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Sample records for beam cured composites

  1. Electron beam curing of polymer matrix composites

    International Nuclear Information System (INIS)

    Janke, C.J.; Wheeler, D.; Saunders, C.

    1998-01-01

    The purpose of the CRADA was to conduct research and development activities to better understand and utilize the electron beam PMC curing technology. This technology will be used to replace or supplement existing PMC thermal curing processes in Department of Energy (DOE) Defense Programs (DP) projects and American aircraft and aerospace industries. This effort involved Lockheed Martin Energy Systems, Inc./Lockheed Martin Energy Research Corp. (Contractor), Sandia National Laboratories, and ten industrial Participants including four major aircraft and aerospace companies, three advanced materials companies, and three electron beam processing organizations. The technical objective of the CRADA was to synthesize and/or modify high performance, electron beam curable materials that meet specific end-use application requirements. There were six tasks in this CRADA including: Electron beam materials development; Electron beam database development; Economic analysis; Low-cost Electron Beam tooling development; Electron beam curing systems integration; and Demonstration articles/prototype structures development. The contractor managed, participated and integrated all the tasks, and optimized the project efforts through the coordination, exchange, and dissemination of information to the project participants. Members of the Contractor team were also the principal inventors on several electron beam related patents and a 1997 R and D 100 Award winner on Electron-Beam-Curable Cationic Epoxy Resins. The CRADA achieved a major breakthrough for the composites industry by having successfully developed high-performance electron beam curable cationic epoxy resins for use in composites, adhesives, tooling compounds, potting compounds, syntactic foams, etc. UCB Chemicals, the world's largest supplier of radiation-curable polymers, has acquired a license to produce and sell these resins worldwide

  2. Electron beam curing of composites in North America

    International Nuclear Information System (INIS)

    Berejka, Anthony J.; Eberle, Cliff

    2002-01-01

    Electron beam curing of fiber-reinforced composites was explored over 30 years ago. Since then there have been developments in accelerator technology, in processes for handling materials presented to an accelerator, and in materials that can be used as matrix binders. In recent years in North America, Cooperative Research and Development Agreements (CRADAs) have been formed involving collaboration amongst materials suppliers, accelerator manufacturers and service providers, national laboratories, such as Oak Ridge National Laboratory, and interested potential users. The scope and status of these CRADAs are reviewed along with other recent developments in the electron beam curing of composites in North America. Innovative and proprietary materials technology has been developed and progress made toward implementing commercial practice. Significant market interest has developed in the military/aerospace industries that are finding the process and performance of electron beam cured composites to offer significant benefits

  3. Gamma and electron beam curing of polymers and composites

    International Nuclear Information System (INIS)

    Saunders, C.B.; Dickson, L.W.; Singh, A.

    1987-01-01

    Radiation polymerization has helped us understand polymer chemistry, and is also playing an increasing role in the field of practical applications. Radiation curing has a present market share of about 5% of the total market for curing of polymers and composites and the annual growth rate of the radiation curing market is ≥20% per year. Advantages of radiation curing over thermal or chemical curing methods include: improved control of the curing rate, reduced curing times, curing at ambient temperatures, curing without the need for chemical initiators, and complete (100%) curing with minimal toxic chemical emissions. Radiation treatment may also be used to effect crosslinking and grafting of polymer and composite materials. The major advantage in these cases is the ability to process products in their final shape. Cable insulation, automotive and aircraft components, and improved construction materials are some of the current and near-future industrial applications of radiation curing and crosslinking. 19 refs

  4. Critical parameters for electron beam curing of cationic epoxies and property comparison of electron beam cured cationic epoxies versus thermal cured resins and composites

    International Nuclear Information System (INIS)

    Janke, C.J.; Norris, R.E.; Yarborough, K.; Lopata, V.J.

    1997-01-01

    Electron beam curing of composites is a nonthermal, nonautoclave curing process offering the following advantages compared to conventional thermal curing: substantially reduced manufacturing costs and curing times; improvements in part quality and performance; reduced environmental and health concerns; and improvements in material handling. In 1994 a Cooperative Research and Development Agreement (CRADA), sponsored by the Department of Energy Defense Programs and 10 industrial partners, was established to advance electron beam curing of composites. The CRADA has successfully developed hundreds of new toughened and untoughened resins, offering unlimited formulation and processing flexibility. Several patent applications have been filed for this work. Composites made from these easily processable, low shrinkage material match the performance of thermal cured composites and exhibit: low void contents comparable to autoclave cured composites (less than 1%); superb low water absorption values in the same range as cyanate esters (less than 1%); glass transition temperatures rivaling those of polyimides (greater than 390 C); mechanical properties comparable to high performance, autoclave cured composites; and excellent property retention after cryogenic and thermal cycling. These materials have been used to manufacture many composite parts using various fabrication processes including hand lay-up, tow placement, filament winding, resin transfer molding and vacuum assisted resin transfer molding

  5. Electron Beam Curing of Polymer Matrix Composites - CRADA Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Janke, C. J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howell, Dave [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Norris, Robert E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    1997-05-01

    The major cost driver in manufacturing polymer matrix composite (PMC) parts and structures, and one of the elements having the greatest effect on their quality and performance, is the standard thermal cure process. Thermal curing of PMCs requires long cure times and high energy consumption, creates residual thermal stresses in the part, produces volatile toxic by-products, and requires expensive tooling that is tolerant of the high cure temperatures.

  6. Efficient composite fabrication using electron-beam rapidly cured polymers engineered for several manufacturing processes

    International Nuclear Information System (INIS)

    Walton, T.C.; Crivello, J.V.

    1995-01-01

    Low cost, efficiently processed ultra high specific strength and stiffness graphite fiber reinforced polymeric composite materials are of great interest to commercial transportation, construction and aerospace industries for use in various components with enhanced degrees of weight reduction, corrosion/erosion resistance and fatigue resistance. 10 MeV Electron Beam cure processing has been found to increase the cure rate by an order of magnitude over thermally cured systems yet provide less molded in stresses and high T g s. However, a limited range of resins are available which are easily processed with low shrinkage and with performance properties equal or exceeding those of state of the art toughened epoxies and BMI's. The technology, introduced by an academia-industry partnership sparked by Langley Research Center utilizes a cost effective, rapid curing polymeric composite processing technique which effectively reduces the need for expensive tooling and energy inefficient autoclave processing and can cure the laminate in seconds (compared to hours for thermal curing) in ambient or sub-ambient conditions. The process is based on electron beam (E-Beam) curing of a new series of (65 to 1,000,000 cPs.) specially formulated resins that have been shown to exhibit excellent mechanical and physical properties once cured. Fabrication processes utilizing these specially formulated and newly commercialized resins, (e.g. including Vacuum Assist Resin Transfer molding (VARTM), vacuum bag prepreg layup, pultrusion and filament winding grades) are engineered to cure with low shrinkage, provide excellent mechanical properties, be processed solventless (environmentally friendly) and are inherently non toxic

  7. Beam in on curing

    International Nuclear Information System (INIS)

    Holl, Dr.

    1981-01-01

    Electron beam curing of paints and allied materials is discussed. Examples of applications are: silicone papers; painting of metal; bonding of flake adhesives; bonding of grinding media (binders); paints for external uses; painting shaped parts; bi-reactive painting systems. An example is given of the calculation of the cost of irradiation. (U.K.)

  8. Qualitative Beam Profiling of Light Curing Units for Resin Based Composites.

    Science.gov (United States)

    Haenel, Thomas; Hausnerová, Berenika; Steinhaus, Johannes; Moeginger, Ing Bernhard

    2016-12-01

    This study investigates two technically simple methods to determine the irradiance distribution of light curing units that governs the performance of a visible-light curing resin-based composites. Insufficient light irradiation leads to under-cured composites with poor mechanical properties and elution of residual monomers. The unknown irradiance distribution and its effect on the final restoration are the main critical issues requiring highly sophisticated experimental equipment. The study shows that irradiance distributions of LCUs can easily be determined qualitatively with generally available equipment. This significantly helps dentists in practices to be informed about the homogeneity of the curing lights. Copyright© 2016 Dennis Barber Ltd.

  9. CRADA Final Report for CRADA No. ORNL99-0544, Interfacial Properties of Electron Beam Cured Composites

    Energy Technology Data Exchange (ETDEWEB)

    Janke, C.J.

    2005-10-17

    Electron beam (EB) curing is a technology that promises, in certain applications, to deliver lower cost and higher performance polymer matrix composite (PMC) structures compared to conventional thermal curing processes. PMCs enhance performance by making products lighter, stronger, more durable, and less energy demanding. They are essential in weight- and performance-dominated applications. Affordable PMCs can enhance US economic prosperity and national security. US industry expects rapid implementation of electron beam cured composites in aircraft and aerospace applications as satisfactory properties are demonstrated, and implementation in lower performance applications will likely follow thereafter. In fact, at this time and partly because of discoveries made in this project, field demonstrations are underway that may result in the first fielded applications of electron beam cured composites. Serious obstacles preventing the widespread use of electron beam cured PMCs in many applications are their relatively poor interfacial properties and resin toughness. The composite shear strength and resin toughness of electron beam cured carbon fiber reinforced epoxy composites were about 25% and 50% lower, respectively, than those of thermally cured composites of similar formulations. The essential purpose of this project was to improve the mechanical properties of electron beam cured, carbon fiber reinforced epoxy composites, with a specific focus on composite shear properties for high performance aerospace applications. Many partners, sponsors, and subcontractors participated in this project. There were four government sponsors from three federal agencies, with the US Department of Energy (DOE) being the principal sponsor. The project was executed by Oak Ridge National Laboratory (ORNL), NASA and Department of Defense (DOD) participants, eleven private CRADA partners, and two subcontractors. A list of key project contacts is provided in Appendix A. In order to properly

  10. Beam in on curing

    International Nuclear Information System (INIS)

    Holl, Dr.

    1981-01-01

    This third part of an article on the electron beam curing of paints covers the following aspects: inertising equipment; working without inert gas; increase in temperature when irradiating; irradiating plants; laboratory plants; plant operating from coil to coil; plant for shaped parts; possible applications; decorative films, paper, PVC; packaging material; metallisation of paper films; film bonding; strengthening of flock; coating; pressure sensitive adhesives. (U.K.)

  11. Electron beam curing of coatings

    International Nuclear Information System (INIS)

    Schmidt, J.; Mai, H.

    1986-01-01

    Modern low-energy electron beam processors offer the possibility for high-speed curing of coatings on paper, plastics, wood and metal. Today the electron beam curing gets more importance due to the increasing environmental problems and the rising cost of energy. For an effective curing process low-energy electron beam processors as well as very reactive binders are necessary. Generally such binders consist of acrylic-modified unsaturated polyester resins, polyacrylates, urethane acrylates or epoxy acrylates and vinyl monomers, mostly multifunctional acrylates. First results on the production of EBC binders on the base of polyester resins and vinyl monomers are presented. The aim of our investigations is to obtain binders with curing doses ≤ 50 kGy. In order to reduce the curing dose we studied mixtures of resins and acrylates. (author)

  12. Electron beam-cured coating

    International Nuclear Information System (INIS)

    Kishi, Naoyuki

    1976-01-01

    The method for hardening coatings by the irradiation with electron beams is reviewed. The report is divided into seven parts, namely 1) general description and characteristics of electron beam-cured coating, 2) radiation sources of curing, 3) hardening conditions and reaction behaviour, 4) uses and advantages, 5) latest trends of the industry, 6) practice in the field of construction materials, and 7) economy. The primary characteristics of the electron beam hardening is that graft reaction takes place between base resin and coating to produce strong adhesive coating without any pretreatment. A variety of base resins are developed. High class esters of acrylic acid monomers and methacrylic acid monomers are mainly used as dilutants recently. At present, scanning type accelerators are used, but the practical application of the system producing electron beam of curtain type is expected. The dose rate dependence, the repetitive irradiation and the irradiation atmosphere are briefly described. The filed patent applications on the electron beam hardening were analyzed by the officer of Japan Patent Agency. The production lines for coatings by the electron beam hardening in the world are listed. In the electron beam-cured coating, fifty percent of given energy is consumed effectively for the electron beam hardening, and the solvents discharged from ovens and polluting atmosphere are not used, because the paints of high solid type is used. The running costs of the electron beam process are one sixth of the thermal oven process. (Iwakiri, K.)

  13. Spectroscopic studies of organic-inorganic composite film cured by low energy electron beam

    International Nuclear Information System (INIS)

    Mahathir Mohamed; Dahlan Mohd; Ibrahim Abdullah; Eda Yuhana Ariffin

    2009-01-01

    Liquid epoxidized natural rubber acrylate (LENRA) film was reinforced with silica particles formed in-situ via sol gel process. Combination of these two components produces organic-inorganic composites. Tetraethyl orthosilicate (TEOS) was used as precursor material for silica generation. Sol gel reactions was carried out at different concentrations of TEOS i.e. between 10 and 50 phr. The compounds that contain silica were crosslinked by electron beam. Structural properties studies were carried out by Fourier Transform Infrared Spectrometer (FTIR). It was found that miscibility between organic and inorganic components improved with the presence of silanol groups (Si-OH) and polar solvent i.e. THF, via hydrogen bonding formation between siloxane and LENRA. Morphology study by the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed in-situ generated silica particles were homogenous and well dispersed at any concentrations of TEOS. (author)

  14. Fabrication of low cost high performance large size composite structures by electron beam curing (EBC); Denshisen koka (EBC) ni yoru tei cost koseino ogata fukugozai kozo no seizo

    Energy Technology Data Exchange (ETDEWEB)

    Kamimura, K.; Parrot, P.

    1996-03-15

    This article introduces the electron beam curing (EBC), which is high speed non-heating cure technique for the high performance resin for structures, conducted by Aerospacial Co., Ltd. In this technique, very strong electron beam and X-ray are used in response to the thickness of curing region of members, and the muzzle has energy of 10 MeV as permeation control energy and power of 20 kW as cure time control power. Advantages of fabrication of composite products by EBC is derived from the elimination of exoergic and heating curing processes and the local cure molding. For the EBC, the residual stress is not generated, the size is stable, the insertion of different materials is easy without mismatch of thermal expansion between the composites and metals, the homogeneous bridge can be obtained to stabilize the material quality, the processing time can be shortened, it is suitable to mass production, and the cure of products can be controlled. About 30% to 40% of the cost of products can be reduced. 1 ref., 6 figs., 1 tab.

  15. Electron beam curing of coating

    International Nuclear Information System (INIS)

    Fujioka, S.; Fujikawa, Z.

    1974-01-01

    Electron beam curing (EBC) method, by which hardened coating film is obtained by polymerizing and cross-linking paint with electron beam, has finally reached industrialized stage. While about seven items such as short curing time, high efficiency of energy consumption, and homogeneous curing are enumerated as the advantages of EBC method, it has limitations of the isolation requirement from air needing the injection of inert gas, and considerable amount of initial investment. In the electron accelerators employed in EBC method, the accelerating voltage is 250 to 750 kV, and the tube current is several tens of mA to 200 mA. As an example of EBC applications, EBC ''Erio'' steel sheet was developed by the cooperative research of Nippon Steel Corp., Dai-Nippon Printing Co. and Toray Industries, Inc. It is a high-class pre-coated metal product made from galvanized steel sheets, and the flat sheets with cured coating are sold, and final products are fabricated by being worked in various shapes in users. It seems necessary to develop the paint which enables to raise added value by adopting the EBC method. (Wakatsuki, Y.)

  16. Electron beam curing - taking good ideas to the manufacturing floor

    International Nuclear Information System (INIS)

    Saunders, C.; Lopata, V.; Barnard, J.; Stepanik, T.

    2000-01-01

    Acsion is exploiting several emerging electron beam EB applications ranging from composite curing and repair to viscose manufacturing. EB curing of composite structures offers several advantages: significantly reduced curing times; improvements in part quality and performance; reduced environmental and health concerns; improvements in material handling; and reduced overall manufacturing costs compared to thermal curing. The aerospace industry is developing EB technology in all of their market sectors, including military aviation and space products. Some specific products include cryogenic fuel tanks, improved canopy frames for jet aircraft, and the all-composite military aircraft. This paper discusses each of these opportunities. (author)

  17. Electron beam curing of EPDM

    International Nuclear Information System (INIS)

    Vroomen, G.L.M.; Visser, G.W.; Gehring, J.

    1991-01-01

    Normally EPDM rubbers are vulcanized by systems based on sulphur, resin or peroxide. The common feature of these systems is that they all require activator energy in the form of heat. The (extremely) high temperatures (approximately 180C) have the disadvantage that the final properties of the finished product may be affected in one way or another by a variety of uncontrolled side reactions which may occur. Radiation curing, on the other hand, is a process which differs from those mentioned above in that the final curing is carried out at about 20C under closely controlled conditions (such as radiation dose, penetration depth, etc.), and this form of curing ultimately results in a more well-defined end product. In the rubber industry, this technique is used by large rubber processors (for example, in roof sheeting and cable production). Its widespread use is, however, impeded by the high investment costs. One way of avoiding these high costs is to arrange for the products to be irradiated by contractors. The optimum radiation dose for EPDM is determined by the required pattern of properties. From this study it may be concluded that the network is primarily built up at a radiation dose of up to approximately 100 kGy. The degree to which it is built up depends partly on the coactivator used and the EPDM type used. In choosing the coactivator, allowance has to be made for its solubility in EPDM. The type of oil chosen and any stabilizer additions will affect the crosslinking efficiency. Contrary to studies published earlier, in this study it was found that when EDMA is used as a coactivator, no difference can be detected between a DCPD type (4%) and an ENB type (4%), provided both have an identical molecular weight distribution. Increasing the ENB content has less effect on the final crosslink density than using a type having a broader molecular weight distribution

  18. Dielectric Cure Monitoring of Thermosetting Matrix Composites

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyoung Geun [Agency for Defense Development, Daejeon (Korea, Republic of); Lee, Dae Gil [KAIST, Daejeon (Korea, Republic of)

    2003-10-15

    Cure monitoring can be used to improve the quality and productivity of thermosetting resin matrix composite products during their manufacturing process. In this work, the sensitivity of dielectrometry was improved by adequate separation the efforts of sensor and externals on the measured signal. A new algorithm to obtain the degree of cure during dielectric cure monitoring of glass/polyester and glass/epoxy composites was developed by employing a function of both temperature and dissipation factor, in which five cure monitoring parameters were used to calculate the degree of cure. The decreasing pattern of dissipation factor was compared with the relationships between the degree of cure and the resin viscosity. The developed algorithm might be employed for the in situ cure monitoring of thermosetting resin composites

  19. Dielectric Cure Monitoring of Thermosetting Matrix Composites

    International Nuclear Information System (INIS)

    Kim, Hyoung Geun; Lee, Dae Gil

    2003-01-01

    Cure monitoring can be used to improve the quality and productivity of thermosetting resin matrix composite products during their manufacturing process. In this work, the sensitivity of dielectrometry was improved by adequate separation the efforts of sensor and externals on the measured signal. A new algorithm to obtain the degree of cure during dielectric cure monitoring of glass/polyester and glass/epoxy composites was developed by employing a function of both temperature and dissipation factor, in which five cure monitoring parameters were used to calculate the degree of cure. The decreasing pattern of dissipation factor was compared with the relationships between the degree of cure and the resin viscosity. The developed algorithm might be employed for the in situ cure monitoring of thermosetting resin composites

  20. The electron beam cure of epoxy paste adhesives

    International Nuclear Information System (INIS)

    Farmer, J.D.; Janke, C.J.; Lopata, V.J.

    1998-01-01

    Recently developed epoxy paste adhesives were electron beam cured and experimentally explored to determine their suitability for use in an aerospace-quality aircraft component. There were two major goals for this program. The first was to determine whether the electron beam-curable past adhesives were capable of meeting the requirements of the US Air Force T-38 supersonic jet trainer composite windshield frame. The T-38 windshield frame's arch is currently manufactured by bonding thin stainless steel plies using an aerospace-grade thermally-cured epoxy film adhesive. The second goal was to develop the lowest cost hand layup and debulk process that could be used to produce laminated steel plies with acceptable properties. The laminate properties examined to determine adhesive suitability include laminate mechanical and physical properties at room, adhesive tack, out-time capability, and the debulk requirements needed to achieve these properties. Eighteen past adhesives and four scrim cloths were experimentally examined using this criteria. One paste adhesive was found to have suitable characteristics in each of these categories and was later chosen for the manufacture of the T-38 windshield frame. This experimental study shows that by using low-cost debulk and layup processes, the electron beam-cured past adhesive mechanical and physical properties meet the specifications of the T-38 composite windshield frame

  1. Electron Beam curing of intaglio inks

    International Nuclear Information System (INIS)

    O'Brien, T.

    1984-01-01

    Press trials conducted by the US Bureau of Engraving and Printing at the National Bank of Denmark in September 8-21, 1982, clearly indicated the feasibility of Electron Beam (EB) curing for web intaglio printing. These trials, some at continuous press runs of up to six hours, gave positive results for virtually all our requirements including: print quality, press speeds, ability to print both sides of the web on one pass through a press, acceptable ink curing at one megarad or less, and minimum substrate deterioration or loss of moisture. In addition, these trials demonstrated many advantages over thermal curing which is the only other alternative to two sided printing in one pass through the press. These advantages can be found in product quality, a cleaner environment, and in economics. This development program is still in progress with efforts now directed towards adapting EB ink technology to the latest developments in intaglio printing, i.e. aqueous cylinder wiping which requires EB inks to be water dispersable. Also the stability of materials in contact with EB inks is being investigated

  2. Electron beam curing of intaglio inks

    International Nuclear Information System (INIS)

    O'Brien, T.

    1985-01-01

    Press trials conducted by the U.S. Bureau of Engraving and Printing at the National Bank of Denmark clearly indicated the feasibility of Electron Beam (E.B.) curing for web intaglio printing . These trials, some at continuous press runs of up to six hours, gave positive results for virtually all our requirements including: print quality, press speeds, ability to print both sides of the web on one pass through a press, acceptable ink curing at one megarad or less, and minimum substrate deterioration or loss of moisture. In addition, these trials demonstrated many advantages over thermal curing which is the only other alternative to two sided printing in one pass through the press. These advantages can be found in product quality, a cleaner environment, and in economics. This development program is still in progress with efforts now directed towards adapting E.B. ink technology to the latest developments in intaglio printing, i.e. aqueous cylinder wiping which requires E.B. inks to be water dispersable. Also the stability of materials in contact with E.B. inks is being investigated. (author)

  3. Composite cements benefit from light-curing.

    Science.gov (United States)

    Lührs, Anne-Katrin; De Munck, Jan; Geurtsen, Werner; Van Meerbeek, Bart

    2014-03-01

    To investigate the effect of curing of composite cements and a new ceramic silanization pre-treatment on the micro-tensile bond strength (μTBS). Feldspathic ceramic blocks were luted onto dentin using either Optibond XTR/Nexus 3 (XTR/NX3; Kerr), the silane-incorporated 'universal' adhesive Scotchbond Universal/RelyX Ultimate (SBU/RXU; 3M ESPE), or ED Primer II/Panavia F2.0 (ED/PAF; Kuraray Noritake). Besides 'composite cement', experimental variables were 'curing mode' ('AA': complete auto-cure at 21°C; 'AA*': complete auto-cure at 37°C; 'LA': light-curing of adhesive and auto-cure of cement; 'LL': complete light-curing) and 'ceramic surface pre-treatment' ('HF/S/HB': hydrofluoric acid ('HF': IPS Ceramic Etching Gel, Ivoclar-Vivadent), silanization ('S': Monobond Plus, Ivoclar-Vivadent) and application of an adhesive resin ('HB': Heliobond, Ivoclar-Vivadent); 'HF/SBU': 'HF' and application of the 'universal' adhesive Scotchbond Universal ('SBU'; 3M ESPE, only for SBU/RXU)). After water storage (7 days at 37°C), ceramic-dentin sticks were subjected to μTBS testing. Regarding the 'composite cement', the significantly lowest μTBSs were measured for ED/PAF. Regarding 'curing mode', the significantly highest μTBS was recorded when at least the adhesive was light-cured ('LA' and 'LL'). Complete auto-cure ('AA') revealed the significantly lowest μTBS. The higher auto-curing temperature ('AA*') increased the μTBS only for ED/PAF. Regarding 'ceramic surface pre-treatment', only for 'LA' the μTBS was significantly higher for 'HF/S/HB' than for 'HF/SBU'. Complete auto-cure led to inferior μTBS than when either the adhesive (on dentin) or both adhesive and composite cement were light-cured. The use of a silane-incorporated adhesive did not decrease luting effectiveness when also the composite cement was light-cured. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  4. Electron beam curing — taking good ideas to the manufacturing floor

    Science.gov (United States)

    Saunders, C.; Lopata, V.; Barnard, J.; Stepanik, T.

    2000-03-01

    Acsion is exploiting several emerging electron beam EB applications ranging from composite curing and repair to viscose manufacturing. EB curing of composite structures offers several advantages: significantly reduced curing times; improvements in part quality and performance; reduced environmental and health concerns; improvements in material handling; and reduced overall manufacturing costs compared to thermal curing. The aerospace industry is developing EB technology in all of their market sectors, including military aviation and space products. Some specific products include cryogenic fuel tanks, improved canopy frames for jet aircraft, and the all-composite military aircraft. This paper discusses each of these opportunities.

  5. Electron Beam Curing of Coil Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Morganstern, K. H. [Radiation Dynamics, Inc., Westbury, NY (United States)

    1969-12-15

    The application of electron accelerators for the rapid curing of coatings on coil processing of steel and aluminium appears to have many practical and economic advantages. This paper discusses this particular application, but in the general framework of electron beam application by industry. Although industry has investigated radiation application for two decades, there have been few applications to date. The reasons for this are discussed as well as the shift in attitude now taking place, indicating a more ready acceptance of radiation processing by industry. This shift is apparent particularly in the coatings field, where the benefits of radiation processing are quite evident. In order to pinpoint these benefits a specific coatings application - coil coating - has been chosen. A typical conventional coil coating line is discussed and compared to a line employing a radiation source. Specific engineering information on the types of electron accelerators suitable for this application; the relative economics of radiation vs. heat curing; and a number of other peripheral advantages of radiation are discussed. (author)

  6. Electron beam curing of acrylic oligomers

    International Nuclear Information System (INIS)

    Seto, J.; Arakawa, S.; Ishimoto, C.; Miyashita, M.; Nagai, T.; Noguchi, T.; Shibata, A.

    1984-01-01

    The electron-beam curing process of acrylic oligomers, with and without γ-Fe 2 O 3 pigment filler and blended linear polymer, was investigated in terms of molecular structure and reaction mechanism. The polymerized fraction of trimethylolpropane-triacrylate (TMPTA) oligomers increases with increasing total dose, and is independent of the dose rate. Since the reaction rate is linearly dependent on the dose rate, the reaction mechanism involves monomolecular termination. The reaction rate does not depend on the number of functional groups of the oligomer at low doses, but above 0.3 Mrad the rate is slower for oligomers of higher functionality. A gel is formed more readily upon curing of a polyfunctional than a monofunctional oligomer, especially at high conversion to polymer; the resulting loss of flexibility of the polymer chains slows the reaction. Decrease of the molecular weight per functional group results in lower conversion; this is also due to the loss of chain flexibility, which is indicated as well by a higher glass-transition temperature. Modification of the acrylate oligomers with urethane results in more effective cross-linking reactions because of the more rigid molecular chains. Addition of γ-Fe 2 O 3 pigment reduces the reaction rate very little, but has the effect of providing added structural integrity, as indicated by the decrease of solvent-extractable material and the improvement of anti-abrasion properties. However, the flexibility of the coating and its adhesion to a PET base film are diminished. To increase the flexibility, linear polyvinylchloride and/or polyurethane were added to the acrylic oligomers. Final conversion to polymer was nearly 100 percent, and a higher elastic modulus and better antiabrasion properties were realized

  7. Manufacturing prepainted steel sheet by electron beam curing

    International Nuclear Information System (INIS)

    Oka, Joji

    1987-01-01

    Several advantages are offered by electron beam curing. A formidably hard and stain resistant paint film which is difficult to obtain by heat curing paint is developed. As a result, a unique new prepainted steel is produced. Four technologies are involved: development high-quality paint, selection of optimum electron beam processor, technology to control electron beam processing atmosphere and secondary X-ray shield technology. These technologies are described in detail. (A.J.)

  8. Application of thiolterminated prepolymers for electron beam curing coating system

    International Nuclear Information System (INIS)

    Seko, Kenji; Isozaki, Osamu; Iwasawa, Naozumi

    1988-01-01

    It has been known that the mixture of an unsaturated prepolymer and a thiolated prepolymer can be cured by the relatively low dose of electron beam irradiation. As a thiolated prepolymer, polyether-polythiol prepolymer has been in the market. However, the coating films derived from the composition comprising the thiolated prepolymer do not have enough mechanical strength for practical use. In this study, the synthesis of thiolterminated urethane prepolymer and the coating composition comprising this prepolymer for obtaining the coating films having good mechanical properties were investigated. The raw materials used for the synthesis of thiolterminated urethane prepolymer are shown. Its synthesis and the measurement of thiol content, coating formation, the electron beam curing of the coatings and the testing method of coated film performance are explained. The results of the synthesis of the thiolterminated urethane prepolymer, the thermal stability, curability, physical properties and adhesion strength of the coatings are reported. The coatings can be applied to steel and PVC films, and used as the adhesive for steel-PVC film laminates. (Kako, I.)

  9. Cure Behavior and Thermal Properties of Diepoxidized Cardanol Resin Cured by Electron Beam Process

    International Nuclear Information System (INIS)

    Cho, Donghwan; Cheon, Jinsil

    2013-01-01

    Thermal curing of epoxy resin requires high temperature, time-consuming process and the volatilization of hardener. It has known that electron beam curing of epoxy resin is a fast process and occurs at low or room temperature that help reduce residual mechanical stresses in thermosetting polymers. Diepoxidized cardanol (DEC) can be synthesized by an enzymatic method from cashew nut shell liquid (CNSL), that constitutes nearly one-third of the total nut weight. A large amount of CNSL can be formed as a byproduct of the mechanical processes used to render the cashew kerneledible and its total production approaches one million tons annually, which can be bio-degradable and replace the industrial thermosetting plastics. It is expected that DEC may be cured as in an epoxy resin, which was constituted on two epoxide group and long alkyl chain, and two-types of onium salts (cationic initiator) were used as a photo-initiator. The experimental variables of this study are type and concentration of photo-initiators and electron beam dosage. In this study, the effects of initiator type and concentration on the cure behavior and the thermal properties of DEC resin processed by using electron beam technology were studied using FT-IR, TGA, TMA, DSC, and DMA. Figure 1 is the FT-IR results, showing the change of chemical structure of pure DEC and electron beam cured DEC. The characteristic absorption peak of epoxide group appeared at 850cm -1 . The shape and the height were reduced when the sample was irradiated with electron beam. From this result, the epoxide groups is DEC were opened by electron beam and cured. After then, electron beam cured DEC was investigated the effect of forming 3-dimensional network

  10. Cure Behavior and Thermal Properties of Diepoxidized Cardanol Resin Cured by Electron Beam Process

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Donghwan; Cheon, Jinsil [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

    2013-07-01

    Thermal curing of epoxy resin requires high temperature, time-consuming process and the volatilization of hardener. It has known that electron beam curing of epoxy resin is a fast process and occurs at low or room temperature that help reduce residual mechanical stresses in thermosetting polymers. Diepoxidized cardanol (DEC) can be synthesized by an enzymatic method from cashew nut shell liquid (CNSL), that constitutes nearly one-third of the total nut weight. A large amount of CNSL can be formed as a byproduct of the mechanical processes used to render the cashew kerneledible and its total production approaches one million tons annually, which can be bio-degradable and replace the industrial thermosetting plastics. It is expected that DEC may be cured as in an epoxy resin, which was constituted on two epoxide group and long alkyl chain, and two-types of onium salts (cationic initiator) were used as a photo-initiator. The experimental variables of this study are type and concentration of photo-initiators and electron beam dosage. In this study, the effects of initiator type and concentration on the cure behavior and the thermal properties of DEC resin processed by using electron beam technology were studied using FT-IR, TGA, TMA, DSC, and DMA. Figure 1 is the FT-IR results, showing the change of chemical structure of pure DEC and electron beam cured DEC. The characteristic absorption peak of epoxide group appeared at 850cm{sup -1}. The shape and the height were reduced when the sample was irradiated with electron beam. From this result, the epoxide groups is DEC were opened by electron beam and cured. After then, electron beam cured DEC was investigated the effect of forming 3-dimensional network.

  11. Out-of-Autoclave Cure Composites

    Science.gov (United States)

    Hayes, Brian S.

    2015-01-01

    As the size of aerospace composite parts exceeds that of even the largest autoclaves, the development of new out-of-autoclave processes and materials is necessary to ensure quality and performance. Many out-of-autoclave prepreg systems can produce high-quality composites initially; however, due to long layup times, the resin advancement commonly causes high void content and variations in fiber volume. Applied Poleramic, Inc. (API), developed an aerospace-grade benzoxazine matrix composite prepreg material that offers more than a year out-time at ambient conditions and provides exceptionally low void content when out-of-autoclave cured. When compared with aerospace epoxy prepreg systems, API's innovation offers significant improvements in terms of out-time at ambient temperature and the corresponding tack retention. The carbon fiber composites developed with the optimized matrix technology have significantly better mechanical performance in terms of hot-wet retention and compression when compared with aerospace epoxy matrices. These composites also offer an excellent overall balance of properties. This matrix system imparts very low cure shrinkage, low coefficient of thermal expansion, and low density when compared with most aerospace epoxy prepreg materials.

  12. Modeling the curing process of thermosetting resin matrix composites

    Science.gov (United States)

    Loos, A. C.

    1986-01-01

    A model is presented for simulating the curing process of a thermosetting resin matrix composite. The model relates the cure temperature, the cure pressure, and the properties of the prepreg to the thermal, chemical, and rheological processes occurring in the composite during cure. The results calculated with the computer code developed on the basis of the model were compared with the experimental data obtained from autoclave-curved composite laminates. Good agreement between the two sets of results was obtained.

  13. Study on the heat-resistant EB curing composites

    International Nuclear Information System (INIS)

    Bao Jianwen; Li Yang; Li Fengmei

    2000-01-01

    There are many advantages in the EB-curing process of composites. Heat-resistant EB-curing composites could substitute for polyimide composites used in aeronautical engine. The effects of catalyst and dose on the cured resin were investigated. The heat-resistance of the resin cured by EB was evaluated by dynamic mechanical thermal analysis (DMTA). The experiment result shows that the mechanical property of the composites cured by EB could meet the needs of the aeronautical engine in 250degC. (author)

  14. Curing agent for polyepoxides and epoxy resins and composites cured therewith. [preventing carbon fiber release

    Science.gov (United States)

    Serafini, T. T.; Delvigs, P.; Vannucci, R. D. (Inventor)

    1981-01-01

    A curing for a polyepoxide is described which contains a divalent aryl radical such as phenylene a tetravalent aryl radical such as a tetravalent benzene radical. An epoxide is cured by admixture with the curing agent. The cured epoxy product retains the usual properties of cured epoxides and, in addition, has a higher char residue after burning, on the order of 45% by weight. The higher char residue is of value in preventing release to the atmosphere of carbon fibers from carbon fiber-epoxy resin composites in the event of burning of the composite.

  15. CURING OF POLYMERIC COMPOSITES USING MICROWAVE RESIN TRANSFER MOULDING (RTM

    Directory of Open Access Journals (Sweden)

    R. YUSOFF

    2007-08-01

    Full Text Available The main objective of this work is to compare the difference between microwave heating and conventional thermal heating in fabricating carbon/epoxy composites. Two types of epoxy resin systems were used as matrices, LY5052-HY5052 and DGEBA-HY917-DY073. All composite samples were fabricated using resin transfer moulding (RTM technique. The curing of the LY5052-HY5052-carbon and the DGEBA-HY917-DY073-carbon composite systems, were carried out at 100 °C and 120 °C, respectively. Microwave heating showed better temperature control than conventional heating, however, the heating rate of the microwave cured samples were slower than the conventionally cured samples. This was attributed to the lower power (250 W used when heating with microwaves compared to 2000 W used in conventional heating. Study of thermal characteristics as curing progressed showed that the polymerisation reaction occurred at a faster rate during microwave curing than in conventional curing for both the DGEBA and the LY/HY5052 carbon composite systems. The actual cure cycle was reduced from 60 minutes to 40 minutes when using microwaves for curing DGEBA-carbon composites. As for LY/HY5052-carbon composites, the actual cure cycle was reduced from 3 hours to 40 minutes. Both conventional and microwave heating yielded similar glass transition temperatures (120 °C for DGEBA systems and 130 °C for LY/HY5052 systems. Microwave cured composites had higher void contents than conventionally cured composites (2.2-2.8% and 1.8-2.4% for DGEBA and LY/HY5052 microwave cured composites, respectively, compared to 0.2-0.4% for both DGEBA and LY/HY5052 thermally cured composites. C-scan traces showed that all composites, regardless of methods of curing, had minimal defects.

  16. Stratospheric experiments on curing of composite materials

    Science.gov (United States)

    Chudinov, Viacheslav; Kondyurin, Alexey; Svistkov, Alexander L.; Efremov, Denis; Demin, Anton; Terpugov, Viktor; Rusakov, Sergey

    2016-07-01

    Future space exploration requires a large light-weight structure for habitats, greenhouses, space bases, space factories and other constructions. A new approach enabling large-size constructions in space relies on the use of the technology of polymerization of fiber-filled composites with a curable polymer matrix applied in the free space environment on Erath orbit. In orbit, the material is exposed to high vacuum, dramatic temperature changes, plasma of free space due to cosmic rays, sun irradiation and atomic oxygen (in low Earth orbit), micrometeorite fluence, electric charging and microgravitation. The development of appropriate polymer matrix composites requires an understanding of the chemical processes of polymer matrix curing under the specific free space conditions to be encountered. The goal of the stratospheric flight experiment is an investigation of the effect of the stratospheric conditions on the uncured polymer matrix of the composite material. The unique combination of low residual pressure, high intensity UV radiation including short-wave UV component, cosmic rays and other aspects associated with solar irradiation strongly influences the chemical processes in polymeric materials. We have done the stratospheric flight experiments with uncured composites (prepreg). A balloon with payload equipped with heater, temperature/pressure/irradiation sensors, microprocessor, carrying the samples of uncured prepreg has been launched to stratosphere of 25-30 km altitude. After the flight, the samples have been tested with FTIR, gel-fraction, tensile test and DMA. The effect of cosmic radiation has been observed. The composite was successfully cured during the stratospheric flight. The study was supported by RFBR grants 12-08-00970 and 14-08-96011.

  17. An emerging alternative to thermal curing: Electron curing of fiber-reinforced composites

    International Nuclear Information System (INIS)

    Singh, A.; Saunders, C.B.; Lopata, V.J.; Kremers, W.; Chung, M.

    1995-01-01

    Electron curing of fiber-reinforced composites to produce materials with good mechanical properties has been demonstrated by the authors' work, and by Aerospatiale. The attractions of this technology are the technical and processing advantages offered over thermal curing, and the projected cost benefits. Though the work so far has focused on the higher value composites for the aircraft and aerospace industries, the technology can also be used to produce composites for the higher volume industries, such as transportation and automotive

  18. Electron beam curing polyurethane acrylate oligomer in air

    International Nuclear Information System (INIS)

    Zhu, Zhenkang; Chen, Xing; Zhou, Jichun; Ma, Zue-Teh

    1988-01-01

    It has been found according to our synthesis that a novel kind of polyurethane acrylate oligomer can be cured by electron beam in the presence of oxygen, even at normal atomospheric levels, without any additives. Irradiation of the oligomer with substantially complete cure to a solid non-tacky state is quite remarkable. It has the same gel content (90 %) in air as in nitrogen at dose of 33 kGy. Double bond conversion of the oligomer is about 50 % by I.R. (author)

  19. EVALUATION OF DIELECTRIC CURING MONITORING INVESTIGATING LIGHT-CURING DENTAL FILLING COMPOSITES

    Directory of Open Access Journals (Sweden)

    Johannes Steinhaus

    2011-05-01

    Full Text Available The aim of this study is the evaluation of a dielectric analysis (DEA method monitoring the curing behaviour of a light curing dental filling material in real-time. The evaluation is to extract the influence of light intensity on the photo-curing process of dental composite filling materials. The intensity change is obtained by measuring the curing process at different sample depth. It could be shown that increasing sample thickness, and therefore exponentially decreasing light intensity, causes a proportional decrease in the initial curing rate. Nevertheless, the results give rise to the assumption that lower illumination intensities over a long period cause higher overall conversion, and thus better mechanical properties. This would allow for predictions of the impact of different curing-rates on the final mechanical properties.

