, the effect of neutron dose on the intrinsic viscosity of the liquid samples, as a measure of the mean molecular mass of the Makrofol polymer, was studied. An increase in the -OH groups was observed at dose ranges of 0.01-0.04 and 3.21-8.0 Sv due to the degradation of carbonate group and the -H abstraction from the polymer backbone to form hydroxyl groups. This indicates that the degradation is dominant at these dose ranges that enhance the degree of ordering in the irradiated samples. On the other hand, irradiation in the dose range 0.04-3.21 Sv was characterized by a dominant crosslinking mechanism that led to an increase of the amorphous phase and average molecular mass.

  2. Molecular Weight and Charge Density Effects of Guanidinylated Biodegradable Polycarbonates on Antimicrobial Activity and Selectivity.

    Science.gov (United States)

    Hae Cho, Chloe A; Liang, Chao; Perera, Janesha; Liu, Jie; Varnava, Kyriakos G; Sarojini, Vijayalekshmi; Cooney, Ralph P; McGillivray, Duncan J; Brimble, Margaret A; Swift, Simon; Jin, Jianyong

    2017-11-21

    Six guanidine functionalized aliphatic biodegradable polycarbonates with varying molecular weights and charge densities were synthesized via postsynthesis modification of alkyne containing polycarbonates using Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry. The concept of passive diluting group was to modify the cationic charge density of the polycarbonate without changing its hydrophilicity. Within the molecular weight range from 8000 to 30000 g mol -1 , these guanidine polycarbonates exhibited broad-spectrum biocidal activity with low toxicity to red blood cells (RBCs). The lowest molecular weight homopolymer sample (PG-8k-100) showed the best antimicrobial activity (MIC = 40 μg/mL against Escherichia coli and MIC = 20 μg/mL against Staphylococcus epidermidis) and least RBC toxicity (0.6% hemolysis at MIC). Within the three guanidine charge densities from 20% to 70%, the low to medium dilution samples (PG-8k-7030 and PG-8k-5050) had no obvious loss in antimicrobial activities compared to the nondiluted control sample PG-8k-100. However, upon further dilution, PG-8k-2080 gave the lowest antimicrobial activity.

  3. Fluorinated copper-phthalocyanine-based n-type organic field-effect transistors with a polycarbonate gate insulator

    International Nuclear Information System (INIS)

    Sethuraman, Kunjithapatham; Kumar, Palanisamy; Santhakumar, Kannappan; Ochiai, Shizuyasu; Shin, Paikkyun

    2012-01-01

    Fluorinated copper-phthalocyanine (F 16 CuPc) thin films were prepared by using a vacuum evaporation technique and were applied to n-type organic field-effect transistors (OFETs) as active channel layers combined with a spin-coated polycarbonate thin-film gate insulator. The output characteristics of the resulting n-type OFET devices with bottom-gate/bottom-contact structures were investigated to evaluate the performances such as the field effect mobility (μ FE ), the on/off current ratio (I on/off ), and the threshold voltage (V th ). A relatively high field effect mobility of 6.0 x 10 -3 cm 2 /Vs was obtained for the n-type semiconductor under atmospheric conditions with an on/off current ratio of 1 x 10 4 and a threshold voltage of 5 V. The electron mobility of the n-type semiconductor was found to depend strongly on the growth temperature of the F 16 CuPc thin films. X-ray diffraction profiles showed that the crystallinity and the orientation of the F 16 CuPc on a polycarbonate thin film were enhanced with increasing growth temperature. Atomic force microscopy studies revealed various surface morphologies of the active layer. The field effect mobility of the F 16 CuPc-OFET was closely related to the crystallinity and the orientation of the F 16 CuPc thin film.

  4. Photodegradation of bisphenol A polycarbonate under blue light radiation and its effect on optical properties

    Science.gov (United States)

    Yazdan Mehr, M.; van Driel, W. D.; Jansen, K. M. B.; Deeben, P.; Boutelje, M.; Zhang, G. Q.

    2013-01-01

    In this investigation, the degradation mechanisms of Bisphenol A Polycarbonate (BPA-PC) plates under blue light radiation are studied. The BPA-PC plates are used both in light conversion carriers in LED modules and encapsulantes in LED packages. Optical degradation of the products is mainly due to the degradation of BPA-PC encapsulants under blue light radiation. In this study, BPA-PC plates are irradiated with blue light at elevated temperature of 140 °C for a period up to 1920 h. Optical and chemical properties of the photo-aged plates were studied using UV-Vis spectrophotometer, FTIR-ATR spectrometer, integrated sphere, and Lambda 950 spectrophotometer. The results show that increasing the exposure time leads to the discoloration, loss of optical properties, decrease of light transmission, decrease in the relative radiant power value, and increase in the yellowing index (YI) of BPA-PC plates. The results also show that there are two stages in the yellowing of polycarbonate plates. The first stage is the so-called induction period in which there is no major change in the value of YI and the rate of yellowing is very slow. This stage takes until 500 h, followed by the second yellowing regime, where the yellowing is accelerated and the rate of yellowing is comparatively faster. Both photo-Fries and photo-oxidation products are identified as the mechanisms of photo-degradation, with photo-Fries predominating as ageing time increases.

  5. Effect of Immobilized Antithrombin III on the Thromboresistance of Polycarbonate Urethane.

    Science.gov (United States)

    Lukas, Karin; Stadtherr, Karin; Gessner, Andre; Wehner, Daniel; Schmid, Thomas; Wendel, Hans Peter; Schmid, Christof; Lehle, Karla

    2017-03-24

    The surface of foils and vascular grafts made from a thermoplastic polycarbonate urethanes (PCU) (Chronoflex AR) were chemically modified using gas plasma treatment, binding of hydrogels-(1) polyethylene glycol bisdiamine and carboxymethyl dextran (PEG-DEX) and (2) polyethyleneimine (PEI)-and immobilization of human antithrombin III (AT). Their biological impact was tested in vitro under static and dynamic conditions. Static test methods showed a significantly reduced adhesion of endothelial cells, platelets, and bacteria, compared to untreated PCU. Modified PCU grafts were circulated in a Chandler-Loop model for 90 min at 37 °C with human blood. Before and after circulation, parameters of the hemostatic system (coagulation, platelets, complement, and leukocyte activation) were analyzed. PEI-AT significantly inhibited the activation of both coagulation and platelets and prevented the activation of leukocytes and complement. In conclusion, both modifications significantly reduce coagulation activation, but only PEI-AT creates anti-bacterial and anti-thrombogenic functionality.

  6. Fluorinated copper-phthalocyanine-based n-type organic field-effect transistors with a polycarbonate gate insulator

    Energy Technology Data Exchange (ETDEWEB)

    Sethuraman, Kunjithapatham [Madurai Kamaraj University, Madurai (India); Kumar, Palanisamy; Santhakumar, Kannappan; Ochiai, Shizuyasu [Aichi Institute of Technology, Toyota City (Japan); Shin, Paikkyun [Inha University, Incheon (Korea, Republic of)

    2012-07-15

    Fluorinated copper-phthalocyanine (F{sub 16}CuPc) thin films were prepared by using a vacuum evaporation technique and were applied to n-type organic field-effect transistors (OFETs) as active channel layers combined with a spin-coated polycarbonate thin-film gate insulator. The output characteristics of the resulting n-type OFET devices with bottom-gate/bottom-contact structures were investigated to evaluate the performances such as the field effect mobility (μ{sub FE}), the on/off current ratio (I{sub on/off}), and the threshold voltage (V{sub th}). A relatively high field effect mobility of 6.0 x 10{sup -3} cm{sup 2}/Vs was obtained for the n-type semiconductor under atmospheric conditions with an on/off current ratio of 1 x 10{sup 4} and a threshold voltage of 5 V. The electron mobility of the n-type semiconductor was found to depend strongly on the growth temperature of the F{sub 16}CuPc thin films. X-ray diffraction profiles showed that the crystallinity and the orientation of the F{sub 16}CuPc on a polycarbonate thin film were enhanced with increasing growth temperature. Atomic force microscopy studies revealed various surface morphologies of the active layer. The field effect mobility of the F{sub 16}CuPc-OFET was closely related to the crystallinity and the orientation of the F{sub 16}CuPc thin film.

  7. Effect of chain extenders on mechanical and thermal properties of recycled poly (ethylene terephthalate) and polycarbonate blends

    Science.gov (United States)

    Srithep, Y.; Pholharn, D.; Dassakorn, A.; Morris, J.

    2017-06-01

    Poly(ethylene terephthalate) (PET) based thermoplastics are common, particularly in packaging. Due to both thermal and hydrolytic degradation, recycled PET (rPET) shows poor mechanical properties. The effect of adding 30% polycarbonate (PC) and chain extender (CE) on mechanical, thermal and morphological properties was investigated. rPET with PC and CE was melt blended in a single screw extruder, which was then tensile test specimens were formed by injection molding rPET and PC compatibility was improved via chain extending reactions which in turn improved the rPET and PC blend mechanical properties. With the addition of 30%PC the tensile modulus of rPET increased by 18% and it increased by 223% when 2%CE was added to rPET and 30%PC blends. Also, the CE reaction affected crystallization, monitored by differential scanning calorimetry: the melting enthalpy ofblends was lowered by increased CE content.

  8. A. C. conductivity and optical properties of polycarbonate under the effect of low energy Ar+ ion beam

    International Nuclear Information System (INIS)

    EI-Mallah, H.M.; Aziz, M.S.

    2007-01-01

    A. C. conductivity and optical properties have been studied on polycarbonate sheet before and after irradiation by low energy Ar + ion beam. The a. c. conductivity σ ac ω were measured over the frequency range of 1.5x10 2 - 5x10 6 Hz at different temperatures. The irradiated samples have lower conductivity than those un irradiated between the temperature range 300 - 400 K, while the irradiated samples have higher conductivity than unirradiated sample at the temperature more than 400 K. The optical constants (the refractive index n, the absorption index k and the absorption coefficient (J. ) of unirradiated and irradiated polycarbonate sheets were calculated. The values of k and n were found to be dependent on the exposure time of the low energy Ar + ion beam. The refractive index n has anomalous behavior over the onset and the fundamental transition region. In the onset transition region, the allowed optical transition was found to be direct transition, with an optical energy gap of 0.716 eV for unirradiated sample and 0.711 and 0.706 eV for 2 and 4 minutes exposure time t e xp. respectively. In the fundamental transition region, there are two suggested transition, the first one was found to be the allowed direct transition with an optical energy gap of 2.753 eV for unirradiated sample and 2.470 and 1.897 eV for 2 and 4 minutes exposure time t e xp respectively. The other one was found to be allowed direct or indirect transition with energy gap of 3.12 eV with no effect of the low energy Ar + ion beam. The values of the dispersion energy E d the oscillator energy E o , the lattice dielectric constant ε L and the dielectric constant at infinity wavelength ε ∞ have been determined

  9. Plasticized phenolphthalein polycarbonate

    Science.gov (United States)

    Harrison, E. S.

    1976-01-01

    Phenolphthalein polycarbonate was successfully plasticized with polychlorinated biphenyls (e.g., Aroclor 1231) or tricresyl phosphate and cast from tetrahydrofuran to give clear films without loss of fire resistance. At loadings of 20 to 30 percent plasticizer the Tg was lowered to approximately 100 C which would render phenolphthalein polycarbonate easily moldable. Although these materials had some mechanical integrity as shown by their film forming ability, the room temperature toughness of the plasticized polymer was not significantly improved over unmodified polymer.

  10. Effects of gamma irradiation on optical properties of polycarbonate: different formulations with commercial stabilizers

    International Nuclear Information System (INIS)

    Ferreira, Carlas C.; Aquino, Katia Aparecida da S.; Araujo, Elmo S.

    2009-01-01

    Medical plastics are in general sterilized by gamma irradiation in doses of 25 kGy. However, this process often causes discoloration of the product due the formation of color centers during the irradiation. In particular, polycarbonate (PC), a transparent thermoplastic, when gamma-irradiated undergoes main chain scissions with consequent yellowness. This discoloration is attributed the formation of macroradicals type phenoxyl and phenyl produced by irradiation process. PC was prepared in formulations containing different stabilizers in order to investigate its optical properties (transmittance and yellowness index) changed by irradiation process. Among the stabilizers tested, a new commercial stabilizer (high performance phosphite) has presented good results concerning to reduction of the yellowness in irradiated specimen tests. Transmittance (at 420 nm) of irradiated samples at doses of 25 kGy decreases to ∼ 45% of non-irradiated sample value, immediately to the irradiation process. Nevertheless, this transmittance is increased to values of ∼ 70% of non-irradiated sample, after 60 hours under heating into oven (45 deg C). (author)

  11. On the effect of the fiber orientation on the flexural stiffness of injection molded short fiber reinforced polycarbonate plates

    NARCIS (Netherlands)

    Neves, N.M.; Isdell, G.; Pouzada, A.S.; Powell, P.C.

    1998-01-01

    The through-thickness fiber orientation distribution of injection molded polycarbonate plates was experimentally determined by light reflection microscopy and manual digitization of polished cross sections. Fiber length distribution was determined by pyrolysis tests followed by image analysis. A

  12. Effects of Phase Separation Behavior on Morphology and Performance of Polycarbonate Membranes.

    Science.gov (United States)

    Idris, Alamin; Man, Zakaria; Maulud, Abdulhalim S; Khan, Muhammad Saad

    2017-04-05

    The phase separation behavior of bisphenol-A-polycarbonate (PC), dissolved in N -methyl-2-pyrrolidone and dichloromethane solvents in coagulant water, was studied by the cloud point method. The respective cloud point data were determined by titration against water at room temperature and the characteristic binodal curves for the ternary systems were plotted. Further, the physical properties such as viscosity, refractive index, and density of the solution were measured. The critical polymer concentrations were determined from the viscosity measurements. PC/NMP and PC/DCM membranes were fabricated by the dry-wet phase inversion technique and characterized for their morphology, structure, and thermal stability using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis, respectively. The membranes' performances were tested for their permeance to CO₂, CH₄, and N₂ gases at 24 ± 0.5 °C with varying feed pressures from 2 to 10 bar. The PC/DCM membranes appeared to be asymmetric dense membrane types with appreciable thermal stability, whereas the PC/NMP membranes were observed to be asymmetric with porous structures exhibiting 4.18% and 9.17% decrease in the initial and maximum degradation temperatures, respectively. The ideal CO₂/N₂ and CO₂/CH₄ selectivities of the PC/NMP membrane decreased with the increase in feed pressures, while for the PC/DCM membrane, the average ideal CO₂/N₂ and CO₂/CH₄ selectivities were found to be 25.1 ± 0.8 and 21.1 ± 0.6, respectively. Therefore, the PC/DCM membranes with dense morphologies are appropriate for gas separation applications.

  13. Effects of Phase Separation Behavior on Morphology and Performance of Polycarbonate Membranes

    Directory of Open Access Journals (Sweden)

    Alamin Idris

    2017-04-01

    Full Text Available The phase separation behavior of bisphenol-A-polycarbonate (PC, dissolved in N-methyl-2-pyrrolidone and dichloromethane solvents in coagulant water, was studied by the cloud point method. The respective cloud point data were determined by titration against water at room temperature and the characteristic binodal curves for the ternary systems were plotted. Further, the physical properties such as viscosity, refractive index, and density of the solution were measured. The critical polymer concentrations were determined from the viscosity measurements. PC/NMP and PC/DCM membranes were fabricated by the dry-wet phase inversion technique and characterized for their morphology, structure, and thermal stability using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis, respectively. The membranes’ performances were tested for their permeance to CO2, CH4, and N2 gases at 24 ± 0.5 °C with varying feed pressures from 2 to 10 bar. The PC/DCM membranes appeared to be asymmetric dense membrane types with appreciable thermal stability, whereas the PC/NMP membranes were observed to be asymmetric with porous structures exhibiting 4.18% and 9.17% decrease in the initial and maximum degradation temperatures, respectively. The ideal CO2/N2 and CO2/CH4 selectivities of the PC/NMP membrane decreased with the increase in feed pressures, while for the PC/DCM membrane, the average ideal CO2/N2 and CO2/CH4 selectivities were found to be 25.1 ± 0.8 and 21.1 ± 0.6, respectively. Therefore, the PC/DCM membranes with dense morphologies are appropriate for gas separation applications.

  14. Studies on the effect of compatibilizers on mechanical, thermal and flow properties of polycarbonate/poly (butylene terephthalate) blends

    Science.gov (United States)

    Kumar, Ravindra; Kar, Kamal K.; Kumar, Vijai

    2018-01-01

    Bisphenol-A polycarbonate (PC) and poly(butylene terephthalate) (PBT) were melt blended with ethylene-n-butylacrylate-glycidylmethacrylate terpolymer (E-BA-GMA) at various proportions in order to study the effects of compatibilizers on mechanical, thermal and flow properties of blends. Furthermore, on the basis of this study, PC and PBT were melt-blended at 60/40 proportion with three different compatibilizers viz., ethylene-n-butylacrylate copolymer (E-BA), E-BA-GMA and random copolymer of ethylene and glycidylmethacrylate (E-GMA) at 3 phr loading in a co-rotating twin screw extruder. Tensile, flexural and impact tests were carried out on injection molded samples of PC/PBT blends. The notched izod impact strength increases enormously (˜2-3 times) on addition of any one of the three compatibilizers, and elongation at break (%) also improves tremendously (3, 5 and 4 times) on incorporation of E-BA, E-BA-GMA and E-GMA copolymer, respectively while other mechanical properties decreases slightly (3%-8%) on addition of any one of these compatibilizers. The heat deflection temperature (HDT) raises ˜8 °C-9 °C on addition of either E-BA-GMA or E-GMA, while E-BA shows a negative effect on HDT. The melt flow index diminishes significantly (˜5%-20%) on incorporation of these compatibilizers. The morphology studies via scanning electron microscopy of these four blends were carried out to confirm the mechanical results.

  15. Evidence of blocking effects on 3-keV Ne7+ ions guided through nanocapillaries in polycarbonate

    International Nuclear Information System (INIS)

    Stolterfoht, N.; Hellhammer, R.; Sulik, B.; Juhasz, Z.; Bayer, V.; Trautmann, C.; Bodewits, E.; Hoekstra, R.

    2011-01-01

    We studied the dynamic properties of ion guiding through nanocapillaries etched in insulating polycarbonate (PC). Capillaries with diameters of 95 and 165 nm and a length of 10 μm were used. In a further sample, the capillaries had a diameter of 175 nm and a length of 30 μm. A few additional measurements were made using capillaries in polyethylene terephthalate (PET). The temporal evolution of the intensity and the angular distribution of the transmitted ions were studied by measuring transmission profiles as a function of the charge deposited on the sample surface. The tilt angle of the capillary axis was varied from 0 deg. to 5 deg. The mean emission angle of the transmission profiles exhibit pronounced oscillations, similarly as in previous measurements using PET. However, for PC, nearly an order of magnitude more charge needs to be inserted into the capillaries to accomplish the oscillations. In contrast to PET, with PC, we observed a strong decrease of the profile intensities with irradiation time. This observation provides evidence of blocking effects on the ions, which are likely to be due to a repulsive field produced by significant charge deposition inside the PC capillaries.

  16. Biodegradable cationic poly(carbonates): Effect of varying side chain hydrophobicity on key aspects of gene transfection.

    Science.gov (United States)

    Ong, Zhan Yuin; Yang, Chuan; Cheng, Wei; Voo, Zhi Xiang; Chin, Willy; Hedrick, James L; Yang, Yi Yan

    2017-05-01

    The degree of hydrophobicity in cationic polymers plays an important but often underappreciated role in the safety and efficacy of gene delivery processes. In order to further elucidate structure-activity relationships of biodegradable cationic poly(carbonate) gene carriers, we synthesized a series of narrowly dispersed homo-polymers via metal-free organocatalytic living ring-opening polymerization (ROP) of cyclic carbonate monomers bearing either alkyl (propyl, hexyl or nonyl) or 4-methyl benzyl halide side chains. The polymers were then quaternized using bis-tertiary amines to install both quaternary ammoniums and tertiary amines for DNA binding and endosomal escape, respectively. Among the polymers with similar molecular lengths and charge densities, it was found that an increase in side chain alkyl spacer length from 3 to 6 carbons significantly enhanced cellular uptake and luciferase gene expression in HepG2 and HeLa cell lines without causing overt hemolysis and cytotoxicity. A further increase of side chain alkyl length to 9 carbons, however, led to a drastic decline in gene expression due to increased cellular toxicity, which was correlated with an increased disruption and lysis of red blood cell membranes. Interestingly, the incorporation of an aromatic 4-methyl benzyl spacer increased DNA binding strength, reduced particle sizes of resultant DNA complexes, and enhanced cellular uptake, leading to improved luciferase gene expression, albeit with higher levels of hemolysis and cytotoxicity. Taken together, the findings of this study demonstrate that a delicate balance between cationic charge density and hydrophobicity could be achieved by utilizing a hexyl spacer in the side chains of cationic poly(carbonates), hence providing insights on the future development of non-viral cationic polymeric gene delivery systems. Owing to their ease of synthesis and well-controlled polymerization, biodegradable cationic poly(carbonates) have emerged as a highly promising

  17. Evaluation of frictional forces of polycarbonate self-ligating brackets.

    Science.gov (United States)

    Fernandes, Daniel J; Miguel, José Augusto M; Quintão, Catia C A; Elias, Carlos N

    2010-01-01

    To evaluate the frictional forces generated by ceramic- (Opal, Ultradent) and glass-fiber-reinforced polycarbonate self-ligating brackets (Oyster, Gestenco) and compare the effectiveness of these ligatureless systems with glass-fiber-reinforced polycarbonate conventional brackets (Blonde, Gestenco). The hypothesis is that there is no difference between frictional forces generated by ceramic- and glass-fiber-reinforced polycarbonate self-ligating and glass-fiber-reinforced polycarbonate conventional brackets. Twelve preadjusted 0.022 3 0.028-inch maxillary canine brackets were tested, divided into three groups: Opal, Oyster, and Blonde. Frictional tests were conducted with the Emic DL 10000 testing machine with a 20 N loadcell for 40 seconds at a 0.5 cm/min speed. Each bracket-wire combination was tested five times. The data generated were analyzed by parametric analysis of variance (one-way ANOVA) and Bonferroni tests. Analysis of variance indicated significant differences for the three groups (Pfrictional forces of the Oyster glass-fiber-reinforced polycarbonate self-ligating brackets were significantly lower (37.0 ± 8.9 cN) than those of the Opal ceramic-reinforced polycarbonate self-ligating brackets (49.5 ± 10.1 cN), while the Blonde glass-fiber-reinforced conventional bracket frictional forces were 105.8 ± 6.4 cN. Oyster glass-fiber-reinforced polycarbonate brackets produced less friction than Opal ceramic-reinforced polycarbonate brackets. The polycarbonate ligatureless system showed significantly lower frictional forces compared to Blonde conventional polycarbonate brackets tied with elastomeric ligatures. The study rejected the initial hypothesis because there are significant differences of frictional forces among the tested systems. © 2010 BY QUINTESSENCE PUBLISHING CO, INC.

  18. Gelatin functionalization with tyrosine derived moieties to increase the interaction with hydroxyapatite fillers.

    Science.gov (United States)

    Neffe, Axel T; Loebus, Axel; Zaupa, Alessandro; Stoetzel, Christian; Müller, Frank A; Lendlein, Andreas

    2011-04-01

    Combining gelatins functionalized with the tyrosine-derived groups desaminotyrosine or desaminotyrosyl tyrosine with hydroxyapatite (HAp) led to the formation of composite materials with much lower swelling ratios than those of the pure matrices. Shifts of the infra-red (IR) bands related to the free carboxyl groups could be observed in the presence of HAp, which suggested a direct interaction of matrix and filler that formed additional physical cross-links in the material. In tensile tests and rheological measurements the composites equilibrated in water had increased Young's moduli (from 200 kPa up to 2 MPa) and tensile strengths (from 57 kPa up to 1.1 MPa) compared with the matrix polymers without affecting the elongation at break. Furthermore, an increased thermal stability of the networks from 40 to 85°C could be demonstrated. The differences in the behaviour of the functionalized gelatins compared with pure gelatin as a matrix suggested an additional stabilizing bond between the incorporated aromatic groups and the HAp as supported by the IR results. The composites can potentially be applied as bone fillers. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  19. Tyrosine-derived novel antimicrobial hydantoin polymers: synthesis and evaluation of anti-bacterial activities.

    Science.gov (United States)

    Ravichandran, Vasanthan; Rai, Rajani Kant; Kesavan, Venkitasamay; Jayakrishnan, A

    2017-12-01

    A new approach for the design and synthesis of cyclic N-halamine polymers having anti-bacterial activity based on a vinyl derivative of tyrosine-derived hydantoin is reported. The synthesis of N-halamine polymers generally involves the chemical modification of 5,5'-disubstituted hydantoin to introduce polymerizable vinyl moieties thereby restricting the halogen capture only on the amide nitrogen. Here we show the possibility of synthesizing vinyl monomers of N-halamine from α-amino acids wherein both the amide and imide nitrogens are available for halogen capture. Thus, a hydantoin monomer was synthesized from L-tyrosine and copolymerized with methyl methacrylate and 2-(hydroxyethyl)methacrylate, to obtain random co-polymers. The monomer and its co-polymers were characterized using NMR, IR, HRMS, GPC, DSC, EDAX and TGA analysis. Films of the co-polymers cast from 10% acetone solutions were exposed to sodium hypochlorite solution to activate the hydantoin moieties. The oxidative chlorine content of the films ranged from 0.6 to 0.9%. The activated films were exposed to both Gram positive (S. aureus) and Gram negative (E. coli) bacteria using standard protocols. Polymers having chlorine content as little as 0.6% exhibited 6 log reduction in the bacterial growth within 30 min of exposure. The method allows the halogenation of both amide and imide nitrogens and could be applied to the preparation of a number of vinyl hydantoins from many amino acids.

  20. DLC-Si protective coatings for polycarbonates

    Directory of Open Access Journals (Sweden)

    Damasceno J.C.

    2003-01-01

    Full Text Available In this work, a-C:H:Si (DLC-Si films were produced onto crystalline silicon and polycarbonate substrates by the rf-PACVD technique from gaseous mixtures of CH4 + SiH4 and C2H2 + SiH4. The effects of self-bias and gas composition upon mechanical and optical properties of the films were investigated. Micro-hardness, residual stress, surface roughness and refractive index measurements were employed for characterization. By incorporating low concentrations of silicon and by exploring the more favorable conditions for the rf-PACVD deposition technique, highly adherent DLC-Si thin films were produced with reduced internal stresses (lower than 1 GPa, high hardness (around 20 GPa and high deposition rates (up to 10 µm/h. Results that show the technological viability of this material for application as protective coatings for polycarbonates are also discussed.

  1. Synthesis of polycarbonate urethane elastomers and effects of the chemical structures on their thermal, mechanical and biocompatibility properties.

    Science.gov (United States)

    Zhu, Rong; Wang, Yiyu; Zhang, Zongrui; Ma, Daiwei; Wang, Xinyu

    2016-06-01

    In this study, to obtain biomedical polyurethane elastomers with good mechanical properties and biocompatibility, a series of polycarbonate urethanes were synthesized via a two-step solution of polymerization method using the poly(1,6-hexanediol)carbonate diols (PCDL) as the soft segment, 4,4'-methylenebis(cyclohexyl isocyanate) (H12MDI), 1,6-hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) as the hard segment with dibutyltin dilaurate as the catalyst. In this article, we illustrated the physical behaviors were obviously influenced by synthetic routes. And their chemical and physical structures were investigated by gel permeation chromatograph (GPC), differential scanning calorimeter (DSC), fourier transform infrared spectrography (FT-IR) and mechanical properties tests. The surface wettability were studied by contact angle measurement (CA). As a kind of short-term implant biomaterial, the results of the hemolysis and platelet adhesive tests were recorded by spectrophotometer and scanning electron microscopy (SEM), indicating the materials have a great potential for developments and applications in biomedical field.

  2. Synthesis of polycarbonate urethane elastomers and effects of the chemical structures on their thermal, mechanical and biocompatibility properties

    Directory of Open Access Journals (Sweden)

    Rong Zhu

    2016-06-01

    Full Text Available In this study, to obtain biomedical polyurethane elastomers with good mechanical properties and biocompatibility, a series of polycarbonate urethanes were synthesized via a two-step solution of polymerization method using the poly(1,6-hexanediolcarbonate diols (PCDL as the soft segment, 4,4′-methylenebis(cyclohexyl isocyanate (H12MDI, 1,6-hexamethylene diisocyanate (HDI and 1,4-butanediol (BDO as the hard segment with dibutyltin dilaurate as the catalyst. In this article, we illustrated the physical behaviors were obviously influenced by synthetic routes. And their chemical and physical structures were investigated by gel permeation chromatograph (GPC, differential scanning calorimeter (DSC, fourier transform infrared spectrography (FT-IR and mechanical properties tests. The surface wettability were studied by contact angle measurement (CA. As a kind of short-term implant biomaterial, the results of the hemolysis and platelet adhesive tests were recorded by spectrophotometer and scanning electron microscopy (SEM, indicating the materials have a great potential for developments and applications in biomedical field.

  3. Percolation Threshold in Polycarbonate Nanocomposites

    Science.gov (United States)

    Ahuja, Suresh

    2014-03-01

    Nanocomposites have unique mechanical, electrical, magnetic, optical and thermal properties. Many methods could be applied to prepare polymer-inorganic nanocomposites, such as sol-gel processing, in-situ polymerization, particle in-situ formation, blending, and radiation synthesis. The analytical composite models that have been put forth include Voigt and Reuss bounds, Polymer nanocomposites offer the possibility of substantial improvements in material properties such as shear and bulk modulus, yield strength, toughness, film scratch resistance, optical properties, electrical conductivity, gas and solvent transport, with only very small amounts of nanoparticles Experimental results are compared against composite models of Hashin and Shtrikman bounds, Halpin-Tsai model, Cox model, and various Mori and Tanaka models. Examples of numerical modeling are molecular dynamics modeling and finite element modeling of reduced modulus and hardness that takes into account the modulus of the components and the effect of the interface between the hard filler and relatively soft polymer, polycarbonate. Higher nanoparticle concentration results in poor dispersion and adhesion to polymer matrix which results in lower modulus and hardness and departure from the existing composite models. As the level of silica increases beyond a threshold level, aggregates form which results in weakening of the structure. Polymer silica interface is found to be weak as silica is non-interacting promoting interfacial slip at silica-matrix junctions. Our experimental results compare favorably with those of nanocomposites of polyesters where the effect of nanoclay on composite hardness and modulus depended on dispersion of nanoclay in polyester.

  4. Monte Carlo simulations of radioactive waste encapsulated by bisphenol-A polycarbonate and effect of bismuth-III oxide filler material

    Science.gov (United States)

    Özdemir, Tonguç

    2017-06-01

    Radioactive waste generated from the nuclear industry and non-power applications should carefully be treated, conditioned and disposed according to the regulations set by the competent authority(ies). Bisphenol-a polycarbonate (BPA-PC), a very widely used polymer, might be considered as a potential candidate material for low level radioactive waste encapsulation. In this work, the dose rate distribution in the radioactive waste drum (containing radioactive waste and the BPA-PC polymer matrix) was determined using Monte Carlo simulations. Moreover, the change of mechanical properties of BPA-PC was estimated and their variation within the waste drum was determined for the periods of 15, 30 and 300 years after disposal to the final disposal site. The change of the dose rate within the waste drum with different contents of bismuth-III oxide were also simulated. It was concluded that addition of bismuth-III oxide filler decreases the dose delivered to the polymeric matrix due to photoelectric effect.

  5. Mechanical Properties and Morphological Changes of Poly(lactic acid)/Polycarbonate/Poly(butylene adipate-co-terephthalate) Blend Through Reactive Processing—Effects of Fabrication Processes—

    Science.gov (United States)

    Kanzawa, Takeshi; Tokumitsu, Katsuhisa

    The mechanical properties of poly(lactic acid) (PLA)/polycarbonate (PC) blend were improved considerably by addition of both poly(butylene adipate-co-terephthalate) (PBAT) and dicumyl peroxide (DCP) as a radical coupling agent for PLA and PBAT. In this work, the authors aimed to grasp meltdown properties of PLA/PBAT with/without DCP by (1) clarifying the effect of addition of DCP on the melt viscoelatsic properties of PLA/PBAT, and make this ternary system more suitable by (2) optimizing additive contents and (3) investigating the effect of fabrication processes on mechanical properties and morphologies of the blends. The growth curves of G' and G'' for PLA/PBAT (70/30) (wt/wt) with/without DCP measured by a rheometer suggested that branching and cross-linking structures were formed by hetero-and/or homogeneous radical coupling reactions. The elongation at break of the ternary reactive blend with DCP 0.30 phr (PLA/PBAT/PC blend with DCP) increased up to 160%, which was much better than that with other DCP contents. Moreover, the value of standard deviation for the ternary reactive blend was smaller. Furthermore, PLA/PBAT/PC ternary polymer blends were prepared through a twin-screw extruder with an L/D ratio of 75, and their physical and meltdown properties were investigated. The domain size of the reactive blend with an L/D ratio of 75 was smaller than that of 45, however, the impact strength of the blend with an L/D ratio of 75 decreased with increasing rotation speed of the extruder. Moreover, the MFR of the blend increased with increasing rotation speed of the extruder as well. As the MFR of PC prepared under same condition of blending did not change, so this suggested that PLA/PBAT components of the ternary blends were degraded in higher shear rate. As a result, the impact strength of the ternary blends decreased as well.

  6. Pd-Catalyzed Dimethylation of Tyrosine-Derived Picolinamide for Synthesis of (S)-N-Boc-2,6-dimethyltyrosine and Its Analogues.

    Science.gov (United States)

    Wang, Xuning; Niu, Songtao; Xu, Lanting; Zhang, Chao; Meng, Lingxing; Zhang, Xiaojing; Ma, Dawei

    2017-01-06

    A short and efficient synthesis of (S)-N-Boc-2,6-dimethyltyrosine utilizing palladium-catalyzed directed C-H functionalization is described. This represents the first general method for the ortho-dimethylation of tyrosine derivatives and offers a practical approach for preparing this synthetically important building block. Notably, throughout the reaction sequence no racemization occurs at the susceptible α-chiral centers.

  7. The effects of multiple thermomechanical cycles on the chemical and physical properties, morphology, and mechanical properties of a polycarbonate/ABS blend

    Science.gov (United States)

    Sloop, Charles Clayton, III

    A commercial blend of Polycarbonate (PC) and Acrylonitrile-Butadiene-Styrene (ABS) was subjected to five thermomechanical processing cycles. The virgin resin was characterized by a number of techniques; Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), Thermogravometric Analysis (TGA), Gel Permeation Chromatography (GPC) and Melt Flow (MFI) to determine the initial chemical and physical properties. Model resins of the PC/ABS components were also characterized by these techniques. A sequential extraction procedure was developed to isolate the PC, free Styrene-Acrylonitrile copolymer (SAN), and SAN-graft-Polybutadiene (SAN-g-PB) components for individual analysis. After each thermomechanical cycle, the PC/ABS blend was analyzed to determine the effect of the additional processing cycle. Individual components were also analyzed after each cycle. Through five thermomechancial processing cycles, the major effects on the PC/ABS were degradation of the SAN-graft-Polybutadiene rubber by crosslinking and chain scission reactions and chain scission of the SAN copolymer due to thermal degradation and mechanical shearing. The crosslinking reaction of the SAN-g-PB was monitored by FT-IR, DSC, and TGA of the isolated SAN-g-PB while chain-scission reactions were monitored by FT-IR and TGA. Chain scission of the SAN copolymer was monitored by GPC molecular weight determinations of the isolated SAN fraction. PC/ABS morphology was analyzed by Scanning and Transmission Electron Microscopy (SEM, TEM) and by a novel new technique, X-ray Absorption Near Edge Spectrocopy (XANES) that utilizes chemical specificity in the carbon K-shell absorption edge to provide phase contrast. The PC/ABS morphology consisted of a fine dispersion of ABS domains of 750-800 nm average diameter in the bulk morphology of the blend. Near the specimen surface, extended threadlike ABS domains were observed. The morphology as a result of thermomechanical cycling was analyzed qualitatively by

  8. THERMAL properties and morphology of Polypropylene/Polycarbonate/Polypropylene-Graft-Maleic anhydride blends

    OpenAIRE

    Mat-Shayuti M. S.; Abdullah M. Z.; Megat-Yusoff P. S. M.

    2016-01-01

    This work investigates the effect of blending polycarbonate (PC) into polypropylene (PP) matrix polymer on thermal properties and morphology. The blends, containing 5% to 35% of polycarbonate and 5% compatibilizer, were compounded using twin-screw extruder and fabricated into standard tests samples using injection or compression molding. The compatibilizer used was polypropylene-graft-maleic anhydride (PP-g-MA). Thermogravimetric analysis (TGA) showed improved thermal degradation temperature ...

  9. Preparation and characterization of polycarbonate/multiwalled carbon nanotube nanocomposites.

    Science.gov (United States)

    Larosa, Claudio; Patra, Niranjan; Salerno, Marco; Mikac, Lara; Merijs Meri, Remo; Ivanda, Mile

    2017-01-01

    A polymer nanocomposite was produced by ultrasonic-assisted dispersion of multiwalled carbon nanotubes (MWCNTs) in a polycarbonate matrix using p -xylene and dichloromethane as the solvents. The filler loading was varied from 1 to 3 wt % in order to examine the effect of MWCNTs on the structure and properties of the composites. The nanocomposites were characterized by DSC, DTA, TGA, UV-vis, FTIR and Raman spectroscopy to evaluate the changes induced by the filler in the polymer matrix. UV-vis, FTIR and Raman spectroscopy measurements confirmed the presence of the dispersed phase in the composite films, while TGA and DSC analysis of the nanocomposites revealed enhanced thermal stability and decreased crystallinity, respectively, as compared to the neat polymer. The proposed composites can find application in a number of everyday products where polycarbonate is the base polymer.

  10. Preparation and characterization of polycarbonate/multiwalled carbon nanotube nanocomposites

    Directory of Open Access Journals (Sweden)

    Claudio Larosa

    2017-09-01

    Full Text Available A polymer nanocomposite was produced by ultrasonic-assisted dispersion of multiwalled carbon nanotubes (MWCNTs in a polycarbonate matrix using p-xylene and dichloromethane as the solvents. The filler loading was varied from 1 to 3 wt % in order to examine the effect of MWCNTs on the structure and properties of the composites. The nanocomposites were characterized by DSC, DTA, TGA, UV–vis, FTIR and Raman spectroscopy to evaluate the changes induced by the filler in the polymer matrix. UV–vis, FTIR and Raman spectroscopy measurements confirmed the presence of the dispersed phase in the composite films, while TGA and DSC analysis of the nanocomposites revealed enhanced thermal stability and decreased crystallinity, respectively, as compared to the neat polymer. The proposed composites can find application in a number of everyday products where polycarbonate is the base polymer.

  11. Effect of telechelic ionic groups on the dispersion of organically modified clays in bisphenol A polycarbonate nanocomposites by in-situ polymerization using activated carbonates

    Directory of Open Access Journals (Sweden)

    M. Colonna

    2017-05-01

    Full Text Available Nanocomposites of bisphenol A polycarbonate with organically modified clays have been prepared for the first time by in-situ polymerization using bis(methyl salicyl carbonate as activated carbonate. The use of the activated carbonate permits to conduct the polymerization reaction at lower temperature and with shorter polymerization time with respect to those necessary for traditional melt methods that uses diphenyl carbonate, affording a nanocomposite with improved color. Moreover, an imidazolium salt with two long alkyl chains has been used to modify the montmorillonite, providing an organically modified clay with high thermal stability and wide d-spacing. The addition of ionic groups at the end of the polymer chain increases the interaction between the clay surface and the polymer producing a better dispersion of the clay. The presence of the clay increases the thermal stability of the polymer.

  12. Radiolytic stabilization on optical properties of polycarbonate

    International Nuclear Information System (INIS)

    Ferreira, Carlas P.R.C.; Araujo, Elmo S.; Aquino, Katia A.S.

    2011-01-01

    Polycarbonate (PC) is an engineering plastic widely used in several industrial segments. However, in medical applications, this material is required to be sterilized by ionizing radiation in doses of 25kGy. PC, when gamma irradiated, undergoes main chain scissions with consequent formation of phenoxy and phenyl radicals. The former remains trapped into the polymer matrix causing undesirable yellowness on material at room temperature. A strategy to minimize such effect is to incorporate additives into the polymer system enabling efficient phenoxy radicals and secondary electrons scavenging. Our results show that, in absorbed dose of 25kGy, change in yellowness index (ΔΥI) decreases from 15.6 to 3.9 for PC containing 0.8% of additives. The color differences (ΔE *) between the non-irradiated sample and that irradiated at 25kGy were 2.4 and 9.8, for PC with additive and PC control, respectively. Mechanical properties of gamma-irradiated PC were also evaluated and showed no significant change, even without stabilizing additives. Thus, this work establishes a new PC formulation stable to gamma irradiation at sterilizing absorbed doses. (author)

  13. Diffusional enhancement of holograms: phenanthrenequinone in polycarbonate

    Science.gov (United States)

    Veniaminov, Andrei; Bartsch, Eckhard

    2002-07-01

    As a further development of the manufacture of holographic gratings by the diffusion of phenanthrenequinone in polymer glass, the traditionally employed poly(methyl methacrylate) is replaced by poly(bisphenol-A-carbonate). The post-exposure growth and decay of the gratings in the two materials are compared at different spatial periods and temperatures. The medium with polycarbonate demonstrates a fortunate combination of significantly improved stability of the gratings and their faster development. Our results indicate that the polycarbonate materials promise to be suitable media for holographic optical elements and data storage.

  14. The Effect of Oxygen-Plasma Treated Graphene Nanoplatelets upon the Properties of Multiwalled Carbon Nanotube and Polycarbonate Hybrid Nanocomposites Used for Electrostatic Dissipative Applications

    Directory of Open Access Journals (Sweden)

    Akkachai Poosala

    2015-01-01

    Full Text Available Oxygen-plasma treated graphene nanoplatelet (OGNP, multiwalled carbon nanotube (MWCNT and polycarbonate (PC hybrid nanocomposites were prepared via a melting process using a twin-screw extruder. The contents of the OGNPs were in the range of 0.0 to 5.0 parts per hundred resin (phr, whilst the dosage of MWCNTs was kept at a constant of 2.0 wt%. Nanocomposites containing 2.0 wt% of MWCNTs and mixtures of 2.0 wt% of MWCNTs at 1.5 to 5.0 phr of OGNPs had tribocharged voltages, surface resistivities, and decay times, all within the electrostatic discharge (ESD specification. The X-ray diffraction (XRD and scanning electron microscopy (SEM results revealed that the OGNPs slightly intercalated and distributed also within the PC matrix. The glass transition temperature Tg and heat capacity jump, at the glass transition stages of nanocomposite, slightly changed, as the contents of the OGNPs increased. The melt flow index (MFI of nanocomposites significantly decreased when MWCNTs were added to the PC resin and slightly changed as the dosage of OGNPs was increased. Tensile Young’s modulus of nanocomposites tended to increase, as the elongation at break and impact strength decreased, when OGNP concentrations were increased. This research work exhibited that OGNP/MWCNT/PC hybrid nanocomposites do indeed have the potential to be used in ESD applications.

  15. Co-continuous polycarbonate/ABS blends

    NARCIS (Netherlands)

    Inberg, J.P.F.; Gaymans, R.J.

    2002-01-01

    Co-continuous PC/ABS (50/50) blends were studied with a variable polybutadiene (PB) content (0–40%) in ABS. Polycarbonate (PC), styrene-acrylonitrile (SAN) and PB were blended in two steps using a twin screw extruder. Rectangular bars were injection moulded and notched Izod impact tested at

  16. Technical feasibility study on polycarbonate solar panels

    NARCIS (Netherlands)

    Hackmann, M.M.; Meuwissen, M.H.H.; Bots, T.L.; Buijs, J.A.H.M.; Broek, K.M.; Kinderman, R.; Tanck, O.B.F.; Schuurmans, F.M.

    2004-01-01

    This paper describes a technical feasibility study on the application of polycarbonate (PC) plates in a superstrate photovoltaic module design. The lamination process was performed in a conventional laminator apparatus using low temperature curing (100°C) ethylene-vinyl-acetate (EVA) as the potting

  17. Spectroscopic investigations on ion beam irradiated polycarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Puglisi, O.; Chipara, M. E-mail: mchipara@unlserve.unl.edu; Enge, W.; Compagnini, G.; Reyes-Romero, J. E-mail: vetr@caracas.c-com.net; Bacmeister, U.; Chipara, M.D

    2000-05-02

    Luminescence investigations on polycarbonate irradiated with accelerated uranium ions are reported. The dependence of luminescence spectra on the penetration length, deposited energy and dose and track radius is investigated. The luminescence spectrum has been assigned to phenyls. It is suggested that most phenyls are located within the latent track. The experimental results are in good agreement with data obtained by electron spin resonance spectroscopy.

  18. Diamond-like carbon films deposited on polycarbonates by plasma-enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Guo, C.T.

    2008-01-01

    Diamond-like carbon films were coated on optical polycarbonate using plasma-enhanced chemical vapor deposition. A mixture of SiH 4 and CH 4 /H 2 gases was utilized to reduce the internal compressive stress of the deposited films. The structure of the DLC films was characterized as a function of film thickness using Raman spectroscopy. The dependence of G peak positions and the intensity ratio of I D /I G on the DLC film thicknesses was analyzed in detail. Other studies involving atomic force microscopy, ultraviolet visible spectrometry, and three adhesion tests were conducted. Good transparency in the visible region, and good adhesion between diamond-like carbon films and polycarbonate were demonstrated. One-time recordings before and after a DLC film was coated on compact rewritable disc substrates were analyzed as a case study. The results reveal that the diamond-like carbon film overcoating the optical polycarbonates effectively protects the storage media

  19. Synergistic effect of selectively distributed AlN/MWCNT hybrid fillers on the morphological, mechanical and thermal properties of polycarbonate/maleated poly[styrene-b-(ethylene-co-butylene)- b-styrene] triblock copolymer (SEBS-g-MA) composites

    Science.gov (United States)

    Xiao, Chao; Leng, Xinyu; Wang, Hui; Su, Zheng; Zhang, Xian; Chen, Lin; Zheng, Kang; Tian, Xingyou

    2017-02-01

    A quaternary nanocomposite polycarbonate (PC)- multi-walled carbon nanotubes (MWCNT)/SEBS-g-MA (SM)-AlN is prepared by controlling the selective distribution of nano-fillers via melt-blending. Through a two-step mixing method, surface modified AlN is selectively dispersed in the island-like SM phase; meanwhile, MWCNT acting as bridges are mainly located in the continuous phase of PC. This ‘island-bridge’ morphology is confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The selective localization results agree well with the theoretical predictions. Dynamic mechanical analysis (DMA) indicates that the addition of hybrid fillers improved the storage modulus selectively. Thermogravimetric analysis (TGA) shows that the thermal stability of the PC/SM blends increased significantly; the degradation kinetic has also been changed due to the synergistic effects of the fillers. This novel ‘island-bridge’ network contributes a higher thermal conductivity at low filler content as the effective thermal conductivity reached 0.72 W m-1 K-1, which is three times higher than that of 70PC/30SM. The experimental observations coincide well with the optimizing model results.

  20. Radiolytic degradation and stability of polycarbonate

    International Nuclear Information System (INIS)

    Araujo, E.S. de.

    1993-01-01

    The radiolytic stability of polycarbonate was studied using national commercial additives, employed in the photo and thermo-oxidative stabilization of polymers. Among several additives tested only two showed the efficiency to radiolytic protection: one quencher and one radical scavenger. It was derived a linear relation that provides by slope of the straight line the degree of degradation (scissions), G, and the factors of radiolytic protection P (degree of protection) and CE (capture of energy) conferred by radioprotector additive easily. Therefore the method developed in this work (viscosity) to study the molecular degradation and stability of polymers is a simply and precise method. The synergic mixture of two additives (1% of weight total) confers at polycarbonate excellent radiolytic protection of 98% (20 - 40 kGy) reducing the G value of 16.7 to only 0.4. (author). 69 refs, 31 figs, 17 tabs

  1. Polycarbonate and co-continuous polycarbonate/ABS blends: influence of specimen thickness

    NARCIS (Netherlands)

    Inberg, J.P.F.; Gaymans, R.J.

    2002-01-01

    The influence of specimen thickness on the fracture behaviour of polycarbonate (PC) and co-continuous PC/ABS (50/50) blends was studied in single edge notch tensile tests at 1 m/s and different temperatures (−80 to 130 °C). Specimen thickness ranged from 0.1 to 8 mm. In the co-continuous PC/ABS

  2. Polycarbonate and co-continuous polycarbonate/ABS blends: influence of notch radius

    NARCIS (Netherlands)

    Inberg, J.P.F.; Gaymans, R.J.

    2002-01-01

    The influence of notch tip radius in the range of 1–0.002 mm was studied on polycarbonate (PC) and co-continuous PC/acrylonitrile–butadiene–styrene (ABS). Co-continuous PC/ABS blend was obtained by mixing PC and ABS containing 15% polybutadiene (PB) in a twin screw extruder. PC and PC/ABS specimens

  3. Measurements of diffusion parameters of methanol on gamma-irradiated polycarbonate

    International Nuclear Information System (INIS)

    Silva, Pietro P.J.C.G.P.O.; Araujo, Elmo S.

    2013-01-01

    Polycarbonate (PC) is an engineering polymer which presents interesting properties such as toughness, light weight and transparency. This material has been used for several important applications including in the medical field. In this particular application, polycarbonate has been exposed frequently to gamma irradiation and to chemical environment that can be able to product significant changes in polymer structure that may lead to future catastrophic fail and rupture. Polymer structural damages induced by gamma irradiation or chemical attack (environment stress cracking) have been studied by several research groups for many years and for many solvent-polymer systems, but few reporters present informations about the simultaneous occurrence of these effects. This present work has the goal to understand the diffusion process of methanol in polycarbonate and to determinate the diffusion parameters on polymer system under 100 kGy of gamma irradiation. Swelling experiments were performed at the samples of polycarbonate divided in two groups: PC-0 (without dose) and PC-100 (with 100 kGy of dose). Diffusion parameters (D) may be measured by slope of the sorption curve for polymers with Fickian behavior. A comparison of the D parameters was made for each set of sample. There were no significant differences on D values of sample groups observed due to the radiation effects. However, stress strain curves obtained show that methanol has great influence on mechanical behavior of PC but the radiation dose don't have significant influence on this mechanical behavior. (author)

  4. Measurements of diffusion parameters of methanol on gamma-irradiated polycarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Pietro P.J.C.G.P.O.; Araujo, Elmo S., E-mail: esa@ufpe.br, E-mail: pietropaolo@ipojuca.ifpe.edu.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Silveira, Leopoldo B.B. da [Highplastic Industria de Plasticos Ltda, Simoes Filho, BA (Brazil)

    2013-07-01

    Polycarbonate (PC) is an engineering polymer which presents interesting properties such as toughness, light weight and transparency. This material has been used for several important applications including in the medical field. In this particular application, polycarbonate has been exposed frequently to gamma irradiation and to chemical environment that can be able to product significant changes in polymer structure that may lead to future catastrophic fail and rupture. Polymer structural damages induced by gamma irradiation or chemical attack (environment stress cracking) have been studied by several research groups for many years and for many solvent-polymer systems, but few reporters present informations about the simultaneous occurrence of these effects. This present work has the goal to understand the diffusion process of methanol in polycarbonate and to determinate the diffusion parameters on polymer system under 100 kGy of gamma irradiation. Swelling experiments were performed at the samples of polycarbonate divided in two groups: PC-0 (without dose) and PC-100 (with 100 kGy of dose). Diffusion parameters (D) may be measured by slope of the sorption curve for polymers with Fickian behavior. A comparison of the D parameters was made for each set of sample. There were no significant differences on D values of sample groups observed due to the radiation effects. However, stress strain curves obtained show that methanol has great influence on mechanical behavior of PC but the radiation dose don't have significant influence on this mechanical behavior. (author)

  5. Synthesis of copper nanoparticles in polycarbonate by ion ...

    Indian Academy of Sciences (India)

    Administrator

    tallic particles embedded in polymers have recently gen- erated increasing interest as advanced ... disposables which are slated to be radiation sterilized. 2. Experimental. Polycarbonate samples of area 2 × 2 cm. 2 ..... The resistance of copper-polycarbonate nanocomposite synthesized at the dose of 1⋅6 × 10. 17. Cu. –.

  6. Highly Conductive Multifunctional Graphene Polycarbonate Nanocomposites

    Science.gov (United States)

    Yoonessi, Mitra; Gaier, James R.

    2010-01-01

    Graphene nanosheet bisphenol A polycarbonate nanocomposites (0.027 2.2 vol %) prepared by both emulsion mixing and solution blending methods, followed by compression molding at 287 C, exhibited dc electrical percolation threshold of approx.0.14 and approx.0.38 vol %, respectively. The conductivities of 2.2 vol % graphene nanocomposites were 0.512 and 0.226 S/cm for emulsion and solution mixing. The 1.1 and 2.2 vol % graphene nanocomposites exhibited frequency-independent behavior. Inherent conductivity, extremely high aspect ratio, and nanostructure directed assembly of the graphene using PC nanospheres are the main factors for excellent electrical properties of the nanocomposites. Dynamic tensile moduli of nanocomposites increased with increasing graphene in the nanocomposite. The glass transition temperatures were decreased with increasing graphene for the emulsion series. High-resolution electron microscopy (HR-TEM) and small-angle neutron scattering (SANS) showed isolated graphene with no connectivity path for insulating nanocomposites and connected nanoparticles for the conductive nanocomposites. A stacked disk model was used to obtain the average particle radius, average number of graphene layers per stack, and stack spacing by simulation of the experimental SANS data. Morphology studies indicated the presence of well-dispersed graphene and small graphene stacking with infusion of polycarbonate within the stacks.

  7. Factors Determining the Pore Shape in Polycarbonate Track Membranes

    CERN Document Server

    Apel, P Yu; Orelovich, O L; Akimenko, S N; Sartowska, B; Dmitriev, S N

    2004-01-01

    The process of pore formation in ion-irradiated polycarbonate films on treatment with alkali solutions in the presence of a surfactant is studied. It is found that the pore shape depends on both the structure of the initial films and the peculiarities of the interaction of the surfactant with the polymer surface and the transport of the surfactant into tracks. Due to heterogeneity of the films the cross-section of a track pore channel changes along its length. The presence of the surfactant results in a further effect. Surfactant molecules adsorb on the polymer surface at the pore entries and reduce the etch rate which leads to formation of cigar-like pore channels. The use of surfactant as a component of chemical etchant enables one to control the pore shape in track membranes thus optimizing their retention and permeation characteristics.

  8. Efficiency of Electret Polycarbonate Nonwovens in Respiratory Protection Against Nanoparticles

    Directory of Open Access Journals (Sweden)

    Brochocka Agnieszka

    2017-06-01

    Full Text Available Toxicological research on the influence of noxious nanoparticles on human health indicates the need to develop efficient protective devices. In particular, this concerns respiratory protective equipment employing filtration nonwovens. This paper presents a methodology for the improvement of the filtration efficiency of electret nonwovens against nanoparticles by enriching amorphous polycarbonate (PC with additives of different electrostatic potentials. We introduced perlite granules (positive charge and amber granules (negative charge to the polymer stream in melt-blown technology. Filtration efficiency was assessed by a standard method using paraffin oil and sodium chloride aerosol, as well as by a non-standard method using NaCl nanoparticles. The experiments showed that strengthening the effects of electrostatic forces by the introduction of modifiers is a promising approach to improving the efficiency of electret nonwovens against nanoparticles.

  9. Depth sensitivity of Lexan polycarbonate detector

    CERN Document Server

    Awad, E M

    1999-01-01

    The dependence of the registration sensitivity of Lexan polycarbonate with depth inside the detector was studied. Samples of Lexan from General Electric were irradiated to two long range ions. These were Ni and Au ions with a projectile energy of 0.3 and 1 GeV/n. Two independent techniques, the track-diameter technique (TDT) and the track profile technique (TPT), were used. The registration sensitivity was measured at depths of 7, 10, 15, 18, 20, 28, 35 and 40 mu m inside the detector. The results of the two techniques show that the detector sensitivity decreases gradually with the depth inside the detector. It reaches 20 % less compared to sensitivity at the surface after 40 mu m have been removed.

  10. Modification of polycarbonate surface in oxidizing plasma

    Science.gov (United States)

    Ovtsyn, A. A.; Smirnov, S. A.; Shikova, T. G.; Kholodkov, I. V.

    2017-11-01

    The properties of the surface of the film polycarbonate Lexan 8010 were experimentally studied after treatment in a DC discharge plasma in oxygen and air at pressures of 50-300 Pa and a discharge current of 80 mA. The contact angles of wetting and surface energies are measured. The topography of the surface was investigated by atomic force microscopy. The chemical composition of the surface was determined from the FT-IR spectroscopy data in the variant of total internal reflection, as well as X-ray photoelectron spectroscopy. Treatment in the oxidizing plasma leads to a change in morphology (average roughness increases), an increase in the surface energy, and the concentration of oxygen-containing groups (hydroxyl groups, carbonyl groups in ketones or aldehydes and in oxyketones) on the surface of the polymer. Possible reasons for the difference in surface properties of polymer under the action of oxygen and air plasma on it are discussed.

  11. Migration of bisphenol A from polycarbonate plastic of different qualities

    DEFF Research Database (Denmark)

    Pedersen, Gitte Alsing; Hvilsted, Søren; Petersen, Jens Højslev

    The study covers a review of literature and available industry information regarding release of bisphenol A from polycarbonate and the parameters affecting this bisphenol A release. Moreover in part two of the study, different samples of polycarbonate was characterised and analysed in order...... to examine the potential correlation between material specific parameters and the release of bisphenol A. It is concluded, from industry information, that only highly pure reagent grade chemicals, including additives, should be used for all polycarbonate grades to reduce photodegradation and hydrothermal...

  12. Dispersion of gold nanoclusters in TMBPA-polycarbonate by a combination of thermal embedding and vapour-induced crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Kruse, J; Dolgner, K; Greve, H; Zaporojtchenko, V; Faupel, F [Technische Fakultaet der Christian-Albrechts-Universitaet zu Kiel, Lehrstuhl fuer Materialverbunde, Kaiserstr. 2, D-24143 Kiel (Germany)

    2006-12-07

    Gold nanoclusters can be dispersed into the surface of a bisphenol-A polycarbonate film by acetone vapour induced crystallization, an effect which has been demonstrated in a previous publication of our group. Gold nanoclusters were deposited by physical vapour deposition on an amorphous thin film of polycarbonate. After vapour induced crystallization these clusters were detected by depth profiling to be embedded into the surface, with a concentration maximum in a depth of approximately 100 nm. In this work, we replaced the BPA by the modified tetramethyl bisphenol-A polycarbonate, which shows a slower crystallization kinetics. A strong enhancement of the dispersion depth has been achieved by thermal pre-embedding of the clusters into the surface. Surface analysis by means of atomic force microscopy reflects the rearrangement of polymer material in the course of crystallization.

  13. Dispersion of gold nanoclusters in TMBPA-polycarbonate by a combination of thermal embedding and vapour-induced crystallization

    Science.gov (United States)

    Kruse, J.; Dolgner, K.; Greve, H.; Zaporojtchenko, V.; Faupel, F.

    2006-12-01

    Gold nanoclusters can be dispersed into the surface of a bisphenol-A polycarbonate film by acetone vapour induced crystallization, an effect which has been demonstrated in a previous publication of our group. Gold nanoclusters were deposited by physical vapour deposition on an amorphous thin film of polycarbonate. After vapour induced crystallization these clusters were detected by depth profiling to be embedded into the surface, with a concentration maximum in a depth of approximately 100 nm. In this work, we replaced the BPA by the modified tetramethyl bisphenol-A polycarbonate, which shows a slower crystallization kinetics. A strong enhancement of the dispersion depth has been achieved by thermal pre-embedding of the clusters into the surface. Surface analysis by means of atomic force microscopy reflects the rearrangement of polymer material in the course of crystallization.

  14. Excimer laser beam profile recording based on electrochemical etched polycarbonate

    International Nuclear Information System (INIS)

    Parvin, P.; Jaleh, B.; Zangeneh, H.R.; Zamanipour, Z.; Davoud-Abadi, Gh.R.

    2008-01-01

    There is no polymeric detector used to register the beam profile of UV lasers. Here, a method is proposed for the measurement of intensive UV beam pattern of the excimer lasers based on the photoablated polycarbonate detector after coherent UV exposure and the subsequent electrochemical etching. UV laser induced defects in the form of self-microstructuring on polycarbonate are developed to replicate the spatial intensity distribution as a beam profiler

  15. Fast relaxational motions in polycarbonate glass

    International Nuclear Information System (INIS)

    Saviot, L.; Duval, E.; Jal, J.F.; Dianoux, A.J.

    1999-01-01

    Complete text of publication follows. Inelastic neutron scattering from amorphous bis-phenol A polycarbonate was observed as a function of temperature from 15 K to 390 K (Tg = 420 K). The deduced mean square displacement and the vibrational density of states show that relaxational motions exist down to a temperature of 80 K. The relaxational scattering function, S(Q,t), can be described by two different regimes of relaxation: (1) a Debye-like process, with a characteristic time close to 1 ps, which is very weakly thermally activated; (2) a much slower process, which is thermally activated. The contribution of the fastest relaxation is related to the dynamical hole volume measured by positron annihilation lifetime spectroscopy, as already observed for the poly(methyl methacrylate) glass [1]. The dependence of the momentum transfer will be considered in order to obtain informations on the localization or diffusivity of the oberved different relaxations. This study of relaxation in a polymeric glass will be compared with a previous work [2]. (author)

  16. Stability of Atmospheric-Pressure Plasma Induced Changes on Polycarbonate Surfaces

    Science.gov (United States)

    Sharma, Rajesh; Holcomb, Edward; Trigwell, Steve

    2006-01-01

    Polycarbonate films are subjected to plasma treatment in a number of applications such as improving adhesion between polycarbonate and silicon alloy in protective and optical coatings. The changes in surface chemistry due to plasma treatment have tendency to revert back. Thus stability of the plasma induced changes on polymer surfaces over desired time period is very important. The objective of this study was to examine the effect of ageing on atmospheric pressure helium-plasma treated polycarbonate (PC) sample as a function of treatment time. The ageing effects were studied over a period of 10 days. The samples were plasma treated for 0.5, 2, 5 and 10 minutes. Contact angle measurements were made to study surface energy changes. Modification of surface chemical structure was examined using, X-ray Photoelectron Spectroscopy (XPS). Contact angle measurements on untreated and plasma treated surfaces were made immediately, 24, 48, 72 and 96 hrs after treatment. Contact angle decreased from 93 deg for untreated sample to 30 deg for sample plasma treated for 10 minutes. After 10 days the contact angles for the 10 minute plasma treated sample increased to 67 deg, but it never reverted back to that of untreated surface. Similarly the O/C ratio increased from 0.136 for untreated sample to 0.321 for 10 minute plasma treated sample indication increase in surface energy.

  17. Behavior of composite and polycarbonate plate under impact

    Directory of Open Access Journals (Sweden)

    Viot P.

    2010-06-01

    Full Text Available The use of filled composite materials in passive safety structure has significantly increased recently because of their low specific mass, stiffness and energy absorption capacities. However those new light weight materials are supposed to exhibit equal or higher performances than classical ones. Therefore interesting applications by using those materials can be thought about like in the manufacturing of aeronautical helmets. Constituted of an outer shell and an inner foam structure, helmet must protect pilots from an impact by absorbing energy as much as possible and avoid contact between head and impactor. Nowadays different standards describe the minimum required performance for shock attenuation and penetration resistance of helmets [1]. These standards are based on acceleration time history measurements recorded from an accelerometer located at the headform center of mass. For aeronautical standard, acceleration peak value is the only one parameter concerning shock attenuation. Its value must not exceed 300 g, where g = 9.81 m.s-2. Concerning penetration resistance, no contact can be accepted between the penetrating striker and the headform. The outer shell of the helmet has to resist penetration in order to absorb and to extend the input energy over the foam. The most important part of energy is dissipated by polymeric foam through collapse processes under impact [2]. Nevertheless a significant part of energy (one third [3, 4] can be dissipated by the plastic deformation of the shell and the occurrence of damage mechanisms. To obtain different dissipative phenomena, various materials were studied: a Three different kinds of polycarbonate were used. This type of material is well known for its large viscoplastic deformations without any significant hardening. In other words it is a very good candidate for helmet application because of high specific energy dissipation and a stress cut-off effect. Moreover a larger affected zone is expected

  18. An experimental study of the fabrication of polycarbonate optical waveguides

    Science.gov (United States)

    Chen, Jianguo; Zhang, Xiao-yang; Zhang, Tong; Zhu, Jing-song; Wu, Peng-qin; Zhou, Jing-lun; Fan, Jiang-feng; Yan, Hao-feng

    2008-12-01

    A novel polycarbonate (PC) was introduced to apply in the optical waveguide devices. PC has following distinct merits than common polycarbonate: good processability, high thermal stability up to 293 C° and high optical transparency. Optical properties of absorption behavior and propagation loss were investigated in slab waveguides, and low propagation losses of 0.335 dB/cm (@1550nm) and 0.197 dB/cm @632.8nm) have been achieved by using prismcoupler. Additionally, straight optical waveguide and MMI coupler of ring resonator were fabricated using ultraviolet (UV) cured resin Norland optical adhesive 61 (NOA61) as under or upper cladding layer and polycarbonate as waveguide core-layer material through conventional methods such as spin coating, photolithography and reactive ion etching (RIE). The process was studied in detail and the experimental results were given.

  19. A Polycarbonate/Magnesium Oxide Nanocomposite with High Flame Retardancy.

    Science.gov (United States)

    Dong, Quanxiao; Gao, Chong; Ding, Yanfen; Wang, Feng; Wen, Bin; Zhang, Shimin; Wang, Tongxin; Yang, Mingshu

    2012-01-15

    A new flame retardant polycarbonate/magnesium oxide (PC/MgO) nanocomposite, with high flame retardancy was developed by melt compounding. The effect of MgO to the flame retardancy, thermal property, and thermal degradation kinetics were investigated. Limited oxygen index (LOI) test revealed that a little amount of MgO (2 wt %) led to significant enhancement (LOI = 36.8) in flame retardancy. Thermogravimetric analysis results demonstrated that the onset temperature of degradation and temperature of maximum degradation rate decreased in both air and N 2 atmosphere. Apparent activation energy was estimated via Flynn-Wall-Ozawa method. Three steps in the thermal degradation kinetics were observed after incorporation of MgO into the matrix and the additive raised activation energies of the composite in the full range except the initial stage. It was interpreted that the flame retardancy of PC was influenced by MgO through the following two aspects: on the one hand, MgO catalyzed the thermal-oxidative degradation and accelerated a thermal protection/mass loss barrier at burning surface; on the other hand, the filler decreased activation energies in the initial step and improved thermal stability in the final period.

  20. Cellulose nanocrystals as organic nanofillers for transparent polycarbonate films

    Science.gov (United States)

    Xu, Weinan; Qin, Zongyi; Yu, Houyong; Liu, Yannan; Liu, Na; Zhou, Zhe; Chen, Long

    2013-04-01

    Cellulose nanocrystals (CNCs) produced by sulfuric acid hydrolysis as organic nanofillers were dispersed into polycarbonate (PC) in organic solution through a solvent exchange procedure, and their influence on the optical, mechanical, and thermal properties of the resulting composite films were studied. It is demonstrated that due to the good dispersion of the nanofillers in the polymeric matrix, the formation of strong hydrogen bonds between carbonyl groups of PC and hydroxyl groups of the CNCs can be achieved, leading to a simultaneous reinforcement effect on mechanical and thermal properties of the composite films. Moreover, it was further found that the existence of nanofillers in the composite efficiently hindered the main thermal degradation pathways of PC involving the chain scission at carbonate linkage and rearrangement of carbonate groups. Compared with neat PC, the composite film with 3 wt% CNCs has an increase of about 30.6 % in tensile strength, 27.3 % in Young's modulus, and 3.3 % in maximum decomposition temperature, but still remain quite transparent.

  1. THE AQUATIC-POLYCARBONATE SKYLIGHT FOR SURABAYA INDONESIA

    Directory of Open Access Journals (Sweden)

    Danny Santoso Mintorogo

    2007-01-01

    Full Text Available This paper will indicate of how appropriate use of aquatic skylight module installed on buildings in the tropical zone compared to the ones in the subtropical climate. In order for energy saving strategies, the aquatic-polycarbonate skylight system is used in the tropical climate. In the tropical hot humid climate, Indonesia has received huge amount of global direct and diffuse radiations on horizontal roofs throughout the year, approximately 525 watts per square meter of solar radiation will impact on flat roofs or skylights on a clear sunny day in Surabaya city. Ironically, most of the commercial and institution buildings are equipped with Western skylight styles in Surabaya without any modifications. The aquatic-polycarbonate skylight is the system that will control daylight, scatter direct solar heat radiation, cool the indoor polycarbonate surface temperature, and collect solar hot water at the same time. The concept of using the water as shading device has three goals: first of all, the flushing water in the polycarbonate holes tries to scatter horizontal or tiled skylight direct sun-ray radiation, and minimize the direct sun heat temperature on the polycarbonate with flushing water continuously. Secondly, the sparkle flushing water in series of square holes of polycarbonate will bounce and disperse the direct sunlight into the space below enhancing daylight patterns. Finally, while bouncing, sparkling and scattering direct sunlight, those series of flushing water holes would also collect the solar heat radiation as solar hot water. Each system could works nicely to absorb, to scatter, to minimize, and to obtain the solar heat radiation for solar hot water in buildings. This strategy aims to provide a clean environment living zones with applying passive heating and cooling systems.

  2. Power law creep of polycarbonate by Berkovich nanoindentation

    Science.gov (United States)

    Gao, Chenghui; Liu, Ming

    2017-10-01

    Power-law creep of polycarbonate was investigated by Berkovich indentation under three different conditions at room temperature, namely: constant displacement rate condition, constant displacement loading condition, and constant ratio of loading rate over load condition. Only the data during the loading process were analysed, and the experiments under different loading conditions gave consistent results that accorded well with theoretical prediction by dimensional analysis of indentation of power-law creep material. Material constants were characterized by curve fitting of the experimental results with theoretical equations, and the power law exponent for the power-law creep relation was found to be about 0.138 for the notably soft polycarbonate.

  3. Miscibility evolution of polycarbonate/polystyrene blends during compounding

    DEFF Research Database (Denmark)

    Chuai, Chengzhi; Almdal, Kristoffer; Johannsen, Ib

    2002-01-01

    The miscibility evolution of polycarbonate/polystyrene (PC/PS) blends during the compounding process in three blending methods of industrial relevance, namely melt blending, remelt blending in a twin-screw extruder and third melt blending in an injection molding machine, was investigated by measu......The miscibility evolution of polycarbonate/polystyrene (PC/PS) blends during the compounding process in three blending methods of industrial relevance, namely melt blending, remelt blending in a twin-screw extruder and third melt blending in an injection molding machine, was investigated...

  4. Polycarbonate-silsesquioxane and polycarbonate-siloxane nanocomposites: Synthesis, characterization, and application in the fabrication of porous inorganic films

    Science.gov (United States)

    Abdallah, Jassem

    Three types of poly(bicycle[2.2.1]heptane carbonate) or poly(norbornane carbonate) or PNC oligomers were synthesized and characterized via spectroscopic methods and elemental analyses to validate their chemical structures. End-group analyses were used to estimate the degree of polymerization of the oligomers via the use of proton nuclear magnetic resonance (1H NMR) results. Random-coil and rigid-rod models were used to estimate the sizes of individual PNC chains based on the degrees of polymerization calculated from NMR data. Due to the small sizes of the PNC chains, dynamic light scattering (DLS) was incapable of measuring the hydrodynamic radii, RH, of individual chains. Attempts at using gel permeation chromatography (GPC) data to estimate the hydrodynamic radii of individual chains consistently provided values that were an order of magnitude smaller than the estimated sizes of individual chains based on random-coil calculations. The thermal properties of PNCs were determined via differential scanning calorimetry (DSC) and thermogravimetric analyses (TGAs). All three types of PNC structures were both thermally-labile and acidolytically-labile, allowing them to be used as sacrificial materials in both direct-write and thermally-processed template systems. TGA data was used to determine the kinetic parameters for the thermolytic decomposition reactions and evolved-gas analysis via mass spectrometry (TGA-MS) was used to validate the mechanisms for polycarbonate thermolysis reactions that have been previously proposed in literature. PNC oligomers were freely-mixed with hydrogen silsesquioxane (HSQ) to form solutions that were spin-coated to form templated films. Ellipsometry and dielectric measurements were used to track the changes in the optical and dielectric properties of templated films and effective medium approximations were used to estimate the level of porosity incorporated within each porous film. Transmission electron microscopy (TEM) showed that the free

  5. Novel polycarbonate-based polyurethane elastomers: composition–property relationship

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Pavličevic, J.; Strachota, Adam; Poreba, Rafal; Bera, O.; Kaprálková, Ludmila; Baldrian, Josef; Šlouf, Miroslav; Lazić, N.; Budinski-Simendic, J.

    2011-01-01

    Roč. 47, č. 5 (2011), s. 959-972 ISSN 0014-3057 R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane elastomer * polycarbonate diol * montmorillonite Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.739, year: 2011

  6. Synthesis of copper nanoparticles in polycarbonate by ion ...

    Indian Academy of Sciences (India)

    Administrator

    2 with a beam current density of 800 nA/cm. 2 . The composites formed were structurally characterized using Ultraviolet-Visible (UV-Visible) absorption spectroscopy. The appearance of particle plasmon resonance peak, characteristic of copper nanoparticles at. 603 nm in absorption spectra of polycarbonate implanted to a ...

  7. Multifunctional transparent protective coatings on polycarbonates prepared using PECVD

    Czech Academy of Sciences Publication Activity Database

    Mocanu, V.; Stoica, A.; Kelar, L.; Franta, D.; Bursíková, V.; Mikšová, Romana; Peřina, Vratislav

    2012-01-01

    Roč. 106, SI5 (2012), s. 1460-1464 ISSN 0009-2770 Institutional support: RVO:61389005 Keywords : multilayered coatings * protective * transparent * polycarbonate Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.453, year: 2012

  8. Polycarbonates: a long-term highly sensitive radon monitor

    CERN Document Server

    Pressyanov, D; Poffijn, A; Meesen, G; Deynse, A V

    2000-01-01

    An approach for long-term (either retrospective or prospective) sup 2 sup 2 sup 2 Rn measurements is proposed that is based on the combination of the high radon absorption ability of some polycarbonates with their alpha track-etch properties. The detection limit is projected to be <10 Bq m sup - sup 3 for an exposure time of 20 yr.

  9. Modifications induced in the polycarbonate Makrofol KG polymer by ...

    Indian Academy of Sciences (India)

    Abstract. Swift heavy ions interact predominantly through inelastic scattering while traversing any polymer medium and produce excited/ionized atoms. Here samples of the polycarbonate Makrofol of approximate thickness 20 µm, spin coated on GaAs substrate were irradiated with 50 MeV Li ion (+3 charge state). Build-in ...

  10. Modifications induced in the polycarbonate Makrofol KG polymer by ...

    Indian Academy of Sciences (India)

    Swift heavy ions interact predominantly through inelastic scattering while traversing any polymer medium and produce excited/ionized atoms. Here samples of the polycarbonate Makrofol of approximate thickness 20 m, spin coated on GaAs substrate were irradiated with 50 MeV Li ion (+3 charge state). Build-in ...

  11. Characterization of a Sulfonated Polycarbonate Resistive Humidity Sensor

    Directory of Open Access Journals (Sweden)

    Claudio L. Donnici

    2013-02-01

    Full Text Available In this work; resistive moisture sensors were obtained by dip coating sulfonated polycarbonate (SPC onto silver interdigitated electrodes. Commercial polycarbonate was sulfonated with acetyl sulphate at two different sulfonation degrees corresponding to 9.0 and 18.0 mole %. Impedance spectroscopy was used to investigate the humidity sensing properties at controlled relative humidity (RH% environments generated from standard saline solutions in the range of 11–90 RH%. For the highest sulfonated sample; in the RH% range investigated (11 to 90%; the sensor impedance changed from 4.7 MΩ to 18 kΩ. Humidity sensors made from sulfonated polycarbonate showed exponential decay behavior of the impedance at constant frequency with the environmental relative humidity. Sample 9SPC presented dielectric relaxation response for environmental humidity between 58 and 90 RH% while sample 18SPC presented dielectric relaxation response for the entire measured range between 11 and 90 RH%. Sulfonated polycarbonate could be a promising material for the fabrication of simple and cheap humidity-sensing sensors for the assessment of relative humidity of the surrounding environment, as suggested by experimental results.

  12. Properties of polycarbonate containing BaTiO3 nanoparticles

    Science.gov (United States)

    Lomax, J. F.; Fontanella, J. J.; Edmondson, C. A.; Wintersgill, M. C.; Wolak, M. A.; Westgate, M. A.; Lomax, E. A.; Lomax, P. Q.; Bogle, X.; Rúa, A.; Greenbaum, S. G.

    2014-03-01

    The real part of the relative permittivity, ɛ', and dielectric loss, tan δ, have been determined at audio frequencies at temperatures from about 5 K to 350 K for nano-composites composed of BaTiO3 nanoparticles and polycarbonate. The room temperature breakdown strength was also measured and thermal analysis, nuclear magnetic resonance and scanning electron microscopy studies were carried out. For some films the nanoparticles were surface-treated (STNP) while for others they were not (UNP). For concentrations of UNP greater than about 3.4 vol. %, ɛ' is much larger than expected on the basis of laws of mixing. On the other hand, ɛ' for materials made using STNP is well-behaved. Correspondingly, increased loss (ɛ″ or tan δ) in the vicinity of room temperature is observed for the materials made from UNP. The anomalously large values of relative permittivity and increased loss are attributed to the presence of large aggregates in the materials made using the UNP. For both UNP-and STNP-based materials, the breakdown strength is found to decrease as nanoparticle concentration increases. The breakdown strength for the materials made using STNP is found to be larger for all concentrations than for those containing UNP despite the presence of large aggregates in some of the STNP-based materials. This shows that breakdown is strongly affected by the nanoparticle surfaces and/or the interface layer. It is also found that the breakdown strength for materials made using UNP increases as particle size increases. Finally, variable temperature and pressure proton nuclear magnetic resonance relaxation measurements were made to assess the effect of nanoparticle inclusion on polymer motion, and the effects were found to be very minor.

  13. The impact of chlorhexidine mouth rinse on the bond strength of polycarbonate orthodontic brackets.

    Science.gov (United States)

    Hussein, Farouk Ahmed; Hashem, Mohammed Ibrahim; Chalisserry, Elna P; Anil, Sukumaran

    2014-11-01

    The purpose of the current in-vivo study was to assess the effect of using 0.12% chlorhexidine (CHX) mouth rinse, before bonding, on shear bond strength of polycarbonate brackets bonded with composite adhesive. Eighteen orthodontic patients with a mean age 21.41 ± 1.2 years, who were scheduled to have 2 or more first premolars extracted, were included in this study. Patients were referred for an oral prophylaxis program which included, in part, the use of a mouth rinse. Patients were divided into 2 groups, a test group of 9 patients who used 0.12% CHX gluconate mouth rinse twice daily and a control group of 9 patients who used a mouth rinse without CHX, but with same color. After 1 week, polycarbonate brackets were bonded to first premolars with Transbond XT composite adhesive. Premolars were extracted after 28 days and tested for shear bond strength on a universal testing machine. Student's t-test was used to compare shear bond strengths of both groups. No statistically significant difference was found in bond strengths' values between both groups. The test group (with CHX) has mean shear bond strength of 14.21 ± 2.42 MPa whereas the control group (without CHX) revealed a mean strength of 14.52 ± 2.31 MPa. The use of 0.12% CHX mouth rinse, for one week before bonding, did not affect the shear bond strength of polycarbonate brackets bonded with Transbond composite. Furthermore, these brackets showed clinically acceptable bond strength.

  14. Domain Structures in Nematic Liquid Crystals on a Polycarbonate Surface

    Directory of Open Access Journals (Sweden)

    Vasily F. Shabanov

    2013-08-01

    Full Text Available Alignment of nematic liquid crystals on polycarbonate films obtained with the use of solvents with different solvations is studied. Domain structures occurring during the growth on the polymer surface against the background of the initial thread-like or schlieren texture are demonstrated. It is established by optical methods that the domains are stable formations visualizing the polymer surface structures. In nematic droplets, the temperature-induced transition from the domain structure with two extinction bands to the structure with four bands is observed. This transition is shown to be caused by reorientation of the nematic director in the liquid crystal volume from the planar alignment to the homeotropic state with the pronounced radial configuration of nematic molecules on the surface. The observed textures are compared with different combinations of the volume LC orientations and the radial distribution of the director field and the disclination lines at the polycarbonate surface.

  15. Monitoring detachment and diffusion of metallic species in polycarbonate

    Science.gov (United States)

    Bencomo, M.; Castro-Colín, M.; López, J. A.; Ramírez-Homs, E.

    2013-07-01

    Photon absorption is known to create peroxy radicals in polymers, in a process that entails the removal of hydrogen atoms and the subsequent breakage of bonds. Bond-breaking is found to free, from the polymeric matrix, metallic additives which are then able to diffuse out, as evidenced by the change in both the metallic fluorescence yield and the XPS profiles of C, N, and O. Polycarbonate was artificially weathered using UV radiation from mercury emission lines at 365, 405 and 435 nm, followed by thermal treatment. The UV wavelengths used have energies comparable to those of covalent bonds found in polymeric chains. Both processes, light exposure and thermal, have the purpose of stimulating the degradation of polycarbonate.

  16. Migration of 2-butoxyethyl acetate from polycarbonate infant feeding bottles

    DEFF Research Database (Denmark)

    Petersen, Jens Højslev; Lund, K.H.

    2003-01-01

    An enforcement campaign was carried out to assess the migration of 2-butoxyethyl acetate (2-BEA) from polycarbonate infant feeding bottles intended for repeated use. Migration was measured by three successive migration tests into two of the European Union official food simulants: distilled water...... and 3% acetic acid testing at 40degrees C for 10 days. The Danish Veterinary and Food Administration (DVFA) has assessed that a migration above 0.33 mg for 2-BEA and a group of eight related substances kg(-1) foodstuff from plastics articles used exclusively for infants is unacceptable. Migration of 2......-BEA was found from eight of 12 bottles. However, migration above the target value of 0.33 mg kg(-1) was not observed in the third decisive test from any of the 12 different brands of polycarbonate feeding bottles. A migration of between 0.05 and 0.26 mg kg(-1) from seven of 12 bottles was measured...

  17. Water heating solar system using collector with polycarbonate absorber surface

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Luiz Guilherme Meira de; Sodre, Dilton; Cavalcanti, Eduardo Jose Cidade; Souza, Luiz Guilherme Vieira Meira de; Mendes, Jose Ubiragi de Lima [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)], e-mails: lguilherme@dem.ufrn.br, diltonsodre@ifba.edu.br, ubiragi@ct.ufrn.br

    2010-07-01

    It is presented s solar collector to be used in a heating water for bath system, whose main characteristics are low cost and easy fabrication and assembly processes. The collector absorber surface consists of a polycarbonate plate with an area of 1.5 m{sup 2}. The water inlet and outlet are made of PVC 50mm, and were coupled to a 6mm thick polycarbonate plate using fiberglass resin. A 200 liters thermal reservoir will be used. This reservoir is also alternative. The absorber heating system works under thermo-siphon regimen. Thermal parameters will be evaluated to prove the feasibility of the studied solar heating system to obtain bath water for a four people family. (author)

  18. Phase separation and orientation in EVA/polycarbonate

    International Nuclear Information System (INIS)

    Martins-Franchetti, S.M.; Nunes, S.P.

    1988-01-01

    Blends of the polycarbonate of bisphenol-A-(PC) with poly(ethylene-co-vinylacetate) (EVA) were prepared by solution casting in different solvents and various proportions. Their behaviours was examined by diferential scanning calorimetry (DSC), X-ray diffraction and u.v. spectrophotometry. The results obtained show that PC and EVA form partially miscible blends. In some cases, birefringence was observed by optical microscopy indicating the occurrence of polymer orientation in the neighbourhood of the interfaces. (author) [pt

  19. Use of polycarbonate plastic products and human health

    OpenAIRE

    R. K. Srivastava; Sushila Godara

    2013-01-01

    As plastic and plastic products are being used in day to day at the cost of environment pollution, the human and wild life health and has become a global concern. Researchers found link between abnormal liver enzymes in the people and Bisphenol-A (BPA). Changes in insulin resistance, reproduction system, cardiovascular and brain function are also reported. BPA is used in the production of epoxy resins, polycarbonate resins, and polyester resins. BPA can leach out of certain plastic products i...

  20. Modification of Low Refractive Index Polycarbonate for High Refractive Index Applications

    Directory of Open Access Journals (Sweden)

    Gunjan Suri

    2009-01-01

    Full Text Available Polycarbonates and polythiourethanes are the most popular materials in use today, for optical applications. Polycarbonates are of two types which fall in the category of low refractive index and medium refractive index. The present paper describes the conversion of low refractive index polycarbonates into high refractive index material by the use of a high refractive index monomer, polythiol, as an additive. Novel polycarbonates, where the properties of refractive index and Abbe number can be tailor made, have been obtained. Thermal studies and refractive index determination indicate the formation of a new polymer with improved properties and suitable for optical applications.

  1. UV Induced Degradation of Polycarbonate-Based Lens Materials and Implications for the Heath Care Field

    Science.gov (United States)

    Harkay, J. R.; Henry, Jerry

    2006-10-01

    Experimental research is being carried out at Keene State at the undergraduate level that utilizes facilities in both physics and chemistry to study the effects of mono- and polychromatic UV radiation from various sources, including a Deuterium lamp, a solarization unit (at Polyonics, a local industry), and the Sun, to study the photodegradation of polycarbonate-based lens materials used to produce eyewear. Literature in the field of optometry and ophthalmology indicates a correlation between exposure to the UVB band of natural sunlight and the onset of cataract formation, as well as other eye disorders. The public is usually advised that plastic eyeglass lenses will provide protection from this damaging radiation. It is well known that polycarbonate plastic ``yellows'' when exposed to intense sunlight and, particularly, UV light^1,2, either via photo-Fries rearrangement or by a photooxidative process, forming polyconjugated systems and is an industrial concern primarily for cosmetic reasons. We have preliminary data, however, that indicates that the yellowing'' is an indication of a more sinister problem in the case of eyeglasses in that it is accompanied by an increase in transmissivity in the UVB band where the wearer expects and needs protection. Our group includes a local optometrist who will share results with peers in his field. [1] A. Andrady, J. Polymer Sci., 42, 1991 [2] E. P. Gorelov, Inst. Khim. Fiz., Russian Federation

  2. UV Induced Degradation of Polycarbonate-Based Lens Materials and Implications for the Heath Care Field

    Science.gov (United States)

    Harkay, J. Russell; Henry, Jerry

    2007-04-01

    Experimental undergraduate research at Keene State College has utilized facilities in physics and chemistry and at Polyonics, a local firm to study the effects of mono- and polychromatic UV radiation from various sources, including a Deuterium lamp, a solarization unit, a monochromator, and natural sunlight to study the photodegradation of polycarbonate-based lens materials used to produce eyewear using spectrophotometry and FTIR analysis. Ophthalmologic literature indicates a correlation between exposure to the UVB band of sunlight and the onset of cataract formation and macular degeneration. It is well known that polycarbonate plastic ``yellows'' when exposed to intense sunlight and, particularly, UV light either via photo-Fries rearrangement or by a photo oxidative process, forming polyconjugated systems and is a concern primarily for cosmetic reasons. Our data indicates that the ``yellowing'' is an indication of a more sinister problem in the case of eyeglasses in that spectrophotometric comparison shows it is accompanied by an increase in transmissivity in the UVB band where the wearer expects and needs protection. FTIR results indicate a degradation of molecular stabilizers and the appearance of free radicals that indicate a breakdown of the resin's chemical structure. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.NES07.B1.4

  3. Directed Hierarchical Patterning of Polycarbonate Bisphenol A Glass Surface along Predictable Sites

    Directory of Open Access Journals (Sweden)

    Mazen Khaled

    2015-01-01

    Full Text Available This paper reports a new approach in designing textured and hierarchical surfaces on polycarbonate bisphenol A type glass to improve hydrophobicity and dust repellent application for solar panels. Solvent- and vapor-induced crystallization of thermoplastic glass polycarbonate bisphenol A (PC is carried out to create hierarchically structured surfaces. In this approach dichloromethane (DCM and acetone are used in sequence. Samples are initially immersed in DCM liquid to generate nanopores, followed by exposing to acetone vapor resulting in the generation of hierarchical structure along the interporous sites. The effects of exposure time on the size, density, and distance of the generated spherules and gaps are studied and correlated with the optical transmittance and contact angle measurements at the surface. At optimized exposure time a contact angle of 98° was achieved with 80% optical transmittance. To further increase the hydrophobicity while maintaining optical properties, the hierarchical surfaces were coated with a transparent composite of tetraethyl orthosilicate as precursor and hexamethyldisilazane as silylation agent resulting in an average contact angle of 135.8° and transmittance of around 70%. FTIR and AFM characterization techniques are employed to study the composition and morphology of the generated surfaces.

  4. THERMAL properties and morphology of Polypropylene/Polycarbonate/Polypropylene-Graft-Maleic anhydride blends

    Directory of Open Access Journals (Sweden)

    Mat-Shayuti M. S.

    2016-01-01

    Full Text Available This work investigates the effect of blending polycarbonate (PC into polypropylene (PP matrix polymer on thermal properties and morphology. The blends, containing 5% to 35% of polycarbonate and 5% compatibilizer, were compounded using twin-screw extruder and fabricated into standard tests samples using injection or compression molding. The compatibilizer used was polypropylene-graft-maleic anhydride (PP-g-MA. Thermogravimetric analysis (TGA showed improved thermal degradation temperature of PP/PC/PP-g-MA blends compared to pure PP. As PC content increased, the thermal degradation temperature also improved. The highest improvement of thermal degradation temperature was 23.3%, demonstrated by 60/35/5 composition. It was found that the thermal stability of PP/PC blends was improved with the addition of PP-g-MA. PP-g-MA was suspected to enhance the phase adhesion between PP and PC, thus improving thermal stability. Microscopy analysis showed PC reinforcement phase existed as particulates dispersed in PP matrix phase. PC also was in irregular shapes of fibers or flakes in certain compositions, depending on PC fraction and compatibilizer content.

  5. Standard specification for architectural flat glass clad polycarbonate

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This specification covers the quality requirements for cut sizes of glass clad polycarbonate (GCP) for use in buildings as security, detention, hurricane/cyclic wind-resistant, and blast and ballistic-resistant glazing applications. 1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  6. Influence of asymmetric etching on ion track shapes in polycarbonate

    International Nuclear Information System (INIS)

    Clochard, M.-C.; Wade, T.L.; Wegrowe, J.-E.; Balanzat, E.

    2007-01-01

    By combining low-energy ion irradiation with asymmetric etching, conical nanopores of controlled geometry can be etched in polycarbonate (PC). Cone bases vary from 0.5 to 1 μm. Top diameters down to 17 nm are reached. When etching from one side, the pH on the other side (bathed in neutral or acidic buffer) was monitored. Etching temperature ranged from 65 deg. C to 80 deg. C. Pore shape characterization was achieved by electro replication combined with SEM observation. The tip shape depended on whether an acidic buffer was used or not on the stopped side

  7. Short-range order in blends of polycarbonates with polystyrenes

    Science.gov (United States)

    Arrighi, Valeria; Zajac, Wojciech; Shenoy, Suresh; Martin y Marero, David; Gabrys, Barbara J.; T. Garay, Maria; Gagliardi, Simona; Andersen, Ken H.

    2000-03-01

    The local structure of a series of blends of bisphenol-A polycarbonate (BPA-PC) and tetramethyl BPA-PC (TMPC) with various styrene-based polymers (poly(para-chlorostyrene), polystyrene, poly(meta-chlorostyrene) and poly(ortho-chlorostyrene)) has been investigated. Measurements on the D7 diffractometer at ILL were carried out at room temperature. We show that while the amorphous halo of TMPC is only slightly perturbed by blending, major differences are observed in all BPA-PC blends. We conclude that inter-chain correlations in BPA-PC blends are considerably altered compared to the pure component.

  8. Migration of bisphenol A into water from polycarbonate baby bottles during microwave heating

    NARCIS (Netherlands)

    Ehlert, K.A.; Beumer, C.W.E.; Groot, M.C.E.

    2008-01-01

    A comprehensive migration database was established for bisphenol A from polycarbonate baby bottles into water during exposure to microwave heating. Eighteen different brands of polycarbonate baby bottles sold in Europe were collected. Initial residual content of bisphenol A and migration after

  9. Cobalt Nanoparticle Inks for Printed High Frequency Applications on Polycarbonate

    Science.gov (United States)

    Nelo, Mikko; Myllymäki, Sami; Juuti, Jari; Uusimäki, Antti; Jantunen, Heli

    2015-12-01

    In this work the high frequency properties of low curing temperature cobalt nanoparticle inks printed on polycarbonate substrates were investigated. The inks consisted of 30-70 vol.% metallic cobalt nanoparticles and poly (methylene methacrylate) polymer, having excellent adhesion on polycarbonate and a curing temperature of 110°C. The influence of binder material content on the electromagnetic properties of the ink was investigated using the shorted microstrip transmission-line perturbation method. Changes in mechanical properties were evaluated with adhesion tests using the pull-out strength test and the ASTM D 3359-B cross-hatch tape peel test. The microstructure of the printed patterns was investigated with field emission scanning electron microscopy (FESEM). The inks remained mechanically durable with metal contents up to 60 vol.%, achieving pull-off strength of up to 5.2 MPa and the highest marks in adhesion of the tape peel test. The inks obtained a relative permeability of 1.5-3 in the 45 MHz-10 GHz band with a magnetic loss tangent of 0.01-0.06. The developed inks can be utilized in various printed electronics applications such as antenna miniaturization, antenna substrates and magnetic sensors or sensing.

  10. Shock response and spall behavior of polycarbonate and polymethyl methacrylate

    Science.gov (United States)

    Kawai, Nobuaki; Seki, Takuya; Mashimo, Tsutomu

    2017-06-01

    Polycarbonate and polymethyl methacrylate (PMMA) are major transparent polymer materials used in a wide range of applications. It is well known that these polymers show the strain-rate-dependence of mechanical properties. However, the mechanical behavior under the deformation with very high rates such as shock compression is still not well understood. In this study, plate-impact experiments were conducted on polycarbonate and PMMA to investigate their shock response and dynamic tensile (spall) behavior. The stress wave profiles propagated into samples were measured using PVDF piezoelectric film stress gauges embedded in samples. The spall strengths were determined by measuring free-surface-velocity profiles by means of the VISAR. Both measurements were performed simultaneously. The obtained stress-wave and free-surface profiles show that structural relaxation occur under shock-compressed state in both materials, but the tendencies of the relaxation in stress-strain plane are different each other even though they are typical amorphous polymer. In contrast, the spall strengths of both materials show same behavior that they are substantially constant under the shock loading up to about 2 GPa but decrease in the case of the shock loading above it.

  11. Interdiffusion of Polycarbonate in Fused Deposition Modeling Welds

    Science.gov (United States)

    Seppala, Jonathan; Forster, Aaron; Satija, Sushil; Jones, Ronald; Migler, Kalman

    2015-03-01

    Fused deposition modeling (FDM), a now common and inexpensive additive manufacturing method, produces 3D objects by extruding molten polymer layer-by-layer. Compared to traditional polymer processing methods (injection, vacuum, and blow molding), FDM parts have inferior mechanical properties, surface finish, and dimensional stability. From a polymer processing point of view the polymer-polymer weld between each layer limits the mechanical strength of the final part. Unlike traditional processing methods, where the polymer is uniformly melted and entangled, FDM welds are typically weaker due to the short time available for polymer interdiffusion and entanglement. To emulate the FDM process thin film bilayers of polycarbonate/d-polycarbonate were annealed using scaled times and temperatures accessible in FDM. Shift factors from Time-Temperature Superposition, measured by small amplitude oscillatory shear, were used to calculate reasonable annealing times (min) at temperatures below the actual extrusion temperature. The extent of interdiffusion was then measured using neutron reflectivity. Analogous specimens were prepared to characterize the mechanical properties. FDM build parameters were then related to interdiffusion between welded layers and mechanical properties. Understating the relationship between build parameters, interdiffusion, and mechanical strength will allow FDM users to print stronger parts in an intelligent manner rather than using trial-and-error and build parameter lock-in.

  12. Rheology, Morphology and Temperature Dependency of Nanotube Networks in Polycarbonate/Multiwalled Carbon Nanotube Composites

    International Nuclear Information System (INIS)

    Abbasi, Samaneh; Carreau, Pierre J.; Derdouri, Abdessalem

    2008-01-01

    We present several issues related to the state of dispersion and rheological behavior of polycarbonate/multiwalled carbon nanotube (MWCNT) composites. The composites were prepared by diluting a commercial masterbatch containing 15 wt% nanotubes using optimized melt-mixing conditions. The state of dispersion was then analyzed by scanning and transmission electron microscopy (SEM, TEM). Rheological characterization was also used to assess the final morphology. Further, it was found that the rheological percolation threshold decreased significantly with increasing temperature and finally reached a constant value. This is described in terms of the Brownian motion, which increases with temperature. However, by increasing the nanotube content, the temperature effects on the complex viscosity at low frequency decreased significantly. Finally, the percolation thresholds were found to be approximately equal to 0.3 and 2 wt% for rheological and electrical conductivity measurements, respectively

  13. Magnetoelectrolysis of Co nanowire arrays grown in a track-etched polycarbonate membrane

    International Nuclear Information System (INIS)

    Sanchez-Barriga, J.; Lucas, M.; Rivero, G.; Marin, P.; Hernando, A.

    2007-01-01

    Arrays of Cobalt nanowires with a controlled length of 6μm have been fabricated by electrochemical deposition into the pores of track-etched polycarbonate membranes with a nominal pore diameter of 30nm. The magnetic properties of Co-deposited nanowires and the effects of a magnetic field applied during electrodeposition of the arrays have been studied. An enhancement of the mass deposition rate due to the presence of a 50Oe magnetic field along the nanowire axis has been observed by measuring the experimental development of the current in the electrochemical cell during the fabrication process. X-ray diffraction measurements reveal a different polycrystalline degree for each deposition configuration, indicating that the crystalline structure of the deposited material has been substantially modified. Magnetic measurements show a clear dependence of the anisotropy directions on the orientation of the magnetic field applied during the electrodeposition

  14. Chlorinated tyrosine derivatives in insect cuticle

    DEFF Research Database (Denmark)

    Andersen, Svend Olav

    2004-01-01

    , not-yet sclerotized cuticle of adult femur and tibia, the amounts increased rapidly during the first 24 h after ecdysis and more slowly during the next two weeks. Control analyses using stable isotope dilution mass spectrometry have confirmed that the chlorinated tyrosines are not artifacts formed...

  15. Thrombogenicity tests on ar-irradiated polycarbonate foils

    International Nuclear Information System (INIS)

    Trindade, Gustavo F.; Rizzutto, Marcia A.; Silva, Tiago F.; Moro, Marcos V.; Added, Nemitala; Tabacniks, Manfredo H.; Cunha, Tatiana F.; Higa, Olga Z.

    2013-01-01

    Understanding polymer surface properties is extremely important for the most wide range of their applications, from basic coating to the most complex composites and biomaterials. Low energy ion beam irradiation of polymer can improve such surface properties. By modifying its surface biocompatibility, polymers are excellent candidates for biomaterials, due to its malleability and low weight, when compared to metals. In this work, we irradiated 30-μm Bisphenol-A Polycarbonate foils with 23-keV Argon ion beam at six different doses. Aluminium foils were simultaneously irradiated in order to measure the doses by Rutherford Backscattering Spectroscopy. The surface modifications after the argon ion beam irradiation were analyzed by water contact angle measurements and atomic force microscopy. Platelet adhesion tests were used in order to investigate thrombogenicity, showing a growing tendency with the irradiated Argon dose. (author)

  16. Morphology Evolution of Polycarbonate-Polystyrene Blends During Compounding

    DEFF Research Database (Denmark)

    Chuai, Chengzhi; Almdal, Kristoffer; Johannsen, Ib

    2001-01-01

    The morphology evolution of polycarbonate-polystyrene (PC/PS) blends during the compounding process in three blending methods of industrial relevance, namely melt blending, re-melt blending in a twin-screw extruder and tri-melt blending in an injection-moulding machine, was investigated using...... scanning electron microscopy (SEM) Co examine nine blend compositions. Blends were prepared at compositions where phase inversion was expected to occur according to model predictions. The experimental results were compared to the values of the point of phase inversion calculated with the semi......-empirical model. The results show that the formation of co-continuous morphology strongly depends on blend composition and melt blending method, whereas the model prediction for phase inversion deviates from the experimental values. Further, we found that the initial mechanism of morphology evolution involves...

  17. Graphene Oxide Reinforced Polycarbonate Nanocomposite Films with Antibacterial Properties

    Directory of Open Access Journals (Sweden)

    R. Mahendran

    2016-01-01

    Full Text Available The incorporation of carbonaceous nanofillers into polymers can result in significant materials with improved physicochemical properties and novel composite functionalities. In this study, we have fabricated antibacterial, lightweight, transparent, and flexible graphene oxide (GO reinforced polycarbonate thin films by a facile and low-cost methodology. Solution blending is employed to get a homogeneous mixture of PC-GO composites at various loading of GO, and the thin films are prepared by dry-wet phase inversion technique. Thermal studies and micrographs of the films revealed the incorporation of GO in PC matrix. Microstructure of the thin films showed the homogeneous dispersion of GO at micro- and nanoscales; however, at higher loading of GO (0.7%, significant agglomeration is observed. More importantly, PC-GO composite films exhibited excellent antibacterial activities against E. coli and S. aureus, owing to the antibacterial nature of GO nanoparticles.

  18. Thrombogenicity tests on ar-irradiated polycarbonate foils

    Energy Technology Data Exchange (ETDEWEB)

    Trindade, Gustavo F.; Rizzutto, Marcia A.; Silva, Tiago F.; Moro, Marcos V.; Added, Nemitala; Tabacniks, Manfredo H., E-mail: g.ferraz@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. de Fisica; Delgado, Adriana O. [Universidade Federal de Sao Carlos (UFSCAR), Sorocaba, SP (Brazil); Cunha, Tatiana F. [Biosintesis P and D do Brasil, Sao Paulo, SP (Brazil); Higa, Olga Z. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Biotecnologia

    2013-07-01

    Understanding polymer surface properties is extremely important for the most wide range of their applications, from basic coating to the most complex composites and biomaterials. Low energy ion beam irradiation of polymer can improve such surface properties. By modifying its surface biocompatibility, polymers are excellent candidates for biomaterials, due to its malleability and low weight, when compared to metals. In this work, we irradiated 30-μm Bisphenol-A Polycarbonate foils with 23-keV Argon ion beam at six different doses. Aluminium foils were simultaneously irradiated in order to measure the doses by Rutherford Backscattering Spectroscopy. The surface modifications after the argon ion beam irradiation were analyzed by water contact angle measurements and atomic force microscopy. Platelet adhesion tests were used in order to investigate thrombogenicity, showing a growing tendency with the irradiated Argon dose. (author)

  19. Novel polycarbonate-graphene nanocomposite foams prepared by CO2 dissolution

    OpenAIRE

    Gedler, Gabriel; Antunes, Marcelo de Sousa Pais; Redondo Realinho, Vera Cristina de; Velasco Perero, José Ignacio

    2012-01-01

    Originally published as "IOP Conference Series: Materials Science and Engineering", vol. 31, no 1, 2012. DOI:10.1088/1757-899X/31/1/012008. . Polycarbonate foams reinforced with 0,5 wt% of graphene were obtained by firstly melt-mixing the polycarbonate and graphene in an internal mixer, compression-moulding the melt-compounded grinded material and lastly dissolving CO2 inside a high pressure vessel. The CO2 desorption behaviour in the unfilled polycarbonate and nanocomposite was studied in...

  20. Polycarbonates from the polyhydroxy natural product quinic acid.

    Science.gov (United States)

    Besset, Céline J; Lonnecker, Alexander T; Streff, Jennifer M; Wooley, Karen L

    2011-07-11

    Strategies for the preparation of polycarbonates, derived from natural polyhydroxy monomeric repeat units, were developed for biosourced polycarbonates based on quinic acid. The design and synthesis of regioselectively tert-butyldimethylsilyloxy (TBS)-protected 1,4- and 1,5-diol monomers of quinic acid were followed by optimization of their copolymerizations with phosgene, generated in situ from trichloromethyl chloroformate, to yield protected poly(1,4-quinic acid carbonate) and poly(1,5-quinic acid carbonate). The molecular weights reached ca. 7.6 kDa, corresponding to degrees of polymerization of ca. 24, with polydispersities ranging from 2.0 to 3.5, as measured by SEC using tetrahydrofuran as the eluent and with polystyrene calibration standards. Partially because of the presence of the bicyclic backbone, each regioisomeric poly(quinic acid carbonate) exhibited relatively high glass-transition temperatures, 209 °C for poly(1,4-quinic acid carbonate) and 229 °C for poly(1,5-quinic acid carbonate). Removal of the TBS-protecting groups was studied under mild conditions to achieve control over potential competing reactions involving polymer degradation, which could include cleavage of lactones within the repeat units, carbonate linkages, or both between the repeat units. Full deprotection was not achieved without some degree of polymer degradation. The regiochemistry of the monomer showed significant impact on the reactivity during deprotection and also on the thermal properties, with the 1,5-regioisomeric polymer having lower reactivity and giving higher T(g) values, in comparison with the 1,4-regioisomer. Each regioisomer underwent a 10-20 °C increase in T(g) upon partial removal of the TBS-protecting groups. As the extent of deprotection increased, the solubility decreased. Ultimately, at long deprotection reaction times, the solubility increased and the T(g) decreased because of significant degradation of the polymers.

  1. Storage stability of bevacizumab in polycarbonate and polypropylene syringes

    Science.gov (United States)

    Khalili, H; Sharma, G; Froome, A; Khaw, P T; Brocchini, S

    2015-01-01

    Purpose To compare and examine the storage stability of compounded bevacizumab in polycarbonate (PC) and polypropylene (PP) syringes over a 6-month period. PC syringes have been used in a recent clinical study and bevacizumab stability has not been reported for this type of syringe. Methods Repackaged bevacizumab was obtained from Moorfields Pharmaceuticals in PC and PP syringes. Bevacizumab from the stored syringes was analysed at monthly time points for a 6-month period and compared with bevacizumab from a freshly opened vial at each time point. SDS-PAGE electrophoresis and size-exclusion chromatography (SEC) was used to observe aggregation and degradation. Dynamic light scattering (DLS) provided information about the hydrodynamic size and particle size distribution of bevacizumab in solution. VEGF binding and the active concentration of bevacizumab was determined by surface plasmon resonance (SPR) using Biacore. Results SDS-PAGE and SEC analysis did not show any changes in the presence of higher molecular weight species (HMWS) or degradation products in PC and PP syringes from T0 to T6 compared with bevacizumab sampled from a freshly opened vial. The hydrodynamic diameter of bevacizumab in the PC syringe after 6 months of storage was not significantly different to bevacizumab taken from a freshly opened vial. Using SPR, the VEGF binding activity of bevacizumab in the PC syringe was comparable to bevacizumab taken from a freshly opened vial. Conclusion No significant difference over a 6-month period was observed in the quality of bevacizumab repackaged into prefilled polycarbonate and polypropylene syringes when compared with bevacizumab that is supplied from the vial. PMID:25853399

  2. Estimation of Water Diffusion Coefficient into Polycarbonate at Different Temperatures Using Numerical Simulation

    DEFF Research Database (Denmark)

    Shojaee Nasirabadi, Parizad; Jabbaribehnam, Mirmasoud; Hattel, Jesper Henri

    2016-01-01

    Nowadays, many electronic systems are exposed to harsh conditions of relative humidity and temperature. Masstransport properties of electronic packaging materials are needed in order to investigate the influence of moisture andtemperature on reliability of electronic devices. Polycarbonate (PC...

  3. The influence of hard segment content on mechanical and thermal properties of polycarbonate-based polyurethane materials

    Directory of Open Access Journals (Sweden)

    Budinski-Simendić Jaroslava

    2012-01-01

    Full Text Available Aliphatic segmented polyurethanes were prepared by one-step procedure in catalytic reaction between polycarbonate diol, hexamethylene-diisocyanate and 1,4-butandiol (as chain extender. The hard segment content TS was varied (17, 24, 30 and 42 wt. % by changing the ratio of starting compounds. The soft segment is made from flexible aliphatic polycarbonate diol, while hard segments consist of chain extender and diisocyanate component. In order to study the hydrogen bonding formation and phase separation, Fourier transform infrared spectroscopy (FT-IR was used. Wide angle X-ray scattering (WAXS was performed to determine a degree of crystallinity and to investigate the phase behavior of prepared elastomers. The effect of TS content on mechanical properties (tensile strength, elongation at break and hardness was tested. Thermal behavior of prepared novel polycarbonate-based polyurethanes was investigated using differential scanning callorimetry (DSC. It was determined that the elastomer which contains the highest amount of urethane groups in its structure (TS content of 42 wt. % exhibits the most pronounced phase separation and the highest degree of crystallinity. All prepared polyurethanes exhibit high elongation at break (over 700%. The glass transition temperature Tg of prepared samples was in the temperature region from −39 to −36°C, and it was found to be slightly influenced by the soft segment content. The enthalpy of chain segments relaxation in diffused region between hard and soft domains (detected in the temperature range from 35 to 55 °C was decreased with the increase of hard segment content. The multiple melting of hard segments (connected with the dissruption of physical crosslinks appeared above 100 °C. It was found that the melting enthalpy linearly increases with the increase of urethane group content. Sample with 42 wt. % of TS has the highest value of melting enthalpy (41.5 J/g.

  4. Bisphenol A is released from used polycarbonate animal cages into water at room temperature

    Science.gov (United States)

    Howdeshell, Kembra L.; Peterman, Paul H.; Judy, Barbara M.; Taylor, Julia A.; Orazio, Carl E.; Ruhlen, Rachel L.; vom Saal, Frederick S.; Welshons, Wade V.

    2003-01-01

    Bisphenol A (BPA) is a monomer with estrogenic activity that is used in the production of food packaging, dental sealants, polycarbonate plastic, and many other products. The monomer has previously been reported to hydrolyze and leach from these products under high heat and alkaline conditions, and the amount of leaching increases as a function of use. We examined whether new and used polycarbonate animal cages passively release bioactive levels of BPA into water at room temperature and neutral pH. Purified water was incubated at room temperature in new polycarbonate and polysulfone cages and used (discolored) polycarbonate cages, as well as control (glass and used polypropylene) containers. The resulting water samples were characterized with gas chromatography/mass spectrometry (GC/MS) and tested for estrogenic activity using an MCF-7 human breast cancer cell proliferation assay. Significant estrogenic activity, identifiable as BPA by GC/MS (up to 310 micro g/L), was released from used polycarbonate animal cages. Detectable levels of BPA were released from new polycarbonate cages (up to 0.3 micro g/L) as well as new polysulfone cages (1.5 micro g/L), whereas no BPA was detected in water incubated in glass and used polypropylene cages. Finally, BPA exposure as a result of being housed in used polycarbonate cages produced a 16% increase in uterine weight in prepubertal female mice relative to females housed in used polypropylene cages, although the difference was not statistically significant. Our findings suggest that laboratory animals maintained in polycarbonate and polysulfone cages are exposed to BPA via leaching, with exposure reaching the highest levels in old cages.

  5. The damage process induced by swift heavy ion in polycarbonate

    Science.gov (United States)

    Sun, Youmei; Zhu, Zhiyong; Wang, Zhiguang; Liu, Jie; Jin, Yunfan; Hou, Mingdong; Wang, Ying; Duan, Jinglai

    2003-12-01

    To describe the damage process of polymer in the energetic heavy ion tracks by thermal spike model, polycarbonate (PC, Makrofol KG) foil stacks were irradiated with various swift heavy ions (1.158 GeV Fe 56, 1.755 GeV Xe 136 and 2.636 GeV U 238) in a very wide electronic stopping power range (from 1.9 to 17.1 keV/nm) and fluence range from 1 × 10 10 to 3 × 10 12 ions/cm 2. The amorphous processes and chemical degradation in the irradiated PC were studied by X-ray diffraction and Fourier transform infrared spectroscopy measurements. By applying the saturated track model, the mean damage radii of tracks of the amorphous and alkyne formation process were obtained for Fe, Xe and U ion irradiation, respectively. The results were validated by the thermal spike model. The analysis of the irradiated PC films shows that the predictions of the thermal spike model of Szenes are basically in quantitative agreement with the experimental results.

  6. In vitro biocompatiblity of modified polycarbonate as a biomaterial.

    Science.gov (United States)

    Vani, Kohila; Thomas, Susha; Prabhawathi, V; Boobalan, T; Sawant, Shilpa N; Doble, Mukesh

    2013-08-01

    Nitrated and aminated polycarbonates were prepared chemically, characterized and tested in vitro as a possible biomaterial. Adhesion of Staphylococcus aureus NCIM 5021, Escherichia coli NCIM 2931 and Proteus vulgaris NCIM 2813 and the presence of carbohydrate, protein, CFU and ATP on these surfaces were examined. Cytotoxicity of these surfaces was investigated by growing L929 mouse fibroblast cells. NO2-PC was more hydrophilic than un-PC and reduced adhesion of bacterial protein and carbohydrate. NH2-PC was the most hydrophilic surface biofilm prevention and increased proliferation of the fibroblast cells. The motility of all the three organisms decreased on aminated surface when compared to that on the other two. This study indicated that reducing the surface hydrophobicity alone was not sufficient to develop a biocompatible material, but providing favorable surface functional groups was also a necessary criterion. A strong correlation was observed between the hydrophobicity of the polymer surface and the zeta potential of the organism with bacterial attachment (CFU/ml). A multi-linear regression model with these two parameters was able to fit the observed bacterial attachment data well. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Anti-biofilm activity of Fe heavy ion irradiated polycarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, R.P. [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Hareesh, K., E-mail: appi.2907@gmail.com [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Bankar, A. [Department of Microbiology, Waghire College, Pune 412301 (India); Sanjeev, Ganesh [Microtron Centre, Department of Studies in Physics, Mangalore University, Mangalore 574166 (India); Asokan, K.; Kanjilal, D. [Inter University Accelerator Centre, Arun Asaf Ali Marg, New Delhi 110067 (India); Dahiwale, S.S.; Bhoraskar, V.N. [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Dhole, S.D., E-mail: sanjay@physics.unipune.ac.in [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India)

    2016-10-01

    Highlights: • PC films were irradiated by 60 and 120 MeV Fe ions. • Irradiated PC films showed changes in its physical and chemical properties. • Irradiated PC also showed more anti-biofilm activity compared to pristine PC. - Abstract: Polycarbonate (PC) polymers were investigated before and after high energy heavy ion irradiation for anti-bacterial properties. These PC films were irradiated by Fe heavy ions with two energies, viz, 60 and 120 MeV, at different fluences in the range from 1 × 10{sup 11} ions/cm{sup 2} to 1 × 10{sup 13} ions/cm{sup 2}. UV-Visible spectroscopic results showed optical band gap decreased with increase in ion fluences due to chain scission mainly at carbonyl group of PC which is also corroborated by Fourier transform infrared spectroscopic results. X-ray diffractogram results showed decrease in crystallinity of PC after irradiation which leads to decrease in molecular weight. This is confirmed by rheological studies and also by differential scanning calorimetric results. The irradiated PC samples showed modification in their surfaces prevents biofilm formation of human pathogen, Salmonella typhi.

  8. Influence of nitrogen on the tribological properties of a-C:H layers on the polycarbonate substrates

    Directory of Open Access Journals (Sweden)

    Rafal M. Nowak

    2008-12-01

    Full Text Available Polycarbonate (PC possesses many commercial applications. However, PC is still limited to non-abrasive and chemical-free environments due to its low hardness, low scratching resistance and high susceptibility to chemical attacks. To overcome this limitation, PC can be coated by hydrogenated amorphous carbon layers. The a-C:H layers have very attractive properties such as high hardness, infrared transparency, chemical inertness, low friction coefficients, and biocompatibility. Addition of nitrogen in the structure allows lowering internal stress and improve tribological properties of a-C:H layers. In this work, a-C:N:H layers were deposited from mixture CH4/N2 gases by RF PECVD method. Effects of the nitrogen incorporation on structure and tribological properties of deposited layers were investigated. The structure of layers were characterized by Fourier Transform Infrared spectroscopy (FTIR and X-ray photoelectron spectroscopy (XPS. The friction coefficient, wear resistance of a-C:H:N layers were estimated by tribometer in ball-on-disc configuration. The IR spectra of the obtained layers have demonstrated a presence of nitrogen bonded both to carbon and to hydrogen. A formation of the following bonds has been confirmed: -C≡N, -NH2, -C−NH2, >C=NH. They are all typical for a-C:N:H layers. The tribological tests have shown that the layers reduce the friction coefficient of the polycarbonate (up to 50 % and considerably improve wear resistance.

  9. Carbon nanotubes with silver nanoparticle decoration and conductive polymer coating for improving the electrical conductivity of polycarbonate composites

    KAUST Repository

    Patole, Archana S.

    2015-01-01

    We proposed a strategy to enhance the conductivity of polycarbonate by using three-phase hybrid metallic/non-metallic fillers. Ethylene diamine (EDA) functionalized multiwalled carbon nanotubes (MWCNT-EDA) are first decorated with silver nanoparticles. These Ag/ MWCNT-EDA fillers are then coated with a conductive layer of ethylene glycol treated PEDOT: PSS (poly [3,4-ethylenedioxythiophene]: poly [styrenesulfonate]) (EP). In such an approach, the MWCNT backbone is covered by a highly conductive coating made of Ag nanoparticles surrounded by EP. To understand how Ag and EP form a highly conductive coating, the effect of different wt% of Ag nanoparticles on EP was studied. Ag nanoparticles around the size of 128 ± 28 nmeffectively lowered the volume resistivity of bulk EP, resulting in a highly conducting Ag/EP blend. We found that in the final Ag/MWCNT-EDA/EP assembly, the EP coating enhances the electrical conductivity in two ways: (1) it is an efficient dispersing agent that helps in achieving a uniform dispersion of the Ag/MWCNT-EDA and (2) it acts as a conductive bridge between particles (Ag and MWCNT-EDA), reducing the particle to particle resistivity. When inserted into polycarbonate, this three-phase blend successfully reduced the volume resistivity of the polymer by two orders of magnitude compared with previous approaches.

  10. Synthesis and Characterization of Imidazolium Linear Bisphenol Polycarbonate Hydroxides for Anion Exchange Membrane.

    Science.gov (United States)

    Jang, Hohyoun; Hossain, Md Awlad; Lee, Soonho; Ha, Jaesung; Yoo, Jihoo; Kim, Kyungchul; Kim, Whangi

    2015-11-01

    A novel anion exchange membrane of imidazolium functionalized bisphenol polycarbonate was prepared for application in alkaline fuel cell. Di-imidazolium polycarbonate anionic membrane was synthesized by sequential interfacial polymerization, chloromethylation, substitution with 1-methylimidazole and ion exchange with 1.0 M KOH. Chloromethylation reaction was quantitative to achieve a high content of hydroxide ions. Introduction of conjugated imidazole ring in polymer plays an important role to improve both thermal and chemical stability. Bisphenol polycarbonate is a flexible polymer and shows a good solubility in polar organic solvent. The alkaline imidazolium bisphenol polycarbonate rendered an elevated molecular weight with excellent solubility in polar aprotic solvent. Different levels of substitution and ion exchange were investigated; the resulting membranes showed high ion exchange capacities (IECs) of up to 2.15 mmol g(-1). The imidazolium-functionalized copolymer membranes showed lower water affinity (14.2-42.8% at 30 degrees C) that satisfied an essential criterion for fuel cell application. The chemical structure of the imidazolium functionalized polycarbonate membrane was confirmed by 1H NMR spectroscopy, and also the membrane properties were evaluated by thermogravimetric analysis (TGA) and water uptake (WU), IEC and conductivity assessment. They exhibited hydroxide conductivity above 10(-2) S cm(-1) at room temperature and good chemical stability for up to five days without significant losses of ion conductivity.

  11. Modification of epoxy resins with thermoplastic segmented polycarbonate-based polyurethanes

    Directory of Open Access Journals (Sweden)

    Pavličević Jelena

    2014-01-01

    Full Text Available In this work, epoxy hybrid materials were synthesized by addition of thermoplastic segmented aliphatic polyurethanes with good elastic properties. The modified epoxy samples were obtained by curing of previously homogenized mixture of prepared polyurethane melts, epoxy resin and crosslinking agent Jeffamine D-2000. The influence of different weight content of polyurethanes (5, 10 and 15 wt. % compared to pure epoxy resin as well the influence of different hard segments of elastomers (20, 25 and 30 wt. % on the curing of modified epoxy systems was studied. The curing was followed by differential scanning calorimetry (DSC, in dynamic regime from 30 to 300°C, at three heating rates (5, 10 and 20°C/min. With the increase of hard segments content of polyurethanes added in higher concentration (10 and 15 wt. % into epoxy matrix, the temperature of maximum ratio of curing was shifted to lower values (from 205 to 179°C. Obtained DSC data were analyzed using two integral methods (Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose and one differential kinetic model (Friedman. The significant differences were observed in the second part of the epoxy curing (for the reaction degrees higher than 60 %, where the values of activation energies remarkably increase. The addition of polyurethane elastomers retarded the curing process due to decreased mobility of reactant molecules caused by higher viscosity of reaction mixture. By detailed analysis of determined kinetic parameters, it is concluded that the influence of slow diffusion is more pronounced in the presence of thermoplastic polycarbonate-based polyurethanes, which confirmed their effect on the mechanism of epoxy curing. The highest tensile strength and hardness showed the DGEBA modified with the polyurethane with highest hard segment content. Increasing the hard segment content of polyurethane and its concentration in matrix, the tensile strength of modified epoxy was increased. The elongation at break of

  12. The efficiency of night insulation using aerogel-filled polycarbonate panels during the heating season

    Science.gov (United States)

    Adelsberger, Kathleen

    Energy is the basis for modern life. All modern technology from a simple coffee maker to massive industrial facilities is powered by energy. While the demand for energy is increasing, our planet is suffering from the consequences of using fossil fuels to generate electricity. Therefore, the world is looking at clean energy and solar power to minimize this effect on our environment. However, saving energy is extremely important even for clean energy. The more we save the less we have to generate. Heat retention in buildings is one step towards achieving passive heating. Therefore, efforts are made to prevent heat from escaping buildings through the glass during cold nights. Movable insulation is a way to increase the insulation value of the glass to reduce heat loss towards the outdoor. This thesis examines the performance of the aerogel-filled polycarbonate movable panels in the Ecohawks building, a building located on the west campus of The University of Kansas. Onsite tests were performed using air and surface temperature sensors to determine the effectiveness of the system. Computer simulations were run by Therm 7.2 simulation software to explore alternative design options. A cost analysis was also performed to evaluate the feasibility of utilizing movable insulation to reduce the heating bills during winter. Results showed that sealed movable insulation reduces heat loss through the glazing by 67.5%. Replacing aerogel with XPS panels reduces this percentage to 64.3%. However, it reduces the cost of the insulation material by 98%.

  13. Ammonia modification for flotation separation of polycarbonate and polystyrene waste plastics.

    Science.gov (United States)

    Wang, Chong-Qing; Wang, Hui; Gu, Guo-Hua; Lin, Qing-Quan; Zhang, Ling-Ling; Huang, Luo-Luo; Zhao, Jun-Yao

    2016-05-01

    A promising method, ammonia modification, was developed for flotation separation of polycarbonate (PC) and polystyrene (PS) waste plastics. Ammonia modification has little effect on flotation behavior of PS, while it changes significantly that of PC. The PC recovery in the floated product drops from 100% to 3.17% when modification time is 13min and then rises to 100% after longer modification. The mechanism of ammonia modification was studied by contact angle, and Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) measurements. Contact angle of PC indicates the decline of PC recovery in the floated product is ascribed to an increase in surface wettability. FT-IR and XPS spectra suggest that ammonia modification causes chemical reactions occurred on PC surface. Flotation behavior of ammonia-modified PC and PS was investigated with respect to flotation time, frother concentration and particle sizes. Flotation separation of PC and PS waste plastics was conducted based on the flotation behavior of single plastic. PC and PS mixtures with different particle sizes are separated efficiently, implying that the technology possesses superior applicability to particle sizes of plastics. The purity of PS and PC is up to 99.53% and 98.21%, respectively, and the recovery of PS and PC is larger than 92.06%. A reliable, cheap and effective process is proposed for separation of PC and PS waste plastics. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Postpolymerization Modifications of Alkene-Functional Polycarbonates for the Development of Advanced Materials Biomaterials.