  20. Microporous polyurethane-acrylamide film cured by electron beam irradiation

    International Nuclear Information System (INIS)

    Ando, Masayuki; Goto, Takakazu; Tsuchiya, Mitsuru; Uryu, Toshiyuki

    1988-01-01

    The morphology and aggregation structure of electron beam (EB)-cured microporous polyurethane-acrylamide film was investigated. The urethane-acrylamide prepolymer was synthesized by the reaction of poly(butylene adipate)diol, diphenylmethane diisocyanate, and N-(hydroxymethyl)acrylamide. It was found from scanning electron microscopy that the urethane-acrylamide film, which was prepared by using a methyl ethyl ketone and dimethylformamide (3:1 v/v) mixture as casting solvent, had a microporous structure with pore size of several micrometers, and that the morphology was fixed by EB irradiation. The pore volume of the EB-cured microporous film was determined to be about 460 mm 3 g -1 by mercury porosimetry. The micropores were not destroyed even after immersing in solvent, possibly because the cured film had high crystallinity and dense crosslinking. Moreover, it was found by X-ray photelectron spectroscopy that terminal portions of urethane-acrylamide were localized at the film surface. (author)

  1. Application of electron beam curing technology for paper products

    International Nuclear Information System (INIS)

    Takaharu Miura

    1999-01-01

    The electron beam (EB) curing technology has rapidly advanced in recent years. However there were few examples applying this technology to paper products. One reason comes from the high price of EB equipment and the other comes from the difficulty of controlling the irradiation which gives damages to paper. In spite of these problems, the EB cured coating layer shows remarkable features, such as solvent-resistance, water-resistance, heat-resistance and high smoothness using the drum casting technique. Concentrating on application of this technology to paper, we have already developed some products. For example, paper for printings (Super Mirror PN) and for white boards (Super Mirror WB) have been manufactured. In this presentation, we are going to introduce this EB curing technique and the products

  2. Curing kinetics of visible light curing dental resin composites investigated by dielectric analysis (DEA).

    Science.gov (United States)

    Steinhaus, Johannes; Hausnerova, Berenika; Haenel, Thomas; Großgarten, Mandy; Möginger, Bernhard

    2014-03-01

    During the curing process of light curing dental composites the mobility of molecules and molecule segments is reduced leading to a significant increase of the viscosity as well as the ion viscosity. Thus, the kinetics of the curing behavior of 6 different composites was derived from dielectric analysis (DEA) using especially redesigned flat sensors with interdigit comb electrodes allowing for irradiation at the top side and measuring the ion viscosity at the bottom side. As the ion viscosities of dental composites change 1-3 orders of magnitude during the curing process, DEA provides a sensitive approach to evaluate their curing behavior, especially in the phase of undisturbed chain growth. In order to determine quantitative kinetic parameters a kinetic model is presented and examined for the evaluation of the ion viscosity curves. From the obtained results it is seen that DEA might be employed in the investigation of the primary curing process, the quality assurance of ingredients as well as the control of processing stability of the light curing dental composites. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. Curing of Thick Thermoset Composite Laminates: Multiphysics Modeling and Experiments

    Science.gov (United States)

    Anandan, S.; Dhaliwal, G. S.; Huo, Z.; Chandrashekhara, K.; Apetre, N.; Iyyer, N.

    2017-11-01

    Fiber reinforced polymer composites are used in high-performance aerospace applications as they are resistant to fatigue, corrosion free and possess high specific strength. The mechanical properties of these composite components depend on the degree of cure and residual stresses developed during the curing process. While these parameters are difficult to determine experimentally in large and complex parts, they can be simulated using numerical models in a cost-effective manner. These simulations can be used to develop cure cycles and change processing parameters to obtain high-quality parts. In the current work, a numerical model was built in Comsol MultiPhysics to simulate the cure behavior of a carbon/epoxy prepreg system (IM7/Cycom 5320-1). A thermal spike was observed in thick laminates when the recommended cure cycle was used. The cure cycle was modified to reduce the thermal spike and maintain the degree of cure at the laminate center. A parametric study was performed to evaluate the effect of air flow in the oven, post cure cycles and cure temperatures on the thermal spike and the resultant degree of cure in the laminate.

  4. Application of electron beam curing in web-offset printing

    International Nuclear Information System (INIS)

    Rodrigues, A.M.; Newcomb, W.T.

    1984-01-01

    Four years ago, the first commercial installation of an electron beam processor, coupled with a high speed web offset printing press was described. This line has been in operation since and its success demonstrates the advantages and feasibility of such an application. Just recently, another company has announced that it is using electron beam curing in its printing lines. Judging from the amount of inquiries and opportunities being actively pursued one can state that the use of electron beam systems in printing applications has come of age. This paper describes the advantages of this process, the characteristics of the equipment that are important for industrial use in a multishift environment, and addresses its economics through analysis of some major cost elements

  5. Coherent instabilities of proton beams in accelerators and storage rings - experimental results, diagnosis and cures

    International Nuclear Information System (INIS)

    Schnell, W.

    1977-01-01

    The author discusses diagnosis and cure of proton beam instabilities in accelerators and storage rings. Coasting beams and bunched beams are treated separately and both transverse and longitudinal instabilities are considered. (B.D.)

  6. Depth of cure of bulk-fill flowable composite resins.

    Science.gov (United States)

    Pedalino, Inaam; Hartup, Grant R; Vandewalle, Kraig S

    2015-01-01

    In recent years, manufacturers have introduced flowable composite resins that reportedly can be placed in increments of 4 mm or greater. The purpose of this study was to evaluate the depth of cure of bulk-fill flowable composite resins (SureFil SDR Flow, Grandio Flow, and Venus Bulk Fill) and a conventional flowable composite resin (Revolution Formula 2). Depth of cure was measured in terms of bottom-maximum Knoop hardness number (KHN) ratios and the International Organization for Standardization (ISO) 4049 scrape technique. Shades A2 and A3 of SureFil SDR Flow, Grandio Flow, and Revolution Formula 2 were tested. Venus Bulk Fill was tested in its only available shade (universal). Specimens in thicknesses of 2, 3, 4, 5, and 6 mm were polymerized for 20 or 40 seconds, and a hardness tester was used to determine the hardness ratios for each shade at each thickness. For the scraping technique, after specimens were exposed to the curing light, unpolymerized composite resin was removed with a plastic instrument, the polymerized composite was measured, and the length was divided by 2 per ISO guidelines. According to the KHN ratios and the scrape test, Venus Bulk Fill predictably exceeded the manufacturer's claim of a 4-mm depth of cure at both 20 and 40 seconds of curing time. The overall results for depth of cure showed that Venus Bulk Fill ≥ SureFil SDR Flow ≥ Grandio Flow ≥ Revolution Formula 2.

  7. Influence of curing time, overlay material and thickness on three light-curing composites used for luting indirect composite restorations.

    Science.gov (United States)

    D'Arcangelo, Camillo; De Angelis, Francesco; Vadini, Mirco; Carluccio, Fabio; Vitalone, Laura Merla; D'Amario, Maurizio

    2012-08-01

    To assess the microhardness of three resin composites employed in the adhesive luting of indirect composite restorations and examine the influence of the overlay material and thickness as well as the curing time on polymerization rate. Three commercially available resin composites were selected: Enamel Plus HRI (Micerium) (ENA), Saremco ELS (Saremco Dental) (SAR), Esthet-X HD (Dentsply/DeTrey) (EST-X). Post-polymerized cylinders of 6 different thicknesses were produced and used as overlays: 2 mm, 3 mm, 3.5 mm, 4 mm, 5 mm, and 6 mm. Two-mm-thick disks were produced and employed as underlays. A standardized amount of composite paste was placed between the underlay and the overlay surfaces which were maintained at a fixed distance of 0.5 mm. Light curing of the luting composite layer was performed through the overlays for 40, 80, or 120 s. For each specimen, the composite to be cured, the cured overlay, and the underlay were made out of the same batch of resin composite. All specimens were assigned to three experimental groups on the basis of the resin composite used, and to subgroups on the basis of the overlay thickness and the curing time, resulting in 54 experimental subgroups (n = 5). Forty-five additional specimens, 15 for each material under investigation, were produced and subjected to 40, 80, or 120 s of light curing using a microscope glass as an overlay; they were assigned to 9 control subgroups (n = 5). Three Vicker's hardness (VH) indentations were performed on each specimen. Means and standard deviations were calculated. Data were statistically analyzed using 3-way ANOVA. Within the same material, VH values lower than 55% of control were not considered acceptable. The used material, the overlay thickness, and the curing time significantly influenced VH values. In the ENA group, acceptable hardness values were achieved with 3.5-mm or thinner overlays after 120 or 80 s curing time (VH 41.75 and 39.32, respectively), and with 2-mm overlays after 40 s (VH 54

  8. Cure and mechanical behaviors of cycloaliphatic/DGEBA epoxy blend system using electron-beam technique

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.R.; Heo, G.Y.; Park, S.J. [Korea Research Institute of Chemical Technology, Taejeon (Korea)

    2002-05-01

    4-Vinyl-1- cyclohexene diepoxide (VCE)/ diglycidyl ether of bisphenol -A(DGEBA) epoxy blends with benzylquinoxalinium hexafluoroanti-monate were cured using an electron-beam technique. the effect of DGEBA content to VCE on cure behavior, thermal stabilities, and mechanical properties was investigated. The composition of VCE/DGEBA blend system varied within 100:0, 80:20, 60:40. 40:60 20:80, and 0:100wt%. The cure behavior and thermal stability of the cured specimens was monited by near-infrared spectroscopy and thermogravimetric analysis, respectively. Also, the critical stress intensity factor (K{sub 1C}) test of the cured specimens was performed to study the mechanical interfacial properties. As a result, the decreases of short side-chide structure and chain scission were observed in NIR measurements as the DGEBA content increases, resulting in varying the hydroxyl and carbonyl groups. And, the initial decomposition temperature (IDT), temperature of maximum weight loss (T{sub max}), and decomposition activation energy (E{sub d}) as thermal stability factors were increased with increasing the DGEBA content. These results could be explained by mean of decreasing viscosity, stable aromatic ring structure, and grafted interpenetrating polymer network with increasing of DGEBA content. Also, the maximum K{sub 1C} value showed at mixing ratio of 40:60 wt% in this blend system. (author). 22 refs., 2 tabs., 6 figs.

  9. Post-cure depth of cure of bulk fill dental resin-composites.

    Science.gov (United States)

    Alrahlah, A; Silikas, N; Watts, D C

    2014-02-01

    To determine the post-cure depth of cure of bulk fill resin composites through using Vickers hardness profiles (VHN). Five bulk fill composite materials were examined: Tetric EvoCeram(®) Bulk Fill, X-tra base, Venus(®) Bulk Fill, Filtek™ Bulk Fill, SonicFill™. Three specimens of each material type were prepared in stainless steel molds which contained a slot of dimensions (15 mm × 4 mm × 2 mm), and a top plate. The molds were irradiated from one end. All specimens were stored at 37°C for 24h, before measurement. The Vickers hardness was measured as a function of depth of material, at 0.3mm intervals. Data were analysed by one-way ANOVA using Tukey post hoc tests (α=0.05). The maximum VHN ranged from 37.8 to 77.4, whilst the VHN at 80% of max.VHN ranged from 30.4 to 61.9. The depth corresponding to 80% of max.VHN, ranged from 4.14 to 5.03 mm. One-way ANOVA showed statistically significant differences between materials for all parameters tested. SonicFill exhibited the highest VHN (pFill the lowest (p≤0.001). SonicFill and Tetric EvoCeram Bulk Fill had the greatest depth of cure (5.03 and 4.47 mm, respectively) and was significant's different from X-tra base, Venus Bulk Fill and Filtek Bulk Fill (p≤0.016). Linear regression confirmed a positive regression between max.VHN and filler loading (r(2)=0.94). Bulk fill resin composites can be cured to an acceptable post-cure depth, according to the manufacturers' claims. SonicFill and Tetric EvoCeram Bulk Fill had the greatest depth of cure among the composites examined. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Ultraviolet and electron-beam curing of printing inks. January 1980-August 1987 (Citations from World Surface Coatings Abstracts). Report for January 1980-August 1987

    International Nuclear Information System (INIS)

    1989-08-01

    This bibliography contains citations concerning methods, techniques, and applications for the ultraviolet and electron-beam curing of printing inks. Topics include ink compositions, curing methods and equipment, cured-ink evaluations, screen printing inks, photoinitiators, and ink binders. The pollution and safety problems, and future trends of UV- and E-beam-cured printing inks are considered. Applications in screen printing on polyethylene or polypropylene bottles, and decorative printing of glass are also examined. (This updated bibliography contains 237 citations, 63 of which are new entries to the previous edition.)

  11. Radiation cured polyester compositions containing metal-properties

    Science.gov (United States)

    Szalińska, H.; Pietrzak, M.; Gonerski, A.

    The subject of the studies was unsaturated polyester resin, Polimal-109 and its compositions containing acrylates of: sodium, potassium, calcium, magnesium, barium, manganese, iron, cobalt, copper and acrylic acid. Polyester resin modified with acrylic acid salts was cured with 60Co gamma radiation. Measurements of Vicat softening temperature, water absorption, creep current resistance, volume and surface resistivity, the tangent of dielectric loss angle and permittivity of radiation cured compositions were carried out. The results of the studies presented testify to the fact that the properties of cross-linked polymers alter after ionogenic compounds have been introduced into them.

  12. Radiation cured polyester compositions containing metal-properties

    International Nuclear Information System (INIS)

    Szalinska, H.; Pietrzak, M.; Gonerski, A.

    1987-01-01

    The subject of the studies was unsaturated polyester resin, Polimal-109 and its compositions containing acrylates of: sodium, potassium, calcium, magnesium, barium, manganese, iron, cobalt, copper and acrylic acid. Polyester resin modified with acrylic acid salts was cured with 60 Co gamma radiation. Measurements of Vicat softening temperature, water absorption, creep current resistance, volume and surface resistivity, the tangent of dielectric loss angle and permittivity of radiation cured compositions were carried out. The results of the studies presented testify to the fact that the properties of cross-linked polymers alter after ionogenic compounds have been introduced into them. (author)

  13. Temperature and curing time affect composite sorption and solubility

    Directory of Open Access Journals (Sweden)

    Fabrício Luscino Alves de Castro

    2013-04-01

    Full Text Available Objective: This study evaluated the effect of temperature and curing time on composite sorption and solubility. Material and Methods: Seventy five specimens (8×2 mm were prepared using a commercial composite resin (ICE, SDI. Three temperatures (10°C, 25°C and 60°C and five curing times (5 s, 10 s, 20 s, 40 s and 60 s were evaluated. The specimens were weighed on an analytical balance three times: A: before storage (M1; B: 7 days after storage (M2; C: 7 days after storage plus 1 day of drying (M3. The storage solution consisted of 75% alcohol/25% water. Sorption and solubility were calculated using these three weights and specimen dimensions. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U Tests (α=5%. Results: The results showed that time, temperature and their interaction influenced the sorption and solubility of the composite (p0.05. The 60°C composite temperature led to lower values of sorption for all curing times when compared with the 10°C temperature (p0.05. Solubility was similar at 40 s and 60 s for all temperatures (p>0.05, but was higher at 10°C than at 60°C for all curing times (p0.05. Conclusions: In conclusion, higher temperatures or longer curing times led to lower sorption and solubility values for the composite tested; however, this trend was only significant in specific combinations of temperature and curing times.

  14. Effect of light dispersion of LED curing lights on resin composite polymerization.

    Science.gov (United States)

    Vandewalle, Kraig S; Roberts, Howard W; Andrus, Jeffrey L; Dunn, William J

    2005-01-01

    This study evaluated the effect of light dispersion of halogen and LED curing lights on resin composite polymerization. One halogen (Optilux 501, SDS/Kerr, Orange, CA, USA) and five light-emitting diode (LED) curing lights (SmartLite iQ, Dentsply Caulk, Milford, DE, USA; LEDemetron 1, SDS/Kerr; FLASHlite 1001, Discus Dental, Culver City, CA, USA; UltraLume LED 5, Ultradent Products, South Jordan, UT, USA; Allegro, Den-Mat, Santa Maria, CA, USA) were used in this study. Specimens (8 mm diameter by 2 mm thick) were made in polytetrafluoroethylene molds using hybrid (Z100, 3M ESPE, St. Paul, MN, USA) and microfill (A110, 3M ESPE) composite resins. The top surface was polymerized for 5 seconds with the curing light guide tip positioned at a distance of 1 and 5 mm. Degree of conversion (DC) of the composite specimens was analyzed on the bottom surface using micro-Fourier Transform Infrared (FTIR) spectroscopy (Perkin-Elmer FTIR Spectrometer, Wellesley, PA, USA) 10 minutes after light activation. DC at the bottom of the 2 mm specimen was expressed as a percentage of the mean maximum DC. Five specimens were created per curing light and composite type (n=5). Percent mean DC ratios and SDs were calculated for each light under each testing condition. Data were analyzed by analysis of variance (ANOVA)/Tukey's test (alpha = .05). A beam analyzer (LBA-700, Spiricon, Logan, UT, USA) was used to record the emitted light from the curing lights at 0 and 5 mm distances (n=5). A Top Hat factor was used to compare the quality of the emitted beam profile (LBA/PC, Spiricon). The divergence angle from vertical was also determined in the x- and y-axes (LBA/PC). Mean values and SDs were calculated for each light under each testing condition (0 and 5 mm, x- and y-axes) and analyzed by a two-way ANOVA/Tukey's test (alpha = .05). For DC ratios, significant differences were found based on curing light and curing distance (p < .05). At 1 mm, Optilux 501 and FLASHlite 1001 produced significantly

  15. Bulk-Fill Composites: Effectiveness of Cure With Poly- and Monowave Curing Lights and Modes.

    Science.gov (United States)

    Gan, J K; Yap, A U; Cheong, J W; Arista, N; Tan, Cbk

    This study compared the effectiveness of cure of bulk-fill composites using polywave light-emitting diode (LED; with various curing modes), monowave LED, and conventional halogen curing lights. The bulk-fill composites evaluated were Tetric N-Ceram bulk-fill (TNC), which contained a novel germanium photoinitiator (Ivocerin), and Smart Dentin Replacement (SDR). The composites were placed into black polyvinyl molds with cylindrical recesses of 4-mm height and 3-mm diameter and photopolymerized as follows: Bluephase N Polywave High (NH), 1200 mW/cm 2 (10 seconds); Bluephase N Polywave Low (NL), 650 mW/cm 2 (18.5 seconds); Bluephase N Polywave soft-start (NS), 0-650 mW/cm 2 (5 seconds) → 1200 mW/cm 2 (10 seconds); Bluephase N Monowave (NM), 800 mW/cm 2 (15 seconds); QHL75 (QH), 550 mW/cm 2 (21.8 seconds). Total energy output was fixed at 12,000 mJ/cm 2 for all lights/modes, with the exception of NS. The cured specimens were stored in a light-proof container at 37°C for 24 hours, and hardness (Knoop Hardness Number) of the top and bottom surfaces of the specimens was determined using a Knoop microhardness tester (n=6). Hardness data and bottom-to-top hardness ratios were subjected to statistical analysis using one-way analysis of variance/Scheffe's post hoc test at a significance level of 0.05. Hardness ratios ranged from 38.43% ± 5.19% to 49.25% ± 6.38% for TNC and 50.67% ± 1.54% to 67.62% ± 6.96% for SDR. For both bulk-fill composites, the highest hardness ratios were obtained with NM and lowest hardness ratios with NL. While no significant difference in hardness ratios was observed between curing lights/modes for TNC, the hardness ratio obtained with NM was significantly higher than the hardness ratio obtained for NL for SDR.

  16. Effect of curing mode on the hardness of dual-cured composite resin core build-up materials

    Directory of Open Access Journals (Sweden)

    César Augusto Galvão Arrais

    2010-06-01

    Full Text Available This study evaluated the Knoop Hardness (KHN values of two dual-cured composite resin core build-up materials and one resin cement exposed to different curing conditions. Two dual-cured core build-up composite resins (LuxaCore®-Dual, DMG; and FluoroCore®2, Dentsply Caulk, and one dual-cured resin cement (Rely X ARC, 3M ESPE were used in the present study. The composite materials were placed into a cylindrical matrix (2 mm in height and 3 mm in diameter, and the specimens thus produced were either light-activated for 40 s (Optilux 501, Demetron Kerr or were allowed to self-cure for 10 min in the dark (n = 5. All specimens were then stored in humidity at 37°C for 24 h in the dark and were subjected to KHN analysis. The results were submitted to 2-way ANOVA and Tukey's post-hoc test at a pre-set alpha of 5%. All the light-activated groups exhibited higher KHN values than the self-cured ones (p = 0.00001, regardless of product. Among the self-cured groups, both composite resin core build-up materials showed higher KHN values than the dual-cured resin cement (p = 0.00001. LuxaCore®-Dual exhibited higher KHN values than FluoroCore®2 (p = 0.00001 when they were allowed to self-cure, while no significant differences in KHN values were observed among the light-activated products. The results suggest that dual-cured composite resin core build-up materials may be more reliable than dual-cured resin cements when curing light is not available.

  17. Electron beam curing of dimer acid-based urethane acrylates for pressure sensitive adhesives

    International Nuclear Information System (INIS)

    Sasaki, Takashi; Takeda, Satoe; Shiraishi, Katsutoshi.

    1995-01-01

    Polyester urethane diacrylate prepolymers prepared from dimer acids (DUA) were cured with low energy electron beams to investigate adhesive properties of cured films. Among various type monomers added, monofunctional methacrylates such as isobornyl methacrylate (IBXMA) were effective for higher peel strength cured films although the dose-to-cure for the mixtures increased to 100 kGy or more. The increase in the molecular weight of prepolymers resulted in lower curing rates but higher peel strength. Aging tests up to 80degC for four weeks proved good stability in peel strength of the stored products. (author)

  18. Curing characteristics of flowable and sculptable bulk-fill composites

    OpenAIRE

    Miletic, Vesna; Pongpruenska, Pong; De Munck, Jan; Brooks, Neil R; Van Meerbeek, Bart

    2016-01-01

    OBJECTIVES: The aim of this study was to determine and correlate the degree of conversion (DC) with Vickers hardness (VH) and translucency parameter (TP) with the depth of cure (DoC) of five bulk-fill composites. MATERIALS AND METHODS: Six specimens per group, consisting of Tetric EvoCeram Bulk Fill ("TEC Bulk," Ivoclar Vivadent), SonicFill (Kerr), SDR Smart Dentin Replacement ("SDR," Dentsply), Xenius base ("Xenius," StickTech; commercialized as EverX Posterior, GC), Filtek Bul...

  19. Microhardness of resin composite materials light-cured through fiber reinforced composite.

    NARCIS (Netherlands)

    Fennis, W.M.M.; Ray, N.J.; Creugers, N.H.J.; Kreulen, C.M.

    2009-01-01

    OBJECTIVES: To compare polymerization efficiency of resin composite basing materials when light-cured through resin composite and fiber reinforced composite (FRC) by testing microhardness. METHODS: Simulated indirect restorations were prepared by application of resin composite (Clearfil AP-X) or FRC

  20. Electron-beam curing of paints and varnishes on wood panels

    International Nuclear Information System (INIS)

    Grosmaire, P.R.

    1977-01-01

    An analysis is presented of the relative costs of curing polyester coated wood panels using (a) the conventional peroxide cure, (b) treatment with UV light, or (c) electron beams. Electron treatment is shown to compare very favourably with either of the other treatments. (U.K.)

  1. Improvement of the fracture toughness matrix cured by electron beam radiation, by incorporation of thermoplastic

    International Nuclear Information System (INIS)

    Chauray, E.

    2003-07-01

    The aim of the present study is to improve the fracture toughness of a vinyl-ester matrix cured by electron beam radiation, by incorporation of a thermoplastic polymer. The ultimate plan is to improve the fracture toughness of the composite material made of this reinforced matrix and carbon fibres. The first step deals with the study of an epoxy matrix reinforced by a polyether-sulfone. This well-known material, as it is used in industrial formulation, allowed us to characterize all the parameters needed to obtain a good reinforcement as for instance the morphology, and also to compare two kinds of processes: thermal and electron beam curing. In fact, we are really interested in increasing fracture toughness of a vinyl-ester matrix that is not miscible with polyether-sulfone. So a copolymer which has a similar structure as polyether-sulfone is synthesized in order to obtain a miscible blend. The corresponding material has good fracture toughness, with an increase of 80 % for 15 % addition of thermoplastic. (author)

  2. Process for curing ionizing radiation-highly sensitive resin composition

    International Nuclear Information System (INIS)

    Araki, K.; Sasaki, T.; Tabei, K.; Goto, K.

    1979-01-01

    A process is described for curing a radiation curable composition consisting essentially of (a) an amide represented by the formula R,CONR 2 R 3 and (b) an unsaturated polyester resin by irradiating the composition with an ionizing radiation. R 1 is H, an alkyl groups having from 1 to 17 carbon atoms or an alkenyl groups having from 1 to 17 carbon atoms, and R 2 and R 3 are each -H, -CH 3 , or -CH 2 OH. R 1 and R 2 taken together represent alkylene having 2 to 5 carbon atoms

  3. Method for curing alkyd resin compositions by applying ionizing radiation

    International Nuclear Information System (INIS)

    Watanabe, T.; Murata, K.; Maruyama, T.

    1975-01-01

    An alkyd resin composition is prepared by dissolving a polymerizable alkyd resin having from 10 to 50 percent of oil length into a vinyl monomer. The polymerizable alkyd resin is obtained by a half-esterification reaction of an acid anhydride having a polymerizable unsaturated group and an alkyd resin modified with conjugated unsaturated oil having at least one reactive hydroxyl group per one molecule. The alkyd resin composition thus obtained is coated on an article, and ionizing radiation is applied on the article to cure the coated film thereon. (U.S.)

  4. A novel calorimetry technique for monitoring electron beam curing of polymer resins

    International Nuclear Information System (INIS)

    Chen, J.H.; Johnston, A.; Petrescue, L.; Hojjati, M.

    2006-01-01

    This paper describes the development of a calorimetry-based technique for monitoring of the curing of electron beam (EB) curable resins, including design of the calorimeter hardware and the development of an analytical model for calculating resin cure rates and radiation dose. Factors affecting the performance of the calorimeter were investigated. Experimental trials monitoring the curing of epoxy resin were conducted under single pass and multiple passes of EB irradiation. Results show that the developed calorimeter is a simple, inexpensive and reasonably accurate technique for monitoring the EB curing of cationic epoxies

  5. Preparation of unsaturated acrylic prepolymer and electron beam curing of its mixture with vinyl monomers

    International Nuclear Information System (INIS)

    Pyun, H.C.; Park, W.B.; Kim, K.Y.; Sung, K.Y.

    1980-01-01

    Electron beam curable prepolymers were prepared by the addition reaction of methyl methacrylate-glycidyl methacrylate copolymer with methacrylic acid, and electron beam curing was studied for the prepolymer and their mixtures of several kind of vinyl monomers. When the reaction was carried out in the presence of triethylbenzyl ammonium chloride in N,N-dimethyl formamide solution, the rate of addition reaction obeyed first-order kinetics. In the electron beam curing, the rate of gel formation of the prepolymer was slower than that of the mixtures of prepolymer and monomers. In the curing of mixtures of prepolymer with polyethyleneglycol dimethacrylates, the rate of gel formation increased with the increase in the degree of polymerization of polyethylene oxide fraction of polyethyleneglycol dimethacrylate, and decreased with the increase the polyethyleneglycol dimethacrylate content. The properties of cured coatings were also examined. (author)

  6. Influence of curing rate on softening in ethanol, degree of conversion, and wear of resin composite

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Peutzfeldt, Anne; Asmussen, Erik

    2011-01-01

    PURPOSE: To investigate the effect of curing rate on softening in ethanol, degree of conversion, and wear of resin composites. METHOD: With a given energy density and for each of two different light-curing units (QTH or LED), the curing rate was reduced by modulating the curing mode. Thus......, the irradiation of resin composite specimens (Filtek Z250, Tetric Ceram, Esthet-X) was performed in a continuous curing mode and in a pulse-delay curing mode. Wallace hardness was used to determine the softening of resin composite after storage in ethanol. Degree of conversion was determined by infrared...... exposed to the pulse-delay curing mode were softer than resin composites exposed to continuous cure (Pconversion (P

  7. Effect of various infection-control methods for light-cure units on the cure of composite resins.

    Science.gov (United States)

    Chong, S L; Lam, Y K; Lee, F K; Ramalingam, L; Yeo, A C; Lim, C C

    1998-01-01

    This study (1) compared the curing-light intensity with various barrier infection-control methods used to prevent cross contamination, (2) compared the Knoop hardness value of cured composite resin when various barrier control methods were used, and (3) correlated the hardness of the composite resin with the light-intensity output when different infection-control methods were used. The light-cure unit tips were covered with barriers, such as cellophane wrap, plastic gloves, Steri-shields, and finger cots. The control group had no barrier. Composite resins were then cured for each of the five groups, and their Knoop hardness values recorded. The results showed that there was significant statistical difference in the light-intensity output among the five groups. However, there was no significant statistical difference in the Knoop hardness values among any of the groups. There was also no correlation between the Knoop hardness value of the composite resin with the light-intensity output and the different infection-control methods. Therefore, any of the five infection-control methods could be used as barriers for preventing cross-contamination of the light-cure unit tip, for the light-intensity output for all five groups exceeded the recommended value of 300 W/m2. However, to allow a greater margin of error in clinical situations, the authors recommend that the plastic glove or the cellophane wrap be used to wrap the light-cure tip, since these barriers allowed the highest light-intensity output.

  8. EB-curing of coatings on wood composite boards

    International Nuclear Information System (INIS)

    Czvikovszky, T.; Czajlic, I.; Takacs, E.; Ille, A.; Salleh, N.G.; Alpar, T.

    1988-01-01

    The industrial radiation processing using low energy electron beam (EB) accelerators lower than 300 keV offers high speed, safe technologies for the chemical conversion of thin layer coatings. Because of the nonselective mode of initiating chain reaction polymerization involving free radicals in synthetic coating layers and suitable substrates, the EB curing of the coatings on woods and papers has particular advantage. Hungary decided to start an up-to-date EB line to process cement-bound (CB) wood chipboards with pigmented acrylic coatings. The CB wood chipboards contain more than 60 % of portland cement and up to 40 % of wood particles. They are produced as large boads of 6 - 16 mm thickness. In their fireproof character and other aspects, they are similar to asbestos-cement boards without containing carcinagenic asbestos, and are stable against moisture and atmospheric influences. EB-cured acrylate coating improved further those properties, and makes them valuable structural material. Oligomers and monomers as the main components of EB curable coatings, the irradiation with a Van de Graaff type electron accelerator of 2 MeV and the results are reported. The oligomers play the most important role in the formation of radiation curable coatings. (K.I.)

  9. The characteristics of epoxy resin cured by {gamma}-ray and E-beam

    Energy Technology Data Exchange (ETDEWEB)

    Nho, Y.C. E-mail: ycnho@kaeri.re.kr; Kang, Phil Hyun; Park, Jong Seok

    2004-10-01

    Epoxy resins are widely used as high-performance thermosetting resins for many industrial applications. In this study, the effect of an electron beam (E-beam) and {gamma}-ray irradiation on the curing of epoxy resins was investigated. Diglycidyl ether of bisphenol-A(DGEBA), diglycidyl ether of bisphenol-F(DGEBF) as epoxy resins, triarylsulfonium hexafluoroantimonate(TASHFA), and triarylsulfonium hexafluorophosphate(TASHFP) as initiators were used in this study. The chemical and mechanical characteristics of irradiated epoxy resins were compared after curing of E-beam and {gamma}-ray irradiation up to 50 kGy in N{sub 2} and air atmosphere. We ascertained the effect of oxygen on the radiation curing of epoxy resin. The thermal properties of cured epoxy were investigated using DMA and TGA. Mechanical properties such as flexural strength were measured. The chemical structures of cured epoxy were characterized by FT-NIR. The gel fraction and the stress at yield of epoxy resins irradiated by E-beam and {gamma}-ray in N{sub 2} atmosphere were also compared with those of epoxy resins irradiated by E-beam and {gamma}-ray in air.

  10. Contribution for study on curing of organic coatings in papers, by electron beam

    International Nuclear Information System (INIS)

    Taqueda, M.H.S.

    1986-01-01

    The behaviour of national raw material is studied: paper, resins vamishes used on the surface finishing furniture, when subnitted to electron beam curing in an inert atmosphere. The dosimetric control of the irradiation system was made by using CTA films. The minimum cure dose obtained for the EBC 1650/3009 varnish(national polyester) was 2.4 Mrad and of 2.0 Mrad for the EBC 1650/3010 (imported polyester from Germany). The optimun cure dose for both was 3.0 Mrad. The papers impregnated with EBC varnish of with conventional varnish were measured mechanically for resistance in traction and an evaluation of resistance of the finished surfaces with the ebc varnishes was made. The coatings obtained with the EBC varnishes manufactured nationally were compared with the conventional vamishes of thermal cure and with paper samples impregnated and cured in Germany. (author) [pt

  11. Crosslinking of thermoplastic composites using electron beam radiation

    International Nuclear Information System (INIS)

    Strong, A.B.; Black, S.R.; Bryce, G.R.; Olcott, D.D.

    1991-01-01

    The crosslinking of thermoset materials has been clearly demonstrated to improve many desirable physical and chemical properties for composite applications. While thermoplastic resins also offer many advantages for composite applications, they are not crosslinked and, therefore, may not meet the same property criteria as crosslinked thermosets. Electron beams have been used successfully for crosslinking non-reinforced thermoplastic materials. Electron beams have also been used for curing composite thermoset materials. This research utilizes electron beams to crosslink high performance thermoplastic composite materials (PEEK and PPS with glass and carbon fibers). The tensile strength and tensile modulus are compared under various crosslinking conditions. The method is found to have some advantages in potentially improving physical properties of thermoplastic composite materials

  12. Cure Cycle Optimization of Rapidly Cured Out-Of-Autoclave Composites

    Science.gov (United States)

    Dong, Anqi; Zhao, Yan; Zhao, Xinqing; Yu, Qiyong

    2018-01-01

    Out-of-autoclave prepreg typically needs a long cure cycle to guarantee good properties as the result of low processing pressure applied. It is essential to reduce the manufacturing time, achieve real cost reduction, and take full advantage of out-of-autoclave process. The focus of this paper is to reduce the cure cycle time and production cost while maintaining high laminate quality. A rapidly cured out-of-autoclave resin and relative prepreg were independently developed. To determine a suitable rapid cure procedure for the developed prepreg, the effect of heating rate, initial cure temperature, dwelling time, and post-cure time on the final laminate quality were evaluated and the factors were then optimized. As a result, a rapid cure procedure was determined. The results showed that the resin infiltration could be completed at the end of the initial cure stage and no obvious void could be seen in the laminate at this time. The laminate could achieve good internal quality using the optimized cure procedure. The mechanical test results showed that the laminates had a fiber volume fraction of 59–60% with a final glass transition temperature of 205 °C and excellent mechanical strength especially the flexural properties. PMID:29534048

  13. Electron beam processing of carbon fibre reinforced braided composites beams

    International Nuclear Information System (INIS)

    Halasz, L.; Zsigmond, B.; Czvikovszky, T.

    2002-01-01

    Complete text of publication follows. In this paper the possibility of producing a new type carbon fiber reinforced composite is examined by applying braiding, a well-known process of textile technology. The appearance of the new Hungarian carbon fiber with excellent mechanical properties in the market enables the development of newer type carbon fiber reinforced composites in the continuously widening range of engineering applications. Advanced hollow profiles, pipes and other composite products can be manufactured in continuous operation. A new way of composite production of this kind is the manufacturing of reinforcing structure by braiding technology producing a composite with sufficient mechanical properties from this cross directional fabric-like textile structure by impregnation. This manufacturing process can complete the variety of hollow products serving the same purpose as pultrusion or filament winding. This way a profile type framework element with a hollow cross section is manufactured having favorable mechanical properties. Owing to its small mass and high specific strength this product can be applied in dynamically loaded structures e.g. in the automotive industry. For crosslinking of the matrix the method of high-speed electron beam curing has been examined in order to reach continuous operation. The field of use and application of carbon fiber braided structures has a great chance especially in machine engineering and in the automotive industry. The main reason for this is that braiding processes are capable of producing structures having good mechanical properties at a low processing price. The mass of the composite load-bearing structure produced this way is one fifth of the steel product having similar geometry, and its specific mechanical properties are nearly as good as that of the most commonly applied semiproduct and structural component, the welded steel profile

  14. Anisotropic Dielectric Properties of Carbon Fiber Reinforced Polymer Composites during Microwave Curing

    Science.gov (United States)

    Zhang, Linglin; Li, Yingguang; Zhou, Jing

    2018-01-01

    Microwave cuing technology is a promising alternative to conventional autoclave curing technology in high efficient and energy saving processing of polymer composites. Dielectric properties of composites are key parameters related to the energy conversion efficiency during the microwave curing process. However, existing methods of dielectric measurement cannot be applied to the microwave curing process. This paper presented an offline test method to solve this problem. Firstly, a kinetics model of the polymer composites under microwave curing was established based on differential scanning calorimetry to describe the whole curing process. Then several specially designed samples of different feature cure degrees were prepared and used to reflect the dielectric properties of the composite during microwave curing. It was demonstrated to be a feasible plan for both test accuracy and efficiency through extensive experimental research. Based on this method, the anisotropic complex permittivity of a carbon fiber/epoxy composite during microwave curing was accurately determined. Statistical results indicated that both the dielectric constant and dielectric loss of the composite increased at the initial curing stage, peaked at the maximum reaction rate point and decreased finally during the microwave curing process. Corresponding mechanism has also been systematically investigated in this work.

  15. Comparing depth-dependent curing radiant exposure and time of curing of regular and flow bulk-fill composites

    Directory of Open Access Journals (Sweden)

    Jose Augusto RODRIGUES

    2017-08-01

    Full Text Available Abstract The effect of restoration depth on the curing time of a conventional and two bulk-fill composite resins by measuring microhardness and the respective radiosity of the bottom surface of the specimen was investigated. 1-, 3- and 5-mm thick washers were filled with Surefil SDR Flow–U (SDR, Tetric EvoCeram Bulk Fill-IVA (TEC or Esthet-X HD–B1 (EHD, and cured with Bluephase® G2 for 40s. Additional 1-mm washers were filled with SDR, TEC or EHD, placed above the light sensor of MARC®, stacked with pre-cured 1-, 3- or 5-mm washer of respective material, and cured for 2.5~60s to mimic 2-, 4- and 6-mm thick composite curing. The sensor measured the radiosity (EB at the bottom of specimen stacks. Vickers hardness (VH was measured immediately at 5 locations with triplicate specimens. Nonlinear regression of VH vs EB by VH=α[1-exp(-EB/β] with all thickness shows that the values of α, maximum hardness, are 21.6±1.0 kg/mm2 for SDR, 38.3±0.6 kg/mm2 for TEC and 45.3±2.6 kg/mm2 for EHD, and the values of β, rate parameter, are 0.40±0.06 J/cm2 for SDR, 0.77±0.04 J/cm2 for TEC and 0.58±0.09 J/cm2 for EHD. The radiosity of the bottom surface was calculated when the bottom surface of each material attained 80% of α of each material. The curing times for each material are in agreement with manufacturer recommendation for thickness. It is possible to estimate time needed to cure composite resin of known depth adequately by the radiosity and microhardness of the bottom surface.

  16. Comparing depth-dependent curing radiant exposure and time of curing of regular and flow bulk-fill composites.

    Science.gov (United States)

    Rodrigues, Jose Augusto; Tenorio, Ilana Pais; Mello, Ginger Baranhuk Rabello de; Reis, André Figueiredo; Shen, Chiayi; Roulet, Jean-François

    2017-08-21

    The effect of restoration depth on the curing time of a conventional and two bulk-fill composite resins by measuring microhardness and the respective radiosity of the bottom surface of the specimen was investigated. 1-, 3- and 5-mm thick washers were filled with Surefil SDR Flow-U (SDR), Tetric EvoCeram Bulk Fill-IVA (TEC) or Esthet-X HD-B1 (EHD), and cured with Bluephase® G2 for 40s. Additional 1-mm washers were filled with SDR, TEC or EHD, placed above the light sensor of MARC®, stacked with pre-cured 1-, 3- or 5-mm washer of respective material, and cured for 2.5~60s to mimic 2-, 4- and 6-mm thick composite curing. The sensor measured the radiosity (EB) at the bottom of specimen stacks. Vickers hardness (VH) was measured immediately at 5 locations with triplicate specimens. Nonlinear regression of VH vs EB by VH=α[1-exp(-EB/β)] with all thickness shows that the values of α, maximum hardness, are 21.6±1.0 kg/mm2 for SDR, 38.3±0.6 kg/mm2 for TEC and 45.3±2.6 kg/mm2 for EHD, and the values of β, rate parameter, are 0.40±0.06 J/cm2 for SDR, 0.77±0.04 J/cm2 for TEC and 0.58±0.09 J/cm2 for EHD. The radiosity of the bottom surface was calculated when the bottom surface of each material attained 80% of α of each material. The curing times for each material are in agreement with manufacturer recommendation for thickness. It is possible to estimate time needed to cure composite resin of known depth adequately by the radiosity and microhardness of the bottom surface.

  17. Monitoring cure of composite resins using frequency dependent electromagnetic sensing techniques

    Science.gov (United States)

    Kranbuehl, D. E.; Hoff, M. S.; Loos, A. C.; Freeman, W. T., Jr.; Eichinger, D. A.

    1988-01-01

    A nondestructive in situ measurement technique has been developed for monitoring and measuring the cure processing properties of composite resins. Frequency dependent electromagnetic sensors (FDEMS) were used to directly measure resin viscosity during cure. The effects of the cure cycle and resin aging on the viscosity during cure were investigated using the sensor. Viscosity measurements obtained using the sensor are compared with the viscosities calculated by the Loos-Springer cure process model. Good overall agreement was obtained except for the aged resin samples.

  18. An Evaluation of Fracture Toughness of Vinyl Ester Composites Cured under Microwave Conditions

    Science.gov (United States)

    Ku, H.; Chan, W. L.; Trada, M.; Baddeley, D.

    2007-12-01

    The shrinkage of vinyl ester particulate composites has been reduced by curing the resins under microwave conditions. The reduction in the shrinkage of the resins by microwaves will enable the manufacture of large vinyl ester composite items possible (H.S. Ku, G. Van Erp, J.A.R. Ball, and S. Ayers, Shrinkage Reduction of Thermoset Fibre Composites during Hardening using Microwaves Irradiation for Curing, Proceedings, Second World Engineering Congress, Kuching, Malaysia, 2002a, 22-25 July, p 177-182; H.S. Ku, Risks Involved in Curing Vinyl Ester Resins Using Microwaves Irradiation. J. Mater. Synth. Proces. 2002b, 10(2), p 97-106; S.H. Ku, Curing Vinyl Ester Particle Reinforced Composites Using Microwaves. J. Comp. Mater., (2003a), 37(22), p 2027-2042; S.H. Ku and E. Siores, Shrinkage Reduction of Thermoset Matrix Particle Reinforced Composites During Hardening Using Microwaves Irradiation, Trans. Hong Kong Inst. Eng., 2004, 11(3), p 29-34). In tensile tests, the yield strengths of samples cured under microwave conditions obtained are within 5% of those obtained by ambient curing; it is also found that with 180 W microwave power, the tensile strengths obtained for all duration of exposure to microwaves are also within the 5% of those obtained by ambient curing. While, with 360 W microwave power, the tensile strengths obtained for all duration of exposure to microwaves are 5% higher than those obtained by ambient curing. Whereas, with 540 W microwave power, the tensile strengths obtained for most samples are 5% below those obtained by ambient curing (H. Ku, V.C. Puttgunta, and M. Trada, Young’s Modulus of Vinyl Ester Composites Cured by Microwave Irradiation: Preliminary Results, J. Electromagnet. Waves Appl., 2007, 20(14), p. 1911-1924). This project, using 33% by weight fly ash reinforced vinyl ester composite [VE/FLYSH (33%)], is to further investigate the difference in fracture toughness between microwave cured vinyl ester particulate composites and those cured

  19. Effects of the curing methods on the fabrication of polycarbosilane derived SiCf/SiC composite

    International Nuclear Information System (INIS)

    Park, Ji Yeon; Kim, Weon Ju; Ryu, Woo Seog; Woo, Chang Hyun; Han, Bum Soo

    2005-01-01

    Silicon carbide has potential advantages for structural applications in the next generation energy system- VHTR, GFR and the fusion reactor due to its unique properties such as a good irradiation resistance and thermo-mechanical properties, less severe waste generation due to neutron activation and improved plant conversion efficiencies by higher operating temperatures. Among the several fabrication processes for SiC f /SiC composites, the polymer impregnation and pyrolysis (PIP) process is the only method derived from polymeric precursors. In the PIP process, the careful control of the oxygen content is important to avoid the property degradation at a high temperature because polymeric precursors are used as source materials of SiC ceramics. During the polymer precursor conversion process, unintended oxygen may be introduced for a cross-linking with producing the Si-O-Si bonds at the curing step. High oxygen content affects the degradation of the high temperature stability in SiC ceramics. Therefore, a decrease of the oxygen content is desirable to obtain SiC ceramics with the high temperature stability. One of the methods to reduce the oxygen content of polymer derived SiC ceramics is the irradiation curing process by gamma ray or electron beam. Polymer derived SiC ceramics with the low oxygen content prepared by the electron beam curing showed the improved thermal stability at a higher temperature. In this study, the electron beam (EB) and the thermal oxidation curing methods were applied to make SiC f /SiC composite using a polymer precursor, polycarbosilane (PCS) by the PIP process. And the evaluations of the curing effects, the pyrolysis behaviors and a high temperature stability were performed

  20. Curing mode affects bond strength of adhesively luted composite CAD/CAM restorations to dentin.

    Science.gov (United States)

    Lührs, Anne-Katrin; Pongprueksa, Pong; De Munck, Jan; Geurtsen, Werner; Van Meerbeek, Bart

    2014-03-01

    To determine the effect of curing mode and restoration-surface pre-treatment on the micro-tensile bond strength (μTBS) to dentin. Sandblasted CAD/CAM composite blocks (LAVA Ultimate, 3M ESPE) were cemented to bur-cut dentin using either the etch & rinse composite cement Nexus 3 ('NX3', Kerr) with Optibond XTR ('XTR', Kerr), or the self-etch composite cement RelyX Ultimate ('RXU', 3M ESPE) with Scotchbond Universal ('SBU', 3M ESPE). All experimental groups included different 'curing modes' (light-curing of adhesive and cement ('LL'), light-curing of adhesive and auto-cure of cement ('LA'), co-cure of adhesive through light-curing of cement ('AL'), or complete auto-cure ('AA')) and different 'restoration-surface pre-treatments' of the composite block (NX3: either a silane primer (Kerr), or the XTR adhesive; RXU: either silane primer (RelyX Ceramic Primer, 3M ESPE) and SBU, or solely SBU). After water-storage (7 days, 37°C), the μTBS was measured. Additionally, the degree of conversion (DC) of both cements was measured after 10min and after 1 week, either auto-cured (21°C/37°C) or light-cured (directly/through 3-mm CAD/CAM composite). The linear mixed-effects model (α=0.05) revealed a significant influence of the factors 'curing mode' and 'composite cement', and a less significant effect of the factor 'restoration-surface pre-treatment'. Light-curing 'LL' revealed the highest μTBS, which decreased significantly for all other curing modes. For curing modes 'AA' and 'AL', the lowest μTBS and a high percentage of pre-testing failures were reported. Overall, DC increased with light-curing and incubation time. The curing mode is decisive for the bonding effectiveness of adhesively luted composite CAD/CAM restorations to dentin. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. Influence of curing rate of resin composite on the bond strength to dentin

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Asmussen, E; Peutzfeldt, A

    2007-01-01

    @ 1000 mW/cm2) for all groups. A split Teflon mold was clamped to the treated dentin surface and filled with resin composite. The rate of cure was varied, using one of four LED-curing units of different power densities. The rate of cure was also varied using the continuous or pulse-delay mode....... In continuous curing mode, in order to give an energy density totaling 16 J/cm2, the power densities (1000, 720, 550, 200 mW/cm2) emitted by the various curing units were compensated for by the light curing period (16, 22, 29 or 80 seconds). In the pulse-delay curing mode, two seconds of light curing at one...... of the four power densities was followed by a one-minute interval, after which light cure was completed (14, 29, 27 or 78 seconds), likewise, giving a total energy density of 16 J/cm2. The specimens produced for each of the eight curing protocols and two resin composites (Tetric EvoCeram, Ivoclar Vivadent...

  2. Finite element modelling of composite castellated beam

    Directory of Open Access Journals (Sweden)

    Frans Richard

    2017-01-01

    Full Text Available Nowadays, castellated beam becomes popular in building structural as beam members. This is due to several advantages of castellated beam such as increased depth without any additional mass, passing the underfloor service ducts without changing of story elevation. However, the presence of holes can develop various local effects such as local buckling, lateral torsional buckling caused by compression force at the flange section of the steel beam. Many studies have investigated the failure mechanism of castellated beam and one technique which can prevent the beam fall into local failure is the use of reinforced concrete slab as lateral support on castellated beam, so called composite castellated beam. Besides of preventing the local failure of castellated beam, the concrete slab can increase the plasticity moment of the composite castellated beam section which can deliver into increasing the ultimate load of the beam. The aim of this numerical studies of composite castellated beam on certain loading condition (monotonic quasi-static loading. ABAQUS was used for finite element modelling purpose and compared with the experimental test for checking the reliability of the model. The result shows that the ultimate load of the composite castellated beam reached 6.24 times than the ultimate load of the solid I beam and 1.2 times compared the composite beam.

  3. Development of the fabrication process of SiC composite by radiation beam

    International Nuclear Information System (INIS)

    Park, Ji Yeon; Kim, Weon Ju; Jung, Choong Hwan; Woo, Chang Hyeon; Ryu, Woo Seog

    2006-01-01

    In order to operate the nuclear system at high temperatures, core materials with a good irradiation resistance at high temperatures must be developed. SiC composite is one of candidates for high temperature structural materials. Among several fabrication processes, the PIP process includes the curing and pyrolysis process. Generally, the thermal oxidation curing method has some disadvantages; difficulty in the control of oxygen contents and volatilization of many constituents. To overcome these disadvantages and reduce the process time, a new and improved method like the beam curing process has been proposed as one of the effective methods for the fabrication of SiC composite. In this study, the electron beam curing method in the PIP process was optimized to develop SiCf/SiC composite with low oxygen contents. Using the electron beam curing method with full doses of 2∼10 MGy and the pyrolysis process at 1300∼1400 .deg. C, composite with the oxygen content of less than 1 wt% could be obtained. Additionally, if the slurry impregnation and curing/pyrolysis processes were repeated several times, dense composite could be produced

  4. Cost estimates to guide manufacturing of composite waved beam

    International Nuclear Information System (INIS)

    Ye Jinrui; Zhang Boming; Qi Haiming

    2009-01-01

    A cost estimation model on the basis of manufacturing process has been presented. In the model, the effects of the material, labor, tool and equipment were discussed, and the corresponding formulas were provided. A method of selecting estimation variables has been provided based on a case study of composite waved beam using autoclave cure. The model parameters related to the process time estimation of the lay-up procedure were analyzed and modified for different part configurations. The result shows that there is little error while comparing the estimated process time with the practical one. The model is verified to be applicable to guide the design and manufacturing of the composite material

  5. Rubber composites cured with sulphur and peroxide and ...

    Indian Academy of Sciences (India)

    Besides classical applications of rubber products in tyres, ... application of sulphur curing systems leads to the forming ..... mobile sulphidic cross-links which promote crystallization of NR. ... PhD Thesis (Kingston, Ontario: Queen's University).

  6. Effect of bench time polymerization on depth of cure of dental composite resin

    Science.gov (United States)

    Harahap, K.; Yudhit, A.; Sari, F.

    2017-07-01

    The aim of this research was to investigate the effect of bench time before light cured polymerization on the depth of cure of dental composite resin. Nanofiller composite resin (Filtek Z350 XT,3M, ESPE,China) was used in this study. Sixty samples of nanofiller composite resin were made and divided into control and test groups with bench time for 0, 15, 30, 45, and 60 min. For the test group, composite resins were stored in refrigerator with 4°C temperatures. Meanwhile, for the control groups, the composite resin was stored at room temperature. The samples were prepared using metal mould with size diameter of 6 mm and 4 mm in thickness. Samples were cured for 20 s by using visible blue light curing unit. Part of samples that unpolymerized were removed by using a plastic spatula. The remaining parts of samples were measured by digital caliper and noted as depth of cure (mm). Data were analyzed to one-way ANOVA and LSD tests (p≤0.05). Results showed there was no significance differences between test groups (p=0.5). A 60 minutes bench time group showed the highest depth of cure value among test group, and it was almost similar with control group value. It can be concluded that longer bench time can increase the depth of cure of composite resin.

  7. Flexural behaviour of post-cured composites at oral-simulating temperatures.

    Science.gov (United States)

    Ho, C T; Vijayaraghavan, T V; Lee, S Y; Tsai, A; Huang, H M; Pan, L C

    2001-07-01

    Post-curing treatments have been known to improve the mechanical stability of visible light-cured composites. After individual post-curing treatment, the flexural strength (FS) of four commercial direct/indirect placement composite materials which differ greatly in composition [oligocarbonate dimethacrylate (OCDMA)-based Conquest C & B (CQT), Bisphenol-A glycidyl dimethacrylate (BisGMA)-based Charisma, urethane dimethacrylate (UDMA)-based Concept (CCT), and BisGMA/UDMA-based Dentacolor] was evaluated under water in the temperature range of 12-50 degrees C. A control series was tested in air at room temperature (25 +/- 1 degrees C). Data were analysed using ANOVA and Duncan's test. Flexural strengths overall decreased (20-40%, P OCDMA-based materials. Post-cured composites can be significantly affected by exposure to oral environments. Different composition determines the degree of influence.

  8. The development of PVC-laminated steel sheet by an electron beam curing method

    International Nuclear Information System (INIS)

    Masuhara, Ken-ichi; Koshiishi, Kenji; Tomosue, Takao; Mori, Koji; Honma, Nobuyuki

    1988-01-01

    Polyvinyl chloride (PVC) film-laminated steel sheets are used for household electric appliances and building materials. Those are produced usually by pressing a PVC film onto a steel sheet imediately after a themosetting adhesive has been applied to the sheet and curing. However, a major problem of this method is that the appearance of the PVC films such as gloss and embossment changes during pressing due to the heat that is required for causing bonding, therefore, the development of an adhesive which can be cured at lower temperature is necessary. Nisshin Steel Co., Ltd. has developed PVC film-laminated steel sheets for which electron beam (EB) curable adhesives are used to overcome this problem. The advantage of these adhesives is that they can be quickly cured at room temperature. The production procedure of PVC-laminated steel sheets by EB curing is outlined. But this method has encountered two problems: poor adhesion between substrates and adhesive due to the residual stress, and the deterioration of the PVC films due to EB irradiation. EB curable adhesives are mainly composed of acrylic ester oligomers and monomers, and thier adhesion was improved by organic pretreatment. On the other hand, EB-proof PVC films were developed. The general properties of PVC-laminated steel sheets produced by EB curing are reported. (K.I.)

  9. Effect of different light curing units on Knoop hardness and temperature of resin composite

    OpenAIRE

    Guiraldo Ricardo; Consani Simonides; Xediek Consani Rafael; Mendes Wilson; Lympius Thais; Coelho Sinhoreti Mario

    2009-01-01

    Aim: To evaluate the influence of quartz tungsten halogen and plasma arc curing (PAC) lights on Knoop hardness and change in polymerization temperature of resin composite. Materials and Methods: Filtek Z250 and Esthet X composites were used in the shade A3. The temperature increase was registered with Type-k thermocouple connected to a digital thermometer (Iopetherm 46). A self-cured polymerized acrylic resin base was built in order to guide the thermocouple and to support the dentin disk ...

  10. Optimal Design of Laminated Composite Beams

    DEFF Research Database (Denmark)

    Blasques, José Pedro Albergaria Amaral

    model for the analysis of laminated composite beams is proposed. The structural analysis is performed in a beam finite element context. The development of a finite element based tool for the analysis of the cross section stiffness properties is described. The resulting beam finite element formulation...... is able to account for the effects of material anisotropy and inhomogeneity in the global response of the beam. Beam finite element models allow for a significant reduction in problem size and are therefore an efficient alternative in computationally intensive applications like optimization frameworks...... design of laminated composite beams. The devised framework is applied in the optimal design of laminated composite beams with different cross section geometries and subjected to different load cases. Design criteria such as beam stiffness, weight, magnitude of the natural frequencies of vibration...

  11. An Enhanced Vacuum Cure Technique for On-Aircraft Repair of Carbon-Bismaleimide Composites

    Science.gov (United States)

    Rider, Andrew N.; Baker, Alan A.; Wang, Chun H.; Smith, Graeme

    2011-06-01

    Carbon/bismaleimide (BMI) composite is increasingly employed in critical load carrying aircraft structures designed to operate at temperatures approaching 180°C. The high post-cure temperature (above 220°C) required to fully react the BMI resin, however, renders existing on-aircraft prepreg or wet layup repair methods invalid. This paper presents a new on-aircraft repair technique for carbon/BMI composites. The composite prepregs are first warm-staged to improve the ability to evacuate entrapped air. Then the patch is cured in the scarf cavity using the vacuum bag technique, followed by off-aircraft post-cure. The fully cured patch then can be bonded using a structural adhesive.

  12. Structural investigation of e-beam cured epoxy resins through solid state NMR

    International Nuclear Information System (INIS)

    Alessi, Sabina; Spinella, Alberto; Caponetti, Eugenio; Dispenza, Clelia; Spadaro, Giuseppe

    2012-01-01

    In this paper the network structure of e-beam cured DGEBF based epoxy resins is investigated. Two epoxy systems, having different reactivity and cured in different process conditions, were analyzed through solid state NMR spectroscopy. The analysis shows that the more reactive system has higher cross-linking density and higher uniformity of network distribution. Similar information were obtained, in a previous work, on the same systems through dynamic mechanical thermal analysis. It is worth noting that unlike DMTA tests, which interfere with the molecular structure of the analyzed material, due to the heating during the analysis itself, more reliable information, without any artefact, are obtained by solid state NMR, carried out at constant room temperature. - Highlights: ► The structure of two e-beam cured epoxy systems is investigated through solid state NMR. ► The aim is to have direct information about the structure without inducing modifications. ► The different molecular structures are able to emphasize the response of solid state NMR. ► T 1 H, T 1ρ H and T CH measurements indicate different cross-linking degrees. ► The NMR results are in agreement with DMTA analysis performed in a previous paper.

  13. Thermographic analysis of the effect of composite type, layering method, and curing light on the temperature rise of photo-cured composites in tooth cavities.

    Science.gov (United States)

    Kim, Min-Jung; Kim, Ryan Jin-Young; Ferracane, Jack; Lee, In-Bog

    2017-10-01

    The purpose of this study was to investigate temperature rise in the composite and dentin of a class I cavity in extracted human molars under different restoration conditions, including the use of different composite types, layering methods, and curing lights. Open occlusal cavities were prepared on 28 extracted human molars. A conventional (Filtek Z250) and a bulk-fill (Filtek Bulk Fill Posterior; BFP) composite were used to restore the preparations. BFP was incrementally layered or bulk-filled. Bulk-filled BFP was cured with two different lights, the Elipar S10 and the BeLite. Each layer was illuminated for 20s, while thermograms of the specimens were recorded for 100s using an infrared thermal camera. Temperature changes on the composite and dentin surfaces were obtained at points of interest (POI) pertaining to successive incremental distances of 0.75mm from the top of the cavity to the pulp. The polymerization kinetics of each composite was determined using photo-differential scanning calorimetry. The greatest temperature rise was observed 0.75mm apical from the top of the cavity. All groups showed over 6°C maximum temperature rise (ΔT max ) at the pulpal side of the dentin. Upon curing, Z250 reached ΔT=5°C faster than BFP; however, ΔT max of the two composites were comparable at any POI. Bulk filling showed greater ΔT max than incremental filling at 0.75mm apical from the top and in the middle of the cavity. The Elipar S10 light generated faster temperature changes in the curing composite at all recorded positions throughout the depth of the cavity and greater ΔT max in all POIs compared to BeLite. Real-time thermographic analysis demonstrated that the composite type and layering method did not influence the temperature rise at the pulpal side of dentin during composite restoration of an occlusal preparation in a tooth. The amount and initial rate of temperature increase was most affected by the radiant exposure of the light curing unit. Within the

  14. Brillouin optical correlation domain analysis in composite material beams

    DEFF Research Database (Denmark)

    Stern, Yonatan; London, Yosef; Preter, Eyal

    2017-01-01

    Structural health monitoring is a critical requirement in many composites. Numerous monitoring strategies rely on measurements of temperature or strain (or both), however these are often restricted to point-sensing or to the coverage of small areas. Spatially-continuous data can be obtained...... with optical fiber sensors. In this work, we report high-resolution distributed Brillouin sensing over standard fibers that are embedded in composite structures. A phase-coded, Brillouin optical correlation domain analysis (B-OCDA) protocol was employed, with spatial resolution of 2 cm and sensitivity of 1 °K...... or 20 micro-strain. A portable measurement setup was designed and assembled on the premises of a composite structures manufacturer. The setup was successfully utilized in several structural health monitoring scenarios: (a) monitoring the production and curing of a composite beam over 60 h; (b...

  15. Depth of Cure of New Flowable Composite Resins

    Science.gov (United States)

    2012-03-30

    we met. His encouragement and undiminished love for the past 20 years has been my motivation. This thesis is also dedicated to my four children ...assessed to be the most commonly used by dentists. Therefore, the depths of cure data from this study are pertinent to the practice of dentistry ...Continuing Education in Dentistry . Http://cde.dentalaegis.com Dai Q, Bertrand S. Wear resistance of Surefil SDR Flow posterior flowable base. JDR

  16. In vitro analysis of shear bond strength and adhesive remnant index comparing light curing and self-curing composites

    Directory of Open Access Journals (Sweden)

    Murilo Gaby Neves

    2013-06-01

    Full Text Available OBJECTIVE: To evaluate, in vitro, the shear bond strength of self-curing (ConciseTM - 3M and Alpha Plast - DFL and light-curing composites (TransbondTM XT - 3M and Natural Ortho - DFL used in orthodontics bonding, associated to Morelli metal brackets, with further analysis of adhesive remnant index (ARI and enamel condition in scanning electron microscopy (SEM. METHODS: Forty human premolars, just extracted and stored in physiologic solution 0.9 % were used. Randomly, these samples were divided in four groups: G1 group, the brackets were bonded with ConciseTM - 3M composite; in G2 group, Alpha Plast - DFL composite was used; in G3 group, TransbondTM XT - 3M was used; in G4 group, Natural Ortho - DFL composite was used. These groups were submitted to shear strength tests in universal testing machine, at 0.5 mm per minute speed. RESULTS: Statistical difference between G3 and G4 groups was recorded, as G4 showing higher strength resistance than G3. In the other hand, there were no statistical differences between G1, G2 and G3 and G1, G2 and G4 groups. ARI analysis showed that there was no statistical difference between the groups, and low scores were recorded among then. The scanning electron microscopy (SEM analysis revealed the debonding spots and the enamel surface integrity. CONCLUSIONS: Shear bond strength was satisfactory and similar between the composites, however Natural Ortho - DFL revealed best comparing to TransbondTM XT - 3M.

  17. Bulk-fill resin composites: polymerization contraction, depth of cure, and gap formation.

    Science.gov (United States)

    Benetti, A R; Havndrup-Pedersen, C; Honoré, D; Pedersen, M K; Pallesen, U

    2015-01-01

    The bulk-filling of deep, wide dental cavities is faster and easier than traditional incremental restoration. However, the extent of cure at the bottom of the restoration should be carefully examined in combination with the polymerization contraction and gap formation that occur during the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk-fill materials produced a significantly larger depth of cure and polymerization contraction. Although most of the bulk-fill materials exhibited a gap formation similar to that of the conventional resin composite, two of the low-viscosity bulk-fill resin composites, x-tra base and Venus Bulk Fill, produced larger gaps.

  18. Statics and rotational dynamics of composite beams

    CERN Document Server

    Ghorashi, Mehrdaad

    2016-01-01

    This book presents a comprehensive study of the nonlinear statics and dynamics of composite beams and consists of solutions with and without active elements embedded in the beams. The static solution provides the initial conditions for the dynamic analysis. The dynamic problems considered include the analyses of clamped (hingeless) and articulated (hinged) accelerating rotating beams. Two independent numerical solutions for the steady state and the transient responses are presented. The author illustrates that the transient solution of the nonlinear formulation of accelerating rotating beam converges to the steady state solution obtained by the shooting method. Other key areas considered include calculation of the effect of perturbing the steady state solution, coupled nonlinear flap-lag dynamics of a rotating articulated beam with hinge offset and aerodynamic damping, and static and dynamic responses of nonlinear composite beams with embedded anisotropic piezo-composite actuators. The book is intended as a t...

  19. A Fourier transform Raman spectroscopy analysis of the degree of conversion of a universal hybrid resin composite cured with light-emitting diode curing units.

    Science.gov (United States)

    Lindberg, Anders; Emami, Nazanin; van Dijken, Jan W V

    2005-01-01

    The degree of conversion (DC), of a universal hybrid resin composite cured with LED curing units with low and high power densities and a 510 mW/cm2 quartz tungsten halogen unit, was investigated with Fourier Transform Raman spectroscopy. Three curing depths (0, 2, 4mm) and 0 and 7 mm light guide tip - resin composite (LT - RC) distances were tested. The DC of the LED units varied between 52.3% - 59.8% at the top surface and 46.4% - 57.0% at 4 mm depth. The DC of specimen cured with a 0 mm LT- RC distance at 4 mm depth varied between 50.8% - 57.0% and with 7 mm distance between 46.4% - 55.4%. The low power density LED unit showed a significantly lower DC for both distances at all depth levels compared to the other curing units (p units were only found at the 4 mm depth level cured from 7 mm distance (p units. It can be concluded that the improved LED curing units could cure the studied resin composite to the same DC as the control unit.

  20. Pulp chamber temperature rise during curing of resin-based composites with different light-curing units.

    Science.gov (United States)

    Durey, Kathryn; Santini, Ario; Miletic, Vesna

    2008-01-01

    The purpose of the present study was to measure the intrapulpal temperature rise occurring during polymerisation of different shades of resin-based composites (RBCs), and two light-emitting diode (LED) units. Seventy non-carious permanent molars, that had been extracted for orthodontic purposes and stored in 2% thymol for not more than four months, were selected. Patient age range was 11-18 years. Standard cavity preparation with standardised remaining dentine thickness and placement of thermocouples (TCs) was prepared using a novel split-tooth technique. Cavities were filled with one of two shades of RBC (A2 and C4, Filtek Z250, 3M ESPE, Seefeld, Germany), and cured with two LED high-intensity units (Elipar Freelight2, 3M ESPE, Seefeld, Germany; Bluephase, Ivoclar Vivadent, Schaan, Liechtenstein) and a conventional halogen light-curing unit (LCU) (Prismetics Lite 2, Dentsply, Weybridge, Surrey, UK) as a control. Pulp temperature rises during bonding [A2 results: H;2.67/0.48:E;5.24/1.32;B;5.99/1.61] were always greater than during RBC curing [A2 results: 2.44/0.63;E3.34/0.70;B3.38/0.60], and these were significant for both LED lights but not for the halogen control, irrespective of shade (Mann-Whitney test: 95% confidence limits). Temperature rises were at times in excess of the values normally quoted as causing irreversible pulp damage. Pulp temperature rises during bonding were higher with the LED lights than with the halogen control. There was no significant difference in temperature rise between the two LED lights when bonding but there was a significant difference between the two LED lights and the halogen control LCUs (Kruskal-Wallis Test: 95% confidence limits). The results support the view that there is a potential risk for heat-induced pulpal injury when light-curing RBCs. The risk is greater during bonding and with high energy, as compared to low-energy output systems. As the extent of tolerable thermal trauma by the pulp tissues is unknown, care and

  1. A Comparison of Curing Process-Induced Residual Stresses and Cure Shrinkage in Micro-Scale Composite Structures with Different Constitutive Laws

    Science.gov (United States)

    Li, Dongna; Li, Xudong; Dai, Jianfeng; Xi, Shangbin

    2018-02-01

    In this paper, three kinds of constitutive laws, elastic, "cure hardening instantaneously linear elastic (CHILE)" and viscoelastic law, are used to predict curing process-induced residual stress for the thermoset polymer composites. A multi-physics coupling finite element analysis (FEA) model implementing the proposed three approaches is established in COMSOL Multiphysics-Version 4.3b. The evolution of thermo-physical properties with temperature and degree of cure (DOC), which improved the accuracy of numerical simulations, and cure shrinkage are taken into account for the three models. Subsequently, these three proposed constitutive models are implemented respectively in a 3D micro-scale composite laminate structure. Compared the differences between these three numerical results, it indicates that big error in residual stress and cure shrinkage generates by elastic model, but the results calculated by the modified CHILE model are in excellent agreement with those estimated by the viscoelastic model.

  2. Depth of Cure of Proximal Composite Restorations using a New Perforated Metal Matrix

    Science.gov (United States)

    2016-06-01

    on the clinical performance of posterior composite restorations after 4 years. In the study by Hofmann and Hunecke,17 the effect of light curing...or translucent matrices for class II composite restorations: 4-year clinical follow-up findings. Clin Oral Invest 2011 (15):39-47. 17 Hofmann N

  3. Single Vacuum Bagging and Autoclave Curing System Influence on Physical and Mechanical Properties of Phenolic Composites

    Directory of Open Access Journals (Sweden)

    M.A. Mirzapour

    2010-12-01

    Full Text Available Industrial production of thermoset composite components involves the application of a vacuum bagging and autoclave pressure to minimize void percentage, usually to less than 5%. Phenolic resin systems generate water as a reaction byproduct via condensation reactions during curing at elevated temperatures. In this paper, vacuum bagging and simple manufactured autoclave curing systems are used for manufacturing of asbestos/phenolic composites and the effects of processing conditions on manufactured composites are investigated. The traditional single-vacuum-bag process is unable to manage the volatiles effectively, resulting in inferior laminates having voids. The autoclave process cure cycle (temperature/pressure profiles for the selected composite system is designed to emit volatiles during curing reactions effectively and produce composites with low void contents and excellent mechanical properties. Laminate consolidation quality is characterized by optical photomicrography for the cross-sections and measurements of void content and mechanical properties. The void content of phenolic composites as opposed to other composites increases as pressure increases up to 3 bar and it is then decreased beyond it. A product of 124% lower void content, 13% higher density, 24% higher flexural strength and 27% higher flexural modulus can be fabricated in composites obtainedby autoclave processing.

  4. Cure kinetics and mechanical interfacial characteristics of zeolite/DGEBA composites

    International Nuclear Information System (INIS)

    Park, Soo Jin; Kim, Young Mi; Shin, Jae Sup

    2003-01-01

    In this work, the zeolite/diglycidylether of bisphenol A(DGEBA) systems were investigated in terms of the cure kinetics and mechanical interfacial properties of the composites. The 4, 4-Diamino Diphenyl Methane(DDM) was used as a curing agent for epoxy. Two types of zeolite(PZ) were prepared with 15 and 35 wt% KOH treatments(15-BZ and 35-BZ, respectively) for 24 h, and their surface characteristics were studied by X-ray Photoelectron Spectroscopy (XPS) and X-Ray Diffraction (XRD). Cure kinetics of the composites were examined in the context of Differential Scanning Calorimetry(DSC), and mechanical interfacial properties were investigated in critical stress intensity factor(K IC ) and critical strain energy release rate(G IC ). In the results of XPS and XRD, sodium ion(Na) of zeolite was exchanged for potassium ion(K), resulting from the treatment of KOH. Also, Si 2p /A1 2p composition ratios of the treated zeolite were increased, which could be attributed to the weakening of A1-O bond in framework. Cure activation energy(E a ) of 15-BZ composites was decreased, whereas K IC and G IC were increased, compared with those of the pure zeolite/DGEBA composites. It was probably accounted that the acidity of zeolite was increased by surface treatments and the cure reaction between zeolite and epoxy was influenced on the increased acidity of zeolite

  5. A method for hardening or curing adhesives for flocking thermally sensitive substrata by means of an electron-beam

    International Nuclear Information System (INIS)

    Nablo, S.V.; Fussa, A.D.

    1975-01-01

    The invention relates to a method for hardening or curing adhesives for flocking thermally sensitive substrata by means of an electron-beam. That method consists in accurately adjusting the parameters of irradiation by an electron-beam and the beam velocity so as to obtain, a very rapid hardening of adhesives used for fixing flocking materials, or the like, to thermally sensitive substrate. That can be applied to hardening or curing adhesives for flocking thermally-sensitive substrata which normally restrict the hardening rate [fr

  6. Fast Cure Repair Kit for Composites, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has a need for technologies that will enable them to repair damage to composite structures. Fiber-reinforced polymer composite materials are fast gaining ground...

  7. Steel Protective Coating Based on Plasticized Epoxy Acrylate Formulation Cured by Electron Beam Irradiation

    International Nuclear Information System (INIS)

    Ibrahim, M.S.; Said, H.M.; Mohamed, I.M.; Mohamed, H.A.; Kandile, N.G.

    2011-01-01

    Electron beam (EB) was used to cure coatings based on epoxy acrylate oligomer (EA) and different plasticizers such as epoxidized soybean oil, glycerol and castor oil. The effect of irradiation doses (10, 25, 50 kGy) on the curing epoxy acrylate formulations containing plasticizers was studied. In the addition, the effect of the different plasticizers on the end use performance properties of epoxy acrylate coatings such as hardness, bending, adhesion, acid and alkali resistance tests were investigated. It was observed that the incorporation of castor oil in epoxy acrylate, diluted by 1,6 hexandiol diacrylate monomer (HD) with a ratio (EA 70%, HD 20%, castor oil 10%) under the dose 10 kGy improved the physical, chemical and mechanical properties of cured films than the other plasticizers. On the other hand, sunflower free fatty acids were epoxidized in-situ under well established conditions and then was subjected to react with aniline in sealed ampoules under inert atmosphere at 140 degree C. The produced adduct was added at different concentrations to epoxy acrylate coatings under certain EB irradiation dose and then evaluated as corrosion inhibitors for carbon steel surfaces in terms of weight loss measurements and corrosion resistance tests. It was observed that the formula containing 0.4 gm of aniline adduct / 100 gm epoxy acrylate resin gave the best corrosion protection for carbon steel

  8. Combined Effect of Initial Curing Temperature and Crack Width on Chloride Penetration in Reinforced Concrete Beams

    Directory of Open Access Journals (Sweden)

    Elkedrouci Lotfi

    2018-01-01

    Full Text Available Reinforced concrete (RC structures are gradually being degraded all over the world, largely due to corrosion of the embedded steel bars caused by an attack of chloride penetration. Initial curing would be regarded as one factor influencing chloride diffusion in concrete in combination with cover cracking that is also of great attention for reinforced structures. In this study, a non-steady state diffusion test of chloride ion involving RC beam specimens with a water-to-cement ratio of 0.5, initial curing temperatures of 5°C or 20°C and three types of crack widths ranging from 0 to 0.2mm was performed. Chloride content at 5°C or was determined. The results show that the higher chloride content was obtained in condition of crack width large than 0.1mm with low initial curing temperature and there are no obvious differences in chloride content when the crack width was not larger than 0.1mm.

  9. Radiation Supporting Synthezis and Curing of Composites Suitable for Practical Applications

    International Nuclear Information System (INIS)

    Przybytniak, G.; Antoniak, M.; Nowicki, A.; Mirkowski, K.; Walo, M.

    2011-01-01

    Epoxy resins (ER) due to favorable combination of superior mechanical and thermal properties with unusual radiation resistance play an important role in some nuclear and aerospace industries. They are also widely used as matrices of reinforced composites since the homogeneous dissipation of fillers in the non-cured material is uncomplicated and efficient. Curing procedure is a very important factor determining final features of the epoxy resin and its composite. It was confirmed that irradiation facilitates molecular mobility and decreases glass transition as a result of chain scission. On the other hand, the increase in local mobility accelerates crosslinking thus the total effect is dependent on the relation between these two processes. Larieva reported that the ratio between degradation and crosslinking is 0.43, thus under selected conditions yield of curing more than twice prevails over yield of decomposition. The nature of hardener and its radiosensitivity also significantly influence the radiation induced curing. During exposure to ionizing radiation the binders participate in the processes initiated both by radiation and by heating, as curing is highly exothermic and considerably increases temperature of the system. Application of radiation treatment lowers energy consumption, shortens curing time and decreases curing temperature enhancing dimensional stability. In the past some attempts were made to improve heat resistance and strength of epoxy resins by the incorporation of various particles, e.g. silica, carbon nanotubes, montmorillonite, etc, however the results were unambiguous. In the reported studies the effects of radiation and thermal curing were investigated for ER and its composites either in the presence of cationic initiator or amine hardener

  10. Radiation Supporting Synthezis and Curing of Composites Suitable for Practical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Przybytniak, G.; Antoniak, M.; Nowicki, A.; Mirkowski, K.; Walo, M. [Institute of Nuclear Chemistry and Technology, Dorodna 16 Str., 03-195 Warsaw (Poland)

    2011-07-01

    Epoxy resins (ER) due to favorable combination of superior mechanical and thermal properties with unusual radiation resistance play an important role in some nuclear and aerospace industries. They are also widely used as matrices of reinforced composites since the homogeneous dissipation of fillers in the non-cured material is uncomplicated and efficient. Curing procedure is a very important factor determining final features of the epoxy resin and its composite. It was confirmed that irradiation facilitates molecular mobility and decreases glass transition as a result of chain scission. On the other hand, the increase in local mobility accelerates crosslinking thus the total effect is dependent on the relation between these two processes. Larieva reported that the ratio between degradation and crosslinking is 0.43, thus under selected conditions yield of curing more than twice prevails over yield of decomposition. The nature of hardener and its radiosensitivity also significantly influence the radiation induced curing. During exposure to ionizing radiation the binders participate in the processes initiated both by radiation and by heating, as curing is highly exothermic and considerably increases temperature of the system. Application of radiation treatment lowers energy consumption, shortens curing time and decreases curing temperature enhancing dimensional stability. In the past some attempts were made to improve heat resistance and strength of epoxy resins by the incorporation of various particles, e.g. silica, carbon nanotubes, montmorillonite, etc, however the results were unambiguous. In the reported studies the effects of radiation and thermal curing were investigated for ER and its composites either in the presence of cationic initiator or amine hardener.

  11. Brillouin Optical Correlation Domain Analysis in Composite Material Beams

    Directory of Open Access Journals (Sweden)

    Yonatan Stern

    2017-10-01

    Full Text Available Structural health monitoring is a critical requirement in many composites. Numerous monitoring strategies rely on measurements of temperature or strain (or both, however these are often restricted to point-sensing or to the coverage of small areas. Spatially-continuous data can be obtained with optical fiber sensors. In this work, we report high-resolution distributed Brillouin sensing over standard fibers that are embedded in composite structures. A phase-coded, Brillouin optical correlation domain analysis (B-OCDA protocol was employed, with spatial resolution of 2 cm and sensitivity of 1 °K or 20 micro-strain. A portable measurement setup was designed and assembled on the premises of a composite structures manufacturer. The setup was successfully utilized in several structural health monitoring scenarios: (a monitoring the production and curing of a composite beam over 60 h; (b estimating the stiffness and Young’s modulus of a composite beam; and (c distributed strain measurements across the surfaces of a model wing of an unmanned aerial vehicle. The measurements are supported by the predictions of structural analysis calculations. The results illustrate the potential added values of high-resolution, distributed Brillouin sensing in the structural health monitoring of composites.

  12. Brillouin Optical Correlation Domain Analysis in Composite Material Beams.

    Science.gov (United States)

    Stern, Yonatan; London, Yosef; Preter, Eyal; Antman, Yair; Diamandi, Hilel Hagai; Silbiger, Maayan; Adler, Gadi; Levenberg, Eyal; Shalev, Doron; Zadok, Avi

    2017-10-02

    Structural health monitoring is a critical requirement in many composites. Numerous monitoring strategies rely on measurements of temperature or strain (or both), however these are often restricted to point-sensing or to the coverage of small areas. Spatially-continuous data can be obtained with optical fiber sensors. In this work, we report high-resolution distributed Brillouin sensing over standard fibers that are embedded in composite structures. A phase-coded, Brillouin optical correlation domain analysis (B-OCDA) protocol was employed, with spatial resolution of 2 cm and sensitivity of 1 °K or 20 micro-strain. A portable measurement setup was designed and assembled on the premises of a composite structures manufacturer. The setup was successfully utilized in several structural health monitoring scenarios: (a) monitoring the production and curing of a composite beam over 60 h; (b) estimating the stiffness and Young's modulus of a composite beam; and (c) distributed strain measurements across the surfaces of a model wing of an unmanned aerial vehicle. The measurements are supported by the predictions of structural analysis calculations. The results illustrate the potential added values of high-resolution, distributed Brillouin sensing in the structural health monitoring of composites.