    Science.gov (United States)

    Thomas, Anthony W; Dove, Andrew P

    2016-12-01

    Functional aliphatic polycarbonates have attracted significant attention as materials for use as biomedical polymers in recent years. The incorporation of pendent functionality offers a facile method of modifying materials postpolymerization, thus enabling functionalities not compatible with ring-opening polymerization (ROP) to be introduced into the polymer. In particular, polycarbonates bearing alkene-terminated functional groups have generated considerable interest as a result of their ease of synthesis, and the wide range of materials that can be obtained by performing simple postpolymerization modifications on this functionality, for example, through radical thiol-ene addition, Michael addition, and epoxidation reactions. This review presents an in-depth appraisal of the methods used to modify alkene-functional polycarbonates postpolymerization, and the diversity of practical applications for which these materials and their derivatives have been used. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. AL-SX (H1616) Container Support: Out-gassing of Polyethylene and Polycarbonate Resins

    International Nuclear Information System (INIS)

    Story, G. Cook; Seibel, Leon; Domeier, Linda

    1999-01-01

    Out-gassing tests were carried out on samples of polyethylene and polycarbonate packaging components used within the AL-SX (H1616) shipping container and compared to known samples of high and low density polyethylene and polycarbonate. Polyethylene is used to fabricate the shipping container overpack for the MC3007A/MC4059 and 1X-Acorn; LEXANreg s ign polycarbonate (General Electric) is used to fabricate the lid of the Protective Container utilized to package the MC4213/MC4240 and MC4524 for shipment in the AL-SX (H1616). Pressure was monitored up to about 650 F and all the samples showed similar increases in pressure which were only slightly above those measured for control runs using no resin sample. None of the polymer samples showed out-gassing behavior that would lead to excessive pressure increases in the H1616 within that temperature range

  16. Polymeric compositional materials based on polycarbonate for units of devices for transform solar into thermal energy

    Directory of Open Access Journals (Sweden)

    V. I. Sytar

    2017-06-01

    Full Text Available Modern development of the industry is complicated without introduction of energy-saving technologies based on renewable natural energy sources. Solar and wind power plants, heat generators, solar collectors are wide spread in developed countries. One of it is device for transform solar into thermal energy. It is costly devices with low level of reliability and durability. Therefore actual tasks of this work are reduction cost of device for transform solar into thermal energy and increase it level of reliability and durability. These tasks are carried out by the way of substitution the main elements of device for transform solar into thermal energy by development polymeric compositional materials (PCM. As the polymer matrix is selected polycarbonate. This matrix is modified by silicon rubber and filled by graphite. The silicon rubber increase technological effectiveness by procedure of obtaining PCM. Graphite significantly increase tribotechnical properties of PCM in friction units with steel. Developed PCM can be recommended for application in main elements of device for transform solar into thermal energy, that lead to increasing of it level of reliability and durability.

  17. Polycarbonate surface cell's adhesion examination after Nd:YAG laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ramazani, S.A. Ahmad, E-mail: Ramazani@sharif.ir [Polymer Group, Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Mousavi, Seyyed Abbas, E-mail: Musavi@che.sharif.ir [Department of Chemistry, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Seyedjafari, Ehsan [Department of Biotechnology, University College of Science, University of Tehran (Iran, Islamic Republic of); Poursalehi, Reza [Department of Physics, University of Shahed, Tehran (Iran, Islamic Republic of); Sareh, Shohreh [Research Center of Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Silakhori, Kaveh [Laser Research Center, Atomic Energy Organization, Tehran (Iran, Islamic Republic of); Poorfatollah, Ali Akbar [Research Center of Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Shamkhali, Amir Nasser [Department of Chemistry, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

    2009-05-05

    Nd:YAG laser treatment was used in order to increase surface cell adhesion aspects of polycarbonate (PC) films prepared via melt process. The treatment was carried out under different wavelengths and beam diameters. ATR-FTIR and UV spectra obtained from different samples before and after laser treatment in air showed that laser irradiation has induced some chemical and physical changes in surface properties. The irradiated films were also characterized using scanning electron microscopy (SEM) and contact angle measurements. Effect of pulse numbers on the surface properties was also investigated. Cell culture test was used to evaluate cell adhesion property on the PC films before and after treatment. The results obtained from this test showed that after laser treatment, the cells were attached and proliferated extensively on the Nd:YAG laser treated films in comparison with the unmodified PC. Moreover, it was revealed that a decrease in the laser beam diameter and an increase in the irradiated pulse numbers increased surface wettability and caused a better cell attachment on the polymer surface. The obtained results also showed that a decrease in the laser beam diameter and an increase in the irradiated pulse numbers increased surface wettability and caused a better cell attachment on the polymer surface.

  18. Investigation of thermally stimulated properties of SHI beam irradiated polycarbonate/polystyrene double layered samples

    Science.gov (United States)

    Rathore, Bhupendra Singh; Gaur, Mulayam Singh; Singh, Kripa Shanker

    2011-12-01

    The double layered samples of polycarbonate/polystyrene (PC/PS) have been prepared by solvent casting method and irradiated with 55 MeV C 5+ beam at different ion fluences range from 1 × 10 11 to 1 × 10 13 ion/cm 2. The effect of swift heavy ion (SHI) beam in interfacial phenomena, phase change, dielectric relaxation, degradation temperature, stability, charge storage and transport mechanism of PC/PS pristine and irradiated double layered samples have been investigated by thermally stimulated discharge current (TSDC), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). TSDC show α, β-relaxation peaks shifted to the lower temperatures side with increase of fluence. The activation energy and relaxation time decrease, while the depolarization current and charge released increase with increase in the ion fluences. DSC curve show the glass transition temperature ( T g) and heat capacity decreases with increase in the ion fluences. The TGA characteristics represent the thermal stability, which is found to be decreased with increase in the ion fluences.

  19. Superposition approach for description of electrical conductivity in sheared MWNT/polycarbonate melts

    Directory of Open Access Journals (Sweden)

    M. Saphiannikova

    2012-06-01

    Full Text Available The theoretical description of electrical properties of polymer melts, filled with attractively interacting conductive particles, represents a great challenge. Such filler particles tend to build a network-like structure which is very fragile and can be easily broken in a shear flow with shear rates of about 1 s–1. In this study, measured shear-induced changes in electrical conductivity of polymer composites are described using a superposition approach, in which the filler particles are separated into a highly conductive percolating and low conductive non-percolating phases. The latter is represented by separated well-dispersed filler particles. It is assumed that these phases determine the effective electrical properties of composites through a type of mixing rule involving the phase volume fractions. The conductivity of the percolating phase is described with the help of classical percolation theory, while the conductivity of non-percolating phase is given by the matrix conductivity enhanced by the presence of separate filler particles. The percolation theory is coupled with a kinetic equation for a scalar structural parameter which describes the current state of filler network under particular flow conditions. The superposition approach is applied to transient shear experiments carried out on polycarbonate composites filled with multi-wall carbon nanotubes.

  20. Frictional and Optical Properties of Diamond-Like-Carbon Coatings on Polycarbonate

    International Nuclear Information System (INIS)

    Lin Zeng; Gao Ding; Ba Dechun; Wang Feng; Liu Chunming

    2013-01-01

    In this work, diamond-like-carbon (DLC) films were deposited onto polycarbonate (PC) substrates by radio-frequency plasma-enhanced chemical vapor deposition (RF PECVD), and silicon films were prepared between DLC and PC substrates by magnetron sputtering deposition so as to improve the adhesion of the DLC films. The deposited films were investigated by means of field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Subsequently, the following frictional and optical properties of the films were measured: the friction coefficient by using a ball-on-disk tribometer, the scratch hardness by using a nano-indenter, the optical transmittance by using a UV/visible spectrometer. The effects of incident power upon the frictional and optical properties of the films were investigated. Films deposited at low incident powers showed large optical gaps, which decreased with increasing incident power. The optical properties of DLC films correlated to the sp 2 content of the coatings. High anti-scratch properties were obtained at higher values of incident power. The anti-scratch properties of DLC films correlated to the sp 3 content of the coatings

  1. Chemical modification of polycarbonate induced by 1.4 GeV Ar ions

    International Nuclear Information System (INIS)

    Wang Yanbin; Jin Yunfan; Zhu Zhiyong; Liu Changlong; Sun Youmei; Wang Zhiguang; Hou Mingdong; Chen Xiaoxi; Zhang Chonghong; Liu Jie; Li Baoquan

    2000-01-01

    Polycarbonate foil stacks were irradiated with 1.4 GeV Ar ions at room temperature. The induced modifications in chemical structure were studied by Fourier transform infrared (FTIR) and ultraviolet/visible absorption (UV/VIS) spectroscopies. FTIR measurements reveal that material degradation through bond breaking are the main effects. Significant reduction in absorbance of the typical infrared bands is observed at energy densities higher than 8x10 22 eV/cm 3 . Alkyne end groups are produced by the irradiations and the electronic energy loss threshold for production of the alkyne end group is found to be below 0.61 keV/nm. UV/VIS measurements indicate a shifting of the absorption edge from ultraviolet towards visible and a strong increase of absorbance in the ultraviolet and visible regions. The irradiation induced changes in absorbance at wavelengths of 380, 450 and 500 nm follow roughly linear relationship with fluence and scale rather good with the square of electronic energy loss. The results are briefly discussed

  2. Data in support of preparation and functionalization of a clickable polycarbonate monolith

    Directory of Open Access Journals (Sweden)

    Yuanrong Xin

    2016-06-01

    Full Text Available This data article provides supplementary figures to the research article entitled, “Phase separation approach to a reactive polycarbonate monolith for “click” modifications” (Xin et al., Polymer, 2015, doi:10.1016/j.polymer.2015.04.008. Here, the nitrogen adsorption/desorption isotherms of the prepared porous polycarbonate monolith are shown to classify its inner structure and calculate the specific surface area. The monoliths were modified by using the thiol-ene click chemistry and the olefin metathesis, which was examined by contact angle measurements, FT-IR, solid state 13C NMR spectroscopy as well as thermogravimetric analysis.

  3. Influences of layer thickness on the compatibility and physical properties of polycarbonate/polystyrene multilayered film via nanolayer coextrusion

    Science.gov (United States)

    Cheng, Junfeng; Chen, Zhiru; Zhou, Jiaqi; Cao, Zheng; Wu, Dun; Liu, Chunlin; Pu, Hongting

    2018-05-01

    The effects of layer thickness on the compatibility between polycarbonate (PC) and polystyrene (PS) and physical properties of PC/PS multilayered film via nanolayer coextrusion are studied. The morphology of multilayered structure is observed using a scanning electron microscope. This multilayered structure may have a negative impact on the transparency, but it can improve the water resistance and heat resistance of film. To characterize the compatibility between PC and PS, differential scanning calorimetry is used to measure the glass transition temperature. The compatibility is found to be improved with the decrease of layer thickness. Therefore, the viscosity of multilayered film is also reduced with the decrease of layer thickness. In addition, the multilayered structure can improve the tensile strength with the increase of layer numbers. Because of the complete and continuous layer structure of PC, the PC/PS multilayered film can retain its mechanical strength at the temperature above Tg of PS.

  4. 21 CFR 175.365 - Vinylidene chloride copolymer coatings for polycarbonate film.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Vinylidene chloride copolymer coatings for polycarbonate film. 175.365 Section 175.365 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS OF COATINGS Substances for...

  5. Polycarbonate-based polyurethane elastomers: temperature-dependence of tensile properties

    Czech Academy of Sciences Publication Activity Database

    Hrdlička, Z.; Kuta, A.; Poreba, Rafal; Špírková, Milena

    2014-01-01

    Roč. 68, č. 2 (2014), s. 233-238 ISSN 0366-6352 R&D Projects: GA ČR GAP108/10/0195 Institutional support: RVO:61389013 Keywords : polyurethane * elastomer * polycarbonate diol Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.468, year: 2014

  6. Medium chain glycerides of coconut oil for microwave-enhanced conversion of polycarbonate into polyols

    Czech Academy of Sciences Publication Activity Database

    Beneš, Hynek; Paruzel, Aleksandra; Trhlíková, Olga; Paruzel, Bartosz

    2017-01-01

    Roč. 86, January (2017), s. 173-187 ISSN 0014-3057 R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : medium chain triglycerides * coconut oil * polycarbonate Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 3.531, year: 2016

  7. Pyrolysis kinetics and thermal decomposition behavior of polycarbonate - a TGA-FTIR study

    Directory of Open Access Journals (Sweden)

    Apaydin-Varol Esin

    2014-01-01

    Full Text Available This study covers the thermal degradation of polycarbonate by means of Thermogravimetric Analyzer coupled with Fourier transform infrared spectrometer (TGA-FTIR. Thermogravimetric analysis of polycarbonate was carried out at four different heating rates of 5, 10, 15, and 20°C per minute from 25°C to 1000°C under nitrogen atmosphere. The results indicated that polycarbonate was decomposed in the temperature range of 425-600°C. The kinetic parameters, such as activation energy, pre-exponential factor and reaction order were determined using five different kinetic models; namely Coast-Redfern, Friedman, Kissinger, Flynn-Wall-Ozawa (FWO, and Kissinger-Akahira-Sunose (KAS. Overall decomposition reaction order was determined by Coats-Redfern method as 1.5. Average activation energy was calculated as 150.42, 230.76, 216.97, and 218.56 kJ/mol by using Kissinger, Friedman, FWO, and KAS models, respectively. Furthermore, the main gases released during the pyrolysis of polycarbonate were determined as CO2, CH4, CO, H2O, and other lower molecular weight hydrocarbons such as aldehydes, ketones and carbonyls by using thermogravimetric analyzer coupled with Fourier transform infrared spectrometer.

  8. Polycarbonate as an Elasto-Plastic Material Model for Simulation of the Microstructure Hot Imprint Process

    Directory of Open Access Journals (Sweden)

    Rokas Šakalys

    2013-08-01

    Full Text Available The thermal imprint process of polymer micro-patterning is widely applied in areas such as manufacturing of optical parts, solar energy, bio-mechanical devices and chemical chips. Polycarbonate (PC, as an amorphous polymer, is often used in thermoforming processes because of its good replication characteristics. In order to obtain replicas of the best quality, the imprint parameters (e.g., pressure, temperature, time, etc. must be determined. Therefore finite element model of the hot imprint process of lamellar periodical microstructure into PC has been created using COMSOL Multiphysics. The mathematical model of the hot imprint process includes three steps: heating, imprinting and demolding. The material properties of amorphous PC strongly depend on the imprint temperature and loading pressure. Polycarbonate was modelled as an elasto-plastic material, since it was analyzed below the glass transition temperature. The hot imprint model was solved using the heat transfer and the solid stress-strain application modes with thermal contact problem between the mold and polycarbonate. It was used for the evaluation of temperature and stress distributions in the polycarbonate during the hot imprint process. The quality of the replica, by means of lands filling ratio, was determined as well.

  9. Aliphatic polycarbonate-based polyurethane elastomers and nanocomposites. II. Mechanical, thermal, and gas transport properties

    Czech Academy of Sciences Publication Activity Database

    Poreba, Rafal; Špírková, Milena; Brožová, Libuše; Lazić, N.; Pavličevič, Jelena; Strachota, Adam

    2013-01-01

    Roč. 127, č. 1 (2013), s. 329-341 ISSN 0021-8995 R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane elastomer * nanocomposite * polycarbonate diol Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.640, year: 2013

  10. Synthesis and characterisation of scintillating microspheres made of polystyrene/polycarbonate for 222Rn measurements

    International Nuclear Information System (INIS)

    Pelay, Eduard; Garcia, Jose Francisco; Mitev, Krasimir; Dutsov, Chavdar; Georgiev, Strahil; Tsankov, Ludmil

    2017-01-01

    Several studies have demonstrated that polycarbonate-based polymers have good capacities for the absorption of 222 Rn. Meanwhile, polystyrene polymers are reported to be the most appropriate for developing plastic scintillator materials for the detection of radioactivity. The objective of this work was to develop plastic scintillators in the form of microspheres (PSm) composed of polystyrene and polycarbonate that could be used to measure 222 Rn and improve this performance thanks to the combination of characteristics of both polymers. Our results show that PSm of polystyrene and polycarbonate can be made via the evaporation/extraction method, despite the two polymers not being miscible. From the point of view of the radioactive measurements, we observed that the addition of polycarbonate causes quenching, although it does not significantly affect the detection efficiency for alpha and high-energy beta emitters. From the point of view of 222 Rn absorption, we observed that synthesis of the PSm through the evaporation/extraction method changes the 222 Rn absorption of the raw material. This result demonstrates that the method of production of the polymer and the resulting physical characteristics are a key parameter for its final 222 Rn absorption properties. (author)

  11. The use of birefringence for predicting the stiffness of injection molded polycarbonate discs

    NARCIS (Netherlands)

    Neves, N.M.; Pouzada, A.S.; Voerman, J.H.D.; Powell, P.C.

    1998-01-01

    Polycarbonate discs were injection molded with different sets of molding conditions. The parameters studied were the flow rate, melt- and mold-temperature. The discs were subjected to three point support flexural tests. Those tests are specially intended for injection molded discs because of their

  12. Short term evaluation of an anatomically shaped polycarbonate urethane total meniscus replacement in a goat model

    NARCIS (Netherlands)

    Vrancken, A.C.T.; Madej, W.; Hannink, G.; Verdonschot, Nicolaas Jacobus Joseph; van Tienen, T.G.; Buma, P.

    2015-01-01

    Purpose: Since the treatment options for symptomatic total meniscectomy patients are still limited, an anatomically shaped, polycarbonate urethane (PCU), total meniscus replacement was developed. This study evaluates the in vivo performance of the implant in a goat model, with a specific focus on

  13. Release of (14)C-labelled carbon nanotubes from polycarbonate composites.

    Science.gov (United States)

    Rhiem, Stefan; Barthel, Anne-Kathrin; Meyer-Plath, Asmus; Hennig, Michael P; Wachtendorf, Volker; Sturm, Heinz; Schäffer, Andreas; Maes, Hanna M

    2016-08-01

    Waste disposal of carbon nanotube (CNT) containing products is expected to be the most important pathway for release of CNTs into the environment. In the present work, the use of radiolabelled CNTs ((14)C-CNT) for polycarbonate polymer nanocomposites with 1 wt% (14)C-CNT content allowed for the first time to quantify and differentiate the CNT release according to the type of impact along the materials' ageing history. After an initial exposure of the nanocomposite by solar-like irradiation, further environmental impacts were applied to composite material. They aimed at mimicking disposal site conditions that may induce further ageing effects and CNT release. This study included shaking in water, rapid temperature changes, soaking in humic acid solution as well as waste water effluent, and, finally, gentle mechanical abrasion. All ageing impacts were applied sequentially, both on pristine (control) and on solar-irradiated nanocomposites. All experiments were accompanied by absolute quantification of radioactive release as well as chemical and morphological analyses of the nanocomposite surfaces using infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The morphological analysis showed that spectral irradiation can uncover CNT networks on the outer nanocomposite surface layers by polymer degradation. After having subjected the solar-irradiated nanocomposite to all studied disposal site effect, the total radioactive release was quantified to amount to 64 mg CNT/m(2), whereas only 0.8 mg CNT/m(2) were found for the un-irradiated control sample. Solar degradation of polymers was thus found to significantly increase the propensity of the studied polymer nanocomposites to release CNTs during ageing effects at the product's end-of-life typical for disposal sites. Copyright © 2016. Published by Elsevier Ltd.

  14. Fluorocarbon chain end-capped poly(carbonate urethane)s as biomaterials: blood compatibility and chemical stability assessments.

    Science.gov (United States)

    Xie, Xingyi; Wang, Ruifang; Li, Jiehua; Luo, Liang; Wen, Da; Zhong, Yinping; Zhao, Changsheng

    2009-04-01

    Previous work has shown the synthesis of fluorocarbon chain (CF(3)(CF(2))(6)CH(2)O-) end-capped poly(carbonate urethane)s (FPCUs) and confirmed the presence of a novel bilayered surface structure in FPCUs, that is, the top fluorocarbon and subsurface hard segment layers (Xie et al., J Biomed Mater Res Part A 2008; 84:30-43). In this work, the effects of such surface structure on blood compatibility were investigated using hemolytic test and platelet adhesion analysis. The chemical stability of the polymers was also determined by Zhao's glass wool-H(2)O(2)/CoCl(2) test and phosphate-buffered saline (PBS, pH = 3.1-3.3) treatment. One of the FPCUs, FPCU-A, and two control materials, a poly(ether urethane) (PEU) and a poly(carbonate urethane) (PCU), were investigated. No significant difference in hemolytic indices was observed among the three materials, whereas the adherent density and deformation of platelets were much lower on FPCU-A compared with on PCU and PEU. Severe surface cracking and surface buckling developed in prestressed PEU and PCU films after H(2)O(2)/CoCl(2) treatment, respectively, whereas smooth surface was observed for the FPCU-A. PBS incubation resulted in parallel ridge-like morphology in PCU whereas PEU and FPCU-A retained their smooth surfaces. Under relatively high stress conditions, all the materials developed well-oriented strip-like surface patterns. Results from ATR-FTIR spectra revealed a surface oxidation mechanism as described in literature. However, observations of universal decrease of molecular weights under stress conditions further suggested the presence of another bulk stress oxidation mechanism. Regardless the degradation mechanisms involved, the unique bilayered surface structure really improved the blood compatibility and chemical stability of FPCU-A, indicating that further in vivo investigations are worthwhile.

  15. Modification induced by gamma irradiation in Bayfol CR 1-4 polycarbonate

    Science.gov (United States)

    Nouh, S. A.; Bahareth, Radiyah A.

    2013-04-01

    Bayfol CR 1-4 polycarbonate is a class of polymeric solid state nuclear track detector which has many applications in various radiation detection fields. Samples from sheets of Bayfol have been irradiated with gamma doses ranging from 100 to 620 kGy. The structural modifications in the gamma-irradiated Bayfol samples have been studied as a function of dose, using different characterization techniques such as X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, intrinsic viscosity and refractive index. The results indicate that the carbonyl group (C˭O) degraded under irradiation up to 200 kGy. This degradation, reported by FTIR spectroscopy enhanced the degree of ordering in the degraded samples as revealed by the XRD technique. Above 200 and up to 620 kGy, cross-linking is achieved, leading to an increase in the intrinsic viscosity from 0.41 to 0.78 at 35°C, indicating an increase in the average molecular mass. On the other hand, the resultant effect of gamma irradiation on the thermal properties of Bayfol has been investigated using thermo-gravimetric analysis, results indicating that the gamma irradiation in the dose range 200-620 kGy led to a more compact structure of Bayfol polymer, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition due to cross-linking. In addition, the V-I characteristics of the polymer samples were performed, results indicated that at higher voltage, the conduction mechanism of Bayfol CR 1-4 was identified as the Poole-Frenkel type.

  16. Opto-structural characterization of proton (3 MeV) irradiated polycarbonate and polystyrene

    Science.gov (United States)

    Singh, Lakhwant; Singh Samra, Kawaljeet

    2008-03-01

    Polycarbonate (Makrofol-N) and polystyrene thin films were irradiated with protons (3 MeV) under vacuum at room temperature with the fluence ranging from 1×10 14 to 1×10 15 protons cm -2. The change in optical properties, degradation of the functional groups and crystallinity of the proton-irradiated polymers were investigated with UV-vis, Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) techniques, respectively. The UV-vis analysis revealed that the optical band gap of irradiated Makrofol-N is reduced by 30% as compared to 27.5% in polystyrene at highest fluence of 1×10 15 protons cm -2, owing to higher electronic energy loss of protons in Makrofol-N. The calculations of the number of carbon atoms per conjugation length, N and number of carbon atoms per clusters, M embedded in the network of polymers further revealed that Makrofol-N is more modified as compared to polystyrene on proton irradiation. FTIR results reveal the reduction in absorption intensity of the main characteristic bands of both the polymers after irradiation. The proton-irradiated Makrofol-N shows a strong decrease of almost all of its characteristic absorption bands at about 1×10 14 protons cm -2. Beyond a critical dose an increase of almost all its characteristic bands are noticed, however, no such effect had been observed in polystyrene at this particular fluence. Appearance of new -OH groups was observed at the higher fluences in the FTIR spectra of both proton-irradiated polymers. XRD measurements show the decrease of the main peak intensity and the crystallite size, confirming the increase of amorphization in polymers under irradiation.

  17. Short Term Evaluation of an Anatomically Shaped Polycarbonate Urethane Total Meniscus Replacement in a Goat Model.

    Directory of Open Access Journals (Sweden)

    A C T Vrancken

    Full Text Available Since the treatment options for symptomatic total meniscectomy patients are still limited, an anatomically shaped, polycarbonate urethane (PCU, total meniscus replacement was developed. This study evaluates the in vivo performance of the implant in a goat model, with a specific focus on the implant location in the joint, geometrical integrity of the implant and the effect of the implant on synovial membrane and articular cartilage histopathological condition.The right medial meniscus of seven Saanen goats was replaced by the implant. Sham surgery (transection of the MCL, arthrotomy and MCL suturing was performed in six animals. The contralateral knee joints of both groups served as control groups. After three months follow-up the following aspects of implant performance were evaluated: implant position, implant deformation and the histopathological condition of the synovium and cartilage.Implant geometry was well maintained during the three month implantation period. No signs of PCU wear were found and the implant did not induce an inflammatory response in the knee joint. In all animals, implant fixation was compromised due to suture breakage, wear or elongation, likely causing the increase in extrusion observed in the implant group. Both the femoral cartilage and tibial cartilage in direct contact with the implant showed increased damage compared to the sham and sham-control groups.This study demonstrates that the novel, anatomically shaped PCU total meniscal replacement is biocompatible and resistant to three months of physiological loading. Failure of the fixation sutures may have increased implant mobility, which probably induced implant extrusion and potentially stimulated cartilage degeneration. Evidently, redesigning the fixation method is necessary. Future animal studies should evaluate the improved fixation method and compare implant performance to current treatment standards, such as allografts.

  18. Improvement of the mechanical and thermal properties of the metallized polycarbonate capacitor

    Science.gov (United States)

    Kellerman, H. J.

    1977-01-01

    Changes were studied which enable polycarbonate metallized film capacitors to withstand 500 thermal shock cycles while maintaining electrical characteristic integrity without becoming intermittent, and without losing hermeticity. The task was for metallized polycarbonate film capacitors designed to meet MIL-C-39022/9 and MIL-C-83421/1. The capacitor design improvements implemented were the insertion of a rubber washer between spray cap and end seal and the utilization of a flexible lead assembly. One hundred fifty capacitors incorporating the design improvements were manufactured and subsequently underwent 500 thermal shock cycles. One hundred forty nine capacitors survived the test. Failure analysis revealed that the lone failure was due to a poor solder joint, initially detected in pre-screening tests as having poor dissipation factor and equivalent series resistance measurement readings.

  19. Evaluation of polycarbonate substrate hologram recording medium regarding implication of birefringence and thermal expansion

    Science.gov (United States)

    Toishi, Mitsuru; Tanaka, Tomiji; Fukumoto, Atsushi; Sugiki, Mikio; Watanabe, Kenjiro

    2007-02-01

    In this paper, we evaluate photopolymer media using a polycarbonate (PC) substrate. In holographic data storage medium, substrates that sandwich the photopolymer material are needed to protect the photopolymer material against exogenous shock and open air. An optical glass such as BK-7 is normally used as a substrate, but a PC substrate has a cost advantage and is easy to fabricate compared with optical glass. For holographic recording and reading, however, the high birefringence and high thermal expansion of a PC substrate are significant problems. First, we analyze the degree of degradation of output power by the polarization change and estimate the threshold value of birefringence to record hologram normally. Next, we estimate the temperature tolerance of hologram readout with polycarbonate substrate hologram medium. These analyses results indicate the possible usage of the PC substrate as holographic recording media.

  20. Swift heavy ion induced modification in polycarbonate membrane for gas separation

    International Nuclear Information System (INIS)

    Rajesh Kumar; Prasad, Rajendra; Vijay, Y.K.; Das, D.

    2003-01-01

    Polymeric membranes are extensively used for commercial gas separation applications. Makrofol-KG (polycarbonate) is a glassy polymer. 40 μm thick sheet of Makrofol-KG was irradiated with 40 Ar (14.9 MeV/n) of fluence 10 3 ions/cm 2 and 20 μm thick sheet with 5.3 MeV α-particles of fluence 10 7 ions/cm 2 . The permeability of these polycarbonate membranes for H 2 and CO 2 was measured and also after etching in 6 N NaOH at 60 degC for different periods. Permeability is found to be increased with etching time. At a definite time, critical etching time, the permeability rapidly increases in PC. Positron annihilation lifetimes for unirradiated and irradiated membranes were measured with fast fast coincidence system to study the correlation of free volume hole concentration with gas separation properties. (author)

  1. A direct technique for fabricating esthetic anterior fixed provisional restorations using polycarbonate veneers.

    Science.gov (United States)

    Bidra, Avinash S; Manzotti, Anna

    2012-06-01

    Fabrication of esthetic interim restorations by a chairside technique often challenges the clinician with regard to the required time and skills, as well as meeting the expectations of the patient. Autopolymerizing polymethyl methacrylate resin has been reported to be the most popular material for fabricating provisional restorations. However, this material does not routinely yield esthetic provisional restorations via a chairside technique. This article describes a simple technique to overcome some of the disadvantages of this material by using prefabricated polycarbonate facings backed with autopolymerizing acrylic resin. This technique can be used chairside for fabricating esthetic anterior interim restorations, utilizing the beneficial properties of both materials. It exploits the manufactured smooth-surface finish, superior esthetics, color stability, and durability of polycarbonate facings, as well as the marginal adaptation, strength, and low cost of autopolymerizing acrylic resin.

  2. Transmission of Fast Highly Charged Ions through a Single Glass Macrocapillary and Polycarbonate Nanocapillary Foils

    Science.gov (United States)

    Ayyad, A. M.; Dassanayake, B. S.; Keerthisinghe, D.; DeSilva, G. G.; Elkafrawy, T.; Kayani, N.; Tanis, J. A.

    2012-11-01

    Transmission of 3 MeV protons and 16 MeV O5+ ions through a single glass macrocapillary and a polycarbonate nanocapillary foil has been investigated. Results show that 3 MeV protons transmit through the capillary and the foils with little or no energy loss, while 16 MeV O5+ ions show transmission through the capillary and the foil with energy losses that vary with the tilt angle, and there are also changes in the charge state.

  3. The phase structure of novel polycarbonate-based polyurethane-organoclay nanocomposites

    Czech Academy of Sciences Publication Activity Database

    Pavličević, J.; Sinadinović-Fišer, S.; Špírková, Milena; Budinski-Simendic, J.; Borota, O.; Janković, M.; Knez, Ž.

    560/561, 2012 (2012), s. 771-775 ISSN 1022-6680. [2012 Spring International Conference on Material Sciences and Technology (MST-S). Xi'an, 27.05.2012-30.05.2012] R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : polycarbonate-based polyurethane * hydrogen bonds * bentonite Subject RIV: CD - Macromolecular Chemistry

  4. Structural characterization of polycarbonates for membrane applications by atomic level simulation

    Energy Technology Data Exchange (ETDEWEB)

    Gentile, F.T.; Arizzi, S.; Suter, U.W. [ETH-Zentrum, Zuerich (Switzerland). Inst. fuer Polymere; Ludovice, P.J. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Chemical Engineering

    1995-12-01

    Polycarbonate polymers are desirable for use in membrane applications for separating gas mixtures due to their unique properties. Two commercially important membrane polymers, the tetramethyl (TMPC) and tetrabromo (TBPC) derivatives of Bisphenol A polycarbonate, were studied with computer simulation. The volume available to various gas diffusants in these polymers was characterized by calculating the volume of clusters of Delauney tetrahedra between the atoms of an ensemble of bulk molecular mechanics models of the polymer. The inverse of this available volume correlated with the diffusivity of various gases in these polymers. This correlation was able to qualitatively reproduce the gas diffusion consistent with the superior diffusivity and superior selectivity of TMPC and TBPC, respectively. Analysis of the structure of the two polymers suggests a more ordered packing of the TMPC chain which is consistent with the experimentally observed trend in which inhibited packing leads to increased selectivity for gas diffusion in polymers. Despite the model`s neglect of the thermal motion of the polymer, it has potential for use as a tool to suggest other perturbations in polycarbonate structure that may produce superior properties.

  5. The role of polycarbonate monomer bisphenol-A in insulin resistance

    Directory of Open Access Journals (Sweden)

    Milos Pjanic

    2017-09-01

    Full Text Available Bisphenol A (BPA is a synthetic unit of polycarbonate polymers and epoxy resins, the types of plastics that could be found in essentially every human population and incorporated into almost every aspect of the modern human society. BPA polymers appear in a wide range of products, from liquid storages (plastic bottles, can and glass linings, water pipes and tanks and food storages (plastics wraps and containers, to medical and dental devices. BPA polymers could be hydrolyzed spontaneously or in a photo- or temperature-catalyzed process, providing widespread environmental distribution and chronic exposure to the BPA monomer in contemporary human populations. Bisphenol A is also a xenoestrogen, an endocrine-disrupting chemical (EDC that interferes with the endocrine system mimicking the effects of an estrogen and could potentially keep our endocrine system in a constant perturbation that parallels endocrine disruption arising during pregnancy, such as insulin resistance (IR. Gestational insulin resistance represents a natural biological phenomenon of higher insulin resistance in peripheral tissues of the pregnant females, when nutrients are increasingly being directed to the embryo instead of being stored in peripheral tissues. Gestational diabetes mellitus may appear in healthy non-diabetic females, due to gestational insulin resistance that leads to increased blood sugar levels and hyperinsulinemia (increased insulin production from the pancreatic beta cells. The hypothesis states that unnoticed and constant exposure to this environmental chemical might potentially lead to the formation of chronic low-level endocrine disruptive state that resembles gestational insulin resistance, which might contribute to the development of diabetes. The increasing body of evidence supports the major premises of this hypothesis, as exemplified by the numerous publications examining the association of BPA and insulin resistance, both epidemiological and

  6. Helium ion distributions in a 4 kJ plasma focus device by 1 mm-thick large-size polycarbonate detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sohrabi, M., E-mail: dr_msohrabi@yahoo.com; Habibi, M.; Ramezani, V.

    2014-11-14

    Helium ion beam profile, angular and iso-ion beam distributions in 4 kJ Amirkabir plasma focus (APF) device were effectively observed by the unaided eyes and studied in single 1 mm-thick large-diameter (20 cm) polycarbonate track detectors (PCTD). The PCTDs were processed by 50 Hz–HV electrochemical etching using a large-size ECE chamber. The results show that helium ions produced in the APF device have a ring-shaped angular distribution peaked at an angle of ∼±60° with respect to the top of the anode. Some information on the helium ion energy and distributions is also provided. The method is highly effective for ion beam studies. - Highlights: • Helium iso-ion beam profile and angular distributions were studied in the 4 kJ APF device. • Large-area 1 mm-thick polycarbonate detectors were processed by 50 Hz-HV ECE. • Helium ion beam profile and distributions were observed by unaided eyes in a single detector. • Helium ion profile has ring-shaped distributions with energies lower at the ring location. • Helium iso-ion track density, diameter and energy distributions are estimated.

  7. Chemical etching studies of a Brazilian polycarbonate to fast neutron detection

    Energy Technology Data Exchange (ETDEWEB)

    Souto, E.B.; Campos, L.L. [Instituto de Pesquisas Energeticas e Nucleares, IPEN- CNEN/SP Radiation Metrology Center (CMR) Av. Prof. Lineu Prestes, 2242 CEP: 05508-000 Sao Paulo - SP (Brazil)]. e-mail: ebsouto@ipen.br

    2006-07-01

    The Dosimetric Materials Laboratory (LMD) of the Radiation Metrology Center (CMR) is developing a personal dosimeter for fast neutrons using the technique of solid state nuclear track detectors (SSNTD). This technique is based on the recorded damage (tracks) in dielectric materials due to the impact of charged particles. The tracks are revealed and amplified for visualization in optic microscope through a technique known as chemical etching. The LMD is investigating a Brazilian commercial polycarbonate as a new passive fast neutron's detector in substitution to the traditional materials, as the cellulose nitrate LR-115 and the polycarbonates Makrofol and CR-39. The variation of the etching parameters (chemical solution, time and temperature) alters the response of the material; the best revelation conditions provide the best relationship among the amount of revealed tracks, their clearness and the time spent for this. The polycarbonate studied is a resin of same chemical monomer of Makrofol (C,6H,403). Samples of 3 x 1 cm{sup 2} of the polycarbonate were irradiated with 5 mSv of fast neutrons ({sup 241}Am-Be) and revealed with the chemical solution PEW-40 (15% KOH, 45% H{sub 2}O, 40% C{sub 2}H{sub 5}OH), commonly used for Makrofol. The studied etching parameters were time and temperature. Groups of four samples were revealed at temperatures of 50, 65, 75, 90 and 100 C with etching times varying from one to six hours. The used track's counting procedure was that referred in the literature. The best response to fast neutrons was obtained at 75 C; in spite of their similar answers, smaller temperatures join larger uncertainties in the track's counting and poorer clearness. At this temperature, the number of revealed tracks increases with the etching time approximately until a plateau at three hours. For etching times higher than four hours the polycarbonate presents overlap of tracks. If the temperature is adjusted to 75 C, the etching time should be in

  8. Characterizing the reinforcement mechanisms in multiwall nanotube/polycarbonate composites across different length and time scales

    Science.gov (United States)

    Duncan, Renee Kelly

    The enthusiasm and interest in the potential properties of nanotube (NT)/polymer composites are based on several factors, including the potential for unsurpassed enhancements in mechanical properties together with electrical, thermal and optical properties. Using multiwall nanotubes (MWNTs) grown to a long aspect ratio, the study found that fragmentation tests can be completed in a similar manner to traditional fiber composites. It was found that the fragmentation length does not depend on the angle of the nanotube to the loading direction hence the ISS does not change with the orientation angle of the nanotube in the composite. A critical aspect ratio of 100 and 300 for untreated nanotubes (ARNT) and treated nanotubes (EPNT), respectively was also measured. For nanotubes that are well dispersed in the polycarbonate, it was observed at a critical angle of 60° that there was a change in failure mechanism from pullout to fracture of the nanotubes due to bending shear. Because the tensile strength of a MWNT is unknown a cumulative distribution was used to characterize the relative interfacial shear strength as a function of nanotube chemical modification. The second goal of this thesis is to use Dynamic Mechanical Thermal Analysis (DMTA) with controlled aspect ratios of multiwall nanotubes (MWNT) to isolate and quantify the effects of the interfacial region on modulus enhancements in nanotube-reinforced composites. One major finding of this study was that the shortest aspect ratio showed a significantly broadened relaxation spectrum than the longer aspect ratio nanotubes, despite the longer aspect ratio nanotubes being more percolated at the given weight percent. There is also a direct correlation between the free space parameter of the short aspect ratio nantoubes network and broadening of the relaxation spectrum, concluded to be a result of increased interaction of the interfacial polymer. The study found agreement with the premise that at a constant filler weight

  9. Mechanical, Electromagnetic, and X-ray Shielding Characterization of a 3D Printable Tungsten-Polycarbonate Polymer Matrix Composite for Space-Based Applications

    Science.gov (United States)

    Shemelya, Corey M.; Rivera, Armando; Perez, Angel Torrado; Rocha, Carmen; Liang, Min; Yu, Xiaoju; Kief, Craig; Alexander, David; Stegeman, James; Xin, Hao; Wicker, Ryan B.; MacDonald, Eric; Roberson, David A.

    2015-08-01

    Material-extrusion three-dimensional (3D) printing has recently attracted much interest because of its process flexibility, rapid response to design alterations, and ability to create structures "on-the-go". For this reason, 3D printing has possible applications in rapid creation of space-based devices, for example cube satellites (CubeSat). This work focused on fabrication and characterization of tungsten-doped polycarbonate polymer matrix composites specifically designed for x-ray radiation-shielding applications. The polycarbonate-tungsten polymer composite obtained intentionally utilizes low loading levels to provide x-ray shielding while limiting effects on other properties of the material, for example weight, electromagnetic functionality, and mechanical strength. The fabrication process, from tungsten functionalization to filament extrusion and material characterization, is described, including printability, determination of x-ray attenuation, tensile strength, impact resistance, and gigahertz permittivity, and failure analysis. The proposed materials are uniquely advantageous when implemented in 3D printed structures, because even a small volume fraction of tungsten has been shown to substantially alter the properties of the resulting composite.

  10. Investigation of the genotoxicity of substances migrating from polycarbonate replacement baby bottles to identify chemicals of high concern.

    Science.gov (United States)

    Mertens, Birgit; Simon, Coraline; Van Bossuyt, Melissa; Onghena, Matthias; Vandermarken, Tara; Van Langenhove, Kersten; Demaegdt, Heidi; Van Hoeck, Els; Van Loco, Joris; Vandermeiren, Karin; Covaci, Adrian; Scippo, Marie-Louise; Elskens, Marc; Verschaeve, Luc

    2016-03-01

    Due to the worldwide concern that bisphenol A might act as an endocrine disruptor, alternative materials for polycarbonate (PC) have been introduced on the European market. However, PC-replacement products might also release substances of which the toxicological profile--including their genotoxic effects--has not yet been characterized. Because a thorough characterization of the genotoxic profile of all these substances is impossible in the short term, a strategy was developed in order to prioritize those substances for which additional data are urgently needed. The strategy consisted of a decision tree using hazard information related to genotoxicity. The relevant information was obtained from the database of the European Chemicals Agency (ECHA), in silico prediction tools (ToxTree and Derek Nexus(TM)) and the in vitro Vitotox(®) test for detecting DNA damage. By applying the decision tree, substances could be classified into different groups, each characterized by a different probability to induce genotoxic effects. Although none of the investigated substances could be unequivocally identified as genotoxic, the presence of genotoxic effects could neither be excluded for any of them. Consequently, all substances require more data to investigate the genotoxic potential. However, the type and the urge for these data differs among the substances. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Separation of polycarbonate and acrylonitrile–butadiene–styrene waste plastics by froth flotation combined with ammonia pretreatment

    International Nuclear Information System (INIS)

    Wang, Chong-qing; Wang, Hui; Liu, Qun; Fu, Jian-gang; Liu, You-nian

    2014-01-01

    Highlights: • Ammonia treatment changes selectively floatability of PC. • The effects of ammonia on PC were investigated through contact angle and XPS. • Reactions between ammonia and PC surface make PC more hydrophilic. • PC and ABS mixtures with different particle sizes were separated effectively. - Abstract: The objective of this research is flotation separation of polycarbonate (PC) and acrylonitrile–butadiene–styrene (ABS) waste plastics combined with ammonia pretreatment. The PC and ABS plastics show similar hydrophobicity, and ammonia treatment changes selectively floatability of PC plastic while ABS is insensitive to ammonia treatment. The contact angle measurement indicates the dropping of flotation recovery of PC is ascribed to a decline of contact angle. X-ray photoelectron spectroscopy demonstrates reactions occur on PC surface, which makes PC surface more hydrophilic. Separation of PC and ABS waste plastics was conducted based on the flotation behavior of single plastic. At different temperatures, PC and ABS mixtures were separated efficiently through froth flotation with ammonia pretreatment for different time (13 min at 23 °C, 18 min at 18 °C and 30 min at 23 °C). For both PC and ABS, the purity and recovery is more than 95.31% and 95.35%, respectively; the purity of PC and ABS is up to 99.72% and 99.23%, respectively. PC and ABS mixtures with different particle sizes were separated effectively, implying that ammonia treatment possesses superior applicability

  12. Investigating the Inter-Tube Conduction Mechanism in Polycarbonate Nanocomposites Prepared with Conductive Polymer-Coated Carbon Nanotubes

    KAUST Repository

    Ventura, Isaac Aguilar

    2015-12-16

    A well-known strategy to improve the electrical conductivity of polymers is to dope them with high-aspect-ratio and conductive nanoparticles such as carbon nanotubes (CNTs). However, these nanocomposites also exhibit undesirable properties such as damage-sensitive and history-dependent conductivity because their macroscopic electrical conductivity is largely determined by the tunneling effect at the tube/tube interface. To reduce these issues, new nanocomposites have been developed with CNTs that have been coated with a conductive layer of poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOT/PSS). It has been posited that the insulating region between the CNTs is replaced by a conductive polymer bridge; this has not been proven up to now. We propose here to investigate in-depth how the macroscopic conductivity of these materials is changing when (1) varying the frequency of the electrical loading (impedance spectroscopy), (2) varying the mechanical hydrostatic pressure, and (3) varying the voltage of the electrical loading. The response is systematically compared to the one of conventional carbon nanotube/polycarbonate (CNT/PC) nanocomposites so we can clarify how efficiently the tunneling effect is suppressed from these composites. The objective is to elucidate further the mechanism for conduction in such material formulations.

  13. Preparation, mechanical, and in vitro properties of glass fiber-reinforced polycarbonate composites for orthodontic application.

    Science.gov (United States)

    Tanimoto, Yasuhiro; Inami, Toshihiro; Yamaguchi, Masaru; Nishiyama, Norihiro; Kasai, Kazutaka

    2015-05-01

    Generally, orthodontic treatment uses metallic wires made from stainless steel, cobalt-chromium-nickel alloy, β-titanium alloy, and nickel-titanium (Ni-Ti) alloy. However, these wires are not esthetically pleasing and may induce allergic or toxic reactions. To correct these issues, in the present study we developed glass-fiber-reinforced plastic (GFRP) orthodontic wires made from polycarbonate and E-glass fiber by using pultrusion. After fabricating these GFRP round wires with a diameter of 0.45 mm (0.018 inch), we examined their mechanical and in vitro properties. To investigate how the glass-fiber diameter affected their physical properties, we prepared GFRP wires of varying diameters (7 and 13 µm). Both the GFRP with 13-µm fibers (GFRP-13) and GFRP with 7 µm fibers (GFRP-7) were more transparent than the metallic orthodontic wires. Flexural strengths of GFRP-13 and GFRP-7 were 690.3 ± 99.2 and 938.1 ± 95.0 MPa, respectively; flexural moduli of GFRP-13 and GFRP-7 were 25.4 ± 4.9 and 34.7 ± 7.7 GPa, respectively. These flexural properties of the GFRP wires were nearly equivalent to those of available Ni-Ti wires. GFRP-7 had better flexural properties than GFRP-13, indicating that the flexural properties of GFRP increase with decreasing fiber diameter. Using thermocycling, we found no significant change in the flexural properties of the GFRPs after 600 or 1,200 cycles. Using a cytotoxicity detection kit, we found that the glass fiber and polycarbonate components comprising the GFRP were not cytotoxic within the limitations of this study. We expect this metal-free GFRP wire composed of polycarbonate and glass fiber to be useful as an esthetically pleasing alternative to current metallic orthodontic wire. © 2014 Wiley Periodicals, Inc.

  14. Prepare and characterization of nanocomposite - mixed matrix membranes based on polycarbonate

    International Nuclear Information System (INIS)

    Paranhos, Caio M.; Pessan, Luiz A.; Gomes, Ana C. de O.

    2009-01-01

    Mixed matrix membranes based on polycarbonate with different content of sepiolite were prepared by casting. The obtained membranes were characterized by wide-angle X-ray diffraction, thermal analysis, optical transparency and permeation to oxygen. The presence of sepiolite leads to the formation of a polymer-clay interface. The presence of the interface causes the increase in O 2 permeation. Increasing content of sepiolite results in aggregates of sepiolite, which forms preferential channels to the O 2 molecules. This fact is directly related to the strong increasing observed in O 2 permeability. (author)

  15. Simulation of polycarbonate-CNT nanocomposite dosimeter based on electrical characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Malekie, Shahryar; Ziaie, Farhood; Ataee Naeini, Mehran [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Radiation Application Research School

    2016-12-15

    In this research work, the electrical behavior of polycarbonate-carbon nanotube composite, over the radiation absorbed dose under a fixed DC voltage was investigated via finite element method. The predicted electrical percolation threshold value in the composite was validated by experimental results published by other scientists. The absorbed dose value was considered as multiplying of heat capacity and temperature rise of the composite, regarding the calorimetric approach. Results show that this kind of composite can be applied for monitoring and radiation protection utilizations.

  16. Synthesis of optically clear polymeric materials for high temperature windows. [preparation of phenolphthalein polycarbonate resin

    Science.gov (United States)

    Pannell, C. E.; Magner, J. E.

    1973-01-01

    A polymer has been developed that has excellent potential for use as windows in spacecraft as well as conventional aircraft. This polymer, phenolphthalein polycarbonate, has outstanding thermal properties, e.g., in place of melting or burning, it produces an insulating charred foam that closes off transmission of radiant heat through the window. This fact, coupled with an oxygen index of 0.43 and a 177 C tensile strength of 58 mega Newtons/sq m, makes this polymer a prime candidate for further development. Pilot plant preparation in a 20 gallon Pfaudler kettle was accomplished and large test specimens were prepared for evaluations.

  17. Synthesis and Characterization of TiO2 Nanoparticles with Polycarbonate and Investigation of its Mechanical Properties

    Science.gov (United States)

    Jahantigh, Farhad; Nazirzadeh, Mehdi

    In this project, nanocomposite films were prepared with different Titanium dioxide (TiO2) percentages. Properties of polycarbonate (PC) and PC-TiO2 nanocomposite films were studied by X-ray diffraction (XRD) analysis and Fourier transform infrared (FTIR) spectroscopy. The structure of samples was studied by XRD. The mechanical properties of PC-TiO2 nanocomposite films were investigated by conducting tensile tests and hardness measurements. Thermal stability of the nanocomposites was studied by thermogravimetric analysis (TGA) method. The elastic modulus of the composite increased with increasing weight fraction of nanoparticles. The microhardness value increases with increasing TiO2 nanoparticles. The results of tensile testing were in agreement with those of micro-hardness measurements. In addition, TGA curves showed that nanocomposite films have higher resistance to thermal degradation compared to polycarbonate. There are many reports related to the modification of polycarbonate films, but still a systematic study of them is required.

  18. Cs2CO3-promoted polycondensation of CO2with diols and dihalides for the synthesis of miscellaneous polycarbonates

    KAUST Repository

    Chen, Zuliang

    2016-07-12

    A one-pot protocol for the direct synthesis of polycarbonates through polycondensation of diols, dihalides and CO2 in the presence of Cs2CO3 is described. The conditions were optimized by studying the polycondensation of CO2 with 1,4-phenylenedimethanol and 1,4-dibromobutane as model monomers. Then, diols and dihalides with different spacers between the reactive groups including aliphatic, aromatic and poly(ethylene glycol) were tested under optimal conditions. Miscellaneous polycarbonates exhibiting molar masses in the range of 43 000 g mol-1 (GPC) and conversion higher than 96% could be obtained. The proposed mechanism rules out the possibility of ether linkage formation during polycondensation and accounts for the creation of carbonate linkages in two different ways. The thermal properties of the synthesized polycarbonates were unveiled by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). © 2016 The Royal Society of Chemistry.

  19. High energy charged particle registration in CR-39 polycarbonated detector

    International Nuclear Information System (INIS)

    Abdel-Wahab, M.S.; El Enany, N.; El Fiki, S.; Eissa, H.M.; El-Adl, E.H.; El-Feky, M.A.

    1991-01-01

    Track etch rate characteristics of CR-39 plastic detector exposed to 28 Si ions of 670 MeV energy have been investigated. Experimental results were obtained in terms of frequency distribution of the track diameter, track density and bulk etching rate. A dependence of the mean track diameter on energy was found. The application of the radiation effect of heavy ions on CR-39 in the field of radiation detection and dosimetry are discussed. Results indicated that it is possible to produce etchable tracks of 28 Si in this energy range in CR-39. We also report the etching characteristics of these tracks in the CR-39 detector. (orig.) [de

  20. The role of original surface roughness in laser-induced periodic surface structure formation process on poly-carbonate films

    International Nuclear Information System (INIS)

    Csete, M.; Hild, S.; Plettl, A.; Ziemann, P.; Bor, Zs.; Marti, O.

    2004-01-01

    Poly-carbonate films containing different types of original surface roughness were illuminated by a polarized ArF excimer laser beam having a fluence of 4 mJ/cm 2 . Atomic force microscopy was applied to study the laser-induced periodic surface structure formation process at 0 deg. , 30 deg. and 45 deg. angles of incidence. The effect of initial surface structures on the intensity distribution was investigated in cases of: (a) grains on oriented and amorphous thick films; (b) holes on thin spin-coated films; and (c) nanoparticles arranged along micrometer long sides of hexagons below the spin-coated films. The presence of the scattering objects caused symmetry breaking, if the samples were illuminated by oblique incident 's' polarized beam. The Fourier analysis of the AFM pictures has shown the competition of structures having different periods. The characteristic of the permanent surface patterns proved that the interference of the incoming beam and the beams scattered on previously existing structures is the LIPSS generating feedback process. Ring-shaped structures having 228 nm diameter were produced

  1. Region-selective electroless gold plating on polycarbonate sheets by UV-patterning in combination with silver activating

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Qinghua [Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Zijin' gang Campus, Hangzhou 310058 (China); Chen Hengwu, E-mail: hwchen@zju.edu.c [Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Zijin' gang Campus, Hangzhou 310058 (China); Wang Yi [Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Zijin' gang Campus, Hangzhou 310058 (China)

    2010-02-28

    A simple, time- and cost-effective approach for region-selective metalization of polycarbonate (PC) surface has been established by combining photoresist-free UV-patterning with tin- and amine-free silver activating and electroless gold plating. The surface of PC sheets was exposed to the UV lights emitted from a low-pressure mercury lamp through a photomask, the micro pattern on the mask being transferred to the PC surface due to the photochemical generation of carboxyl groups on the UV-exposed region. The UV-exposed PC sheets were then treated with an ammoniacal AgNO{sub 3} solution, so that the silver ions were chemisorbed by the photochemically generated carboxyl groups. When the Ag{sup +}-adsorbed PC sheet was immersed into an electroless gold plating bath, shiny gold film quickly deposited on the UV-exposed region, resulting in the formation of a micro gold devices on the PC surface. The whole plating process including UV-exposure, surface activating and gold plating can be completed in about 3-4 h. Attenuated total reflection Fourier transformation infrared spectrometer (ATR-FT-IR), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and scanning electron microscope (SEM) were employed to trace the surface change during the plating process. Cyclic voltammetry (CV) and Scotch-tape test were employed to characterize the electrochemical properties and adhesion strength of the prepared micro gold devices, respectively. The prepared micro gold electrodes were demonstrated for amperometric detection of hydrogen peroxide.

  2. Influence of Hard Segments on the Thermal, Phase-Separated Morphology, Mechanical, and Biological Properties of Polycarbonate Urethanes

    Directory of Open Access Journals (Sweden)

    Rong Zhu

    2017-03-01

    Full Text Available Abstract: In this study, we have fabricated a series of polycarbonate polyurethanes using a two-step bulk reaction by the melting pre-polymer solution-casting method in order to synthesize biomedical polyurethane elastomers with good mechanical behavior and biostability. The polyurethanes were prepared using dibutyltin dilaurate as the catalyst, poly(1,6-hexanediolcarbonate microdiols (PCDL as the soft segment, and the chain extender 1,4-butanediol (BDO and aliphatic 1,6-hexamethylene diisocyanate (HDI as the hard segments. The chemical structures and physical properties of the obtained films were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR spectroscopy, gel permeation chromatography (GPC, differential scanning calorimeter (DSC, and mechanical property tests. The surface properties and degrees of microphase separation were further analyzed by water droplet contact angle measurements (CA and atomic force microscopy (AFM. The materials exhibited a moderate toxic effect on the tetrazolium (MTT assay and good hemocompatibility through hemolytic tests, indicating a good biocompatibility of the fabricated membranes. The materials could be considered as potential and beneficial suitable materials for tissue engineering, especially in the fields of artificial blood-contacting implants or other biomedical applications.

  3. Separation of polycarbonate and acrylonitrile-butadiene-styrene waste plastics by froth flotation combined with ammonia pretreatment.

    Science.gov (United States)

    Wang, Chong-Qing; Wang, Hui; Liu, Qun; Fu, Jian-Gang; Liu, You-Nian

    2014-12-01

    The objective of this research is flotation separation of polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) waste plastics combined with ammonia pretreatment. The PC and ABS plastics show similar hydrophobicity, and ammonia treatment changes selectively floatability of PC plastic while ABS is insensitive to ammonia treatment. The contact angle measurement indicates the dropping of flotation recovery of PC is ascribed to a decline of contact angle. X-ray photoelectron spectroscopy demonstrates reactions occur on PC surface, which makes PC surface more hydrophilic. Separation of PC and ABS waste plastics was conducted based on the flotation behavior of single plastic. At different temperatures, PC and ABS mixtures were separated efficiently through froth flotation with ammonia pretreatment for different time (13 min at 23 °C, 18 min at 18 °C and 30 min at 23 °C). For both PC and ABS, the purity and recovery is more than 95.31% and 95.35%, respectively; the purity of PC and ABS is up to 99.72% and 99.23%, respectively. PC and ABS mixtures with different particle sizes were separated effectively, implying that ammonia treatment possesses superior applicability. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Temperature- and Angle-Dependent Magnetic Properties of Ni Nanotube Arrays Fabricated by Electrodeposition in Polycarbonate Templates

    Directory of Open Access Journals (Sweden)

    Yonghui Chen

    2016-12-01

    Full Text Available Parallel arrays of Ni nanotubes with an external diameter of 150 nm, a wall thickness of 15 nm, and a length of 1.2 ± 0.3 µm were successfully fabricated in ion-track etched polycarbonate (PC templates by electrochemical deposition. The morphology and crystal structure of the nanotubes were characterized by scanning electron microscopy (SEM, transmission electron microscopy (TEM, and X-ray diffraction (XRD. Structural analyses indicate that Ni nanotubes have a polycrystalline structure with no preferred orientation. Angle dependent hysteresis studies at room temperature carried out by using a vibrating sample magnetometer (VSM demonstrate a transition of magnetization between the two different magnetization reversal modes: curling rotation for small angles and coherent rotation for large angles. Furthermore, temperature dependent magnetic analyses performed with a superconducting quantum interference device (SQUID magnetometer indicate that magnetization of the nanotubes follows modified Bloch’s law in the range 60–300 K, while the deviation of the experimental curve from this law below 60 K can be attributed to the finite size effects in the nanotubes. Finally, it was found that coercivity measured at different temperatures follows Kneller’s law within the premises of Stoner–Wohlfarth model for ferromagnetic nanostructures.

  5. Evaluation of sulphonated polycarbonate membranes for fuel cells; Avaliacao de membranas de policarbonato sulfonado para celulas a combustivel

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Isabela M.M.; Gomes, Ana C.; Pessan, Luiz A. [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Engenharia de Materiais], e-mail: isabelamuglia@gmail.com; Paranhos, Caio [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Quimica

    2011-07-01

    Fuel cells based on ion conducting polymer membranes offer an alternative for the conventional energetic matrices. Among many advantages of this system, we can mention the reduction on the emission of pollutants, high efficiency and simplicity. This work presents the modification of polycarbonate by sulfonation reaction using acetyl sulfate, in order to increase the conductor ionic character of the membranes used as electrolytes for hydrogen fuel cells. The sulfonated polycarbonate membranes were obtained by casting and then characterized by Fourier transform infrared spectroscopy, water vapor transmission, differential scanning calorimetry, thermogravimetric analysis and viscosimetry. (author)

  6. Melt crystallization of bisphenol A polycarbonate in PC/zinc sulfonated polystyrene ionomer blend

    Science.gov (United States)

    Xu, Liang

    The effects of zinc sulfonated polystyrene ionomer (ZnSPS) on the melt crystallization of bisphenol A polycarbonate (PC) were investigated. Melt crystallization of pure PC is extremely slow due to its rigid chain. In the blend of PC and ZnSPS (PC-ZnSPS), the melt crystallization rate of PC can be enhanced. DSC was used to study the crystallization kinetics of PC in PC-ZnSPS blend. The crystallization of PC at 190°C increased in both partially miscible and miscible blends with ZnSPS. For PC-ZnSPS blend with same PC composition as 80%, the crystallization rate was affected by the sulfonation level of ZnSPS. The induction time of crystallization for a partially miscible blend PC-ZnSPS9.98 (80/20) was 40 minutes, and the crystallization reaches 27% crystallinity within 14 hrs. The induction time for pure PC with the same thermal history was more than 24 hrs. The crystal structure of PC crystal formed in PC-ZnSPS blend was studied by WAXD, which showed no difference from the reported WAXD pattern for pure PC. Molecular weight change of PC was found during the thermal annealing of PC-ZnSPS blend at 190°C, but molecular weight alone cannot explain the change of crystallization rate of PC in PC-ZnSPS blend. Discussion was made to address the mechanisms that are responsible for the crystallization rate enhancement of PC in PC-ZnSPS blend. In order to understand and elucidate the reason for the molecular weight change of PC in PC-ZnSPS blend and its effect on the crystallization of PC, TG, GPC and GC-MS were used to investigate the stability of PC-ZnSPS blend and mixtures of PC with sodium tosylate (NaTS), zinc tosylate (ZnTS) and sodium benzoate (NaBZ). ZnSPS, NaTS and ZnTS undergo desulfonation of the sulfonate group at temperatures above 350°C. The desulfonation process can destabilize PC and lower the maximum mass loss rate temperature of PC for more than 70°C. NaTS, ZnTS and NaBZ have quite different effect on the thermal stability of PC at temperatures below 250

  7. Low Loss Polycarbonate Polymer Optical Fiber for High Temperature FBG Humidity Sensing

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Fasano, Andrea; Markos, Christos

    2017-01-01

    We report the fabrication and characterization of a polycarbonate (PC) microstructured polymer optical fiber (mPOF) Bragg grating (FBG) humidity sensor that can operate beyond 100°C. The PC preform, from which the fiber was drawn, was produced using an improved casting approach to reduce the atte......We report the fabrication and characterization of a polycarbonate (PC) microstructured polymer optical fiber (mPOF) Bragg grating (FBG) humidity sensor that can operate beyond 100°C. The PC preform, from which the fiber was drawn, was produced using an improved casting approach to reduce...... the attenuation of the fiber. The fiber loss was found reduced by a factor of two compared to the latest reported PC mPOF [20], holding the low loss record in PC based fibers. PC mPOFBG was characterized to humidity and temperature, and a relative humidity (RH) sensitivity of 7.31± 0.13 pm/% RH in the range 10...

  8. Standard Test Method for Impact Resistance of Monolithic Polycarbonate Sheet by Means of a Falling Weight

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1995-01-01

    1.1 This test method covers the determination of the energy required to initiate failure in monolithic polycarbonate sheet material under specified conditions of impact using a free falling weight. 1.2 Two specimen types are defined as follows: 1.2.1 Type A consists of a flat plate test specimen and employs a clamped ring support. 1.2.2 Type B consists of a simply supported three-point loaded beam specimen (Fig. 1) and is recommended for use with material which can not be failed using the Type A specimen. For a maximum drop height of 6.096 m (20 ft) and a maximum drop weight of 22.68 kg (50 lb), virgin polycarbonate greater than 12.70 mm (1/2 in.) thick will probably require use of the Type B specimen. Note 1 - See also ASTM Methods: D 1709, D 2444 and D 3029. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of reg...

  9. Experimental and Numerical Investigation of Perforation of Thin Polycarbonate Plate by Projectiles of Different Nose Shape

    Directory of Open Access Journals (Sweden)

    Afsar Husain

    Full Text Available Abstract The present study is based on experimental investigation and numerical simulation of impact of different nose shape projectiles on thin polycarbonate plates. Rigid hardened projectiles of two different geometries (Blunt and Truncated cone keeping the same shank diameter and total mass were prepared. These projectiles were impacted through pneumatic gun setup on circular polycarbonate plates at varying impact velocities upto 106 m/s. Impact and residual velocities were measured before and after perforation, respectively. Numerical simulations were performed in ABAQUS/EXPLICIT finite element code. The problem has been modelled based on Mie-Gruneisen equation of state. The experimental results obtained in terms of ballistic limit, residual velocity, energy absorbed and deformation mechanism have been compared with the numerical results and are found to be in excellent agreement. It is observed that the ballistic limit for normal impact is greater for blunt projectile compared to truncated conical projectile. Velocity drop and the energy absorbed is higher for blunt projectile compared to truncated conical projectiles for the impact velocities under study.