  13. Monitoring cure properties of out-of-autoclave BMI composites using IFPI sensor

    Science.gov (United States)

    Kaur, Amardeep; Anandan, Sudharshan; Yuan, Lei; Watkins, Steve E.; Chandrashekhara, K.; Xiao, Hai; Phan, Nam

    2016-04-01

    A non-destructive technique for inspection of a Bismaleimide (BMI) composite is presented using an optical fiber sensor. High performance BMI composites are used for Aerospace application for their mechanical strength. They are also used as an alternative to toughened epoxy resins. A femtosecond-laser-inscribed Intrinsic Fabry-Perot Interferometer (IFPI) sensor is used to perform real time cure monitoring of a BMI composite. The composite is cured using the out-of-autoclave (OOA) process. The IFPI sensor was used for in-situ monitoring; different curing stages are analyzed throughout the curing process. Temperature-induced-strain was measured to analyze the cure properties. The IFPI structure comprises of two reflecting mirrors inscribed on the core of the fiber using a femtosecond-laser manufacturing process. The manufacturing process makes the sensor thermally stable and robust for embedded applications. The sensor can withstand very high temperatures of up to 850 °C. The temperature and strain sensitivities of embedded IFPI sensor were measured to be 1.4 pm/μepsilon and 0.6 pm/μepsilon respectively.

  14. Glass transition and degree of conversion of a light-cured orthodontic composite

    Directory of Open Access Journals (Sweden)

    Michela M. D. S. Sostena

    2009-12-01

    Full Text Available OBJECTIVE: This study evaluated the glass transition temperature (Tg and degree of conversion (DC of a light-cured (Fill Magic versus a chemically cured (Concise orthodontic composite. MATERIAL AND METHODS: Anelastic relaxation spectroscopy was used for the first time to determine the Tg of a dental composite, while the DC was evaluated by infrared spectroscopy. The light-cured composite specimens were irradiated with a commercial LED light-curing unit using different exposure times (40, 90 and 120 s. RESULTS: Fill Magic presented lower Tg than Concise (35-84ºC versus 135ºC, but reached a higher DC. CONCLUSIONS: The results of this study suggest that Fill Magic has lower Tg than Concise due to its higher organic phase content, and that when this light-cured composite is used to bond orthodontic brackets, a minimum energy density of 7.8 J/cm² is necessary to reach adequate conversion level and obtain satisfactory adhesion.

  15. Combined effect of high curing temperature and crack width on chloride migration in reinforced concrete beams

    Science.gov (United States)

    Elkedrouci, L.; Diao, B.; Pang, S.; Li, Y.

    2018-03-01

    Deterioration of reinforced concrete structures is a serious concern in the construction engineering, largely due to chloride induced corrosion of reinforcement. Chloride penetration is markedly influenced by one or several major factors at the same time such as cuing in combination with different crack widths which have spectacular effect on reinforced concrete structures. This research presents the results of an experimental investigation involving reinforced concrete beams with three different crack widths ranging from 0 to 0.2mm, curing temperatures of 20°C or 40°C and water-to-cement of 0.5. Chloride content profiles were determined under non-steady state diffusion at 20°C. Based on the obtained results, higher chloride content was obtained under condition of high curing temperature in combination with large crack more than 0.1mm and there are no significant differences between narrow crack width (less than 0.1 mm) and beams without crack (0 mm).

  16. Mathematical Model For Autoclave Curing Of Unsaturated Polyester Based Composite Materials

    Directory of Open Access Journals (Sweden)

    Adnan A. Abdul Razak

    2013-05-01

    Full Text Available Heat transfer process involved in the autoclave curing of fiber-reinforced thermosetting composites is investigated numerically. A model for the prediction of the temperature and the extent of the reaction across the laminate thickness during curing process in the autoclave of unsaturated polyester based composite has been developed. The governing equation for one dimensional heat transfer, and accounting for the heat generation due to the exothermic cure reaction in the composites had been used.  It was found that the temperature at the central of the laminate increases up to the external imposed temperature, because of the thermal conductivity of the resin and fiber. The heat generated by the exothermic reaction of the resin is not adequately removed; the increase in the temperature at the center increases the resins rate reaction, which in turn generates more heat.

  17. Curing potential of experimental resin composites with systematically varying amount of bioactive glass: Degree of conversion, light transmittance and depth of cure.

    Science.gov (United States)

    Par, Matej; Spanovic, Nika; Bjelovucic, Ruza; Skenderovic, Hrvoje; Gamulin, Ozren; Tarle, Zrinka

    2018-06-17

    The aim of this work was to investigate the curing potential of an experimental resin composite series with the systematically varying amount of bioactive glass 45S5 by evaluating the degree of conversion, light transmittance and depth of cure. Resin composites based on a Bis-GMA/TEGDMA resin with a total filler load of 70 wt% and a variable amount of bioactive glass (0-40 wt%) were prepared. The photoinitiator system was camphorquinone and ethyl-4-(dimethylamino) benzoate. The degree of conversion and light transmittance were measured by Raman spectroscopy and UV-vis spectroscopy, respectively. The depth of cure was evaluated according to the classical ISO 4049 test. The initial introduction of bioactive glass into the experimental series diminished the light transmittance while the further increase in the bioactive glass amount up to 40 wt% caused minor variations with no clear trend. The curing potential of the experimental composites was similar to or better than that of commercial resin composites. However, unsilanized bioactive glass fillers demonstrated the tendency to diminish both the maximum attainable conversion and the curing efficiency at depth. Experimental composite materials containing bioactive glass showed a clinically acceptable degree of conversion and depth of cure. The degree of conversion and depth of cure were diminished by bioactive glass fillers in a dose-dependent manner, although light transmittance was similar among all of the experimental composites containing 5-40 wt% of bioactive glass. Reduced curing potential caused by the bioactive glass has possible consequences on mechanical properties and biocompatibility. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Effect of water curing duration on strength behaviour of portland composite cement (PCC) mortar

    Science.gov (United States)

    Caronge, M. A.; Tjaronge, M. W.; Hamada, H.; Irmawaty, R.

    2017-11-01

    Cement manufacturing of Indonesia has been introduced Portland Composite Cement (PCC) to minimize the rising production cost of cement which contains 80% clinker and 20% mineral admixture. A proper curing is very important when the cement contains mineral admixture materials. This paper reports the results of an experimental study conducted to evaluate the effect of water curing duration on strength behaviour of PCC mortar. Mortar specimens with water to cement ratio of (W/C) 0.5 were casted. Compressive strength, flexural strength and concrete resistance were tested at 7, 28 and 91 days cured water. The results indicated that water curing duration is essential to continue the pozzolanic reaction in mortar which contributes to the development of strength of mortar made with PCC.

  19. Thermal analysis of bulk filled composite resin polymerization using various light curing modes according to the curing depth and approximation to the cavity wall

    Directory of Open Access Journals (Sweden)

    Hoon-Sang Chang

    2013-07-01

    Full Text Available OBJECTIVE: The purpose of this study was to investigate the polymerization temperature of a bulk filled composite resin light-activated with various light curing modes using infrared thermography according to the curing depth and approximation to the cavity wall. MATERIAL AND METHODS: Composite resin (AeliteFlo, Bisco, Schaumburg, IL, USA was inserted into a Class II cavity prepared in the Teflon blocks and was cured with a LED light curing unit (Dr's Light, GoodDoctors Co., Seoul, Korea using various light curing modes for 20 s. Polymerization temperature was measured with an infrared thermographic camera (Thermovision 900 SW/TE, Agema Infra-red Systems AB, Danderyd, Sweden for 40 s at measurement spots adjacent to the cavity wall and in the middle of the cavity from the surface to a 4 mm depth. Data were analyzed according to the light curing modes with one-way ANOVA, and according to curing depth and approximation to the cavity wall with two-way ANOVA. RESULTS: The peak polymerization temperature of the composite resin was not affected by the light curing modes. According to the curing depth, the peak polymerization temperature at the depth of 1 mm to 3 mm was significantly higher than that at the depth of 4 mm, and on the surface. The peak polymerization temperature of the spots in the middle of the cavity was higher than that measured in spots adjacent to the cavity wall. CONCLUSION: In the photopolymerization of the composite resin, the temperature was higher in the middle of the cavity compared to the outer surface or at the internal walls of the prepared cavity.

  20. Flush-mounting technique for composite beams

    Science.gov (United States)

    Harman, T. C.; Kay, B. F.

    1980-01-01

    Procedure permits mounting of heavy parts to surface of composite beams without appreciably weakening beam web. Web is split and held apart in region where attachment is to be made by lightweight precast foam filler. Bolt hole penetrates foam rather than web, and is secured by barrelnut in transverse bushing through web.

  1. Strong composition dependence of adhesive properties of ultraviolet curing adhesives with modified acrylates

    Science.gov (United States)

    Feng, Yefeng; Li, Yandong; Wang, Fupeng; Peng, Cheng; Xu, Zhichao; Hu, Jianbing

    2018-05-01

    Ultraviolet (UV) curable adhesives have been widely researched in fields of health care and electronic components. UV curing systems with modified acrylic ester prepolymers have been frequently employed. In order to clarify composition dependence of adhesive properties of adhesives containing modified acrylates, in this work, several UV curing adhesives bearing urethane and epoxy acrylates were designed and fabricated. The effects of prepolymer, diluent, feed ratio, initiator and assistant on adhesive performances were investigated. This work might offer a facile route to gain promising high-performance UV curable adhesives with desired adhesive traits through regulating their compositions.

  2. Development of a Fully Automated Guided Wave System for In-Process Cure Monitoring of CFRP Composite Laminates

    Science.gov (United States)

    Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.; Yaun, Fuh-Gwo

    2016-01-01

    A guided wave-based in-process cure monitoring technique for carbon fiber reinforced polymer (CFRP) composites was investigated at NASA Langley Research Center. A key cure transition point (vitrification) was identified and the degree of cure was monitored using metrics such as amplitude and time of arrival (TOA) of guided waves. Using an automated system preliminarily developed in this work, high-temperature piezoelectric transducers were utilized to interrogate a twenty-four ply unidirectional composite panel fabricated from Hexcel (Registered Trademark) IM7/8552 prepreg during cure. It was shown that the amplitude of the guided wave increased sharply around vitrification and the TOA curve possessed an inverse relationship with degree of cure. The work is a first step in demonstrating the feasibility of transitioning the technique to perform in-process cure monitoring in an autoclave, defect detection during cure, and ultimately a closed-loop process control to maximize composite part quality and consistency.

  3. The effect of time between curing and tea immersion on composite resin discoloration.

    Science.gov (United States)

    Esmaeili, Behnaz; Afkhami, Solaleh; Abolghasemzadeh, Faezeh

    2018-01-01

    One common cause for the replacement of a composite restoration is discoloration. This in vitro study evaluated the effect of tea solution on the discoloration of 3 types of composites at different timepoints after curing. For this study, 150 disc-shaped specimens of 3 types of composite resin-a nanohybrid (Filtek Z350), a microhybrid (Filtek Z250), and a microfilled material (Heliomolar)-were prepared. Specimens were randomly divided into 5 subgroups (n = 10) according to the type of composite and the time from curing to immersion in a tea solution (none [immersed immediately], 1 hour, 6 hours, 12 hours, or 24 hours postcuring). The color for all specimens was measured before and after immersion in tea. Color change (ΔE*) for all specimens was measured, and a ΔE* value of less than 3.3 was considered clinically acceptable. Analysis of variance and a post hoc Tukey test were used to analyze the data (α = 0.05). Immediately after curing, the levels of composite discoloration were deemed clinically acceptable (ΔE* composites, the greatest color change was found immediately after curing (P composite resin specimens was significantly greater than that of Heliomolar specimens (P composite group than in the Heliomolar group (P composites were not significantly different from each other (P > 0.05), except with 12-hour postcure immersion. The results suggest that patients should avoid the intake of staining foods or beverages for at least 12 hours after placement of a composite resin restoration, although this restriction may be reduced to 1 hour for microfilled composite resins.

  4. Mechanical and Thermal Properties of Dental Composites Cured with CAD/CAM Assisted Solid-State Laser

    Directory of Open Access Journals (Sweden)

    Roberto De Santis

    2018-03-01

    Full Text Available Over the last three decades, it has been frequently reported that the properties of dental restorative composites cured with argon laser are similar or superior to those achieved with conventional halogen and light emitting diode (LED curing units. Whereas laser curing is not dependent on the distance between the curing unit and the material, such distance represents a drawback for conventional curing units. However, a widespread clinical application of this kind of laser remains difficult due to cost, heavy weight, and bulky size. Recently, with regard to the radiation in the blue region of the spectrum, powerful solid-state lasers have been commercialized. In the current research, CAD (computer-aided design/CAM (computer-aided manufacturing assisted solid-state lasers were employed for curing of different dental restorative composites consisting of micro- and nanoparticle-reinforced materials based on acrylic resins. Commercial LED curing units were used as a control. Temperature rise during the photopolymerisation process and bending properties were measured. By providing similar light energy dose, no significant difference in temperature rise was observed when the two light sources provided similar intensity. In addition, after 7 days since curing, bending properties of composites cured with laser and LED were similar. The results suggested that this kind of laser would be suitable for curing dental composites, and the curing process does not suffer from the tip-to-tooth distance.

  5. Mechanical and Thermal Properties of Dental Composites Cured with CAD/CAM Assisted Solid-State Laser

    Science.gov (United States)

    De Santis, Roberto; Gloria, Antonio; Maietta, Saverio; Martorelli, Massimo; De Luca, Alessandro; Spagnuolo, Gianrico; Riccitiello, Francesco; Rengo, Sandro

    2018-01-01

    Over the last three decades, it has been frequently reported that the properties of dental restorative composites cured with argon laser are similar or superior to those achieved with conventional halogen and light emitting diode (LED) curing units. Whereas laser curing is not dependent on the distance between the curing unit and the material, such distance represents a drawback for conventional curing units. However, a widespread clinical application of this kind of laser remains difficult due to cost, heavy weight, and bulky size. Recently, with regard to the radiation in the blue region of the spectrum, powerful solid-state lasers have been commercialized. In the current research, CAD (computer-aided design)/CAM (computer-aided manufacturing) assisted solid-state lasers were employed for curing of different dental restorative composites consisting of micro- and nanoparticle-reinforced materials based on acrylic resins. Commercial LED curing units were used as a control. Temperature rise during the photopolymerisation process and bending properties were measured. By providing similar light energy dose, no significant difference in temperature rise was observed when the two light sources provided similar intensity. In addition, after 7 days since curing, bending properties of composites cured with laser and LED were similar. The results suggested that this kind of laser would be suitable for curing dental composites, and the curing process does not suffer from the tip-to-tooth distance. PMID:29584683

  6. Simultaneous measurement of polymerization stress and curing kinetics for photo-polymerized composites with high filler contents.

    Science.gov (United States)

    Wang, Zhengzhi; Landis, Forrest A; Giuseppetti, Anthony A M; Lin-Gibson, Sheng; Chiang, Martin Y M

    2014-12-01

    Photopolymerized composites are used in a broad range of applications with their performance largely directed by reaction kinetics and contraction accompanying polymerization. The present study was to demonstrate an instrument capable of simultaneously collecting multiple kinetics parameters for a wide range of photopolymerizable systems: degree of conversion (DC), reaction exotherm, and polymerization stress (PS). Our system consisted of a cantilever beam-based instrument (tensometer) that has been optimized to capture a large range of stress generated by lightly-filled to highly-filled composites. The sample configuration allows the tensometer to be coupled to a fast near infrared (NIR) spectrometer collecting spectra in transmission mode. Using our instrument design, simultaneous measurements of PS and DC are performed, for the first time, on a commercial composite with ≈80% (by mass) silica particle fillers. The in situ NIR spectrometer collects more than 10 spectra per second, allowing for thorough characterization of reaction kinetics. With increased instrument sensitivity coupled with the ability to collect real time reaction kinetics information, we show that the external constraint imposed by the cantilever beam during polymerization could affect the rate of cure and final degree of polymerization. The present simultaneous measurement technique is expected to provide new insights into kinetics and property relationships for photopolymerized composites with high filler content such as dental restorative composites. Published by Elsevier Ltd.

  7. Marginal integrity of resin composite restorations restored with PPD initiatorcontaining resin composite cured by QTH, monowave and polywave LED units.

    Science.gov (United States)

    Bortolotto, Tissiana; Betancourt, Francisco; Krejci, Ivo

    2016-12-01

    This study evaluated the influence of curing devices on marginal adaptation of cavities restored with self-etching adhesive containing CQ and PPD initiators and hybrid composite. Twenty-four class V (3 groups, n=8) with margins located on enamel and dentin were restored with Clearfil S3 Bond and Clearfil APX PLT, light-cured with a monowave LED, multiwave LED and halogen light-curing unit (LCU). Marginal adaptation was evaluated with SEM before/after thermo-mechanical loading (TML). On enamel, significantly lower % continuous margins (74.5±12.6) were found in group cured by multiwave LED when compared to monowave LED (87.6±9.5) and halogen LCU (94.4±9.1). The presence of enamel and composite fractures was significantly higher in the group light-cured with multiwave LED, probably due to an increased materials' friability resulted from an improved degree of cure. The clinician should aware that due to a distinct activation of both initiators, marginal quality may be influenced on the long-term.

  8. Gravity Effects of Curing Angle on Laminated Composite Structures: A Review on Novel Study

    Directory of Open Access Journals (Sweden)

    T. T. T. Jennise

    2013-01-01

    Full Text Available Composites manufactured by small and medium industries/entrepreneurs (SMI/E are conventionally cured in the horizontal position. Hence, the confined space restricts optimum productivity. Besides, SMI/E is unable to allocate high budget for high-end technology such as autoclave and vacuum mechanical oven which limits the development of SMI/E as a result of high capital cost. Through a series of literature review, the review confirmed that there is no similar scientific study has been conducted. Consequently, the review is carried out to facilitate the investigation of the feasibility of a gravity cured glass fiber laminated thermosetting composites via vacuum bagging at angle position from horizontal (0° to vertical (90° to enhance the curing space required.

  9. Influence of the curing cycles on the fatigue performance of unidirectional glass fiber reinforced epoxy composites

    DEFF Research Database (Denmark)

    Hüther, Jonas; Brøndsted, Povl

    2016-01-01

    During the manufacturing process of fiber reinforced polymers the curing reaction of the resin results in shrinkage of the resin and introduces internal stresses in the composites. When curing at higher temperatures in order to shorten up the processing time, higher curing stresses and thermal...... to different levels of internal stresses. The mechanical properties, static strength and fatigue life time, are measured in three different directions of the material, i.e. the fiber direction, 0°, the 30° off axis direction, and the 90° direction transverse to the fiber direction. It is experimentally...... demonstrated that the resulting residual stresses barely influences the quasi-static mechanical properties of reinforced glass-fiber composites. It is found that the fatigue performance in the 0° direction is significantly influenced by the internal stresses, whereas the fatigue performance in the off axes...

  10. Optimal cure cycle design of a resin-fiber composite laminate

    Science.gov (United States)

    Hou, Jean W.; Sheen, Jeenson

    1987-01-01

    A unified computed aided design method was studied for the cure cycle design that incorporates an optimal design technique with the analytical model of a composite cure process. The preliminary results of using this proposed method for optimal cure cycle design are reported and discussed. The cure process of interest is the compression molding of a polyester which is described by a diffusion reaction system. The finite element method is employed to convert the initial boundary value problem into a set of first order differential equations which are solved simultaneously by the DE program. The equations for thermal design sensitivities are derived by using the direct differentiation method and are solved by the DE program. A recursive quadratic programming algorithm with an active set strategy called a linearization method is used to optimally design the cure cycle, subjected to the given design performance requirements. The difficulty of casting the cure cycle design process into a proper mathematical form is recognized. Various optimal design problems are formulated to address theses aspects. The optimal solutions of these formulations are compared and discussed.

  11. Influence of amine structure on the post-cured photo-yellowing of novel amine diacrylate terminated ultraviolet and electron beam cured coatings

    International Nuclear Information System (INIS)

    Allen, N.S.; Lo, D.

    1990-01-01

    The post ultraviolet (UV) and electron beam (EB) cured photo-yellowing of nine novel amine terminated diacrylate monomers has been compared with that of standard commercial diethylamine diacrylate monomer using second order derivative UV absorption spectroscopy. Whilst all the UV cured monomers exhibited an initial rapid growth in UV absorption followed by a rapid photo-bleaching, the EB cured monomers exhibited a very slow growth in absorption followed by a plateau and subsequent slow photo-bleaching. In the former case the residual benzophenone photo-initiator is sensitising the photo-yellowing reaction and its subsequent photo-bleaching. Differences in the rates may be determined by the nature of the exciplex between the terminal amine groups and the benzophenone initiator. With regard to the nature of the amine structure all the simple alkylamines exhibit the greatest degree of photo-yellowing whilst hydroxyl containing amines are generally lower. In the former case methylene hydrogen atoms alpha to the nitrogen atom are important for abstraction. Dicyclohexylamine provides the most stable monomer toward photo-yellowing due to the stability of the alpha methylene hydrogen atoms and steric hindrance by the two bulky cyclohexane rings towards the formation of conjugated chromophores. For the EB cured monomers the degree of photo-yellowing increases with increasing alkyl chain length of the amine group due to the increased possibility of the formation of conjugated chromophores. (author)

  12. Evaluation of wear rate of dental composites polymerized by halogen or LED light curing units

    Directory of Open Access Journals (Sweden)

    Alaghehmand H.

    2006-08-01

    Full Text Available Background and Aim: Sufficient polymerization is a critical factor to obtain optimum physical properties and clinical efficacy of resin restorations. The aim of this study was to evaluate wear rates of composite resins polymerized by two different systems Light Emitting Diodes (LED to and Halogen lamps. Materials and Methods: In this laboratory study, 20 specimens of A3 Tetric Ceram composite were placed in brass molds of 2*10*10 mm dimensions and cured for 40 seconds with 1 mm distance from surface. 10 specimens were cured with LED and the other 10 were cured with Halogen unit. A device with the ability to apply force was developed in order to test the wear of composites. After storage in distilled water for 10 days, the specimens were placed in the wear testing machine. A chrome cobalt stylus with 1.12 mm diameter was applied against the specimens surfaces with a load of 2 kg. The weight of each samples before and after 5000, 10000, 20000, 40000, 80000 and 120000 cycles was measured using an electronic balance with precision of 10-4 grams. Data were analyzed using t test and paired t test. P0.05. Conclusion: Based on the results of this study, LED and halogen light curing units resulted in a similar wear rate in composite resin restorations.

  13. Beam radiation curing of adhesives for flocking on heat-sensitive substrates

    International Nuclear Information System (INIS)

    Nablo, S.V.; Fussa, A.D.

    1979-01-01

    A process is described for curing the adhesive used to hold flock fiber material to a heat-sensitive substrate consisting of temperature-sensitive plastic, natural fibers, wood, paper, or paper-foil laminates. An electron-curable adhesive layer (acrylic, epoxy, epoxy esters, acrylic latex, or urethane) a few mils thick is applied to the substrate and a layer of texturing material is attached to the adhesive layer with fibers substantially perpendicular to the layer. The assembly of substrate and adhesively secured material is passed at a rate of about 20 to 80 meters per minute under an unscanned electron curtain beam which possesses an energy of 150 keV +- 30 percent and delivers an electron dose of 2 megarads +- 50 percent to the adhesive layer. (LL)

  14. Composite Cure Process Modeling and Simulations using COMPRO(Registered Trademark) and Validation of Residual Strains using Fiber Optics Sensors

    Science.gov (United States)

    Sreekantamurthy, Thammaiah; Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.

    2016-01-01

    Composite cure process induced residual strains and warping deformations in composite components present significant challenges in the manufacturing of advanced composite structure. As a part of the Manufacturing Process and Simulation initiative of the NASA Advanced Composite Project (ACP), research is being conducted on the composite cure process by developing an understanding of the fundamental mechanisms by which the process induced factors influence the residual responses. In this regard, analytical studies have been conducted on the cure process modeling of composite structural parts with varied physical, thermal, and resin flow process characteristics. The cure process simulation results were analyzed to interpret the cure response predictions based on the underlying physics incorporated into the modeling tool. In the cure-kinetic analysis, the model predictions on the degree of cure, resin viscosity and modulus were interpreted with reference to the temperature distribution in the composite panel part and tool setup during autoclave or hot-press curing cycles. In the fiber-bed compaction simulation, the pore pressure and resin flow velocity in the porous media models, and the compaction strain responses under applied pressure were studied to interpret the fiber volume fraction distribution predictions. In the structural simulation, the effect of temperature on the resin and ply modulus, and thermal coefficient changes during curing on predicted mechanical strains and chemical cure shrinkage strains were studied to understand the residual strains and stress response predictions. In addition to computational analysis, experimental studies were conducted to measure strains during the curing of laminated panels by means of optical fiber Bragg grating sensors (FBGs) embedded in the resin impregnated panels. The residual strain measurements from laboratory tests were then compared with the analytical model predictions. The paper describes the cure process

  15. Effect of dual-cure composite resin as restorative material on marginal adaptation of class 2 restorations.

    Science.gov (United States)

    Bortolotto, Tissiana; Melian, Karla; Krejci, Ivo

    2013-10-01

    The present study attempted to find a simple direct adhesive restorative technique for the restoration of Class 2 cavities. A self-etch adhesive system with a dual-cured core buildup composite resin (paste 1 + paste 2) was evaluated in its ability to restore proximo-occlusal cavities with margins located on enamel and dentin. The groups were: A, cavity filling (cf) with paste 1 (light-curing component) by using a layering technique; B, cf by mixing both pastes, bulk insertion, and dual curing; and C, cf by mixing both pastes, bulk insertion, and chemical curing. Two control groups (D, negative, bulk; and E, positive, layering technique) were included by restoring cavities with a classic three-step etch-and-rinse adhesive and a universal restorative composite resin. SEM margin analysis was performed before and after thermomechanical loading in a chewing simulator. Percentages (mean ± SD) of "continuous margins" were improved by applying the material in bulk and letting it self cure (54 ± 6) or dual cure (59 ± 9), and no significant differences were observed between these two groups and the positive control (44 ± 19). The present study showed that the dual-cured composite resin tested has the potential to be used as bulk filling material for Class 2 restorations. When used as filling materials, dual-cure composite resins placed in bulk can provide marginal adaptation similar to light-cured composites applied with a complex stratification technique.

  16. Failure modes of composite sandwich beams

    OpenAIRE

    Gdoutos E.; Daniel I.M.

    2008-01-01

    A thorough investigation of failure behavior of composite sandwich beams under three-and four-point bending was undertaken. The beams were made of unidirectional carbon/epoxy facings and a PVC closed-cell foam core. The constituent materials were fully characterized and in the case of the foam core, failure envelopes were developed for general two-dimensional states of stress. Various failure modes including facing wrinkling, indentation failure and core failure were observed and compared wit...

  17. A Refined Zigzag Beam Theory for Composite and Sandwich Beams

    Science.gov (United States)

    Tessler, Alexander; Sciuva, Marco Di; Gherlone, Marco

    2009-01-01

    A new refined theory for laminated composite and sandwich beams that contains the kinematics of the Timoshenko Beam Theory as a proper baseline subset is presented. This variationally consistent theory is derived from the virtual work principle and employs a novel piecewise linear zigzag function that provides a more realistic representation of the deformation states of transverse-shear flexible beams than other similar theories. This new zigzag function is unique in that it vanishes at the top and bottom bounding surfaces of a beam. The formulation does not enforce continuity of the transverse shear stress across the beam s cross-section, yet is robust. Two major shortcomings that are inherent in the previous zigzag theories, shear-force inconsistency and difficulties in simulating clamped boundary conditions, and that have greatly limited the utility of these previous theories are discussed in detail. An approach that has successfully resolved these shortcomings is presented herein. Exact solutions for simply supported and cantilevered beams subjected to static loads are derived and the improved modelling capability of the new zigzag beam theory is demonstrated. In particular, extensive results for thick beams with highly heterogeneous material lay-ups are discussed and compared with corresponding results obtained from elasticity solutions, two other zigzag theories, and high-fidelity finite element analyses. Comparisons with the baseline Timoshenko Beam Theory are also presented. The comparisons clearly show the improved accuracy of the new, refined zigzag theory presented herein over similar existing theories. This new theory can be readily extended to plate and shell structures, and should be useful for obtaining relatively low-cost, accurate estimates of structural response needed to design an important class of high-performance aerospace structures.

  18. Influence of aromatic amine hardeners in the cure kinetics of an epoxy resin used in advanced composites

    Directory of Open Access Journals (Sweden)

    Michelle Leali Costa

    2005-03-01

    Full Text Available Composite structures for aerospace applications are mainly made by the well-known prepreg technology. In order to achieve adequate prepreg processing schedules, and consequently maximum fiber strength utilization, one has to know in deep the cure kinetics of matrix, which held the fibers together. This work describes a procedure to study the cure kinetic and has as example how aromatic amine hardeners influence the cure kinetics of an epoxy resin used in advanced composites. The investigation was carried out by using the DSC technique and it was found that depending on the system used the cure kinetics of the formulation obeys order n or autocatalytic order.

  19. Effect of different light curing units on Knoop hardness and temperature of resin composite.

    Science.gov (United States)

    Guiraldo, Ricardo Danil; Consani, Simonides; Xediek Consani, Rafael Leonardo; Mendes, Wilson Batista; Lympius, Thais; Coelho Sinhoreti, Mario Alexandre

    2009-01-01

    To evaluate the influence of quartz tungsten halogen and plasma arc curing (PAC) lights on Knoop hardness and change in polymerization temperature of resin composite. Filtek Z250 and Esthet X composites were used in the shade A3. The temperature increase was registered with Type-k thermocouple connected to a digital thermometer (Iopetherm 46). A self-cured polymerized acrylic resin base was built in order to guide the thermocouple and to support the dentin disk of 1.0 mm thickness obtained from bovine tooth. On the acrylic resin base, elastomer mold of 2.0 mm was adapted. The temperature increase was measured after composite light curing. After 24 h, the specimens were submitted to Knoop hardness test (HMV-2000, Shimadzu, Tokyo, Japan). Data were submitted to ANOVA and Tukey's test (alpha = 0.05). For both composites, there were no significant differences (P > 0.05) in the top surface hardness; however, PAC promoted statistically lower (P 0.05). The standardized radiant exposure showed no influence on the temperature increase of the composite, however, showed significant effect on hardness values.

  20. Effect of different light curing units on Knoop hardness and temperature of resin composite

    Directory of Open Access Journals (Sweden)

    Guiraldo Ricardo

    2009-01-01

    Full Text Available Aim: To evaluate the influence of quartz tungsten halogen and plasma arc curing (PAC lights on Knoop hardness and change in polymerization temperature of resin composite. Materials and Methods: Filtek Z250 and Esthet X composites were used in the shade A3. The temperature increase was registered with Type-k thermocouple connected to a digital thermometer (Iopetherm 46. A self-cured polymerized acrylic resin base was built in order to guide the thermocouple and to support the dentin disk of 1.0 mm thickness obtained from bovine tooth. On the acrylic resin base, elastomer mold of 2.0 mm was adapted. The temperature increase was measured after composite light curing. After 24 h, the specimens were submitted to Knoop hardness test (HMV-2000, Shimadzu, Tokyo, Japan. Data were submitted to ANOVA and Tukey′s test (a = 0.05. Results: For both composites, there were no significant differences (P > 0.05 in the top surface hardness; however, PAC promoted statistically lower (P < 0.05 Knoop hardness number values in the bottom. The mean temperature increase showed no significant statistical differences (P > 0.05. Conclusion: The standardized radiant exposure showed no influence on the temperature increase of the composite, however, showed significant effect on hardness values.

  1. Effects on microstrain and conversion of flowable resin composite using different curing modes and units.

    Science.gov (United States)

    Tseng, Wan-Yu; Chen, Ruey-Song; Wang, Jaw-Lin; Lee, Ming-Shu; Rueggeberg, Frederick A; Chen, Min-Huey

    2007-05-01

    The flowable resin composite, Tetric Flow, was used to measure microstrain and degree of conversion after hardening with each of three curing machines: XL3000(XL) for 10, 20, 30, and 40 s; Optilux 501 using conventional mode (OC) for 10, 20, 30, and 40 s, as well as Optilux boost (OB, 10 s) and ramp modes (OR, 20 s); and LEDemetron (LEDe) for 10, 20, 30, and 40 s. The emitted power density and spectral distribution of the three light curing units were also measured. The LEDe output energy spectrum was centralized between 425 and 490 nm, which encompasses the excited wavelength of camphorquinone. The microstrain produced by the curing process is as a second-degree polynomial for each light source. The OB microstrain was highest, while the OR microstrain was lower. The ranking in order of degree of monomer conversion was as follows: XL10 conversion cured with OB was significant higher than other curing modes except OC30, OC40, LEDe30, LEDe40, and XL40. The conversion value of XL10 was the lowest. The LEDe produced higher conversion for the same emitted energy compared to the two halogen units.

  2. Cuspal Flexure and Extent of Cure of a Bulk-fill Flowable Base Composite.

    Science.gov (United States)

    Francis, A V; Braxton, A D; Ahmad, W; Tantbirojn, D; Simon, J F; Versluis, A

    2015-01-01

    To investigate a bulk-fill flowable base composite (Surefil SDR Flow) in terms of cuspal flexure and cure when used in incremental or bulk techniques. Mesio-occluso-distal cavities (4 mm deep, 4 mm wide) were prepared in 24 extracted molars. The slot-shaped cavities were etched, bonded, and restored in 1) two 2-mm increments Esthet-X HD (control), 2) two 2-mm increments Surefil SDR Flow, or 3) 4-mm bulk Surefil SDR Flow (N=8). The teeth were digitized after preparation (baseline) and restoration and were precisely aligned to calculate cuspal flexure. Restored teeth were placed in fuchsin dye for 16 hours to determine occlusal bond integrity from dye penetration. Extent of cure was assessed by hardness at 0.5-mm increments through the restoration depth. Results were analyzed with analysis of variance and Student-Newman-Keuls post hoc tests (α=0.05). Surefil SDR Flow, either incrementally or bulk filled, demonstrated significantly less cuspal flexure than Esthet-X HD. Dye penetration was less than 3% of cavity wall height and was not statistically different among groups. The hardness of Surefil SDR Flow did not change throughout the depth for both incrementally and bulk filled restorations; the hardness of Esthet-X HD was statistically significantly lower at the bottom of each increment than at the top. Filling in bulk or increments made no significant difference in marginal bond quality or cuspal flexure for the bulk-fill composite. However, the bulk-fill composite caused less cuspal flexure than the incrementally placed conventional composite. The bulk-fill composite cured all the way through (4 mm), whereas the conventional composite had lower cure at the bottom of each increment.

  3. E-Beam-Cured Layered-Silicate and Spherical Silica Epoxy Nanocomposites (Preprint)

    National Research Council Canada - National Science Library

    Chen, Chenggang; Anderson, David P

    2007-01-01

    .... The nanofillers can be two dimensional (layered-silicate) and zero dimensional (spherical silica). Both the spherical silica epoxy nanocomposite and the layered-silicate epoxy nanocomposite can be cured to a high degree of curing...

  4. Mechanical properties and polymerization shrinkage of composite resins light-cured using two different lasers.

    Science.gov (United States)

    Kim, Tae-Wan; Lee, Jang-Hoon; Jeong, Seung-Hwa; Ko, Ching-Chang; Kim, Hyung-Il; Kwon, Yong Hoon

    2015-04-01

    The purpose of the present study was to investigate the usefulness of 457 and 473 nm lasers for the curing of composite resins during the restoration of damaged tooth cavity. Monochromaticity and coherence are attractive features of laser compared with most other light sources. Better polymerization of composite resins can be expected. Eight composite resins were light cured using these two lasers and a light-emitting diode (LED) light-curing unit (LCU). To evaluate the degrees of polymerization achieved, polymerization shrinkage and flexural and compressive properties were measured and compared. Polymerization shrinkage values by 457 and 473 nm laser, and LED ranged from 10.9 to 26.8, from 13.2 to 26.1, and from 11.5 to 26.3 μm, respectively. The values by 457 nm laser was significantly different from those by 473 and LED LCU (p0.05). For the tested LCUs, no specific LCU could consistently achieve highest strength and modulus from the specimens tested. Two lasers (457 and 473 nm) can polymerize composite resins to the level that LED LCU can achieve despite inconsistent trends of polymerization shrinkage and flexural and compressive properties of the tested specimens.

  5. Effect of preheating and light-curing unit on physicochemical properties of a bulk fill composite

    Directory of Open Access Journals (Sweden)

    Theobaldo JD

    2017-05-01

    Full Text Available Jéssica Dias Theobaldo,1 Flávio Henrique Baggio Aguiar,1 Núbia Inocencya Pavesi Pini,2 Débora Alves Nunes Leite Lima,1 Priscila Christiane Suzy Liporoni,3 Anderson Catelan3 1Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, 2Ingá University Center, Maringá, 3Departament of Dentistry, University of Taubaté, Taubaté, Brazil Objective: The aim of this study is to evaluate the effect of composite preheating and polymerization mode on degree of conversion (DC, microhardness (KHN, plasticization (P, and depth of polymerization (DP of a bulk fill composite.Methods: Forty disc-shaped samples (n = 5 of a bulk fill composite were prepared (5 × 4 mm thick and randomly divided into 4 groups according to light-curing unit (quartz–tungsten–halogen [QTH] or light-emitting diode [LED] and preheating temperature (23 or 54 °C. A control group was prepared with a flowable composite at room temperature. DC was determined using a Fourier transform infrared spectrometer, KHN was measured with a Knoop indenter, P was evaluated by percentage reduction of hardness after 24 h of ethanol storage, and DP was obtained by bottom/top ratio. Data were statistically analyzed by analysis of variance and Tukey’s test (α = 0.05.Results: Regardless of light-curing, the highest preheating temperature increased DC compared to room temperature on bottom surface. LED showed a higher DC compared to QTH. Overall, DC was higher on top surface than bottom. KHN, P, and DP were not affected by curing mode and temperature, and flowable composite showed similar KHN, and lower DC and P, compared to bulk fill.Conclusion: Composite preheating increased the polymerization degree of 4-mm-increment bulk fill, but it led to a higher plasticization compared to the conventional flowable composite evaluated. Keywords: composite resins, physicochemical phenomena, polymerization, hardness, heating

  6. [Effect of thermal cycling on surface microstructure of different light-curing composite resins].

    Science.gov (United States)

    Lv, Da; Liu, Kai-Lei; Yao, Yao; Zhang, Wei-Sheng; Liao, Chu-Hong; Jiang, Hong

    2015-04-01

    To evaluate the effect of thermal cycling on surface microstructure of different light-curing composite resins. A nanofilled composite (Z350) and 4 microhybrid composites (P60, Z250, Spectrum, and AP-X) were fabricated from lateral to center to form cubic specimens. The lateral surfaces were abrased and polished before water storage and 40 000 thermal cycles (5/55 degrees celsius;). The mean surface roughness (Ra) were measured and compared before and after thermal cycling, and the changes of microstructure were observed under scanning electron microscope (SEM). Significant decreases of Ra were observed in the composites, especially in Spectrum (from 0.164±0.024 µm to 0.140±0.017 µm, Presins, and fissures occurred on Z350 following the thermal cycling. Water storage and thermal cycling may produce polishing effect on composite resins and cause fissures on nanofilled composite resins.

  7. Influence of Emission Spectrum and Irradiance on Light Curing of Resin-Based Composites.

    Science.gov (United States)

    Shimokawa, Cak; Sullivan, B; Turbino, M L; Soares, C J; Price, R B

    This study examined the influence of different emission spectra (single-peak and broad-spectrum) light-curing units (LCUs) delivering the same radiant exposures at irradiance values of 1200 or 3600 mW/cm 2 on the polymerization and light transmission of four resin-based composites (RBCs). Two prototype LCUs that used the same light tip, but were either a single-peak blue or a broad-spectrum LED, were used to deliver the same radiant exposures to the top surfaces of the RBCs using either standard (1200 mW/cm 2 ) or high irradiance (3600 mW/cm 2 ) settings. The emission spectrum and radiant power from the LCUs were measured with a laboratory-grade integrating sphere coupled to a spectrometer, and the light beam was assessed with a beam profiler camera. Four RBCs (Filtek Supreme Ultra A2, Tetric EvoCeram A2, Tetric EvoCeram T, and TPH Spectra High Viscosity A2) were photoactivated using four different light conditions: single-peak blue/standard irradiance, single-peak blue/high irradiance, broad-spectrum/standard irradiance, and broad-spectrum/high irradiance. The degree of conversion (N=5) and microhardness at the top and bottom of 2.3-mm-diameter by 2.5-mm-thick specimens (N=5) were analyzed with analysis of variance and Tukey tests. The real-time light transmission through the RBCs was also measured. For all light conditions, the 2.3-mm-diameter specimens received a homogeneous irradiance and spectral distribution. Although similar radiant exposures were delivered to the top surfaces of the RBCs, the amount of light energy emitted from the bottom surfaces was different among the four RBCs, and was also greater for the single-peak lights. Very little violet light (wavelengths below 420 nm) reached the bottom of the 2.5-mm-thick specimens. The degree of conversion and microhardness results varied according to the RBC (pspectrum lights, while at the bottom, where little violet light was observed, the results were equal or higher when they were photoactivated with

  8. Dynamic Mechanical Analysis of E-Beam and Thermally Curable IPN Thermosets

    National Research Council Canada - National Science Library

    Jensen, Robert

    2002-01-01

    .... E-beam curing of composites and adhesives offers advantages, such as reduced cure shrinkages, over traditional autoclave processing by curing multiple resins through the thickness for thick-section...

  9. Evaluation of temperature rise with different curing methods and units in two composite resins

    Directory of Open Access Journals (Sweden)

    Tabatabaei M

    2006-01-01

    Full Text Available Background and Aim: The majority of commercial curing units in dentistry are of halogen lamp type. The new polymerizing units such as blue LED are introduced in recent years. One of the important side effects of light curing is the temperature rise in composite resin polymerization which can affect the vitality of tooth pulp. The purpose of this study was to evaluate the temperature rise in two different composite resins during polymerization with halogen lamps and blue LED. Materials and Methods: This experimental study investigated the temperature rise in two different composites (Hybrid, Tetric Ceram/Nanofilled, Filteke Supreme of A2 shade polymerized with two halogen lamps (Coltolux 50, 350 mW/cm2 and Optilux 501 in standard, 820 mW/cm2 and Ramp, 100-1030 mW/cm2 operating modes and one blue LED with the intensity of 620 mW/cm2. Five samples for each group were prepared and temperature rise was monitored using a k-type thermocouple. Data were analyzed by one-way ANOVA, two-way ANOVA and Tukey HSD tests with P<0.05 as the limit of significance. Results: Light curing units and composite resins had statistically significant influence on the temperature rise (p<0.05. Significantly, lower temperature rise occurred in case of illumination with Coltolux 50.There was no significant difference between Optilux 501 in standard curing mode and LED. Tetric Ceram showed higher temperature rise. Conclusion: According to the results of this study the high power halogen lamp and LED could produce significant heat which may be harmful to the dental pulp.

  10. The role of the epoxy resin: Curing agent ratio in composite interfacial strength by single fibre microbond test

    DEFF Research Database (Denmark)

    Minty, Ross; Thomason, James L.; Petersen, Helga Nørgaard

    2015-01-01

    This paper focuses on an investigation into the role of the epoxy resin: curing agent ratio in composite interfacial shear strength of glass fibre composites. The procedure involved changing the percentage of curing agent (Triethylenetetramine [TETA]) used in the mixture with several different...... percentages used, ranging from 4% up to 30%, including the stoichiometric ratio. It was found by using the microbond test, that there may exist a relationship between the epoxy resin to curing agent ratio and the level of adhesion between the reinforcing fibre and the polymer matrix of the composite....

  11. Effect of different curing modes on the degree of conversion and the microhardness of different composite restorations

    Directory of Open Access Journals (Sweden)

    Reem Ali Ajaj

    2015-01-01

    Full Text Available Introduction: This study aims to evaluate the effects of different curing units and modes on the degree of conversion (DC and microhardness (MH of two different resin composites [ESTELITE ∑ QUICK (EQ, and Z350 XT (Z3]. Materials and Methods: One hundred (100 discs of each tested material were made and divided into two subgroups (n = 50 according to the discs′ dimensions: 5 mm diameter × 2 mm thickness, and 2 mm diameter × 2 mm thickness. Each subgroup was further subdivided into the following five classes (n = 10: I cured with halogen light curing-unit; II cured with light-emitting diode (LED unit; III cured with argon laser; IV cured with halogen light-curing unit for 5 s, 10 s rest followed by 20 s curing; and V cured with halogen light-curing unit for 10 s, then 10 s rest, followed by 10 s curing. The first subgroup was tested for MH using the Vickers Microhardness tester and the second subgroup was tested for DC using Fourier transform infrared spectroscopy (FTIR. Data were statistically analyzed using two-way analysis of variance (ANOVA and Tukey′s post hoc test P < 0.05. Results: Specimens in class IV showed the highest mean DC and MH, followed by class III, then class II. Class I showed significantly lower mean values for both DC and MH. On the other hand, Z3 showed statistically significantly higher mean DC and MH than EQ. Conclusion: Although the two tested composites did not perform similarly under the test conditions, curing with halogen unit for 5 s, then 10 s rest, followed by 10 s curing improved the DC and the MH of both the tested materials.

  12. Luting of CAD/CAM ceramic inlays: direct composite versus dual-cure luting cement.

    Science.gov (United States)

    Kameyama, Atsushi; Bonroy, Kim; Elsen, Caroline; Lührs, Anne-Katrin; Suyama, Yuji; Peumans, Marleen; Van Meerbeek, Bart; De Munck, Jan

    2015-01-01

    The aim of this study was to investigate bonding effectiveness in direct restorations. A two-step self-etch adhesive and a light-cure resin composite was compared with luting with a conventional dual-cure resin cement and a two-step etch and rinse adhesive. Class-I box-type cavities were prepared. Identical ceramic inlays were designed and fabricated with a computer-aided design/computer-aided manufacturing (CAD/CAM) device. The inlays were seated with Clearfil SE Bond/Clearfil AP-X (Kuraray Medical) or ExciTE F DSC/Variolink II (Ivoclar Vivadent), each by two operators (five teeth per group). The inlays were stored in water for one week at 37°C, whereafter micro-tensile bond strength testing was conducted. The micro-tensile bond strength of the direct composite was significantly higher than that from conventional luting, and was independent of the operator (P<0.0001). Pre-testing failures were only observed with the conventional method. High-power light-curing of a direct composite may be a viable alternative to luting lithium disilicate glass-ceramic CAD/CAM restorations.

  13. Process Modelling of Curing Process-Induced Internal Stress and Deformation of Composite Laminate Structure with Elastic and Viscoelastic Models

    Science.gov (United States)

    Li, Dongna; Li, Xudong; Dai, Jianfeng

    2018-06-01

    In this paper, two kinds of transient models, the viscoelastic model and the linear elastic model, are established to analyze the curing deformation of the thermosetting resin composites, and are calculated by COMSOL Multiphysics software. The two models consider the complicated coupling between physical and chemical changes during curing process of the composites and the time-variant characteristic of material performance parameters. Subsequently, the two proposed models are implemented respectively in a three-dimensional composite laminate structure, and a simple and convenient method of local coordinate system is used to calculate the development of residual stresses, curing shrinkage and curing deformation for the composite laminate. Researches show that the temperature, degree of curing (DOC) and residual stresses during curing process are consistent with the study in literature, so the curing shrinkage and curing deformation obtained on these basis have a certain referential value. Compared the differences between the two numerical results, it indicates that the residual stress and deformation calculated by the viscoelastic model are more close to the reference value than the linear elastic model.

  14. Electron beam-curing coating for pressed cement roof tiles with high-build and excellent durability

    International Nuclear Information System (INIS)

    Maruyama, Tsutomu; Kiyata, Hiroaki

    1979-01-01

    Thick slate has expanded the demand steadily and spread to whole Japan except the northernmost part as a roof material, because it deals with rain water well, its strength, coldness resistance and endurance are excellent, and it can be worked easily. The ornamental finishing by urethane coating is not satisfactory in view of the improvement of productivity and the measures to pollution as well as the design and color. In order to meet this background, new coating has been sought, and electron beam-curing coating seems to be most suitable to cement roof tiles. The history and the present state of cement roof tiles are explained. About 700 tons/month of the coating for cement roof tiles is used at present, and acryl resin coating occupies about 75%, while urethane resin coating is used in Kyushu relatively more. The urethane coating is applied in shops by electrostatic coating, but the acryl coating is mostly applied in sites after tiling over. Electron beam curing used electron beam of 200 keV, and polymerization starts from the radicals formed through ionization, excitation and neutralization. The features of electron beam-curing coating are good adhesion to roof tiles, keeping luster and endurance to discoloration, strong film and feeling like porcelain, drying at normal temperature, productivity and economy. (J.P.N.)

  15. The chemical composition and compression strengths of refractory ceramics, tested for 3 curing temperatures

    International Nuclear Information System (INIS)

    Wan Khairuddin bin Wan Ali

    1994-01-01

    An investigation was carried out to determine and compile the mechanical strength of a refractory ceramic made of ground fire bricks and refractory fire mortar. Three different compositions were studied for the compression strength and it was found that the composition with 50% fire bricks and 50% fire mortar gives the best mechanical strength. With this composition the maximum failure compression stress is 3.2 MPa. and the Young Modulus is 403.5 MPa. The investigation also shows that the curing temperatures and the composition percentages play an important role in determining the strength of the ceramic. The trend obtained from the investigation shows that there is the possibility that an optimum value of composition percentage exist

  16. Development and Validation of a Constitutive Model for Dental Composites during the Curing Process

    Science.gov (United States)

    Wickham Kolstad, Lauren

    Debonding is a critical failure of a dental composites used for dental restorations. Debonding of dental composites can be determined by comparing the shrinkage stress of to the debonding strength of the adhesive that bonds it to the tooth surface. It is difficult to measure shrinkage stress experimentally. In this study, finite element analysis is used to predict the stress in the composite during cure. A new constitutive law is presented that will allow composite developers to evaluate composite shrinkage stress at early stages in the material development. Shrinkage stress and shrinkage strain experimental data were gathered for three dental resins, Z250, Z350, and P90. Experimental data were used to develop a constitutive model for the Young's modulus as a function of time of the dental composite during cure. A Maxwell model, spring and dashpot in series, was used to simulate the composite. The compliance of the shrinkage stress device was also taken into account by including a spring in series with the Maxwell model. A coefficient of thermal expansion was also determined for internal loading of the composite by dividing shrinkage strain by time. Three FEA models are presented. A spring-disk model validates that the constitutive law is self-consistent. A quarter cuspal deflection model uses separate experimental data to verify that the constitutive law is valid. Finally, an axisymmetric tooth model is used to predict interfacial stresses in the composite. These stresses are compared to the debonding strength to check if the composite debonds. The new constitutive model accurately predicted cuspal deflection data. Predictions for interfacial bond stress in the tooth model compare favorably with debonding characteristics observed in practice for dental resins.

  17. Failure modes of composite sandwich beams

    Directory of Open Access Journals (Sweden)

    Gdoutos E.

    2008-01-01

    Full Text Available A thorough investigation of failure behavior of composite sandwich beams under three-and four-point bending was undertaken. The beams were made of unidirectional carbon/epoxy facings and a PVC closed-cell foam core. The constituent materials were fully characterized and in the case of the foam core, failure envelopes were developed for general two-dimensional states of stress. Various failure modes including facing wrinkling, indentation failure and core failure were observed and compared with analytical predictions. The initiation, propagation and interaction of failure modes depend on the type of loading, constituent material properties and geometrical dimensions.

  18. Large Deformation Dynamic Bending of Composite Beams

    Science.gov (United States)

    Derian, E. J.; Hyer, M. W.

    1986-01-01

    Studies were conducted on the large deformation response of composite beams subjected to a dynamic axial load. The beams were loaded with a moderate eccentricity to promote bending. The study was primarily experimental but some finite element results were obtained. Both the deformation and the failure of the beams were of interest. The static response of the beams was also studied to determine potential differences between the static and dynamic failure. Twelve different laminate types were tested. The beams were loaded dynamically with a gravity driven impactor traveling at 19.6 ft/sec and quasi-static tests were conducted on identical beams in a displacement controlled manner. For laminates of practical interest, the failure modes under static and dynamic loadings were identical. Failure in most of the laminate types occurred in a single event involving 40% to 50% of the plies. However, failure in laminates with 30 deg or 15 deg off-axis plies occured in several events. All laminates exhibited bimodular elastic properties. Using empirically determined flexural properties, a finite element analysis was reasonably accurate in predicting the static and dynamic deformation response.

  19. Effect of zirconium nanoparticles on the mechanical properties of light-cured resin based dental composites

    International Nuclear Information System (INIS)

    Afza, N.; Anis, I.; Aslam, M.; Shah, M.R.; Hussain, M.T.; Bokhari, T.H.; Hussain, A.; Safdar, M.

    2012-01-01

    The aim of this study was to evaluate the mechanical properties of conventional composite resins (Solare-P) and the modified composite resin having mixed with zirconium nanoparticles. The composite resins are used to replace the missing tooth structure and improve esthetics. In this study, the composite was filled with increments in a mould which was 4 mm in depth and 3 mm in diameter. After filling, it was polymerized with halogen light curing unit for 20 seconds for each increment. In other experiments, the composite was mixed with zirconium nanoparticles and filled in the moulds with increments and polymerized for 20 seconds with halogen light curing unit for each increment. After keeping the moulds at 37 deg. C for 24 hours their mechanical properties including compressive force, %age elongation, compressive strength and hardness were evaluated. It was seen that by adding zirconium nanoparticles, compressive force, %age elongation, compressive strength and hardness increased significantly. Thus it was concluded that the new materials are better than the conventional compomers. (author)

  20. New-generation curing units and short irradiation time: the degree of conversion of microhybrid composite resin.

    Science.gov (United States)

    Scotti, Nicolla; Venturello, Alberto; Migliaretti, Giuseppe; Pera, Francesco; Pasqualini, Damiano; Geobaldo, Francesco; Berutti, Elio

    2011-09-01

    This in vitro study investigated the depth of cure of a microhybrid composite resin when cured with reduced times of exposure to three commercially available curing lights. Different sample thicknesses (1, 2, and 3 mm) were light cured in high intensity polymerization mode (2,400 mW/cm² for 5, 10, 15, and 20 seconds; 1,100 mW/cm² for 10, 20, 30, and 40 seconds; and 1,100 mW/cm² for 10, 20, 30, and 40 seconds, respectively). The degree of conversion (%) at the bottom of each sample was measured by Attenuated Total Reflection Fourier Transform Infrared (ATR F-TIR) analysis after each polymerization step. Data were analyzed by ANOVA for repeated measures, showing the degree of conversion was not influenced by the curing light employed (P = .622) but was significantly influenced by the thickness of composite resin (P conversion vs the shorter irradiation time permitted (T1) were not significant among different lamps but were significant among different thicknesses. The depth of cure of microhybrid composite resin appears not to be influenced by the curing light employed. Increased irradiation time significantly increases the degree of conversion. Thickness strongly influences depth of cure.

  1. Effect of different light-curing devices and aging procedures on composite knoop microhardness

    Directory of Open Access Journals (Sweden)

    Fernanda Regina Voltarelli

    2009-12-01

    Full Text Available The aim of this study was to evaluate the effect of light-curing devices (Halogen/HAL, Light Emitting Diodes/LED, Argon Laser/LAS and Plasma Arc/PAC and aging procedures (Mechanical Cycling/MC, Thermal Cycling/TC, Storage/S, MC+TC and MC+TC+S on the micro-hardness of bottom/B and top/T surfaces of 2-mm-high composite resin cylinders. The Knoop microhardness test (25 g, 20 s on both B and T was performed before and after each aging procedure. For B and T, before aging procedures, PAC showed reduced polymerization effectiveness when compared with HAL. In the T, after TC, PAC and LAS had also showed reduced polymerization effectiveness when compared to HAL and LED. For all light-curing devices, MC+TC+S and S affected the Knoop microhardness values. In the B, no difference could be observed among the aging procedures for PAC. From all light-curing units, PAC may have rendered composites of reduced quality and the storage aging procedures were the most harmful to the polymer hardness.

  2. Effect of post-curing treatment on mechanical properties of composite resins.

    Science.gov (United States)

    Almeida-Chetti, Verónica A; Macchi, Ricardo L; Iglesias, María E

    2014-01-01

    The aim of this study is to assess the effect of additional curing procedures on the flexural strength and modulus of elasticity of indirect and direct composite materials. Twenty-four rectangular prism-shaped 2 mm x 2 mm x 25 mm samples of Belleglass, Premisa (Kerr), Adoro and Heliomolar (Ivoclar Vivadent) were prepared. Each composite was packed in an ad-hoc stainless steel device with a TeflonR instrument. A mylar strip and a glass slab were placed on top to obtain a flat surface. Polymerization was activated for 20 seconds with a halogen unit (Astralis 10, Ivoclar - Vivadent) with soft start regime and an output with a 350 to 1200 mw/cm2 range at four different points according to the diameter of the end of the guide. The specimens obtained were then randomly divided into two different groups: with and without additional treatment. In the group with additional treatment, the samples adorro were submitted to 25 minutes in Lumamat 100 (Ivoclar Vivadent) and the rest to 20 minutes in BelleGlass HP (Kerr). After the curing procedures, all samples were treated with sandpapers of decreasing grain size under water flow, and stored in distilled water for 24 h. Flexural strength was measured according to the ISO 404920 recommendations and elastic modulus was determined following the procedures of ANSI/ADA standard No. 27. Statistical differences were found among the different materials and curing procedures employed (Pcomposites, and its clinical relevance.

  3. UV curing silicon-containing epoxy resin and its glass cloth reinforced composites

    International Nuclear Information System (INIS)

    Yang Guang; Tang Zhuo; Huang Pengcheng

    2007-01-01

    A UV-curable cationic silicon-containing epoxy resin formulation was developed. The gel conversion of the cured resin after 10-min UV irradiation reached 80% in the presence of 5% diaryliodonium salt photoinitiator and 5.5% polyol chain transfer agent by cationic ring-opening polymerization. The glass cloth-reinforced composites were fabricated with the silicon-containing epoxy resin using the wet lay-up technique and UV irradiation. The mechanical properties of the composites were evaluated. Compared with glass cloth reinforced bisphenol A epoxy resin matrix composites, the silicon-containing epoxy resin matrix composites possessed higher tensile strength and interlayer shear strength which was 158.5MPa and 9.9MPa respectively while other mechanical properties such as flexural property and tensile modulus were similar. (authors)

  4. Controversial effects of fumed silica on the curing and thermomechanical properties of epoxy composites

    Directory of Open Access Journals (Sweden)

    2010-06-01

    Full Text Available The effect of fumed silica on the curing of a trimethylolpropane epoxy resin was investigated by thermal analysis methods like Differential Scanning Calorimetry (DSC, and Dynamic Mechanical Analysis (DMA. The fumed silica used here is a by-product of the silicon and ferrosilicon industry, consisting of micro and nanosized particles. Both the curing reaction and the properties of the obtained composites were affected by the filler content. Different trends were observed for filler contents above and below the 30 wt%. Up to 30 wt%, the behaviour can be explained as a predominantly agglomeration effect. For 30 wt% and higher filler contents, single particles seem to play a more important role.

  5. Fourier transform infrared (FTIR) fiber optic monitoring of composites during cure in an autoclave

    Science.gov (United States)

    Druy, Mark A.; Elandjian, Lucy; Stevenson, William A.; Driver, Richard D.; Leskowitz, Garett M.

    1990-01-01

    Real-time in situ monitoring of the chemical states of epoxy resins was investigated during cure in an autoclave using infrared evanescent spectroscopy. Fiber evanescent sensors were developed which may be sandwiched between the plies of the prepreg sample. A short length of sapphire fiber was used as the sensor cell portion of the fiber probe. Heavy metal fluoride glass optical fiber cables were designed for connecting the FTIR spectrometer to the sensor fiber within the autoclave. The sapphire fibers have outstanding mechanical thermal properties which should permit their use as an embedded link in all thermoset composites. The system is capable of operation at a temperature of 250 C for periods up to 8 hours without major changes to the fiber transmission. A discussion of the selection of suitable sensor fibers, the construction of a fiber-optic interface, and the interpretation of in situ infrared spectra of the curing process is presented.

  6. Curing Pressure Influence of Out-of-Autoclave Processing on Structural Composites for Commercial Aviation

    Directory of Open Access Journals (Sweden)

    Vasileios M. Drakonakis

    2013-01-01

    Full Text Available Autoclaving is a process that ensures the highest quality of carbon fiber reinforced polymer (CFRP composite structures used in aviation. During the autoclave process, consolidation of prepreg laminas through simultaneous elevated pressure and temperature results in a uniform high-end material system. This work focuses on analyzing in a fundamental way the applications of pressure and temperature separately during prepreg consolidation. A controlled pressure vessel (press-clave has been designed that applies pressure during the curing process while the temperature is being applied locally by heat blankets. This vessel gives the ability to design manufacturing processes with different pressures while applying temperature at desired regions of the composite. The pressure role on the curing extent and its effect on the interlayer region are also tested in order to evaluate the consolidation of prepregs to a completely uniform material. Such studies may also be used to provide insight into the morphology of interlayer reinforcement concepts, which are widely used in the featherweight composites. Specimens manufactured by press-clave, which separates pressure from heat, are analytically tested and compared to autoclaved specimens in order to demonstrate the suitability of the press-clave to manufacture high-quality composites with excessively reduced cost.

  7. Correlating cytotoxicity to elution behaviors of composite resins in term of curing kinetic.

    Science.gov (United States)

    Meng, Junquan; Yang, Huichuan; Cao, Man; Li, Lei; Cai, Qing

    2017-09-01

    Cytotoxicity of photocurable composite resins is a key issue for their safe use in dental restoration. Curing kinetic and elution behaviors of the composite resin would have decisive effects on its cytotoxicity. In this study, composite resins composed of bisphenol-glycidyl dimethacrylate (Bis-GMA), triethyleneglycol dimethacrylate (TEGDMA), camphorquinone (CQ), N,N-dimethylaminoethyl methacrylate (DMAEMA) and barium glass powders were prepared by setting the photoinitiators CQ/DMAEMA at 0.5wt%, 1wt% or 3wt% of the total weight of Bis-GMA/TEGDMA. The ratio of Bis-GMA/TEGDMA was 6:4, the ratio of CQ/DMAEMA was 1:1, and the incorporated inorganic powder was 75wt%. Then, curing kinetics were studied by using real-time Fourier transform infrared spectroscopy (FTIR) and photo-DSC (differential scanning calorimeter). Elution behaviors in both ethanol solution and deionized water were monitored by using liquid chromatogram/mass spectrometry (LC/MS). Cytotoxicity was evaluated by in vitro culture of L929 fibroblasts. Finally, they were all analyzed and correlated in terms of initiator contents. It was found that the commonly used 0.5wt% of photoinitiators was somewhat insufficient in obtaining composite resin with low cytotoxicity. Copyright © 2017. Published by Elsevier B.V.

  8. Effect of resin chemistry on depth of cure and cytotoxicity of dental resin composites

    International Nuclear Information System (INIS)

    Susila Anand, V.; Balasubramanian, Venkatesh

    2014-01-01

    Highlights: • Dental composites have differences in polymerization within 2 mm thickness. • Degree of conversion alone may not affect the biocompatibility of composite. • Unreacted double bonds in dental composites may influence biocompatibility. • Magnitude of double bonds depends on the polymerization and chemical composition. • These influence biocompatibility especially if they possess lipophylic properties. -- Abstract: New dental composite restorative materials are being introduced aiming to overcome the disadvantages of contemporary materials. Hence there is a need to analyze the critical properties of these composites to aid in clinical application. This study aims to comparatively analyze the degree of conversion (DC), residual reactivity (DBC/reactivity) and cytotoxicity of 2 composites based on different resin chemistry. Ceram X and Filtek P90 were used in the study to prepare disc shaped samples of 2 mm thickness and 4 mm diameter. The samples for cytotoxicity were cured for 40 s and those of Fourier Transform Infra-red Spectroscopy (FTIR) (DBC/reactivity and DC) for 5 s, 10 s, 20 s and 40 s, at an average intensity of 800 mW/cm 2 with Quartz–Tungsten–Halogen (QTH) light. DC was calculated in 60–100 μm thick and 6 mm diameter samples. Double bonds concentration/reactivity was measured in approximately 80 μm thick sections prepared from the 2 mm thick discs using a hard tissue microtome. The cell viability was scored by Trypan blue exclusion staining technique at 24 h and 48 h. Both composites showed a progressive increase in double bonds/reactivity as the distance from curing probe increased which was inversely proportional to the curing time. The DC of Filtek P90 was 20% and 96% and that of Ceram X 33% and 50% at 5 s and 40 s, respectively. Ceram X showed statistically significantly higher cell viability score at both 24 h and 48 h than Filtek P90. The results were statistically analyzed using non-parametric Kruskal–Wallis, Mann

  9. Effect of resin chemistry on depth of cure and cytotoxicity of dental resin composites

    Energy Technology Data Exchange (ETDEWEB)

    Susila Anand, V. [Rehabilitation Bioengineering Group, Department of Engineering Design, Indian Institute of Technology Madras, Chennai 600036 (India); Department of Conservative Dentistry and Endodontics, Saveetha Dental College, Saveetha University, Chennai 600077 (India); Balasubramanian, Venkatesh, E-mail: chanakya@iitm.ac.in [Rehabilitation Bioengineering Group, Department of Engineering Design, Indian Institute of Technology Madras, Chennai 600036 (India)

    2014-02-15

    Highlights: • Dental composites have differences in polymerization within 2 mm thickness. • Degree of conversion alone may not affect the biocompatibility of composite. • Unreacted double bonds in dental composites may influence biocompatibility. • Magnitude of double bonds depends on the polymerization and chemical composition. • These influence biocompatibility especially if they possess lipophylic properties. -- Abstract: New dental composite restorative materials are being introduced aiming to overcome the disadvantages of contemporary materials. Hence there is a need to analyze the critical properties of these composites to aid in clinical application. This study aims to comparatively analyze the degree of conversion (DC), residual reactivity (DBC/reactivity) and cytotoxicity of 2 composites based on different resin chemistry. Ceram X and Filtek P90 were used in the study to prepare disc shaped samples of 2 mm thickness and 4 mm diameter. The samples for cytotoxicity were cured for 40 s and those of Fourier Transform Infra-red Spectroscopy (FTIR) (DBC/reactivity and DC) for 5 s, 10 s, 20 s and 40 s, at an average intensity of 800 mW/cm{sup 2} with Quartz–Tungsten–Halogen (QTH) light. DC was calculated in 60–100 μm thick and 6 mm diameter samples. Double bonds concentration/reactivity was measured in approximately 80 μm thick sections prepared from the 2 mm thick discs using a hard tissue microtome. The cell viability was scored by Trypan blue exclusion staining technique at 24 h and 48 h. Both composites showed a progressive increase in double bonds/reactivity as the distance from curing probe increased which was inversely proportional to the curing time. The DC of Filtek P90 was 20% and 96% and that of Ceram X 33% and 50% at 5 s and 40 s, respectively. Ceram X showed statistically significantly higher cell viability score at both 24 h and 48 h than Filtek P90. The results were statistically analyzed using non-parametric Kruskal

  10. Radiation curing in the eighties

    International Nuclear Information System (INIS)

    Vrancken, A.

    1984-01-01

    The subject is discussed under the headings: introduction; what is radiation curing; history; radiation curable resins (with properties of products); ultraviolet and electron beam curing; photoinitiation and the ultraviolet light curing process; electron beam curing (initiation; electron beam accelerators); end uses (graphic arts; wood finishing; paper upgrading; adhesives; metal finishing; electronic chemical; floor coatings). (U.K.)

  11. The effect of different light-curing units on fatigue behavior and degree of conversion of a resin composite.

    Science.gov (United States)

    Lohbauer, Ulrich; Rahiotis, Christos; Krämer, Norbert; Petschelt, Anselm; Eliades, George

    2005-07-01

    The aim of this study was to investigate the effect of different light-curing units and irradiation modes on the mechanical fatigue strength and degree of conversion of a restorative resin composite. Conventional halogen, plasma arc and blue LED light-curing units were used for polymerization of a resin composite (Tetric) Ceram, Ivoclar, Vivadent, Liechtenstein). Initial fracture strength (FS) and flexural fatigue limit (FFL) as well as degree of conversion (DC) were measured. The FFL was determined under cyclic loading for 10(5) cycles in terms of a staircase approach. The specimens were stored for 14 days in 37 degrees C distilled water prior to testing. The curing efficiency was observed with Fourier transform infrared micromultiple internal reflectance spectroscopy. The measurements were carried out at 0.5 and 2.5 mm distance from the directly irradiated surface after 14 days storage in dark and dry conditions at 37 degrees C. The highest FS, FFL and DC were observed from high energy curing devices and from extended curing intervals. The conventional halogen light exhibited the most homogenous in-depth curing efficiency along with a low loss of mechanical resistance under cyclic fatigue. Evaluation of flexural fatigue limit and curing efficiency correlate in terms of decreased mechanical strength due to insufficient light-curing intervals or light intensities. Initial promising fracture strengths do not correlate with a clinically more relevant fatigue loading and with the in-depth degree of conversion, both accounting for a significantly reduced strength performance.

  12. Comparison the effect of two types of light curing units with different modes on microleakage of composite filling in Cl II restorations

    Directory of Open Access Journals (Sweden)

    Esmail Yassini

    2017-12-01

    Conclusion: The results showed that both light curing devices were effective and no significant difference between different modes of LED light curing device on microleakage of class II composite restorations was found.

  13. Short communication: pre- and co-curing effect of adhesives on shear bond strengths of composite resins to primary enamel and dentine: an in vitro study.

    Science.gov (United States)

    Viswanathan, R; Shashibhushan, K K; Subba Reddy, V V

    2011-12-01

    To evaluate and compare shear bond strengths of composite resins to primary enamel and dentine when the adhesives are pre-cured (light cured before the application of the resin) or co-cured (adhesive and the resin light cured together). Buccal surfaces of 80 caries-free primary molars were wet ground to create bonding surfaces on enamel and dentine and specimens mounted on acrylic blocks. Two bonding agents (Prime and Bond NT® and Xeno III®) were applied to either enamel or dentine as per manufacturer's instructions. In 40 specimens, the bonding agent was light cured immediately after the application (pre-cured). The other 40 specimens were not light cured until the composite resin application (co-cured). Resin composite cylinders were made incrementally using acrylic moulds over the adhesives and light cured. Specimens were stored in deionised water for 24 hours at room temperature. Shear bond strength was measured using an Instron universal testing machine (in MPa) and was analysed with Student's unpaired t test. Light curing the adhesive separately produced significantly higher bond strengths to primary dentine than co-curing (padhesive separately did not produce significantly different bond strengths to primary enamel (p>0.05). Curing sequence had no significant effect on shear bond strength of adhesives on the primary enamel. Pre-curing adhesives before curing composite resins produced greater shear bond strength to primary dentine.

  14. Low-temperature-cured highly conductive composite of Ag nanowires and polyvinyl alcohol

    International Nuclear Information System (INIS)

    He Song; Zhang Xiang; Yang Bingchu; Xu Xiaomei; Chen Hui; Zhou Conghua

    2017-01-01

    Flexible conductive films were fabricated from a low-temperature-cured, highly conductive composite of silver nanowires (as conducting filler) and polyvinyl alcohol (PVA, as binder). Sheet resistance of 0.12 Ω/sq, conductivity of 2.63×10 4 S/cm, and contact resistance of 1.0 Ω/cm 2 were measured in the films, along with excellent resistance to scratching and good flexibility, making them suitable electrical contact materials for flexible optoelectronic devices. Effects of curing temperature, curing duration, film thickness, and nanowire length on the film’s electrical properties were studied. Due to the abundance of hydroxyl groups on its molecular chains, the addition of PVA improves the film’s flexibility and resistance to scratching. Increased nanowire density and nanowire length benefit film conductance. Monte Carlo simulation was used to further explore the impact of these two parameters on the conductivity. It was observed that longer nanowires produce a higher length-ratio of conducting routes in the networks, giving better film conductivity. (paper)

  15. Curing behaviour of epoxy resin/graphite composites containing ionic liquid

    International Nuclear Information System (INIS)

    Guo Baochun; Wan Jingjing; Lei Yanda; Jia Demin

    2009-01-01

    By adopting the isoconversional method, subtle changes in the curing activation energy (E α ) among epoxy resin/graphite composites by the inclusion of expanded graphite (EG), ionic liquid of 1-butyl-3-methyl-imidazolium hexafluorophosphate ([BMIm]PF 6 ) or their combination are shown in the whole conversion range. At lower concentrations (1 phr) of EG, compared with the E α of the neat epoxy resin, the composite with EG has a lower E α before the gelation, and a higher E α after the gelation. At higher concentrations of EG, however, in the whole conversion range, the composite with EG shows a higher E α compared with the neat epoxy resin. As the curing proceeded, a peculiar increase in E α is found in systems containing [BMIm]PF 6 . Due to the formation of hydrogen bonding between [BMIm]PF 6 and the hardener (Jeffamine), the reactivity of Jeffamine is considerably decreased, leading to a much higher E α in [BMIm]PF 6 -containing systems, especially at higher conversion. In systems containing a combination of [BMIm]PF 6 and EG, due to the interactions between EG and [BMIm]PF 6 , the shielding effect provided by the well-dispersed EG sheets constrains the formation of the hydrogen bonding between [BMIm]PF 6 and Jeffamine, leading to lowered E α compared with that for the system containing [BMIm]PF 6 only.

  16. Effect of light-curing units on microleakage under dental composite resins

    Science.gov (United States)

    Queiroz, R. S.; Bandéca, M. C.; Calixto, L. R.; Saade, E. G.; Nadalin, M. R.; Andrade, M. F.; Porto-Neto, S. T.

    2009-09-01

    The aim of this study was to determine the effect of two light-curing units (QTH and LED) on microleakage of Class II composite resin restorations with dentin cavosurface margins. Twenty extracted mandibular first premolars, free of caries and fractures were prepared two vertical “slot” cavities in the occluso-mesial and -destal surfaces (2 mm buccal-lingually, 2 mm proximal-axially and cervical limit in enamel) and divided into 4 equal groups ( n = 8): GI and GII: packable posterior composite light-activated with LED and QTH, respectively; GIII and GIV: micro-hybrid composite resin light-activated with LED and QTH, respectively. The composite resins were applied following the manufacturer’s instructions. After 24 h of water storage specimens were subjected to thermocycling for a total of 500 cycles at 5 and 55°C and the teeth were then sealed with impermeable material. Teeth were immersed in 0.5% Basic fuchsin during 24 h at room temperature, and zero to three levels of penetration score were attributed. The Mann-Whitney and Kruskal-Wallis tests showed significant statistically similar ( P > 0.05) from GI to GII and GIII to GIV, which the GII (2.750) had the highest mean scores and the GIII and GIV (0.875) had lowest mean scores. The use of different light-curing units has no influence on marginal integrity of Class II composite resin restorations and the proprieties of composite resins are important to reduce the microleakage.

  17. Dielectric analysis of depth dependent curing behavior of dental resin composites.

    Science.gov (United States)

    Steinhaus, Johannes; Moeginger, Bernhard; Grossgarten, Mandy; Rosentritt, Martin; Hausnerova, Berenika

    2014-06-01

    The aim of this study is to investigate depth dependent changes of polymerization process and kinetics of visible light-curing (VLC) dental composites in real-time. The measured quantity - "ion viscosity" determined by dielectric analysis (DEA) - provides the depth dependent reaction rate which is correlated to the light intensity available in the corresponding depths derived from light transmission measurements. The ion viscosity curves of two composites (VOCO Arabesk Top and Grandio) were determined during irradiation of 40s with a light-curing unit (LCU) in specimen depths of 0.5/0.75/1.0/1.25/1.5/1.75 and 2.0mm using a dielectric cure analyzer (NETZSCH DEA 231 with Mini IDEX sensors). The thickness dependent light transmission was measured by irradiation composite specimens of various thicknesses on top of a radiometer setup. The shape of the ion viscosity curves depends strongly on the specimen thickness above the sensor. All curves exhibit a range of linear time dependency of the ion viscosity after a certain initiation time. The determined initiation times, the slopes of the linear part of the curves, and the ion viscosities at the end of the irradiation differ significantly with depth within the specimen. The slopes of the ion viscosity curves as well as the light intensity values decrease with depth and fit to the Lambert-Beer law. The corresponding attenuation coefficients are determined for Arabesk Top OA2 to 1.39mm(-1) and 1.48mm(-1), respectively, and for Grandio OA2 with 1.17 and 1.39mm(-1), respectively. For thicknesses exceeding 1.5mm a change in polymerization behavior is observed as the ion viscosity increases subsequent to the linear range indicating some kind of reaction acceleration. The two VLC composites and different specimen thicknesses discriminate significantly in their ion viscosity evolution allowing for a precise characterization of the curing process even with respect to the polymerization mechanism. Copyright © 2014. Published by

  18. Effect of curing and silanizing on composite repair bond strength using an improved micro-tensile test method.

    Science.gov (United States)

    Eliasson, Sigfus Thor; Dahl, Jon E

    2017-01-01

    Objectives: To evaluate the micro-tensile repair bond strength between aged and new composite, using silane and adhesives that were cured or left uncured when new composite was placed. Methods: Eighty Filtek Supreme XLT composite blocks and four control blocks were stored in water for two weeks and thermo-cycled. Sandpaper ground, etched and rinsed specimens were divided into two experimental groups: A, no further treatment and B, the surface was coated with bis-silane. Each group was divided into subgroups: (1) Adper Scotchbond Multi-Purpose, (2) Adper Scotchbond Multi-Purpose adhesive, (3) Adper Scotchbond Universal, (4) Clearfil SE Bond and (5) One Step Plus. For each adhesive group, the adhesive was (a) cured according to manufacturer's instructions or (b) not cured before repair. The substrate blocks were repaired with Filtek Supreme XLT. After aging, they were serially sectioned, producing 1.1 × 1.1 mm square test rods. The rods were prepared for tensile testing and tensile strength calculated at fracture. Type of fracture was examined under microscope. Results: Leaving the adhesive uncured prior to composite repair placement increased the mean tensile values statistically significant for all adhesives tested, with or without silane pretreatment. Silane surface treatment improved significantly ( p strength values for all adhesives, both for the cured and uncured groups. The mean strength of the control composite was higher than the strongest repair strength ( p strength. Not curing the adhesive before composite placement increased the tensile bond strength.

  19. [Comparison of surface roughness of nanofilled and microhybrid composite resins after curing and polishing].

    Science.gov (United States)

    Jiang, Hong; Lv, Da; Liu, Kailei; Zhang, Weisheng; Yao, Yao; Liao, Chuhong

    2014-05-01

    To compare the surface roughness of nanofilled dental composite resin and microhybrid composite resins after curing and polishing. A nanofilled composite (Z350) and 4 microhybrid composites (P60, Z250, Spectrum, and AP-X) were fabricated from the lateral to the medial layers to prepare 8 mm×8 mm×5 mm cubical specimens. The 4 lateral surfaces of each specimens were polished with abrasive disks (Super-Snap). Profilometer was used to test the mean surface roughness (Ra) after polishing. P60 had the lowest Ra (0.125∓0.030 µm) followed by Z250 and Spectrum. The Ra of Z350 (0.205∓0.052 µm) was greater than that of the other 3 resins, and AP-X had the roughest surfaces. Under scanning electron microscope, the polished faces of P60 resin were characterized by minor, evenly distributed particles with fewer scratches; the polished faces of Z350 presented with scratches where defects of the filling material could be seen. The nanofilled composite Z350 has smooth surface after polishing by abrasive disks, but its smoothness remains inferior to that of other micro-hybrid composite resins.

  20. A One-Component, Fast-Cure, and Economical Epoxy Resin System Suitable for Liquid Molding of Automotive Composite Parts

    Directory of Open Access Journals (Sweden)

    Yiru Wang

    2018-04-01

    Full Text Available Imidazole cured epoxy resin systems were evaluated for one-component, fast-curing resins for liquid molding of automotive composite parts according to industry requirements. It was demonstrated that an epoxy resin-1-(cyanoethyl-2-ethyl-4-methylimidazol(EP-1C2E4MIM system would cure in a few minutes at 120 °C, while exhibiting acceptable pot life, viscosity profiles, and low water absorption. Moreover, this system yielded high Tg parts with mechanical properties similar to the amine-epoxy systems, which are the mainstream two-component epoxy resin systems for automobiles.

  1. Effect of Dose Deposition Profile on E Beam Curing Conversion and Physical Properties of Thick Thermosetting Materials

    International Nuclear Information System (INIS)

    Mommer, C.