  10. Theoretical studies on thermal degradation reaction mechanism of model compound of bisphenol A polycarbonate.

    Science.gov (United States)

    Huang, Jinbao; He, Chao; Li, Xinsheng; Pan, Guiying; Tong, Hong

    2018-01-01

    Density functional theory methods (DFT) M062X have been used to investigate the thermal degradation processes of model compound of bisphenol A polycarbonate (MPC) and to identify the optimal reaction paths in the thermal decomposition of bisphenol A polycarbonate (PC). The bond dissociation energies of main bonds in MPC were calculated, and it is found that the weakest bond in MPC is the single bond between the methylic carbon and carbon atom and the second weakest bond in MPC is the single bond between oxygen atom and the carbonyl carbon. On the basis of computational results of kinetic parameters, a mechanism is proposed where the hydrolysis (or alcoholysis) reaction is the main degradation pathways for the formation of the evolved products, and the homolytic cleavage and rearrangement reactions are the competitive reaction pathways in the thermal degradation of PC. The proposed mechanism is consistent with experimental observations of CO 2 , bisphenol A and 1,1-bis(4-hydroxyphenyl)-ethane as the main degradation products, together with a small amount of CO, alkyl phenol and diphenyl carbonate. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Polycarbonate activation for electroless plating by dimethylaminoborane absorption and subsequent nanoparticle deposition

    Science.gov (United States)

    Muench, Falk; Bohn, Sebastian; Rauber, Markus; Seidl, Tim; Radetinac, Aldin; Kunz, Ulrike; Lauterbach, Stefan; Kleebe, Hans-Joachim; Trautmann, Christina; Ensinger, Wolfgang

    2014-07-01

    Electroless plating of metal films on polymer substrates usually requires the presence of metal particles acting as catalytically active nuclei for the deposition reaction. Herein, we present a novel and versatile approach towards the activation of polycarbonate substrates with metal nanoparticles. It is based on the diffusion of dimethylaminoborane into the polymer matrix, followed by reaction of the sensitized substrates with metal salt solutions. The reducing agent uptake was controlled by changing the duration of the sensitization and the dimethylaminoborane concentration in the sensitization solution. Different seed types (Ag, Au, Pd, Pt and Rh) were deposited by variation of the activation solution. The proposed mechanism was confirmed with FTIR and TEM measurements. In addition, AFM revealed that apart from a slight roughening in the nanometer range, the surface morphology of the polymer remained unchanged, rendering the method viable for template-based nanomaterial fabrication. Due to its pronounced variability, the new technique allows to tailor the activity of polymer substrates for consecutive electroless plating. The feasibility and nanoscale homogeneity of the process were proven by the electroless fabrication of well-defined Au and Pt nanotubes in ion-track etched polycarbonate templates. The combination of features (use of simple and easily scalable wet-chemical processes, facile seed variation, high activation quality on complex surfaces) renders the outlined technique promising for the fabrication of intricate nanomaterials as well as for the metallization of macroscopic work pieces.

  12. Attractive mechanical properties of a lightweight highly sensitive bi layer thermistor: polycarbonate/organic molecular conductor

    International Nuclear Information System (INIS)

    Laukhina, E; Lebedev, V; Rovira, C; Laukhin, V; Veciana, J

    2016-01-01

    The paper covers some of the basic mechanical characteristics of a recently developed bi layer thermistor: polycarbonate/(001) oriented layer of organic molecular conductor α’-(BEDT-TTF) 2 I x Br 3-x , were BEDT-TTF=bis(ethylenedithio)tetrathiafulvalen. The nano and macro mechanical properties have been studied in order to use this flexible, low cost thermistor in sensing applications by proper way. The nano-mechanical properties of the temperature sensitive semiconducting layer of α’-(BEDT-TTF) 2 I x Br 3-x were tested using nanoindentation method. The value of Young's modulus in direction being perpendicular to the layer plan was found as 9.0 ±1.4 GPa. The macro mechanical properties of the thermistor were studied using a 5848 MicroTester. The tensile tests showed that basic mechanical characteristics of the thermistor are close to those of polycarbonate films. This indicates a good mechanical strength of the developed sensor. Therefore, the thermistor can be used in technologies that need to be instrumented with highly robustness lightweight low cost temperature sensors. The paper also reports synthetic details on fabricating temperature sensing e-textile. As the temperature control is becoming more and more important in biomedical technologies like healthcare monitoring, this work strongly contributes on the ongoing research on engineering sensitive conducting materials for biomedical applications. (paper)

  13. Helium ion distributions in a 4 kJ plasma focus device by 1 mm-thick large-size polycarbonate detectors

    Science.gov (United States)

    Sohrabi, M.; Habibi, M.; Ramezani, V.

    2014-11-01

    Helium ion beam profile, angular and iso-ion beam distributions in 4 kJ Amirkabir plasma focus (APF) device were effectively observed by the unaided eyes and studied in single 1 mm-thick large-diameter (20 cm) polycarbonate track detectors (PCTD). The PCTDs were processed by 50 Hz-HV electrochemical etching using a large-size ECE chamber. The results show that helium ions produced in the APF device have a ring-shaped angular distribution peaked at an angle of ∼ ± 60 ° with respect to the top of the anode. Some information on the helium ion energy and distributions is also provided. The method is highly effective for ion beam studies.

  14. Novel routes in flame retardancy of bisphenol A polycarbonate/impact modifier/aryl phosphate blends

    Energy Technology Data Exchange (ETDEWEB)

    Wawrzyn, Eliza

    2013-07-01

    The massive use of electronic engineering products accompanied by high demands on fire safety has led to increasing interest in environmentally friendly flame retardancy of bisphenol A polycarbonate (PC) based materials. In this work, novel routes for enhancing the flame retardancy of PC/Impact Modifier/Aryl phosphate were studied with respect to pyrolysis (TG, TG-FTIR, ATR-FTIR, NMR), flammability (LOI and UL 94) and fire behavior (cone calorimeter at different irradiations). To improve charring of PC/ABS{sub PTFE}+Aryl phosphate, the exchange of bisphenol A bis(diphenyl phosphate) (BDP) with novel aryl phosphates was proposed. Two novel flame retardants were synthesized: 3,3,5-trimethylcyclohexylbisphenol-bis(diphenyl phosphate) (TMC-BDP) and bisphenol A-bis(diethylphosphate) (BEP). TMC-BDP was more stable than BDP, thus gave a potential to increase the chemical reactions between the components of the PC/ABS{sub PTFE}+Aryl phosphate, whereas more reactive BEP was expected to increase the cross linking activity with the polymer matrix. Nevertheless, the corresponding blends did not enhance the flame retardancy compared to PC/ABS{sub PTFE}+BDP. BEP in PC/ABS{sub PTFE} preferred to cross-link with itself instead of with PC, thus it showed poor fire protection performance. TMC-BDP gave as good results as BDP in PC/ABS PTFE material. The results delivered evidence that BDP possesses a high degree of optimization in PC/ABS{sub PTFE} system. To provide a novel impact modifier improving not only mechanical properties but also the fire retardancy of PC/BDP material, the replacement of highly flammable acrylonitrile-butadiene-styrene (ABS) with silicon acrylate rubber (SiR) with high content of polydimethylsiloxane (PDMS) was studied. In PC/SiR{sub PTFE}/BDP the replacement of ABS is beneficial, but PDMS worsened the BDP gas phase and condensed phase action. PDMS reacted also with PC during combustion. PDMS-PC and PDMS-BDP interactions led to silicon dioxide. In fact, the

  15. The influence of organoclays on the morphology, phase separation and thermal properties of polycarbonate-based polyurethane hybrid materials

    Czech Academy of Sciences Publication Activity Database

    Pavličević, J.; Špírková, Milena; Sinadinović-Fišer, S.; Budinski-Simendic, J.; Govedarica, O.; Janković, M.

    2013-01-01

    Roč. 32, č. 1 (2013), s. 151-161 ISSN 1857-5552 R&D Projects: GA ČR GAP108/10/0195 Institutional support: RVO:61389013 Keywords : polycarbonate-based polyurethane * bentonite * montmorillonite Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.310, year: 2013 http://www.mjcce.org.mk/index.php/MJCCE/article/view/144

  16. Fabrication and characterization of polycarbonate microstructured polymer optical fibers for high-temperature-resistant fiber Bragg grating strain sensors

    DEFF Research Database (Denmark)

    Fasano, Andrea; Woyessa, Getinet; Stajanca, Pavol

    2016-01-01

    Here we present the fabrication of a solid-core microstructured polymer optical fiber (mPOF) made of polycarbonate (PC), and report the first experimental demonstration of a fiber Bragg grating (FBG) written in a PC optical fiber. The PC used in this work has a glass transition temperature of 145°C...

  17. Mechanical, thermal and morphological characterization of polycarbonate/oxidized carbon nanofiber composites produced with a lean 2-step manufacturing process.

    Science.gov (United States)

    Lively, Brooks; Kumar, Sandeep; Tian, Liu; Li, Bin; Zhong, Wei-Hong

    2011-05-01

    In this study we report the advantages of a 2-step method that incorporates an additional process pre-conditioning step for rapid and precise blending of the constituents prior to the commonly used melt compounding method for preparing polycarbonate/oxidized carbon nanofiber composites. This additional step (equivalent to a manufacturing cell) involves the formation of a highly concentrated solid nano-nectar of polycarbonate/carbon nanofiber composite using a solution mixing process followed by melt mixing with pure polycarbonate. This combined method yields excellent dispersion and improved mechanical and thermal properties as compared to the 1-step melt mixing method. The test results indicated that inclusion of carbon nanofibers into composites via the 2-step method resulted in dramatically reduced ( 48% lower) coefficient of thermal expansion compared to that of pure polycarbonate and 30% lower than that from the 1-step processing, at the same loading of 1.0 wt%. Improvements were also found in dynamic mechanical analysis and flexural mechanical properties. The 2-step approach is more precise and leads to better dispersion, higher quality, consistency, and improved performance in critical application areas. It is also consistent with Lean Manufacturing principles in which manufacturing cells are linked together using less of the key resources and creates a smoother production flow. Therefore, this 2-step process can be more attractive for industry.

  18. A novel process for separation of polycarbonate, polyvinyl chloride and polymethyl methacrylate waste plastics by froth flotation.

    Science.gov (United States)

    Wang, Chong-Qing; Wang, Hui; Huang, Luo-Luo

    2017-07-01

    A novel process was proposed for separation of ternary waste plastics by froth flotation. Pretreatment of plastics with potassium permanganate (KMnO 4 ) solution was conducted to aid flotation separation of polycarbonate (PC), polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA) plastics. The effect of pretreatment parameters including KMnO 4 concentration, treatment time, temperature and stirring rate on flotation recovery were investigated by single factor experiments. Surface treatment with KMnO 4 changes selectively the flotation behavior of PC, PVC and PMMA, enabling separation of the plastics by froth flotation. Mechanism of surface treatment was studied by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectrum (XPS). Effect of frother concentration and flotation time on flotation behavior of plastic mixtures was further studied for flotation separation. The optimized conditions for separation of PC are KMnO 4 concentration 2mmolL -1 , treatment time 10min, temperature 60°C, stirring rate 300rpm, flotation time 1min and frother concentration 17.5mgL -1 . Under optimum conditions, PVC and PMMA mixtures are also separated efficiently by froth flotation associated with KMnO 4 treatment. The purity of PC, PVC and PMMA is up to 100%, 98.41% and 98.68%, while the recovery reaches 96.82%, 98.71% and 98.38%, respectively. Economic analysis manifests remarkable profits of the developed process. Reusing KMnO 4 solution is feasible, enabling the process greener. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Morphology, Nucleation, and Isothermal Crystallization Kinetics of Poly(Butylene Succinate Mixed with a Polycarbonate/MWCNT Masterbatch

    Directory of Open Access Journals (Sweden)

    Thandi P. Gumede

    2018-04-01

    Full Text Available In this study, nanocomposites were prepared by melt blending poly(butylene succinate (PBS with a polycarbonate (PC/multi-wall carbon nanotubes (MWCNTs masterbatch, in a twin-screw extruder. The nanocomposites contained 0.5, 1.0, 2.0, and 4.0 wt% MWCNTs. Differential scanning calorimetry (DSC, small angle X-ray scattering (SAXS and wide angle X-ray scattering (WAXS results indicate that the blends are partially miscible, hence they form two phases (i.e., PC-rich and PBS-rich phases. The PC-rich phase contained a small amount of PBS chains that acted as a plasticizer and enabled crystallization of the PC component. In the PBS-rich phase, the amount of the PC chains present gave rise to increases in the glass transition temperature of the PBS phase. The presence of two phases was supported by scanning electron microscopy (SEM and atomic force microscopy (AFM analysis, where most MWCNTs aggregated in the PC-rich phase (especially at the high MWCNTs content of 4 wt% and a small amount of MWCNTs were able to diffuse to the PBS-rich phase. Standard DSC scans showed that the MWCNTs nucleation effects saturated at 0.5 wt% MWCNT content on the PBS-rich phase, above this content a negative nucleation effect was observed. Isothermal crystallization results indicated that with 0.5 wt% MWCNTs the crystallization rate was accelerated, but further increases in MWCNTs loading (and also in PC content resulted in progressive decreases in crystallization rate. The results are explained by increased MWCNTs aggregation and reduced diffusion rates of PBS chains, as the masterbatch content in the blends increased.

  20. Evaluation of physico-chemical properties of electron beam-irradiated polycarbonate film

    Science.gov (United States)

    Jaleh, B.; Parvin, P.; Sheikh, N.; Ziaie, F.; Haghshenas, M.; Bozorg, L.

    2007-11-01

    In this work, polycarbonate (PC) film samples were irradiated with 10 MeV electrons at different doses ranging from 25 to 250 kGy. Characterization techniques viz. thermogravimetric analysis (TGA), Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction analysis (XRD) and electron paramagnetic resonance (EPR) were exploited to understand the induced changes in the physico-chemical properties of the polymer. An increase in the decomposition temperature with increasing dose was observed, while the crystallinity remained unchanged as a result of the formation of cross-link bond. EPR technique characterized the stability of the free radicals in the irradiated PC. The result showed that cross-linking process occurs at low absorbed doses, whereas polymer degradation happens at higher doses.

  1. Polycarbonate crowns for primary teeth revisited: restorative options, technique and case reports.

    Science.gov (United States)

    Venkataraghavan, Karthik; Chan, John; Karthik, Sandhya

    2014-01-01

    Esthetics by definition is the science of beauty - that particular detail of an animate or inanimate object that makes it appealing to the eye. In the modern, civilized, and cosmetically conscious world, well-contoured and well-aligned white teeth set the standard for beauty. Such teeth are not only considered attractive but are also indicative of nutritional health, self esteem, hygienic pride, and economic status. Numerous treatment approaches have been proposed to address the esthetics and retention of restorations in primary teeth. Even though researchers have claimed that certain restorations are better than the others, particularly owing to the issues mentioned above, the search for the ideal esthetic restoration for the primary teeth continues. This paper revisits and attempts to reintroduce the full coverage restoration, namely, polycarbonate crown, for use in primary anterior teeth.

  2. Polycarbonate crowns for primary teeth revisited: Restorative options, technique and case reports

    Directory of Open Access Journals (Sweden)

    Karthik Venkataraghavan

    2014-01-01

    Full Text Available Esthetics by definition is the science of beauty - that particular detail of an animate or inanimate object that makes it appealing to the eye. In the modern, civilized, and cosmetically conscious world, well-contoured and well-aligned white teeth set the standard for beauty. Such teeth are not only considered attractive but are also indicative of nutritional health, self esteem, hygienic pride, and economic status. Numerous treatment approaches have been proposed to address the esthetics and retention of restorations in primary teeth. Even though researchers have claimed that certain restorations are better than the others, particularly owing to the issues mentioned above, the search for the ideal esthetic restoration for the primary teeth continues. This paper revisits and attempts to reintroduce the full coverage restoration, namely, polycarbonate crown, for use in primary anterior teeth.

  3. ECE laboratory in the Vinca Institute - its basic characteristics and fundamentals of electrochemical etching on polycarbonate

    International Nuclear Information System (INIS)

    Zunic, Z.S.; Ujic, P.; Celikovic, I.; Fujimoto, K.

    2003-01-01

    This paper deals with the introductory aspects of the Electrochemical Etching Laboratory installed at the VINCA Institute in the year 2003. The main purpose of the laboratory is its field application for radon and thoron large-scale survey using passive radon/thoron UFO type detectors. Since the etching techniques together with the laboratory equipment were transferred from the National Institute of Radiological Sciences, Chiba, Japan, it was necessary for both etching conditions to be confirmed and to be checked up, i. e., bulk etching speeds of chemical etching and electrochemical etching in the VINCA Electrochemical Etching Laboratory itself. Beside this initial step, other concerns were taken into consideration in this preliminary experimental phase such as the following: the measurable energy range of the polycarbonate film, background etch pit density of the film and its standard deviation and reproducibility of the response to alpha particles for different sets of etchings. (author)

  4. Design Concepts of Polycarbonate-Based Intervertebral Lumbar Cages: Finite Element Analysis and Compression Testing

    Directory of Open Access Journals (Sweden)

    J. Obedt Figueroa-Cavazos

    2016-01-01

    Full Text Available This work explores the viability of 3D printed intervertebral lumbar cages based on biocompatible polycarbonate (PC-ISO® material. Several design concepts are proposed for the generation of patient-specific intervertebral lumbar cages. The 3D printed material achieved compressive yield strength of 55 MPa under a specific combination of manufacturing parameters. The literature recommends a reference load of 4,000 N for design of intervertebral lumbar cages. Under compression testing conditions, the proposed design concepts withstand between 7,500 and 10,000 N of load before showing yielding. Although some stress concentration regions were found during analysis, the overall viability of the proposed design concepts was validated.

  5. Measurement of low neutron fluences with polycarbonate foils electrochemically etched with methyl alcohol-KOH solution

    International Nuclear Information System (INIS)

    Kumamoto, Y.

    1982-01-01

    Electrochemical etching of polycarbonate foils was performed using a KOH solution with a high concentration of methyl alcohol under different conditions of field strength, frequency, temperature and etching time. These studies showed that the highest neutron sensitivity relative to the inherent background in the foil was obtained under the following etching conditions: 52 kV/cm, 1 kHz, 30 0 C, 30 min in a solution of 45 gm KOH + 80 cc CH 3 OH + 20 cc H 2 O. Under these conditions, 100 mrem of neutrons from a Ra-Be source gave 70 pits per cm 2 while background was 7 +- 3 pits per cm 2 (10 +- 5 mrem). The pit diameters were about 90 μm. This sensitivity (giving lowest measurable dose of 15 mrem) is quite sufficient for personnel neutron dosimetry applications and the size of the pits is large enough for easy counting using a microscope at magnification of 40X. (author)

  6. Production and Characterization of Polycarbonate Microstructured Polymer Optical Fiber Bragg Grating Sensor

    DEFF Research Database (Denmark)

    Fasano, Andrea; Woyessa, Getinet; Stajanca, P.

    2015-01-01

    We present the fabrication and characterization of a polycarbonate (PC) microstructured polymer optical fiber (mPOF) and the writing of a fiber Bragg grating (FBG) in it to obtain a polymer optical FBG sen-sor. The manufacturing process of the PC mPOF consists of multiple consecutive stages...... and strain sensing. The PC optical fibers are for some applications an attractive alternative to conventional materials used in POF fabrication, such as polymethyl methacrylate (PMMA). In general, PC can be used at temperature up to 120 °C and breaks at considerably higher strains than PMMA......., such as casting of pol-ymer granulates into a solid rod, machining and drilling of a 3-ring hexagonal lattice of holes into it, and finally drawing into fiber. We demonstrate that the obtained PC mPOF is photosensitive and FBGs can be conveniently inscribed into it, thereby enabling FBG-based temperature...

  7. Pyrolysis and catalytic pyrolysis as a recycling method of waste CDs originating from polycarbonate and HIPS.

    Science.gov (United States)

    Antonakou, E V; Kalogiannis, K G; Stephanidis, S D; Triantafyllidis, K S; Lappas, A A; Achilias, D S

    2014-12-01

    Pyrolysis appears to be a promising recycling process since it could convert the disposed polymers to hydrocarbon based fuels or various useful chemicals. In the current study, two model polymers found in WEEEs, namely polycarbonate (PC) and high impact polystyrene (HIPS) and their counterparts found in waste commercial Compact Discs (CDs) were pyrolysed in a bench scale reactor. Both, thermal pyrolysis and pyrolysis in the presence of two catalytic materials (basic MgO and acidic ZSM-5 zeolite) was performed for all four types of polymers. Results have shown significant recovery of the monomers and valuable chemicals (phenols in the case of PC and aromatic hydrocarbons in the case of HIPS), while catalysts seem to decrease the selectivity towards the monomers and enhance the selectivity towards other desirable compounds. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Nanopore detection of double stranded DNA using a track-etched polycarbonate membrane.

    Science.gov (United States)

    Kececi, Kaan; San, Nevim; Kaya, Dila

    2015-11-01

    We investigate the resistive-pulse sensing of 50-bp DNA using track-etched polycarbonate (PC) nanopores and show the translocation dynamics originating from the electrophoretic transport of DNAs. Conically shaped PC nanopore membranes have been prepared with asymmetric chemical etching technique. We show the potential and concentration dependence of DNA translocation through a PC nanopore. We find that the translocation of DNA scales linearly with both potential and concentration. Additionally, the threshold potential is determined to complete the translocation. Finally, by investigating the current-pulse amplitudes of nanopores with different tip sizes, we show that the nanopore size can be successfully used to distinguish the DNA molecules. These results suggest great promise for the sensing of short DNAs and understanding the dynamics of the translocation process using chemically-etched PC nanopores. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Improving electrical conductivity in polycarbonate nanocomposites using highly conductive PEDOT/PSS coated MWCNTs

    KAUST Repository

    Zhou, Jian

    2013-07-10

    We describe a strategy to design highly electrically conductive polycarbonate nanocomposites by using multiwalled carbon nanotubes (MWCNTs) coated with a thin layer of poly(3,4-ethylenedioxythiophene)/ poly(styrenesulfonate), a conductive polymer. We found that this coating method improves the electrical properties of the nanocomposites in two ways. First, the coating becomes the main electrical conductive path. Second, the coating promotes the formation of a percolation network at a low filler concentration (0.3 wt %). To tailor the electrical properties of the conductive polymer coating, we used a polar solvent ethylene glycol, and we can tune the final properties of the nanocomposite by controlling the concentrations of the elementary constituents or the intrinsic properties of the conductive polymer coating. This very flexible technique allows for tailoring the properties of the final product. © 2013 American Chemical Society.

  10. Assessment of the viscoelastic mechanical properties of polycarbonate urethane for medical devices.

    Science.gov (United States)

    Beckmann, Agnes; Heider, Yousef; Stoffel, Marcus; Markert, Bernd

    2018-03-09

    The underlying research work introduces a study of the mechanical properties of polycarbonate urethane (PCU), used in the construction of various medical devices. This comprises the discussion of a suitable material model, the application of elemental experiments to identify the related parameters and the numerical simulation of the applied experiments in order to calibrate and validate the mathematical model. In particular, the model of choice for the simulation of PCU response is the non-linear viscoelastic Bergström-Boyce material model, applied in the finite-element (FE) package Abaqus®. For the parameter identification, uniaxial tension and unconfined compression tests under in-laboratory physiological conditions were carried out. The geometry of the samples together with the applied loadings were simulated in Abaqus®, to insure the suitability of the modelling approach. The obtained parameters show a very good agreement between the numerical and the experimental results. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Mercuric iodide composite films using polyamide, polycarbonate and polystyrene fabricated by casting

    International Nuclear Information System (INIS)

    Ugucioni, J.C.; Ghilardi Netto, T.; Mulato, M.

    2010-01-01

    Mercuric iodide (HgI 2 ) composite films were obtained by using the casting technique. Insulator polymers such as polyamide, polycarbonate and polystyrene were mixed to HgI 2 crystallites forming a final sub-millimeter thick self-standing film. Fabrication temperature varied from 10 to 100 o C, and total fabrication time reached at most 5 min. The larger the fabrication temperature, the thinner the film and the smaller its electrical resistivity. Electrical characterization was performed in the dark, under UV illumination and under mammographic X-ray exposure. The final properties of the films are discussed and related to fabrication conditions. The optimized composite film might be a better candidate for use as X-ray detector for medical imaging, in place of the single HgI 2 crystalline device.

  12. Grafting of phosphorylcholine functional groups on polycarbonate urethane surface for resisting platelet adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bin [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@hotmail.com [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China); Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Lu, Jian; Zhang, Li; Zhao, Miao; Shi, Changcan; Khan, Musammir [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Guo, Jintang [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China)

    2013-07-01

    In order to improve the resistance of platelet adhesion on material surface, 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted onto polycarbonate urethane (PCU) surface via Michael reaction to create biomimetic structure. After introducing primary amine groups via coupling tris(2-aminoethyl)amine (TAEA) onto the polymer surface, the double bond of MPC reacted with the amino group to obtain MPC modified PCU. The modified surface was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results verified that MPC was grafted onto PCU surface by Michael reaction method. The MPC grafted PCU surface had a low water contact angle and a high water uptake. This means that the hydrophilic PC functional groups improved the surface hydrophilicity significantly. In addition, surface morphology of MPC grafted PCU film was imaged by atomic force microscope (AFM). The results showed that the grafted surface was rougher than the blank PCU surface. In addition, platelet adhesion study was evaluated by scanning electron microscopy (SEM) observation. The PCU films after treated with platelet-rich plasma demonstrated that much fewer platelets adhered to the MPC-grafted PCU surface than to the blank PCU surface. The antithrombogenicity of the MPC-grafted PCU surface was determined by the activated partial thromboplastin time (APTT). The result suggested that the MPC modified PCU may have potential application as biomaterials in blood-contacting and some subcutaneously implanted devices. - Highlights: • MPC was successfully grafted onto polycarbonate urethane surface via Michael reaction. • High concentration of PC functional groups on the surface via TAEA molecule • Biomimetic surface modification • The modified surface showed high hydrophilicity and anti-platelet adhesion.

  13. Hyperspectral chemical imaging reveals spatially varied degradation of polycarbonate urethane (PCU) biomaterials.

    Science.gov (United States)

    Dorrepaal, Ronan M; Lawless, Bernard M; Burton, Hanna E; Espino, Daniel M; Shepherd, Duncan E T; Gowen, Aoife A

    2018-04-04

    Hyperspectral chemical imaging (HCI) is an emerging technique which combines spectroscopy with imaging. Unlike traditional point spectroscopy, which is used in the majority of polymer biomaterial degradation studies, HCI enables the acquisition of spatially localised spectra across the surface of a material in an objective manner. Here, we demonstrate that attenuated total reflectance Fourier transform infra-red (ATR-FTIR) HCI reveals spatial variation in the degradation of implantable polycarbonate urethane (PCU) biomaterials. It is also shown that HCI can detect possible defects in biomaterial formulation or specimen production; these spatially resolved images reveal regional or scattered spatial heterogeneity. Further, we demonstrate a map sampling method, which can be used in time-sensitive scenarios, allowing for the investigation of degradation across a larger component or component area. Unlike imaging, mapping does not produce a contiguous image, yet grants an insight into the spatial heterogeneity of the biomaterial across a larger area. These novel applications of HCI demonstrate its ability to assist in the detection of defective manufacturing components and lead to a deeper understanding of how a biomaterial's chemical structure changes due to implantation. Statement of Signifance The human body is an aggressive environment for implantable devices and their biomaterial components. Polycarbonate urethane (PCU) biomaterials in particular were investigated in this study. Traditionally one or a few points on the PCU surface are analysed using ATR-FTIR spectroscopy. However the selection of acquisition points is susceptible to operator bias and critical information can be lost. This study utilises hyperspectral chemical imaging (HCI) to demonstrate that the degradation of a biomaterial varies spatially. Further, HCI revealed spatial variations of biomaterials that were not subjected to oxidative degradation leading to the possibility of HCI being used in the

  14. Fabrication and Characterization of Polycarbonate Polyurethane (PCPU) Nanofibers Impregnated with Nanofillers

    Science.gov (United States)

    Katakam, Hruday chand

    Polycarbonate polyurethane (PCPU) has been studied as a novel polymer impregnated with nanoparticles for improved mechanical, thermal and adhesion properties. This study investigates the synthesis of polycarbonate polyurethane (PCPU) polymeric nanofiber membranes by the process of electrospinning. This study further examines all the parameters associated with electrospinning a novel PCPU polymeric solution impregnated with nanofillers, such as nanoparticles, to produce fiber membranes. Tetrahydrofuran (THF) and N, N dimethylformamide (DMF) are used as solvents to dissolve PCPU polymer. One percent (1%) of nanofillers like silver and silica nanoparticles are added to PCPU polymer solution to investigate the impact on polymer solution properties, which in turn affects the fiber formation. Process parameters are studied by evaluating the impact each parameter has on the fiber formation. PCPU polymer concentrations of three polymer solutions (PCPU, PCPU + 1% silver and PCPU + 1% silica) with the appropriate solvent mixture ratio are achieved to produce polymeric fiber membranes with minimal bead formation. Polymeric nanofiber membranes of PCPU, PCPU + 1% silver and PCPU + 1% silica are produced using THF/DMF: 70/30 (V/V) solvent mixture. The polymeric nanofiber membranes obtained are characterized by using a scanning electron microscopy, rotational viscometer, tensiometer, contact angle measurement device, fourier transform infrared spectroscopy (FTIR). A comparative life cycle assessment (LCA) is performed to evaluate environmental impacts associated with solvents in the process of producing PCPU polymeric nanofiber membranes. The LCA is completed to gauge the potential impacts PCPU nanofiber membranes may have when utilized for various applications. This study discusses the successful production and characterization of good quality (no beading) polymeric nanofiber membranes of PCPU and novel composites of PCPU + 1% silver and PCPU + 1% silica. This two dimensional

  15. Assessment of polycarbonate filter in a molecular analytical system for the microbiological quality monitoring of recycled waters onboard ISS.

    Science.gov (United States)

    Bechy-Loizeau, Anne-Laure; Flandrois, Jean-Pierre; Abaibou, Hafid

    2015-07-01

    On the ISS, as on Earth, water is an essential element for life and its quality control on a regular basis allows to ensure the health of the crew and the integrity of equipment. Currently, microbial water analysis onboard ISS still relies on the traditional culture-based microbiology methods. Molecular methods based on the amplification of nucleic acids for microbiological analysis of water quality show enormous potential and are considered as the best alternative to culture-based methods. For this reason, the Midass, a fully integrated and automated prototype was designed conjointly by ESA and bioMérieux for a rapid monitoring of the microbiological quality of air. The prototype allows air sampling, sample processing and the amplification/detection of nucleic acids. We describe herein the proof of principle of an analytical approach based on molecular biology that could fulfill the ESA's need for a rapid monitoring of the microbiological quality of recycled water onboard ISS. Both concentration and recovery of microorganisms are the main critical steps when the microfiltration technology is used for water analysis. Among filters recommended standards for monitoring the microbiological quality of the water, the polycarbonate filter was fully in line with the requirements of the ISO 7704-1985 standard in terms of efficacy of capture and recovery of bacteria. Moreover, this filter does not retain nucleic acids on the surface and has no inhibitory effect on their downstream processing steps such as purification and amplification/detection. Although the Midass system was designed for the treatment of air samples, the first results on the integration of PC filters were encouraging. Nevertheless, system modifications are needed to better adapt the Midass system for the monitoring of the microbiological water quality. Copyright © 2015 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  16. Investigation on Nano composite Membrane of Multi walled Carbon Nano tube Reinforced Polycarbonate Blend for Gas Separation

    International Nuclear Information System (INIS)

    Kausar, A.

    2016-01-01

    Carbon nano tube has been explored as a nano filler in high performance polymeric membrane for gas separation. In this regard, nano composite membrane of polycarbonate (PC), poly(vinylidene fluoride-co-hexafluoropropylene) (PVFHFP), and multi walled carbon nano tube (MWCNT) was fabricated via phase inversion technique. Poly (ethylene glycol) (PEG) was employed for the compatibilization of the blend system. Two series of PC/PVFHFP/PEG were developed using purified P-MWCNT and acid functional A-MWCNT nano filler. Scanning and transmission electron micrographs have shown fine nano tube dispersion and wetting by matrix, compared with the purified system. Tensile strength and Young s modulus of PC/PVFHFP/PEG/MWCNT-A 1-5 were found to be in the range of 63.6-72.5 MPa and 110.6-122.1 MPa, respectively. The nano composite revealed 51% increase in Young s modulus and 28% increase in tensile stress relative to the pristine blend. The A-MWCNT was also effective in enhancing the perm selectivity αCO 2 /N 2 (31.2-39.9) of nano composite membrane relative to the blend membrane (21.6). The permeability ρCO 2 of blend was 125.6 barrer; however, the functional series had enhancedρCO 2 values ranging from 142.8 to 186.6 barrer. Moreover, A-MWCNT loading improved the gas diffusivity of PC/PVFHFP/PEG/MWCNT-A 1-5; however, filler content did not significantly influence the CO 2 and N 2 solubility.

  17. Recycling of engineering plastics from waste electrical and electronic equipments: influence of virgin polycarbonate and impact modifier on the final performance of blends.

    Science.gov (United States)

    Ramesh, V; Biswal, Manoranjan; Mohanty, Smita; Nayak, Sanjay K

    2014-05-01

    This study is focused on the recovery and recycling of plastics waste, primarily polycarbonate, poly(acrylonitrile-butadiene-styrene) and high impact polystyrene, from end-of-life waste electrical and electronic equipments. Recycling of used polycarbonate, acrylonitrile-butadiene-styrene, polycarbonate/acrylonitrile-butadiene-styrene and acrylonitrile-butadiene-styrene/high impact polystrene material was carried out using material recycling through a melt blending process. An optimized blend composition was formulated to achieve desired properties from different plastics present in the waste electrical and electronic equipments. The toughness of blended plastics was improved with the addition of 10 wt% of virgin polycarbonate and impact modifier (ethylene-acrylic ester-glycidyl methacrylate). The mechanical, thermal, dynamic-mechanical and morphological properties of recycled blend were investigated. Improved properties of blended plastics indicate better miscibility in the presence of a compatibilizer suitable for high-end application.

  18. The spark counting of etched fission-fragment tracks in polycarbonate for a personal neutron dosimetry system

    International Nuclear Information System (INIS)

    Harrison, K.G.; Hancock, I.B.; Holt, P.D.; Wylie, J.W.

    1977-10-01

    A new type of personal neutron dosimeter, in which neutron-induced fissions in a thin 237 Np foil are detected by a polycarbonate track-detector, is under development at Harwell for use in a nuclear-fuel reprocessing plant. As part of the development programme, an experimental dosimeter, etching facility and spark counter have been used to study the spark-counting method for counting fission-fragment tracks in polycarbonate. Emphasis has been placed on developing operating procedures for the counter consistent with good overall reproducibility. Existing methods for the optimizing and testing of spark counters is briefly reviewed and a practical operational testing procedure is devised. The optimized system is found to be relatively foolproof in operation and gives good results in unskilled use as well as under carefully-controlled laboratory conditions. (author)

  19. Growth of silicone-immobilized bacteria on polycarbonate membrane filters, a technique to study microcolony formation under anaerobic conditions.

    OpenAIRE

    Højberg, O; Binnerup, S J; Sørensen, J

    1997-01-01

    A technique was developed to study microcolony formation by silicone-immobilized bacteria on polycarbonate membrane filters under anaerobic conditions. A sudden shift to anaerobiosis was obtained by submerging the filters in medium which was depleted for oxygen by a pure culture of bacteria. The technique was used to demonstrate that preinduction of nitrate reductase under low-oxygen conditions was necessary for nonfermenting, nitrate-respiring bacteria, e.g., Pseudomonas spp., to cope with a...

  20. Hydrolysis of polycarbonate in sub-critical water in fused silica capillary reactor with in situ Raman spectroscopy

    Science.gov (United States)

    Pan, Z.; Chou, I-Ming; Burruss, R.C.

    2009-01-01

    The advantages of using fused silica capillary reactor (FSCR) instead of conventional autoclave for studying chemical reactions at elevated pressure and temperature conditions were demonstrated in this study, including the allowance for visual observation under a microscope and in situ Raman spectroscopic characterization of polycarbonate and coexisting phases during hydrolysis in subcritical water.

  1. Tracking of Polycarbonate Films using Low-energy Ions Final Report CRADA No. TC-774-94

    Energy Technology Data Exchange (ETDEWEB)

    Musket, R. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2018-01-24

    Ion tracking is performed almost exclusively using ions with energies near or above the maximum in electronic stopping. For the present study, we have examined the results of etching ion tracks created by ions bombarding polycarbonate films with energies corresponding to stopping well below the maximum and just above the anticipated threshold for creating etchable latent tracks. Low-energy neon and argon ions with 18-60 keV /amu and fluences of about 108/cm2 were used to examine the limits for producing etchable tracks in polycarbonate films. By concentrating on the early stages of etching (i.e., -20 nm < SEM hole diameter < -100 nm), we can directly relate the energy deposition calculated for the incident ion to the creation of etchable tracks. The experimental results will be discussed with regard to the energy losses of the ions in the polycarbonate films and to the formation of continuous latent tracks through the entire thickness the films. These results have significant implications with respect to the threshold for formation of etchable tracks and to the use of low-energy ions for lithographic applications.

  2. Texture Analysis of Hydrophobic Polycarbonate and Polydimethylsiloxane Surfaces via Persistent Homology

    Directory of Open Access Journals (Sweden)

    Ali Nabi Duman

    2017-09-01

    Full Text Available Due to recent climate change-triggered, regular dust storms in the Middle East, dust mitigation has become the critical issue for solar energy harvesting devices. One of the methods to minimize and prevent dust adhesion and create self-cleaning abilities is to generate hydrophobic characteristics on surfaces. The purpose of this study is to explore the topological features of hydrophobic surfaces. We use non-standard techniques from topological data analysis to extract morphological features from the AFM images. Our method recovers most of the previous qualitative observations in a robust and quantitative way. Persistence diagrams, which is a summary of topological structures, witness quantitatively that the crystallized polycarbonate (PC surface possesses spherulites, voids, and fibrils, and the texture height and spherulite concentration increases with the increased immersion period. The approach also shows that the polydimethylsiloxane (PDMS exactly copied the structures at the PC surface but 80 to 90 percent of the nanofibrils were not copied at PDMS surface. We next extract a feature vector from each persistence diagram to show which experiments hold features with similar variance using principal component analysis (PCA. The K-means clustering algorithm is applied to the matrix of feature vectors to support the PCA result, grouping experiments with similar features.

  3. SAXS investigation of un-etched and etched ion tracks in polycarbonate

    Science.gov (United States)

    Hossain, U. H.; Rodriguez, M. D.; Schauries, D.; Hadley, A.; Schleberger, M.; Trautmann, C.; Mudie, S.; Kluth, P.

    2017-10-01

    Investigation of the ion track morphologies and track etching behaviour in polycarbonate (PC) films was carried out using synchrotron based small-angle X-ray scattering (SAXS) measurements. The tracks were induced by Au ions with kinetic energies of 1.7 and 2.2 GeV with applied fluences between 1 × 1010 and 1 × 1012 ions/cm2. The average radii of the un-etched tracks were studied as a function of the irradiation fluence, indicating a general ion induced degradation of the polymer, with a simultaneous increase in ion track radius from 2.6 ± 0.002 nm to 3.4 ± 0.03 nm. Chemical etching of the ion tracks in PC leads to the formation of cylindrical pores. The pore radius increases linearly with etching time. In 3 M NaOH at 55 °C, a radial etching rate of 9.2 nm/min is observed.

  4. Photoluminescent study of Polycarbonate (PC) and Poly(9-vinylcarbazole) (PVK) doped films with europium complex

    International Nuclear Information System (INIS)

    Forster, Pedro Lima

    2010-01-01

    Polymers doped with rare earth complexes are advantaged in film production for many applications in the luminescent field. In this study luminescent polymer obtained from polycarbonate (PC) and poly(9-vinylcarbazole) films doped with diaquatris(thenoyltrifluoroacetonate)europium(III) complex [Eu(tta) 3 (H 2 0) 2 ] were prepared and their calorimetric and luminescent properties in the solid state are reported. The thermal behavior was investigated by differential scanning calorimetry (OSC) and thermogravimetry analysis (TGA). Due of the addition of rare earth Eu(tta) 3 (H 2 0) 2 ] into PC and PVK matrices, changes were observed in the thermal behavior concerning the glass transition and thermal stability. Characteristic broadened narrow bands arising from the 5 D 0 -→ 7 F J transitions (J = 0-4) of Eu 3+ ion indicate the incorporation of the Eu 3+ ions into those polymers. The luminescent films show enhancement emission intensity with an increase in the rare earth concentration in polymeric matrix accompanied by decrease in thermal stability. (author)

  5. Fabrication of a flexible polycarbonate/porphyrin film dosimeter for high dose dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Feizi, Shahzad [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of). Radiation Application Research School

    2017-10-01

    Dyed polycarbonate (PC) Radiochromic films with 20 μm thickness were prepared by casting of organic solution of PC containing 0.5 wt.% tetrakis (pentafluorophenyl) porphyrin (TPPF{sub 20}) on a glass petri dish. Characterization of the film as a routine dosimeter was studied. On subjecting PC/TPPF{sub 20} film dosimeter to gamma radiation, a gradual decrease in the color of films was observed. The sensitivity of these films and the linearity of dose-response curves were studied under {sup 60}Co γ-rays expose in dose range of 0-100 kGy. The results were compared with the commercial and non-commercial dosimeters. Experimental parameters including humidity, temperature and pre-irradiation (shelf-life) and post-irradiation storage in dark and in indirect sunlight were examined. The maximum absorbance of soret band of TPPF{sub 20} had a bathochromic shift and appeared at 414 nm which remained intact in the investigated dose range. The dyed films characteristics were found to be stable enough in media with high degrees of temperature and humidity. The results indicate that radiation induced decoloration of PC/TPPF{sub 20} films can be reliably used in high dose dosimetry.

  6. Confinement of phonon propagation in laser deposited tungsten/polycarbonate multilayers

    International Nuclear Information System (INIS)

    Döring, Florian; Pagel, Sinja; Eberl, Christian; Erichsen, Torben; Krebs, Hans-Ulrich; Ulrichs, Henning; Müller, Markus; Mansurova, Maria; Müller, Matthias; Mann, Klaus; Huebner, Dennis; Vana, Philipp; Münzenberg, Markus

    2016-01-01

    Nanoscale multilayer thin films of W and PC (Polycarbonate) show, due to the great difference of the components’ characteristics, fascinating properties for a variety of possible applications and provide an interesting research field, but are hard to fabricate with low layer thicknesses. Because of the great acoustic mismatch between the two materials, such nanoscale structures are promising candidates for new phononic materials, where phonon propagation is strongly reduced. In this article we show for the first time that W/PC-multilayers can indeed be grown with high quality by pulsed laser deposition. We analyzed the polymer properties depending on the laser fluence used for deposition, which enabled us to find best experimental conditions for the fabrication of high-acoustic-mismatch W/PC multilayers. The multilayers were analyzed by fs pump-probe spectroscopy showing that phonon dynamics on the ps time-scale can strongly be tailored by structural design. While already periodic multilayers exhibit strong phonon localization, especially aperiodic structures present outstandingly low phonon propagation properties making such 1D-layered W/PC nano-structures interesting for new phononic applications. (fast track communication)

  7. On crystallization of bisphenol-A polycarbonate thin films upon annealing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chunhong; Li, Qichao; Mao, Wenfeng; Wang, Peng; He, Chunqing, E-mail: hecq@whu.edu.cn

    2015-10-16

    Crystallization of polycarbonate (PC) films as a function of annealing time has been investigated by various methods. A distinct diffraction peak at 17.56°, a sharp decrease of film thickness, an increase of refractive index and branch-type structures on the surface are found merely for the film after crystallization. Interestingly, positron annihilation parameters demonstrate fractional free-volumes in PC films vary significantly not only before crystallization but also at the early stage of annealing, which are not found by other methods. The results show that free-volumes in PC film must be increased remarkably before crystallization, which enables the occurrence of molecule rearrangement. - Highlights: • Fractional free-volume in PC film decreased of early stage of annealing. • Crystallization of PC film on Si substrate occurred after annealed for ∼48 hours. • Fractional free-volume in PC film increased remarkably before crystallization. • Positron diffusion length and S parameter revealed the variation of free volumes.

  8. Environmental stress cracking in gamma-irradiated polycarbonate - A diffusion approach

    Science.gov (United States)

    Silva, Pietro Paolo J. C. de O.; Araújo, Patricia L. B.; da Silveira, Leopoldo B. B.; Araújo, Elmo S.

    2017-01-01

    Polycarbonate (PC) is an engineering polymer which presents interesting properties. This material has been also used in medical devices, which is frequently exposed to gamma radiosterilization and to chemical agents. This may produce significant changes in polymer structure, leading to failure in service. The present work brings about a new approach on environmental stress cracking (ESC) processes elucidation in 100 kGy gamma-irradiated PC, by evaluating the diffusion process of methanol or 2-propanol in test specimens and determining the diffusion parameters on solvent-irradiated polymer systems. A comparison of diffusion parameters for both solvents indicated that methanol has a considerable ESC action on PC, with diffusion parameter of 7.5×10-14±1% m2 s-1 for non-irradiated PC and 7.8×10-14±2.8% m2 s-1 for PC irradiated at 100 kGy. In contrast, 2-propanol did not act as an ESC agent, as it did promote neither swelling nor cracks in the test specimens. These results were confirmed by visual analysis and optical microscopy. Unexpectedly, structural damages evidenced in tensile strength tests suggested that 2-propanol is as aggressive as methanol chemical for PC. Moreover, although some manufacturers indicate the use of 2-propanol as a cleaning product for PC artifacts, such use should be avoided in parts under mechanical stress.

  9. Surface evolution of polycarbonate/polyethylene terephthalate blends induced by thermal treatments

    Energy Technology Data Exchange (ETDEWEB)

    Licciardello, A.; Auditore, A.; Samperi, F.; Puglisi, C

    2003-01-15

    Bisphenol-A polycarbonate (PC) and polyethyleneterephthalate (PET) blends are known to undergo, upon thermal treatment (melt mixing), exchange reactions leading to the formation of copolymers having a final structure that is also affected by consecutive reactions involving CO{sub 2} and ethylene carbonate losses. In this work we followed the evolution of the surface composition of this system during the melt mixing at 270 deg. C, both with and without catalysts, by means of time-of-flight secondary ion mass spectroscopy (ToF-SIMS). The static SIMS spectra obtained at different treatment times show the appearance of peaks related to newly formed structures and also the modification of the relative intensities of peaks characteristic of both the initial constituents of the blend. From the variation of the relative intensities of peaks related to the bisphenol-A unit of PC and to the phthalate structure of PET, it is shown that after the first stages of melt mixing the surface is PC enriched and that with the progressive formation of a random copolymer the phthalate units increase their concentration at the surface of the system. Hence, as final result of the melt mixing process, the surface composition tends to reflect the relative amount of the repeating units in the bulk.

  10. Anti-biofilm efficacy of 100 MeV gold ion irradiated polycarbonate against Salmonella typhi

    Science.gov (United States)

    Joshi, R. P.; Hareesh, K.; Bankar, A.; Sanjeev, G.; Asokan, K.; Kanjilal, D.; Dahiwale, S. S.; Bhoraskar, V. N.; Dhole, S. D.

    2017-12-01

    Polycarbonate (PC) films were irradiated by 100 MeV gold (Au7+) ions and characterized to study changes in its optical, chemical, surface morphology and thermal properties. UV-Visible spectroscopic results revealed the decrease in the optical band gap of PC after ion irradiation due to chain scission mainly at the carbonyl group which is corroborated by Fourier Transform Infrared spectroscopic results. X-ray diffractogram study showed decrease in crystallinity of PC film after irradiation. Scanning electron microscopic results showed the micropores formation in PC which results in surface roughening. Differential scanning calorimetric results revealed decrease in glass transition temperature indicating the decrease in molecular weight of PC corroborated by rheometric studies. PC films irradiated by 100 MeV Au7+ ions showed increased anti-biofilm activity against the human pathogen, Salmonella typhi (S. typhi). Morphology of S. typhi was changed due to stress of Au7+ irradiated PC. Cells length was increased with increasing fluences. The average cell length, cell volume and surface area was increased significantly (P<0.05) with increasing ion fluences. Biofilm formation was inhibited ≈ 20% at lower fluence and 96% at higher fluence, which observed to be enhanced anti-biofilm activity in Au7+ irradiated PC.

  11. A study of commercially-available polyethylene terephthalate (PET) and polycarbonate as nuclear track detector materials

    Science.gov (United States)

    Espinosa, G.; Golzarri, J. I.; Vazquez-Lopez, C.; Trejo, R.; Lopez, K.; Rickards, J.

    2014-07-01

    In the study of the sensitivity of materials to be used as nuclear track detectors, it was found that commercial polyethylene terephthalate (PET) from Ciel® water bottles, commercial roof cover polycarbonate, and recycled packaging strips (recycled PET), can be used as nuclear track detectors. These three commercial materials present nuclear tracks when bombarded by 2.27 MeV nitrogen ions produced in a Pelletron particle accelerator, and by fission fragments from a 252Cf source (79.4 and 103.8 MeV), after a chemical etching with a 6.25M KOH solution, or with a 6.25M KOH solution with 20% methanol, both solutions at 60±1°C. As an example, the nitrogen ions deposit approximately 1 keV/nm in the form of ionization and excitation at the surface of PET, as calculated using the SRIM code. The fission fragments deposit up to 9 keV/nm at the surface, in both cases generating sufficient free radicals to initiate the track formation process. However, 5 MeV alpha particles, typical of radon (222Rn) emissions, deposit only 0.12 keV/nm, do not present tracks after the chemical etching process. This valuable information could be very useful for further studies of new materials in nuclear track methodology.

  12. Enhancement of low power CO2 laser cutting process for injection molded polycarbonate

    Science.gov (United States)

    Moradi, Mahmoud; Mehrabi, Omid; Azdast, Taher; Benyounis, Khaled Y.

    2017-11-01

    Laser cutting technology is a non-contact process that typically is used for industrial manufacturing applications. Laser cut quality is strongly influenced by the cutting processing parameters. In this research, CO2 laser cutting specifications have been investigated by using design of experiments (DOE) with considering laser cutting speed, laser power and focal plane position as process input parameters and kerf geometry dimensions (i.e. top and bottom kerf width, ratio of the upper kerf to lower kerf, upper heat affected zone (HAZ)) and surface roughness of the kerf wall as process output responses. A 60 Watts CO2 laser cutting machine is used for cutting the injection molded samples of polycarbonate sheet with the thickness of 3.2 mm. Results reveal that by decreasing the laser focal plane position and laser power, the bottom kerf width will be decreased. Also the bottom kerf width decreases by increasing the cutting speed. As a general result, locating the laser spot point in the depth of the workpiece the laser cutting quality increases. Minimum value of the responses (top kerf, heat affected zone, ratio of the upper kerf to lower kerf, and surface roughness) are considered as optimization criteria. Validating the theoretical results using the experimental tests is carried out in order to analyze the results obtained via software.

  13. Estrogenic chemicals often leach from BPA-free plastic products that are replacements for BPA-containing polycarbonate products.

    Science.gov (United States)

    Bittner, George D; Yang, Chun Z; Stoner, Matthew A

    2014-05-28

    Xenobiotic chemicals with estrogenic activity (EA), such as bisphenol A (BPA), have been reported to have potential adverse health effects in mammals, including humans, especially in fetal and infant stages. Concerns about safety have caused many manufacturers to use alternatives to polycarbonate (PC) resins to make hard and clear, reusable, plastic products that do not leach BPA. However, no study has focused on whether such BPA-free PC-replacement products, chosen for their perceived higher safety, especially for babies, also release other chemicals that have EA. We used two, well-established, mammalian cell-based, assays (MCF-7 and BG1Luc) to assess the EA of chemicals that leached into over 1000 saline or ethanol extracts of 50 unstressed or stressed (autoclaving, microwaving, and UV radiation) BPA-free PC-replacement products. An EA antagonist, ICI 182,780, was used to confirm that agonist activity in leachates was due to chemicals that activated the mammalian estrogen receptor. Many unstressed and stressed, PC-replacement-products made from acrylic, polystyrene, polyethersulfone, and Tritan™ resins leached chemicals with EA, including products made for use by babies. Exposure to various forms of UV radiation often increased the leaching of chemicals with EA. In contrast, some BPA-free PC-replacement products made from glycol-modified polyethylene terephthalate or cyclic olefin polymer or co-polymer resins did not release chemicals with detectable EA under any conditions tested. This hazard assessment survey showed that many BPA-free PC- replacement products still leached chemicals having significant levels of EA, as did BPA-containing PC counterparts they were meant to replace. That is, BPA-free did not mean EA-free. However, this study also showed that some PC-replacement products did not leach chemicals having significant levels of EA. That is, EA-free PC-replacement products could be made in commercial quantities at prices that compete with PC

  14. Dietary exposure assessment of infants to bisphenol A from the use of polycarbonate baby milk bottles.

    Science.gov (United States)

    Onn Wong, Kwok; Woon Leo, Lay; Leng Seah, Huay

    2005-03-01

    The residual bisphenol A (BPA) levels in 28 different brands of polycarbonate (PC) baby milk bottles available in the Singapore market were measured. With a detection limit of 3 mg/kg, BPA residues were detected in 19 out of the 28 PC baby milk bottles at levels between 4.01 and 141 mg/kg, with a mean of 28.1 +/- 31.4 mg/kg and a median of 17.2 mg/kg. The potential migration of BPA from each of the 28 PC milk bottles was also measured using food-simulating solvents and time conditions recommended by the US Food and Drug Administration (US FDA), but using temperatures more severe than actual use. The highest upper-bound mean BPA migration levels of 0.64 +/- 0.48 microg/in2 in 10% ethanol at 70 degrees C and 0.43 +/- 1.25 microg/in2 in corn oil at 100 degrees C were observed after incubating cut portions of the milk bottles for 240 h. With this migration data and using US FDA's procedure for estimation of dietary exposure, the worst-case dietary exposure assessment for the intake of BPA by infants between birth and three months of age was below the oral Reference Dose of 0.05 mg/kg bw/day established by the US Environmental Protection Agency. This study showed that the dietary exposure to BPA from actual uses of PC milk bottles is unlikely to pose a health risk in infants.

  15. Degradation studies on biodegradable nanocomposite based on polycaprolactone/polycarbonate (80:20%) polyhedral oligomeric silsesquioxane.

    Science.gov (United States)

    Raghunath, Joanne; Georgiou, George; Armitage, David; Nazhat, Showan N; Sales, Kevin M; Butler, Peter E; Seifalian, Alexander M

    2009-12-01

    The development of biocompatible polymers has greatly advanced the field of tissue engineering. Some tissues can be propagated on a nondegradable scaffold. Tissue such as cartilage, however, is a complex tissue in which the chondrocytes require their own synthesized extracellular matrix (ECM) to function. Suitable scaffolds for tissue engineering cartilage should provide mechanical strength and degrade at a similar rate to that of cell growth and ECM production. We have developed a biodegradable nanocomposite based on polycaprolactone and polycarbonate polyurethane (PCU) with an incorporated polyhedral oligomeric silsesquioxane (POSS) (POSS modified Poly(caprolactone/carbonate) urethane/urea). Previous work on POSS incorporated into PCU (POSS-PCU) has been shown to possess good mechanical strength, elasticity and resistance to degradation. This series of experiments involved exposing this polymer to a selection of accelerated degradative solutions for up to 8 weeks. The samples were analyzed by infra-red spectroscopy, scanning electron microscopy, X-ray microanalysis, contact angle analysis, and stress-strain mechanical analysis. Degradation of hard and soft segments of the nanocomposite was evident by infra-red spectroscopy in all conditioned samples. POSS nanocage degradation was evident in some oxidative/peroxidative systems accompanied by gross changes in surface topography and significant changes in mechanical properties. The hydrophobic polymer became more hydrophilic in all conditions. This biodegradable nanocomposite demonstrated steady degradation with protection of mechanical properties when exposed to hydrolytic enzymes and plasma protein fractions and exhibited more dramatic degradation by oxidation.This pattern may be potentially employed in tissue engineering scaffolds where controlled degradation and retained structural stability of the scaffold is required. Copyright 2008 Wiley Periodicals, Inc.

  16. Surface free energy of polypropylene and polycarbonate solidifying at different solid surfaces

    International Nuclear Information System (INIS)

    Chibowski, Emil; Terpilowski, Konrad

    2009-01-01

    Advancing and receding contact angles of water, formamide, glycerol and diiodomethane were measured on polypropylene (PP) and polycarbonate (PC) sample surfaces which solidified at Teflon, glass or stainless steel as matrix surfaces. Then from the contact angle hystereses (CAH) the apparent free energies γ s tot of the surfaces were evaluated. The original PP surface is practically nonpolar, possessing small electron donor interaction (γ s - =1.91mJ/m 2 ), as determined from the advancing contact angles of these liquids. It may result from impurities of the polymerization process. However, it increases up to 8-10 mJ/m 2 for PP surfaces contacted with the solids. The PC surfaces both original and modified show practically the same γ s - =6.56.7mJ/m 2 . No electron acceptor interaction is found on the surfaces. The γ s tot of modified PP and PC surfaces depend on the kind of probe liquid and contacted solid surface. The modified PP γ s tot values determined from CAH of polar liquids are greater than that of original surface and they increase in the sequence: Teflon, glass, stainless steel surface, at which they solidified. No clear dependence is observed between γ s tot and dielectric constant or dipole moment of the polar probe liquids. The changes in γ s tot of the polymer surfaces are due to the polymer nature and changes in its surface structure caused by the structure and force field of the contacting solid. It has been confirmed by AFM images.

  17. Conditions of rib design for polycarbonate resin with high glossy surfaces

    International Nuclear Information System (INIS)

    Jeong, Seong Won

    2013-01-01

    Much attention has been being given to the importance of product surfaces in the field of plastic parts, as industrial design has become one of the key elements of product success. These plastic parts incorporate rib-like geometries on the non-appearance surfaces of plastic in order to increase the stiffness of rigidity of the section, but they often cause appearance problems of the product's surface overall by making a sink mark on that surface. The thickness, height and draft-angle of the rib are generally known as major parameters influencing the sink mark on the appearance surface. Therefore, designers of plastic parts must determine the variables of reinforcing ribs. The goal of this study is to find the optimum design variables in the mixing conditions of the thickness, the height and the draft angle of reinforcing ribs so that designers of plastic parts can easily determine the conditions of the reinforcing ribs as the part's section thickness varies within an objective limit in polycarbonate plastic resin and a high glossy surface that are widely applied in the creation of plastic products. We investigated the actual depths of sink marks on the surface of a specimen that was manufactured with an injection mold specifically for this study. Response surface methodology with the Box-Behnken design was used to analyze the regression curve of real depths with combinations of the thickness, height and draft angle of the ribs. The result shows that the most influential factor to increase the shrinkage is the thickness of ribs and that the optimum value of the rib thickness is a range from multiple of 0.25 to 0.34 of the section thickness. Also, the rib height and rib draft angle are not major factors that can change the sink amount.

  18. Conditions of rib design for polycarbonate resin with high glossy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Seong Won [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2013-10-15

    Much attention has been being given to the importance of product surfaces in the field of plastic parts, as industrial design has become one of the key elements of product success. These plastic parts incorporate rib-like geometries on the non-appearance surfaces of plastic in order to increase the stiffness of rigidity of the section, but they often cause appearance problems of the product's surface overall by making a sink mark on that surface. The thickness, height and draft-angle of the rib are generally known as major parameters influencing the sink mark on the appearance surface. Therefore, designers of plastic parts must determine the variables of reinforcing ribs. The goal of this study is to find the optimum design variables in the mixing conditions of the thickness, the height and the draft angle of reinforcing ribs so that designers of plastic parts can easily determine the conditions of the reinforcing ribs as the part's section thickness varies within an objective limit in polycarbonate plastic resin and a high glossy surface that are widely applied in the creation of plastic products. We investigated the actual depths of sink marks on the surface of a specimen that was manufactured with an injection mold specifically for this study. Response surface methodology with the Box-Behnken design was used to analyze the regression curve of real depths with combinations of the thickness, height and draft angle of the ribs. The result shows that the most influential factor to increase the shrinkage is the thickness of ribs and that the optimum value of the rib thickness is a range from multiple of 0.25 to 0.34 of the section thickness. Also, the rib height and rib draft angle are not major factors that can change the sink amount.

  19. High electronic excitation induced modifications by 100 MeV O7+ and 150 MeV Ni11+ ions in Makrofol KG polycarbonate film

    Science.gov (United States)

    Kumar, Vijay; Sonkawade, R. G.; Dhaliwal, A. S.

    2012-09-01

    Makrofol-KG polycarbonate (M-KG PC) films are irradiated with 150 MeV Ni11+ and 100 MeV O7+ ion beams at various fluences ranging from 1 × 1011 to 3 × 1012 ions/cm2. We have investigated the effect of irradiation parameters such as energy and ions fluence on optical, structural and chemical properties of the studied polymer, respectively. UV-Visible, Fourier Transform Infrared (FTIR) and X-ray diffraction (XRD) spectral studies have been employed in the present investigation. UV-Visible spectra exhibit a shift towards the higher wavelength regime after irradiation. This shift clearly reflects decrease in optical band gap after irradiation. The FTIR spectrum shows a decrease in intensity of the typical bands whereas the formation of new bands indicates the degradation of the polymer after irradiation. The XRD pattern of M-KG PC shows the decreasing intensity of peak positions with increase in ions fluence, which suggests loss of crystallinity of the films due to irradiation. Observed results indicate the formation of disordered system in the irradiated films. Magnitude of effect of irradiation is greater in case of 150 MeV Ni11+ rather than 100 MeV O7+ ions due to high electronic energy loss of Ni11+ ions in M-KG PC. The results can be correlated on the basis of linear energy transfer (LET) of the irradiated ions.

  20. Novel single-cell mega-size chambers for electrochemical etching of panorama position-sensitive polycarbonate ion image detectors

    Science.gov (United States)

    Sohrabi, Mehdi

    2017-11-01

    A novel development is made here by inventing panorama single-cell mega-size electrochemical etching (MS-ECE) chamber systems for processing panorama position-sensitive mega-size polycarbonate ion image detectors (MS-PCIDs) of potential for many neutron and ion detection applications in particular hydrogen ions or proton tracks and images detected for the first time in polycarbonates in this study. The MS-PCID is simply a large polycarbonate sheet of a desired size. The single-cell MS-ECE invented consists of two large equally sized transparent Plexiglas sheets as chamber walls holding a MS-PCID and the ECE chamber components tightly together. One wall has a large flat stainless steel electrode (dry cell) attached to it which is directly in contact with the MS-PCID and the other wall has a rod electrode with two holes to facilitate feeding and draining out the etching solution from the wet cell. A silicon rubber washer plays the role of the wet cell to hold the etchant and the electrical insulator to isolate the dry cell from the wet cell. A simple 50 Hz-HV home-made generator provides an adequate field strength through the two electrodes across the MS-ECE chamber. Two panorama single-cell MS-ECE chamber systems (circular and rectangular shapes) constructed were efficiently applied to processing the MS-PCIDs for 4π ion emission image detection of different gases in particular hydrogen ions or protons in a 3.5 kJ plasma focus device (PFD as uniquely observed by the unaided eyes). The panorama MS-PCID/MS-ECE image detection systems invented are novel with high potential for many applications in particular as applied to 4π panorama ion emission angular distribution image detection studies in PFD space, some results of which are presented and discussed.