    2006-01-01

    Ionizing radiation is currently applied in new curing process for composites with thermosetting matrix bearing vinyl moieties and more generally unsaturations. The high single or multiple dose curing progression of thick samples of acrylate functional oligomers has been investigated by means of Raman microscopy. The Raman microscopy technique allows localized and accurate measurements to reveal the depth conversion profiles. Measurements have been performed on samples treated with increasing doses and with the use of different kinds of high energy electron accelerators available on the market. It was shown that the conversion was not equal thru the samples thickness in all cases, leading to gradient properties in the thermosetting materials which can be of a great importance in composite parts applications. The purpose of these observations has been investigated and it points out the importance of the heat dissipation in the advancement of the polymerisation reaction

  2. Assessment of environmental impact of ultraviolet radiation or electron beam cured print inks on plastic packaging materials

    International Nuclear Information System (INIS)

    Bardi, Marcelo Augusto Goncalves

    2014-01-01

    The high level of pollution generated by the inadequate disposal of polymeric materials has motivated the search for environmentally friendly systems and techniques such as the application of biodegradable polymers and the replacement of the solvent-based paint systems by those with high solids content, based water or cured by radiation, practically free of volatile organic compounds. However, the cured polymer coatings are neither soluble nor molten, increasing the complexity of the reprocessing, recycling and degradation. Thus, this work aimed to develop print inks modified with pro-degrading agents, cured by ultraviolet radiation or electron beam, for printing or decoration in plastic packaging products of short lifetime, which are biodegradable or not. Six coatings (varnish and inks in five colors: yellow, blue, white, black and red), three pro-degrading agents (cobalt stearate, cerium stearate and manganese stearate), five polymeric substrates (Ecobras®, low density polyethylene and its respective modifications with pro-degrading agents). The coatings were applied to the substrates and cured by ultraviolet radiation or electron beam, resulting in 180 samples. These materials were then exposed to accelerated aging chamber, type 'QUV', and composting in natural environment. In order to assess the effects of the polymer coatings on the degradation process of the specimens, only the yellow and black samples were exposed to a controlled composting environment via respirometry, reducing to 16 the number of samples. The organic compound generated by the biodegradation process was analyzed by the ecotoxicity tests. It was observed that the coating layer acted as a barrier that inhibits degradation of the plastic when exposed to weathering. The addition of pro-degrading agents promoted acceleration in the degradation process, promoting the migration of the metal ion to the medium without affecting the final quality of the organic compost. (author)

  3. A Comparison of gel point for a Glass/Epoxy Composite and a Neat Epoxy Material during Isothermal Curing

    DEFF Research Database (Denmark)

    Jakobsen, Johnny; Andreasen, Jens H.; Thomsen, Ole Thybo

    2014-01-01

    Determination of gel point is important for a modelling assessment of residual stresses developed during curing of composite materials. Residual stresses in a composite structure may have a detrimental effect on its mechanical performance and compromise its integrity. In this article, the evoluti...

  4. Effect of Particular Breed on the Chemical Composition, Texture, Color, and Sensorial Characteristics of Dry-cured Ham

    Directory of Open Access Journals (Sweden)

    Pil Nam Seong

    2014-08-01

    Full Text Available The present study demonstrates the impact of specific breed on the characteristics of dry-cured ham. Eighty thighs from Korean native pig (KNP, crossbreed (Landrace×Yorkshire♀×Duroc♂ (LYD, Berkshire (Ber, and Duroc (Du pig breeds (n = 10 for each breed were used for processing of dry-cured ham. The thighs were salted with 6% NaCl (w/w and 100 ppm NaNO2, and total processing time was 413 days. The effects of breed on the physicochemical composition, texture, color and sensory characteristics were assessed on the biceps femoris muscle of the hams. The results revealed that the highest weight loss was found in the dry-cured ham of LYD breed and the lowest weight loss was found in Ber dry-cured ham. The KNP dry-cured ham contain higher intramuscular fat level than other breed hams (p<0.05. It was observed that the dry-cured ham made from KNP breed had the lowest water activity value and highest salt content, while the LYD dry-cure ham had higher total volatile basic nitrogen content than the Ber and Du hams (p<0.05. Zinc, iron and total monounsaturated fatty acids levels were higher in KNP ham while polyunsaturated fatty acids levels were higher in Du ham when compared to other breed hams (p<0.05. Additionally, the KNP dry-cured ham possessed higher Commission International de l’Eclairage (CIE a* value, while the Du dry-cured ham had higher L*, CIE b* and hue angle values (p<0.05. Furthermore, breed significantly affected the sensory attributes of dry-cured hams with higher scores for color, aroma and taste found in KNP dry-cured ham as compared to other breed hams (p<0.05. The overall outcome of the study is that the breed has a potential effect on the specific chemical composition, texture, color and sensorial properties of dry-cured hams. These data could be useful for meat processors to select the suitable breeds for economical manufacturing of high quality dry-cured hams.

  5. Effect of Particular Breed on the Chemical Composition, Texture, Color, and Sensorial Characteristics of Dry-cured Ham.

    Science.gov (United States)

    Seong, Pil Nam; Park, Kuyng Mi; Kang, Sun Moon; Kang, Geun Ho; Cho, Soo Hyun; Park, Beom Young; Van Ba, Hoa

    2014-08-01

    The present study demonstrates the impact of specific breed on the characteristics of dry-cured ham. Eighty thighs from Korean native pig (KNP), crossbreed (Landrace×Yorkshire)♀×Duroc♂ (LYD), Berkshire (Ber), and Duroc (Du) pig breeds (n = 10 for each breed) were used for processing of dry-cured ham. The thighs were salted with 6% NaCl (w/w) and 100 ppm NaNO2, and total processing time was 413 days. The effects of breed on the physicochemical composition, texture, color and sensory characteristics were assessed on the biceps femoris muscle of the hams. The results revealed that the highest weight loss was found in the dry-cured ham of LYD breed and the lowest weight loss was found in Ber dry-cured ham. The KNP dry-cured ham contain higher intramuscular fat level than other breed hams (pham made from KNP breed had the lowest water activity value and highest salt content, while the LYD dry-cure ham had higher total volatile basic nitrogen content than the Ber and Du hams (pham while polyunsaturated fatty acids levels were higher in Du ham when compared to other breed hams (pham possessed higher Commission International de l'Eclairage (CIE) a* value, while the Du dry-cured ham had higher L*, CIE b* and hue angle values (phams with higher scores for color, aroma and taste found in KNP dry-cured ham as compared to other breed hams (pcolor and sensorial properties of dry-cured hams. These data could be useful for meat processors to select the suitable breeds for economical manufacturing of high quality dry-cured hams.

  6. Electron-beam curing of epoxy resins: effect of alcohols on cationic ...

    Indian Academy of Sciences (India)

    Unknown

    Electron-beam (e-beam) induced polymerization of epoxy resins proceeds via cationic mechanism in presence of suitable ... generate ionic species, free radicals, and/or molecules in .... bisphenol A) and the effect of presence of different OH.

  7. Surface Modified Characteristics of the Tetracalcium Phosphate as Light-Cured Composite Resin Fillers

    Directory of Open Access Journals (Sweden)

    Wen-Cheng Chen

    2014-01-01

    Full Text Available The objectives of this study are to characterize the properties of light-cured composite resins that are reinforced with whisker surface-modified particles of tetracalcium phosphate (TTCP and to investigate the influence of thermal cycling on the reinforced composites properties. The characteristics of ultimate diametral tensile strength (DTS, moduli, pH values, and fracture surfaces of the samples with different amounts of surface-modified TTCP (30%–60% were determined before and after thermal cycling between 5°C and 55°C in deionized water for 600 cycles. The trends of all groups were ductile prior to thermal cycling and the moduli of all groups increased after thermal cycling. The ductile property of the control group without filler was not significantly affected. Larger amounts of fillers caused the particles to aggregate, subsequently decreasing the resin’s ability to disperse external forces and leading to brittleness after thermal cycling. Therefore, the trend of composite resins with larger amounts of filler would become more brittle and exhibited higher moduli after thermal cycling. This developed composite resin with surface modified-TTCP fillers has the potential to be successful dental restorative materials.

  8. Temperature rise during adhesive and composite polymerization with different light-curing sources.

    Science.gov (United States)

    Pereira Da Silva, A; Alves Da Cunha, L; Pagani, C; De Mello Rode, S

    2010-05-01

    This study evaluated the temperature rise of the adhesive system Single Bond (SB) and the composite resins Filtek Z350 flow (Z) and Filtek Supreme (S), when polymerized by light-emitting diode (LED XL 3000) and quartz-tungsten halogen (QTH Biolux). Class V cavities (3 yen2 mm) were prepared in 80 bovine incisors under standardized conditions. The patients were divided as follows: G1: Control; G2: SB; G3: SB + Z; G4: SB + S. The groups were subdivided into two groups for polymerization (A: QTH, B: LED). Light curing was performed for 40 s and measurement of temperature changes during polymerization was performed with a thermocouple positioned inside the pulp chamber. Data were statistically analyzed using ANOVA and Tukey tests. The factors material (P<0.00001) and curing unit (P<0.00001) had significant influence on temperature rise. The lowest temperature increase (0.15 degrees C) was recorded in G2 B and the highest was induced in G1 A (0.75 degrees C, P<0.05). In all groups, lower pulp chamber temperature measurements were obtained when using LED compared to QTH (P<0.05). QTH caused greater increases in tooth temperature than LED. However, both sources did not increase pulpal temperature above the critical value that may cause pulpal damage.

  9. Anhydrides-Cured Bimodal Rubber-Like Epoxy Asphalt Composites: From Thermosetting to Quasi-Thermosetting

    Directory of Open Access Journals (Sweden)

    Yang Kang

    2016-03-01

    Full Text Available The present engineering practices show the potential that epoxy asphalt composites (EACs would be a better choice to obtain long life for busy roads. To understand the service performance–related thermorheological properties of prepared bimodal anhydrides-cured rubber-like EACs (REACs, a direct tensile tester, dynamic shear rheometer and mathematical model were used. Tensile tests demonstrate that all the REACs reported here are more flexible than previously reported anhydrides-cured REACs at both 20 and 0 °C. The better flexibility is attributed to the change of bimodal networks, in which cross-linked short chains decreased and cross-linked long chains increased, relatively. Strain sweeps show that all the REACs have linear viscoelastic (LVE properties when their strains are smaller than 1.0% from −35 to 120 °C. Temperature sweeps illustrate that the thermorheological properties of REACs evolve from thermosetting to quasi-thermosetting with asphalt content, and all the REACs retain solid state and show elastic properties in the experimental temperature range. A Cole–Cole plot and Black diagram indicate that all the REACs are thermorheologically simple materials, and the master curves were constructed and well-fitted by the Generalized Logistic Sigmoidal models. This research provides a facile approach to tune the thermorheological properties of the REACs, and the cheaper quasi-thermosetting REAC facilitates their advanced applications.

  10. Thio-urethanes improve properties of dual-cured composite cements.

    Science.gov (United States)

    Bacchi, A; Dobson, A; Ferracane, J L; Consani, R; Pfeifer, C S

    2014-12-01

    This study aims at modifying dual-cure composite cements by adding thio-urethane oligomers to improve mechanical properties, especially fracture toughness, and reduce polymerization stress. Thiol-functionalized oligomers were synthesized by combining 1,3-bis(1-isocyanato-1-methylethyl)benzene with trimethylol-tris-3-mercaptopropionate, at 1:2 isocyanate:thiol. Oligomer was added at 0, 10 or 20 wt% to BisGMA-UDMA-TEGDMA (5:3:2, with 25 wt% silanated inorganic fillers) or to one commercial composite cement (Relyx Ultimate, 3M Espe). Near-IR was used to measure methacrylate conversion after photoactivation (700 mW/cm(2) × 60s) and after 72 h. Flexural strength and modulus, toughness, and fracture toughness were evaluated in three-point bending. Polymerization stress was measured with the Bioman. The microtensile bond strength of an indirect composite and a glass ceramic to dentin was also evaluated. Results were analyzed with analysis of variance and Tukey's test (α = 0.05). For BisGMA-UDMA-TEGDMA cements, conversion values were not affected by the addition of thio-urethanes. Flexural strength/modulus increased significantly for both oligomer concentrations, with a 3-fold increase in toughness at 20 wt%. Fracture toughness increased over 2-fold for the thio-urethane modified groups. Contraction stress was reduced by 40% to 50% with the addition of thio-urethanes. The addition of thio-urethane to the commercial cement led to similar flexural strength, toughness, and conversion at 72h compared to the control. Flexural modulus decreased for the 20 wt% group, due to the dilution of the overall filler volume, which also led to decreased stress. However, fracture toughness increased by up to 50%. The microtensile bond strength increased for the experimental composite cement with 20 wt% thio-urethane bonding for both an indirect composite and a glass ceramic. Novel dual-cured composite cements containing thio-urethanes showed increased toughness, fracture toughness and

  11. Coating composition curable by electron beam irradiation

    International Nuclear Information System (INIS)

    Masuda, Hiromasa; Iijima, Ken-ichi.

    1971-01-01

    Here is provided a coating composition curable with low dose of electron beams to give a smooth coating film having no surface tackiness. In one example, 126 parts of melamine was reacted with 682 parts of formalin followed by 697 parts of β-hydroxyethyl acrylate to produce component (A) (viscosity 780 cp). On the other hand, 900 parts of tung oil was reacted with 343 parts of maleic anhydride followed by 22 parts of dimethylaminoethyl methacrylate and 406 parts of β-hydroxyethyl acrylate. The resulting product was diluted with 508 parts of methyl methacrylate to give component (B) (dark red, viscous substance). 900 parts of (A), 100 parts of (B), 0.5 part of bees wax and 0.2 part of paraffin wax were blended together. A sized material was coated with the mixture and irradiated with electron beams (6 Mrad) in the presence of air. A smooth film free from surface tackiness was obtained. β-hydroxyethyl acrylate may be replaced by other hydroxyalkyl esters of α,β-unsaturated acids, and melamine may be replaced by urea, benzoguanamine or acetoguanamine. Tung oil may be replaced by linseed, safflower, soybean, rice, oiticica or cotton seed oil. A more flexible film is obtained by using component (B) in a larger proportion. (A)/(B) ratio should be in the range of 90/10 to 10/90 by wt. (Kaichi, S.)

  12. Optimal temperature profiles for minimum residual stress in the cure process of polymer composites

    CSIR Research Space (South Africa)

    Gopal, AK

    2000-01-01

    Full Text Available include the minimum residual stresses, minimum cure cycle lime and full degree of cure. The development of residual stresses during the cure cycle is one of the most important problems as they affect the strength and the mechanical properties of the final...

  13. Radiation Curing of Rubber/Thermoplastic Composites Containing Different Inorganic Fillers

    International Nuclear Information System (INIS)

    EL-Zayat, M.M.M.

    2012-01-01

    Blending of polymeric materials has proved to be a successful method for preparing new polymeric materials having not only the main properties of the blends components but also new modification as well as specific ones. High density polyethylene (HDPE) and acrylonitrile butadiene rubber (NBR) are both soild and constitute the blend components to be investigated in present study and hence the method of mechanical blending is the most suitable one for its preparation . HDPE thermoplastic is a semi – crystalline polymer ; on the other hand , NBR elastomer is totally amorphous polymer. Both polymers are categorized as crosslinking polymers with respect to ionizing gamma rays with different extents. In order to increase the efficiency of irradiation curing of such NBR/HDPE blend , it may be required to add suitable additives such as reinforcing fillers that may increase the extent of crosslinking at the same irradiation dose . Thus synthetic fillers are used commercially in industrial processing of rubber formulation due to its specific characteristics and hence its high reinforcing capacity and suitable price . To follow property changes occurred to the blend as well as its composites , measurements have been done to monitor the changes that happened to mechanical, physical and thermal properties as a function of irradiation dose and composition of blends and composites.

  14. Shrinkage Characteristics of Experimental Polymer Containing Composites under Controlled Light Curing Modes

    Directory of Open Access Journals (Sweden)

    Alain Pefferkorn

    2012-01-01

    Full Text Available The adsorption of polymethylmethacrylate polymer of different molecular weight at the aerosil/ethyleneglycol- or 1,3 butanediol-dimethacrylate interfaces was determined to provide microstructured networks. Their structural characteristics were determined to be controlled by the amount of polymer initially supplied to the system. The sediment (the settled phase characteristics, determined as a function of the polymer concentration and the rate of the polymerization shrinkage determined for composite resins, obtained by extrusion of the sediment after centrifugation, were found to be correlated. The specific role of the adsorbed polymer was found to be differently perturbed with the supplementary supply of dimethacrylate based monomer additives. Particularly, the bisphenol A dimethacrylate that generated crystals within the sediment was found to impede the shrinkage along the crystal lateral faces and strongly limit the shrinkage along its basal faces. Addition of ethyleneglycol- or polyethylene-glycoldimethacrylate monomers was determined to modify the sedimentation characteristics of the aerosil suspension and the shrinkage properties of the composites. Finally, the effects of stepwise light curing methods with prolonged lighting-off periods were investigated and found to modify the development and the final values of the composite shrinkage.

  15. Rubber-like Quasi-thermosetting Polyetheramine-cured Epoxy Asphalt Composites Capable of Being Opened to Traffic Immediately.

    Science.gov (United States)

    Kang, Yang; Wu, Qiang; Jin, Rui; Yu, Pengfei; Cheng, Jixiang

    2016-01-06

    This paper reports the facile preparation, mechanical performance and linear viscoelasticity of polyetheramine-cured rubber-like epoxy asphalt composites (EACs) with different asphalt contents. Compared with previous EACs prepared via complex chemical reactions and time-consuming high-temperature curing, the EACs reported here were obtained by using a compatible, bi-functional polyetheramine and a simple physical co-blend process, which make the EACs feasibly scalable for production at a lower cost. The EACs were cured for 1 h at 160 °C and 3 d at 60 °C; therefore, these composites can be opened to traffic immediately. The EACs have a much greater temperature stability than common thermoplastic polymer-modified asphalt composites from -30 °C to 120 °C, but their complex shear moduli at higher temperatures slightly decrease instead of remaining constant when temperatures are greater than 80 °C, especially for the higher asphalt content composites; that is, these composites are quasi-thermosetting. Wicket plots illustrate that the EACs reported here are thermorheological simple materials, and the master curves are constructed and well-fitted by generalized logistic sigmoidal model functions. This research provides a facile, low-cost method for the preparation of polyetheramine-cured EACs that can be opened to traffic immediately, and the concept of quasi-thermosetting may facilitate the development of cheaper EACs for advanced applications.

  16. Rubber-like Quasi-thermosetting Polyetheramine-cured Epoxy Asphalt Composites Capable of Being Opened to Traffic Immediately

    Science.gov (United States)

    Kang, Yang; Wu, Qiang; Jin, Rui; Yu, Pengfei; Cheng, Jixiang

    2016-01-01

    This paper reports the facile preparation, mechanical performance and linear viscoelasticity of polyetheramine-cured rubber-like epoxy asphalt composites (EACs) with different asphalt contents. Compared with previous EACs prepared via complex chemical reactions and time-consuming high-temperature curing, the EACs reported here were obtained by using a compatible, bi-functional polyetheramine and a simple physical co-blend process, which make the EACs feasibly scalable for production at a lower cost. The EACs were cured for 1 h at 160 °C and 3 d at 60 °C therefore, these composites can be opened to traffic immediately. The EACs have a much greater temperature stability than common thermoplastic polymer-modified asphalt composites from -30 °C to 120 °C, but their complex shear moduli at higher temperatures slightly decrease instead of remaining constant when temperatures are greater than 80 °C, especially for the higher asphalt content composites; that is, these composites are quasi-thermosetting. Wicket plots illustrate that the EACs reported here are thermorheological simple materials, and the master curves are constructed and well-fitted by generalized logistic sigmoidal model functions. This research provides a facile, low-cost method for the preparation of polyetheramine-cured EACs that can be opened to traffic immediately, and the concept of quasi-thermosetting may facilitate the development of cheaper EACs for advanced applications.

  17. Raman spectroscopic assessment of degree of conversion of bulk-fill resin composites--changes at 24 hours post cure.

    Science.gov (United States)

    Par, M; Gamulin, O; Marovic, D; Klaric, E; Tarle, Z

    2015-01-01

    The aim of this study was to determine degree of conversion (DC) of solid and flowable bulk-fill composites immediately and after 24 hours and investigate the variations of DC at surface and depths up to 4 mm. Eight bulk-fill composites (Tetric EvoCeram Bulk Fill [shades IVA and IVB], Quixfil, X-tra fil, Venus Bulk Fill, X-tra Base, SDR, Filtek Bulk Fill) were investigated, and two conventional composites (GrandioSO, X-Flow) were used as controls. The samples (n = 5) were cured for 20 seconds with irradiance of 1090 mW/cm(2). Raman spectroscopic measurements were made immediately after curing on sample surfaces and after 24 hours of dark storage at surface and at incremental depths up to 4 mm. Mean DC values were compared using repeated measures analysis of variance (ANOVA) and t-test for dependent samples. Surface DC values immediately after curing ranged from 59.1%-71.8%, while the 24-hour postcure values ranged from 71.3%-86.1%. A significant increase of DC was observed 24 hours post cure for all bulk-fill composites, which amounted from 11.3% to 16.9%. Decrease of DC through depths up to 4 mm varied widely among bulk-fill composites and ranged from 2.9% to 19.7%. All bulk-fill composites presented a considerable 24-hour postcure DC increase and clinically acceptable DC at depths up to 4 mm. Conventional control composites were sufficiently cured only up to 2 mm, despite significant postcure polymerization.

  18. A Simplified Analysis of the Brazier Effect in Composite Beams

    DEFF Research Database (Denmark)

    Damkilde, Lars; Lund, B.

    2009-01-01

    In the design of windturbine blades composite beams are often used as the load bearing element. The beam is primarily subjected to bending moments, and the deformations are relatively large. The large displacements result in a kind of ovalization of the beam section, the so-called Brazier effect...

  19. Country Report Malaysia [Radiation Curing of Composites for Enhancing the Features and Utility in Health Care and Industry

    International Nuclear Information System (INIS)

    Nik Ghazali Nik Salleh

    2011-01-01

    Polymerization active silico-organic nanoparticles could be prepared by heterogeneous condensation reaction and formed crosslinks in the polymeric substrates. With a relatively high nanopowder content of the nanodispersions, these coating materials could still be cured by ultraviolet light and produced excellent polymeric composites. These coating materials show better resistances toward scratch and abrasion properties compared to pure acrylates. (author)

  20. Country Report Malaysia [Radiation Curing of Composites for Enhancing the Features and Utility in Health Care and Industry

    Energy Technology Data Exchange (ETDEWEB)

    Nik Ghazali Nik Salleh, E-mail: Nik_Ghazali@nuclearmalaysia.gov.my [Malaysian Nuclear Agency, Block 42, Bangi, 43000 Kajang, Selangor (Malaysia)

    2011-07-01

    Polymerization active silico-organic nanoparticles could be prepared by heterogeneous condensation reaction and formed crosslinks in the polymeric substrates. With a relatively high nanopowder content of the nanodispersions, these coating materials could still be cured by ultraviolet light and produced excellent polymeric composites. These coating materials show better resistances toward scratch and abrasion properties compared to pure acrylates. (author)

  1. Polymer-layered silicate nano composite by UV-radiation curing: an original synthesis

    International Nuclear Information System (INIS)

    Keller, L.; Decker, C.; Zahouily, K.; Miehe-Brendle, J.; Le Meins, J.M.

    2004-01-01

    Full text.Because of the many hopes which they raise, the nano composite materials are the subject of an increasing number of scientific publications. Indeed, the intimate association of a polymer matrix and silicate nano-platelets leads to the formation of materials having mechanical and barriers properties improved (fire, gas, humidity...). A literature survey shows that these materials are generally produced by a thermal polymerization, which presents two major disadvantages: the use of organic solvents and a great consumption of energy. To overcome such limitations, photo initiated polymerization was chosen to synthesize nano composite materials. By this technology, called UV radiation curing, a solvent-free resin is transformed within seconds into a solid polymer upon exposure to UV-radiation at ambient temperature. The principal objective of this study was to develop photopolymerizable systems with clay particles having a layer structure (phyllosilicates). The clay mineral was made organophilic by treatment with an alkylammonium salt to allow the acrylate resin to penetrate into the expanded galleries. A morphological characterization of the materials obtained was carried out by X-rays diffraction and electronic microscopy transmission. The polymerization of the various resins under the UV exposure was followed in situ by using the real-time infrared spectroscopy (RT-FTIR) and attenuated total reflection (ATR). The results obtained show that the presence of the organo clay does not modify much the polymerization kinetics. The nano composite material thus obtained is transparent, insoluble in the organic solvents and presents improved mechanical properties, compared to the neat resin and the micro composite, for a load factor ranging between 2 and 5%wt. The addition of nanoparticles also makes it possible to reduce efficiently the brightness of coatings UV and finally confers to this material barriers properties higher than that of the photo crosslinked

  2. Bacteriological cure rate and changes in milk composition in mastitis vaccinated ewes affected with subclinical mastitis.

    Science.gov (United States)

    Alekish, Myassar O; Ismail, Z Bani; Hammouri, H M; Daradka, M H; Taha, S Al; Olymat, I

    2018-02-01

    The aim of this study was to investigate the effects of using a commercially-available polyvalent mastitis vaccine on the bacteriological cure rate of existing subclinical mastitis in Awassi sheep. A total of 164 lactating ewes were divided into two main groups according to udder health and milk somatic cell count (SCC): Group 1=normal (N; n=80) and Group 2=subclinical mastitis (SC; n=84). Each group was then subdivided randomly into two treatment groups: N vaccinated (N vax ; n=38), N non-vaccinated (N nvax ; n=42), SC vaccinated (SC vax ; n=42), and SC non-vaccinated (SC nvax ; n=42). The vaccine was administered as per manufacturer's recommendations. Milk samples were collected aseptically from all ewes before vaccine administration (T0) and again on days 28 (T2) and 42 (T3) of the experiment. In the SC group, the bacteriological cure rates in vaccinated and non-vaccinated ewes were 76% and 69%, respectively. In N group, the new intramammary infection rates in vaccinated and non-vaccinated ewes were 48% and 50%, respectively. Vaccination of normal ewes resulted in a significant (pewes on days 28 and 42 was 19% and 20%, respectively. The prevalence of new intramammary infection rate in N nvax group on days 28 and 42 was 33% and 30%, respectively. In SC vax group, the bacterial growth rate on days 28 and 42 was 44% and 35%, respectively. In SC nvax group, the bacterial growth rate on days 28 and 42 was 27% and 32%, respectively. There was no statistically significant effect of vaccination on any of the studied milk composition parameters. This is a preliminary study that indicated a possible protective effect of vaccination against mastitis in sheep. Further, case-controlled studies are indicated to estimate the level of immunity this vaccine provides to vaccinated sheep.

  3. Structure-to-property relationships in addition cured polymers. II - Resin Tg and composite initial mechanical properties of norbornenyl cured polyimide resins

    Science.gov (United States)

    Alston, William B.

    1986-01-01

    PRM (polymerization of monomeric reactants) methodology was used to prepare thirty different polyimide oligomeric resins. Monomeric composition as well as chain length between sites of crosslinks were varied to examine their effects on glass transition temperature (Tg) of the cured/postcured resins. An almost linear correlation of Tg versus molecular distance between the crosslinks was observed. An attempt was made to correlate Tg with initial mechanical properties (flexural strength and interlaminar shear strength) of unidirectional graphite fiber composites prepared with these resins. However, the scatter in mechanical strength data prevented obtaining as clear a correlation as was observed for the structural modification/crosslink distance versus Tg. Instead, only a range of composite mechanical properties was obtained at the test temperatures studied (room temperature, 288 and 316 C). Perhaps more importantly, what did become apparent during the attempted correlation study was: (1) that PMR methodology could be used to prepare composites from resins that contain a wide variety of monomer modifications, and (2) that these composites almost invariably provided satisfactory initial mechanical properties as long as the resins selected were melt processable.

  4. The Influence of Water Sorption of Dental Light-Cured Composites on Shrinkage Stress

    Directory of Open Access Journals (Sweden)

    Kinga Bociong

    2017-09-01

    Full Text Available The contraction stress generated during the photopolymerization of resin dental composites is the major disadvantage. The water sorption in the oral environment should counteract the contraction stress. The purpose was to evaluate the influence of the water sorption of composite materials on polymerization shrinkage stress generated at the restoration-tooth interface. The following materials were tested: Filtek Ultimate, Gradia Direct LoFlo, Heliomolar Flow, Tetric EvoCeram, Tetric EvoCeram Bulk Fill, Tetric EvoFlow, Tetric EvoFlow Bulk Fill, X-tra Base, Venus BulkFil, and Ceram.X One. The shrinkage stress was measured immediately after curing and after: 0.5 h, 24 h, 72 h, 96 h, 168 h, 240 h, 336 h, 504 h, 672 h, and 1344 h by means of photoelastic study. Moreover, water sorption and solubility were evaluated. Material samples were weighted on scale in time intervals to measure the water absorbency and the dynamic of this process. The tested materials during polymerization generated shrinkage stresses ranging from 6.3 MPa to 12.5 MPa. Upon water conditioning (56 days, the decrease in shrinkage strain (not less than 48% was observed. The decrease in value stress in time is material-dependent.

  5. Effect of different photo-initiators and light curing units on degree of conversion of composites.

    Science.gov (United States)

    Brandt, William Cunha; Schneider, Luis Felipe Jochims; Frollini, Elisabete; Correr-Sobrinho, Lourenço; Sinhoreti, Mário Alexandre Coelho

    2010-01-01

    The aim of this study was to evaluate: (i) the absorption of photo-initiators and emission spectra of light curing units (LCUs); and (ii) the degree of conversion (DC) of experimental composites formulated with different photo-initiators when activated by different LCUs. Blends of BisGMA, UDMA, BisEMA and TEGDMA with camphorquinone (CQ) and/ or 1-phenyl-1,2-propanedione (PPD) were prepared. Dimethylaminoethyl methacrylate (DMAEMA) was used as co-initiator. Each mixture was loaded with 65 wt% of silanated filler particles. One quartz-tungsten-halogen - QTH (XL 2500, 3M/ESPE) and two lightemitting diode (LED) LCUs (UltraBlue IS, DMC and UltraLume LED 5, Ultradent) were used for activation procedures. Irradiance (mW/cm²) was calculated by the ratio of the output power by the area of the tip, and spectral distribution with a spectrometer (USB 2000). The absorption curve of each photo-initiator was determined using a spectrophotometer (Varian Cary 5G). DC was assessed by Fourier transformed infrared spectroscopy. Data were submitted to two-way ANOVA and Tukey's test (5%). No significant difference was found for DC values when using LED LCUs regardless of the photo-initiator type. However, PPD showed significantly lower DC values than composites with CQ when irradiated with QTH. PPD produced DC values similar to those of CQ, but it was dependent on the LCU type.

  6. Analysis of gap formation at tooth-composite resin interface: effect of C-factor and light-curing protocol

    Directory of Open Access Journals (Sweden)

    Gustavo Oliveira dos Santos

    2007-08-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the effect of C-factor and light-curing protocol on gap formation in composite resin restorations. Material and METHODS: Cylindrical cavities with 5.0 mm diameter and three different depths (A=1.0, B=2.0 and C=3.0 mm were prepared on the occlusal surface of 30 human molars and restored in a single increment with P 60. The composite resin was light-cured according to two protocols: standard - 850 mW/cm² / 20 s and gradual - 100 up to 1000 mW/cm² / 10 s + 1000 mW/cm² / 10 s. After storage in distilled water (37°C/7 days, the restorations were cut into three slices in a buccolingual direction and the gap widths were analyzed using a 3D-scanning system. The data were submitted to ANOVA and Student-Newman-Keuls test (alpha=0.05. RESULTS: ANOVA detected a significant influence for the C-factor and light-curing protocol as independent factors, and for the double interaction C-factor vs. light-curing protocol. Cavities with higher C-factor presented the highest gap formation. The gradual light-curing protocol led to smaller gap formation at cavity interfaces. CONCLUSIONS: The findings of this study suggest that the C-factor played an essential role in gap formation. The gradual light-curing protocol may allow relaxation of composite resin restoration during polymerization reaction.

  7. Effect of Particular Breed on the Chemical Composition, Texture, Color, and Sensorial Characteristics of Dry-cured Ham

    OpenAIRE

    Seong, Pil Nam; Park, Kuyng Mi; Kang, Sun Moon; Kang, Geun Ho; Cho, Soo Hyun; Park, Beom Young; Van Ba, Hoa

    2014-01-01

    The present study demonstrates the impact of specific breed on the characteristics of dry-cured ham. Eighty thighs from Korean native pig (KNP), crossbreed (Landrace×Yorkshire)♀×Duroc♂ (LYD), Berkshire (Ber), and Duroc (Du) pig breeds (n = 10 for each breed) were used for processing of dry-cured ham. The thighs were salted with 6% NaCl (w/w) and 100 ppm NaNO2, and total processing time was 413 days. The effects of breed on the physicochemical composition, texture, color and sensory characteri...

  8. Thermoplastic impact property improvement in hybrid natural fibre epoxy composite bumper beam

    International Nuclear Information System (INIS)

    Davoodi, M M; Sapuan, S M; Ali, Aidy; Ahmad, D; Khalina, A

    2010-01-01

    Utilization of thermoset resin as a bumper beam composite matrix is currently more dominated in car manufacturer suppliers, because of availability, easy processing, low material cost and production equipment investment. Moreover, low viscosity, shrinkage and excellent flow facilitate better fibre impregnation and proper surface resin wetting. Three-dimensional cross linking curing increase impact, creep and environmental stress cracking resistance properties. Low impact properties of natural fibre epoxy composite, are main issues in its employment for automotive structural components. Impact properties in epoxy composite bumper beam could be increased by modifying the resin, reinforcement and manufacturing process as well as geometry parameters such as cross section, thickness, added ribs and fixing method optimizations could strengthen impact resistance. There are two main methods, flexibilisation and toughening, as modifying the resin in order to improve the impact properties of epoxy composite, which form single phase or two-phase morphology to make modifier as epoxy or from separate phase to keep the thermo-mechanical properties. Liquid rubber, thermoplastic, core shell particle and rigid particle are different methods of toughening improvements. In this research, thermoplastic toughening has used to improve impact properties in hybrid natural fibre epoxy composite for automotive bumper beam and has achieved reasonable impact improvements.

  9. How carbon nanotubes affect the cure kinetics and glass transition temperature of their epoxy composites? – A review

    Directory of Open Access Journals (Sweden)

    2009-09-01

    Full Text Available Motivated by the widespread and contradictory results regarding the glass transition temperature of carbon nanotube (CNT/epoxy composites, we reviewed and analyzed the literature results dealing with the effect of unmodified multiwall carbon nanotubes (MWNT on the cure behaviour of an epoxy resin (as a possible source of this discrepancy. The aim of this work was to clarify the effective role of unmodified multiwall carbon nanotubes on the cure kinetics and glass transition temperature (Tg of their epoxy composites. It was found that various authors reported an acceleration effect of CNT. The cure reaction was promoted in its early stage which may be due to the catalyst particles present in the CNT raw material. While SWNT may lead to a decrease of Tg due to their bundling tendency, results reported for MWNT suggested an increased or unchanged Tg of the composites. The present status of the literature does not allow to isolate the effect of MWNT on the Tg due to the lack of a study providing essential information such as CNT purity, glass transition temperature along with the corresponding cure degree.

  10. Synthesis of non-ionic and ionic resins for BEP intaglio inks curing by electron-beam radiation. Annual report

    International Nuclear Information System (INIS)

    Bauer, B.J.; Dickens, B.

    1992-01-01

    The inks currently used to print US postage stamps on web presses are dried by heat evaporation of solvents. Emission of solvents into the atmosphere is governed by Local and Federal Government Regulations. Reduction of these emissions to acceptable levels can be accomplished by either of two methods available to the BEP. The work was part of a continuing effort to produce resins for use in formulation of intaglio inks for the printing of postage stamps and security documents. The inks are to be cured by exposure to an electron beam. The uncured inks are cleaned from the roller and wiping blade by washing the wiping blade with neutral water or with caustic water. Laboratory scale work on the urethane/polyethylene oxide/methacrylate resins has now been concluded and information on the synthesis has been provided to BEP for patenting and scaleup. Some effort on nonionic resins continued into FY88

  11. Factors influencing photo curing kinetics of novel UV-cured siloxane-modified acrylic coatings: Oxygen inhibition and composition

    International Nuclear Information System (INIS)

    Esposito Corcione, Carola; Frigione, Mariaenrica

    2012-01-01

    Highlights: ► The inhibition effect of oxygen on the kinetic behaviour of photopolymerizable siloxane acrylic formulations was analyzed by thermal analysis. ► The addition of a thiol in the mixtures allows to obtain higher conversion, to reduce the content of the UV initiator and to increase the T g . ► The data found in air were fitted as a function of the presence of the thiol monomer obtaining a good agreement. - Abstract: An experimental study was carried out for the development and characterization of innovative photopolymerizable siloxane-modified acrylic formulations for possible use as protective coatings of stone substrates. The kinetics of the radical photopolymerization mechanism induced by UV radiations in presence of a suitable photoinitiator was studied by a calorimetric analysis by varying the atmosphere (oxygen or nitrogen) and the composition of the mixtures, in particular of the UV photoinitiator. The reactivity, expressed in terms of both heat developed and rate of reaction, was generally found to decrease when the photopolymerization was carried out in air, due the inhibiting action of the oxygen towards the free radical polymerization. The addition of a proper thiol to the acrylic modified resin was found to reduce the adverse effect of oxygen on the kinetic reaction and on the degree of conversion. This result allowed to reduce the content of the photoinitiator and to increase the content of the siloxane in the acrylic based mixtures. The effect of the change of the composition of the formulations on the kinetic behaviour of the acrylic based resins was also analysed by calorimetric analysis. Calorimetric experimental data were fitted to a simple kinetic model for radical photopolymerization reactions. Finally, a proper relationship between the glass transition temperature and the total extent of reaction was applied to the experimental data. A good agreement between the experimental data and both the theoretical models was generally

  12. Investigation of a carbon fiber/epoxy prepreg curing behavior for thick composite materials production: An industrial case-study

    Science.gov (United States)

    Giorgini, Loris; Mazzocchetti, Laura; Minak, Giangiacomo; Dolcini, Enrico

    2012-07-01

    A case-study is presented, in cooperation with RI-BA Composites srl, where the industrial production of a thick part for primary structural application is analysed. The final product is a bulk carbon fiber reinforced object characterized by great dimensions, with thickness ranging between 10mm and 35mm and obtained by Hand-Lay-Up of prepregs. The study shows that prepregs age along the time required for the process work up. Moreover, the isothermal curing investigation of the prepreg used in the production gives some useful hint for the design of a new thermal curing cycle, in order to avoid exotherm problems along the thickness of the object. The effect of the applied curing cycle on thermal properties of the object are reported.

  13. Influence of curing profile and fibre architecture on the fatigue resistance of composite materials for wind turbine blades

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard

    been investigated during a variety of curing profiles of the used epoxy material system. Thereby, it is possible to observe that even though the overall chemical shrinkage of the epoxy material system is independent on the chosen curing profile, the location of the gel-point and thereby the amount......The fatigue performance of unidirectional glass fibre reinforced epoxy is found to be highly dependent on the manufacturing conditions, where a low manufacturing temperature, for the investigated wind turbine relevant composite material system, is found to improve the tension/tension fatigue life....... It is a failure mechanism which is judge to be highly influenced by the magnitude of the residual stresses exhibit in the matrix material and therefore also in the secondary oriented backing bundles. Using fibre Bragg grated optical fibres2; the build-up of the cure-induced strains in the fibre-reinforcement has...

  14. Influence of different curing methods on the fatty acid composition in sausages prepared from red deer meat

    Directory of Open Access Journals (Sweden)

    Marek Šnirc

    2016-11-01

    Full Text Available These curing agents play a decisive role in obtaining the specific sensory properties, stability and hygienic safety of products such as fermented sausages, ham and, more recently, emulsion type of sausages. The effect of using two different curing agents (sodium chloride and nitrate on fatty acid compounds in dry-cured deer meat was investigated in our study. The concentration of free fatty acids in the fat depends on the hydrolytic activity of the lipases, the microbial metabolic processes, and the oxidative reactions that work on the free fatty acids released in the lipolysis. The main identified fatty acids in all different types of curing were palmitic acid (16 : 0, oleic acid (c18 : 1 cis-9, stearic acid (C18 : 0. The resulting n-6/n-3 PUFA ratio in the muscle samples of red deer showed no variation in different types of curing and was beneficially low within the range of 3.9 : 1 and 4.49 : 1. Total free fatty acids, whether saturated, monounsaturated or polyunsaturated fatty acids, did not increased (p >0.05 greatly through the processing of dry-cured deer meat. Also there was no effect of curing method on fatty acids composition in two different muscles Semitendinosus muscle (ANOVA, p >0.05, F - 0.003, F crit. - 3.041 and Triceps brachii muscle (ANOVA, p >0.05, F - 0.05, F crit. - 3.01. There were found no significant (p >0.05 differences between fatty acids content in sausages prepared by brining in NaCl and Nitrate salt. The present study revealed that game meat can function as a good source of bioactive compounds that are essential for human nutrition. 