  1. The waterborne polyurethane dispersions based on polycarbonate diol: effect of ionic content

    Czech Academy of Sciences Publication Activity Database

    Cakić, S. M.; Špírková, Milena; Ristić, I. S.; B-Simendić, J. K.; M-Cincović, M.; Poreba, Rafal

    2013-01-01

    Roč. 138, č. 1 (2013), s. 277-285 ISSN 0254-0584 R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : coatings * chemical synthesis * thermogravimetric analysis (TGA) Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.129, year: 2013

  2. Influence of flavour absorption by food-packaging materials (low-density polyethylene, polycarbonate and polyethylene terephthalate) on taste perception of a model solution and orange juice

    NARCIS (Netherlands)

    Willige, van R.W.G.; Linssen, J.P.H.; Legger, A.; Voragen, A.G.J.

    2003-01-01

    The influence of flavour absorption by low-density polyethylene (LDPE), polycarbonate (PC) and polyethylene terephthalate (PET) on taste perception of a model solution containing seven flavour compounds and orange juice in glass bottles was studied with and without pieces of the respective plastic

  3. Aliphatic polycarbonate-based polyurethane elastomers and nanocomposites. I. The influence of hard-segment content and macrodiol-constitution on bottom-up self-assembly

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Poreba, Rafal; Pavličevič, Jelena; Kobera, Libor; Baldrian, Josef; Pekárek, Michal

    2012-01-01

    Roč. 126, č. 3 (2012), s. 1016-1030 ISSN 0021-8995 R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane elastomer * polycarbonate diol * nanocomposite Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.395, year: 2012

  4. Identification and quantification of bisphenol A and bisphenol B in polyvinylchloride and polycarbonate medical devices by gas chromatography with mass spectrometry.

    Science.gov (United States)

    Gimeno, Pascal; Spinau, Coline; Lassu, Nelly; Maggio, Annie-Françoise; Brenier, Charlotte; Lempereur, Laurent

    2015-11-01

    A gas chromatography with mass spectrometry method has already been developed and published for the identification and quantification of 14 phthalates and five nonphthalate plasticizers in polyvinylchloride medical devices. In order to assay, in addition to plasticizers, bisphenols A and B possibly present in polyvinylchloride samples, this previous method was extended to the assay of these additional potential endocrine disruptors. Furthermore, as bisphenol A could also be present in polycarbonate samples, the method used for the polyvinylchloride sample was tested and validated for the assay of bisphenols A and B in polycarbonate medical devices. The separation of all compounds, including bisphenols A and B, is obtained on a cross-linked 5%-phenyl/95%-dimethylpolysiloxane capillary column using a temperature gradient. For both plastics, samples are dissolved in tetrahydrofuran followed by a precipitation of the plastic by addition of ethanol. Results obtained point out residual bisphenol A amounts for polycarbonate samples ranging from 0.6 to 0.8% and for polyvinylchloride samples less or equal to 5 ppm. No bisphenol B was detected in the samples tested. For bisphenols A and B, mean recoveries obtained on spiked polyvinylchloride or polycarbonate sample preparations ranged from 87 to 108% in accordance with in-house specification (80-110%). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Surface modification of bisphenol A polycarbonate material by ultraviolet Nd:YVO4 laser high-speed microprocessing technology

    International Nuclear Information System (INIS)

    Liu, Jianguo; Wang, Suhuan; Lv, Ming; Zeng, Xiaoyan

    2014-01-01

    In this paper, a low-cost and high-efficiency microprocessing modification technology for the surface of bisphenol A polycarbonate (BAPC) material was achieved (in particular, from hydrophilicity to hydrophobicity) at high laser scanning speeds (600–1000 mm s  − 1 ) and using an all-solid state, Q-switched, high-average power and nanosecond pulse Nd:YVO 4 laser (355 nm wavelength). During the modification, it was found that the laser fluence and pulse width were the two main parameters affecting the modification effect. Moreover, the modification had a significant effect on the water contact angle, wetting behavior, microstructure, average roughness and chemical composition of the surface. When the laser fluences applied were low (i.e., less than the so-called critical fluence of the UV laser modification of the BAPC material), the water contact angle was found to be a little less than the original, the hydrophilicity was slightly improved, the relative content of the oxygen-containing groups (e.g. O–C and COO  −  ) increased, the microstructure and average roughness only had a very slight change, and the wetting behavior complied with the Wenzel regime. On the other hand, when the laser fluences applied were high, the water contact angle significantly increased, the hydrophilicity markedly decreased and the relative content of the oxygen-containing groups also increased. Here, a porous microstructure with periodical v-type grooves was generated and the average roughness had an obvious increase. In this case, the wetting behavior could be explained by the Cassie-Baxter regime, i.e., the microstructure and average roughness change played a deciding role. The reason for this might be that different laser parameters result in different material deformation and removal processes, thereby resulting in different surface chemical compositions, microstructures, roughnesses and wetting properties. (paper)

  6. ECE laboratory in the Vinča institute: Its basic characteristics and fundamentals of electrochemic etching on polycarbonate

    Directory of Open Access Journals (Sweden)

    Žunić Zora S.

    2003-01-01

    Full Text Available This paper deals with the introductory aspects of the Electrochemical Etching Laboratory installed at the VINČA Institute in the year 2003. The main purpose of the laboratory is its field application for radon and thoron large-scale survey using passive radon/thoron UFO type detectors. Since the etching techniques together with the laboratory equipment were transferred from the National Institute of Radiological Sciences, Chiba, Japan, it was necessary for both etching conditions to be confirmed and to be checked up^ i. e., bulk etching speeds of chemical etching and electrochemical etching in the VINCA Electrochemical Etching Laboratory itself. Beside this initial step, other concerns were taken into consideration in this preliminary experimental phase such as the following: the measurable energy range of the polycarbonate film, background etch pit density of the film and its standard deviation and reproducibility of the response to alpha particles for different sets of etchings.

  7. Comparison of the efficiency of polycarbonate and mixed cellulose ester filters for use in the filtration of water samples

    Energy Technology Data Exchange (ETDEWEB)

    Brackett, K.A.; Clark, P.J.

    1993-01-01

    The federal standard for the presence of asbestos in drinking water mandates the use of transmission electron microscopy (TEM) as the only acceptable testing method. The July 17, 1992 Federal Register specifies that the analysis for asbestos shall be conducted by the EPA Protocol entitled Analytical Method for Determination of Asbestos Fibers in Water (EPA-600/4-83) developed by Chatfield and Dillon (1), using polycarbonate (PC) membrane filters. A separate document (1993) providing guidance and clarification of the Chatfield method has been peer reviewed, which allows some slight changes to what was originally a research method, but still requires the use of PC filters. A draft of an alternative method using mixed cellulose ester (MCE) membrane filters was recently published in The Microscope (2). The experiment was designed to determine the quantitative differences between the two methods for all fiber lengths as well as for the regulated fibers > or = 10 micrometers in length.

  8. Lithium-Assisted Copolymerization of CO 2 /Cyclohexene Oxide: A Novel and Straightforward Route to Polycarbonates and Related Block Copolymers

    KAUST Repository

    Zhang, Dongyue

    2016-03-23

    A facile route toward alternating polycarbonates by anionic copolymerization of carbon dioxide (CO2) and cyclohexene oxide (CHO), using lithium halide or alkoxide as initiators and triisobutylaluminum (TiBA) as activator, is reported. α,ω-Heterobifunctional and α,ω-dihydroxypoly(cyclohexene carbonate)s (PCHC) as well as poly(CHC-co-CHO) copolymers with different carbonate composition could also be easily synthesized by adjusting the amount of TiBA or by adding inert lithium salts. The value of this initiating system also resides in the easy access to PSt-b-PCHC (PSt: polystyrene) and PI-b-PCHC (PI: polyisoprene) block copolymers which can be derived by mere one-pot sequential addition of styrene or dienes first and then of CO2 and CHO under the same experimental conditions. © 2016 American Chemical Society.

  9. Determination of Quantitative Structure-Property Relationships of Solvent Resistance of Polycarbonate Copolymers Using a Resonant Multisensor System

    Science.gov (United States)

    Potyrailo, Radislav A.; Wroczynski, Ronald J.; McCloskey, Patrick J.; Morris, William G.

    In sensor and microfluidic applications, the need is to have an adequate solvent resistance of polymers to prevent degradation of the substrate surface upon deposition of sensor formilations, to prevent contamination of the solvent-containing sensor formulations or contamination of organic liquid reactions in microfluidic channels. Unfortunately, no comprehensive quantitative reference solubility data of unstressed copolymers is available to date. In this study, we evaluate solvent-resistance of several polycarbonate copolymers prepared from the reaction of hydroquinone (HQ), resorcinol (RS), and bisphenol A (BPA). Our high-throughput polymer evaluation approach permitted the construction of detailed solvent-resistance maps, the development of quantitative structure-property relationships for BPA-HQ-RS copolymers and provided new knowledge for the further development of the polymeric sensor and microfluidic components.

  10. Growth of silicone-immobilized bacteria on polycarbonate membrane filters, a technique to study microcolony formation under anaerobic conditions

    DEFF Research Database (Denmark)

    Højberg, Ole; Binnerup, S. J.; Sørensen, Jan

    1997-01-01

    A technique was developed to study microcolony formation by silicone- immobilized bacteria on polycarbonate membrane filters under anaerobic conditions. A sudden shift to anaerobiosis was obtained by submerging the filters in medium which was depleted for oxygen by a pure culture of bacteria....... The technique was used to demonstrate that preinduction of nitrate reductase under low-oxygen conditions was necessary for nonfermenting, nitrate-respiring bacteria, e.g., Pseudomonas spp., to cope with a sudden lack of oxygen. In contrast, nitrate-respiring, fermenting bacteria, e.g., Bacillus and Escherichia...... spp, formed microcolonies under anaerobic conditions with or without the presence of nitrate and irrespective of aerobic or anaerobic preculture conditions....

  11. Experimental Study and Modelling of Poly (Methyl Methacrylate) and Polycarbonate Compressive Behavior from Low to High Strain Rates

    Science.gov (United States)

    El-Qoubaa, Z.; Colard, L.; Matadi Boumbimba, R.; Rusinek, A.

    2018-03-01

    This paper concerns an experimental investigation of Polycarbonate and Poly (methyl methacrylate) compressive behavior from low to high strain rates. Experiments were conducted from 0.001/s to ≈ 5000/s for PC and from 0.001/s to ≈ 2000/s for PMMA. The true strain-stress behavior is established and analyzed at various stain rates. Both PC and PMMA mechanical behavior appears as known, to be strain rate and temperature dependent. The DSGZ model is selected for modelling the strain-stress curves while the yield stress is reproduced using the cooperative model and a modified Eyring equation based on Eyring first process theory. All the three models predictions are in agreement with experiments performed on PC and PMMA.

  12. Migration of bisphenol A from polycarbonate baby bottles purchased in the Spanish market by liquid chromatography and fluorescence detection.

    Science.gov (United States)

    Santillana, M I; Ruiz, E; Nieto, M T; Bustos, J; Maia, J; Sendón, R; Sánchez, J J

    2011-11-01

    During the last decade the safety of bisphenol A (BPA) monomer in polycarbonate baby bottles has drawn the attention of both the public and the scientific community. This paper presents the results of BPA migration from polycarbonate baby bottles bought in the Spanish market, into simulant B (3% acetic acid), 50% ethanol and into real food (reconstituted infant formula). Furthermore, it was also the objective of this study to assess the suitability of 50% ethanol as a simulant for infant formula. BPA was analysed by a multi-analyte liquid chromatography method with fluorescence detection and mass spectrometry confirmation. The method was in-house validated and accredited by the national accreditation body. The validation results for this analyte in the previous mentioned matrices were: LOD = 0.004-0.007 mg kg(-1); LOQ (validated) = 0.03 mg kg(-1); RSD% = 3.4-5.8; and recovery = 106.6-118.2%. A collection of 72 different baby bottle samples from 12 different brands were analysed. Baby bottle material was identified by FTIR. The migration test conditions used were those recommended for baby bottles in the Guidelines on testing conditions for articles in contact with foodstuffs (with a focus on kitchenware), prepared by the European network of laboratories for food-contact materials. In most of the migration assays the results were below the LOD. In four of the commercial brands there was detectable migration into the simulant 50% ethanol and BPA was detected in only two samples of infant formula (0.01 mg kg(-1)). Migration results obtained were in compliance with European Union regulations.

  13. Acetal Resins, Acrylic & Modacrylic Fibers, Carbon Black, Hydrogen Fluoride, Polycarbonate, Ethylene, Spandex & Cyanide Chemical Manufacturing: NESHAP for Source Categories, Generic Maximum Achievable Control Technology Standards (40 CFR 63, Subpart YY)

    Science.gov (United States)

    Learn about the NESHAP for GMACT for acetal resins, hydrogen fluoride, polycarbonate, ethylene production and cyanide chemicals. Find the rule history information, federal register citations, legal authority, rule summary, and additional resources

  14. Use of additives to fine-tune the composition of carbonate units in the polymer formed by copolymerization of co2 with epoxide: application to the synthesis of polycarbonate-based block copolymers and of telechelics

    KAUST Repository

    Feng, Xiaoshuang

    2016-12-22

    Embodiments of the present disclosure describe a method of making a polycarbonate, comprising contacting one or more cyclic monomers and carbon dioxide in the presence of one or more of a Lewis acid catalyst, an initiator, and an ionic liquid; and agitating, sufficient to copolymerize the one or more cyclic monomers and carbon dioxide to create a polycarbonate. Embodiments of the present disclosure further describe a method of controlling a polymer composition, comprising contacting one or more cyclic monomers and carbon dioxide; adjusting an amount of one or more of a Lewis acid catalyst, an ionic liquid, and an initiator in the presence of the one or more cyclic monomers and carbon dioxide, sufficient to selectively modify a resulting polycarbonate; and agitating, sufficient to copolymerize the one or more cyclic monomers and carbon dioxide to create the polycarbonate.

  15. A comparative study of track registration response of Makrofol-(KG, KL and N) polycarbonate to sup 4 sup 0 Ar ions

    CERN Document Server

    Kumar, A

    1999-01-01

    In the present work a comparative study of track registration response of sup 4 sup 0 Ar ions in different types of Makrofol polycarbonates viz. Makrofol-KG, KL and N have been done. The etched track parameters viz. bulk etch rate, track etch rate, etch rate ratio, cone angle and etching efficiency were calculated. The variation of etching rates with temperature were found to be exponential and follow the Arrhenius equation. The values of activation energy for bulk and track etching were also calculated. Maximum etchable track length/range were also obtained and compared with the theoretical values obtained from computer program RANGE. From the results it is found that the polycarbonates having same chemical composition manufactured by different chemical processes have slightly different behavior

  16. Thermal energy harvesting for large-scale applications using MWCNT-grafted glass fibers and polycarbonate-MWCNT nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Tzounis, L., E-mail: ltzounis@physics.auth.gr [Leibniz-Institut für Polymerforschung Dresden e.V., IPF, Hohe Str. 6, D-01069 Dresden (Germany); Technische Universität Dresden, Helmholtzstraße 10, 01069 Dresden (Germany); Laboratory for Thin Films-Nanosystems and Nanometrolo (Greece); Liebscher, M.; Stamm, M. [Leibniz-Institut für Polymerforschung Dresden e.V., IPF, Hohe Str. 6, D-01069 Dresden, Germany and Technische Universität Dresden, Helmholtzstraße 10, 01069 Dresden (Germany); Mäder, E.; Pötschke, P. [Leibniz-Institut für Polymerforschung Dresden e.V., IPF, Hohe Str. 6, D-01069 Dresden (Germany); Logothetidis, S., E-mail: logot@auth.gr [Laboratory for Thin Films-Nanosystems and Nanometrology (LTFN), Physics Department, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece)

    2015-02-17

    The thermoelectric properties of multi-wall carbon nanotube (MWCNT) -grafted glass fiber yarns (GF-CNT) and their epoxy model composites, as well as of polymer nanocomposites consisting of a polycarbonate (PC) matrix filled with differently functionalized MWCNTs have been examined. The GF-CNT hierarchical multi-scale structures were prepared by dip coating glass fiber yarns in a solution of carbonyl chloride modified MWCNTs; MWCNT-COCl (at a concentration of 0.5 mg/ml) under Ar atmosphere. The resulting GF-CNT exhibited high electrical conductivity (σ = 2.1×10{sup 3} S/m) due to the dense MWCNT deposited networks. The fiber surface morphology was investigated by scanning electron microscopy (SEM). The GF-CNT showed Seebeck coefficient (S); S = 16.8 μV/K, and power factor (P.F); P.F = 0.59 μW/mK−2. The high electrical conductivity of the GF-CNT is a key parameter for an optimum thermoelectric performance, since it can facilitate the flow of the thermally induced charge carriers upon being exposed to a temperature gradient. Polycarbonate/MWCNT nanocomposites were prepared by small-scale melt-mixing process using a microcompounder. Unfunctionalized, carboxyl (-COOH) and hydroxyl (-OH) modified MWCNTs were incorporated in PC at a constant amount of 2.5 wt.%, concentration above the electrical percolation threshold. The amount of MWCNTs was kept low to understand the fundamental aspects of their physical properties and their correlation to the composite morphology, as revealed by transmission electron microscopy (TEM). It was found that different functional groups can affect the thermoelectric performance and the conductivity of the nanocomposites. Namely, the highest Seebeck coefficient (S) was found for the composite containing carboxyl functionalized MWCNTs (11.3 μV/K), due to the highest oxygen content of MWCNTs proven by X-Ray Photoelectron spectroscopy (XPS). It is believed that MWCNT-grafted glass fibers as reinforcements in composite structural

  17. Surface aspects of discolouration in Bisphenol A Polycarbonate (BPA-PC), used as lens in LED-based products

    Science.gov (United States)

    Yazdan Mehr, M.; van Driel, W. D.; Udono, H.; Zhang, G. Q.

    2014-11-01

    The surface-related reactions during discolouration of Bisphenol A Polycarbonate (BPA-PC), used as LED lens plates, under thermal stress are studied. X-ray photoelectron spectroscopy (XPS) has been used to monitor the changes in the surface chemistry of BPA-PC plates over a temperature range of 100-140 °C for a period up to 3000 h. Increasing time under thermal stress is associated with the discolouration, and increase in the yellowing index (YI) of PC plastic lens. The XPS results show that discolouration is associated with oxidation at the surface, finding a significant increase in the signal ratio O1s/C1s in the XPS spectra of degraded specimens. During thermal ageing, the Csbnd H concentration decreases and new oxide features Cdbnd O and Osbnd Cdbnd O form, with the latter being a support for oxidation at the surface being a major reaction during discolouration. Results also show that irradiation with blue light during thermal ageing accelerates the kinetics of discolouration and the increased O1s/C1s ratio in XPS spectra.

  18. A novel room temperature-induced chemical etching (RTCE) technique for the enlargement of fission tracks in Lexan polycarbonate SSNTD

    International Nuclear Information System (INIS)

    Chavan, Vivek; Kalsi, P.C.; Manchanda, V.K.

    2011-01-01

    The chemical or electrochemical etching is an essential step to enlarge the ion-induced latent tracks in solid state nuclear track detectors (SSNTDs). In these methods, above ambient temperatures (∼60 o C) and moderately high concentrations of alkali are required for about 1-2 h to enlarge the latent tracks. Microwave induced chemical etching method is reported to reduce the etching time for alpha tracks from 3 to 4 h to 25 min for CR-39 detector. In the present work, a room temperature-induced chemical etching employing ethanolamine as a new etchant has been investigated for the first time to enlarge the fission tracks in Lexan polycarbonate SSNTD. The tracks developed in the Lexan detectors etched at room temperature using ethanolamine are compared with those etched with routinely used chemical etching (CE) technique in 6 N NaOH at 60 o C. The bulk etch and track etch rates are also reported. The detection efficiency of RTCE method is determined and compared with that of CE method. The RTCE technique is found to be simple, fast and convenient.

  19. Selection and fabrication of a non-woven polycarbonate urethane cover for a tissue engineered airway stent.

    Science.gov (United States)

    Chen, Weiluan; Clauser, Johanna; Thiebes, Anja Lena; McGrath, Donnacha J; McHugh, Peter E; Steinseifer, Ulrich; Jockenhoevel, Stefan; Hennink, Wim E; Kok, Robbert Jan

    2016-11-30

    One of the major problems in end-stage bronchotracheal cancer is stenosis of the upper airways, either due to luminal ingrowth of the tumor or mucus plugging. Airway stents that suppress tumor ingrowth and sustain mucociliary transport can alleviate these problems in end-stage bronchial cancer. We evaluated different types of polymeric covers for a tissue engineered airway stent. The distinguishing feature of this stent concept is that respiratory epithelial cells can grow on the luminal surface of the stent which facilitates mucociliary clearance. To facilitate growth of epithelial cells at the air-liquid interface of the stent, we developed a polyurethane cover that allows transport of nutrients to the cells. Nonwoven polycarbonate urethane (PCU) covers were prepared by a spraying process and evaluated for their porosity and glucose permeability. Respiratory epithelial cells harvested from sheep trachea were cultured onto the selected PCU cover and remained viable at the air-liquid interface when cultured for 21days. Lastly, we evaluated the radial force of a PCU-covered nitinol stent, and showed the PCU covers did not adversely affect the mechanical properties of the stents for their intended application in the smaller bronchi. These in vitro data corroborate the design of a novel airway stent for palliative treatment of bronchotracheal stenosis by combination of stent-technology with tissue-engineered epithelial cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Characterization and Processing Behavior of Heated Aluminum-Polycarbonate Composite Build Plates for the FDM Additive Manufacturing Process

    Directory of Open Access Journals (Sweden)

    Sherri L. Messimer

    2018-02-01

    Full Text Available One of the most essential components of the fused deposition modeling (FDM additive manufacturing (AM process is the build plate, the surface upon which the part is constructed. These are typically made from aluminum or glass, but there are clear disadvantages to both and restrictions on which materials can be processed on them successfully. This study examined the suitability of heated aluminum-polycarbonate (AL-PC composite print beds for FDM, looking particularly at the mechanical properties, thermal behavior, deformation behavior, bonding strength with deposited material, printing quality, and range of material usability. Theoretical examination and physical experiments were performed for each of these areas; the results were compared to similar experiments done using heated aluminum and aluminum-glass print beds. Ten distinct materials (ABS, PLA, PET, HIPS, PC, TPU, PVA, nylon, metal PLA, and carbon-fiber PLA were tested for printing performance. The use of a heated AL-PC print bed was found to be a practical option for most of the materials, particularly ABS and TPU, which are often challenging to process using traditional print bed types. Generally, the results were found to be equivalent to or superior to tempered glass and superior to standard aluminum build plates in terms of printing capability.

  1. Polymeric nanoparticles developed by vitamin E-modified aliphatic polycarbonate polymer to promote oral absorption of oleanolic acid

    Directory of Open Access Journals (Sweden)

    Wenjuan Zhang

    2017-11-01

    Full Text Available Oleanolic acid (OA exhibited good pharmacological activities in the clinical treatment of hypoglycemia, immune regulation, acute jaundice and chronic toxic hepatitis. However, the oral delivery of OA is greatly limited by its inferior water solubility and poor intestinal mucosa permeability. Herein, we developed a novel polymeric nanoparticle (NP delivery system based on vitamin E modified aliphatic polycarbonate (mPEG-PCC-VE to facilitate oral absorption of OA. OA encapsulated mPEG-PCC-VE NPs (OA/mPEG-PCC-VE NPs showed uniform particle size of about 170 nm with high drug loading capability (8.9%. Furthermore, the polymeric mPEG-PCC-VE NPs, with good colloidal stability and pH-sensitive drug release characteristics, significantly enhanced the in vitro dissolution of OA in the alkaline medium. The in situ single pass intestinal perfusion (SPIP studies performed on rats demonstrated that the OA/mPEG-PCC-VE NPs showed significantly improved permeability in the whole intestinal tract when compared to OA solution, especially for duodenum and colon. As a result, the in vivo pharmacokinetics study indicated that the bioavailability of OA/mPEG-PCC-VE NPs showed 1.5-fold higher than commercially available OA tablets. These results suggest that mPEG-PCC-VE NPs are a promising platform to facilitate the oral delivery of OA.

  2. 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.

  3. Evaluation of the release behavior of the dexamethasone embedded in polycarbonate polyurethane membranes: an in vitro study

    International Nuclear Information System (INIS)

    Kim, Dong Hyun; Kang, Sung Gwon; Lee, Chul Gab; Park, Sang Soo; Lee, Don Haeng; Lee, Gyu Baek; Song, Ho Young

    2003-01-01

    To evaluate the release behavior of dexamethasone embedded in a polycarbonate polyurethane membrane. Both water-soluble and water-insoluble dexamethasone were tested, and the release behavior of five water-insoluble dexamethasone films of different thickness (78 to 211 μm) was also evaluated. The amount of dexamethasone used was 10% of the total weight of the polyurethan film mass. Each film was placed in a centrifuge tube containing 25 ml of 0.1-M neutral phosphate buffer, and the tubes were placed in a shaking incubator to quantify the amount of drug released into the buffer, absorption spectroscopy (λ max=242 nm) was employed. In the test involving water-soluble dexamethasone, 60%, of the drug was released during the first two hours of the study. Films containing water-insoluble dexamethasone, on the other hand, released 40%, 60% and 75% of the dexamethasone in one, three and seven days, respectively. Both types of film maintained low-dose drug release for 28 days. When release behavior was compared between water-insoluble films of different thickness, thicker film showed less initial burst and more sustained release. Dexamethasone release behavior varies according to drug solubility and membrane thickness, and may thus be conrolled

  4. Synthesis and Characterization of Novel Polycarbonate Based Polyurethane/Polymer Wrapped Hydroxyapatite Nanocomposites: Mechanical Properties, Osteoconductivity and Biocompatibility.

    Science.gov (United States)

    Selvakumar, M; Jaganathan, Saravana Kumar; Nando, Golok B; Chattopadhyay, Santanu

    2015-02-01

    The present investigation reports the preparation of two types of 2D rod-like nano-hydroxyapatite (nHA) (unmodified and Polypropylene glycol (PPG) wrapped) of varying high-aspect ratios, by modified co-precipitation methods, without any templates. These nHA were successfully introduced into novel synthesized Thermoplastic Polyurethane (TPU) matrices based on polycarbonate soft segments, by both in-situ and ex-situ techniques. Physico-mechanical properties of the in-situ prepared TPU/nHA nanocomposites were found to be superior compared to the ex-situ counterparts, and pristine nHA reinforced TPU. Improved biocompatibility of the prepared nanocomposites was confirmed by MTT assays using osteoblast-like MG63 cells. Cell proliferation was evident over an extended period. Osteoconductivity of the nanocomposites was observed by successful formation of an apatite layer on the surface of the samples, after immersion into simulated body fluid (SBF). Prothrombin time (PT) and activated partial thromboplastin time (APTT), as calculated from coagulation assays, displayed an increase in the clotting time, particularly for the PPG-wrapped nHA nanocomposites, prepared through the in-situ technique. Only 0.3% of hemolysis was observed for the in-situ prepared nanocomposites, which establishes the antithrombotic property of the material. The key parameters for enhancing the technical properties and biocompatibility of the nanocomposites are: the interfacial adhesion parameter (B(σy)), the polymer-filler affinity, the aspect ratio of filler and non-covalent modifications, and the state of dispersion. Thus, the novel TPU/polymer wrapped nHA nanocomposites have great potential for biomedical applications, in particular for vascular prostheses, cardiovascular implants, scaffolds, and soft and hard tissues implants.

  5. Toward Plastic Smart Windows: Optimization of Indium Tin Oxide Electrodes for the Synthesis of Electrochromic Devices on Polycarbonate Substrates.

    Science.gov (United States)

    Laurenti, Marco; Bianco, Stefano; Castellino, Micaela; Garino, Nadia; Virga, Alessandro; Pirri, Candido F; Mandracci, Pietro

    2016-03-01

    Plastic smart windows are becoming one of the key elements in view of the fabrication of inexpensive, lightweight electrochromic (EC) devices to be integrated in the new generation of high-energy-efficiency buildings and automotive applications. However, fabricating electrochromic devices on polymer substrates requires a reduction of process temperature, so in this work we focus on the development of a completely room-temperature deposition process aimed at the preparation of ITO-coated polycarbonate (PC) structures acting as transparent and conductive plastic supports. Without providing any substrate heating or surface activation pretreatments of the polymer, different deposition conditions are used for growing indium tin oxide (ITO) thin films by the radiofrequency magnetron sputtering technique. According to the characterization results, the set of optimal deposition parameters is selected to deposit ITO electrodes having high optical transmittance in the visible range (∼90%) together with low sheet resistance (∼8 ohm/sq). The as-prepared ITO/PC structures are then successfully tested as conductive supports for the fabrication of plastic smart windows. To this purpose, tungsten trioxide thin films are deposited by the reactive sputtering technique on the ITO/PC structures, and the resulting single electrode EC devices are characterized by chronoamperometric experiments and cyclic voltammetry. The fast switching response between colored and bleached states, together with the stability and reversibility of their electrochromic behavior after several cycling tests, are considered to be representative of the high quality of the EC film but especially of the ITO electrode. Indeed, even if no adhesion promoters, additional surface activation pretreatments, or substrate heating were used to promote the mechanical adhesion among the electrode and the PC surface, the observed EC response confirmed that the developed materials can be successfully employed for the

  6. Use of UV-vis-NIR spectroscopy to monitor label-free interaction between molecular recognition elements and erythropoietin on a gold-coated polycarbonate platform.

    Science.gov (United States)

    Citartan, Marimuthu; Gopinath, Subash C B; Tominaga, Junji; Chen, Yeng; Tang, Thean-Hock

    2014-08-01

    Label-free-based detection is pivotal for real-time monitoring of biomolecular interactions and to eliminate the need for labeling with tags that can occupy important binding sites of biomolecules. One simplest form of label-free-based detection is ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy, which measure changes in reflectivity as a means to monitor immobilization and interaction of biomolecules with their corresponding partners. In biosensor development, the platform used for the biomolecular interaction should be suitable for different molecular recognition elements. In this study, gold (Au)-coated polycarbonate was used as a platform and as a proof-of-concept, erythropoietin (EPO), a doping substance widely abused by the athletes was used as the target. The interaction of EPO with its corresponding molecular recognition elements (anti-EPO monoclonal antibody and anti-EPO DNA aptamer) is monitored by UV-vis-NIR spectroscopy. Prior to this, to show that UV-vis-NIR spectroscopy is a suitable method for measuring biomolecular interaction, the interaction between biotin and streptavidin was demonstrated via this strategy and reflectivity of this interaction decreased by 25%. Subsequent to this, interaction of the EPO with anti-EPO monoclonal antibody and anti-EPO DNA aptamer resulted in the decrease of reflectivity by 5% and 10%, respectively. The results indicated that Au-coated polycarbonate could be an ideal biosensor platform for monitoring biomolecular interactions using UV-vis-NIR spectroscopy. A smaller version of the Au-coated polycarbonate substrates can be derived from the recent set-up, to be applied towards detecting EPO abuse among atheletes. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Applying graphene oxide nano-film over a polycarbonate nanoporous membrane to monitor E. coli by infrared spectroscopy.

    Science.gov (United States)

    Singh, Krishna Pal; Dhek, Neeraj Singh; Nehra, Anuj; Ahlawat, Sweeti; Puri, Anu

    2017-01-05

    Nano-biosensors are excellent monitoring tools for rapid, specific, sensitive, inexpensive, in-field, on-line, and/or real-time detection of pathogens in foods, soil, air, and water samples. A variety of nano-materials (metallic, polymeric, and/or carbon-based) were employed to enhance the efficacy, efficiency, and sensitivity of these nano-biosensors, including graphene-based materials, especially graphene oxide (GO)-based materials. GO bears many oxygen-bearing groups, enabling ligand conjugation at the high density critical for sensitive detection. We have fabricated GO-modified nano-porous polycarbonate track-etched (PCTE) membranes that were conjugated to an Escherichia coli-specific antibody (Ab) and used to detect E. coli. The random distribution of nanopores on the PCTE membrane surface and the bright coating of the GO onto the membrane were confirmed by scanning electron microscope. Anti-E. coli β-gal Abs were conjugated to the GO surface via 1-ethyl-3,3-dimethylaminopropyl carbodiimide hydrochloride-N-hydroxysuccinimide chemistry; antibody coating was confirmed by the presence of a characteristic IR peak near 1600cm(-1). A non-corresponding Ab (anti-Pseudomonas) was used as a negative control under identical conditions. When E. coli interacted anti-E.coli β-gal with Ab-coated GO-nano-biosensor units, we observed a clear shift in the IR peak from 3373.14 to 3315cm(-1); in contrast, we did not observe any shift in IR peaks when the GO unit was coated with the non-corresponding Ab (anti-Pseudomonas). Therefore, the detection of E. coli using the described GO-nano-sensor unit is highly specific, is highly selective and can be applied for real-time monitoring of E. coli with a detection limit between 100μg/mL and 10μg/mL, similar to existing detection systems. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Investigations of gamma irradiation on the properties of luminescent films of polycarbonate(PC) matrix doped with europium complex [Eu(tta)3(H2O)2

    International Nuclear Information System (INIS)

    Forster, Pedro L.; Lugao, Ademar B.; Martins, Natalia A.; Egute, Nayara S.; Parra, Duclerc F.; Brito, Hermi F.

    2009-01-01

    Luminescent lanthanide complexes have attracted much recent interest for their application as luminescent materials. The combination of unique spectroscopic properties from rare earth complexes associated to physical and chemical intrinsic properties of polymers became more attractive in the last years. A number of advantages of these substances have been reported or realized over the much studied conjugated polymers and nonlanthanide. Luminescent films composed by diaquatris(thenoyltrifluoroacetonate)europium(III) complex [Eu(tta) 3 (H 2 O) 2 ] doped into a polycarbonate (PC) matrix were prepared and irradiated at gamma radiation with 5, 10, and 20 kGy. The PC polymer was doped with 1% (w/w) of the Eu 3+ complex. The thermal properties was investigated by utilization of differential scanning calorimeter (DSC) changes in thermal stability was observed due to the addition of doping agent into the polycarbonate matrix. Changes in photophysical properties due of gamma radiation was observed by emission, excitation spectra and fourier transformed infrared spectra (FTIR). Based on the emission spectra of PC:1% Eu(tta)3 film were observed the characteristic bands arising from the 5 D 0 7 F J transitions of Eu 3+ ion (J=0-4), indicating the ability to obtain the luminescence films. (author)

  9. Probing the role of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) -coated multiwalled carbon nanotubes in the thermal and mechanical properties of polycarbonate nanocomposites

    KAUST Repository

    Zhou, Jian

    2014-03-05

    The role played by multiwalled carbon nanotubes (MWCNTs) coated with poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) in the thermal and mechanical properties of polycarbonate (PC) nanocomposites was analyzed. We used differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) to demonstrate that the glass transition temperature of polycarbonate nanocomposites decreased whereas the storage modulus of the samples increased by including PEDOT/PSS-coated MWCNTs. These results indicated that PEDOT/PSS acts as an antiplasticizer. We attributed the enhancement of the storage modulus to the strong hydrogen bonding between PSS and the PC matrix and the reduction of the free volume in the PC matrix due to the shrinkage of PEDOT/PSS upon heating. We also investigated changes in the thermal conductivity and thermal degradation behavior of the nanocomposites. The results indicated that PEDOT/PSS did not play a significant role in improving the thermal conductivity and thermal stability of PC nanocomposites. The relative improvements in the conductivity and thermal stability of the samples that contained PEDOT/PSS were attributed to the better dispersion of the MWCNTs in the PC matrix. © 2014 American Chemical Society.

  10. The Effects of the Cold Working Process and Interference Fit Bushings on the Fatigue Life of Polycarbonate Specimens with Holes

    National Research Council Canada - National Science Library

    Huelsman, Marc

    1997-01-01

    .... The most important performance factor is flight safety. In order to achieve flight safety from a structural standpoint, the transparency system must withstand loads associated with flight and with bird impact...

  11. Divergent Approach to a Family of Tyrosine-Derived Ru-Alkylidene Olefin Metathesis Catalysts.

    Science.gov (United States)

    Gleeson, Ellen C; Wang, Zhen J; Jackson, W Roy; Robinson, Andrea J

    2015-07-17

    A simple and generic approach to access a new family of Ru-alkylidene olefin metathesis catalysts with specialized properties is reported. This strategy utilizes a late stage, utilitarian Hoveyda-type ligand derived from tyrosine, which can be accessed via a multigram-scale synthesis. Further functionalization allows the catalyst properties to be tuned, giving access to modified second-generation Hoveyda-Grubbs-type catalysts. This divergent synthetic approach can be used to access solid-supported catalysts and catalysts that function under solvent-free and aqueous conditions.

  12. N-(jasmonoyl)tyrosine-derived compounds from flowers of broad beans (Vicia faba).

    Science.gov (United States)

    Kramell, Robert; Schmidt, Jürgen; Herrmann, Gabriele; Schliemann, Willibald

    2005-09-01

    Two new amide-linked conjugates of jasmonic acid, N-[(3R,7R)-(-)-jasmonoyl]-(S)-dopa (3) and N-[(3R,7R)-(-)-jasmonoyl]-dopamine (5), were isolated in addition to the known compound N-[(3R,7R)-(-)-jasmonoyl]-(S)-tyrosine (2) from the methanolic extract of flowers of broad bean (Vicia faba). Their structures were proposed on the basis of spectroscopic data (LC-MS/MS) and chromatographic properties on reversed and chiral phases and confirmed by partial syntheses. Furthermore, tyrosine conjugates of two cucurbic acid isomers (7, 8) were detected and characterized by LC-MS. Crude enzyme preparations from flowers of V. faba hydroxylated both (+/-)-2 and N-[(3R,7R/3S,7S)-(-)-jasmonoyl]tyramine [(+/-)-4] to (+/-)-3 and (+/-)-5, respectively, suggesting a possible biosynthetic relationship. In addition, a commercial tyrosinase (mushroom) and a tyrosinase-containing extract from hairy roots of red beet exhibited the same catalytic properties, but with different substrate specificities. The conjugates (+/-)-2, (+/-)-3, (+/-)-4, and (+/-)-5 exhibited in a bioassay low activity to elicit alkaloid formation in comparison to free (+/-)-jasmonic acid [(+/-)-1].

  13. Identification and quantification of the migration of chemicals from plastic baby bottles used as substitutes for polycarbonate.

    Science.gov (United States)

    Simoneau, C; Van den Eede, L; Valzacchi, S

    2012-01-01

    The results of a study on the analytical identification and quantification of migration of chemicals from plastics baby bottles found in the European Union market made of materials that are now present as substitutes for polycarbonate (PC) are reported. A total of 449 baby bottles with a focus on first age or sets of bottles were purchased from 26 European Union countries, Canada, Switzerland and the USA. From this collection, which contained several duplicates, a total of 277 baby bottles were analysed. The materials included different types of plastic such as PC, polyamide (PA), polyethersulphone (PES), polypropylene (PP), but also silicone, and from the United States a co-polyester marketed under the trade name Tritan™. The bottles were subjected to the conventional migration test for hot fill conditions, i.e. 2 h at 70°C. The simulant used was that specified in European Union legislation (2007/19/EC) for milk, i.e. 50% ethanol. In a first phase 1, migration was conducted since the scope of this investigation was a screening rather than a true compliance testing check. Second and third migrations were performed on selected articles when migrated substances exceeded limits specified in the legislation. In order to verify some materials, a portion of the bottle was cut to run an FT-IR fingerprint to confirm the nature of the polymer. The migration solutions in general showed a low release of substances. Results showed that bottles made of PP and silicones showed a greater number of substances in the migration solutions and in greater quantity. Chemicals from PP included alkanes, which could be found in >65% of the bottles at levels up to 3500 µg kg⁻¹; and benzene derivatives in 17% of the baby bottles and found at levels up to 113 µg kg⁻¹. Some substances were found on a regular basis such as plasticisers, esters and antioxidants (e.g. tris(2,4-di-tert-butylphenyl)phosphate, known as Irgafos 168. Some substances found were not included in the

  14. Effect of aligned carbon nanotubes on electrical conductivity ...

    Indian Academy of Sciences (India)

    continuing networks while direct current electric field only prevented agglomeration of the carbon nanotubes in the polycarbonate matrix and created relatively uniform distribution of nanotubes in the matrix. Keywords. Carbon nanotube; nanocomposite; electrical effect; magnetic effect. 1. Introduction. To reinforce materials ...

  15. Super-hydrophobic Silver-Doped TiO2 @ Polycarbonate Coatings Created on Various Material Substrates with Visible-Light Photocatalysis for Self-Cleaning Contaminant Degradation

    Science.gov (United States)

    Li, Zhengjian; Sun, Zongzhao; Duan, Zhiqiang; Li, Rui; Yang, Yanli; Wang, Jingyi; Lv, Xiaoxia; Qi, Wei; Wang, Hua

    2017-01-01

    In the present work, a facile and efficient fabrication method has been developed for creating super-hydrophobic coatings of silver-doped TiO2@polycarbonate (TiO2 (Ag)@PC) on the substrates of different materials with photocatalytic self-cleaning performances simply by the “dipping and drying” process. The substrates were first patterned with glue and then deposited with the dopamine-capped TiO2 (Ag)@PC (DA-TiO2 (Ag)@PC) nanocomposites, followed by the further etching with dimethylbenzene. The so prepared super-hydrophobic E-DA-TiO2(Ag)@PC coatings could present the lotus leaf-like porous architectures, high adhesion stability, and especially the visible-light photocatalysis for organic contaminant degradation, thus promising the wide outdoor and indoor applications like water proofing, metal erosion protection, and surface self-cleaning. PMID:28218285

  16. Combined FDTD-Monte Carlo analysis and a novel design for ZnO scintillator rods in polycarbonate membrane for X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadian-Behbahani, Mohammad-Reza [Department of Energy Engineering and Physics, Amir-Kabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of); Saramad, Shahyar, E-mail: ssaramad@aut.ac.ir [Department of Energy Engineering and Physics, Amir-Kabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of); Mohammadi, Mohammad [Department of Electrical Engineering, Amir-Kabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of)

    2017-05-01

    A combination of Finite Difference Time Domain (FDTD) and Monte Carlo (MC) methods is proposed for simulation and analysis of ZnO microscintillators grown in polycarbonate membrane. A planar 10 keV X-ray source irradiating the detector is simulated by MC method, which provides the amount of absorbed X-ray energy in the assembly. The transport of generated UV scintillation light and its propagation in the detector was studied by the FDTD method. Detector responses to different probable scintillation sites and under different energies of X-ray source from 10 to 25 keV are reported. Finally, the tapered geometry for the scintillators is proposed, which shows enhanced spatial resolution in comparison to cylindrical geometry for imaging applications.

  17. High-throughput determination of quantitative structure-property relationships using a resonant multisensor system: solvent resistance of bisphenol a polycarbonate copolymers.

    Science.gov (United States)

    Potyrailo, Radislav A; McCloskey, Patrick J; Wroczynski, Ronald J; Morris, William G

    2006-05-01

    Polymers are important materials for sensor, microfluidic, and other demanding applications. High-throughput screening methodology has been applied for the evaluation of the solvent resistance of a family of polycarbonate copolymers prepared from the reaction of bisphenol A (BPA), hydroquinone (HQ), and resorcinol (RS) in different solvents of practical importance, such as chloroform, tetrahydrofuran (THF), and methyl ethyl ketone (MEK). We employed a 24-channel acoustic-wave sensor system that provided previously unavailable capabilities for parallel evaluation of polymer solvent resistance. This high-throughput polymer evaluation approach assisted in construction of detailed solvent-resistance maps of polycarbonate copolymers and in determination of quantitative structure-property relationships. The best absolute solvent resistance of all studied copolymers was achieved in MEK, followed by chloroform and THF. A D-optimal mixture design was employed to explore the relationship between the copolymer compositions and their solvent resistance. The applied special cubic model for each solvent took into account the primary mixture terms such as BPA, HQ, and RS; binary interaction terms such as BPA-HQ, BPA-RS, and HQ-RS; and a ternary interaction term BPA-HQ-RS. A combination of the normal distribution of the model residuals and the very high values of adjusted R2 (0.97-0.99) demonstrated a good quality of the model. At a HQ concentration of 40 mol %, the solvent resistance was the highest for all tested solvents, and different concentrations of BPA (40 and 60 mol %) and RS (0 and 20 mol %) did not affect the solvent resistance. Without HQ, solvent resistance was decreasing with an increase of RS and decrease of BPA. Overall, with an increase of HQ concentration from 0 to 40 mol %, the solvent resistance of BPA-HQ-RS copolymers was improved by up to 3 times in THF, by 21 times in chloroform, and by 32 times in MEK.

  18. Areal density effects on the blocking of 3-keV Ne7+ ions guided through nanocapillaries in polymers

    NARCIS (Netherlands)

    Stolterfoht, N.; Hellhammer, R.; Sulik, B.; Juhasz, Z.; Bayer, V.; Trautmann, C.; Bodewits, E.; Reitsma, G.; Hoekstra, R.

    2013-01-01

    We studied blocking effects on ion guiding through nanocapillaries in highly insulating polyethylene terephthalate (PET). The experiments were initiated in view of a previous study with capillaries in polycarbonate (PC) for which strong blocking effects were observed, whereas for PET these effects

  19. Conformal SiO2 coating of sub-100 nm diameter channels of polycarbonate etched ion-track channels by atomic layer deposition

    Directory of Open Access Journals (Sweden)

    Nicolas Sobel

    2015-02-01

    Full Text Available Polycarbonate etched ion-track membranes with about 30 µm long and 50 nm wide cylindrical channels were conformally coated with SiO2 by atomic layer deposition (ALD. The process was performed at 50 °C to avoid thermal damage to the polymer membrane. Analysis of the coated membranes by small angle X-ray scattering (SAXS reveals a homogeneous, conformal layer of SiO2 in the channels at a deposition rate of 1.7–1.8 Å per ALD cycle. Characterization by infrared and X-ray photoelectron spectroscopy (XPS confirms the stoichiometric composition of the SiO2 films. Detailed XPS analysis reveals that the mechanism of SiO2 formation is based on subsurface crystal growth. By dissolving the polymer, the silica nanotubes are released from the ion-track membrane. The thickness of the tube wall is well controlled by the ALD process. Because the track-etched channels exhibited diameters in the range of nanometres and lengths in the range of micrometres, cylindrical tubes with an aspect ratio as large as 3000 have been produced.

  20. Measurement of ion beam angular distribution at different helium gas pressures in a plasma focus device by large-area polycarbonate detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sohrabi, M.; Habibi, M., E-mail: mortezahabibi@gmail.com; Ramezani, V. [Amirkabir University of Technology, Energy Engineering and Physics Department (Iran, Islamic Republic of)

    2017-02-15

    The paper presents an experimental study and analysis of full helium ion density angular distributions in a 4-kJ plasma focus device (PFD) at pressures of 10, 15, 25, and 30 mbar using large-area polycarbonate track detectors (PCTDs) (15-cm etchable diameter) processed by 50-Hz-HV electrochemical etching (ECE). Helium ion track distributions at different pressures, in particular, at the main axis of the PFD are presented. Maximum ion track density of ~4.4 × 10{sup 4} tracks/cm{sup 2} was obtained in the PCTD placed 6 cm from the anode. The ion distributions for all pressures applied are ring-shaped, which is possibly due to the hollow cylindrical copper anode used. The large-area PCTD processed by ECE proves, at the present state-of-theart, a superior method for direct observation and analysis of ion distributions at a glance with minimum efforts and time. Some observations of the ion density distributions at different pressures are reported and discussed.

  1. Thermal conductivity and stability of a three-phase blend of carbon nanotubes, conductive polymer, and silver nanoparticles incorporated into polycarbonate nanocomposites

    KAUST Repository

    Patole, Archana

    2015-04-16

    Metallic and non-metallic nanofillers can be used together in the design of polycarbonate (PC) nanocomposites with improved electrical properties. Here, the preparation of three-phase blend (carbon nanotubes (CNT), silver nanoparticles, and conductive polymer) in a two-step process before incorporation in the PC is reported. First, ethylene diamine functionalized multiwall carbon nanotubes (MWCNT-EDA) were decorated with Ag nanoparticles. Next, the Ag-decorated CNTs were coated with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). Due to the high thermal conductivity instrinsic to both metallic and non-metallic phases, it is expected that the thermal properties of the resulting nanocomposite would largely differ from those of pristine PC. We thus investigated in detail how this hybrid conductive blend affected properties such as the glass transition temperature, the thermal stability, and the thermal conductivity of the nanocomposite. It was found that this strategy results in improved thermal conductivity and thermal stability of the material. © 2015 Wiley Periodicals, Inc.

  2. Optimization of mass spectrometry acquisition parameters for determination of polycarbonate additives, degradation products, and colorants migrating from food contact materials to chocolate.

    Science.gov (United States)

    Bignardi, Chiara; Cavazza, Antonella; Laganà, Carmen; Salvadeo, Paola; Corradini, Claudio

    2018-01-01

    The interest towards "substances of emerging concerns" referred to objects intended to come into contact with food is recently growing. Such substances can be found in traces in simulants and in food products put in contact with plastic materials. In this context, it is important to set up analytical systems characterized by high sensitivity and to improve detection parameters to enhance signals. This work was aimed at optimizing a method based on UHPLC coupled to high resolution mass spectrometry to quantify the most common plastic additives, and able to detect the presence of polymers degradation products and coloring agents migrating from plastic re-usable containers. The optimization of mass spectrometric parameter settings for quantitative analysis of additives has been achieved by a chemometric approach, using a full factorial and d-optimal experimental designs, allowing to evaluate possible interactions between the investigated parameters. Results showed that the optimized method was characterized by improved features in terms of sensitivity respect to existing methods and was successfully applied to the analysis of a complex model food system such as chocolate put in contact with 14 polycarbonate tableware samples. A new procedure for sample pre-treatment was carried out and validated, showing high reliability. Results reported, for the first time, the presence of several molecules migrating to chocolate, in particular belonging to plastic additives, such Cyasorb UV5411, Tinuvin 234, Uvitex OB, and oligomers, whose amount was found to be correlated to age and degree of damage of the containers. Copyright © 2017 John Wiley & Sons, Ltd.

  3. A strategy for achieving low percolation and high electrical conductivity in melt-blended polycarbonate (PC/multiwall carbon nanotube (MWCNT nanocomposites: Electrical and thermo-mechanical properties

    Directory of Open Access Journals (Sweden)

    B. B. Khatua

    2013-06-01

    Full Text Available In this work, polycarbonate (PC/multiwall carbon nanotube (MWCNT nanocomposites were prepared by simple melt mixing at a temperature (~350°C well above the processing temperature of PC, followed by compression molding, that exhibited percolation threshold as low as of 0.11 wt% and high electrical conductivity of 1.38x10–3 S•cm–1 at only 0.5 wt% MWCNT loading. Due to the lower interfacial energy between MWCNT and PC, the carbon nanotubes are excellently dispersed and formed continuous conductive network structure throughout the host polymer. AC electrical conductivity and dielectric permittivity of PC/MWCNT nanocomposites were characterized in a broad frequency range, 101–107 Hz. Low percolation threshold (pc of 0.11 wt% and the critical exponent (t of ~3.38 was resulted from scaling law equation. The linear plot of logσDC vs. p–1/3 supported the presence of tunneling conduction among MWCNTs. The thermal property and storage modulus of PC were increased with the incorporation of little amount of MWCNTs. Transmission electron microscopy (TEM and field emission scanning electron microscopy (FESEM confirmed the homogeneous dispersion and distribution of MWCNTs throughout the matrix phase.

  4. Structure-properties relationships of novel poly(carbonate-co-amide) segmented copolymers with polyamide-6 as hard segments and polycarbonate as soft segments

    Science.gov (United States)

    Yang, Yunyun; Kong, Weibo; Yuan, Ye; Zhou, Changlin; Cai, Xufu

    2018-04-01

    Novel poly(carbonate-co-amide) (PCA) block copolymers are prepared with polycarbonate diol (PCD) as soft segments, polyamide-6 (PA6) as hard segments and 4,4'-diphenylmethane diisocyanate (MDI) as coupling agent through reactive processing. The reactive processing strategy is eco-friendly and resolve the incompatibility between polyamide segments and PCD segments in preparation processing. The chemical structure, crystalline properties, thermal properties, mechanical properties and water resistance were extensively studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Thermal gravity analysis (TGA), Dynamic mechanical analysis (DMA), tensile testing, water contact angle and water absorption, respectively. The as-prepared PCAs exhibit obvious microphase separation between the crystalline hard PA6 phase and amorphous PCD soft segments. Meanwhile, PCAs showed outstanding mechanical with the maximum tensile strength of 46.3 MPa and elongation at break of 909%. The contact angle and water absorption results indicate that PCAs demonstrate outstanding water resistance even though possess the hydrophilic surfaces. The TGA measurements prove that the thermal stability of PCA can satisfy the requirement of multiple-processing without decomposition.

  5. Improved permeation performance and fouling-resistance of Poly(vinyl chloride/Polycarbonate blend membrane with added Pluronic F127

    Directory of Open Access Journals (Sweden)

    Supateekan Pacharasakoolchai

    2014-04-01

    Full Text Available The aim of this work was to prepare and characterize poly(vinyl chloride (PVC/polycarbonate (PC blend membranes for use in ultrafiltration. Pluronic F127 was used as an additive to modify the membrane surface of the PVC/PC blended membranes. The PVC/PC blend membrane was first prepared using the phase inversion method from a casting solution of PVC with small amount of PC in N-methylpyrrolidone (NMP and water as the non-solvent. The morphologies structure and properties, such as tensile strength, water flux, and bovine serum albumin (BSA rejection of the blend membrane were studied. Increased amounts of PC resulted in an increase in the water flux and ability to reject protein. A concentration of 0.75 wt% PC provided the best improvement in tensile strength of blend membrane. Addition of different amounts of pluronic F127 to the casting solution of PVC/PC with a PC concentration of 0.75 wt% resulted in a decrease in the water contact angle that demonstrated the improvement of hydrophilicity of blend membrane. Scanning electron microscopy photographs showed that the modified PVC/PC membranes had a bigger pore volume in the porous sub-layer compared to the PVC/PC control membrane. The PVC/PC membrane with added Pluronic F127 exhibited a much higher flux and rejection of BSA in a protein filtration experiment than the PVC/PC membrane. An increase in flux recovery ratio of PVC/PC/pluronic 127 blend membrane indicated that the modified membranes could reduce membrane fouling useful for ultrafiltration.

  6. Fast and simple determination and exposure assessment of bisphenol A, phenol, p-tert-butylphenol, and diphenylcarbonate transferred from polycarbonate food-contact materials to food simulants.

    Science.gov (United States)

    Park, So-Ra; Park, Se-Jong; Jeong, Mi-Jin; Choi, Jae Chun; Kim, MeeKyung

    2018-03-29

    Polycarbonate (PC) plastics find extensive use in baby bottles, food storage containers, and various kitchen items. Possibly hazardous chemicals, bisphenol A (BPA), phenol, p-tert-butylphenol (TBP), and diphenylcarbonate (DPC), are source materials or by-products from PC production. Therefore, a fast and simple analytical method was developed to determine and assess the exposure of BPA, phenol, TBP, and DPC transferred from PC food-contact materials to four different food simulants (water, 4% acetic acid, 50% ethanol, and n-heptane) at different temperatures. The method was validated in terms of limit of detection (LOD) and quantification (LOQ), recovery, and precision for the detection of BPA, phenol, and TBP using HPLC-FLD and of DPC using HPLC-UV. BPA, phenol, TBP, and DPC concentrations transferred from 200 PC samples to food simulants were determined. The highest migration levels of BPA (54.3 μg L -1 ) and phenol (43.8 μg L -1 ) were found in 50% ethanol at 70 °C. TBP did not migrate to any simulant. DPC did not show any migration from PC samples into water and only migrated from a cup to 4% acetic acid at 70 °C and 100 °C, whereas migration occurred from several cups, ladles, spoons, and tongs to 50% ethanol and to n-heptane at 25 °C. Food simulants and temperature were the crucial factors for the migration of BPA and phenol from PC samples. Estimated daily intakes (EDIs), based on food consumption and food-type distribution factors, for BPA, phenol, and DPC were calculated to be 0.007, 0.001, and 2.5 × 10 -4  μg kg -1 bw day -1 , respectively. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. PRELIMINARILY DEVELOPMENT OF A MOISTURE-ACTIVATED BIORESORBABLE POLYMERIC PLATFORM FOR DRUG DELIVERY

    Directory of Open Access Journals (Sweden)

    Renê O. do Couto

    2015-08-01

    Full Text Available Bioresorbable polymeric films were prepared by solvent casting using a tyrosine-derived polycarbonate and metronidazole (MDZ as the model drug at 2.5%, 5% and 10% (w/w. Drug loading did not affect the water uptake, drug release, polymer degradation or erosion profiles. All devices released approximately 85% (w/w of the drug within a 1.5 h period. This may be attributed to the rapid water uptake of the polymer. An increase in the water uptake correlated with a linear rate increase of the polymer degradation (0.968 ≤ R2 ≤ 0.999. Moreover, MDZ presented a remarkable plasticizing effect for the polymer and drug loading exerted a significant impact on the mechanical properties of the obtained films. The results obtained can be used to further the development of novel biocompatible and biodegradable polymeric platforms for the delivery of metronidazole and other drugs in a broad range of pharmaceutical applications.

  8. A low-cost, high-efficiency and high-flexibility surface modification technology for a black bisphenol A polycarbonate board

    Science.gov (United States)

    Wang, Suhuan; Liu, Jianguo; Lv, Ming; Zeng, Xiaoyan

    2014-09-01

    In this paper, a low-cost, high-efficiency and high-flexibility surface modification technology for polymer materials was achieved at high laser scanning speeds (600-1000 mm s-1) and using an all-solid state, Q-switched, high-average power, and nanosecond pulse ultraviolet (355 nm wavelength) laser. During the surface modification of a very important engineering plastic, i.e., black bisphenol A polycarbonate (BAPC) board, it was found that different laser parameters (e.g., laser fluence and pulse frequency) were able to result in different surface microstructures (e.g., many tiny protuberances or a porous microstructure with periodical V-type grooves). After the modification, although the total relative content of the oxygen-containing groups (e.g., Csbnd O and COO-) on the BAPC surface increased, however, the special microstructures played a deciding role in the surface properties (e.g., contact angle and surface energy) of the BAPC. The change trend of the water contact angle on the BAPC surface was with an obvious increase, that of the diiodomethane contact angle was with a most decrease, and that of the ethylene glycol contact angle was between the above two. It showed that the wetting properties of the three liquids on the modified BAPC surface were different. Basing on the measurements of the contact angles of the three liquids, and according to the Young equation and the Lifshitz van der Waals and Lewis acid-base theory, the BAPC surface energy after the modification was calculated. The results were that, in a broad range of laser fluences, pulse frequencies and scanning speeds, the surface energy had a significant increase (e.g., from the original of about 44 mJ m-2 to the maximum of about 70 mJ m-2), and the higher the laser pulse frequency, the more significant the increase. This would be very advantageous to fabricate the high-quality micro-devices and micro-systems on the modified surface.

  9. Use of laser-induced breakdown spectroscopy for the determination of polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) concentrations in PC/ABS plastics from e-waste.

    Science.gov (United States)

    Costa, Vinicius Câmara; Aquino, Francisco Wendel Batista; Paranhos, Caio Marcio; Pereira-Filho, Edenir Rodrigues

    2017-12-01

    Due to the continual increase in waste generated from electronic devices, the management of plastics, which represents between 10 and 30% by weight of waste electrical and electronic equipment (WEEE or e-waste), becomes indispensable in terms of environmental and economic impacts. Considering the importance of acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), and their blends in the electronics and other industries, this study presents a new application of laser-induced breakdown spectroscopy (LIBS) for the fast and direct determination of PC and ABS concentrations in blends of these plastics obtained from samples of e-waste. From the LIBS spectra acquired for the PC/ABS blend, multivariate calibration models were built using partial least squares (PLS) regression. In general, it was possible to infer that the relative errors between the theoretical or reference and predicted values for the spiked samples were lower than 10%. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Effect of Reprocessing and Accelerated Weathering on Impact-Modified Recycled Blend

    Science.gov (United States)

    Ramesh, V.; Mohanty, Smita; Biswal, Manoranjan; Nayak, Sanjay K.

    2015-12-01

    Recovery of recycled polycarbonate, acrylonitrile butadiene styrene, high-impact polystyrene, and its blends from waste electrical and electronic equipment plastics products properties were enhanced by the addition of virgin polycarbonate and impact modifier. The optimized blend formulation was processed through five cycles, at processing temperature, 220-240 °C and accelerated weathering up to 700 h. Moreover, the effect of reprocessing and accelerated weathering in the physical properties of the modified blends was investigated by mechanical, thermal, rheological, and morphological studies. The results show that in each reprocessing cycle, the tensile strength and impact strength decreased significantly and the similar behavior has been observed from accelerated weathering. Subsequently, the viscosity decreases and this decrease becomes the effect of thermal and photo-oxidative degradation. This can be correlated with FTIR analysis.

  11. Effects of natural organic compounds on adsorption of actinoid on solid phase and interaction between colloid

    Energy Technology Data Exchange (ETDEWEB)

    Tominaga, Takeshi; Minai, Yoshitaka; Takahashi, Yoshio; Kohashi, Asaya [Tokyo Univ. (Japan); Yoshida, Zenko; Meguro, Yoshihiro; Kimura, Takaumi

    1996-01-01

    Two problems were studied such as, at first, the effects of calcium and magnesium on formation of complex of actinoid (III) and humic acid and, second, estimation of number of hydrate of europium (III) in polycarbonic acid complex by fluorescence lifetime measurements. With adding calcium and magnesium, the solubility of humic acid and apparent complex formation constant of actinoid (III)-humic acid complex decreased and amount of adsorption of humic acid on kaolinite increased. Apparent complex formation constant increased with increasing the dissociation degree but decreased with increasing the concentration of supporting electrolyte as same as that of humic acid. This result can be explained by the model of polymer electrolyte on the static electrical interaction with metal ions, because polycarbonic acid is polymer electrolyte with many dissociation groups in a molecule. (S.Y.)

  12. A novel method for observation by unaided eyes of nitrogen ion tracks and angular distribution in a plasma focus device using 50 Hz–HV electrochemically-etched polycarbonate detectors

    International Nuclear Information System (INIS)

    Sohrabi, M.; Habibi, M.; Roshani, G.H.; Ramezani, V.

    2012-01-01

    A novel ion detection method has been developed and studied in this paper for the first time to detect and observe tracks of nitrogen ions and their angular distribution by unaided eyes in the Amirkabir 4 kJ plasma focus device (PFD). The method is based on electrochemical etching (ECE) of nitrogen ion tracks in 1 mm thick large area polycarbonate (PC) detectors. The ECE method employed a specially designed and constructed large area ECE chamber by applying a 50 Hz–high voltage (HV) generator under optimized ECE conditions. The nitrogen ion tracks and angular distribution were efficiently (constructed for this study) amplified to a point observable by the unaided eyes. The beam profile and angular distribution of nitrogen ion tracks in the central axes of the beam and two- and three-dimensional iso-ion track density distributions showing micro-beam spots were determined. The distribution of ion track density along the central axes versus angular position shows double humps around a dip at the 0° angular positions. The method introduced in this paper proved to be quite efficient for ion beam profile and characteristic studies in PFDs with potential for ion detection studies and other relevant dosimetry applications.

  13. Study of physico-chemical release of uranium and plutonium oxides during the combustion of polycarbonate and of ruthenium during the combustion of solvents used in the reprocessing of nuclear fuel

    International Nuclear Information System (INIS)

    Bouilloux, L.

    1998-01-01

    The level of consequences concerning a fire in a nuclear facility is in part estimated by the quantities and the physico-chemical forms of radioactive compounds that may be emitted out of the facility. It is therefore necessary to study the contaminant release from the fire. Because of the multiplicity of the scenarios, two research subjects were retained. The first one concerns the study of the uranium or plutonium oxides chemical release during the combustion of the polycarbonate glove box sides. The second one is about the physico chemical characterisation of the ruthenium release during the combustion of an organic solvent mixture (tributyl phosphate-dodecane) used for the nuclear fuel reprocessing. Concerning the two research subjects, the chemical release, i.e. means the generation of contaminant compounds gaseous in the fire, was modelled using thermodynamical simulations. Experiments were done in order to determine the ruthenium release factor during solvent combustion. A cone calorimeter was used for small scale experiments. These results were then validated by large scale tests under conditions close to the industrial process. Thermodynamical simulations, for the two scenarios studied. Furthermore, the experiments on solvent combustion allowed the determination of a suitable ruthenium release factor. Finally, the mechanism responsible of the ruthenium release has been found. (author)

  14. Study of physico-chemical release of uranium and plutonium oxides during the combustion of polycarbonate and of ruthenium during the combustion of solvents used in the reprocessing of nuclear fuel; Etude de la mise en suspension physico-chimique des oxydes de plutonium et d'uranium lors de la combustion de polycarbonate et de ruthenium lors de la combustion des solvants de retraitement du combustible irradie

    Energy Technology Data Exchange (ETDEWEB)

    Bouilloux, L

    1998-07-01

    The level of consequences concerning a fire in a nuclear facility is in part estimated by the quantities and the physico-chemical forms of radioactive compounds that may be emitted out of the facility. It is therefore necessary to study the contaminant release from the fire. Because of the multiplicity of the scenarios, two research subjects were retained. The first one concerns the study of the uranium or plutonium oxides chemical release during the combustion of the polycarbonate glove box sides. The second one is about the physico chemical characterisation of the ruthenium release during the combustion of an organic solvent mixture (tributyl phosphate-dodecane) used for the nuclear fuel reprocessing. Concerning the two research subjects, the chemical release, i.e. means the generation of contaminant compounds gaseous in the fire, was modelled using thermodynamical simulations. Experiments were done in order to determine the ruthenium release factor during solvent combustion. A cone calorimeter was used for small scale experiments. These results were then validated by large scale tests under conditions close to the industrial process. Thermodynamical simulations, for the two scenarios studied. Furthermore, the experiments on solvent combustion allowed the determination of a suitable ruthenium release factor. Finally, the mechanism responsible of the ruthenium release has been found. (author)

  15. Effect of thermal shock on mechanical properties of injection-molded thermoplastic denture base resins.

    Science.gov (United States)

    Takahashi, Yutaka; Hamanaka, Ippei; Shimizu, Hiroshi

    2012-07-01

    This study investigated the effect of thermal shock on the mechanical properties of injection-molded thermoplastic denture base resins. Four thermoplastic resins (two polyamides, one polyethylene terephthalate, one polycarbonate) and, as a control, a conventional heat-polymerized polymethyl methacrylate (PMMA), were tested. Specimens of each denture base material were fabricated according to ISO 1567 and were either thermocycled or not thermocycled (n = 10). The flexural strength at the proportional limit (FS-PL), the elastic modulus and the Charpy impact strength of the denture base materials were estimated. Thermocycling significantly decreased the FS-PL of one of the polyamides and the PMMA and it significantly increased the FS-PL of one of the polyamides. In addition, thermocycling significantly decreased the elastic modulus of one of the polyamides and significantly increased the elastic moduli of one of the polyamides, the polyethylene terephthalate, polycarbonate and PMMA. Thermocycling significantly decreased the impact strength of one of the polyamides and the polycarbonate. The mechanical properties of injection-molded thermoplastic denture base resins changed after themocycling.

  16. Effect of nightguard vital bleaching gel on the color stability of provisional restorative materials.

    Science.gov (United States)

    Bajunaid, Salwa Omar

    2016-01-01

    To assess the hypothesis that there was no difference in effect of 10% and 15% tooth bleaching agents on color stability of materials used for provisional fixed dental prosthesis. Fifteen samples from two materials used for provisional fixed dental prosthesis: methacrylate-based and composite-based materials and 15 preformed polycarbonate crowns soaked in bleaching gel or distilled water. Spectrophotometer recorded color of specimens at baseline, after 3, 7, and 14 days. Data were statistically analyzed using two-factor ANOVA test to compare the color stability of tested materials. Methyl-based provisional material exhibited statistically higher color change when exposed to 10% and 15% bleaching gel (delta EFNx01: 9.0 and 11.1, respectively) as compared to distilled water (delta EFNx01: 2.9). Delta EFNx01 of composite-based material specimens exposed to distilled water was statistically higher (6.3) than specimens exposed to 10% and 15% bleaching gel (1.5 and 1.1, respectively). Polycarbonate crowns showed a statistically lower color change when exposed to 15% (0.9) than to 10% bleaching gel (5.1) or distilled water (5.5). Composite-based provisional material showed highest color stability when exposed to vital tooth bleaching gel, whereas methacrylate-based material was the least color stable. Polycarbonate crowns were more color stable when exposed to 15% bleaching gel as opposed to 10% bleaching gel.

  17. Espectro Vibracional no Infravermelho Próximo dos Polímeros Poliestireno, Poli(Metacrilato de Metila e Policarbonato Near-Infrared Spectra of Polystyrene, Poly(Methyl Methacrylate and Polycarbonate

    Directory of Open Access Journals (Sweden)

    Sérgio C. de Araújo

    2001-01-01

    Full Text Available Os espectros no infravermelho próximo (NIR dos polímeros amorfos poliestireno (PS, poli(metacrilato de metila (PMMA e policarbonato (PC foram estudados. A tentativa de atribuição das bandas harmônicas e de combinação dos modos vibracionais do PS, PMMA e PC foi realizada baseando-se na teoria de modos locais e pelo uso do método matemático de ajuste de curvas. A correção de anarmonicidade e freqüência mecânica foi determinada em um gráfico de Birge-Sponer. Uma correção de anarmonicidade de 57 e 58 cm-1 foi obtida para os modos de estiramento dos grupos CH2 e CH do PS; 59 e 9 cm-1 para os modos de estiramento dos grupos CH3 e CO do PMMA e 53, 59 e 10 cm-1 para os modos de estiramento dos grupos CH, CH3 e CO do PC, respectivamente.The near-infrared (NIR spectra of the amorphous polymers polystyrene (PS, poly(methyl methacrylate (PMMA, and polycarbonate (PC have been studied. The tentative assignment of the overtone and combination frequencies is made using the curve fitting calculations and the local mode theory. Anharmonicity correction and mechanical frequency were determined from a Birge-Sponer plot. A tentative assignment of stretch overtone frequency of CH2 and CH functional groups of PS; CH3 and CO functional groups of PMMA and CH, CH3 and CO functional groups of PC has been made. An anharmonicity correction of 57 and 58 cm-1 was obtained for CH2 and CH stretch modes of PS; 59 and 9 cm-1 for CH3 and CO stretch modes of PMMA and 53, 59 and 10 cm-1 for CH, CH3 and CO stretch modes of PC, respectively.

  18. Mistura reativa de poliamida 6 e policarbonato: reatividade do copolímero formado "in situ" Polyamide 6 and polycarbonate reactive blends: reactivity of the copolymer formed "in situ"

    Directory of Open Access Journals (Sweden)

    Dilma A. Costa

    2004-01-01

    Full Text Available As misturas físicas de poliamida 6 (PA6 e policarbonato (PC processadas a 240 ºC, durante 10, 30 e 60 minutos formam um copolímero de PA6-PC. A alta temperatura e o longo tempo de processamento podem causar modificações nas propriedades dessas misturas e degradar o copolímero, originando grupos isocianato e subseqüentemente CO2 e grupos NH2 terminais. A quantidade de copolímero PA6-PC formado durante o processo de mistura é maior com o aumento da proporção de PC na mistura. As ligações uretânicas de polímeros termoplásticos exibem mais baixas estabilidades térmica e oxidativa, resultando no aumento da concentração de grupos terminais NH2. A reatividade dessas misturas foi investigada através do torque durante o processo de mistura, da titulação potenciométrica dos grupos NH2 terminais e por microscopia eletrônica de varredura.Polyamide 6 (PA6 and polycarbonate (PC blends processed at 240 °C, during 10, 30 and 60 minutes produced a copolymer of PA6-PC. The high temperature and long processing time can cause modifications on the properties of these blends and degradation of the copolymer. It can also form isocyanate groups and subsequently CO2 and NH2 "end groups". The amount of PA6-PC copolymer formed during the blending process was found to increase when the PC content is increased. The thermoplastic urethanes normally exhibit smaller thermal and oxidative stability, resulting in an increase in the concentration of NH2 terminal groups. The reactivity of the blends was investigated by monitoring the torque during the blending, potentiometer titration of NH2 terminal groups and scanning electronic microscopy (SEM.

  19. Simulation of radiation effects in ultra-thin insulating layers

    Directory of Open Access Journals (Sweden)

    Timotijević Ljubinko B.

    2013-01-01

    Full Text Available The Monte Carlo simulations of charged particle transport are used to investigate the effects of exposing ultra-thin layers of insulators (commonly used in integrated circuits to beams of protons, alpha particles and heavy ions. Materials considered include silicon dioxide, aluminum nitride, alumina, and polycarbonate - lexan. The parameters that have been varied in simulations include the energy of incident charged particles and insulating layer thickness. Materials are compared according to both ionizing and non-ionizing effects produced by the passage of radiation. [Projekat Ministarstva nauke Republike Srbije, br. 171007

  20. 21 CFR 177.1580 - Polycarbonate resins.

    Science.gov (United States)

    2010-04-01

    ... condensation of 4,4′-iso-propylidenediphenol and carbonyl chloride to which may have been added certain optional adjuvant substances required in the production of the resins; or by (2) The reaction of molten 4,4′-iso-propylidenediphenol with molten diphenyl carbonate in the presence of the disodium salt of 4,4...

  1. Molecular Design and Evaluation of Biodegradable Polymers Using a Statistical Approach

    Science.gov (United States)

    Lewitus, Dan; Rios, Fabian; Rojas, Ramiro; Kohn, Joachim

    2013-01-01

    The challenging paradigm of bioresorbable polymers, whether in drug delivery or tissue engineering, states that a fine-tuning of the interplay between polymer properties (e.g., thermal, degradation), and the degree of cell/tissue replacement and remodeling is required. In this paper we describe how changes in the molecular architecture of a series of terpolymers allow for the design of polymers with varying glass transition temperatures and degradation rates. The effect of each component in the terpolymers is quantified via design of experiment (DoE) analysis. A linear relationship between terpolymer components and resulting Tg (ranging from 34 to 86 °C) was demonstrated. These findings were further supported with mass-per-flexible-bond (MPFB) analysis. The effect of terpolymer composition on the in vitro degradation of these polymers revealed molecular weight loss ranging from 20 to 60% within the first 24 hours. DoE modeling further illustrated the linear (but reciprocal) relationship between structure elements and degradation for these polymers. Thus, we describe a simple technique to provide insight into the structure property relationship of degradable polymers, specifically applied using a new family of tyrosine-derived polycarbonates, allowing for optimal design of materials for specific applications. PMID:23888354

  2. Molecular design and evaluation of biodegradable polymers using a statistical approach.

    Science.gov (United States)

    Lewitus, Dan Y; Rios, Fabian; Rojas, Ramiro; Kohn, Joachim

    2013-11-01

    The challenging paradigm of bioresorbable polymers, whether in drug delivery or tissue engineering, states that a fine-tuning of the interplay between polymer properties (e.g., thermal, degradation), and the degree of cell/tissue replacement and remodeling is required. In this paper we describe how changes in the molecular architecture of a series of terpolymers allow for the design of polymers with varying glass transition temperatures and degradation rates. The effect of each component in the terpolymers is quantified via design of experiment (DoE) analysis. A linear relationship between terpolymer components and resulting Tg (ranging from 34 to 86 °C) was demonstrated. These findings were further supported with mass-per-flexible-bond analysis. The effect of terpolymer composition on the in vitro degradation of these polymers revealed molecular weight loss ranging from 20 to 60 % within the first 24 h. DoE modeling further illustrated the linear (but reciprocal) relationship between structure elements and degradation for these polymers. Thus, we describe a simple technique to provide insight into the structure property relationship of degradable polymers, specifically applied using a new family of tyrosine-derived polycarbonates, allowing for optimal design of materials for specific applications.

  3. Application of ATP-based bioluminescence for bioaerosol quantification: effect of sampling method.

    Science.gov (United States)

    Han, Taewon; Wren, Melody; DuBois, Kelsey; Therkorn, Jennifer; Mainelis, Gediminas

    2015-12-01

    An adenosine triphosphate (ATP)-based bioluminescence has potential to offer a quick and affordable method for quantifying bioaerosol samples. Here we report on our investigation into how different bioaerosol aerosolization parameters and sampling methods affect bioluminescence output per bacterium, and implications of that effect for bioaerosol research. Bacillus atrophaeus and Pseudomonas fluorescens bacteria were aerosolized by using a Collison nebulizer (BGI Inc., Waltham, MA) with a glass or polycarbonate jar and then collected for 15 and 60 min with: (1) Button Aerosol Sampler (SKC Inc., Eighty Four, PA) with polycarbonate, PTFE, and cellulose nitrate filters, (2) BioSampler (SKC Inc.) with 5 and 20 mL of collection liquid, and (3) our newly developed Electrostatic Precipitator with Superhydrophobic Surface (EPSS). For all aerosolization and sampling parameters we compared the ATP bioluminescence output per bacterium relative to that before aerosolization and sampling. In addition, we also determined the ATP reagent storage and preparation conditions that that do not affect the bioluminescence signal intensity. Our results show that aerosolization by a Collison nebulizer with a polycarbonate jar yields higher bioluminescence output per bacterium compared to the glass jar. Interestingly enough, the bioluminescence output by P. fluorescens increased substantially after its aerosolization compared to the fresh liquid suspension. For both test microorganisms, the bioluminescence intensity per bacterium after sampling was significantly lower than that before sampling suggesting negative effect of sampling stress on bioluminescence output. The decrease in bioluminescence intensity was more pronounces for longer sampling times and significantly and substantially depended on the sampling method. Among the investigated method, the EPSS was the least injurious for both microorganisms and sampling times. While the ATP-based bioluminescence offers a quick bioaerosol

  4. Dual-Component Gelatinous Peptide/Reactive Oligomer Formulations as Conduit Material and Luminal Filler for Peripheral Nerve Regeneration.

    Science.gov (United States)

    Kohn-Polster, Caroline; Bhatnagar, Divya; Woloszyn, Derek J; Richtmyer, Matthew; Starke, Annett; Springwald, Alexandra H; Franz, Sandra; Schulz-Siegmund, Michaela; Kaplan, Hilton M; Kohn, Joachim; Hacker, Michael C

    2017-05-21

    Toward the next generation of nerve guidance conduits (NGCs), novel biomaterials and functionalization concepts are required to address clinical demands in peripheral nerve regeneration (PNR). As a biological polymer with bioactive motifs, gelatinous peptides are promising building blocks. In combination with an anhydride-containing oligomer, a dual-component hydrogel system (cGEL) was established. First, hollow cGEL tubes were fabricated by a continuous dosing and templating process. Conduits were characterized concerning their mechanical strength, in vitro and in vivo degradation and biocompatibility. Second, cGEL was reformulated as injectable shear thinning filler for established NGCs, here tyrosine-derived polycarbonate-based braided conduits. Thereby, the formulation contained the small molecule LM11A-31. The biofunctionalized cGEL filler was assessed regarding building block integration, mechanical properties, in vitro cytotoxicity, and growth permissive effects on human adipose tissue-derived stem cells. A positive in vitro evaluation motivated further application of the filler material in a sciatic nerve defect. Compared to the empty conduit and pristine cGEL, the functionalization performed superior, though the autologous nerve graft remains the gold standard. In conclusion, LM11A-31 functionalized cGEL filler with extracellular matrix (ECM)-like characteristics and specific biochemical cues holds great potential to support PNR.

  5. Photoprotection by foliar anthocyanins mitigates effects of boron toxicity in sweet basil (Ocimum basilicum).

    Science.gov (United States)

    Landi, Marco; Guidi, Lucia; Pardossi, Alberto; Tattini, Massimiliano; Gould, Kevin S

    2014-11-01

    Boron (B) toxicity is an important agricultural problem in arid environments. Excess edaphic B compromises photosynthetic efficiency, limits growth and reduces crop yield. However, some purple-leafed cultivars of sweet basil (Ocimum basilicum) exhibit greater tolerance to high B concentrations than do green-leafed cultivars. We hypothesised that foliar anthocyanins protect basil leaf mesophyll from photo-oxidative stress when chloroplast function is compromised by B toxicity. Purple-leafed 'Red Rubin' and green-leafed 'Tigullio' cultivars, grown with high or negligible edaphic B, were given a photoinhibitory light treatment. Possible effects of photoabatement by anthocyanins were simulated by superimposing a purple polycarbonate filter on the green leaves. An ameliorative effect of light filtering on photosynthetic quantum yield and on photo-oxidative load was observed in B-stressed plants. In addition, when green protoplasts from both cultivars were treated with B and illuminated through a screen of anthocyanic protoplasts or a polycarbonate film which approximated cyanidin-3-O-glucoside optical properties, the degree of photoinhibition, hydrogen peroxide production, and malondialdehyde content were reduced. The data provide evidence that anthocyanins exert a photoprotective role in purple-leafed basil mesophyll cells, thereby contributing to improved tolerance to high B concentrations.

  6. Bisphenol A in dental sealants and its estrogen like effect.

    Science.gov (United States)

    Rathee, Manu; Malik, Poonam; Singh, Jyotirmay

    2012-05-01

    Bisphenol A or BPA-based epoxy resins are widely used in the manufacture of commercial products, including dental resins, polycarbonate plastics, and the inner coating of food cans. BPA is a precursor to the resin monomer Bis-GMA. During the manufacturing process of Bis-GMA dental sealants, Bisphenol A (BPA) might be present as an impurity or as a degradation product of Bis-DMA through esterases present in saliva. Leaching of these monomers from resins can occur during the initial setting period and in conjunction with fluid sorption and desorption over time and this chemical leach from dental sealants may be bioactive. Researchers found an estrogenic effect with BPA, Bis-DMA, and Bis-GMA because BPA lacks structural specificity as a natural ligand to the estrogen receptor. It generated considerable concern regarding the safety of dental resin materials. This review focuses on the BPA in dental sealants and its estrogen-like effect.

  7. Bisphenol A in dental sealants and its estrogen like effect

    Directory of Open Access Journals (Sweden)

    Manu Rathee

    2012-01-01

    Full Text Available Bisphenol A or BPA-based epoxy resins are widely used in the manufacture of commercial products, including dental resins, polycarbonate plastics, and the inner coating of food cans. BPA is a precursor to the resin monomer Bis-GMA. During the manufacturing process of Bis-GMA dental sealants, Bisphenol A (BPA might be present as an impurity or as a degradation product of Bis-DMA through esterases present in saliva. Leaching of these monomers from resins can occur during the initial setting period and in conjunction with fluid sorption and desorption over time and this chemical leach from dental sealants may be bioactive. Researchers found an estrogenic effect with BPA, Bis-DMA, and Bis-GMA because BPA lacks structural specificity as a natural ligand to the estrogen receptor. It generated considerable concern regarding the safety of dental resin materials. This review focuses on the BPA in dental sealants and its estrogen-like effect.

  8. Investigação da influência do processamento na dinâmica molecular de nanocompósitos de policarbonato e argila organofílica obtidos via intercalação por fusão On the influence of processing parameters on the molecular dynamics of melt intercalated polycarbonate-clay nanocomposites

    Directory of Open Access Journals (Sweden)

    Elton J. da R. Rodrigues

    2012-01-01

    Full Text Available Nanocompósitos baseados em policarbonato e argila organofílica foram obtidos pelo método de intercalação por fusão em câmara de mistura sob diferentes valores de torque e temperatura. A influência desses parâmetros na qualidade da dispersão da argila na matriz polimérica foi investigada por ressonância magnética nuclear (RMN de baixo campo, empregando o tempo de relaxação longitudinal, T1H, e por difração de raios X. As diferenças nos tempos de relaxação longitudinal e nos padrões de difração de raios X foram correlacionadas com a formação de domínios com mobilidades distintas. O nanomaterial formado apresentou morfologia intercalada com afastamento crescente das camadas de argila, conforme as condições de processamento se tornavam mais severas. A RMN ¹H mostrou que tanto o cisalhamento quanto a temperatura afetaram a mobilidade das cadeias poliméricas, explicitando a homogeneidade crescente da distribuição dos domínios de relaxação, de acordo com o aumento do torque e da temperatura.Polycarbonate-organofilic clay nanocomposites were obtained via the melt intercalation method in the blending chamber of a torque rheometer, under distinct values of shear and temperature. The influence of those processing parameters on the clay dispersion in the polymer matrix was probed by low-field nuclear magnetic resonance (NMR, using the T1H measurement technique and by wide angle X-ray scattering (WAXS. The differences in longitudinal relaxation times and in the X-ray reflection patterns were correlated with the formation of relaxation domains with particular molecular mobility, as progressively larger intercalated morphologies were found in the nanocomposites due to the increase of shear stress and temperature. ¹H NMR has shown that both shearing and temperature have played a fundamental part on the polymer chains mobility, which explains the increase in the domain´s homogeneity following the increment of those processing

  9. Dynamic Experiments and Constitutive Model Performance for Polycarbonate

    Science.gov (United States)

    2014-07-01

    Storage and loss tangent moduli for PC; DMA experiments performed at 1 Hz and shift at 100 Hz showing the  and transition regions using the...author would also like to thank Dr. Adam D. Mulliken for courteously providing the experimental results and the Abaqus version of the model and...exponential factor . In 1955, the Ree-Eyring model further accounted for microstructural mechanisms by relating molecular motions to yield behavior

  10. Nuclear track detection using thermoset polycarbonates derived from pentaerythritol

    Energy Technology Data Exchange (ETDEWEB)

    Mandrekar, Vinod K. [Department of Chemistry, Goa University, Goa-403 206 (India); Chourasiya, G. [M P and T Section, Radiological Physics and Advisory Division, Bhabha Atomic Research Center, Mumbai-400 085 (India); Kalsi, P.C. [Radiochemistry Division, Bhabha Atomic Research Center, Mumbai-400 085 (India); Tilve, S.G. [Department of Chemistry, Goa University, Goa-403 206 (India); Nadkarni, V.S., E-mail: nitin@unigoa.ac.i [Department of Chemistry, Goa University, Goa-403 206 (India)

    2010-03-01

    The paper describes the synthesis and performance of two polymers as nuclear track detectors, both having alpha sensitivity higher than that of the widely-used polymer CR-39. A homopolymer (PPETAC) from pentaerythritol tetrakis(allyl carbonate) (PETAC) monomer and its various copolymers with allyl diglycol carbonate (ADC) prepared by cast polymerization were successfully used as nuclear track detectors. The copolymer PETAC:ADC 4:6 weight percent shows maximum alpha sensitivity, almost double that of CR-39 under identical experimental conditions. This copolymer can reveal alpha particle tracks from {sup 239}Pu source in about 60 min and {sup 252}Cf fission fragment tracks by chemical etching in less than 30 min, compared to about 120 min and 45 min respectively, required by CR-39. The polymers can be conveniently etched using aqueous sodium hydroxide.

  11. Nuclear track detection using thermoset polycarbonates derived from pentaerythritol

    International Nuclear Information System (INIS)

    Mandrekar, Vinod K.; Chourasiya, G.; Kalsi, P.C.; Tilve, S.G.; Nadkarni, V.S.

    2010-01-01

    The paper describes the synthesis and performance of two polymers as nuclear track detectors, both having alpha sensitivity higher than that of the widely-used polymer CR-39. A homopolymer (PPETAC) from pentaerythritol tetrakis(allyl carbonate) (PETAC) monomer and its various copolymers with allyl diglycol carbonate (ADC) prepared by cast polymerization were successfully used as nuclear track detectors. The copolymer PETAC:ADC 4:6 weight percent shows maximum alpha sensitivity, almost double that of CR-39 under identical experimental conditions. This copolymer can reveal alpha particle tracks from 239 Pu source in about 60 min and 252 Cf fission fragment tracks by chemical etching in less than 30 min, compared to about 120 min and 45 min respectively, required by CR-39. The polymers can be conveniently etched using aqueous sodium hydroxide.

  12. Tolerance Verification of Micro and Nano Structures on Polycarbonate Substrates

    DEFF Research Database (Denmark)

    Gasparin, Stefania; Tosello, Guido; Hansen, Hans Nørgaard

    2010-01-01

    Micro and nano structures are an increasing challenge in terms of tolerance verification and process quality control: smaller dimensions led to a smaller tolerance zone to be evaluated. This paper focuses on the verification of CD, DVD and HD-DVD nanoscale features. CD tolerance features are defi......Micro and nano structures are an increasing challenge in terms of tolerance verification and process quality control: smaller dimensions led to a smaller tolerance zone to be evaluated. This paper focuses on the verification of CD, DVD and HD-DVD nanoscale features. CD tolerance features...

  13. Dielectric properties of polycarbonate coated natural fabric Grewia tilifolia

    CSIR Research Space (South Africa)

    Ramana, CHVV

    2011-12-01

    Full Text Available Natural fibers are emerging as low cost, lightweight and apparently environmentally superior alternatives to glass fibers in composites. With the increasing importance of environmental interactions, several innovations of the environmental...

  14. Implementation of neural network for color properties of polycarbonates

    Science.gov (United States)

    Saeed, U.; Ahmad, S.; Alsadi, J.; Ross, D.; Rizvi, G.

    2014-05-01

    In present paper, the applicability of artificial neural networks (ANN) is investigated for color properties of plastics. The neural networks toolbox of Matlab 6.5 is used to develop and test the ANN model on a personal computer. An optimal design is completed for 10, 12, 14,16,18 & 20 hidden neurons on single hidden layer with five different algorithms: batch gradient descent (GD), batch variable learning rate (GDX), resilient back-propagation (RP), scaled conjugate gradient (SCG), levenberg-marquardt (LM) in the feed forward back-propagation neural network model. The training data for ANN is obtained from experimental measurements. There were twenty two inputs including resins, additives & pigments while three tristimulus color values L*, a* and b* were used as output layer. Statistical analysis in terms of Root-Mean-Squared (RMS), absolute fraction of variance (R squared), as well as mean square error is used to investigate the performance of ANN. LM algorithm with fourteen neurons on hidden layer in Feed Forward Back-Propagation of ANN model has shown best result in the present study. The degree of accuracy of the ANN model in reduction of errors is proven acceptable in all statistical analysis and shown in results. However, it was concluded that ANN provides a feasible method in error reduction in specific color tristimulus values.

  15. NMR and vibrational spectroscopic study of the order and mobility in polycarbonate and polycarbonate - poly(ethylene oxide) blends

    Czech Academy of Sciences Publication Activity Database

    Dybal, Jiří; Brus, Jiří; Schmidt, Pavel

    1999-01-01

    Roč. 146, - (1999), s. 17-23 ISSN 1022-1360. [International Symposium on Molecular Order and Mobility in Polymer Systems /3./. St. Petersburg, 07.06.1999-10.06.1999] R&D Projects: GA ČR GA203/97/0539 Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.539, year: 1999

  16. Estrogen receptor-dependent effects of bisphenol a

    Directory of Open Access Journals (Sweden)

    P. Bulzomi

    2011-01-01

    Full Text Available Bisphenol A (BPA, commonly used as building block of polycarbonate plastics, significantly affects human and animal health interfering with the action of natural hormones. Within BPA disrupting effects, a mitogenic activity and, consequently, an increased incidence of neoplastic transformations has been reported in exposed organisms. Among the several mechanisms proposed for the mitogenic BPA effects, its ability to bind to estrogen receptors (ERα and ERβ deserves particular attention. Aim of this work is to investigate ERα- and ERβ-dependent mechanisms underlying BPA proliferative effect. Binding assay confirms that BPA binds to both ERs. Cell vitality assay and Western blot analysis of protein involved in cell proliferation demonstrate that BPA acts as a double side disruptor of estrogenic effects. In fact in the presence of ERα, BPA mimics E2, increasing cell proliferation. On the contrary, in the presence of ERβ, BPA acts as an E2 antagonist preventing the hormone-induced cancer cells apoptosis. These two divergent aspects could act synergistically in the exposed organisms leading to the disruption of the balance between proliferation and apoptosis typical of E2 effects.

  17. Bisphenol A in Reproduction: Epigenetic Effects.

    Science.gov (United States)

    Chianese, Rosanna; Troisi, Jacopo; Richards, Sean; Scafuro, Marika; Fasano, Silvia; Guida, Maurizio; Pierantoni, Riccardo; Meccariello, Rosaria

    2018-02-21

    Bisphenol A (BPA) is an endocrine disrupting chemical widely used in the manufacture of polycarbonate plastic and epoxy resin to produce a multitude of consumer products, food and drink containers, and medical devices. BPA is similar to estradiol in structure and thus interferes in steroid signalling with different outcomes on reproductive health depending on doses, life stage, mode, and timing of exposure. In this respect, it has an emerging and controversial role as a "reproductive toxicant" capable of inducing short and long-term effects including the modulation of gene expression through epigenetic modification (i.e. methylation of CpG islands, histone modifications and production of non-coding RNA) with direct and trans-generational effects on exposed organisms and their offspring, respectively. This review provides an overview about BPA effects on reproductive health and aims to summarize the epigenetic effects of BPA in male and female reproduction. BPA exerts epigenetic effects in both male and female reproduction. In males, BPA affects spermatogenesis and sperm quality and possible trans-generational effects on the reproductive ability of the offspring. In females, BPA affects ovary, embryo development, and gamete quality for successful in vivo and in vitro fertilization (IVF). The exact mechanisms of BPA-mediated effects in reproduction are not fully understood; however, the environmental exposure to BPA - especially in fetal and neonatal period - deserves attention to preserve the reproductive ability in both sexes and to reduce the epigenetic risk for the offspring. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  18. Effects of Radiation on Capacitor Dielectrics

    Science.gov (United States)

    Bouquet, F. L.; Somoano, R. B.; Frickland, P. O.

    1987-01-01

    Data gathered on key design parameters. Report discusses study of electrical and mechanical properties of irradiated polymer dielectric materials. Data compiled for use by designers of high-energy-density capacitors that operate in presence of ionizing radiation. Study focused on polycarbonates, polyetheretherketones, polymethylpentenes, polyimides (including polyetherimide), polyolefins, polysulfones (including polyethersulfone and polyphenylsulfone), and polyvinylidene fluorides.

  19. Effectiveness of Sunscreen at Preventing Solar UV-Induced Alterations of Human Stratum Corneum

    Science.gov (United States)

    Martinez, O.; Dauskardt, R.; Biniek, K.; Novoa, F.

    2012-12-01

    The outermost layer of the epidermis, the stratum corneum, protects the body from harmful environmental conditions by serving as a selective barrier. Solar ultraviolet (UV) radiation is one of the most common conditions the body encounters and is responsible for many negative skin responses, including compromised barrier function. UV exposure has dramatic effects on stratum corneum cell cohesion and mechanical integrity that are related to its effects on the stratum corneum's intercellular lipids. Hypothesis Sunscreen contains chemicals that absorb UV radiation to prevent the radiation from penetrating the skin. Thus, it is expected that the application of sunscreen on human stratum corneum will reduce UV-induced alterations of human stratum corneum. Procedures/Equipment Human tissue was processed in order to isolate the stratum corneum, the top layer of the epidermis. Double cantilever beam (DCB) testing was used to study the effect of UV radiation on human stratum corneum. Two different types of DCB samples were created: control DCB samples with the application of carrier and UV light to the stratum corneum and DCB samples with the application of sunscreen and UV light to the stratum corneum. For the control sample, one side of the stratum corneum was glued to a polycarbonate beam and carrier was applied. Then, the sample was placed 10 cm away from the UV lamp inside of the environmental chamber and were exposed to UV dosages of about 800 J/cm2. Once this step was complete, a second polycarbonate beam was glued to the other side of the stratum corneum. The steps were similar for the DCB sample that had sunscreen applied and that was exposed to UV light. After gluing one side of the stratum corneum to a polycarbonate beam, Octinoxate sunscreen was applied. The next steps were similar to those of the control sample. All DCB samples were then let out to dry for two hours in a dry box in order for the moisture from the lab to be extracted. Each DCB sample was tested

  20. Theoretical evaluation of the effects of molecular contaminants on grazing incidence mirrors

    Science.gov (United States)

    Sanders, Jack T., Jr.

    2000-09-01

    Molecular contaminants degrade the optical or thermal properties of spacecraft systems. In the case of grazing incidence mirrors, they may even increase the system throughput at certain wavelengths. Theoretical calculations using a semi-imprircal model developed by Henke, Davis and Gullickson at the Lawrence Berkeley National Laboratory show the effect of varying film thickness' on mirror reflectivity.2 The reflectivity is a product of the base material and any thin films, including molecular contaminants. The effect on nickel, gold, and Zerodur substrates are evaluated with polycarbonate, polypropylene and poly(dimenthyl silicone) contaminants in the range of 5 to 100 Angstroms x-ray wavelength. X-rays pass through the film until they meet an atom; they are then scattered elastically or absorbed. Photoabsorption occurs when the photon energy is equal to or greater than the energy required to promote an inner shell electron out of the atom. Strategies for evaluating contaminant effects with different light sources are included, taking into account the scattering cross section, expressed as mirror reflectance, of the materials involved.

  1. Bisphenol-A: Epigenetic Reprogramming and Effects on Reproduction and Behavior

    Directory of Open Access Journals (Sweden)

    Guergana Mileva

    2014-07-01

    Full Text Available Bisphenol A (BPA is a synthetic compound used in the production of many polycarbonate plastics and epoxy resins. It is one of the most widely produced chemicals in the world today and is found in most canned goods, plastics, and even household dust. Exposure to BPA is almost universal: most people have measurable amounts of BPA in both urine and serum. BPA is similar in structure to estradiol and can bind to multiple targets both inside and outside the nucleus, in effect acting as an endocrine disruptor. Research on BPA exposure has accelerated in the past decade with findings suggesting that perinatal exposure to BPA can negatively impact both male and female reproduction, create alterations in behavior, and act as a carcinogen. BPA can have both short term and long term effects with the latter typically occurring through epigenetic mechanisms such as DNA methylation. This review will draw on both human and animal studies in an attempt to synthesize the literature and examine the effects of BPA exposure on reproduction, behavior, and carcinogenesis with a focus on the potential epigenetic mechanisms by which it acts.

  2. Effect of bisphenol A on P-glycoprotein-mediated efflux and ultrastructure of the sea urchin embryo

    Energy Technology Data Exchange (ETDEWEB)

    Bošnjak, Ivana [Laboratory for Biology and Microbial Genetics, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, Pierottijeva 6, Zagreb (Croatia); Borra, Marco [Molecular Biology Service, Stazione Zoologica Anton Dohrn, Villa Comunale 80121, Napoli (Italy); Iamunno, Franco; Benvenuto, Giovanna [Electron Microscopy Service, Stazione Zoologica Anton Dohrn, Villa Comunale 80121, Napoli (Italy); Ujević, Ivana [Laboratory of Plankton and Shellfish Toxicity, Institute of Oceanography and Fisheries, Setaliste Ivana Mestrovica 63, 21000 Split (Croatia); Bušelić, Ivana [Laboratory for Aquaculture, Institute of Oceanography and Fisheries, Setaliste Ivana Mestrovica 63, 21000 Split (Croatia); Roje-Busatto, Romana [Laboratory of Plankton and Shellfish Toxicity, Institute of Oceanography and Fisheries, Setaliste Ivana Mestrovica 63, 21000 Split (Croatia); Mladineo, Ivona, E-mail: mladineo@izor.hr [Laboratory for Aquaculture, Institute of Oceanography and Fisheries, Setaliste Ivana Mestrovica 63, 21000 Split (Croatia); Assemble Marine Laboratory, Stazione Zoological Anton Dohrn, Villa Comunale, Naples (Italy)

    2014-11-15

    Highlights: • Effects of BPA on embryonic development of Paracentrotus lividus were determined. • Transport assay, intracellular BPA measurements and gene expression surveys were made. • Multidrug efflux transporter P-gp/ABCB1 is involved in BPA elimination. • Endocrine disruption is inferred by orphan steroid hormone receptor (shr2) upregulation. • BPA delayed mitosis, inducing aberrant karyokinesis and dysfunctional microfilaments. - Abstract: Usage of bisphenol A (BPA) in production of polycarbonate plastics has resulted in global distribution of BPA in the environment. These high concentrations cause numerous negative effects to the aquatic biota, among which the most known is the induction of endocrine disruption. The focus of this research was to determine the effects of two experimentally determined concentrations of BPA (100 nM and 4 μM) on cellular detoxification mechanisms during the embryonic development (2-cell, pluteus) of the rocky sea urchin (Paracentrotus lividus), primarily the potential involvement of multidrug efflux transport in the BPA intercellular efflux. The results of transport assay, measurements of the intracellular BPA and gene expression surveys, for the first time indicate the importance of P-glycoprotein (P-gp/ABCB1) in defense against BPA. Cytotoxic effects of BPA, validated by the immunohistochemistry (IHC) and the transmission electron microscopy (TEM), induced the aberrant karyokinesis, and consequently, the impairment of embryo development through the first cell division and retardation.

  3. The effect of cycling deflection on the injection-molded thermoplastic denture base resins.

    Science.gov (United States)

    Hamanaka, Ippei; Iwamoto, Misa; Lassila, Lippo Vj; Vallittu, Pekka K; Shimizu, Hiroshi; Takahashi, Yutaka

    2016-01-01

    The aim of this study was to evaluate the effect of cycling deflection on the flexural behavior of injection-molded thermoplastic resins. Six injection-molded thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethyl methacrylate) and, as a control, a conventional heat-polymerized denture based polymer of polymethyl methacrylate (PMMA) were used in this study. The cyclic constant magnitude (1.0 mm) of 5000 cycles was applied using a universal testing machine to demonstrate plasticization of the polymer. Loading was carried out in water at 23ºC with eight specimens per group (n = 8). Cycling load (N) and deformation (mm) were measured. Force required to deflect the specimens during the first loading cycle and final loading cycle was statistically significantly different (p 0.05). None of the materials fractured during the loading test. One polyamide based polymer (Valplast) displayed the highest deformation and PMMA based polymers (Acrytone and Acron) exhibited the second highest deformation among the denture base materials. It can be concluded that there were considerable differences in the flexural behavior of denture base polymers. This may contribute to the fatigue resistance of the materials.

  4. High dose gamma ray exposure effect on the properties of CdSe nanowires

    Science.gov (United States)

    Narula, Chetna; Chauhan, R. P.

    2018-03-01

    We report high dose gamma-ray (γ-ray) induced modifications incurred by polycrystalline cadmium selenide (CdSe) nanowires of 80 nm diameter. The nanowires have been synthesized using polycarbonate template assisted electro-deposition technique. The samples were irradiated with 60Co γ-radiation at a dose rate of 4.533 kGy/h for different time intervals with doses varying from 0 to 400 kGy. The effects of γ rays on the structural, morphological, optical and electrical properties of nanowires are discussed. XRD patterns of as-synthesized and gamma irradiated CdSe nanowires did not show any phase transformations but the variation in relative intensity was observed. The crystallite size evaluated using Scherrer's formula was found to vary. The optical parameters were obtained using UV-vis spectrometer measurements of absorption. Band gap was found to decrease with γ irradiation up to a dose of 300 kGy after which it was seen to increase. Refractive index and optical dielectric constants were also evaluated. Subjection of γ-radiation also brings about key changes in the electrical properties of CdSe nanowires. The attained data shows that the electrical conductivity varies with absorbed dose. The variations in the properties of CdSe nanowires can be considered as a consequence of ionization process, defect production and its annihilation.

  5. Molecular analysis of the apoptotic effects of BPA in acute myeloid leukemia cells

    Directory of Open Access Journals (Sweden)

    Del Pozzo Giovanna

    2009-06-01

    Full Text Available Abstract Background: BPA (bisphenol A or 2,2-bis(4-hydroxy-phenolpropane is present in the manufacture of polycarbonate plastic and epoxy resins, which can be used in impact-resistant safety equipment and baby bottles, as protective coatings inside metal food containers, and as composites and sealants in dentistry. Recently, attention has focused on the estrogen-like and carcinogenic adverse effects of BPA. Thus, it is necessary to investigate the cytotoxicity and apoptosis-inducing activity of this compound. Methods: Cell cycle, apoptosis and differentiation analyses; western blots. Results: BPA is able to induce cell cycle arrest and apoptosis in three different acute myeloid leukemias. Although some granulocytic differentiation concomitantly occurred in NB4 cells upon BPA treatment, the major action was the induction of apoptosis. BPA mediated apoptosis was caspase dependent and occurred by activation of extrinsic and intrinsic cell death pathways modulating both FAS and TRAIL and by inducing BAD phosphorylation in NB4 cells. Finally, also non genomic actions such as the early decrease of both ERK and AKT phosphorylation were induced by BPA thus indicating that a complex intersection of regulations occur for the apoptotic action of BPA. Conclusion: BPA is able to induce apoptosis in leukemia cells via caspase activation and involvement of both intrinsic and extrinsic pathways of apoptosis.

  6. Effect of water temperature on the fit of provisional crown margins during polymerization.

    Science.gov (United States)

    Ogawa, T; Aizawa, S; Tanaka, M; Matsuya, S; Hasegawa, A; Koyano, K

    1999-12-01

    When fabricating a provisional crown with the direct technique, dentists are concerned with margin discrepancies that result from polymerization shrinkage. This in vitro study examined the effect of water temperature on the fit of provisional crown margins during resin polymerization. The experiment was designed to simulate a direct technique to fabricate provisional crowns. After mixing autopolymerizing methyl methacrylate resin, the material was placed in a preformed polycarbonate crown. The crown was seated on a prepared premolar-shaped die with a shoulder margin. After 1 minute and 50 seconds, the crown was removed and polymerization was continued under the following conditions: 20 degrees C air, and water at 0 degrees C, 10 degrees C, 20 degrees C, 30 degrees C, 40 degrees C, 60 degrees C, and 80 degrees C. Six minutes after polymerization, the crown was trimmed and reseated on the die. Discrepancy of crown margin was measured with a 3-dimensional digitizer. Margin discrepancy varied with the condition during resin-polymerization (ANOVA, P crowns polymerized in 20 degrees C and 30 degrees C water revealed the best margin fit, showing 3 times more accurate margin fit than those polymerized in 20 degrees C air (Bonferroni/Dunn procedure, P provisional crowns using the direct technique. Water temperatures of 20 degrees C and 30 degrees C produced the best fit at the margin of the provisional crown.

  7. The effects of physico-chemical interactions and polymer grafting on interfacial adhesion in thermoplastic composites

    Science.gov (United States)

    Raghavendra, Venkat Krishna

    The effects of physico-chemical interactions between the carbon fiber and Bisphenol-A polycarbonate matrix was investigated to understand the factors governing the interfacial adhesion in thermoplastic matrix composites. It was found that, the changes in the amount of oxygen functionality achieved through electrochemical oxidative surface treatment of the carbon fibers didn't affect the level of adhesion, indicating negligible polar and hydrogen bond formation. Composites fabricated from these fibers that were subsequently passivated through thermal hydrogenation up to 1000°C, which removed all the oxygen functionality without affecting the fiber topography, indicated that the mechanical interlocking between the fiber and the matrix didn't have a strong influence on the interfacial adhesion. Grafting low molecular weight BPA-PC and high molecular weight PMMA on to the fiber surface improved the interfacial adhesion. However, the level of improvement was observed to be independent of the fiber surface treatment and the molecular weight of the grafted chains. These results are consistent with the cohesive zone models proposed for the chain pull out and chain scission observed in block copolymers.

  8. The effects of water sample treatment, preparation, and storage prior to cyanotoxin analysis for cylindrospermopsin, microcystin and saxitoxin.

    Science.gov (United States)

    Kamp, Lisa; Church, Jennifer L; Carpino, Justin; Faltin-Mara, Erin; Rubio, Fernando

    2016-02-25

    Cyanobacterial harmful algal blooms occur in freshwater lakes, ponds, rivers, and reservoirs, and in brackish waters throughout the world. The wide variety of cyanotoxins and their congeners can lead to frequent exposure of humans through consumption of meat, fish, seafood, blue-green algal products and water, accidental ingestion of contaminated water and cyanobacterial scum during recreational activities, and inhalation of cyanobacterial aerosols. Cyanotoxins can also occur in the drinking water supply. In order to monitor human exposure, sensitive analytical methods such as enzyme linked immunosorbent assay and liquid chromatography-mass spectrometry are often used. Regardless of the analytical method of choice, some problems regularly occur during sample collection, treatment, storage, and preparation which cause toxin loss and therefore underestimation of the true concentration. To evaluate the potential influence of sample treatment, storage and preparation materials on surface and drinking water samples, the effects of different types of materials on toxin recovery were compared. Collection and storage materials included glass and various types of plastics. It was found that microcystin congeners LA and LF adsorbed to polystyrene, polypropylene, high density polyethylene and polycarbonate storage containers, leading to low recoveries (LR to water samples immediately upon sample collection is critical for accurate analysis. In addition, the effect of various drinking water treatment chemicals on toxin recovery and the behavior of those chemicals in the enzyme linked immunosorbent assays were also studied and are summarized. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  9. A review on bisphenol A occurrences, health effects and treatment process via membrane technology for drinking water.

    Science.gov (United States)

    Muhamad, Mimi Suliza; Salim, Mohd Razman; Lau, Woei Jye; Yusop, Zulkifli

    2016-06-01

    Massive utilization of bisphenol A (BPA) in the industrial production of polycarbonate plastics has led to the occurrence of this compound (at μg/L to ng/L level) in the water treatment plant. Nowadays, the presence of BPA in drinking water sources is a major concern among society because BPA is one of the endocrine disruption compounds (EDCs) that can cause hazard to human health even at extremely low concentration level. Parallel to these issues, membrane technology has emerged as the most feasible treatment process to eliminate this recalcitrant contaminant via physical separation mechanism. This paper reviews the occurrences and effects of BPA toward living organisms as well as the application of membrane technology for their removal in water treatment plant. The potential applications of using polymeric membranes for BPA removal are also discussed. Literature revealed that modifying membrane surface using blending approach is the simple yet effective method to improve membrane properties with respect to BPA removal without compromising water permeability. The regeneration process helps in maintaining the performances of membrane at desired level. The application of large-scale membrane process in treatment plant shows the feasibility of the technology for removing BPA and possible future prospect in water treatment process.

  10. Effect of Bisphenol-A (BPA) on insulin signal transduction and GLUT4 translocation in gastrocnemius muscle of adult male albino rat.

    Science.gov (United States)

    Mullainadhan, Vigneswari; Viswanathan, Mangala Priya; Karundevi, Balasubramanian

    2017-09-01

    Environmental estrogens bind to estrogen receptors, mimic estrogenic actions, and have adverse effects on human health like Bisphenol - A (BPA) which is used as a monomer in the production of polycarbonate plastics (PC) and epoxy resins which are used in variety of canned foods. Skeletal muscle plays an essential role in maintaining systemic glucose metabolism. In the present study, we investigated the possible effects of BPA on insulin signalling molecules and GLUT4 translocation in the gastrocnemius muscle of adult male rat. Rats were divided into four groups - Group I: Control (vehicle-corn oil treated), Group II, III and IV were administered with BPA (10, 100 and 400mg/kg b.wt/day, respectively) through oral gavage. Fasting blood glucose level of BPA treated groups showed a significant increase, oral glucose tolerance and insulin tolerance were also impaired in these animals. BPA significantly decreased the protein levels of insulin signalling molecules like IR, IRS-1, Akt, AS160 and its phosphorylated forms and blunts GLUT4 translocation by altering the levels of v- and t- SNARE proteins that assist the translocation process, thereby decreasing glucose uptake and oxidation in the gastrocnemius muscle. These results suggest that BPA has detrimental effects on insulin signalling molecules and GLUT4 translocation in the gastrocnemius muscle and thus impairs glucose homeostasis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. The Effect of Bisphenol A on Liver Tissue Structure and Liver Enzymes

    Directory of Open Access Journals (Sweden)

    Ozra Rahimi

    2016-03-01

    Full Text Available Background and Objectives: Bisphenol A (BPA is one of the chemical materials, which is used as monomer of epoxy resins and polycarbonate plastics. The present study was performed with the purpose of determining the effect of A on liver enzymes level and liver tissue structure. Methods: In this experimental study 40 male rats were divided into 4 groups of 10 each: The control group received olive oil at a dose of 1μg/kg bw; group II received BPA at 10μg/kg bw; group III received BPA at 50μg/kg bw; and group IV received BPA at 100μg/kg bw. The groups were administered BPA intraperitoneally for 15 days. At the end, the rats were anesthetized and after extraction of serum, their liver were removed for examination of liver enzymes and evaluated by light microscopy after H&E staining. Results: The doses of 10 and 50μg/kg bw of BPA had no significant effect on ALT enzyme and 10μg/kg bw had no significant effect on AST enzyme (p>0.05, while BPA at dose of 100 and doses 50 and 100μg/kg bw had significant effects on ALT and AST, respectively, and increased their serum concentration. BPA only at dose of 100μg/kg bw caused inflammation and vacuolization in liver tissue, and its low concentrations had no significant effect on the liver tissue. Conclusion: The results indicated that low concentrations of BPA had no significant effect on liver tissue and enzymes, but its increased concentration can cause damage to liver tissue and increase the serum levels of liver enzymes.

  12. Behavioral effects in mice of postnatal exposure to low-doses of 137-cesium and bisphenol A

    International Nuclear Information System (INIS)

    Heredia, Luis; Bellés, Montserrat; LLovet, Maria Isabel; Domingo, Jose L.; Linares, Victoria

    2016-01-01

    Bisphenol A (BPA) is the most important plasticizer used in many household products such as polycarbonate plastics or epoxy resins. Public and scientific concerns exist regarding the possibility that the neonatal exposure to BPA may contribute to neurobehavioral disorders. On the other hand, there is little information on the effects of low doses of ionizing radiation during critical phases of postnatal brain development, as well as the combination of radiation and environmental chemicals. In this study, C57BL/6J mice were exposed to low doses of internal radiation ( 137 Cs), and/or BPA on postnatal day 10 (PND10). At the age of two months, animals were submitted to several tests to assess anxiety, activity, learning, and memory. Results showed that exposure to 137 Cs, alone or in combination with BPA, increased the anxiety-like of the animals without changing the activity levels. Animals exposed to 137 Cs showed impaired learning, and spatial memory, an impairment that was not observed in the groups co-exposed to BPA.

  13. Genotoxic effect of polycyclic aromatic hydrocarbons in the metropolitan area of Porto Alegre, Brazil, evaluated by Helix aspersa (Mueller, 1774)

    Energy Technology Data Exchange (ETDEWEB)

    Ianistcki, M. [Laboratorio de Genetica Toxicologica, Department of Biology, ULBRA, Av. Farroupilha 8001, Pr. 14/Sala 218, Bairro Sao Jose, CEP 92425-900 Canoas, RS (Brazil); Dallarosa, J. [Laboratorio de Ecologia, UFRGS (Brazil); Sauer, C.; Teixeira, C.E. [Fundacao Estadual de Protecao Ambiental Henrique Luis Roessler, FEPAM, RS (Brazil); Silva, J. da, E-mail: juliana.silva@ulbra.b [Laboratorio de Genetica Toxicologica, Department of Biology, ULBRA, Av. Farroupilha 8001, Pr. 14/Sala 218, Bairro Sao Jose, CEP 92425-900 Canoas, RS (Brazil)

    2009-07-15

    The purpose of this study was to biomonitor metropolitan areas of Porto Alegre (Brazil) for PAHs associated with atmospheric particles and check their effects on the DNA of the land mollusk Helix aspersa. The sampling sites are located in an urban area with heavy traffic: (i) Canoas, (ii) Sapucaia do Sul, and (iii) FIERGS/Porto Alegre. The samples were collected during a continuous period of 24 hours during 15 days using Stacked Filter Units (SFU) on polycarbonate filters (two separated size fractions: PM{sub 10-2.5} and PM{sub <2.5}). The concentrations of 16 major PAHs were determined according to EPA. Comet assay on H. aspersa hemolymph cells was chosen for genotoxicity evaluation. This evaluation shows that, in general, the smaller PM-size fractions (PM{sub <2.5}) have the highest genotoxicity and contain higher concentrations of extractable organic matter. In addition, associations between chemical characteristics and PM carcinogenicity tend to be stronger for the smaller PM-size fractions. - DNA damage in H. aspersa exposed to atmospheric particulate in Metropolitan Area of Porto Alegre demonstrated association with PAHs in the fine filter (PM{sub <2.5}).

  14. Physical Aging of Thin and Ultrathin Free-Standing Polymer Films: Effect of Stress and Reduced Glass Transitions

    Science.gov (United States)

    Pye, Justin; Roth, Connie

    2014-03-01

    While great effort has been made in elucidating the effect of confinement on the glass transition (Tg) in polymers, considerably less work has been done on physical aging. Starting with supported films, we have previously shown that the reduced physical aging rates in ultrathin polystyrene (PS) films can be linked to the reduced Tg near the free surface [Macromolecules 2010, 43, 8296]. We then showed that high molecular weight (MW) free-standing PS films have two reduced Tgs suggesting that two separate mechanisms are acting simultaneously to propagate enhanced mobility at the free surface deeper into the film [PRL 2011, 107, 235701]. To help determine the mechanisms of these two reduced Tgs, we performed physical aging measurements on these high MW free-standing PS films. For thick films (220-1800 nm) in which there are no Tg reductions, we find that the physical aging rate depends strongly on stress caused by thermal expansion mismatch between film and support. This stress, applied to the films as they are quenched into the glassy state, can nearly double the physical aging rate when changing the frame material from polycarbonate to silicon [Macromolecules 2013, DOI:10.1021/ma401872u]. Finally, ultrathin high MW PS films held at a temperature between the two Tgs do exhibit physical aging, indicating that at least some of the film is glassy between these two transitions.

  15. Impregnação de filmes do compósito de policarbonato (PC e sílicagel (Si com corante fotocrômico em fluido supercrítico = Impregnation of composite from polycarbonate (PC and silica gel (Si films with photochromic dye in supercritical fluid

    Directory of Open Access Journals (Sweden)

    Fernanda de Almeida Fin de Lima

    2010-01-01

    Full Text Available O objetivo deste trabalho foi estudar a impregnação do corante fotocromático Reversacol Graphit® em filmes do compósito de policarbonato (PC e sílica-gel (Si, com a finalidade de obter aplicações em lentes fotocrômicas. Filmes de PC puros também foramimpregnados nas mesmas condições, para verificar o efeito da adição de sílica-gel. Os filmes do compósito foram produzidos em proporções de Si:PC de 1:40 e 1:80 (m m-1, pelo método casting. Para a impregnação do corante Reversacol Graphit nos filmes obtidos foiutilizado o processo supercrítico, pela sua eficiência e benefícios. A impregnação foi feita nos tempos de 15, 30, 45, 60, 90, 120, 150 e 180 min. A temperatura e a pressão adotadas foram de 60ºC e 120 bar. A quantidade de pigmento impregnado nos filmes de Si:PC – 1:40e 1:80 (m m-1 foi de 29 e 23% de massa de corante por massa de compósito, respectivamente, e para o filme de PC puro foi de apenas 2,2% massa de corante por massa de compósito. Pelas análises térmicas, verificou-se que os filmes do compósito apresentarammaior estabilidade térmica. Pela técnica de microscopia eletrônica, observou-se que os filmes de PC puro e dos compósitos Si:PC – 1:40 e 1:80 (m m-1 apresentaram uma superfície lisa e homogênea.The aim of this work was to study the impregnation of the photochromic dye Reversacol Graphit® in composite films ofpolycarbonate (PC and silica gel, with the purpose of finding applications in photochromic lenses. Pure PC films were also impregnated in the same conditions, to verify the effect of the silica-gel addition. The composites films were produced in Si:PC ratios of 1:40 and 1:80 (m m-1, using the casting method . For the impregnation of the dye Reversacol Graphit in the obtained films, the supercritical process was used due to its efficiency and benefits. The impregnation was made in the times of 15, 30, 45, 60, 90, 120, 150 and 180 minutes. The adopted temperature and pressure

  16. Surface Modification of PDMS and Plastics with Zwitterionic Polymers.

    Science.gov (United States)

    Tanaka, Mutsuo; Kurosawa, Shigeru

    2017-07-01

    Surface modification of PDMS, polycarbonate, and acrylic resin was examined using various methacryl polymers bearing sulfobetaine, phosphoryl choline, and oligoethylene glycol units. We have found that zwitterionic polymers are adsorbed on the PDMS surface treated with plasma. The surface of PDMS is stable to keep high hydrophilicity after a month of the modification. On the other hand, one of sulfobetaine polymers showed distinguished adsorption behavior in the case of polycarbonate surface treated with plasma. Suppression effect for nonspecific adsorption of BSA was evaluated using polycarbonate and acrylic resin modified with the polymers. The modified surfaces showed suppression effect for nonspecific adsorption of BSA compared with the surface only treated with plasma.

  17. Dose-dependent effectiveness of wheel running to attenuate cocaine-seeking: impact of sex and estrous cycle in rats.

    Science.gov (United States)

    Peterson, Alexis B; Hivick, Daniel P; Lynch, Wendy J

    2014-07-01

    Exercise has shown promise as an intervention for drug addiction; however, little is known regarding the exercise conditions that most effectively reduce relapse vulnerability and whether these conditions differ by sex. Here, we examined sex differences in the dose-dependent effects of wheel running, an animal model of exercise, during abstinence on subsequent cocaine-seeking. Male and female rats self-administered cocaine (1.5 mg/kg/infusion) under extended access conditions (24 h/day, 4 discrete trials/h) for 10 days. Rats were then given voluntary access to either an unlocked or locked running wheel for 1, 2, 6, or 24 h/day during the 14-day abstinence period. Separate groups of rats were housed in polycarbonate cages during abstinence to control for physical activity that the wheel may provide. Subsequent cocaine-seeking was assessed under a within-session extinction/cue-induced reinstatement procedure. Estrous cycle was monitored in females to determine whether the effectiveness of wheel running varied by estrous cycle phase. Although females ran more than males, males were more sensitive to the effects of running and showed a dose-dependent decrease in cocaine-seeking with longer access resulting in greater suppression. The dose-effect relationship was less straightforward in females and access to both a locked and unlocked wheel decreased cocaine-seeking with effects dependent on estrous cycle phase. Notably, extended (6 and 24 h/day), but not limited (1 and 2 h/day) access to a wheel surmounted the heightened vulnerability observed in females during estrus. Taken together, our findings suggest that the effectiveness of wheel running is dose-, sex-, and estrous cycle-dependent.

  18. NTP-CERHR monograph on the potential human reproductive and developmental effects of bisphenol A.

    Science.gov (United States)

    Shelby, Michael D

    2008-09-01

    The National Toxicology Program (NTP) Center for the Evaluation of Risks to Human Reproduction (CERHR) conducted an evaluation of the potential for bisphenol A to cause adverse effects on reproduction and development in humans. The CERHR Expert Panel on Bisphenol A completed its evaluation in August 2007. CERHR selected bisphenol A for evaluation because of the: widespread human exposure; public concern for possible health effects from human exposures; high production volume; evidence of reproductive and developmental toxicity in laboratory animal studies Bisphenol A (CAS RN: 80-05-7) is a high production volume chemical used primarily in the production of polycarbonate plastics and epoxy resins. Polycarbonate plastics are used in some food and drink containers; the resins are used as lacquers to coat metal products such as food cans, bottle tops, and water supply pipes. To a lesser extent bisphenol A is used in the production of polyester resins, polysulfone resins, polyacrylate resins, and flame retardants. In addition, bisphenol A is used in the processing of polyvinyl chloride plastic and in the recycling of thermal paper. Some polymers used in dental sealants and tooth coatings contain bisphenol A. The primary source of exposure to bisphenol A for most people is assumed to occur through the diet. While air, dust, and water (including skin contact during bathing and swimming) are other possible sources of exposure, bisphenol A in food and beverages accounts for the majority of daily human exposure. The highest estimated daily intakes of bisphenol A in the general population occur in infants and children. The results of this bisphenol A evaluation are published in an NTP-CERHR Monograph that includes the (1) NTP Brief and (2) Expert Panel Report on the Reproductive and Developmental Toxicity of Bisphenol A. Additional information related to the evaluation process, including the peer review report for the NTP Brief and public comments received on the draft NTP

  19. The effects of polymer melt rheology on the replication of surface microstructures in isothermal moulding

    DEFF Research Database (Denmark)

    Eriksson, Torbjörn Gerhard; Rasmussen, Henrik Koblitz

    2005-01-01

    Series of isothermal compression moulding experiments were performed with a polycarbonate and a polystyrene melt in a hot press. The bottom plate in the hot press was equipped with a microstructured nickel insert. The insert contained 10 parallel, rectangularly shaped microchannels with a depth o...

  20. Scalable nanostructuring on polymer by a SiC stamp: optical and wetting effects

    DEFF Research Database (Denmark)

    Argyraki, Aikaterini; Lu, Weifang; Petersen, Paul Michael

    2015-01-01

    A method for fabricating scalable antireflective nanostructures on polymer surfaces (polycarbonate) is demonstrated. The transition from small scale fabrication of nanostructures to a scalable replication technique can be quite challenging. In this work, an area per print corresponding to a 2-inc...

  1. Effect of nightguard vital bleaching gel on the color stability of provisional restorative materials

    Directory of Open Access Journals (Sweden)

    Salwa Omar Bajunaid

    2016-01-01

    Conclusions: Composite-based provisional material showed highest color stability when exposed to vital tooth bleaching gel, whereas methacrylate-based material was the least color stable. Polycarbonate crowns were more color stable when exposed to 15% bleaching gel as opposed to 10% bleaching gel.

  2. Effects of Graphene Monolayer Coating on the Optical Performance of Remote Phosphors

    NARCIS (Netherlands)

    Yazdan Mehr, M.; Vollebregt, S.; van Driel, W.D.; Zhang, G.Q.

    2017-01-01

    A graphene monolayer has been successfully coated on one side of a bisphenol-A-polycarbonate (BPA-PC) plate, used as a substrate for remote phosphor applications in light-emitting diode (LED)-based products. Using a photoresist transferring method, graphene sheet has been coated on BPA-PC plates.

  3. Effects of Bisphenol A on the Ovarian Transcriptome of Two Small Fish Species

    Science.gov (United States)

    Bisphenol A (BPA) is a high production volume chemical widely used in the production of polycarbonate plastics, epoxy resins, and many other commercial products. BPA has long been characterized as a xenoestrogen, and recent work suggests potential additional modes of endocrine ac...