  15. Compressive strength measurements of hybrid dental composites treated with dry heat and light emitting diodes (LED post cure treatment

    Directory of Open Access Journals (Sweden)

    Jenny Krisnawaty

    2014-11-01

    Full Text Available Hybrid composites are mostly used on large cavities as restorative dental materials, whether it is used directly or indirectly. The mechanical properties of composite resin shall increase if it is treated with post cure treatment. The aim of this study is to evaluate compressive strength differences between dry heat and Light Emitting Diodes (LED treatment on the hybrid dental composite. A quasi-experimental was applied on this research with a total of 30 samples that were divided into two groups. Each sample was tested using LLOYD Universal Testing Machine with 1 mm/min speed to evaluate the compressive strength. The compressive strength results were marked when the sample was broken. The results of two groups were then analyzed using t-test statistical calculation. The results of this study show that post cure treatment on hybrid composite using LED light box (194.138 MPa was lower than dry heat treatment (227.339 MPa, which was also significantly different from statistical analysis. It can be concluded that compressive strength of LED light box was lower than dry heat post-cure treatment on the hybrid composite resin.

  16. Simulation of Air Entrapment and Resin Curing During Manufacturing of Composite Cab Front by Resin Transfer Moulding Process

    Directory of Open Access Journals (Sweden)

    Kuppusamy Raghu Raja Pandiyan

    2017-09-01

    Full Text Available Mould filling and subsequent curing are the significant processing stages involved in the production of a composite component through Resin Transfer Moulding (RTM fabrication technique. Dry spot formation and air entrapment during filling stage caused by improper design of filling conditions and locations that lead to undesired filling patterns resulting in defective RTM parts. Proper placement of inlet ports and exit vents as well as by adjustment of filling conditions can alleviate the problems during the mould filling stage. The temperature profile used to polymerize the resin must be carefully chosen to reduce the cure time. Instead of trial and error methods that are expensive, time consuming, and non-optimal, we propose a simulation-based optimization strategy for a composite cab front component to reduce the air entrapment and cure stage optimization. In order to be effective, the optimization strategy requires an accurate simulation of the process utilizing submodels to describe the raw material characteristics. Cure reaction kinetics and chemo-rheology were the submodels developed empirically for an unsaturated polyester resin using experimental data. The simulations were performed using commercial software PAM RTM 2008, developed by ESI Technologies. Simulation results show that the use of increase in injection pressure at the inlet filling conditions greatly reduce the air entrapped. For the cab front, the alteration of injection pressure with proper timing of vent opening reduced the air entrapped during mould filling stage. Similarly, the curing simulation results show that the use of higher mould temperatures effectively decreases the cure time as expected.

  17. Effects of various light curing methods on the leachability of uncured substances and hardness of a composite resin.

    Science.gov (United States)

    Moon, H-J; Lee, Y-K; Lim, B-S; Kim, C-W

    2004-03-01

    The purpose of this study was to evaluate the effect of the various light curing units (plasma arc, halogen and light-emitting diodes) and irradiation methods (one-step, two-step and pulse) using different light energy densities on the leachability of unreacted monomers (Bis-GMA and UDMA) and the surface hardness of a composite resin (Z250, 3M). Leachability of the specimens immersed for 7 days in ethanol was analysed by HPLC. Vicker's hardness number (VHN) was measured immediately after curing (IC) and after immersion in ethanol for 7 days. Various irradiation methods with three curing units resulted in differences in the amount of leached monomers and VHN of IC when light energy density was lower than 17.0 J cm(-2) (P = 0.05). However, regardless of curing units and irradiation methods, these results were not different when the time or light energy density increased. When similar light energy density was irradiated (15.6-17.7 J cm(-2)), the efficiency of irradiation methods was different by the following order: one-step > or = two-step > pulse. These results suggest that the amount of leached monomers and VHN were influenced by forming polymer structure in activation and initiation stages of polymerization process with different light source energies and curing times.

  18. Radiation curing - a personal perspective

    International Nuclear Information System (INIS)

    Pappas, S.P.

    1992-01-01

    This chapter briefly introduces radiation curing from the personal perspective of the author. Topics covered in this chapter include characteristic features of radiation curing, photoinitiated polymerization -- ultraviolet (UV) curing, and general principles of electron beam (EB) curing. 57 refs., 2 tabs

  19. The effect of curing units and methods on degree of conversion of two types of composite resins

    Directory of Open Access Journals (Sweden)

    Hasani Tabatabaei M

    2007-06-01

    Full Text Available Background and Aim: Halogen lamp is the commonly used light source for composite photo polymerization. Recently, high power halogen lamps, LED and plasma arc are introduced for improving the polymerization. The aim of this study was to investigate the effect of conventional and high power halogen lamps and LED light curing unit on degree of conversion of two different composite resins.Materials and Methods: In this in vitro experimental study two halogen units (Coltolux 50 with the intensity of  330 mW/cm2 and Optilux 501 with two different operating modes of standard with the intensity of 820 mW/cm2 and Ramp with the intentsiy of 100-1030mW/cm2 and one LED light curing unit (620 mW/cm2 were used. The composites were hybrid (Tetric ceram and nanofilled (Filteke supreme. Each materials/curing method contained three samples and degree of conversion (DC was measured with FTIR. Data were analyzed statistically with one way and two way ANOVA, Tukey HSD. P<0.05 was considered as the limit of significance.Results: Tetric ceram revealed higher DCthan Supreme. Tetric ceram showed a significant decrease in DC when Coltolux 50 was used in comparison to LED and Optilux 501. The latters did not show significant effect on DC of this material. DC of Supreme polymerized with various curing modes was not significantly different.Conclusion: Based on the results of this study, degree of conversion in hybrid composites was higher than nanofilled. In comparison with conventional halogen lamp (Coltolux 50, high intensity halogen lamps and LED unit significantly lead to higher degree of conversion in hybrid composites.

  20. RC T beams strengthened to shear with carbon fiber composites

    Directory of Open Access Journals (Sweden)

    L. A. Spagnolo JR

    Full Text Available This paper presents the experimental data of the behavior of reinforced concrete beams strengthened to shear with carbon fiber composites. The tests were composed of eight T beams, b w=15 cm, h=40 cm, flange width 40 cm, flange height 8 cm, and length 300 cm, divided into two series with the same longitudinal steel reinforcement and a reference beam without strengthening in each series. The beams had two types of arrangement of internal steel stirrups. The test variables were the internal and external geometric ratio of the transverse reinforcement and the mechanical ratio of carbon fiber composites stirrups. All the beams were loaded at two points. The strengthened beams were submitted to a preloading and the strengthening was applied to the cracked beam. All the beams were designed in order to guarantee shear failure, and the ultimate load of the strengthened beams was 36% to 54% greater than the reference beams. The Cracking Sliding Model applied to the strengthened beams was evaluated and showed good agreement with the experimental results.

  1. Quality correction factors of composite IMRT beam deliveries: Theoretical considerations

    International Nuclear Information System (INIS)

    Bouchard, Hugo

    2012-01-01

    Purpose: In the scope of intensity modulated radiation therapy (IMRT) dosimetry using ionization chambers, quality correction factors of plan-class-specific reference (PCSR) fields are theoretically investigated. The symmetry of the problem is studied to provide recommendable criteria for composite beam deliveries where correction factors are minimal and also to establish a theoretical limit for PCSR delivery k Q factors. Methods: The concept of virtual symmetric collapsed (VSC) beam, being associated to a given modulated composite delivery, is defined in the scope of this investigation. Under symmetrical measurement conditions, any composite delivery has the property of having a k Q factor identical to its associated VSC beam. Using this concept of VSC, a fundamental property of IMRT k Q factors is demonstrated in the form of a theorem. The sensitivity to the conditions required by the theorem is thoroughly examined. Results: The theorem states that if a composite modulated beam delivery produces a uniform dose distribution in a volume V cyl which is symmetric with the cylindrical delivery and all beams fulfills two conditions in V cyl : (1) the dose modulation function is unchanged along the beam axis, and (2) the dose gradient in the beam direction is constant for a given lateral position; then its associated VSC beam produces no lateral dose gradient in V cyl , no matter what beam modulation or gantry angles are being used. The examination of the conditions required by the theorem lead to the following results. The effect of the depth-dose gradient not being perfectly constant with depth on the VSC beam lateral dose gradient is found negligible. The effect of the dose modulation function being degraded with depth on the VSC beam lateral dose gradient is found to be only related to scatter and beam hardening, as the theorem holds also for diverging beams. Conclusions: The use of the symmetry of the problem in the present paper leads to a valuable theorem showing

  2. Experimental study on beam for composite CES structural system

    Science.gov (United States)

    Matsui, Tomoya

    2017-10-01

    Development study on Concrete Encase Steel (CES) composite structure system has been continuously conducted toward the practical use. CES structure is composed of steel and fiber reinforced concrete. In previous study, it was found that CES structure has good seismic performance from experimental study of columns, beam - column joints, shear walls and a two story two span frame. However, as fundamental study on CES beam could be lacking, it is necessary to understand the structural performance of CES beam. In this study, static loading tests of CES beams were conducted with experimental valuable of steel size, the presence or absence of slab and thickness of slab. And restoring characteristics, failure behavior, deformation behavior, and strength evaluation method of CES beam were investigated. As the results, it was found that CES beam showed stable hysteresis behavior. Furthermore it was found that the flexural strength of the CES beam could be evaluated by superposition strength theory.

  3. A refined model for piezoelectric composite beams

    International Nuclear Information System (INIS)

    Luschi, Luca; Pieri, Francesco

    2016-01-01

    This work presents and compares few simple one-dimensional models for the piezoelectric actuation and detection of beams. The 1D nature, which allows an easy embedding of the model in the classical Euler-Bernoulli beam equations, is obtained by adopting simplifying assumptions along directions of the cross-sectional plane. By changing such assumptions, different models can be built. Their validity is discussed and compared with results of FEM simulations for varying geometries. We show that commonly adopted models fail in a series of practical cases and propose a new model capable of accurately describing wide beams. (paper)

  4. The effect of different light-curing units on tensile strength and microhardness of a composite resin

    Directory of Open Access Journals (Sweden)

    Eduardo Batista Franco

    2007-12-01

    Full Text Available The aim of this study was to evaluate the influence of different light-curing units on the tensile bond strength and microhardness of a composite resin (Filtek Z250 - 3M/ESPE. Conventional halogen (Curing Light 2500 - 3M/ESPE; CL and two blue light emitting diode curing units (Ultraled - Dabi/Atlante; UL; Ultrablue IS - DMC; UB3 and UB6 were selected for this study. Different light intensities (670, 130, 300, and 600 mW/cm², respectively and different curing times (20s, 40s and 60s were evaluated. Knoop microhardness test was performed in the area corresponding to the fractured region of the specimen. A total of 12 groups (n=10 were established and the specimens were prepared using a stainless steel mold composed by two similar parts that contained a cone-shaped hole with two diameters (8.0 mm and 5.0 mm and thickness of 1.0 mm. Next, the specimens were loaded in tensile strength until fracture in a universal testing machine at a crosshead speed of 0.5 mm/min and a 50 kg load cell. For the microhardness test, the same matrix was used to fabricate the specimens (12 groups; n=5. Microhardness was determined on the surfaces that were not exposed to the light source, using a Shimadzu HMV-2 Microhardness Tester at a static load of 50 g for 30 seconds. Data were analyzed statistically by two-way ANOVA and Tukey's test (p<0.05. Regarding the individual performance of the light-curing units, there was similarity in tensile strength with 20-s and 40-s exposure times and higher tensile strength when a 60-s light-activation time was used. Regarding microhardness, the halogen lamp had higher results when compared to the LED units. For all light-curing units, the variation of light-exposure time did not affect composite microhardness. However, lower irradiances needed longer light-activation times to produce similar effect as that obtained with high-irradiance light-curing sources.

  5. Preparation of hyperbranched poly (amidoamine)-grafted graphene nanolayers as a composite and curing agent for epoxy resin

    Science.gov (United States)

    Gholipour-Mahmoudalilou, Meysam; Roghani-Mamaqani, Hossein; Azimi, Reza; Abdollahi, Amin

    2018-01-01

    Thermal properties of epoxy resin were improved by preparation of a curing agent of poly (amidoamine) (PAMAM) dendrimer-grafted graphene oxide (GO). Hyperbranched PAMAM-modified GO (GD) was prepared by a divergent dendrimer synthesis methodology. Modification of GO with (3-Aminopropyl)triethoxysilane (APTES), Michael addition of methacrylic acid, and amidation reaction with ethylenediamine results in the curing agent of GD. Then, epoxy resin was cured in the presence of different amounts of GD and the final products were compared with ethylenediamine-cured epoxy resin (E) in their thermal degradation temperature and char contents. Functionalization of GO with APTES and hyperbranched dendrimer formation at the surface of GO were evaluated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and thermogravimetric analysis (TGA) results. TGA results showed that the weight loss associated with chemical moieties in GONH2, GOMA, and GD is estimated to be 10.1, 12.2, and 14.1%, respectively. Covalent attachment of dendrimer at the surface of GO increases its thermal stability. TGA also showed that decomposition temperature and char content are higher for composites compared with E. Scanning and transmission electron microscopies show that flat and smooth graphene nanolayers are wrinkled in GO and re-stacking and flattening of nanolayers is observed in GD.

  6. The UV and Laser Aging for PMMA/BDK/Azo-dye Polymer Blend Cured by UV Light Beams

    International Nuclear Information System (INIS)

    Ahmad, A A; Omari, A M

    2015-01-01

    A polymeric-based solution blend composed of Azo-dye methyl red (MR) doped with polymethelmethacrelate (PMMA) solution, in addition, to the BenzylDimethylKetal (BDK) photoinitiator was made with optimum molar ratios and deposited on glass substrate by spin coating technique. The samples were then exposed to UV light beams in order to assist the layers polymerization by the proper exposure process. The photo chemical reaction occurred during the UV light polymerization process induces photo refractive changes which were presented as a function of wavelength or photon energy. Two main strong absorption peaks were observed in the films at around 330 nm (3.75 eV) and 500 nm (2.48 eV) for different curing time periods. This phenomenon enhances the films usage for optical data storage media at these two wavelengths. Since the deposited films were then useful as based layers for Read/Write optical data storage media, they were then tested by UV or laser Read/Write beams independently. The optical properties of the films were investigated while exposed to each beam. Finally, their optical properties were investigated as a function of aging time in order to relate the temporary and/or permanent light-exposure effect on the films compared to their optical properties before the light exposure. The films show a low absorbance at 630 nm (1.97 eV) and high absorbance at 480 nm (2.58 eV). This fact makes it possible to record holographic gratings in the polymeric film upon light exposure. In all cases the optical properties were evaluated by using the very sensitive, non destructive surface testing spectroscopic ellipsometry technique. The films were characterized in the spectral range of 300 to 1000 nm using Lorentz oscillator model with one oscillator centred at 4.15 eV. This study has been supported by the SEM and EDAX results to investigate the effect of the UV and visible beams on their optical properties. The results of this research determined the proper conditions for

  7. Effect of phenolic oligomer on adhesion of poly (ethylene terephthalate) film laminated steel sheets by Electron Beam Curing method

    International Nuclear Information System (INIS)

    Masuhara, Kenichi; Mori, Koji; Koshiishi, Kenji; Sasaki, Takashi.

    1995-01-01

    Adhesion of poly (ethylene terephthalate) film by Electron Beam Curing (EBC) method which can be thought as an energy-saving process was studied for the purpose of bestowing economically design and distinctness of image on thermosetting high molecular weight polyester precoated steel sheets. Adhesion of EB curable resins onto metal is generally poor. In this report, addition of EB curable phenolic resole oligomer with bifunctional acrylates to the top coat used for precoated steel was studied in order to increase the adhesion of an EB curable adhesive, and it was found that the phenolic oligomer is tremendously effective for the improvement of adhesion. The reasons why the phenolic oligomer provides excellent adhesion were 1) elongation at break of the top coat to which the phenolic oligomer is added is little decreased by EB irradiation, and the formability does not reduce. 2) As the phenolic oligomer is unevenly distributed to the surface layer of the top coat, it is suggested that the contact frequency of the phenolic oligomer to the EB curable adhesive is so high that graft polymerization between them is liable to occur. (author)

  8. Comparison between two methods to evaluate temperature changes produced by composite light curing units and polymerization techniques.

    Science.gov (United States)

    Loureiro, F H F; Consani, S; Guiraldo, R D; Consani, R L X; Berger, S B; Carvalho, R V; Correr-Sobrinho, L; Sinhoreti, M A C

    2011-10-01

    This study evaluated the temperature change into the pulp chamber during the light curing of composite resin by direct (bovine tooth) and indirect (matrix) methods. Direct method: fifty standardized cavities (2x2x2 mm) were prepared in bovine incisors, which were randomly assigned to evaluation of the temperature changes in the pulp chamber. Indirect method: temperature changes were evaluated through a dentine slice of 1.0 mm thickness in a elastomer cubic mold (2x2x2 mm). Filtek Z250 composite resin (3M/ESPE) was photo-activated using three light curing units: quartz-tungsten-halogen (QTH) by continuous, soft-start or intermittent light modulations; light emitting diode (LED); and plasma arc-curing (PAC). Ten groups (N.=10) were established according to technique evaluation and photo-activation methods. All experiments were carried out in a controlled environment (37 °C and 50 ± 10% relative humidity). The temperature changes were recorded using a digital thermometer attached to a type-K thermocouple in contact with the dentin slice (indirect method) or in contact with the axial wall (dentin) of pulp chamber (direct method). The results were submitted to ANOVA and Tukey's test (α=0.05). Temperature changes were statistically higher for the matrix indirect method (2.56 ºC) than bovine teeth direct method (1.17ºC). The change temperature was statistically higher for the PAC (1.77 ºC) when compared to other photo-activation modes in bovine teeth direct method. The two methods of temperature evaluation were different, however indirect method detected the higher temperature increase. Higher energy density arising from the light curing units and polymerization techniques promoted higher temperature increase.

  9. Analysis of Mode II Crack in Bilayered Composite Beam

    Science.gov (United States)

    Rizov, Victor I.; Mladensky, Angel S.

    2012-06-01

    Mode II crack problem in cantilever bilayered composite beams is considered. Two configurations are analyzed. In the first configuration the crack arms have equal heights while in the second one the arms have different heights. The modulus of elasticity and the shear modulus of the beam un-cracked part in the former case and the moment of inertia in the latter are derived as functions of the two layers characteristics. The expressions for the strain energy release rate, G are obtained on the basis of the simple beam theory according to the hypotheses of linear elastic fracture mechanics. The validity of these expressions is established by comparison with a known solution. Parametrical investigations for the influence of the moduli of elasticity ratio as well as the moments of inertia ratio on the strain energy release rate are also performed. The present article is a part of comprehensive investigation in Fracture mechanics of composite beams.

  10. Fluorescence Characterization of Cure and Water-Uptake in Polymers and Composites

    Science.gov (United States)

    1994-06-01

    the different wavelength DDS) in the stoichiometric mixture of DDS and EDDA calibration in both instruments as well as to some (ethylene dioxyl...diethyl amine) were obtained before temperature dependence of the excitation maxima. and after 1 h cure at 120°C. EDDA is an aliphatic However, the overall

  11. Shear behavior of reinforced Engineered Cementitious Composites (ECC) beams

    DEFF Research Database (Denmark)

    Paegle, Ieva; Fischer, Gregor

    2010-01-01

    This paper describes an experimental investigation of the shear behavior of beams consisting of steel reinforced Engineered Cementitious Composites (ECC). Based on the strain hardening and multiple cracking behavior of ECC, this study investigates the extent to which ECC can improve the shear...... capacity of beams loaded primarily in shear and if ECC can partially or fully replace the conventional transverse steel reinforcement in beams. However, there is a lack of understanding of how the fibers affect the shear carrying capacity and deformation behavior of structural members if used either...

  12. Surface modification of silica particles and its effects on cure and mechanical properties of the natural rubber composites

    Energy Technology Data Exchange (ETDEWEB)

    Theppradit, Thawinan [Program in Petrochemistry and Polymer Science, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Prasassarakich, Pattarapan [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Poompradub, Sirilux, E-mail: sirilux.p@chula.ac.th [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

    2014-12-15

    The efficiency of modified silica (SiO{sub 2}) particles in the reinforcement of natural rubber (NR) vulcanizates was evaluated. The SiO{sub 2} particles were synthesized via a sol–gel reaction using tetraethyl orthosilicate as the precursor, and then the formed SiO{sub 2} particles were modified with methyl, vinyl or aminopropyl groups using methyltriethoxysilane, vinyltriethoxysilane or aminopropyltrimethoxysilane, respectively. Fourier transform infrared spectroscopy and elemental analysis confirmed the successful modification of the surface of the silica particles. The water contact angle measurement revealed the greater hydrophobicity of the three modified silica preparations compared to the unmodified SiO{sub 2}. NR vulcanizates filled with modified SiO{sub 2} particles were prepared and the mechanical, thermal and dynamic mechanical properties of composites were investigated. The morphology of composite materials was also investigated by scanning electron microscopy. The modified SiO{sub 2} particles were well dispersed in the NR matrix leading to the good compatibility between the rubber and filler, and so an improved cure, mechanical, thermal and dynamic mechanical properties of the composite vulcanizate materials. - Highlights: • Modification of SiO{sub 2} particles by MTES, VTES and APTES. • Improvement of hydrophobicity of SiO{sub 2} particle and compatibility between SiO{sub 2} and rubbery matrix. • Improvement of cure, mechanical, thermal, dynamic mechanical properties of NR vulcanizates.

  13. 3-dimensional free standing micro-structures by proton beam writing of Su 8-silver nanoParticle polymeric composite

    Science.gov (United States)

    Igbenehi, H.; Jiguet, S.

    2012-09-01

    Proton beam lithography a maskless direct-write lithographic technique (well suited for producing 3-Dimensional microstructures in a range of resist and semiconductor materials) is demonstrated as an effective tool in the creation of electrically conductive freestanding micro-structures in an Su 8 + Nano Silver polymer composite. The structures produced show non-ohmic conductivity and fit the percolation theory conduction model of tunneling of separated nanoparticles. Measurements show threshold switching and a change in conductivity of at least 4 orders of magnitude. The predictable range of protons in materials at a given energy is exploited in the creation of high aspect ratio, free standing micro-structures, made from a commercially available SU8 Silver nano-composite (GMC3060 form Gersteltec Inc. a negative tone photo-epoxy with added metallic nano-particles(Silver)) to create films with enhanced electrical properties when exposed and cured. Nano-composite films are directly written on with a finely focused MeV accelerated Proton particle beam. The energy loss of the incident proton beams in the target polymer nano- composite film is concentrated at the end of its range, where damage occurs; changing the chemistry of the nano-composite film via an acid initiated polymerization - creating conduction paths. Changing the energy of the incident beams provide exposed regions with different penetration and damage depth - exploited in the demonstrated cantilever microstructure.

  14. The Properties of SBR/ENR50 Blend Containing Nanoclay/Carbon Black Dual Filler System Cured by Electron Beam

    Directory of Open Access Journals (Sweden)

    Sima Ahmadi-Shooli

    2017-05-01

    Full Text Available Nanocomposites based on an SBR/ENR50 rubber blend with the blend ratio of 50/50 using Cloisite 15A nanoclay (5 and 10 phr and carbon black (20 phr were prepared by melt mixing process. The rubber compounds were crosslinked by electron beam irradiation process at 50 and 100 kGy doses. A reference sample containing carbon black at 35 phr was prepared using a conventional sulphur curing system. The gel content of the samples was specified using gel fraction measurement. The results showed the maximum gel content for the sample having 5 phr nanoclay and 20 phr carbon black. The dynamic mechanical properties, including the storage modulus, loss modulus, and loss factor, of the nanocomposites were evaluated using dynamic mechanical analysis (DMA tests. The results indicated that, in spite of a well dispersed nanoclay in samples containing 10 phr nanoclay and 20 phr carbon black, a minimum loss factor was observed in the sample containing 5 phr nanoclay and 20 phr carbon black at 100 kGy. On the other hand, the storage modulus of the reference sample was found to be higher than that of the sample with 5 phr nanoclay and 20 phr carbon black. The mechanical properties, including the tensile strength, stress at 100%, 200%, and 300% elongation and the percentage of elongation were measured by a tensile machine. The results showed an increase in tensile strength and the stress at different elongations for a sample with 5 phr nanoclay and 20 phr carbon black compared to the reference sample. In the corresponding SEM images of the samples having nanoclay and carbon black irradiated at 100 kGy a significantly higher surface roughness was observed.

  15. Influence of polymerization time and depth of cure of resin composites determined by Vickers hardness

    Directory of Open Access Journals (Sweden)

    Marco Lombardini

    2012-01-01

    Conclusion: Among the materials tested, the nanofilled and the nanohybrid resin composites were rather insensible to thickness variations. Miicrohybrid composites, instead, had features different from one another.

  16. Air-Cured Fiber-Cement Composite Mixtures with Different Types of Cellulose Fibers

    Directory of Open Access Journals (Sweden)

    Ali Murat Soydan

    2018-01-01

    Full Text Available This present study was carried out to check the feasibility of different cellulose fibers obtained from cropped virgin cellulose, blenched eucalyptus, and araucaria pulps through different new environmentally friendly curing processes for fiber-cement production. The aim is to introduce the different sources of cellulose fibers with lower cost to produce the “fiber-cement without autoclave” (FCWA. The slurries used in the experiments contain approximately 8% wt. of cellulose. The influence of the waste marble powder addition to the cement mixture was also studied. The physical and mechanical properties of the products which were prepared with this method under different curing conditions were investigated. The mechanical properties of eucalyptus cellulose appear to offer the best combination, especially after longer air-cure cycles. The results showed that the production of FCWA is very economical by using waste marble powders. And moreover, two new types of cellulose fibers (eucalyptus and araucaria celluloses; EuC and ArC, resp., which provide a better density and packing in the fiber-cement leading to better modulus of rupture (MOR and modulus of elasticity (MOE values as virgin cellulose (ViC, are very usable for production of the fiber-cement in industrial scale.

  17. ALL NATURAL COMPOSITE SANDWICH BEAMS FOR STRUCTURAL APPLICATIONS. (R829576)

    Science.gov (United States)

    As part of developing an all natural composite roof for housing application,structural panels and unit beams were manufactured out of soybean oil based resinand natural fibers (flax, cellulose, pulp, recycled paper, chicken feathers)using vacuum assisted resin tran...

  18. Coating compositions hardenable by ionization beams

    International Nuclear Information System (INIS)

    Chaudhari, D.; Haering, E.; Dobbelstein, A.; Hoselmann, W.

    1976-01-01

    Coating compositions hardenable by ionizing radiation are described which contain as binding agents a mixture of at least 1 unsaturated olefin compound containing urethane groups, and at least 1 further unsaturated olefin compound that may be copolymerized. The unsaturated olefin compound containing the urethane groups is a reaction product of a compound containing carboxylic acid groups and a compound containing at least 1 isocyanate group where the mixture of the two olefins may contain conventional additives of the lacquer industry. 6 claims, no drawings

  19. Vibration suppression of composite laminated beams using distributed piezoelectric patches

    International Nuclear Information System (INIS)

    Foda, M A; Almajed, A A; ElMadany, M M

    2010-01-01

    The focus of this paper is to develop an analytical and straightforward approach to suppress the steady state transverse vibration of a symmetric cross-ply laminated composite beam that is excited by an external harmonic force. This is achieved by bonding patches of piezoelectric material at selected locations along the beam. The governing equations for the system are formulated and the dynamic Green's functions are used to obtain an exact solution for the problem. A scheme is proposed for determining the values of the driving voltages, the dimensions of the PZT patches and their locations along the beam, in order to confine the vibration in a certain chosen region where the vibration is not harmful and leave the other chosen region stationary or vibrating with very small amplitudes. Beams with different boundary conditions are considered. Numerical case studies are presented to verify the utility of the proposed scheme

  20. Coating compositions hardenable by ionization beams

    International Nuclear Information System (INIS)

    Chaudhari, D.; Haering, E.; Dobbelstein, A.; Hoselmann, W.

    1976-01-01

    Coating compositions hardenable by ionizing radiation comprise as binding agents a mixture of A. at least 1 unsaturated olefin compound containing urethane groups, and B. at least 1 further unsaturated olefin compound that may be copolymerized. The unsaturated olefin compound A. containing the urethane groups in a reaction product of (a) a compound of the general formula (CHR 1 = CR 2 COOCH 2 CH(OH)CH 2 O CO-)/sub n/R where n is 1 or 2, where R stands for a straight chain or branched alkyl group of valence n, where R 1 is hydrogen, methyl; or the group -COOCH 2 CH(OH)CH 2 OCOR 3 - where R 3 is a monovalent alkyl residue and where R 2 is hydrogen or methyl, and (b) a compound containing at least 1 isocyanate group where the mixture of (A) and (B) may contain conventional additives of the lacquer industry. 6 claims

  1. Interfacial shear behavior of composite flanged concrete beams

    Directory of Open Access Journals (Sweden)

    Moataz Awry Mahmoud

    2014-08-01

    Full Text Available Composite concrete decks are commonly used in the construction of highway bridges due to their rapid constructability. The interfacial shear transfer between the top slab and the supporting beams is of great significance to the overall deck load carrying capacity and performance. Interfacial shear capacity is directly influenced by the distribution and the percentage of shear connectors. Research and design guidelines suggest the use of two different approaches to quantify the required interfacial shear strength, namely based on the maximum compressive forces in the flange at mid span or the maximum shear flow at the supports. This paper investigates the performance of flanged reinforced concrete composite beams with different shear connector’s distribution and reinforcing ratios. The study incorporated both experimental and analytical programs for beams. Key experimental findings suggest that concentrating the connectors at the vicinity of the supports enhances the ductility of the beam. The paper proposes a simple and straight forward approach to estimate the interfacial shear capacity that was proven to give good correlation with the experimental results and selected code provisions. The paper presents a method to predict the horizontal shear force between precast beams and cast in-situ slabs.

  2. Gelatin/piassava composites treated by Electron Beam Radiation

    International Nuclear Information System (INIS)

    Takinami, Patricia Yoko Inamura; Shimazaki, Kleber; Moura, Esperidiana Augusta Barretos de; Mastro, Nelida Lucia del; Colombo, Maria Aparecida

    2010-01-01

    Piassava (Attalea funifera Mart) fiber has been investigated as reinforcement for polymer composites with potential for practical applications. The purpose of the present work was to assess the behavior of specimens of piassava fiber and gelatin irradiated with electron beam at different doses and percentage. The piassava/gelatin specimens were made with 5 and 10% (w/w) piassava fiber, gelatin 25% (w/w), glycerin as plasticizer and acrylamide as copolymer. The samples were irradiated up to 40 kGy using an electron beam accelerator, at room temperature in presence of air. Preliminary results showed mechanical properties enhancement with the increase in radiation dose. (author)

  3. Composition of mortar as a function of distance to the brick-mortar interface : A study on the formation of cured mortar structure in masonry using NMR, PFM and XRD

    NARCIS (Netherlands)

    Brocken, H.J.P.; Larbi, J.A.; Pel, L.; Pers, N.M. van der

    1999-01-01

    The formation of cured mortar structure in masonry was studied using multiple experimental techniques. Starting with fresh mortar, nuclear magnetic resonance (NMR) was used to measure the water extraction during brick laying. After curing, the composition of cured mortar was investigated with

  4. Full in-vitro analyses of new-generation bulk fill dental composites cured by halogen light.

    Science.gov (United States)

    Tekin, Tuçe Hazal; Kantürk Figen, Aysel; Yılmaz Atalı, Pınar; Coşkuner Filiz, Bilge; Pişkin, Mehmet Burçin

    2017-08-01

    The objective of this study was to investigate the full in-vitro analyses of new-generation bulk-fill dental composites cured by halogen light (HLG). Two types' four composites were studied: Surefill SDR (SDR) and Xtra Base (XB) as bulk-fill flowable materials; QuixFill (QF) and XtraFill (XF) as packable bulk-fill materials. Samples were prepared for each analysis and test by applying the same procedure, but with different diameters and thicknesses appropriate to the analysis and test requirements. Thermal properties were determined by thermogravimetric analysis (TG/DTG) and differential scanning calorimetry (DSC) analysis; the Vickers microhardness (VHN) was measured after 1, 7, 15 and 30days of storage in water. The degree of conversion values for the materials (DC, %) were immediately measured using near-infrared spectroscopy (FT-IR). The surface morphology of the composites was investigated by scanning electron microscopes (SEM) and atomic-force microscopy (AFM) analyses. The sorption and solubility measurements were also performed after 1, 7, 15 and 30days of storage in water. In addition to his, the data were statistically analyzed using one-way analysis of variance, and both the Newman Keuls and Tukey multiple comparison tests. The statistical significance level was established at pfill, resin-based dental composites. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Effect of curing light emission spectrum on the nanohardness and elastic modulus of two bulk-fill resin composites.

    Science.gov (United States)

    Issa, Yaser; Watts, David C; Boyd, Daniel; Price, Richard B

    2016-04-01

    To determine the nanohardness and elastic moduli of two bulk-fill resin based composites (RBCs) at increasing depths from the surface and increasing distances laterally from the center after light curing. Two bulk-fill dental RBCs: Tetric EvoCeram Bulk Fill (TECBF) and Filtek Bulk Fill Flowable (FBFF) were light cured in a metal mold with a 6mm diameter and a 10mm long semi-circular notch. The RBCs were photo-polymerized for 10s using a light emitting diode (LED) Bluephase Style curing light, with the original light probe that lacked the homogenizer. This light has two blue light and one violet light LED emitters. By changing the probe orientation over the mold, the light output from only two LEDs reached the RBC. Measurements were made using: (i) the light from one violet and one blue LED, and (ii) the light from the two blue LEDs. Five specimens of each RBC were made using each LED orientation (total 20 specimens). Specimens were then stored in the dark at 37°C for 24h. Fifty indents were made using an Agilent G200 nanoindentor down to 4mm from the surface and 2.5mm right and left of the centerline. The results were analyzed (alpha=0.05) using multiple paired-sample t-tests, ANOVA, Bonferroni post-hoc tests, and Pearson correlations. The elastic modulus and nanohardness varied according to the depth and the distance from the centerline. For TECBF, no significant difference was found between the spatial variations in the elastic modulus or hardness values when violet-blue or blue-blue LEDs were used. For FBFF, the elastic modulus and nanohardness on the side exposed to the violet emitter were significantly less than the side exposed to the blue emitter. A strong correlation between nanohardness and elastic modulus was found in all groups (r(2)=0.9512-0.9712). Resin polymerization was not uniform throughout the RBC. The nanohardness and elastic modulus across two RBC materials were found to decline differently according to the orientation of the violet and blue

  6. Degree of conversion and microhardness of TPO-containing resin-based composites cured by polywave and monowave LED units.

    Science.gov (United States)

    Santini, Ario; Miletic, Vesna; Swift, Michael D; Bradley, Mark

    2012-07-01

    To determine the degree of conversion (DC) and Knoop microhardness (KHN) of resin-based composites (RBCs) containing trimethylbenzoyl-diphenylphosphine oxide (TPO) cured by polywave or monowave LED light-curing units (LCUs). Three groups (each n = 5) of Tetric EvoCeram (Ivoclar Vivadent), Vit-l-escence (Ultradent) and Herculite XRV Ultra (Kerr) were prepared in Teflon moulds (5mm in diameter and 2mm thick) and cured with polywave Bluephase(®) G2 (Ivoclar Vivadent), polywave Valo (Ultradent) or monowave Bluephase(®) (Ivoclar Vivadent; control) resulting in 9 groups. DC and KHN were determined using micro-Raman spectroscopy and Knoop microhardness, respectively. High-performance liquid chromatography and nuclear magnetic resonance spectroscopy were used to confirm the presence or absence of TPO in the three uncured materials. Data were statistically analysed using two-way and one-way ANOVA and DC and KHN were correlated using Pearson's correlation (α = 0.05). TPO was confirmed in Tetric EvoCeram and Vit-l-escence but not in Herculite XRV Ultra. All three LCUs produced comparable KHN for Tetric EvoCeram and Herculite XRV Ultra (p > 0.05). Both polywave LCUs resulted in significantly higher KHN for Vit-l-escence and higher DC in Tetric EvoCeram and Vit-l-escence than the monowave Bluephase(®) (p Conversely, Bluephase(®) showed higher DC than the two polywave LCUs in Herculite XRV Ultra (p conversion and KHN in the two TPO-containing RBCs, but not in Herculite XRV Ultra. DC and KHN were linearly correlated in all three RBCs. Vit-l-escence showed the highest DC and KHN of the three materials tested. The use of polywave LEDs significantly improves both the DC and KHN of materials which contain TPO. This should be taken into account when curing bleached shades of RBCs even if the manufacturers do not indicate the presence of TPO in their materials. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Long Out-time, Out-of-Autoclave Cure Composites, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — As the size of composite parts exceed that of even the largest autoclaves, new out-of-autoclave processes and materials are necessary to achieve the same level of...

  8. Long Out-time, Out-of-Autoclave Cure Composites, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — As the size of composite parts exceed that of even the largest autoclaves, new out-of-autoclave processes and materials are necessary to achieve the same level of...

  9. Application of electron-chemical curing in the production of thin composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Kopetchenov, V.; Shik, V.; Konev, V.; Kurapov, A.; Misin, I.; Gavrilov, V.; Malik, V. (Polyrad Research and Production Co., Moscow (Russian Federation))

    Thousands of tons of various thin composite materials in rolls for electrotechnical and domestic application including a whole range of electrical insulating materials, such as varnished and polymer fabrics, glass-micatapes, prepregs, thin laminated plastics and clad laminates, materials for decorative and domestic purposes - pressure sensitive adhesive tape and laminates, covering and finishing compositions based on fabrics, films and papers are produced. An important advantage of the electron-chemical processing in the production of composite materials is an essential energy saving (reduction of energy consumption 3-5 times). Absence of the organic diluents in binders decreases fire and explosion hazards of the production and sufficiently decreases danger for the environment of the technology used. Research and Production Company ''Polyrad'' is engaged in the development of technologies and equipment for the production of thin composite materials by the Electron-Chemical Method. (author).

  10. Application of electron-chemical curing in the production of thin composite materials

    International Nuclear Information System (INIS)

    Kopetchenov, V.; Shik, V.; Konev, V.; Kurapov, A.; Misin, I.; Gavrilov, V.; Malik, V.

    1993-01-01

    Thousands of tons of various thin composite materials in rolls for electrotechnical and domestic application including a whole range of electrical insulating materials, such as varnished and polymer fabrics, glass-micatapes, prepregs, thin laminated plastics and clad laminates, materials for decorative and domestic purposes - pressure sensitive adhesive tape and laminates, covering and finishing compositions based on fabrics, films and papers are produced. An important advantage of the electron-chemical processing in the production of composite materials is an essential energy saving (reduction of energy consumption 3-5 times). Absence of the organic diluents in binders decreases fire and explosion hazards of the production and sufficiently decreases danger for the environment of the technology used. Research and Production Company ''Polyrad'' is engaged in the development of technologies and equipment for the production of thin composite materials by the Electron-Chemical Method. (author)

  11. Radiation-curing of acrylate composites including carbon fibres: A customized surface modification for improving mechanical performances

    International Nuclear Information System (INIS)

    Martin, Arnaud; Pietras-Ozga, Dorota; Ponsaud, Philippe; Kowandy, Christelle; Barczak, Mariusz; Defoort, Brigitte; Coqueret, Xavier

    2014-01-01

    The lower transverse mechanical properties of radiation-cured acrylate-based composites reinforced with carbon-fibre with respect to the thermosettable analogues was investigated from the viewpoint of chemical interactions at the interface between the matrix and the carbon material. XPS analysis of representative commercial carbon fibres revealed the presence of a significant amount of chemical functions potentially exerting an adverse effect on the initiation and propagation of the free radical polymerization initiated under high energy radiation. The EB-induced polymerization of n-butyl acrylate as a simple model monomer was conducted in the presence of various aromatic additives exhibiting a strong inhibiting effect, whereas thiols efficiently sensitize the initiation mechanism and undergo transfer reactions. A method based on the surface modification of sized fibres by thiomalic acid is proposed for overcoming the localized inhibition phenomenon and for improving the mechanical properties of the resulting acrylate-based composites. - Highlights: • Surface functions of C-fibres are analyzed for their effect on radical reaction. • Irradiation of nBu-acrylate in presence of aromatic additives reveals inhibition. • Thiol groups sensitize the radiation-initiated polymerization of nBu-acrylate. • Modification of C-fibres with thiomalic acid enhances composite properties

  12. Evaluation of effect of different disposable infection control barriers on light intensity of light-curing unit and microhardness of composite - An in vitro study.