  4. Preparation and characterization of thermoplastic water-borne polycarbonate-based polyurethane dispersions and cast films

    Czech Academy of Sciences Publication Activity Database

    Serkis, Magdalena; Poreba, Rafal; Hodan, Jiří; Kredatusová, Jana; Špírková, Milena

    2015-01-01

    Roč. 132, č. 42 (2015), 42672_1-42672_14 ISSN 0021-8995 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : films * microscopy * nanoparticles Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.866, year: 2015

  5. Photochemistry of Bisphenol-A Based Polycarbonate: Early Detection of Photoproducts by Fluorescence Spectroscopy

    Science.gov (United States)

    1993-07-13

    Reactor with 300 nm lamps. Figure 15b Expanded view of Figure 15a. Figure 16 UV - Visible spectra of salicylic acid (OD = 0.2 at 310 nm) in DCM for 0, 5...Mississippi, Hattiesburg, Mississippi 39406-0076. ABSTRACT The utility of fluorescence spectroscopy in detection of salicylic acid and 2,Z- biphenol type...1). In the ensuing discussion, we will describe a procedure which allows for detection via fluorescence spectroscopy of salicylic acid as well as

  6. Impact Damage on a Thin Glass Plate with a Thin Polycarbonate Backing

    Science.gov (United States)

    2013-07-13

    skylight glazing and in windshields for automobile, train , and military vehicle. In order to design and improve glass laminates for protective appli- cations...explicit) finite element solution obtained by using Abaqus . The results for the bending deformation in the problem of elastic impact of a spherical rigid

  7. Polycyanurates and Polycarbonates Based on Eugenol: Alternatives to Thermosetting and Thermoplastic Polymers Based on Bisphenol A

    Science.gov (United States)

    2014-08-14

    Good Flame, Smoke, & Toxicity Characteristics Low Water Uptake with Near Zero Coefficient of Hygroscopic Expansion ∆ Distribution A. Approved...offer thermal stability and easy processing, but may not improve toughness as much as other methods . Thunga et al. – eXPRESS Polymer Letters Vol.8

  8. Numerical simulation of transient moisture and temperature distribution in polycarbonate and aluminum electronic enclosures

    DEFF Research Database (Denmark)

    Shojaee Nasirabadi, Parizad; Jabbaribehnam, Mirmasoud; Hattel, Jesper Henri

    2016-01-01

    The challenge of developing a reliable electronic product requires huge amounts of resources and knowledge. Temperature and thermal features directly affect the life of electronic products. Furthermore, moisture can be damaging for electronic components. Nowadays, computational fluid dynamics (CF...

  9. Employment of the polycarbonates Makrofol-DE and CR-39 for neutron radiography

    International Nuclear Information System (INIS)

    Pereira, Marco Antonio Stanojev

    2000-01-01

    The track-etch method was employed for Neutron Radiography purposes. The solid state nuclear track detectors Makrofol-DE and CR-39 together with a natural boron converter screen have been used as imaging systems. In order to determine their radiographic characteristics, the imaging systems were irradiated up to neutron exposures around 6x10 10 /cm 2 in a radiography facility installed at the IEA-R1 Nuclear Research Reactor and the detectors developed between 2 and 65 minutes. The main goal of this work was determine the radiography conditions for which the best contrast and resolution are obtained at the image. These conditions are: - Makrofol-DE: neutron exposure between 2x10 9 n/cm 2 and 2x10 10 n/cm 2 and developing time 6 minutes; CR-39: neutron exposure between 3x10 9 n/cm 2 and 2x10 10 n/cm 2 and developing time 25 minutes. The present results were compared with those ones determined to other track detectors, and discussed according to the theory of the image formation in solid state nuclear track detectors based on the optical properties of a single track. (author)

  10. Sensitivity of LEXAN polycarbonate to mass differences in the iron peak

    International Nuclear Information System (INIS)

    Gonzalo, M.; Vidal-Quadras, A.; Ortega, M.; Fernandez, F.; Baixeras, C.; Casas, M.; Sequeiros, J.; Medina, J.

    1982-01-01

    A systematic study of LEXAN response to mass differences for Z = 26 ions is presented. Over thirty iron tracks from Berkeley Heavy Ion accelerator have been characterized by a single parameter, namely its mean residual range. A semiempirical function relating etch-rate to restricted energy loss has been fitted to the experimental points and subsequently used to establish a charge and mass scale. It is concluded that an isotopic resolution better than σsub(A) = approximately 2 cannot be achieved with non-sensitized LEXAN. (author)

  11. Hydrolytic stability of polycarbonate-based polyurethane elastomers tested in physiologically simulated conditions

    Czech Academy of Sciences Publication Activity Database

    Serkis, Magdalena; Špírková, Milena; Poreba, Rafal; Hodan, Jiří; Kredatusová, Jana; Kubies, Dana

    2015-01-01

    Roč. 119, September (2015), s. 23-34 ISSN 0141-3910 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : polyurethane * elastomer * hydrolytic stability Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.120, year: 2015

  12. ESC resistance of commercial grade polycarbonates during exposure to butter and related chemicals

    DEFF Research Database (Denmark)

    Kjellander, Carina Koch; Nielsen, Tenna B; Ghanbari-Siahkali, Afshin

    2008-01-01

    differences in ESC resistance could be related to their structural or chemical properties. MALDI-TOF mass spectrometry revealed that Makrolon Rx:1805 contains a low molar mass material characterised as poly(propylene glycol)p, which was confirmed by ATR-FTIR and H-1 NMR. Some "non-absorbing" chemicals......, such as butter, cause the PCs to be less resistant to ESC under stress. The reason for this is that these chemicals and the PCs have sufficiently similar Hansen solubility parameters to allow surface conformational changes even though absorption is non-existent or extremely small. ATR-FTIR was used to detect...

  13. Polycarbonate crowns for primary teeth revisited: Restorative options, technique and case reports

    OpenAIRE

    Karthik Venkataraghavan; John Chan; Sandhya Karthik

    2014-01-01

    Esthetics by definition is the science of beauty - that particular detail of an animate or inanimate object that makes it appealing to the eye. In the modern, civilized, and cosmetically conscious world, well-contoured and well-aligned white teeth set the standard for beauty. Such teeth are not only considered attractive but are also indicative of nutritional health, self esteem, hygienic pride, and economic status. Numerous treatment approaches have been proposed to address the esthetics and...

  14. Adhesion enhancement of sol-gel coating on polycarbonate by heated impregnation treatment

    International Nuclear Information System (INIS)

    Wu, Linda Y.L.; Boon, L.; Chen, Z.; Zeng, X.T.

    2009-01-01

    The main limitation in using coated plastics for optical components, electronic applications and display systems is the softness of the substrate surfaces, which is responsible for the low impact and abrasion resistance and weak adhesion between the coating and the substrate. In this paper, we report a new strategy for surface pre-treatment of plastics using heated vacuum equipment and sol-gel materials to provide both chemical bonds and penetrated hard layer into the plastic surface to increase the overall performance of the coated plastic components. The heated vacuum treatment process involves: (1) surface cleaning and pore opening by heating and vacuum conditions, (2) impregnation of hydrolyzed hybrid precursor into polymer substrate under pressure and elevated temperature, (3) aminolysis of diffused precursor with surface to form chemical bonds and hardened surface layer, (4) formation of chemical bonds at treated surface with sol-gel hard coating. An impregnation depth of 1.5 μm was detected. Water contact angle dropped to below 40 o and roughness increased after treatment. These provided better adhesion by increased wettability and contact area. Much increased nanoindentation hardness and Young's modulus after impregnation provided a gradient in mechanical properties between soft substrate and hard sol-gel coating. The hardened substrate delays the plastic deformation in substrate during pencil scratch test, thereby preventing early gouge failure. Both the better adhesion and the delayed gouge failure contributed to the increased scratch resistance from 6B to 8H after sol-gel coating.

  15. Tensile Deformation and Adiabatic Heating in Post-Yield Response of Polycarbonate

    Science.gov (United States)

    2015-11-01

    adiabatic heat generation to be quantified. 2. Experiments ASTM D638-1018 standard polymer tensile dog-bone specimens were cut out of 5.75-mm-thick PC...sheet by waterjet . The specimen geometry is shown in Fig. 1 (in millimeters). The specimen edges were hand polished using wetted 600-grit sandpaper

  16. Effect of melatonin on the functional recovery from experimental traumatic compression of the spinal cord

    International Nuclear Information System (INIS)

    Schiaveto-de-Souza, A.; Silva, C.A. da; Defino, H.L.A.; Bel, E.A.Del

    2013-01-01

    Spinal cord injury is an extremely severe condition with no available effective therapies. We examined the effect of melatonin on traumatic compression of the spinal cord. Sixty male adult Wistar rats were divided into three groups: sham-operated animals and animals with 35 and 50% spinal cord compression with a polycarbonate rod spacer. Each group was divided into two subgroups, each receiving an injection of vehicle or melatonin (2.5 mg/kg, intraperitoneal) 5 min prior to and 1, 2, 3, and 4 h after injury. Functional recovery was monitored weekly by the open-field test, the Basso, Beattie and Bresnahan locomotor scale and the inclined plane test. Histological changes of the spinal cord were examined 35 days after injury. Motor scores were progressively lower as spacer size increased according to the motor scale and inclined plane test evaluation at all times of assessment. The results of the two tests were correlated. The open-field test presented similar results with a less pronounced difference between the 35 and 50% compression groups. The injured groups presented functional recovery that was more evident in the first and second weeks. Animals receiving melatonin treatment presented more pronounced functional recovery than vehicle-treated animals as measured by the motor scale or inclined plane. NADPH-d histochemistry revealed integrity of the spinal cord thoracic segment in sham-operated animals and confirmed the severity of the lesion after spinal cord narrowing. The results obtained after experimental compression of the spinal cord support the hypothesis that melatonin may be considered for use in clinical practice because of its protective effect on the secondary wave of neuronal death following the primary wave after spinal cord injury

  17. Effect of melatonin on the functional recovery from experimental traumatic compression of the spinal cord

    Energy Technology Data Exchange (ETDEWEB)

    Schiaveto-de-Souza, A. [Departamento de Morfofisiologia, Universidade Federal do Mato Grosso do Sul, Campo Grande, MS (Brazil); Silva, C.A. da [Departamento de Morfologia,Estomatologia e Fisiologia, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Defino, H.L.A. [Departamento de Orthopedia e Traumatologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Bel, E.A.Del [Departamento de Morfologia,Estomatologia e Fisiologia, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil)

    2013-04-12

    Spinal cord injury is an extremely severe condition with no available effective therapies. We examined the effect of melatonin on traumatic compression of the spinal cord. Sixty male adult Wistar rats were divided into three groups: sham-operated animals and animals with 35 and 50% spinal cord compression with a polycarbonate rod spacer. Each group was divided into two subgroups, each receiving an injection of vehicle or melatonin (2.5 mg/kg, intraperitoneal) 5 min prior to and 1, 2, 3, and 4 h after injury. Functional recovery was monitored weekly by the open-field test, the Basso, Beattie and Bresnahan locomotor scale and the inclined plane test. Histological changes of the spinal cord were examined 35 days after injury. Motor scores were progressively lower as spacer size increased according to the motor scale and inclined plane test evaluation at all times of assessment. The results of the two tests were correlated. The open-field test presented similar results with a less pronounced difference between the 35 and 50% compression groups. The injured groups presented functional recovery that was more evident in the first and second weeks. Animals receiving melatonin treatment presented more pronounced functional recovery than vehicle-treated animals as measured by the motor scale or inclined plane. NADPH-d histochemistry revealed integrity of the spinal cord thoracic segment in sham-operated animals and confirmed the severity of the lesion after spinal cord narrowing. The results obtained after experimental compression of the spinal cord support the hypothesis that melatonin may be considered for use in clinical practice because of its protective effect on the secondary wave of neuronal death following the primary wave after spinal cord injury.

  18. Effects of reprocessing on nanoalumina polymer composites

    Science.gov (United States)

    Huang, Chunchia

    The life cycle of reprocessed polymer nanocomposites is a critical factor associated with their growing use, but the limited work on reprocessing of nanocomposites has focused solely on the effects of organoclays. This research investigated of the structure and property changes during reprocessing of polypropylene (PP) and polycarbonate (PC) nanocomposites with 3 wt. % nanoalumina. Neat PP and PC were used as controls. Reprocessing of the neat polymers and nanocomposites produced no indication of oxidation (in FTIR), no changes in the glass transition temperature of PC and the melting temperatures of PP, and no changes in thermal stability (as measured using thermogravimetric analysis). Significant decreases, however, occurred in the melt viscosity of the materials. The introduction of nanoalumina during twin screw extrusion also produced a significant decrease in the viscosity and a 10°C decrease in the glass transition temperature of the PC nanocomposite. Color changes did not correspond to the chain scission in PP and PC; neat PP and PP composite yellowed, neat PC turned brown, and the PC nanocomposite did not change color. Dispersion of the nanoalumina in both PP and PC improved with repeated reprocessing, the crystallinity in the PP/nanoalumina composites remained constant. The Young's moduli of both the PP and PP/A12O3 nanocomposite were similar, whereas the Young's modulus values of the PC/A1 2O3 nanocomposite was slighted lower than that of the neat PC. In contrast, the elongations at break of the PP/A12O3 and PC/A12O3 nanocomposites were, respectively, 50% and 16% of the values measured for the neat resins. All modulus and elongation at break values, however, remained constant over five reprocessing cycles. This behavior suggests that the major degradation mechanism during reprocessing of neat PP and PP nanocomposites was thermal-mechanical polymer chain scission and that the nanoalumina enhanced this degradation in the PC/nanoalumina. This additional

  19. Effect of grape bunch sunlight exposure and UV radiation on phenolics and volatile composition of Vitis vinifera L. cv. Pinot noir wine.

    Science.gov (United States)

    Song, Jianqiang; Smart, Richard; Wang, Hua; Dambergs, Bob; Sparrow, Angela; Qian, Michael C

    2015-04-15

    The effect of canopy leaf removal and ultraviolet (UV) on Pinot noir grape and wine composition was investigated in this study. Limited basal leaf removal in the fruit zone was conducted, compared to shaded bunches. The UV exposure was controlled using polycarbonate screens to block UV radiation, and acrylic screens to pass the UV. The results showed that bunch sunlight and UV exposure significantly increased the Brix and pH in the grape juice, and increased substantially wine colour density, anthocyanins, total pigment, total phenolics and tannin content. Bunch sunlight and UV exposure affected terpene alcohols, C13-norisprenoids and other volatile composition of the wine differently. Sunlight exposure and UV resulted in increase of nerol, geraniol and citronellol but not linalool. Sunlight exposure slightly increased the concentration of β-ionone, but the increase was not statistically significant for UV treatment. Neither sunlight nor UV treatment showed any impact on the concentration of β-damascenone. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Next-generation resorbable polymer scaffolds with surface-precipitated calcium phosphate coatings.

    Science.gov (United States)

    Kim, Jinku; Magno, Maria Hanshella R; Ortiz, Ophir; McBride, Sean; Darr, Aniq; Kohn, Joachim; Hollinger, Jeffrey O

    2015-03-01

    Next-generation synthetic bone graft therapies will most likely be composed of resorbable polymers in combination with bioactive components. In this article, we continue our exploration of E1001(1k), a tyrosine-derived polycarbonate, as an orthopedic implant material. Specifically, we use E1001(1k), which is degradable, nontoxic, and osteoconductive, to fabricate porous bone regeneration scaffolds that were enhanced by two different types of calcium phosphate (CP) coatings: in one case, pure dicalcium phosphate dihydrate was precipitated on the scaffold surface and throughout its porous structure (E1001(1k) + CP). In the other case, bone matrix minerals (BMM) such as zinc, manganese and fluoride were co-precipitated within the dicalcium phosphate dihydrate coating (E1001(1k) + BMM). These scaffold compositions were compared against each other and against ChronOS (Synthes USA, West Chester, PA, USA), a clinically used bone graft substitute (BGS), which served as the positive control in our experimental design. This BGS is composed of poly(lactide co-ε-caprolactone) and beta-tricalcium phosphate. We used the established rabbit calvaria critical-sized defect model to determine bone regeneration within the defect for each of the three scaffold compositions. New bone formation was determined after 2, 4, 6, 8 and 12 weeks by micro-computerized tomography (μCT) and histology. The experimental tyrosine-derived polycarbonate, enhanced with dicalcium phosphate dihydrate, E1001(1k) + CP, supported significant bone formation within the defects and was superior to the same scaffold containing a mix of BMM, E1001(1k) + BMM. The comparison with the commercially available BGS was complicated by the large variability in bone formation observed for the laboratory preparations of E1001(1k) scaffolds. At all time points, there was a trend for E1001(1k) + CP to be superior to the commercial BGS. However, only at the 6-week time point did this trend reach statistical significance

  1. Protective effect of crocin on BPA-induced liver toxicity in rats through inhibition of oxidative stress and downregulation of MAPK and MAPKAP signaling pathway and miRNA-122 expression.

    Science.gov (United States)

    Vahdati Hassani, Faezeh; Mehri, Soghra; Abnous, Khalil; Birner-Gruenberger, Ruth; Hosseinzadeh, Hossein

    2017-09-01

    Bisphenol A (BPA) is an artificial environmental endocrine disrupting chemical and commonly used as a monomer of polycarbonate plastics and epoxy resins. The aim of the present study is to investigate the hepatoprotective effects of crocin, a constituent of saffron, against BPA-induced liver toxicity. We showed that treatment of male Wistar rats with 0.5 mg/kg BPA for 30 days increased the level of 8-isoprostane, decreased the level of reduced glutathione, elevated serum levels of aspartate aminotransferase, lactate dehydrogenase, triglyceride, and glucose, and induced periportal inflammation. Western blot results revealed that BPA increased the phosphorylation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK1/2), and mitogen-activated protein kinase-activated protein kinase (MAPKAPK), but not p38. BPA also reduced the Akt signaling activation and upregulated microRNA (miR-122) expression. Moreover, we showed here that crocin 20 mg/kg administration ameliorated liver damage and improved elevated levels of TG and liver enzymes of BPA-treated rats possibly though antioxidant activity, downregulation of miR-122 transcript level and lowering the phosphorylation of JNK, ERK1/2, and MAPKAPK and subsequently their activities. Overall, the findings suggest that crocin possesses hepatoprotective effects against BPA-induced liver toxicity by enhancing the antioxidative defense system and regulation of important signaling pathway activities and miR-122 expression. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Effect of wheel-running during abstinence on subsequent nicotine-seeking in rats

    Science.gov (United States)

    Sanchez, Victoria; Moore, Catherine F; Brunzell, Darlene H; Lynch, Wendy J

    2013-01-01

    Rationale Exercise appears to be a promising non-pharmacological treatment for nicotine addiction that may be useful for the vulnerable adolescent population. Objectives To determine if wheel running, an animal model of aerobic exercise, during an abstinence period would decrease subsequent nicotine-seeking in rats that had extended access to nicotine self-administration during adolescence. Methods Male adolescent rats (n = 55) were trained to self-administer saline or nicotine infusions (5 or 10 μg/kg) under a fixed ratio 1 schedule with a maximum of 20 infusions/day beginning on postnatal day 30. After 5 days, access was extended to 23-hr/day with unlimited infusions for a total of 10 days. After the last self-administration session, rats were moved to polycarbonate cages for a 10-day abstinence period where they either had access to a locked or unlocked running wheel for 2-hr/day. Nicotine-seeking was examined following the 10th day of abstinence under a within-session extinction/cue-induced reinstatement paradigm. Results Intake was higher at the 10 μg/kg dose as compared to the 5 μg/kg dose; however, intake did not differ within doses prior to wheel assignment. Compared to saline controls, rats that self-administered nicotine at either dose showed a significant increase in drug-seeking during extinction, and consistent with our hypothesis, exercise during abstinence attenuated this effect. Nicotine led to modest, but significant levels of cue-induced reinstatement; however, in this adolescent-onset model, levels were variable and not affected by exercise. Conclusions Exercise may effectively reduce relapse vulnerability for adolescent-onset nicotine addiction. PMID:23371488

  3. Investigations of the thermal treatment effect on the generation of cadmium sulfide clusters in polymeric films

    International Nuclear Information System (INIS)

    Stanculescu, Anca; Socol, M.; Stanculescu, F.

    2002-01-01

    In the last years a special interest has been paid to the field of nanometer-sized semiconductor compound crystalline clusters synthesized in different matrix (inorganic or organic), due to their special physical and chemical properties intermediate between the molecular and bulk limits. To obtain the thin film samples of CdS particles embedded in a polymeric transparent matrix, as bisphenol A polycarbonate, we followed a process containing three important steps: preparation of the so-called 'mother solution', film deposition and thermal treatment. The samples obtained after the first two steps were heat treated at different temperatures (90 deg. C and 150 deg. C) for 0.5 h, 1 h and 1.5 h, and we have analyzed the influence of these parameters on the film quality using UV-VIS spectrophotometric methods. This paper presents a study of the influence of the thermal treatment on the CdS clusters' generation process and film quality and homogeneity. The parameters of the processing procedure of the polymeric film, as the cooling rate, have a great influence on the rate of germination and development of the crystalline phase. A slow cooling rate is a more favorable process for CdS clusters' formation, indicated .by structured features of the fundamental absorption situated between 350-450 nm. When the temperature for thermal treatment increases to 90 deg. C a sharp rise and a shift to shorter wavelengths of the absorption onset edge was observed. This shift proves the existence of a weak quantum confinement effects. We concluded that these two parameters have some equivalent effects on the CdS clusters' generation in polymeric matrix. Varying the treatment duration with a fixed temperature produces similar results as the fixed duration, varied temperature treatment. (authors)

  4. Load and depth sensing indentation as a tool to monitor a gradient in the mechanical properties across a polymer coating: A study of physical and chemical aging effects

    NARCIS (Netherlands)

    Boersma, A.; Soloukhin, V.A.; Brokken-Zijp, J.C.M.; With, G. de

    2004-01-01

    Load and depth sensing indentation has been used to characterize the elastic modulus and hardness of various polycarbonate films. This analytical technique is shown to be extremely suitable for the determination of gradients in these mechanical properties. Furthermore, it is demonstrated that such a

  5. The Effect of surface Treatment of Alumina NanoParticles with a Silane Coupling Agent on the Mechanical Properties of Polymer Nanocomposites

    Science.gov (United States)

    Amirchakhmaghi, S.; Nia, A. Alavi; Azizpour, G.; Bamdadi, H.

    2015-07-01

    Surface-treated and untreated alumina nanoparticles were mixed with a polycarbonate matrix at different weight percentages and the mechanical properties of the nanocomposites produced were determined by subjecting them to quasi-static tension and Charpy impact tests. The results obtained showed that the surface treatment of nanoparticles had improved their mechanical properties.

  6. Effect of growth temperature, surface type and incubation time on the resistance of Staphylococcus aureus biofilms to disinfectants.

    Science.gov (United States)

    Abdallah, Marwan; Chataigne, Gabrielle; Ferreira-Theret, Pauline; Benoliel, Corinne; Drider, Djamel; Dhulster, Pascal; Chihib, Nour-Eddine

    2014-03-01

    The goal of this study was to investigate the effect of the environmental conditions such as the temperature change, incubation time and surface type on the resistance of Staphylococcus aureus biofilms to disinfectants. The antibiofilm assays were performed against biofilms grown at 20 °C, 30 °C and 37 °C, on the stainless steel and polycarbonate, during 24 and 48 h. The involvement of the biofilm matrix and the bacterial membrane fluidity in the resistance of sessile cells were investigated. Our results show that the efficiency of disinfectants was dependent on the growth temperature, the surface type and the disinfectant product. The increase of growth temperature from 20 °C to 37 °C, with an incubation time of 24 h, increased the resistance of biofilms to cationic antimicrobials. This change of growth temperature did not affect the major content of the biofilm matrix, but it decreased the membrane fluidity of sessile cells through the increase of the anteiso-C19 relative amount. The increase of the biofilm resistance to disinfectants, with the rise of the incubation time, was dependent on both growth temperature and disinfectant product. The increase of the biofilm age also promoted increases in the matrix production and the membrane fluidity of sessile cells. The resistance of S. aureus biofilm seems to depend on the environment of the biofilm formation and involves both extracellular matrix and membrane fluidity of sessile cells. Our study represents the first report describing the impact of environmental conditions on the matrix production, sessile cells membrane fluidity and resistance of S. aureus biofilms to disinfectants.

  7. Computer simulation and experiments to investigate the effects of frequency-dependent attenuation and dispersion on speed-of-sound estimates in cancellous bone

    Science.gov (United States)

    Wear, Keith A.

    2001-05-01

    Many studies have demonstrated that time-domain speed-of- sound (SOS) measurement sin calcaneus are predictive of osteoporotic fracture risk. However there is a lack of standardization for this measurement. Consequently, different investigators using different measurement systems and analysis algorithms obtain disparate quantitative values for calcaneal SOS, impairing and often precluding meaningful comparison and/or pooling of measurements. A numerical method has been developed to model the effects of frequency- dependent attenuation and dispersion on transit-time-based SOS estimates. The numerical technique is based on a previously developed linear system analytic model for Gaussian pulses propagating through linearly attenuating, weakly dispersive media. The numerical approach is somewhat more general in that it can be used to predict the effects of arbitrary pulse shapes and dispersion relationships. The numerical technique however utilizes several additional assumptions (compared with the analytic model) which would be required for the practical task of correcting existing clinical databases. These include a single dispersion relationship for all calcaneus samples, a simple linear model relating phase velocity to broadband ultrasonic attenuation, and a constant calcaneal thickness. Measurements on a polycarbonate plate and thirty human calcaneus samples were in good quantitative agreement with numerical predictions. In addition, the numerical approach predicts that in cancellous bone, frequency-dependent attenuation tends to be a greater contributor to variations in transit-time-based SOS estimates than dispersion. This approach may be used to adjust previously acquired individual measurements so that SOS data recorded with different devices using different algorithms may be compared in a meaningful fashion.

  8. The effects of postnatal exposure to low-dose bisphenol-A on activity-dependent plasticity in the mouse sensory cortex

    Science.gov (United States)

    Kelly, Emily A.; Opanashuk, Lisa A.; Majewska, Ania K.

    2014-01-01

    Bisphenol-A (BPA) is a monomer used in the production of polycarbonate plastics, epoxies and resins and is present in many common household objects ranging from water bottles, can linings, baby bottles, and dental resins. BPA exposure has been linked to numerous negative health effects throughout the body, although the mechanisms of BPA action on the developing brain are still poorly understood. In this study, we sought to investigate whether low dose BPA exposure during a developmental phase when brain connectivity is being organized can cause long-term deleterious effects on brain function and plasticity that outlast the BPA exposure. Lactating dams were orally exposed to 25 μg/kg/day of BPA (one half the U.S. Environmental Protection Agency’s 50 μg/kg/day rodent dose reference) or vehicle alone from postnatal day (P)5 to P21. Pups exposed to BPA in their mother’s milk exhibited deficits in activity-dependent plasticity in the visual cortex during the visual critical period (P28). To determine the possible mechanisms underlying BPA action, we used immunohistochemistry to examine histological markers known to impact cortical maturity and developmental plasticity and quantified cortical dendritic spine density, morphology, and dynamics. While we saw no changes in parvalbumin neuron density, myelin basic protein expression or microglial density in BPA-exposed animals, we observed increases in spine density on apical dendrites in cortical layer five neurons but no significant alterations in other morphological parameters. Taken together our results suggest that exposure to very low levels of BPA during a critical period of brain development can have profound consequences for the normal wiring of sensory circuits and their plasticity later in life. PMID:25374513

  9. Generating Electricity by Harnessing Air That Flows Around a Skyscraper by Using Bernoulli's Principle And The Venturi Effect w/Special Emphasis on Biomimicry

    Science.gov (United States)

    Pizzolato, R.

    2017-12-01

    Can skyscrapers become carbon neutral using wind that flows around them to power wind turbines? I say YES! To test this idea, I constructed a venturi to capture wind flowing around a skyscraper by applying Bernoulli's Principle and the Venturi Effect to power vertical axis wind turbines (VAWT) to generate electricity. The model was constructed from polycarbonate. Turbine blades (45°&60°) carved from balsa wood with square edges, airfoils, and trailing edge tubercles (Humpback whales-biomimicry) were tested in a wind tunnel. Output was measured using Vernier's Logger Pro 3.12 software, energy and wind sensors. Voltage (mV), current (mA), power (mW) and total energy (mJ) produced at winds speeds of 3.9, 5, 7.5 and 10 m/s were recorded. 10 trials were performed for each blade angle and each blade design for a total of 240 trials. Trials were 100 seconds long and recorded at a rate of 10 measurements/second. The blades that showed the largest %Δ in total average energy output (mJ) were the 60° airfoil blades w/ tubercles on the trailing edge (20,490 mJ) when compared to 60° square edged blades (7,021 mJ). The trend of the data showed that the airfoils w/tubercles (45° & 60°) outperformed all the other blade designs at wind speeds of 7.5 m/s and 10 m/s. Also, the 45° airfoil w/tubercles produced the highest output of 25,136 mJ! This was possibly due to the improved aerodynamics of the tubercle blades which led to improvements in lift and a reduction in drag. The data shows that turbine blades that incorporate biomimicry in their design result in more efficient power output. Through biomimicry, it is possible to efficiently generate electricity with a skyscraper and reduce our dependence upon fossil fuels!

  10. Sex differences in the effect of wheel running on subsequent nicotine-seeking in a rat adolescent-onset self-administration model.

    Science.gov (United States)

    Sanchez, Victoria; Moore, Catherine F; Brunzell, Darlene H; Lynch, Wendy J

    2014-04-01

    Wheel running attenuates nicotine-seeking in male adolescent rats; however, it is not known if this effect extends to females. To determine if wheel running during abstinence would differentially attenuate subsequent nicotine-seeking in male and female rats that had extended access to nicotine self-administration during adolescence. Male (n = 49) and female (n = 43) adolescent rats self-administered saline or nicotine (5 μg/kg) under an extended access (23-h) paradigm. Following the last self-administration session, rats were moved to polycarbonate cages for an abstinence period where they either had access to a locked or unlocked running wheel for 2 h/day. Subsequently, nicotine-seeking was examined under a within-session extinction/cue-induced reinstatement paradigm. Due to low levels of nicotine-seeking in females in both wheel groups, additional groups were included that were housed without access to a running wheel during abstinence. Females self-administered more nicotine as compared to males; however, within males and females, intake did not differ between groups prior to wheel assignment. Compared to saline controls, males and females that self-administered nicotine showed a significant increase in drug-seeking during extinction. Wheel running during abstinence attenuated nicotine-seeking during extinction in males. In females, access to either locked or unlocked wheels attenuated nicotine-seeking during extinction. While responding was reinstated by cues in both males and females, levels were modest and not significantly affected by exercise in this adolescent-onset model. While wheel running reduced subsequent nicotine-seeking in males, access to a wheel, either locked or unlocked, was sufficient to suppress nicotine-seeking in females.

  11. Study on effect of cubic- and tetragonal phased BaTiO{sub 3} on the electrical and thermal properties of polymeric nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Thanki, A.A.; Goyal, R.K., E-mail: rkgoyal72@yahoo.co.in

    2016-11-01

    Polymer matrix nanocomposites based on polycarbonate (PC) and nanosized-cubic/tetragonal phases of barium titanate (BaTiO{sub 3}) were fabricated using a solution method followed by hot pressing. The content of both cubic- and tetragonal phased BaTiO{sub 3} was varied from 0 to 50 wt%. For a given weight fraction, the dielectric constant of the nanocomposites containing tetragonal BaTiO{sub 3} is more than those of cubic BaTiO{sub 3} filled nanocomposites. Moreover, cubic BaTiO{sub 3}/PC nanocomposites showed significantly lower dissipation factor than those of tetragonal BaTiO{sub 3}/PC nanocomposites. The dielectric constant of the nanocomposites was found to be frequency-independent. The microhardness of the nanocomposites increased with increase in the BaTiO{sub 3} content (both cubic- and tetragonal-phased) compared to the pure matrix. Scanning electron microscopy showed better dispersion and good interaction of the tetragonal BaTiO{sub 3} nanoparticles in the matrix. The addition of cubic BaTiO{sub 3} nanoparticles significantly reduced the thermal stability of the nanocomposites compared to matrix while the addition of tetragonal BaTiO{sub 3} nanoparticles decreased it slightly. The glass transition temperature of the cubic BaTiO{sub 3}/PC nanocomposites decreased significantly, whereas it reduced slightly for the tetragonal BaTiO{sub 3}/PC nanocomposites. - Highlights: • The effect of cubic-BaTiO{sub 3} and tetragonal-BaTiO{sub 3} nanoparticles were studied. • Cubic-BaTiO{sub 3} nanoparticles showed better microhardness. • Tetragonal-BaTiO{sub 3} nanoparticles showed better dielectric and thermal properties. • Frequency independent dielectric constants of the nanocomposites were observed.

  12. Anxiogenic effects of developmental bisphenol A exposure are associated with gene expression changes in the juvenile rat amygdala and mitigated by soy.

    Directory of Open Access Journals (Sweden)

    Heather B Patisaul

    Full Text Available Early life exposure to Bisphenol A (BPA, a component of polycarbonate plastics and epoxy resins, alters sociosexual behavior in numerous species including humans. The present study focused on the ontogeny of these behavioral effects beginning in adolescence and assessed the underlying molecular changes in the amygdala. We also explored the mitigating potential of a soy-rich diet on these endpoints. Wistar rats were exposed to BPA via drinking water (1 mg/L from gestation through puberty, and reared on a soy-based or soy-free diet. A group exposed to ethinyl estradiol (50 µg/L and a soy-free diet was used as a positive estrogenic control. Animals were tested as juveniles or adults for anxiety-like and exploratory behavior. Assessment of serum BPA and genistein (GEN, a soy phytoestrogen, confirmed that internal dose was within a human-relevant range. BPA induced anxiogenic behavior in juveniles and loss of sexual dimorphisms in adult exploratory behavior, but only in the animals reared on the soy-free diet. Expression analysis revealed a suite of genes, including a subset known to mediate sociosexual behavior, associated with BPA-induced juvenile anxiety. Notably, expression of estrogen receptor beta (Esr2 and two melanocortin receptors (Mc3r, Mc4r were downregulated. Collectively, these results show that behavioral impacts of BPA can manifest during adolescence, but wane in adulthood, and may be mitigated by diet. These data also reveal that, because ERβ and melanocortin receptors are crucial to their function, oxytocin/vasopressin signaling pathways, which have previously been linked to human affective disorders, may underlie these behavioral outcomes.

  13. Bisphenol A in dental sealants and its estrogen like effect

    OpenAIRE

    Rathee, Manu; Malik, Poonam; Singh, Jyotirmay

    2012-01-01

    Bisphenol A or BPA-based epoxy resins are widely used in the manufacture of commercial products, including dental resins, polycarbonate plastics, and the inner coating of food cans. BPA is a precursor to the resin monomer Bis-GMA. During the manufacturing process of Bis-GMA dental sealants, Bisphenol A (BPA) might be present as an impurity or as a degradation product of Bis-DMA through esterases present in saliva. Leaching of these monomers from resins can occur during the initial setting per...

  14. Selection and fabrication of a non-woven polycarbonate urethane cover for a tissue engineered airway stent

    NARCIS (Netherlands)

    Chen, Weiluan; Clauser, Johanna; Thiebes, Anja Lena; McGrath, Donnacha J.; McHugh, Peter E.; Steinseifer, Ulrich; Jockenhoevel, Stefan; Hennink, Wim E.; Kok, Robbert Jan

    2016-01-01

    One of the major problems in end-stage bronchotracheal cancer is stenosis of the upper airways, either due to luminal ingrowth of the tumor or mucus plugging. Airway stents that suppress tumor ingrowth and sustain mucociliary transport can alleviate these problems in end-stage bronchial cancer. We

  15. The impact of conditions mimicking physiological environment on the thermal stability of aliphatic polycarbonate-based polyurethane elastomers

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Kredatusová, Jana; Hodan, Jiří

    2017-01-01

    Roč. 128, č. 3 (2017), s. 1699-1709 ISSN 1388-6150 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : polyurethane * thermal stability * thermogravimetric analysis Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 1.953, year: 2016

  16. Aliphatic polycarbonate-based polyurethane nanostructured materials. The influence of the composition on thermal stability and degradation

    Czech Academy of Sciences Publication Activity Database

    Poreba, Rafal; Špírková, Milena; Pavličević, J.; Budinski-Simendic, J.; Mészáros Szécsényi, K.; Hollo, B.

    2014-01-01

    Roč. 58, March (2014), s. 496-501 ISSN 1359-8368 R&D Projects: GA ČR GAP108/10/0195 Institutional support: RVO:61389013 Keywords : polymer-matrix composites (PMCs) * thermal properties * thermal analysis Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.983, year: 2014

  17. The influence of montmorillonite and bentonite addition on thermal properties of polyurethanes based on aliphatic polycarbonate diols

    Czech Academy of Sciences Publication Activity Database

    Pavličević, J.; Špírková, Milena; Strachota, Adam; Meszaros Szecsenyi, K.; Lazić, N.; Budinski-Simendic, J.

    2010-01-01

    Roč. 509, 1/2 (2010), s. 73-80 ISSN 0040-6031 R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : segmented polyurethanes * thermal stability * elastomers Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.908, year: 2010

  18. The influence of ZnO nanoparticles on thermal and mechanical behavior of polycarbonate-based polyurethane composites

    Czech Academy of Sciences Publication Activity Database

    Pavličević, J.; Špírková, Milena; Bera, O.; Jovičić, M.; Pilić, B.; Baloš, S.; Budinski-Simendic, J.

    2014-01-01

    Roč. 60, April (2014), s. 673-679 ISSN 1359-8368 R&D Projects: GA ČR GAP108/10/0195 Institutional support: RVO:61389013 Keywords : polymer–matrix composites (PMCs) * mechanical properties * thermal analysis Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.983, year: 2014

  19. Effects of ion beam treatment on atomic and macroscopic adhesion of copper to different polymer materials

    Science.gov (United States)

    Zaporojtchenko, V.; Zekonyte, J.; Faupel, F.

    2007-12-01

    Low-energy ion irradiation of polymer induces different phenomena in the near surface layer, which effect strongly the metal-polymer interface formation and promotes adhesion of polymers to metals. Low-energy argon and oxygen ion beams were used to alter the chemical and physical properties of different polymers (PS (polystyrene), PαMS (poly(α-methylstyrene), BPA-PC (bisphenol-A-polycarbonate) and PMMA (poly(methyl methacrylate)), in order to understand the adhesion phenomena between a deposited Cu layer and the polymers. The resulting changes were investigated by various techniques including X-ray photoelectron spectroscopy, measurements of the metal condensation coefficient and a new technique to measure cross-linking at the polymer surface. Two types of practical adhesion strengths of Cu-polymer systems, measured using 90° peel tests, were observed: (i) peel strength increased at low ion fluences, reached a maximum and then decreased after prolonged treatment and (ii) no improvement in the peel strength on treated polymer surfaces was recorded. The improvement in the metal-polymer adhesion in the ion fluence range of 10 13-10 15 cm -2 is attributed to the creation of a large density of new adsorption sites resulting in a larger contact area and incorporation of chemically active groups that lead to increased interaction between metal and polymer by metal-oxygen-polymer species formation. XPS analysis of peeled-off surfaces showed that in most cases the failure location changed from interfacial for untreated polymers to cohesive failure in the polymer for treated surfaces. These observations and measurements of the metal condensation coefficients suggest that bonding is improved at the metal-polymer interface for all metal-polymer systems. However, the decrease in the peel strength at high ion fluences is attributed to the formation of a weak boundary layer in polymers. The correlation between sputter rate of polymers and altering in the peel strength for

  20. Effects of ion beam treatment on atomic and macroscopic adhesion of copper to different polymer materials

    International Nuclear Information System (INIS)

    Zaporojtchenko, V.; Zekonyte, J.; Faupel, F.

    2007-01-01

    Low-energy ion irradiation of polymer induces different phenomena in the near surface layer, which effect strongly the metal-polymer interface formation and promotes adhesion of polymers to metals. Low-energy argon and oxygen ion beams were used to alter the chemical and physical properties of different polymers (PS (polystyrene), PαMS (poly(α-methylstyrene), BPA-PC (bisphenol-A-polycarbonate) and PMMA (poly(methyl methacrylate)), in order to understand the adhesion phenomena between a deposited Cu layer and the polymers. The resulting changes were investigated by various techniques including X-ray photoelectron spectroscopy, measurements of the metal condensation coefficient and a new technique to measure cross-linking at the polymer surface. Two types of practical adhesion strengths of Cu-polymer systems, measured using 90 o peel tests, were observed: (i) peel strength increased at low ion fluences, reached a maximum and then decreased after prolonged treatment and (ii) no improvement in the peel strength on treated polymer surfaces was recorded. The improvement in the metal-polymer adhesion in the ion fluence range of 10 13 -10 15 cm -2 is attributed to the creation of a large density of new adsorption sites resulting in a larger contact area and incorporation of chemically active groups that lead to increased interaction between metal and polymer by metal-oxygen-polymer species formation. XPS analysis of peeled-off surfaces showed that in most cases the failure location changed from interfacial for untreated polymers to cohesive failure in the polymer for treated surfaces. These observations and measurements of the metal condensation coefficients suggest that bonding is improved at the metal-polymer interface for all metal-polymer systems. However, the decrease in the peel strength at high ion fluences is attributed to the formation of a weak boundary layer in polymers. The correlation between sputter rate of polymers and altering in the peel strength for

  1. Effects of BPA on global DNA methylation and global histone 3 lysine modifications in SH-SY5Y cells: An epigenetic mechanism linking the regulation of chromatin modifiying genes.

    Science.gov (United States)

    Senyildiz, Mine; Karaman, Ecem Fatma; Bas, Serap Sancar; Pirincci, Pelin Arda; Ozden, Sibel

    2017-10-01

    Bisphenol A (BPA), an estrogenic endocrine disruptor, is widely used in the production of polycarbonate plastic and epoxy resins, resulting in high risk on human health. In present study we aimed to investigate the effects of BPA on global and gene specific DNA methylation, global histone modifications and regulation of chromatin modifiying enzymes in human neuroblastoma cells (SH-SY5Y). Cells were treated with BPA at 0.1, 1 and 10μM concentrations for 48 and 96h. IC 50 value of BPA was determined as 183 and 129μM in SH-SY5Y cells after 24h by MTT and NRU tests, respectively. We observed significant alterations on the 5-mC% levels (1.3 fold) and 5-hmC% levels (1.67 fold) after 10μM of BPA for 96h. Significant decrease was identified in H3K9me3 and H3K9ac after 10μM of BPA for 96h while decrease was observed in H3K4me3 at 10μM of BPA for 48h. Alterations were observed in chromatin modifiying genes including G9a, EZH2, SETD8, SETD1A, HAT1, SIRT1, DNMT1, RIZ1 and Suv39h1 after 96h of BPA exposure. Taken together, this study suggests that BPA might modulate the epigenetic regulators which would be key molecular events in the toxicity of endocrine disrupting chemicals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Effect of surfactant species and electrophoretic medium composition on the electrophoretic behavior of neutral and water-insoluble linear synthetic polymers in nonaqueous capillary zone electrophoresis.

    Science.gov (United States)

    Fukai, Nao; Kitagawa, Shinya; Ohtani, Hajime

    2017-07-01

    We have recently demonstrated the separation of neutral and water-insoluble linear synthetic polymers in nonaqueous capillary zone electrophoresis (NACZE) using a cationic surfactant of cetyltrimethylammonium chloride (CTAC). In this study, eight ionic surfactants were investigated for the separation of four synthetic polymers (polystyrene, polymethylmethacrylates, polybutadiene, and polycarbonate); only three surfactants (CTAC, dimethyldioctadecylammonium bromide, and sodium dodecylsulfate) caused their separation. The order of the interaction between the polymers and the surfactants depended on both the surfactant species and the composition of the electrophoretic medium. Their investigation revealed that the separation is majorly affected by the hydrophobic interactions between the polymers and the ionic surfactants. In addition, the electrophoretic behavior of polycarbonate suggested that electrostatic interaction also affects the selectivity of the polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Color formation study of irradiated polymers by electron beam

    International Nuclear Information System (INIS)

    Nardi, Daniela Teves

    2004-01-01

    Color formation on national and commercial polymers (polymethyl methacrylate, polystyrene and polycarbonate) irradiated by electrons beam was investigated by colorimetry (CIELab), electron spectroscopy resonance (ESR), photoacoustic infrared spectroscopy (FTIR-PAS) and differential exploratory calorimetry (DSC). The heat effect on colorimetric properties was investigated after heating (110 deg C for 1 hour) of irradiated polymers at 150 kGy. The rule of oxygen in colorimetric properties of irradiated polycarbonate was investigated in the air presence and absence (p = 10 -3 mmHg). The visual aspect did not agree with colorimetric parameters only for polycarbonate. Yellow color and darkness were induced by radiation for all studied polymers varying only the intensity and behavior in function of post-irradiation time and heating. Polymethyl methacrylate and polystyrene ESR spectra showed that radicals could be responsible by yellow color centers. Wherever, in polycarbonate, color centers were not due radical species. The nature of color centers for any studied polymer was not study by FTIR-PAS because there were no changes in FTIR-PAS spectra neither in function of dose nor heating. Polycarbonate was the most radiosensible and polystyrene was the most radioresistant of all studied polymers in concern of colorimetric properties. (author)

  4. Drastic modification of the piezoresistive behavior of polymer nanocomposites by using conductive polymer coatings

    KAUST Repository

    Ventura, Isaac Aguilar

    2015-07-21

    We obtained highly conductive nanocomposites by adding conductive polymer poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOT/PSS)-coated carbon nanotubes (CNTs) to pristine insulating Polycarbonate. Because the PEDOT/PSS ensures efficient charge transfer both along and between the CNTs, we could attribute the improvement in electrical conductivity to coating. In addition to improving the electrical conductivity, the coating also modified the piezoresistive behavior of the nanocomposites compared to the material with pristine uncoated CNTs: whereas CNT/Polycarbonate samples exhibited a very strong piezoresistive effect, PEDOT/PSS-coated MWCNT/Polycarbonate samples exhibited very little piezoresistivity. We studied this change in piezoresistive behavior in detail by investigating various configurations of filler content. We investigated how this observation could be explained by changes in the microstructure and in the conduction mechanism in the interfacial regions between the nanofillers. Our study suggests that tailoring the piezoresistive response to specific application requirements is possible.

  5. CLARITY-BPA: Effects of chronic bisphenol A exposure on the immune system: Part 2 - Characterization of lymphoproliferative and immune effector responses by splenic leukocytes.

    Science.gov (United States)

    Li, Jinpeng; Bach, Anthony; Crawford, Robert B; Phadnis-Moghe, Ashwini S; Chen, Weimin; D'Ingillo, Shawna; Kovalova, Natalia; Suarez-Martinez, Jose E; Zhou, Jiajun; Kaplan, Barbara L F; Kaminski, Norbert E

    2018-03-01

    Bisphenol A (BPA) is commonly used in the manufacturing of a wide range of consumer products, including polycarbonate plastics, epoxy resin that lines beverage and food cans, and some dental sealants. Consumption of food and beverages containing BPA represents the primary route of human BPA exposure, which is virtually ubiquitous. An increasing number of studies have evaluated the effects of BPA on immune responses in laboratory animals that have reported a variety of effects some of which have been contradictory. To address the divergent findings surrounding BPA exposure, a comprehensive chronic treatment study of BPA was conducted in Sprague-Dawley rats, termed the Consortium Linking Academic and Regulatory Insights on Toxicity of BPA (CLARITY-BPA). As a participant in the CLARITY-BPA project, our studies evaluated the effects of BPA on a broad range of immune function endpoints using spleen cells isolated from BPA or vehicle treated rats. This comprehensive assessment included measurements of lymphoproliferation in response to mitogenic stimuli, immunoglobulin production by B cells, and cellular activation of T cells, NK cells, monocytes, granulocytes, macrophages and dendritic cells. In total, 630 different measurements in BPA treated rats were performed of which 35 measurements were statistically different from vehicle controls. The most substantive alteration associated with BPA treatment was the augmentation of lymphoproliferation in response to pokeweed mitogen stimulations in 1 year old male rats, which was also observed in the reference estrogen ethinyl estradiol treated groups. With the exception of the aforementioned, the statistically significant changes associated with BPA treatment were mostly sporadic and not dose-dependent with only one out of five BPA dose groups showing a statistical difference. In addition, the observed BPA-associated alterations were mostly moderate in magnitude and showed no persistent trend over the one-year time period

  6. Effects of bias voltage on the properties of ITO films prepared on polymer substrates

    International Nuclear Information System (INIS)

    Lee, Jaehyeong; Jung, Hakkee; Lim, Donggun; Yang, Keajoon; Song, Woochang; Yi, Junsin

    2005-01-01

    The ITO (indium tin oxide) thin films were deposited on acryl, glass, PET, and poly-carbonate substrates by DC reactive magnetron sputtering. The bias voltage was changed from -20 to -80 V. As the bias voltage increased, the deposition rate of ITO films decreased regardless of substrate types. The roughness of the films on PET increased with the bias voltage. The study demonstrated that the bias improved the electrical and optical properties of ITO films regardless of substrate types. The lowest electrical resistivity of 5.5x10 -4 no. OMEGAno. -cm and visible transmittance of about 80% were achieved by applying a negative bias of -60 V

  7. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    pp 569-573. Optical properties of d.c. magneto sputtered tantalum and titanium nanostructure thin film metal hydrides ... Effect of Ba(Ti(0.9)Sn0.1)O3 ceramic doping on optical, thermal and dielectric properties of polycarbonate host .... Effect of carbon on mechanical properties of powder-processed Fe–0.35%P alloys.

  8. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Vickers microhardness indentation technique has been employed to detect the photoplastic effect in the transparent polycarbonate specimens in darkness and under mercury illumination. For low applied loads, the hardening of specimens under illumination confirms the positive photoplastic effect that causes ...

  9. Melt processing and property testing of a model system of plastics contained in waste from electrical and electronic equipment.

    Science.gov (United States)

    Triantou, Marianna I; Tarantili, Petroula A; Andreopoulos, Andreas G

    2015-05-01

    In the present research, blending of polymers used in electrical and electronic equipment, i.e. acrylonitrile-butadiene-styrene terpolymer, polycarbonate and polypropylene, was performed in a twin-screw extruder, in order to explore the effect process parameters on the mixture properties, in an attempt to determine some characteristics of a fast and economical procedure for waste management. The addition of polycarbonate in acrylonitrile-butadiene-styrene terpolymer seemed to increase its thermal stability. Also, the addition of polypropylene in acrylonitrile-butadiene-styrene terpolymer facilitates its melt processing, whereas the addition of acrylonitrile-butadiene-styrene terpolymer in polypropylene improves its mechanical performance. Moreover, the upgrading of the above blends by incorporating 2 phr organically modified montmorillonite was investigated. The prepared nanocomposites exhibit greater tensile strength, elastic modulus and storage modulus, as well as higher melt viscosity, compared with the unreinforced blends. The incorporation of montmorillonite nanoplatelets in polycarbonate-rich acrylonitrile-butadiene-styrene terpolymer/polycarbonate blends turns the thermal degradation mechanism into a two-stage process. Alternatively to mechanical recycling, the energy recovery from the combustion of acrylonitrile-butadiene-styrene terpolymer/polycarbonate and acrylonitrile-butadiene-styrene terpolymer/polypropylene blends was recorded by measuring the gross calorific value. Comparing the investigated polymers, polypropylene presents the higher gross calorific value, followed by acrylonitrile-butadiene-styrene terpolymer and then polycarbonate. The above study allows a rough comparative evaluation of various methodologies for treating plastics from waste from electrical and electronic equipment. © The Author(s) 2015.

  10. Pyrolytic effects induced by energetic ions in polymers

    Science.gov (United States)

    Steckenreiter, T.; Balanzat, E.; Fuess, H.; Trautmann, C.

    1999-05-01

    Degradation processes in various polymers (polycarbonate, poly(ethyleneterephthalate), polyimide, and polysulfone) induced by krypton and molybdenum ions of several hundred MeV were studied by infrared and mass spectroscopy. A wide spectrum of degradation products well known from low ionizing radiation were found, which are strongly enhanced if the irradiation takes place in oxygen atmosphere. Most notables are the formation of triple bonded species such as alkynes, cyanates and acetylene. They are created within a radius of about 3-4 nm around the ion trajectory. The complementing observation of degradation products in the bulk polymer and as volatile fragments allows a detailed description of the underlying decomposition mechanisms. The observation of degradation products in close analogy to pyrolysis and the thermal stability of acetylene, strongly suggest that transient temperatures above 1500 K are involved in the track formation process.

  11. Experimental study of effect of stenosis geometry on flow parameters

    Directory of Open Access Journals (Sweden)

    Veselý Ondřej

    2015-01-01

    Full Text Available A stenosis is a narrowing in a tubular organ or structure. In medicine, vessel stenosis poses health risks for people. In this work, experimental investigations of pressure loss coefficient for varying stenosis eccentricity and shape were performed. Five models of different geometry were studied; all models were stenosis of 75 % area reduction. The flow conditions approximate physiological flow. The measuring range of Reynolds number was from 130 to 2730, measured values of pressure loss coefficient were from 12 to 20. The steady experimental results indicated that static pressure loss coefficient is affected by the shape of stenosis, but it was affected more significantly by the eccentricity. Visualization experiments have been performed in Polycarbonate models.

  12. Side Effects

    Science.gov (United States)

    Side effects are problems that occur when cancer treatment affects healthy tissues or organs. Learn about side effects caused by cancer treatment. Know what signs and symptoms to call your doctor about. Learn about treatments for side effects.

  13. Human urinary excretion of non-persistent environmental chemicals

    DEFF Research Database (Denmark)

    Frederiksen, Hanne; Jensen, Tina Kold; Jørgensen, Niels

    2014-01-01

    ), triclosan (TCS), and parabens because of their anti-androgenic and/or estrogenic effects. Phthalates are plasticizers used in numerous industrial products. Bisphenol A is the main component of polycarbonate plastics and epoxy resins. Parabens and TCS are antimicrobial preservatives and other phenols...

  14. Influence of flavour absorption on oxygen permentation through LDPE, PP, PC and PET plastics food packaging

    NARCIS (Netherlands)

    Willige, van R.W.G.; Linssen, J.P.H.; Meinders, M.B.J.; Stege, van der H.J.; Voragen, A.G.J.

    2002-01-01

    The effect of flavour absorption on the oxygen permeability of low-density polyethylene (LDPE), polypropylene (PP), polycarbonate (PC) and polyethylene terephthalate (PET) was studied using an isostatic continuous flow system. Polymer samples were exposed to a model solution containing limonene,

  15. Natural fabric of Hildegardia populifolia composites

    CSIR Research Space (South Africa)

    Guduri, BBR

    2006-12-01

    Full Text Available -polycarbonate toughened epoxy composites was investigated using Instron and scanning electron microscope (SEM). It was found that the presence of NaOH and silane coupling agent treatment has an effect on the mechanical properties of composites. In the presence of surface...

  16. 78 FR 48766 - Petition for Waiver of Compliance

    Science.gov (United States)

    2013-08-09

    ... rural areas at speeds up to 30 mph. The glazing in these coaches is polycarbonate plastic and meets the... purchased by the parent company of IAIS, Railroad Development Corporation, in autumn 2006 for excursion... will remain in effect. A copy of the petition, as well as any written communications concerning the...

  17. Proton induced modification in makrofol-DE

    Indian Academy of Sciences (India)

    Unknown

    Irradiation effects of a 3 MeV proton beam on polycarbonate (makrofol-DE (MFD)) have been studied with respect to its electrical, thermal and structural behaviour by using an LCR meter, DSC/TGA and. FTIR spectroscopy. The dielectric ... ing and degradation take place during proton irradiation and are closely related to ...

  18. Chemical nanotechnology talks IV (CNT4): Emerging applications in electronics, optoelectronics, energy and sensors. Book of abstracts

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    Characterization of nanoparticles, nanocrystals, liquid crystals and semiconductive, conductive and conjugated polymers (PAA, polycarbonates, PANI, sulfonated PS, polyphenylenevinylene, polythiophen). Applications of this polymers, blends and nanocomposites with this polymers in electronics (capacitors, field effect transistors, batteries) and optoelectronics (LEDs, solar cells).

  19. Stress-Induced Crystallization of Ge-Doped Sb Phase-Change Thin Films

    NARCIS (Netherlands)

    Eising, Gert; Pauza, Andrew; Kooi, Bart J.

    The large effects of moderate stresses on the crystal growth rate in Ge-doped Sb phase-change thin films are demonstrated using direct optical imaging. For Ge6Sb94 and Ge7Sb93 phase-change films, a large increase in crystallization temperature is found when using a polycarbonate substrate instead of

  20. Systems effectiveness

    CERN Document Server

    Habayeb, A R

    1987-01-01

    Highlights three principal applications of system effectiveness: hardware system evaluation, organizational development and evaluation, and conflict analysis. The text emphasizes the commonality of the system effectiveness discipline. The first part of the work presents a framework for system effectiveness, partitioning and hierarchy of hardware systems. The second part covers the structure, hierarchy, states, functions and activities of organizations. Contains an extended Appendix on mathematical concepts and also several project suggestions.

  1. Membrane extraction with sorbent interface-gas chromatography as an effective and fast means for continuous monitoring of thermal degradation products of polyacrylonitrile.

    Science.gov (United States)

    Kaykhaii, Massoud; Sarafraz-Yazdi, Ali; Chamsaz, Mahmood; Pawliszyn, Janusz

    2002-07-01

    A novel sample preparation technique, membrane extraction with a sorbent interface (MESI) has been optimized and used for continuous monitoring thermal degradation products in polyacrylonitrile (PAN) polymer headspace at different temperatures, followed by gas chromatography-mass spectrometry (GC-MS). MESI with a flat sheet poly(dimethyl siloxane)-polycarbonate (PDMS-PC) membrane and Tenax trap was used. The system is very simple, fast and reliable and allowed us to extract, enrich and continuously monitor major volatile compounds released from the polymer at different temperatures. The volatile and semi-volatile gaseous degradation products were identified. Sensitivity of the method depends on the length of time for trapping.

  2. "Further Effects"

    Science.gov (United States)

    Kinigstein, Steven Michael

    In writing Further Effects, I intended to illustrate the benefits that are to be had from the use of effects - processing, when applied at the compositional level, rather than as a post-compositional afterthought. When effects are used creatively in the compositional stage, they will influence the very nature of a piece. They are capable of expressing rhythmic and metric ideas. They can alter the natural timbre of an instrument. This can be done on levels of abstraction ranging from discreet subtlety to disguise beyond recognition. There is one effect (known as "pitch shift.") that allows an instrument to play pitches that are well outside of its range. In Further Effects, I direct the performers to use a volume pedal (which I view as a tool, rather than an effect) for the broadened creative use of dynamics that it so efficiently grants. The use of an effects processor and volume pedal creates a need for ancillary equipment. An amplifier, cables, and an electric hook-up (a microphone or a pickup) will be required for each instrument. While an amplifier serves to project the processed sound, there must also be a device or method to suppress unprocessed sound. A great deal of thought and work goes into the use of effects; yet I feel it is wasteful to use this musical resource merely as post-compositional decoration.

  3. Thermal Effects.

    Science.gov (United States)

    Talmage, Sylvia S.; Coutant, Charles C.

    1978-01-01

    Presents a literature review of the effect of temperature on the biosphere water, covering publications of 1976-77. This review includes the effects of temperature on growth, production, and embryonic and larval development. A list of 401 references is also presented. (HM)

  4. Experimental study of the simulated process of degradation of polycarbonate- and D,L-lactide-based polyurethane elastomers under conditions mimicking the physiological environment

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Serkis, Magdalena; Poreba, Rafal; Machová, Luďka; Hodan, Jiří; Kredatusová, Jana; Kubies, Dana; Zhigunov, Alexander

    2016-01-01

    Roč. 125, March (2016), s. 115-128 ISSN 0141-3910 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : polyurethane * elastomer * hydrolytic degradation Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.386, year: 2016

  5. Improvement of mechanical strength and osteogenic potential of calcium sulfate-based hydroxyapatite 3-dimensional printed scaffolds by ε-polycarbonate coating.

    Science.gov (United States)

    Kim, Beom-Su; Yang, Sun-Sik; Park, Ho; Lee, Se-Hwan; Cho, Young-Sam; Lee, Jun

    2017-09-01

    Powder-based three-dimensional (3D) printing is an excellent method to fabricate complex-shaped scaffolds for tissue engineering. However, their lower mechanical strength restricts their application in bone tissue engineering. Here, we created a 3D-printed scaffold coated with a ε-polycaprolactone (PCL) polymer solution (5 and 10 w/v %) to improve the mechanical strength of the scaffold. The 3D scaffold was fabricated from calcium sulfate hemihydrate powder (CaSO 4 -1/2 H 2 O), transformed into hydroxyapatite (HAp) by treatment with a hydrothermal reaction in an NH 4 H 2 PO 4 solution. The surface properties and composition of the scaffold were evaluated using scanning electron microscopy and X-ray diffraction analysis. We demonstrated that the 3D scaffold coated with PCL had an improved mechanical modulus. Coating with 5 and 10% PCL increased the compressive strength significantly, by about 2-fold and 4-fold, respectively, compared with that of uncoated scaffolds. However, the porosity was reduced significantly by coating with 10% PCL. In vitro biological evaluation demonstrated that MG-63 cells adhered well and proliferated on the 3D scaffold coated with PCL, and the scaffold was not cytotoxic. In addition, alkaline phosphatase activity and real time polymerase chain reaction demonstrated that osteoblast differentiation also improved in the PCL-coated 3D scaffolds. These results indicated that PCL polymer coating could improve the compressive strength and biocompatibility of 3D HAp scaffolds for bone tissue engineering applications.

  6. Placebo Effect

    Science.gov (United States)

    ... the placebo. Some people wonder whether it is fair or ethical to give a placebo treatment to ... carefully done using a placebo, so that the true effect of the treatment can be fully understood. ...

  7. Effective Parenting

    Science.gov (United States)

    ... Listen Español Text Size Email Print Share Effective Parenting Page Content Article Body Now that our children ... school play and his soccer games. Your Current Parenting Experiences Spend some time thinking about how you ...

  8. Biological effects

    International Nuclear Information System (INIS)

    Trott, K.R.

    1973-01-01

    Following an introduction into the field of cellular radiation effect considering the most important experimental results, the biological significance of the colony formation ability is brought out. The inactivation concept of stem cells does not only prove to be good, according to the present results, in the interpretation of the pathogenesis of acute radiation effects on moult tissue, it also enables chronicle radiation injuries to be interpreted through changes in the fibrous part of the organs. Radiation therapy of tumours can also be explained to a large extent by the radiation effect on the unlimited reproductiveness of tumour cells. The more or less similar dose effect curves for healthy and tumour tissue in practice lead to intermittent irradiation. The dependence of the intermittent doses and intervals on factors such as Elkind recovery, synchronisation, redistribution, reoxygenation, repopulation and regeneration are reviewed. (ORU/LH) [de

  9. Facebook Effect

    OpenAIRE

    STOICA, Anamaria

    2011-01-01

    This research paper is intended to understand the effects that Facebook, the social networking site has upon us, whether it influences our lives in a good or in a bad way. In order to understand the Facebook Effect we are trying to see how it impacts our lives at economic level,social level, political level, terminology level , psychological level and cultural level . Starting from the question : What does Facebook want? we found several answers consisting in pros and cons of this phenomenon ...

  10. Effective Programming

    DEFF Research Database (Denmark)

    Frost, Jacob

    To investigate the use of VTLoE as a basis for formal derivation of functional programs with effects. As a part of the process, a number of issues central to effective formal programming are considered. In particular it is considered how to develop a proof system suitable for pratical reasoning......, how to implement this system in the generic proof assistant Isabelle and finally how to apply the logic and the implementation to programming....

  11. Study on dosimetry characteristics of polymer–CNT nanocomposites: Effect of polymer matrix

    Energy Technology Data Exchange (ETDEWEB)

    Malekie, Shahryar [Radiation Application Research School, Nuclear Science & Technology Research Institute, PO Box 11365-3486, Tehran (Iran, Islamic Republic of); Ziaie, Farhood, E-mail: fziaie@aeoi.org.ir [Radiation Application Research School, Nuclear Science & Technology Research Institute, PO Box 11365-3486, Tehran (Iran, Islamic Republic of); Esmaeli, Abdolreza [Plasma and Fusion Research School, Nuclear Science & Technology Research Institute, Tehran (Iran, Islamic Republic of)

    2016-04-21

    In this research work, the current density of polymer–carbon nanotube nanocomposite in different weight percentages of nanotubes, over the radiation absorbed dose under a fixed DC voltage for different polymer matrices such as high density polyethylene, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, and polystyrene was investigated via finite element method. The predicted electrical percolation threshold values in different composites were validated by experimental results published by other scientists. The absorbed dose value was considered as multiplying of heat capacity and temperature rise of the composite, regarding the calorimetric approach. Results show that the polymer type having different characteristics of relative permittivity and heat capacity could affect the sensitivity and working dose range of the composite as a dosimeter.

  12. The effect of thermal damage on the mechanical properties of polymer regrinds

    Science.gov (United States)

    Kundu, Nikhil K.

    1990-01-01

    Reprocessed polymers are subjected to high processing temperatures that result in the breakdown of molecular chains and changes in the molecular structures. These phenomena are reflected in the mechanical properties of materials. Practically every regrind is seen as a new material. These experiments deal with the molding, regrinding, and reprocessing of test specimens for the study of their mechanical properties. The comparative test data from each recycled material would give students an insight of the molecular structures and property degradation. Three important rheological and mechanical properties such as melt flow, impact strength, and flexural strength are to be determined. These properties play key roles in the selection of engineering materials. The material selected for demonstration was Makrolon 3000L, a polycarbonate thermoplastic from Bayer AG. The thermal degradation due to repeated processing is reflected in the decrease in molecular weight and breakdown of molecular chains causing increase in melt flow. The Izod-impact resistance and the flexural strength deteriorate gradually.

  13. The Effect of the Choice of Experimental Data on Polymer Blend Predictions

    Science.gov (United States)

    Tambasco, Michael; Lipson, Jane

    2004-03-01

    Different kinds of experimental data may be used to characterize polymer blends; given that only a limited amount of data are likely to be collected, what characteristic measurements would be of greatest value? Each type of data provides its own description of the system, therefore understanding the correlations and consistency between the thermodynamic 'pictures' resulting from the different experiments will be essential in determing the optimal data set for a polymer blend. We will focus on two blends, polystyrene/poly(vinyl methyl ether) (PS/PVME) and polystyrene/tetra-methyl bisphenol-A polycarbonate (PS/TMPC), and will exploit the wide variety of data available on each, including: pressure-volume-temperature (PVT) data for pure fluids and mixtures, coexistence curves, and neutron scattering intensities. Differences in the choice of data analyzed on the predictions of polymer blend properties will be discussed, as will thoughts regarding the optimal data set for the characterization of polymer blends at equilibrium.

  14. Effect of spatially correlated generation of macroradicals in the radiolysis of polymers

    International Nuclear Information System (INIS)

    Bol'bit, N.M.; Taraban, V.B.; Klinshpont, Eh.R.; Shelukhov, I.P.; Milinchuk, V.K.

    2000-01-01

    Multiple increase in radiation-chemical yield of macro radicals when polymers (polystyrene, polymethylmethacrylate, polycarbonate) are subjected to ionizing radiations at super-low absorbed dose rates (0.1-1 mGy/s) in vacuum at room temperature was revealed. A model of radiolysis process was suggested based on the mechanism of preferable generation and stabilization of macro radicals during polymer irradiation in the vicinity of macro radicals available at the moment. The mechanism results in formation of clusters (swarms) of free radicals. Experiments of luminescence quenching permitted ascertaining the efficiency of spatially correlated generation of macro radicals, degree of clustering and average ratio of the clusters in certain polymers and scintillators on their basis [ru

  15. Study on dosimetry characteristics of polymer–CNT nanocomposites: Effect of polymer matrix

    International Nuclear Information System (INIS)

    Malekie, Shahryar; Ziaie, Farhood; Esmaeli, Abdolreza

    2016-01-01

    In this research work, the current density of polymer–carbon nanotube nanocomposite in different weight percentages of nanotubes, over the radiation absorbed dose under a fixed DC voltage for different polymer matrices such as high density polyethylene, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, and polystyrene was investigated via finite element method. The predicted electrical percolation threshold values in different composites were validated by experimental results published by other scientists. The absorbed dose value was considered as multiplying of heat capacity and temperature rise of the composite, regarding the calorimetric approach. Results show that the polymer type having different characteristics of relative permittivity and heat capacity could affect the sensitivity and working dose range of the composite as a dosimeter.

  16. Effect of Linkage Groups on Motional Cooperativity in Secondary Relaxations of Some Glassy Polymers

    Science.gov (United States)

    Li, Lei; Yee, Albert F.

    2000-03-01

    In our previous research we found that the secondary relaxation of bisphenol-A (BPA) polycarbonate is due to a cooperative motion which includes several repeat units. Clearly the linkage between neighboring BPA segments must play an important role. It is expected that a more flexible linkage would require less motional cooperativity. To demonstrate this idea, polyformals based on the comonomers BPA, tetramethyl-BPA and methylenechloride with controlled sequence structure were synthesized and DMA studies were conducted. The results show that the secondary relaxation behavior of copolyformals is not dependent on the block length of BPA segments, which suggest that the molecular motion does not require in-chain cooperation. The lower in-chain motional cooperativity of BPA-polyformal is attributed to the lower rotational energy barrier of the formal linkage.

  17. Effect of culture conditions on the resistance of Pseudomonas aeruginosa biofilms to disinfecting agents.

    Science.gov (United States)

    Abdallah, Marwan; Benoliel, Corinne; Ferreira-Theret, Pauline; Drider, Djamel; Dhulster, Pascal; Chihib, Nour-Eddine

    2015-01-01

    The relationship between the environmental conditions of biofilm formation and resistance to disinfectants was studied. Anti-biofilm assays were performed against biofilms grown at 20, 30 and 37°C on stainless steel and polycarbonate, over 24 and 48 h. A rise in growth temperature increased the resistance of 24 h biofilms to disinfectants containing didecyldimethylammonium chloride and decreased it to a disinfectant containing alkyldimethylbenzylammonium chloride. The increase in growth temperature coupled with an incubation time of 24 h promoted increases in both matrix production and the membrane rigidity of sessile cells. An increase in incubation time also increased both matrix production and the membrane rigidity of sessile cells. Such phenomena resulted in an increased resistance to disinfectants of biofilms grown at 20 and 30°C. The resistance of 48 h biofilms to disinfectants decreased with an increase in growth temperature despite the increase in matrix production and the membrane rigidity of sessile cells.

  18. Effects of Graphene Monolayer Coating on the Optical Performance of Remote Phosphors

    Science.gov (United States)

    Yazdan Mehr, M.; Volgbert, S.; van Driel, W. D.; Zhang, G. Q.

    2017-10-01

    A graphene monolayer has been successfully coated on one side of a bisphenol-A-polycarbonate (BPA-PC) plate, used as a substrate for remote phosphor applications in light-emitting diode (LED)-based products. Using a photoresist transferring method, graphene sheet has been coated on BPA-PC plates. The results show that this graphene monolayer significantly improves the lifetime and performance of LEDs mainly by protecting them against external degradation factors such as moisture and oxygen. Also, LED-based products composed of graphene-coated BPA-PC plates exhibit longer stability with comparatively less loss of luminous efficiency. This method has great potential to significantly improve the reliability of not only LED-based products but also many other microelectronics packaging and components, in which moisture and oxygen are the key causes of failures.

  19. Genetic effects

    International Nuclear Information System (INIS)

    Kato, Hiroo

    1975-01-01

    In 1948-1953 a large scale field survey was conducted to investigate the possible genetic effects of A-bomb radiation on over 70,000 pregnancy terminations in the cities of Hiroshima and Nagasaki. The indices of possible genetic effect including sex ratio, birth weight, frequency of malformation, stillbirth, neonatal death, deaths within 9 months and anthropometric measurements at 9 months of age for these children were investigated in relation to their parent's exposure status to the A-bomb. There were no detectable genetic effects in this sample, except for a slight change in sex ratio which was in the direction to be expected if exposure had induced sex-linked lethal mutations. However, continued study of the sex ratio, based upon birth certificates in Hiroshima and Nagasaki for 1954-1962, did not confirm the earlier trend. Mortality in these children of A-bomb survivors is being followed using a cohort of 54,000 subjects. No clearly significant effect of parental exposure on survival of the children has been demonstrated up to 1972 (age 17 on the average). On the basis of the regression data, the minimal genetic doubling dose of this type of radiation for mutations resulting in death is estimated at 46 rem for the father and 125 rem for the mother. (auth.)

  20. Treatment Effects

    DEFF Research Database (Denmark)

    Heckman, James J.; Lopes, Hedibert F.; Piatek, Rémi

    2014-01-01

    This paper contributes to the emerging Bayesian literature on treatment effects. It derives treatment parameters in the framework of a potential outcomes model with a treatment choice equation, where the correlation between the unobservable components of the model is driven by a low-dimensional v...... easily be applied....

  1. Ventilation Effectiveness

    DEFF Research Database (Denmark)

    Mundt, M.; Mathisen, H. M.; Moser, M.

    Improving the ventilation effectiveness allows the indoor air quality to be significantly enhanced without the need for higher air changes in the building, thereby avoiding the higher costs and energy consumption associated with increasing the ventilation rates. This Guidebook provides easy-to-un...

  2. Effects of Water Bottle Materials and Filtration on Bisphenol A Content in Laboratory Animal Drinking Water.

    Science.gov (United States)

    Honeycutt, Jennifer A; Nguyen, Jenny Q T; Kentner, Amanda C; Brenhouse, Heather C

    2017-05-01

    Bisphenol A (BPA) is widely used in the polycarbonate plastics and epoxy resins that are found in laboratory animal husbandry materials including cages and water bottles. Concerns about BPA exposure in humans has led to investigations that suggest physiologic health risks including disruptions to the endocrine system and CNS. However, the extent of exposure of laboratory animals to BPA in drinking water is unclear. In the first study, we compared the amount of BPA contamination in water stored in plastic bottles used in research settings with that in glass bottles. The amount of BPA that leached into water was measured across several time points ranging from 24 to 96 h by using a BPA ELISA assay. The results showed that considerable amounts of BPA (approximately 0.15 μg/L) leached from polycarbonate bottles within the first 24 h of storage. In the second study, BPA levels were measured directly from water taken from filtered compared with unfiltered taps. We observed significantly higher BPA levels in water from unfiltered taps (approximately 0.40 μg/L) compared with taps with filtration systems (approximately 0.04 μg/L). Taken together, our findings indicate that the use of different types of water bottles and water sources, combined with the use of different laboratory products (food, caging systems) between laboratories, likely contribute to decreased rigor and reproducibility in research. We suggest that researchers consider reporting the types of water bottles used and that animal care facilities educate staff regarding the importance of flushing nonfiltered water taps when filling animal water bottles.

  3. Adsorption of polypropylene oxide-polyethylene oxide type surfactants at surfaces of pharmaceutical relevant materials: effect of surface energetics and surfactant structures.

    Science.gov (United States)

    Li, Jinjiang; Rudraraju, Sneha; Zheng, Songyan; Jaiswal, Archana

    2018-01-18

    Protein therapeutics are exposed to various surfaces during product development, where their adsorption possibly causes unfolding, denaturation, and aggregation. In this paper, we aim to characterize four types of typical surfaces used in the development of biologics: polycarbonate, polyethersulfone, borosilicate glass, and cellulose. Contact angles of these surfaces were measured using three probing liquids: water, formamide, and diidomethane, from which acid/base (AB) and Lifshitz-van der Waals (LW) interaction components were derived. To explore the interactions of surfactants of Pluronics/Poloxamers (PEO-PPO-PEO copolymers) with these surfaces, the adsorption of three Pluronics (F68, F127, and L44) at these surfaces was determined using a quartz crystal microbalance with dissipation technique (QCM-D). For hydrophobic surfaces without AB component (polycarbonate and polyethersulfone), these copolymers exhibited significant adsorption with a little dissipation at low concentrations. For hydrophilic surfaces with AB component (cellulose and borosilicate), the adsorption at low-surfactant concentration is low while dissipation is relatively high. Additionally, the chemical properties of Pluronics such as the ratio of PPO to PEO, along with the interaction of PPO with surfaces were observed to play a critical role in adsorption. Furthermore, the interfacial structure of the adsorbed layer was affected by both AB interaction and the presence of PEO block.

  4. Health effects

    International Nuclear Information System (INIS)

    Mahieu, L.

    1998-01-01

    The main objectives of research in the field of health effects at the Belgian Nuclear Research Centre SCK-CEN are: (1) to study cancer mortality and morbidity in nuclear workers in Belgium; (2) to document the feasibility of retrospective cohort studies in Belgium; (3) to participate in the IARC study; (4) to elucidate the mechanisms of the effects of ionizing radiation on the mammalian embryo during the early phases of its development; (5) to assess the genetic risks of material exposure to ionizing radiation; (6) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (7) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas for 1997 are reported

  5. Health effects

    Energy Technology Data Exchange (ETDEWEB)

    Mahieu, L

    1998-07-01

    The main objectives of research in the field of health effects at the Belgian Nuclear Research Centre SCK-CEN are: (1) to study cancer mortality and morbidity in nuclear workers in Belgium; (2) to document the feasibility of retrospective cohort studies in Belgium; (3) to participate in the IARC study; (4) to elucidate the mechanisms of the effects of ionizing radiation on the mammalian embryo during the early phases of its development; (5) to assess the genetic risks of material exposure to ionizing radiation; (6) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (7) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas for 1997 are reported.

  6. Effective Teachers

    Directory of Open Access Journals (Sweden)

    Beverly A. King Miller

    2015-09-01

    Full Text Available This article focuses on the educational strategies that can be used to support female students of African descent in their persistence in science, technology, engineering, and mathematics (STEM education and careers. STEM careers have historically been White male and White female dominated, which has yielded an underrepresentation of those of African descent. Drawing from a grounded qualitative case study, the data used for this article share the responses of Afro-Caribbean females in STEM who have immigrated to the United States from the country of Panama. As Latinas, they are representative of the changing face in the American educational system—bilingual, multicultural, and of African descent. The strategies offered reflect their own teaching practices, their former teachers, or experiences with their children’s teachers. What emerged were descriptions of four strategies and behaviors of effective teachers that align with Ladson-Billings’s culturally relevant pedagogy and Gay’s culturally responsive teaching. Included in the findings are the high standards and expectations embodied by effective teachers that serve to positively inspire their students. Culturally responsive teachers create an atmosphere of learning that supports academic success, conveying their belief in their students’ ability based upon their own reflectivity. As the U.S. educational system continues to become multilingual and multicultural, there is need for strategies for the successful inclusion and progression of students in STEM educational pathways and careers. This will occur as teachers challenge themselves to be the agents of change in the lives of their students.

  7. Effective Protection or Effective Combat

    DEFF Research Database (Denmark)

    Lemberg-Pedersen, Martin

    2016-01-01

    and multilocal character of European border control. This is then elaborated via a critical gaze at several attempts to defi ne how European states have attempted to externalize migration control to other countries in terms of supranational policy drives, ripple and mimicry effects. This then facilitates a more...... nuanced understanding of externalization. Since border control reterritorializes geographic spaces according to the mobility of the people through them, it follows that the EU’s border control, and with it also aspects of the union’s asylum policy, have both biopolitical and geopolitical implications...

  8. Condom effectiveness.

    Science.gov (United States)

    Porche, D J

    1998-01-01

    People who choose not to abstain from sexual intercourse can use barrier contraceptive methods, such as condoms, to reduce their risk of contracting HIV and other sexually transmitted diseases (STDs). Health care providers who provide safer sex education and counseling should provide information on condoms as a way of reducing the risk of HIV/STD transmission. Since latex condoms are regulated by the US Food and Drug Administration (FDA) as medical devices, FDA regulations govern latex condom manufacturing and testing in accordance with stringent national standards. The FDA randomly tests imported condoms according to the same stringent quality control standards as US-produced condoms. Condom effectiveness, however, depends upon their correct and consistent use during every sexual act. Relevant data and guidelines are presented on the correct use of male latex and female polyurethane condoms. Both male latex and female polyurethane condoms can prevent the transmission of HIV and other STDs.

  9. Radiation effects

    International Nuclear Information System (INIS)

    Collings, E.W.

    1986-01-01

    An important cause of deterioration in superconducting magnets intended for high-energy physics and fusion-reactor applications is radiation damage. The present chapter deals chiefly with the effects of electron, proton, gamma and neutron irradiation on the properties of stabilized Ti-Nb-base composite superconductors. The authors examine the particle-accelerator environment, electron irradiation of Ti-Nb superconductor, proton irradiation of Ti-Nb superconductor and its stabilizer, and deuteron irradiation of Ti-Nb superconductor. A section discussing the fusion reactor environment in general is presented, and the two principal classes of fusion reactor based on the magnetic-confinement concept, namely the tokamak and the mirrormachine are examined. Also discussed is neutron irradiation of Cu/TiNb composite superconductors and critical current density of neutronirradiated Ti-Nb. Finally, radiation damage to stabilizer and insulating materials is described

  10. Health effects

    International Nuclear Information System (INIS)

    Mahieu, L.

    1998-01-01

    The objectives of the research in the field of epidemiology , performed at the Belgian Nuclear Research Centre SCK-CEN are (1) to study cancer mortality and morbidity in nuclear workers in Belgium; (2) to document the feasibility of retrospective cohort studies in Belgium; (3) to participate in the IARC study. For radiobiology, the main objectives are: (1) to elucidate the mechanisms of the effects of ionizing radiation on the mammalian embryo during the early phase of its development, (2) to assess the genetic risks of maternal exposure to ionizing radiation, (3) to elucidate the mechanisms by which damage to the brain and mental retardation are caused in man after prenatal irradiation. The main achievements in these domains for 1997 are presented

  11. Effect of Crystallographic Texture on Magnetic Characteristics of Cobalt Nanowires

    Directory of Open Access Journals (Sweden)

    Usman M

    2010-01-01

    Full Text Available Abstract Cobalt nanowires with controlled diameters have been synthesized using electrochemical deposition in etched ion-track polycarbonate membranes. Structural characterization of these nanowires with diameter 70, 90, 120 nm and length 30 μm was performed by scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction techniques. The as-prepared wires show uniform diameter along the whole length and X-ray diffraction analysis reveals that [002] texture of these wires become more pronounced as diameter is reduced. Magnetic characterization of the nanowires shows a clear difference of squareness and coercivity between parallel and perpendicular orientations of the wires with respect to the applied field direction. In case of parallel applied field, the coercivity has been found to be decreasing with increasing diameter of the wires while in perpendicular case; the coercivity observes lower values for larger diameter. The results are explained by taking into account the magnetocrystalline and shape anisotropies with respect to the applied field and domain transformation mechanism when single domain limit is surpassed.

  12. Effect of Crystallographic Texture on Magnetic Characteristics of Cobalt Nanowires

    Science.gov (United States)

    Maaz, K.; Karim, S.; Usman, M.; Mumtaz, A.; Liu, J.; Duan, J. L.; Maqbool, M.

    2010-07-01

    Cobalt nanowires with controlled diameters have been synthesized using electrochemical deposition in etched ion-track polycarbonate membranes. Structural characterization of these nanowires with diameter 70, 90, 120 nm and length 30 μm was performed by scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction techniques. The as-prepared wires show uniform diameter along the whole length and X-ray diffraction analysis reveals that [002] texture of these wires become more pronounced as diameter is reduced. Magnetic characterization of the nanowires shows a clear difference of squareness and coercivity between parallel and perpendicular orientations of the wires with respect to the applied field direction. In case of parallel applied field, the coercivity has been found to be decreasing with increasing diameter of the wires while in perpendicular case; the coercivity observes lower values for larger diameter. The results are explained by taking into account the magnetocrystalline and shape anisotropies with respect to the applied field and domain transformation mechanism when single domain limit is surpassed.

  13. PHOTOCATALYTIC EFFECT OBTAINED ON TEXTILE BY FINISHING TECHNIQUES

    Directory of Open Access Journals (Sweden)

    POPESCU Alina

    2017-05-01

    Full Text Available This study approached the experimentation of deposition by padding of commercial photocatalytic dispersion AERODISP® W 740 X with 40% solid content of TiO2 on RIPSTOP fabric, made of 100% cotton yarns Nm 70/1 and a network of polyester filament yarns 330 dtex, both in warp and weft directions. The deposition of photocatalytic dispersions on the textile material have been realised by treatment in concomitent phase of textile support with photocatalytic dispersions and with chemical substances used in fixation of TiO2 nanoparticles. As chemical substances used in fixation of TiO2 nanoparticles different crosslinking agents have been used: Itobinder AG (acrylic copolymer, Itobinder U30 NEW (polycarbonate urethane polymer and Itocoat LJ25 (urethane resin. Itocatalyst SCS and Itocatalyst A were used as catalysts. Photocatalytic activity of functionalized textile materials was evaluated by determining the photodegradation efficiency of methylene blue dye as pollutant, measuring the color difference of the irradiated samples compared with non-irradiated samples. Washing durability of the samples treated with photocatalytic dispersions was conducted qualitatively by determining the photocatalytic activity remaining on the textile fabrics after 1 washing cycle. Electron microscopy was used for viewing the distribution of TiO2 particles on the surface of textile materials treated with the photocatalytic dispersions. Ti content existing on the surface of the textile materials was performed by energy dispersive X-ray spectroscopy.

  14. Thyroid effects

    International Nuclear Information System (INIS)

    Maxon, H.; Thomas, S.; Buncher, C.; Book, S.; Hertzberg, V.

    1985-01-01

    Risk coefficients for thyroid disorders have been developed for both 131 I and external x or gamma low-LET radiation. A linear, no-threshold model has been used for thyroid neoplasms. A linear, threshold model has been used for other thyroid disorders. Improvements since the Reactor Safety Study were made possible by relevant new animal and human data. Major changes are as follows. Animal data are used to supplement the human experience where necessary. A specific risk estimate model is used for thyroid neoplasms, which accounts for observed effects of gender and age at exposure on risk. For thyroid cancer, the basis of the risk coefficients is the experience of North Americans following x-irradiation for benign disease in childhood. This recognizes possible differences in susceptibility in people of different heritage. A minimum induction period for thyroid neoplasms following irradiation is used to define periods at risk. An upper bound risk coefficient for cancer induction following exposure to 131 I is based on human experience at relatively low dose exposures. While the overall lifetime risks of death due to thyroid cancer are consistent with projections by the ICRP, BEIR III, and UNSCEAR Reports, the current model permits greater flexibility in determining risk for population subgroups. 88 references, 8 tables

  15. A study of the static to kinetic friction transition of polymers

    OpenAIRE

    Lee, Edward Chungjen

    1995-01-01

    This study investigates the transition from static to kinetic friction for structural polymers and continues previous research conducted by Dr. N. S. Eiss, B. McCann, and R. Molique. A new test apparatus which simultaneously measures friction, normal load, and relative velocity was developed to study this transition. The polymers used in this study were nylon, ABS, polycarbonate, and fiberglass filled and unfilled polypropylene. Creep effects of polymers on the static coefficie...

  16. Bisphenol A: Perinatal exposure and body weight

    OpenAIRE

    Rubin, Beverly S.; Soto, Ana M.

    2009-01-01

    Bisphenol A (BPA) is a component of polycarbonate and other plastics including resins that line food and beverage containers. BPA is known to leach from products in contact with food and drink, and is therefore thought to be routinely ingested. In a recent cross sectional study, BPA was detected in urine samples from 92.6% of the US population examined. The potential for BPA to influence body weight is suggested by in vitro studies demonstrating effects of BPA on adipocyte differentiation, li...

  17. Effects of Anesthesia

    Science.gov (United States)

    ... Media ASA Member Toolkit Anesthesia 101 Effects of Anesthesia Explore this page: Effects of Anesthesia How can ... of anesthesia and their side effects? Effects of Anesthesia If you’re having surgery, you most likely ...

  18. Colossal magnetodielectric effect caused by magnetoelectric effect ...

    Indian Academy of Sciences (India)

    The colossal magnetodielectric effect is reported in Pb(Zr,Ti)O3/Terfenol-D laminate composite under low magnetic field. When the composite is placed in an external a.c. magnetic field, magnetoelectric effect is produced, as a result, the dielectric properties of the Pb(Zr,Ti)O3 is changed, i.e. magnetodielectric effect. Both the ...

  19. Computational and experimental study of nanoporous membranes for water desalination and decontamination.

    Energy Technology Data Exchange (ETDEWEB)

    Hickner, Michael A. (Penn State University, University Park, PA); Chinn, Douglas Alan (Sandia National Laboratories, Albuquerque, NM); Adalsteinsson, Helgi; Long, Kevin R. (Texas Tech University, Lubbock, TX); Kent, Michael Stuart (Sandia National Laboratories, Albuquerque, NM); Debusschere, Bert J.; Zendejas, Frank J.; Tran, Huu M.; Najm, Habib N.; Simmons, Blake Alexander

    2008-11-01

    Fundamentals of ion transport in nanopores were studied through a joint experimental and computational effort. The study evaluated both nanoporous polymer membranes and track-etched nanoporous polycarbonate membranes. The track-etched membranes provide a geometrically well characterized platform, while the polymer membranes are more closely related to ion exchange systems currently deployed in RO and ED applications. The experimental effort explored transport properties of the different membrane materials. Poly(aniline) membranes showed that flux could be controlled by templating with molecules of defined size. Track-etched polycarbonate membranes were modified using oxygen plasma treatments, UV-ozone exposure, and UV-ozone with thermal grafting, providing an avenue to functionalized membranes, increased wettability, and improved surface characteristic lifetimes. The modeling effort resulted in a novel multiphysics multiscale simulation model for field-driven transport in nanopores. This model was applied to a parametric study of the effects of pore charge and field strength on ion transport and charge exclusion in a nanopore representative of a track-etched polycarbonate membrane. The goal of this research was to uncover the factors that control the flux of ions through a nanoporous material and to develop tools and capabilities for further studies. Continuation studies will build toward more specific applications, such as polymers with attached sulfonate groups, and complex modeling methods and geometries.

  20. Synthesis of titanium oxide nanoparticles using DNA-complex as template for solution-processable hybrid dielectric composites

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, J.C. [Center for Sustainable Materials Chemistry, 153 Gilbert Hall, Oregon State University, Corvallis, OR (United States); Mejia, I.; Murphy, J.; Quevedo, M. [Department of Materials Science and Engineering, University of Texas at Dallas, Dallas, TX (United States); Garcia, P.; Martinez, C.A. [Engineering and Technology Institute, Autonomous University of Ciudad Juarez, Ciudad Juarez, Chihuahua (Mexico)

    2015-09-15

    Highlights: • We developed a synthesis method to produce TiO{sub 2} nanoparticles using a DNA complex. • The nanoparticles were anatase phase (~6 nm diameter), and stable in alcohols. • Composites showed a k of 13.4, 4.6 times larger than the k of polycarbonate. • Maximum processing temperature was 90 °C. • Low temperature enables their use in low-voltage, low-cost, flexible electronics. - Abstract: We report the synthesis of TiO{sub 2} nanoparticles prepared by the hydrolysis of titanium isopropoxide (TTIP) in the presence of a DNA complex for solution processable dielectric composites. The nanoparticles were incorporated as fillers in polycarbonate at low concentrations (1.5, 5 and 7 wt%) to produce hybrid dielectric films with dielectric constant higher than thermally grown silicon oxide. It was found that the DNA complex plays an important role as capping agent in the formation and suspension stability of nanocrystalline anatase phase TiO{sub 2} at room temperature with uniform size (∼6 nm) and narrow distribution. The effective dielectric constant of spin-cast polycarbonate thin-films increased from 2.84 to 13.43 with the incorporation of TiO{sub 2} nanoparticles into the polymer host. These composites can be solution processed with a maximum temperature of 90 °C and could be potential candidates for its application in low-cost macro-electronics.

  1. A study on the improvement of radiation resistance for polymer materials

    Energy Technology Data Exchange (ETDEWEB)

    Park, K. J.; Cho, S. H

    1999-01-01

    DLC (Diamond-like carbon) thin film-deposited polycarbonate specimens were irradiated by high level gamma-ray and made observation of their irradiation effects. In order to do that, diamond-like carbon thin films were deposited on polycarbonate specimens by plasma-enhanced chemical vapor deposition, and then those specimens were irradiated in the high level irradiation facility in KAERI at the same dose rate of 10{sup 6} rad. Relative concentration of free radicals generated during irradiation of the DLC-deposited and undeposited specimens was determined by the analysis of EPR (electron paramagnetic resonance) spectrum at the elapsed time of 4 hours and 2 months after irradiation of those specimens. As a result of the analysis, it was found that the radical concentration in the DLC-undeposited specimen at the elapsed time of 2 months reduced rapidly in 4 % compared with that at the elapsed time of 4 hours, whereas the concentration in the DLC-deposited specimens decreased slowly in the vicinity of 60 %. Consequently, DLC thin film-deposited polycarbonate specimens resulted in the increase of radiation-oxidation resistance.

  2. Theory of Effectiveness Measurement

    National Research Council Canada - National Science Library

    Bullock, Richard K

    2006-01-01

    .... Currently, however, there is no formal foundation for formulating effectiveness measures. This research presents a new framework for effectiveness measurement from both a theoretical and practical view...

  3. Effects of ionizing radiation

    International Nuclear Information System (INIS)

    Tadmor, J.

    1984-05-01

    A sound evaluation of the consequences of releases of radioactivity into the environment, especially of those large amounts, and of the effectiveness of different protective measures, requires thorough concern of the various aspects of the radiological effects. The effects of ionizing radiation were reviewed according to the following characterization: Affected subject (somatic, genetic and psychological effects); Duration of irradiation (acute and chronic irradiation); Latent period (early and late effects); Dose-effect relationship (stochastic and non-stochastic effects); Population affected (e.g. children, pregnant women). In addition to the lethal effects which are generally considered extensively in all the evaluations of the consequences of radioactivity releases, such effects as early symptoms and morbidity are emphasized in this review. The dependence of the effects on dose rates, repair mechanism and medical treatment is discussed, and the uncertainties involved with their evaluation is highlighted. The differences between QF (quality factor) and RBE (relative biological effectiveness) of different radiation sources are interpreted. Synergystic effects and the effectiveness of various means of medication are discussed. It is suggested that all radiological effects, including those resulting from relatively low radiation doses, e.g. foetus deformations, fertility impairment, prodomal - leading to psychological effects, should be considered within the evaluation of the consequences of radioactivity releases and of the effectiveness of protective measures. Limits of the repair factors to be considered within the evaluation of the effects of chronic exposures are proposed

  4. 77 FR 28380 - Agency Information Collection Activities; Submission to OMB for Review and Approval; Comment...

    Science.gov (United States)

    2012-05-14

    ... categories: Polycarbonates (PC) Production, Acrylic and Modacrylic Fibers (AMF) Production, Acetal Resins (AR) Production, and Hydrogen Fluoride (HF) Production. New facilities include those that commenced construction... acetal resin; acrylic and modacrylic fiber; hydrogen fluoride and polycarbonate production. [[Page 28381...

  5. On Effect Size

    Science.gov (United States)

    Kelley, Ken; Preacher, Kristopher J.

    2012-01-01

    The call for researchers to report and interpret effect sizes and their corresponding confidence intervals has never been stronger. However, there is confusion in the literature on the definition of effect size, and consequently the term is used inconsistently. We propose a definition for effect size, discuss 3 facets of effect size (dimension,…

  6. Biological effects of radiation

    International Nuclear Information System (INIS)

    2013-01-01

    This fourth chapter presents: cell structure and metabolism; radiation interaction with biological tissues; steps of the production of biological effect of radiation; radiosensitivity of tissues; classification of biological effects; reversibility, transmissivity and influence factors; pre-natal biological effects; biological effects in therapy and syndrome of acute irradiation

  7. Colossal magnetodielectric effect caused by magnetoelectric effect ...

    Indian Academy of Sciences (India)

    -D laminate composite under low magnetic field. When the composite is placed in an external a.c. magnetic field, magnetoelectric effect is produced, as a result, the dielectric properties of the Pb(Zr,Ti)O3 is changed, i.e. magnetodielectric effect ...

  8. Colossal magnetodielectric effect caused by magnetoelectric effect ...

    Indian Academy of Sciences (India)

    Keywords. Composite materials; electrical properties; magnetodielectric effect; magnetoelectric effect. 1. Introduction. Recently, multiferroic materials have attracted much interest for their coexistence of ferroelectricity, ferromagnetism and ferroelasticity (Kimura et al 2003; Wang et al 2003; Hur et al. 2004; Spaldin and Fiebig ...

  9. Effective Prime Uniqueness

    OpenAIRE

    Cholak, Peter; McCoy, Charlie

    2014-01-01

    Assuming the obvious definitions (see paper) we show the a decidable model that is effectively prime is also effectively atomic. This implies that two effectively prime (decidable) models are computably isomorphic. This is in contrast to the theorem that there are two atomic decidable models which are not computably isomorphic. The implications of this work in reverse mathematics is that "effectively prime implies effectively atomic" holds in topped models. But due to an observation of David ...

  10. How effective is the effective potential?

    International Nuclear Information System (INIS)

    Dodelson, S.; Gradwohl, B.A.

    1993-01-01

    Motivated by bubble nucleation in first order phase transitions, we question the validity of the effective potential for inhomogeneous configurations. In an attempt to get some insight into the importance of derivative terms, we analyze a simple model, a kink in 1+1 dimensions and zero temperature. We evaluate the energy shift from the quantum fluctuations about the non-uniform background (i.e. the effective action) and compare it to the energy from the effective potential. Our results clearly show that for inhomogeneous configurations it may be inadequate to omit derivative terms and confine oneself to the effective potential. We then couple the kink field to an additional scalar field and perform the same comparison. The addition of the second field allows us to vary the mass of the fluctuations and their coupling to the underlying kink. If the mass of the second field is large, it does not feel the inhomogeneities in the kink field and consequently does not give rise to important derivative corrections in the effective action. In contrast, if the mass is small, derivative terms are significant and the effective potential fails. In the latter regime we can, however, rely on the Born approximation to calculate the effective action. (orig.)

  11. DAFX Digital Audio Effects

    CERN Document Server

    2011-01-01

    The rapid development in various fields of Digital Audio Effects, or DAFX, has led to new algorithms and this second edition of the popular book, DAFX: Digital Audio Effects has been updated throughout to reflect progress in the field. It maintains a unique approach to DAFX with a lecture-style introduction into the basics of effect processing. Each effect description begins with the presentation of the physical and acoustical phenomena, an explanation of the signal processing techniques to achieve the effect, followed by a discussion of musical applications and the control of effect parameter

  12. Biological effects of hyperthermia

    International Nuclear Information System (INIS)

    Okumura, Hiroshi

    1980-01-01

    Biological effects of hyperthermia and application of hyperthermia to cancer therapy were outlined. As to independent effects of hyperthermia, heat sensitivity of cancer cells, targets of hyperthermia, thermal tolerance of cancer cells, effects of pH on hyperthermic cell survival, effects of hyperthermia on normal tissues, and possibility of clinical application of hyperthermia were described. Combined effect of hyperthermia and x-irradiation to enhance radiosensitivity of cancer cells, its mechanism, effects of oxygen on cancer cells treated with hyperthermia and irradiation, and therapeutic ratio of combined hyperthermia and irradiation were also described. Finally, sensitizers were mentioned. (Tsunoda, M.)

  13. Modeling quantization effects in field effect transistors

    CERN Document Server

    Troger, C

    2001-01-01

    Numerical simulation in the field of semiconductor device development advanced to a valuable, cost-effective and flexible facility. The most widely used simulators are based on classical models, as they need to satisfy time and memory constraints. To improve the performance of field effect transistors such as MOSFETs and HEMTs these devices are continuously scaled down in their dimensions. Consequently the characteristics of such devices are getting more and more determined by quantum mechanical effects arising from strong transversal fields in the channel. In this work an approach based on a two-dimensional electron gas is used to describe the confinement of the carriers. Quantization is considered in one direction only. For the derivation of a one-dimensional Schroedinger equation in the effective mass framework a non-parabolic correction for the energy dispersion due to Kane is included. For each subband a non-parabolic dispersion relation characterized by subband masses and subband non-parabolicity coeffi...

  14. Modeling the impact of thermal effects on luminous flux maintenance for SSL luminaires

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Lynn [RTI International, Research Triangle Park, NC (United States); Mills, Karmann [RTI International, Research Triangle Park, NC (United States); Lamvik, Michael [RTI International, Research Triangle Park, NC (United States); Solano, Eric [RTI International, Research Triangle Park, NC (United States); Bobashev, Georgiy [RTI International, Research Triangle Park, NC (United States); Perkins, Curtis [RTI International, Research Triangle Park, NC (United States)

    2017-05-30

    Meeting the longevity requirements of solid-state lighting (SSL) devices places extreme demands on the materials and designs that are used in SSL luminaires. Therefore, understanding the aging characteristics of lens, reflectors, and other materials is essential to projecting the long-term performance of LED-based lighting systems. Overlooking these factors at either the design or product specification stage can result in premature failure of the device due to poor luminous flux maintenance and/or excessive chromaticity shifts. This paper describes a methodology for performing accelerated stress testing (AST) on materials intended for use in SSL luminaires. This test methodology, which consists of elevated temperature and humidity conditions, produces accelerated aging data that can be correlated to expected performance under normal luminaire operating conditions. The correlations can then be leveraged to produce models of the changes in the optical properties of key materials including transmittance versus wavelength of lenses and reflectance versus wavelength for housings and other reflectors. This information has been collected into a lumen maintenance decision support tool (LM-DST) and together with user supplied inputs (e.g., expected operation conditions) can provide guidance on lifetime expectations of SSL luminaires. This approach has been applied to a variety of materials commonly found in SSL luminaires including acrylics, polycarbonates, and silicones used for lenses and paints, coatings, films, and composites used for reflectors.

  15. A study to compare the effects of simulated torquing forces on pre-adjusted orthodontic brackets.

    Science.gov (United States)

    McKnight, M M; Jones, S P; Davies, E H

    1994-11-01

    The transmission of torquing forces between three types of preadjusted bracket was investigated. 0.022-inch Roth prescription 'A'-Company (stainless steel), Silkon (reinforced polycarbonate), and Allure III (polycrystalline ceramic) brackets were used. A selection of stainless steel archwires were chosen, 0.018 x 0.025, 0.019 x 0.025, and 0.021 x 0.025 inch. The brackets were torqued with respect to the archwire and force v. angular deflection was recorded on an Instron machine. The dimension of angular change was in part dependent on the ability of the bracket to elastically or plastically deform. There were no significant differences between bracket types with the 0.018 x 0.025-inch archwire. 'A'-Company brackets demonstrated a significantly lower resistance to loading compared to Silkon brackets in the 0.019 x 0.025-inch group. The greatest amount of distortion was seen in Silkon brackets with an 0.021 x 0.025-inch archwire. Allure III brackets demonstrated the greatest resistance to loading in all groups. As no apparent distortion under loading is seen in Allure III brackets, it is assumed that the load is largely transmitted to the tooth. Full thickness stainless steel rectangular wires should be avoided with these brackets, in order to prevent overloading.

  16. Climate Effects on Health

    Science.gov (United States)

    ... Guidance and Trainings Webinars Data and Tools Publications Climate Effects on Health Recommend on Facebook Tweet Share ... effects has been excerpted from the Third National Climate Assessment’s Health Chapter . Additional information regarding the health ...

  17. Multipollutant health effect simulations

    Data.gov (United States)

    U.S. Environmental Protection Agency — Resulting betas (health effects) from a variety of copollutant epidemiologic models used to analyze the impact of exposure measurement error on health effect...

  18. Skills for Effective Consultation.

    Science.gov (United States)

    Dustin, Dick; Ehly, Stewart

    1984-01-01

    Discusses counselor skills that promote effective consultation. Reviews research on effective school consultation and presents a five-stage model which involves phasing in, problem identification, implementation, evaluation, and termination. Provides recommendations for the process and products of consultation. (JAC)

  19. Characteristics of Effective Argumentation.

    Science.gov (United States)

    Frana, Adrian W.

    1989-01-01

    Examines how the 1988 Presidential Debates provide a resource for effective instruction in public argument. Provides several examples of effective (and ineffective) argumentative speaking taken from the debates. (MM)

  20. Medications and Side Effects

    Science.gov (United States)

    ... to fully work. You might feel some side effects of your medication before your feel the benefits – ... as sleepiness, anxiety or headache) is a side effect or a symptom of your illness. Many side ...

  1. Side Effects (Management)

    Science.gov (United States)

    ... cancer care is relieving side effects, called symptom management, palliative care, or supportive care. It is important ... treat them. To learn about the symptoms and management of the long-term side effects of cancer ...

  2. Leadership Effectiveness and Gender

    National Research Council Canada - National Science Library

    Gedney, Christine

    1999-01-01

    This research paper on the subject of Leadership Effectiveness and Gender attempts to conduct a focused amount of research to answer the question about the correlation between gender and leadership effectiveness...

  3. Effects of teacher training

    DEFF Research Database (Denmark)

    Wahlgren, Bjarne; Larsen, Lea Lund

    2010-01-01

    The article gives a short overview over existing knowledge concerning the effect of teacher training in relation to adult learning. It presents a research design for measuring the effect of teacher traning.......The article gives a short overview over existing knowledge concerning the effect of teacher training in relation to adult learning. It presents a research design for measuring the effect of teacher traning....

  4. Special Effects Activity Guide.

    Science.gov (United States)

    Boxer, Jennifer; Valenta, Carol

    This guide accompanies "Special Effects," a 40-minute IMAX film and "Special Effects II", a multimedia, interactive traveling exhibit designed by the California Museum of Science and Industry. The exhibit focuses on the underlying scientific and technical processes of special effects from the earliest motion picture to state-of-the-art digital…

  5. Binary effectivity rules

    DEFF Research Database (Denmark)

    Keiding, Hans; Peleg, Bezalel

    2006-01-01

    effectivity rule is regular if it is the effectivity rule of some regular binary SCR. We characterize completely the family of regular binary effectivity rules. Quite surprisingly, intrinsically defined von Neumann-Morgenstern solutions play an important role in this characterization...

  6. Magnetic effects in electrochemistry

    Directory of Open Access Journals (Sweden)

    NEBOJSA D. NIKOLIC

    2005-05-01

    Full Text Available The effect of imposed magnetic fields onto the electrodeposition of magnetic (nickel and non – magnetic (copper metals was analysed. Also, magnetic properties of electrochemically obtained nanocontacts were examined. An effort to establish a possible correlation between the morphologies of the nanocontacts and the effect of the very large ballistic magnetoresistance (BMR effect was made.

  7. Phylogenetic effective sample size.

    Science.gov (United States)

    Bartoszek, Krzysztof

    2016-10-21

    In this paper I address the question-how large is a phylogenetic sample? I propose a definition of a phylogenetic effective sample size for Brownian motion and Ornstein-Uhlenbeck processes-the regression effective sample size. I discuss how mutual information can be used to define an effective sample size in the non-normal process case and compare these two definitions to an already present concept of effective sample size (the mean effective sample size). Through a simulation study I find that the AICc is robust if one corrects for the number of species or effective number of species. Lastly I discuss how the concept of the phylogenetic effective sample size can be useful for biodiversity quantification, identification of interesting clades and deciding on the importance of phylogenetic correlations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Network effects in railways

    DEFF Research Database (Denmark)

    Landex, Alex

    2012-01-01

    . Therefore, sections 3 and 4 describe the network effects for passengers and how they can be measured using passenger delay models. Before the concluding remarks in section 6, section 5 discusses how the operation can be improved by examining network effects in the planning process. © 2012 WIT Press....... each other everywhere in the network. First this paper describes network effects in general (section 1). In section 2 the network effects for trains and how they can be measured by scheduled waiting time is described. When the trains are affected by network effects the passengers are also affected......Railway operation is often affected by network effects as a change in one part of the network can influence other parts of the network. Network effects occur because the train runs may be quite long and since the railway system has a high degree of interdependencies as trains cannot cross/overtake...

  9. Biological radiation effects

    International Nuclear Information System (INIS)

    Gomes, R.A.

    1976-01-01

    The stages of processes leading to radiation damage are studied, as well as, the direct and indirect mechanics of its production. The radiation effects on nucleic acid and protein macro moleculas are treated. The physical and chemical factors that modify radiosensibility are analysed, in particular the oxygen effects, the sensibilization by analogues of nitrogen bases, post-effects, chemical protection and inherent cell factors. Consideration is given to restoration processes by excision of injured fragments, the bloching of the excision restoration processes, the restoration of lesions caused by ionizing radiations and to the restoration by genetic recombination. Referring to somatic effects of radiation, the early ones and the acute syndrome of radiation are discussed. The difference of radiosensibility observed in mammalian cells and main observable alterations in tissues and organs are commented. Referring to delayed radiation effects, carcinogeneses, alterations of life span, effects on growth and development, as well as localized effects, are also discussed [pt

  10. EFFECTS OF EFFECTS OF PARTICLE SIZE DISTRIBUTION ...

    African Journals Online (AJOL)

    eobe

    Bioremediation has been proven to be the most effective method of cleaning up oil contaminated soils through the application of nutrients and microor the application of nutrients and microorganism. Hence, this ganism. Hence, this ganism. Hence, this research presents the research presents the research presents the ...

  11. The effective action

    International Nuclear Information System (INIS)

    DeWitt, B.

    1987-01-01

    The concept of the effective action in quantum field theory was introduced into physics by Julian Schwinger in 1954. The effective action summarizes, in a single functional, all the quantum properties of the fields under consideration. The functional derivative of the effective action yields the effective field equations, which replace the classical field equations as descriptors of the dynamical behavior of quantized fields. Solutions of these equations are 'in-out' matrix elements of the field operators and, when substituted back into the effective action itself, yield logarithms of the corresponding 'in-out' amplitudes. The classical field equations are gauge covariant, a fact that derives from the gauge invariance of the classical action. One has learned how to construct effective actions that are similarly gauge invariant (in each order of perturbation theory) and that yield effective field equations having the covariance properties of their classical analogs. Despite this advance, problems remain, stemming from the fact that there is not one but an infinite number of gauge invariant effective actions, one for every background-covariant choice of supplementary conditions and ghost fields. Vilkovisky (1984) has argued persuasively that by requiring additionally that the effective action be invariant under local invertible changes in the choice of basic field variables, one can construct a natural unique gauge invariant effective action. This lecture will examine Vilkovisky's ideas. 3 refs

  12. The Aid Effectiveness Literature

    DEFF Research Database (Denmark)

    Doucouliagos, Hristos; Paldam, Martin

    The AEL consists of empirical macro studies of the effects of development aid. At the end of 2004 it had reached 97 studies of three families, which we have summarized in one study each using meta-analysis. Studies of the effect on investments show that they rise by 1/3 of the aid – the rest...... is crowded out by a fall in savings. Studies of the effect on growth show an insignificant positive effect. Studies of the effect on growth, conditional on something else, have till now shown weak results. The Dutch Disease effect of aid has been ignored. The best aggregate estimate is that since its start...... in the early 1960s aid has increased the standard of living in the poor countries by 20%....

  13. The Hubble effective potential

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, T.M.; Miao, S.P.; Prokopec, T. [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, Leuvenlaan 4, Postbus 80.195, 3508 TD Utrecht (Netherlands); Woodard, R.P., E-mail: T.M.Janssen@uu.nl, E-mail: S.Miao@uu.nl, E-mail: T.Prokopec@uu.nl, E-mail: woodard@phys.ufl.edu [Department of Physics, University of Florida, Gainesville, FL 32611 (United States)

    2009-05-15

    We generalize the effective potential to scalar field configurations which are proportional to the Hubble parameter of a homogeneous and isotropic background geometry. This may be useful in situations for which curvature effects are significant. We evaluate the one loop contribution to the Hubble Effective Potential for a massless scalar with arbitrary conformal and quartic couplings, on a background for which the deceleration parameter is constant. Among other things, we find that inflationary particle production leads to symmetry restoration at late times.

  14. Leadership Effectiveness and Gender

    National Research Council Canada - National Science Library

    Gedney, Christine

    1999-01-01

    .... It specifically looks at the current definitions of leadership and looks at some historical background information relating to the more common theories that relate to leadership and effectiveness...

  15. Impedance and Collective Effects

    CERN Document Server

    Metral, E; Rumolo, R; Herr, W

    2013-01-01

    This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Chapter '4 Impedance and Collective Effects' with the content: 4 Impedance and Collective Effects Introduction 4.1 Space Charge 4.2 Wake Fields and Impedances 4.3 Coherent Instabilities 4.4 Landau Damping 4.5 Two-Stream Effects (Electron Cloud and Ions) 4.6 Beam-Beam Effects 4.7 Numerical Modelling

  16. Secondary hydrogen isotope effects

    International Nuclear Information System (INIS)

    Melander, L.; Sonders, U.

    1983-01-01

    Secondary isotope effects can be produced by isotopes of elements heavier than hydrogen, but secondary isotope effects of hydrogen are of greater interest, because they are larger and can be measured easier. Such aspects of the problem as solvolytic reactions (in the case of α-position and β-position in organic compounds), reactions of compounds with deuterium remoted from reaction centre, with deuterium in nonsaturated compounds, participation of neighbouring groups in the reaction, are considered. Besides, steric isotope effects and inductive isotope effects are considered

  17. Effects of Leadership Roles on Team Effectiveness

    OpenAIRE

    Ethem Duygulu; Nurcan Ciraklar

    2009-01-01

    In this study we aim to explain the patterns of leadership roles for team effectiveness in non profit organizations compared to economic organizations. For this purpose, we studied three successful organization types, i.e the amateur sports clubs (football, basketball), theater companies and, regional folk groups. Our basic hypothesis is that the relationship between the type of organization (specially teams) and the role of leadership is not random. Therefore, we believe that an empirical ap...

  18. Presenting Food Science Effectively

    Science.gov (United States)

    Winter, Carl K.

    2016-01-01

    While the need to present food science information effectively is viewed as a critical competency for food scientists by the Institute of Food Technologists, most food scientists may not receive adequate training in this area. Effective presentations combine both scientific content and delivery mechanisms that demonstrate presenter enthusiasm for…

  19. Adverse effects of bisphosphonates

    DEFF Research Database (Denmark)

    Abrahamsen, Bo

    2010-01-01

    and are tolerated by the majority of patients, but serious adverse events have been recorded in some cases. Only the most common of adverse effects are robustly observable in clinical trials. In general, studies were not powered to detect effects that were lower in incidence than fractures. This review of adverse...

  20. Experiences with effects specifications

    DEFF Research Database (Denmark)

    Simonsen, Jesper; Hertzum, Morten; Barlach, Anders

    2011-01-01

    We describe the effects-specification process from a project that was conducted during the fall 2010 and spring of 2011 in this chapter. The project configured and implemented an electronic patient record system at a maternity ward at a hospital located in a European region. The process comprised...... for measuring effects were designed. The project is analyzed and lessons learned are discussed....

  1. Safeguards system effectiveness modeling

    International Nuclear Information System (INIS)

    Bennett, H.A.; Boozer, D.D.; Chapman, L.D.; Daniel, S.L.; Engi, D.; Hulme, B.L.; Varnado, G.B.

    1976-01-01

    A general methodology for the comparative evaluation of physical protection system effectiveness at nuclear facilities is presently under development. The approach is applicable to problems of sabotage or theft at fuel cycle facilities. The overall methodology and the primary analytic techniques used to assess system effectiveness are briefly outlined

  2. Safeguards system effectiveness modeling

    International Nuclear Information System (INIS)

    Bennett, H.A.; Boozer, D.D.; Chapman, L.D.; Daniel, S.L.; Engi, D.; Hulme, B.L.; Varnado, G.B.

    1976-01-01

    A general methodology for the comparative evaluation of physical protection system effectiveness at nuclear facilities is presently under development. The approach is applicable to problems of sabotage or theft at fuel cycle facilities. In this paper, the overall methodology and the primary analytic techniques used to assess system effectiveness are briefly outlined

  3. The greenhouse effect gases

    International Nuclear Information System (INIS)

    2006-06-01

    This road-map proposes by the Group Total aims to inform the public on the greenhouse effect gases. It presents the greenhouses effect as a key component of the climate system, the impacts of the human activity, the foreseeable consequences of global warming, the Kyoto protocol and Total commitment in the domain. (A.L.B.)

  4. Isotopic effect giant resonances

    International Nuclear Information System (INIS)

    Buenerd, M.; Lebrun, D.; Martin, P.; Perrin, G.; Saintignon, P. de; Chauvin, J.; Duhamel, G.

    1981-10-01

    The systematics of the excitation energy of the giant dipole, monopole, and quadrupole resonances are shown to exhibit an isotopic effect. For a given element, the excitation energy of the transition decreases faster with the increasing neutron number than the empirical laws fitting the overall data. This effect is discussed in terms of the available models

  5. Relative Effects at Work

    NARCIS (Netherlands)

    Braeken, Johan; Mulder, Joris; Wood, Stephen

    2015-01-01

    Assessing the relative importance of predictors has been of historical importance in a variety of disciplines including management, medicine, economics, and psychology. When approaching hypotheses on the relative ordering of the magnitude of predicted effects (e.g., the effects of discrimination

  6. RBE for deterministic effects

    International Nuclear Information System (INIS)

    1990-01-01

    In the present report, data on RBE values for effects in tissues of experimental animals and man are analysed to assess whether for specific tissues the present dose limits or annual limits of intake based on Q values, are adequate to prevent deterministic effects. (author)

  7. Aristotle and Double Effect

    DEFF Research Database (Denmark)

    Di Nucci, Ezio

    2014-01-01

    cases from the literature on double effect such as, amongst others, strategic bombing, the trolley problem, and craniotomy. I find that, despite some common features such as the dilemmatic structure and the inevitability of a bad effect, Aristotle’s mixed actions do not count as cases justifiable...

  8. Radiation effects in space

    International Nuclear Information System (INIS)

    Fry, R.J.M.

    1987-07-01

    As more people spend more time in space, and the return to the moon and exploratory missions are considered, the risks require continuing examination. The effects of microgravity and radiation are two potential risks in space. These risks increase with increasing mission duration. This document considers the risk of radiation effects in space workers and explorers. 17 refs., 1 fig., 4 tabs

  9. The greenhouse effect

    International Nuclear Information System (INIS)

    2004-01-01

    In the framework of the sustainable development, this paper presents the greenhouse effect and its impact on the climatic change, the world interest from Rio to Buenos Aires, the human activities producing the carbon dioxide and responsible of the greenhouse effect, the carbon dioxide emission decrease possibilities and shows the necessity of the electric power producers contribution. (A.L.B.)

  10. Microscopic dynamical Casimir effect

    Science.gov (United States)

    Souza, Reinaldo de Melo e.; Impens, François; Neto, Paulo A. Maia

    2018-03-01

    We consider an atom in its ground state undergoing a nonrelativistic oscillation in free space. The interaction with the electromagnetic quantum vacuum leads to two effects to leading order in perturbation theory. When the mechanical frequency is larger than the atomic transition frequency, the dominant effect is the motion-induced transition to an excited state with the emission of a photon carrying the excess energy. We compute the angular distribution of emitted photons and the excitation rate. On the other hand, when the mechanical frequency is smaller than the transition frequency, the leading-order effect is the parametric emission of photon pairs, which constitutes the microscopic counterpart of the dynamical Casimir effect. We discuss the properties of the microscopic dynamical Casimir effect and build a connection with the photon production by an oscillating macroscopic metallic mirror.

  11. Effective field theories

    CERN Document Server

    Petrov, Alexey A

    2016-01-01

    This book is a broad-based text intended to help the growing student body interested in topics such as gravitational effective theories, supersymmetric effective theories, applications of effective theory techniques to problems in condensed matter physics (superconductivity) and quantum chromodynamics (such as soft-collinear effective theory). It begins with a review of the use of symmetries to identify the relevant degrees of freedom in a problem, and then presents a variety of methods that can be used to solve physical problems. A detailed discussion of canonical examples of effective field theories with increasing complexity is then conducted. Special cases such as supersymmetry and lattice EFT are discussed, as well as recently-found applications to problems in gravitation and cosmology. An appendix includes various factoids from group theory and other topics that are used throughout the text, in an attempt to make the book self-contained.

  12. Nocebo effect in dermatology

    Directory of Open Access Journals (Sweden)

    Sidharth Sonthalia

    2015-01-01

    Full Text Available Nocebo effect, originally denoting the negative counterpart of the placebo phenomenon, is now better defined as the occurrence of adverse effects to a therapeutic intervention because the patient expects them to develop. More commonly encountered in patients with a past negative experience, this effect stems from highly active processes in the central nervous system, mediated by specific neurotransmitters and modulated by psychological mechanisms such as expectation and conditioning. The magnitude of nocebo effect in clinical medicine is being increasingly appreciated and its relevance encompasses clinical trials as well as clinical practice. Although there is hardly any reference to the term nocebo in dermatology articles, the phenomenon is encountered routinely by dermatologists. Dermatology patients are more susceptible to nocebo responses owing to the psychological concern from visibility of skin lesions and the chronicity, unpredictable course, lack of ′permanent cure′ and frequent relapses of skin disorders. While finasteride remains the prototypical drug that displays a prominent nocebo effect in dermatologic therapeutics, other drugs such as isotretinoin are also likely inducers. This peculiar phenomenon has recently been appreciated in the modulation of itch perception and in controlled drug provocation tests in patients with a history of adverse drug reactions. Considering the conflict between patients′ right to information about treatment related adverse effects and the likelihood of nocebo effect stemming from information disclosure, the prospect of ethically minimizing nocebo effect remains daunting. In this article, we review the concept of nocebo effect, its postulated mechanism, relevance in clinical dermatology and techniques to prevent it from becoming a barrier to effective patient management.

  13. [Psychoanalysis and Side Effect].

    Science.gov (United States)

    Shirahase, Joichiro

    2015-01-01

    A study of psychoanalysis from the perspective of side effects reveals that its history was a succession of measures to deal with its own side effects. This, however, does not merely suggest that, as a treatment method, psychoanalysis is incomplete and weak: rather, its history is a record of the growth and development of psychoanalysis that discovered therapeutic significance from phenomena that were initially regarded as side effects, made use of these discoveries, and elaborated them as a treatment method. The approach of research seen during the course of these developments is linked to the basic therapeutic approach of psychoanalysis. A therapist therefore does not draw conclusions about a patient's words and behaviors from a single aspect, but continues to make efforts to actively discover a variety of meanings and values from them, and to make the patient's life richer and more productive. This therapeutic approach is undoubtedly one of the unique aspects of psychoanalysis. I discuss the issue of psychoanalysis and side effects with the aim of clarifying this unique characteristic of psychoanalysis. The phenomenon called resistance inevitably emerges during the process of psychoanalytic treatment. Resistance can not only obstruct the progress of therapy; it also carries the risk of causing a variety of disadvantages to the patient. It can therefore be seen as an adverse effect. However, if we re-examine this phenomenon from the perspective of transference, we find that resistance is in fact a crucial tool in psychoanalysis, and included in its main effect, rather than a side effect. From the perspective of minimizing the character of resistance as a side effect and maximizing its character as a main effect, I have reviewed logical organization, dynamic evaluation, the structuring of treatment, the therapist's attitudes, and the training of therapists. I conclude by stating that psychoanalysis has aspects that do not match the perspective known as a side

  14. Creating more effective graphs

    CERN Document Server

    Robbins, Naomi B

    2012-01-01

    A succinct and highly readable guide to creating effective graphs The right graph can be a powerful tool for communicating information, improving a presentation, or conveying your point in print. If your professional endeavors call for you to present data graphically, here's a book that can help you do it more effectively. Creating More Effective Graphs gives you the basic knowledge and techniques required to choose and create appropriate graphs for a broad range of applications. Using real-world examples everyone can relate to, the author draws on her years of experience in gr

  15. Cohomology of Effect Algebras

    Directory of Open Access Journals (Sweden)

    Frank Roumen

    2017-01-01

    Full Text Available We will define two ways to assign cohomology groups to effect algebras, which occur in the algebraic study of quantum logic. The first way is based on Connes' cyclic cohomology. The resulting cohomology groups are related to the state space of the effect algebra, and can be computed using variations on the Kunneth and Mayer-Vietoris sequences. The second way involves a chain complex of ordered abelian groups, and gives rise to a cohomological characterization of state extensions on effect algebras. This has applications to no-go theorems in quantum foundations, such as Bell's theorem.

  16. The effective nuclear potential

    International Nuclear Information System (INIS)

    Skyrme, T.H.R.

    1994-01-01

    An empirical analyses is made of the mean effective internucleon potential required in the shell-model description of nuclei, allowing for the presence of many-body effects as suggested by current theory. A consistent description is found in which the effective two-body interaction acts almost entirely in even states, and the many-body effects are simulated by a repulsive three-body contact interaction. The strength of the two-body interaction is consistent with that expressed by the free scattering matrix of the two-nucleon system, and that of the three-body interaction with the 'rearrangement energy' calculated in the many-body theory. (author). 21 refs, 2 figs, 7 tabs

  17. Theory of Effectiveness Measurement

    National Research Council Canada - National Science Library

    Bullock, Richard K

    2006-01-01

    Effectiveness measures provide decision makers feedback on the impact of deliberate actions and affect critical issues such as allocation of scarce resources, as well as whether to maintain or change existing strategy...

  18. Radiation effects in space

    International Nuclear Information System (INIS)

    Fry, R.J.M.

    1986-01-01

    The paper discusses the radiation environment in space that astronauts are likely to be exposed to. Emphasis is on proton and HZE particle effects. Recommendations for radiation protection guidelines are presented

  19. Side Effects: Appetite Loss

    Science.gov (United States)

    Cancer treatments may lower your appetite. Side effects such as nausea, fatigue, or mouth sores can also making eating difficult. Learn how to eat well to avoid losing weight or becoming dehydrated, so you stay strong during treatment.

  20. Side Effects: Fatigue

    Science.gov (United States)

    Fatigue is a common side effect of many cancer treatments such as chemotherapy, radiation therapy, immunotherapy, and surgery. Anemia and pain can also cause fatigue. Learn about symptoms and way to manage fatigue.