    Science.gov (United States)

    Khode, Rajiv Tarachand; Shenoi, Pratima Ramakrishna; Kubde, Rajesh R; Makade, Chetana S; Wadekar, Kanchan D; Khode, Priyanka Tarachand

    2017-01-01

    This study evaluated effect of infection control barriers on light intensity (LI) of light-curing unit (LCU) and microhardness of composite. Four different disposable barriers ( n = 30) were tested against the control. LI for each barrier was measured with Lux meter. One hundred and fifty Teflon molds were equally divided into five groups of thirty each. Composite was filled in bulk in these molds and cured without and with barrier. Microhardness was evaluated on top and bottom surface of composite specimen with microhardness testing machine and hardness ratio (HR) was derived. One-way analysis of variance, Tukey's honestly significant difference test, and paired t -test using SPSS version 18 software. All barriers had significantly reduced the baseline LI of LCU ( P glove pieces (LCGP) significantly reduced the microhardness of the composite ( P < 0.05). However, HR determined inadequate curing only with LCGP. Although entire tested barrier significantly reduced the LI; none, except LCGP markedly affected the degree of cure of the composite.

  13. Composite Beam Theory with Material Nonlinearities and Progressive Damage

    Science.gov (United States)

    Jiang, Fang

    Beam has historically found its broad applications. Nowadays, many engineering constructions still rely on this type of structure which could be made of anisotropic and heterogeneous materials. These applications motivate the development of beam theory in which the impact of material nonlinearities and damage on the global constitutive behavior has been a focus in recent years. Reliable predictions of these nonlinear beam responses depend on not only the quality of the material description but also a comprehensively generalized multiscale methodology which fills the theoretical gaps between the scales in an efficient yet high-fidelity manner. The conventional beam modeling methodologies which are built upon ad hoc assumptions are in lack of such reliability in need. Therefore, the focus of this dissertation is to create a reliable yet efficient method and the corresponding tool for composite beam modeling. A nonlinear beam theory is developed based on the Mechanics of Structure Genome (MSG) using the variational asymptotic method (VAM). The three-dimensional (3D) nonlinear continuum problem is rigorously reduced to a one-dimensional (1D) beam model and a two-dimensional (2D) cross-sectional analysis featuring both geometric and material nonlinearities by exploiting the small geometric parameter which is an inherent geometric characteristic of the beam. The 2D nonlinear cross-sectional analysis utilizes the 3D material models to homogenize the beam cross-sectional constitutive responses considering the nonlinear elasticity and progressive damage. The results from such a homogenization are inputs as constitutive laws into the global nonlinear 1D beam analysis. The theoretical foundation is formulated without unnecessary kinematic assumptions. Curvilinear coordinates and vector calculus are utilized to build the 3D deformation gradient tensor, of which the components are formulated in terms of cross-sectional coordinates, generalized beam strains, unknown warping

  14. From Composition to Cure: A Systems Engineering Approach to Anticancer Drug Carriers.

    Science.gov (United States)

    MacEwan, Sarah R; Chilkoti, Ashutosh

    2017-06-06

    The molecular complexity and heterogeneity of cancer has led to a persistent, and as yet unsolved, challenge to develop cures for this disease. The pharmaceutical industry focuses the bulk of its efforts on the development of new drugs, but an alternative approach is to improve the delivery of existing drugs with drug carriers that can manipulate when, where, and how a drug exerts its therapeutic effect. For the treatment of solid tumors, systemically delivered drug carriers face significant challenges that are imposed by the pathophysiological barriers that lie between their site of administration and their site of therapeutic action in the tumor. Furthermore, drug carriers face additional challenges in their translation from preclinical validation to clinical approval and adoption. Addressing this diverse network of challenges requires a systems engineering approach for the rational design of optimized carriers that have a realistic prospect for translation from the laboratory to the patient. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Electron beam irradiation effects on carbon fiber reinforced PEEK composite

    International Nuclear Information System (INIS)

    Sasuga, Tsuneo; Hagiwara, Miyuki; Odajima, Tosikazu; Sakai, Hideo; Nakakura, Toshiyuki; Masutani, Masahiro.

    1987-03-01

    Carbon fiber(CF) reinforced composites, using polyarylether-sulfone (PES) or polyarylether-ether-ketone (PEEK) as matrix material, were prepared and their electron beam irradiation effects were studied on the basis of changes in mechanical and dynamic viscoelastic properties and observation of fracture surfaces. The flexural strength of PES-CF composite decreased to 70 % of the initial strength after the irradiation of 3 MGy and 40 % after 15 MGy. The change in the profile of stress-strain (S-S) curves and fractographic observation by electron microscopy indicated that this composite irradiated with over 3 MGy was fractured by delamination caused by to the degradation of matrix polymer. The mechanical properties of PEEK-CF composite were scarcely decreased even after irradiated up to 180 MGy and this composite showed very high radiation resistance. The change in the profile of S-S curves and fractographic observation showed that this composite fractured due to destruction of fiber in the dose range less than 180 MGy, indicating that PEEK was excellent matrix material used in high radiation field. PEEK-PES-CF composite which was composed of the carbon fibers coated with PES solution showed less radiation resistance compared with PEEK-CF composite; the flexural strength decreased to 85 % of the initial value after the irradiation with 90 MGy. It was revealed from the changes in the profile of S-S curve that the specimen irradiated over 120 MGy was fractured due to not only fiber destruction but delamination. Deterioration mechanism of PEEK-PES-CF composite was studied by dynamic viscoelastic measurements in connection with the damage on matrix-fiber interface. It was suggested that the deterioration in mechanical properties of this composite was caused by the degradation of PES that coated on the surface of the carbon fibers. (author)

  16. Response behavior of an epoxy resin/amine curing agent/carbon black composite film to various solvents

    Energy Technology Data Exchange (ETDEWEB)

    Luo Yanling [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China)]. E-mail: luoyl0401@yahoo.com.cn; Li Zhanqing [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China); Lan Wenxiang [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China)

    2007-04-25

    A novel polymer based sensitive film was prepared from thermosetting epoxy resins (EP) filled with carbon blacks. The curing reaction of amine curing agents with epoxy resins and the response of the curing resultants to solvent vapors were dealt with. The influence of the types and content of carbon blacks and curing agents, and curing temperatures and time on curing reactions and response selectivity of the conductive films were investigated. The structural characterization was conducted on a Fourier transform infrared spectrophotometer (FTIR). The results indicated that the conductive films showed high response selectivity to polar solvent vapors, especially to chloroform vapor, while no response was observed in non-polar solvent vapors. The responsivity of the film increased with the decreased carbon black contents. The film filled with acetylene carbon black gave an optimal response, with responsivity of about 700 times. The response performances were improved with the amount of curing agents increased, and an optimal response appeared at the amount of the curing agent of 8%. The film's responsivity was remarkably enhanced, the reversibility property, however, rapidly declined in the order of diethyleneltriamine < triethylenetetramine < ethylenediamine. The curing reaction tended to complete with the curing temperature elevated and the curing time prolonged. But the response performance dropped because of over cross-linking as the temperature was too high or the time was too long.

  17. Response behavior of an epoxy resin/amine curing agent/carbon black composite film to various solvents

    International Nuclear Information System (INIS)

    Luo Yanling; Li Zhanqing; Lan Wenxiang

    2007-01-01

    A novel polymer based sensitive film was prepared from thermosetting epoxy resins (EP) filled with carbon blacks. The curing reaction of amine curing agents with epoxy resins and the response of the curing resultants to solvent vapors were dealt with. The influence of the types and content of carbon blacks and curing agents, and curing temperatures and time on curing reactions and response selectivity of the conductive films were investigated. The structural characterization was conducted on a Fourier transform infrared spectrophotometer (FTIR). The results indicated that the conductive films showed high response selectivity to polar solvent vapors, especially to chloroform vapor, while no response was observed in non-polar solvent vapors. The responsivity of the film increased with the decreased carbon black contents. The film filled with acetylene carbon black gave an optimal response, with responsivity of about 700 times. The response performances were improved with the amount of curing agents increased, and an optimal response appeared at the amount of the curing agent of 8%. The film's responsivity was remarkably enhanced, the reversibility property, however, rapidly declined in the order of diethyleneltriamine < triethylenetetramine < ethylenediamine. The curing reaction tended to complete with the curing temperature elevated and the curing time prolonged. But the response performance dropped because of over cross-linking as the temperature was too high or the time was too long

  18. [Bonding of visible light cured composite resins to glass ionomer and Cermet cements].

    Science.gov (United States)

    Kakaboura, A; Vougiouklakis, G

    1990-04-01

    The "sandwich" technique involves combination of composite resins to etched glassionomer cements, is used today in restorative dentistry. The purpose of this study is to evaluate the bond strength between several composite resins and glass ionomer or cerment cements. Cylindrical specimens of the cements Ketac-Silver, Ionobond and GC-Lining Ce-ment were inserted in a mold and their flat free surfaces were etched for 30". Cylindrical plastic tubes were set upon each one of these surfaces and filled with the Composite resins Durafill, Brilliant Lux, Estilux posterior, Estilux posterior CVS and Herculite XR. Half of the specimens transferred in tap water for 24 hours and the others after thermocycling in the first month, kept for 4 months. Shear bond strengths were determined in Monsanto Testing Machine and some fractured surfaces were examined under SEM. The results of this investigation indicate that this technique produces bond strengths between composite resins and glassioners and the combination type of resin and type of cement, affects the values of the strength. Glass cermeet--small particle resin provides the most effective strength and glass ionomer--microfill resins the least. Storage time and thermocycling don't significantly effect the bond strength. SEM examination showed that all fracture failures were obtained in the cement while the opposite resin surfaces were covered with particles of the cements.

  19. Translucency, opalescence and light transmission characteristics of light-cured resin composites.

    Science.gov (United States)

    Arimoto, Ayako; Nakajima, Masatoshi; Hosaka, Keiichi; Nishimura, Kozo; Ikeda, Masaomi; Foxton, Richard M; Tagami, Junji

    2010-11-01

    To evaluate the translucency, opalescence and light transmission characteristics of resin composites with different thicknesses. Disks of three resin composites (Estelite∑, Beautifil II, Clearfil Majesty) of A2 shade were prepared in diameter of 10mm with various thicknesses (0.5mm, 1.0mm and 2.0mm). Color was measured according to CIELAB color scale on a reflection spectrophotometer and a color haze meter, and translucency parameter (TP) and opalescence parameter (OP) were calculated. Using the distribution graphs of transmitted light intensity on a goniophotometer, diffusion factor (DF) as an indicator for a diffuse transmission property and peak gain (G0) for a straight-line transmission property were calculated. The TP and G0 values significantly decreased in the order: 0.5mm>1.0mm>2.0mm thickness (popalescence (OP) of resin composites had a significant correlation with a diffuse transmission property (DF). When more than 1.0mm thickness of resin composites, translucency and opalescence were influenced by the thickness, in which translucency significantly decreased and opalescence significantly increased. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. Cure Cycle Design Methodology for Fabricating Reactive Resin Matrix Fiber Reinforced Composites: A Protocol for Producing Void-free Quality Laminates

    Science.gov (United States)

    Hou, Tan-Hung

    2014-01-01

    For the fabrication of resin matrix fiber reinforced composite laminates, a workable cure cycle (i.e., temperature and pressure profiles as a function of processing time) is needed and is critical for achieving void-free laminate consolidation. Design of such a cure cycle is not trivial, especially when dealing with reactive matrix resins. An empirical "trial and error" approach has been used as common practice in the composite industry. Such an approach is not only costly, but also ineffective at establishing the optimal processing conditions for a specific resin/fiber composite system. In this report, a rational "processing science" based approach is established, and a universal cure cycle design protocol is proposed. Following this protocol, a workable and optimal cure cycle can be readily and rationally designed for most reactive resin systems in a cost effective way. This design protocol has been validated through experimental studies of several reactive polyimide composites for a wide spectrum of usage that has been documented in the previous publications.

  1. Dynamic Mechanical Analysis of E-Beam and Thermally Curable IPN Thermosets

    National Research Council Canada - National Science Library

    Jensen, Robert

    2002-01-01

    ... composites in a single step. Because of the complexity and thickness of composite integral armor structures, e-beam curing is an attractive processing method for Future Combat System applications, and the development...

  2. Radiation curing of mixtures of diallylphthalate prepolymer and vinyl monomer, 9

    International Nuclear Information System (INIS)

    Gotoda, Masao; Kitada, Yoshinori.

    1975-01-01

    Radiation curing, mainly by electron beams was studied with mixtures of low molecular weight diallylphthalate prepolymer (DAPsub(p).L) and vinyl monomers with special reference to their workability. Among the vinyl monomers, acrylonitrile gave a solution of low viscosity and methyl acrylate gave a solution of low dose curing. Radiation curing of DAPsub(p).L/vinyl monomer mixtures impregnated in wood was also tried. To obtain uniform wood-polymer composites, γ-irradiation after impregnation at 10 kg/cm 2 was found to be required for thick plate (110 mm), while electron beam irradiation after impregnation at normal pressure was sufficient for thin plate. (author)

  3. Element free Galerkin formulation of composite beam with longitudinal slip

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Dzulkarnain; Mokhtaram, Mokhtazul Haizad [Department of Civil Engineering, Universiti Selangor, Bestari Jaya, Selangor (Malaysia); Badli, Mohd Iqbal; Yassin, Airil Y. Mohd [Faculty of Civil Engineering, Universiti Teknologi Malaysia, Skudai, Johor (Malaysia)

    2015-05-15

    Behaviour between two materials in composite beam is assumed partially interact when longitudinal slip at its interfacial surfaces is considered. Commonly analysed by the mesh-based formulation, this study used meshless formulation known as Element Free Galerkin (EFG) method in the beam partial interaction analysis, numerically. As meshless formulation implies that the problem domain is discretised only by nodes, the EFG method is based on Moving Least Square (MLS) approach for shape functions formulation with its weak form is developed using variational method. The essential boundary conditions are enforced by Langrange multipliers. The proposed EFG formulation gives comparable results, after been verified by analytical solution, thus signify its application in partial interaction problems. Based on numerical test results, the Cubic Spline and Quartic Spline weight functions yield better accuracy for the EFG formulation, compares to other proposed weight functions.

  4. Finite element analysis of composite concrete-timber beams

    Directory of Open Access Journals (Sweden)

    N. C. S. FORTI

    Full Text Available AbstractIn the search for sustainable construction, timber construction is gaining in popularity around the world. Sustainably harvested wood stores carbon dioxide, while reforestation absorbs yet more CO2. One technique involves the combination of a concrete slab and a timber beam, where the two materials are assembled by the use of flexible connectors. Composite structures provide reduced costs, environmental benefits, a better acoustic performance, when compared to timber structures, and maintain structural safety. Composite structures combine materials with different mechanical properties. Their mechanical performance depends on the efficiency of the connection, which is designed to transmit shear longitudinal forces between the two materials and to prevent vertical detachment. This study contributes with the implementation of a finite element formulation for stress and displacement determination of composite concrete-timber beams. The deduced stiffness matrix and load vector are presented along to numerical examples. Numerical examples are compared to the analytical equations available in Eurocode 5 and to experimental data found in the literature.

  5. Radiation sources EB and UV curing machines

    International Nuclear Information System (INIS)

    Takashi Sasaki

    1993-01-01

    This paper describes electron beam processors and related technologies for curing applications to facilitate those industrial personals who are trying to understand and evaluate the applicability and benefits of radiation curing to their products. 4 tabs., 10 figs

  6. Radiation sources EB and UV curing machines

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Takashi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1994-12-31

    This paper describes electron beam processors and related technologies for curing applications to facilitate those industrial personals who are trying to understand and evaluate the applicability and benefits of radiation curing to their products. 4 tabs., 10 figs.

  7. Application of electron and Bremsstrahlung beams for composite materials processing

    International Nuclear Information System (INIS)

    Zalyubovsky, I.I.; Avilov, A.M.; Popov, G.F.; Rudychev, V.G.

    1998-01-01

    In Kharkiv University the radiation process of obtaining composite polymer materials, CPM, with high strength properties and corrosion resistance was studied. CPM are manufactured by vacuum impregnating capillary-porous materials with synthetic monomers and oligomers or by molding granular waste and resins which are further treated by relativistic electron or Bremsstrahlung beam. Such radiation treatment yields new CPM in which capillary-porous structure acting as reinforcement is filled with polymer. The results of the applied research with industrial electron accelerator in the field of thick CPM formation are presented

  8. Light energy transmission and Vickers hardness ratio of bulk-fill resin based composites at different thicknesses cured by a dual-wave or a single-wave light curing unit.

    Science.gov (United States)

    Santini, Ario; Naaman, Reem Khalil; Aldossary, Mohammed Saeed

    2017-04-01

    To quantify light energy transmission through two bulk-fill resin-based composites and to measure the top to bottom surface Vickers hardness ratio (VHratio) of samples of various incremental thicknesses, using either a single-wave or dual-wave light curing unit (LCU). Tetric EvoCeram Bulk Fill (TECBF) and SonicFill (SF) were studied. Using MARC-RC, the irradiance delivered to the top surface of the samples 2, 3, 4 and 5 mm thick (n= 5 for each thickness) was adjusted to 800 mW/cm2 for 20 seconds (16 J/cm2) using either a single-wave, Bluephase or a dual-wave, Bluephase G2 LCUs. Light energy transmission through to the bottom surface of the specimens was measured at real time using MARC-RC. The Vickers hardness (VH) was determined using Vickers micro hardness tester and the VHratio was calculated. Data were analyzed using a general linear model in Minitab 16; α= 0.05. TECBF was more translucent than SF (Pwave Bluephase G2). SF showed significantly higher VH ratio than TECBF at all different thickness levels (P 0.05). TECBF showed significantly greater VH ratio when cured with the single-wave Bluephase than when using the dual-wave Bluephase G2 (Penergy through to the bottom surface and the VHratio are material dependent. Although TECBF is more translucent than SF, it showed lower VHratio compared to SF when cured with dual-wave Bluephase G2.

  9. Mechanical Characterization of In and Out-of-Autoclave Cured Composite Panels for Large Launch Vehicles

    Science.gov (United States)

    Kellas, Sotiris; Lerch, Bradley A.; Wilmoth, Nathan

    2012-01-01

    Two manufacturing demonstration panels (1/16th-arc-segments of 10 m diameter cylinder) were fabricated under the composites part of the Lightweight Space Structures and Materials program. Both panels were of sandwich construction with aluminum core and 8-ply quasi-isotropic graphite/epoxy facesheets. One of the panels was constructed with in-autoclave curable unidirectional prepreg (IM7/977-3) and the second with out-of-autoclave unidirectional prepreg (T40-800B/5320-1). Following NDE inspection, each panel was divided into a number of small specimens for material property characterization and a large (0.914 m wide by 1.524 m long) panel for a buckling study. Results from the small specimen tests were used to (a) assess the fabrication quality of each 1/16th arc segment panel and (b) to develop and/or verify basic material property inputs to Finite Element analysis models. The mechanical performance of the two material systems is assessed at the coupon level by comparing average measured properties such as flatwise tension, edgewise compression, and facesheet tension. The buckling response of the 0.914 m wide by 1.524 m long panel provided a comparison between the in- and out-of autoclave systems at a larger scale.

  10. Color stability and degree of cure of direct composite restoratives after accelerated aging.

    Science.gov (United States)

    Sarafianou, Aspasia; Iosifidou, Soultana; Papadopoulos, Triantafillos; Eliades, George

    2007-01-01

    This study evaluated the color changes and amount of remaining C = C bonds (%RDB) in three dental composites after hydrothermal- and photoaging. The materials tested were Estelite sigma, Filtek Supreme and Tetric Ceram. Specimens were fabricated from each material and subjected to L* a* b* colorimetry and FTIR spectroscopy before and after aging. Statistical evaluation of the deltaL,* deltaa,* deltab,* deltaE and %deltaRDB data was performed by one-way ANOVA and Tukey's test. The %RDB data before and after aging were statistically analyzed using two-way ANOVA and Student-Newman-Keuls test. In all cases an alpha = 0.05 significance level was used. No statistically significant differences were found in deltaL*, deltaa*, deltaE and %deltaRDB among the materials tested. Tetric Ceram demonstrated a significant difference in deltab*. All the materials showed visually perceptible (deltaE >1) but clinically acceptable values (deltaE statistically significant differences in %RDB were noticed before and after aging (p statistically significantly different among all the groups tested. No correlation was found between deltaE and %deltaRDB.

  11. UV-Assisted 3D Printing of Glass and Carbon Fiber-Reinforced Dual-Cure Polymer Composites.

    Science.gov (United States)

    Invernizzi, Marta; Natale, Gabriele; Levi, Marinella; Turri, Stefano; Griffini, Gianmarco

    2016-07-16

    Glass (GFR) and carbon fiber-reinforced (CFR) dual-cure polymer composites fabricated by UV-assisted three-dimensional (UV-3D) printing are presented. The resin material combines an acrylic-based photocurable resin with a low temperature (140 °C) thermally-curable resin system based on bisphenol A diglycidyl ether as base component, an aliphatic anhydride (hexahydro-4-methylphthalic anhydride) as hardener and (2,4,6,-tris(dimethylaminomethyl)phenol) as catalyst. A thorough rheological characterization of these formulations allowed us to define their 3D printability window. UV-3D printed macrostructures were successfully demonstrated, giving a clear indication of their potential use in real-life structural applications. Differential scanning calorimetry and dynamic mechanical analysis highlighted the good thermal stability and mechanical properties of the printed parts. In addition, uniaxial tensile tests were used to assess the fiber reinforcing effect on the UV-3D printed objects. Finally, an initial study was conducted on the use of a sizing treatment on carbon fibers to improve the fiber/matrix interfacial adhesion, giving preliminary indications on the potential of this approach to improve the mechanical properties of the 3D printed CFR components.

  12. UV-Assisted 3D Printing of Glass and Carbon Fiber-Reinforced Dual-Cure Polymer Composites

    Directory of Open Access Journals (Sweden)

    Marta Invernizzi

    2016-07-01

    Full Text Available Glass (GFR and carbon fiber-reinforced (CFR dual-cure polymer composites fabricated by UV-assisted three-dimensional (UV-3D printing are presented. The resin material combines an acrylic-based photocurable resin with a low temperature (140 °C thermally-curable resin system based on bisphenol A diglycidyl ether as base component, an aliphatic anhydride (hexahydro-4-methylphthalic anhydride as hardener and (2,4,6,-tris(dimethylaminomethylphenol as catalyst. A thorough rheological characterization of these formulations allowed us to define their 3D printability window. UV-3D printed macrostructures were successfully demonstrated, giving a clear indication of their potential use in real-life structural applications. Differential scanning calorimetry and dynamic mechanical analysis highlighted the good thermal stability and mechanical properties of the printed parts. In addition, uniaxial tensile tests were used to assess the fiber reinforcing effect on the UV-3D printed objects. Finally, an initial study was conducted on the use of a sizing treatment on carbon fibers to improve the fiber/matrix interfacial adhesion, giving preliminary indications on the potential of this approach to improve the mechanical properties of the 3D printed CFR components.

  13. Synthesis and characterizations of high permittivity ultraviolet cured soft elastomeric networks and composites applicable as dielectric electroactive polymer

    DEFF Research Database (Denmark)

    Goswami, Kaustav

    (propylene oxide) (PPO) were prepared which showed marked improvements in properties compared to the acrylic elastomers. But difficulties in curing by industrial processes and handling of these elastomers posed as limitations. So the focus was on optimizing UV induced thiol-ene reactions for curing...

  14. The potential of dielectric analysis as an on-line cure monitoring technique in the manufacture of advanced fibre reinforced composites

    International Nuclear Information System (INIS)

    McIlhagger, A.T.

    2002-02-01

    Composite manufacturing processes such as RTM, are being developed in the aerospace industry in order to promote and reduce the cost of advanced fibre reinforced composites. The aerospace industry has identified the need for a cure monitoring system to be utilised in this production, to improve the efficiency and reliability of processing. The system must be able to determine through-thickness properties of the composite, on-line and without affecting the integrity of the finished component. Literature has shown that a number of techniques are available but these do not address all of the requirements of industry. The most important process parameters in RTM are the resin flow, point of minimum viscosity, gelation and subsequent completion of cure. These 'key cure parameters' are often difficult to control accurately in the manufacturing environment. Although dielectric analysis has been around for many years, literature identified an urgent requirement for research on the interpretation of dielectric sensor data relating to these main process parameters. A dielectric laboratory instrument, operated in the parallel plate sensor configuration was utilised to simulate a standard RTM cure cycle. The important transitions in the resin, namely minimum viscosity, gelation, vitrification and completion of cure, were identified. The parallel plate dielectric technique was applied to composites containing conductive and non-conductive reinforcement fibres. The appropriate dielectric signals and frequency were determined based on the sensor configuration, insulating layer and resin/fabric type. Correlations have been demonstrated between dielectric results and other established thermal (DSC and. DMA) and mechanical test techniques (tensile, flexural and interlaminar shear). Test methods were designed and investigated to provide information to compare with dielectric data. The parallel plate configuration was used to investigate the effect of composite thickness variation on

  15. Industrial application of radiation curing

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Takashi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1994-12-31

    The contents are advantages of radiation processes - a solvent-free system, less energy consumative, higher production rate, processability at ambient temperature; electron beams vs. ultraviolet curing; applications -broad spectrum of markets use radiation curable materials.

  16. Industrial application of radiation curing

    International Nuclear Information System (INIS)

    Takashi Sasaki

    1993-01-01

    The contents are advantages of radiation processes - a solvent-free system, less energy consumative, higher production rate, processability at ambient temperature; electron beams vs. ultraviolet curing; applications -broad spectrum of markets use radiation curable materials

  17. Real-time Cure Monitoring of Composites Using a Guided wave-based System with High Temperature Piezoelectric Transducers, Fiber Bragg Gratings, and Phase-shifted Fiber Bragg Gratings

    Science.gov (United States)

    Hudson, Tyler Blake

    An in-process, in-situ cure monitoring technique utilizing a guided wave-based concept for carbon fiber reinforced polymer (CFRP) composites was investigated. Two automated cure monitoring systems using guided-wave ultrasonics were developed for characterizing the state of the cure. In the first system, surface mounted high-temperature piezoelectric transducer arrays were employed for actuation and sensing. The second system motivated by the success of the first system includes a single piezoelectric disc, bonded onto the surface of the composite for excitation; fiber Bragg gratings (FBGs) and/or phase-shifted fiber Bragg gratings (PSFBGs) were embedded in the composite for distributed cure sensing. Composite material properties (viscosity and degree of cure) evolved during cure of the panels fabricated from HexcelRTM IM7/8552 prepreg correlated well to the amplitude, time of arrival, and group velocity of the guided wave-based measurements during the cure cycle. In addition, key phase transitions (gelation and vitrification) were clearly identified from the experimental data during the same cure cycle. The material properties and phase transitions were validated using cure process modeling software (e.g., RAVENRTM). The high-temperature piezoelectric transducer array system demonstrated the feasibility of a guided wave-based, in-process, cure monitoring and provided the framework for defect detection during cure. Ultimately, this system could provide a traceable data stream for non-compliance investigations during serial production and perform closed-loop process control to maximize composite panel quality and consistency. In addition, this system could be deployed as a "smart" caul/tool plate to existing production lines without changing the design of the aircraft/structure. With the second system, strain in low frequency (quasi-static) and the guided wavebased signals in several hundred kilohertz range were measured almost simultaneously using the same FBG or PS

  18. Prediction on flexural strength of encased composite beam with cold-formed steel section

    Science.gov (United States)

    Khadavi, Tahir, M. M.

    2017-11-01

    A flexural strength of composite beam designed as boxed shaped section comprised of lipped C-channel of cold-formed steel (CFS) facing each other with reinforcement bars is proposed in this paper. The boxed shaped is kept restrained in position by a profiled metal decking installed on top of the beam to form a slab system. This profiled decking slab is cast by using self-compacting concrete where the concrete is in compression when load is applied to the beam. Reinforcement bars are used as shear connector between slab and CFS as beam. A numerical analysis method proposed by EC4 is used to predict the flexural strength of the proposed composite beam. It was assumed that elasto-plastic behaviour is developed in the cross -sectional of the proposed beam. The calculated predicted flexural strength of the proposed beam shows reasonable flexural strength for cold-formed composite beam.

  19. The Effect of Bulk Depth and Irradiation Time on the Surface Hardness and Degree of Cure of Bulk-Fill Composites

    Directory of Open Access Journals (Sweden)

    Farahat F

    2016-09-01

    Full Text Available Statement of Problem: For many years, application of the composite restoration with a thickness less than 2 mm for achieving the minimum polymerization contraction and stress has been accepted as a principle. But through the recent development in dental material a group of resin based composites (RBCs called Bulk Fill is introduced whose producers claim the possibility of achieving a good restoration in bulks with depths of 4 or even 5 mm. Objectives: To evaluate the effect of irradiation times and bulk depths on the degree of cure (DC of a bulk fill composite and compare it with the universal type. Materials and Methods: This study was conducted on two groups of dental RBCs including Tetric N Ceram Bulk Fill and Tetric N Ceram Universal. The composite samples were prepared in Teflon moulds with a diameter of 5 mm and height of 2, 4 and 6 mm. Then, half of the samples in each depth were cured from the upper side of the mould for 20s by LED light curing unit. The irradiation time for other specimens was 40s. After 24 hours of storage in distilled water, the microhardness of the top and bottom of the samples was measured using a Future Tech (Japan- Model FM 700 Vickers hardness testing machine. Data were analyzed statistically using the one and multi way ANOVAand Tukey’s test (p = 0.050. Results: The DC of Tetric N Ceram Bulk Fill in defined irradiation time and bulk depth was significantly more than the universal type (p < 0.001. Also, the DC of both composites studied was significantly (p < 0.001 reduced by increasing the bulk depths. Increasing the curing time from 20 to 40 seconds had a marginally significant effect (p ≤ 0.040 on the DC of both bulk fill and universal studied RBC samples. Conclusions: The DC of the investigated bulk fill composite was better than the universal type in all the irradiation times and bulk depths. The studied universal and bulk fill RBCs had an appropriate DC at the 2 and 4 mm bulk depths respectively and

  20. Study on fabrication methods of composite structures (1st. report); Joule effect curing of CFRP composite structures and its application to bonding and repair. Fukugo zai kozo no seikei kako ho ni kansuru kenkyu (Dai 1po); CFRP kozo no Joule koka wo riyo shita cure ho to setsugoter dot hoshu e no oyo ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Moriya, K. (The National Defense Academy, Kanagawa (Japan))

    1990-07-05

    A method for curing CFRP composite structures by using Joule effect is presented. Due to the presence of fiber to fiber contact, CFRP composites and their prepregs exhibit electrical conductivity in the direction transverse to fibers as well as in the fiber direction, and they can be considered as electrically homogeneous on a gross scale. Therefore, passing an electric current through a CFRP prepreg, it is self-heated due to the Joule effect. Feedback current control maintains the prepreg temperature at a desired level and makes the prepreg be cured by a specified cure cycle. Experimental verifiactions have been carried out to demonstrate the feasibility of the present technique. The applications to the bonding of CFRP components and to the patch repairs of effective CFRP structure are also described. 12 refs., 12 figs.

  1. Properties of radiation cured coatings

    International Nuclear Information System (INIS)

    Larson, E.G.; Spencer, D.S.; Boettcher, T.E.; Melbauer, M.A.; Skarjune, R.P.

    1987-01-01

    Coatings were prepared from acrylate or methacrylate functionalized resins to study the effect of end group functionality on the physical properties of u.v. and electron beam cured coatings. Cure response was measured by solid state NMR and gel extraction, as expected, methacrylate resins cured much slower. Thermal Gravimetric Analysis (TGA) revealed acrylate coatings have greater thermal stability. Properties such as tensile strength and hardness showed little effect of end group functionality or curing method. The O 2 and H 2 O permeabilities of the coating were correlated with the processing conditions. (author)

  2. Process for producing a coating composition. [electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, T; Harada, H; Kobayashi, S; Nakamoto, H; Sunano, K

    1968-07-19

    An easily hardenable acrylic coating composition is produced by irradiation with low energy electron beams to economize the industrial application of the composition. A polymer with molecular weights in the 5,000 to 500,000 range is composed of 1 to 40% by weight of a vinyl monomer containing a glycidyl radical, 30 to 99% of a methacrylic monomer and 0 to 69% of other copolymerizable vinyl monomers. This polymer dissolves in a monomer containing at least 30% of an acrylic monomer and 70% of other vinyl monomers. The reaction takes place between 0.1 to 1.0 mole of vinyl monomer containing a carboxyl radical and one mole of glycidyl radical in the solution. In an embodiment, 17.5% by weight of glycidyl methacrylate and 82.5% of alkyl acrylate are polymerized in suspension in the presence of a catalyst to form a bead like polymer with molecular weights in the 5,000 to 500,000 range. After 120 parts of the bead like polymer are dissolved in 180 parts of the acrylic monomer in the presence of a polymerization inhibitor by heating, 22 parts of ..cap alpha.., ..beta..- unsaturated monocarboxylic acid are added to the solution to react with the glycidyl radical, whereby a non-solvent type coating material containing the polymer having a vinyl radical side chain is produced. In the place of the catalyst, electron beams can be used at an energy level of 0.1 to 20 MeV. The dose rate may be in the range of 0.1 to 2.0 Mrad/sec.

  3. Influence of Curing Age and Mix Composition on Compressive Strength of Volcanic Ash Blended Cement Laterized Concrete

    Directory of Open Access Journals (Sweden)

    Babafemi A.J.

    2012-01-01

    Full Text Available This study investigates the influence of curing age and mix proportions on the compressive strength of volcanic ash (VA blended cement laterized concrete. A total of 288 cubes of 100mm dimensions were cast and cured in water for 3, 7, 28, 56, 90 and 120 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively while a control mix of 28-day target strength of 25N/mm2 (using British Method was adopted. The results show that the compressive strength of the VA-blended cement laterized concrete increased with the increase in curing age but decreased as the VA and laterite (LAT contents increased. The optimum replacement level was 20%LAT/20%VA. At this level the compressive strength increased with curing age at a decreasing rate beyond 28 days. The target compressive strength of 25N/mm2 was achieved for this mixture at 90 days of curing. VA content and curing age was noted to have significant effect (α ≤ 0.5 on the compressive strength of the VA-blended cement laterized concrete.

  4. Static and Vibrational Analysis of Partially Composite Beams Using the Weak-Form Quadrature Element Method

    Directory of Open Access Journals (Sweden)

    Zhiqiang Shen

    2012-01-01

    Full Text Available Deformation of partially composite beams under distributed loading and free vibrations of partially composite beams under various boundary conditions are examined in this paper. The weak-form quadrature element method, which is characterized by direct evaluation of the integrals involved in the variational description of a problem, is used. One quadrature element is normally sufficient for a partially composite beam regardless of the magnitude of the shear connection stiffness. The number of integration points in a quadrature element is adjustable in accordance with convergence requirement. Results are compared with those of various finite element formulations. It is shown that the weak form quadrature element solution for partially composite beams is free of slip locking, and high computational accuracy is achieved with smaller number of degrees of freedom. Besides, it is found that longitudinal inertia of motion cannot be simply neglected in assessment of dynamic behavior of partially composite beams.

  5. Development situation of radiation curing materials

    International Nuclear Information System (INIS)

    He Songhua; Luo Junyi; Liu Zhen

    2010-01-01

    Due to fitting the '4E' principle, radiation curing technology, known as green technology, have shown its own superiority in many applications. It has been rapid developed in China and abroad in recent years, especially ultraviolet/electron beam (UV/EB) radiation curing technology. In order to let the researchers have a general understanding on the radiation curing materials and their development, in this paper a briefly introducing on the related radiation sources, chemical systems, curing mechanism, and the application, the common and difference of ultraviolet curing and electron beam curing has been made. A brief account of development of radiation-curable material in China and the outlook of the development of materials can be found in this paper. At last, we have proposed that the development of radiation curing technology will promote the development of the radiation curing material and benefit in the humanity. (authors)

  6. Structural aspects of cold-formed steel section designed as U-shape composite beam

    Science.gov (United States)

    Saggaff, Anis; Tahir, Mahmood Md.; Azimi, Mohammadamin; Alhajri, T. M.

    2017-11-01

    Composite beam construction usually associated with old-style Hot-Rolled Steel Section (HRSS) has proven to act much better in compare with Cold-Formed Steel Section (CFSS) sections due to thicker section. Due, it's getting popular to replace HRSS with CFSS in some aspects as a composite beam. The advantages such as lightweight, cost effective and easy to install have contributed to the apply CFSS as a preferred construction material for composite beam. There is a few technical data available regarding the application of the usage of CFSS as a composite system, despite the potentials use for residential and light-weight industrial constructions. This paper presents an experimental tests results which have been conducted using CFSS as composite beam. Composite action of CFSS arranged as double beam with Self-Compacting Concrete (SCC) slab are integrated together with bolted shear connectors were used. A full-scale test comprised of 3 proposed composite beam specimens with bolted shear connector spaced at 300 mm interval of grade 8.8 was using single nut with washer on flange of CFS, cast to the slab and loaded until failed. The test show that the bolted shear connector yielded better capacity of ultimate strength and ultimate moment for the proposed composite beam. It can be concluded that, bolted shear connectors of 16 mm in diameter performed better than the other diameter size of bolted shear connectors.

  7. Hard facts for radiation curing of elastomers

    International Nuclear Information System (INIS)

    Lyall, D.J.

    1984-01-01

    The subject is covered under the headings: introduction; outline of chemistry (differences between conventional and radiation curing); compounding; green strength; response of rubbers to electron beam treatment; electron beam cured applications:(a) wire and cable applications;(b) rubber tyre components;(c) heat shrinkable materials;(d) roofing materials. (U.K.)

  8. Surface composition of biomedical components by ion beam analysis

    International Nuclear Information System (INIS)

    Kenny, M.J.; Wielunski, L.S.; Baxter, G.R.

    1991-01-01

    Materials used for replacement body parts must satisfy a number of requirements such as biocompatibility and mechanical ability to handle the task with regard to strength, wear and durability. When using a CVD coated carbon fibre reinforced carbon ball, the surface must be ion implanted with uniform dose of nitrogen ions in order to make it wear resistant. The mechanism by which the wear resistance is improved is one of radiation damage and the required dose of about 10 16 cm -2 can have a tolerance of about 20%. To implant a spherical surface requires manipulation of the sample within the beam and control system (either computer or manually operated) to enable uniform dose all the way from polar to equatorial regions on the surface. A manipulator has been designed and built for this purpose. In order to establish whether the dose is uniform, nuclear reaction analysis using the reaction 14 N(d,α) 12 C is an ideal method of profiling. By taking measurements at a number of points on the surface, the uniformity of nitrogen dose can be ascertained. It is concluded that both Rutherford Backscattering and Nuclear Reaction Analysis can be used for rapid analysis of surface composition of carbon based materials used for replacement body components. 2 refs., 2 figs

  9. Behaviour of steel-concrete composite beams using bolts as shear connectors

    Science.gov (United States)

    Tran, Minh-Tung; Nguyen Van Do, Vuong; Nguyen, Tuan-Anh

    2018-04-01

    The paper presents an experimental program on the application of bolts as shear connectors for steel-composite beams. Four steel- concrete composite beams and a reference steel beam were made and tested. The aim of the testing program is to examine which forms of the steel bolts can be used effectively for steel-composite beams. The four types of the bolts include: Type 1 the bolt with the nut at the end; Type 2 the bolt bending at 900 hook; Type 3 the bolt without the nut at the end and Type 4 the bolt with the nut at the end but connected with the steel beam by hand welding in other to be connected with the steel beam by bolt connection as in the first three types. The test results showed that beside the traditional shear connectors like shear studs, angle type, channel type, bolts can be used effectively as the shear connectors in steel-composite beams and the application of bolts in Types 1 and 2 in the composite beams gave the better performance for the tested beam.

  10. Strengthening Performance of PALF-Epoxy Composite Plate on Reinforced Concrete Beams

    Science.gov (United States)

    Chin, Siew C.; Tong, Foo S.; Doh, Shu I.; Gimbun, Jolius; Ong, Huey R.; Serigar, Januar P.

    2018-03-01

    This paper presents the effective strengthening potential of pineapple leaves fiber (PALF)-epoxy composite plate on reinforced concrete (RC) beam. At first the PALF is treated with alkali (NaOH) and its morphology is observed via scanning electron microscope (SEM). The composite plates made of PALF and epoxy with fiber loading ranging from 0.1 to 0.4 v/v was tested for its flexural behaviour. The composite was then used for external RC beam strengthening. The structural properties of RC beams were evaluated and all the beams were tested under four-point bending. It was found that the flexural strength increased as the fiber volume ratio increases. The maximum flexural strength (301.94 MPa) was obtained at the fiber volume ratio of 40%. The beam strengthened with PALF-epoxy composite plate has a 7% higher beam capacity compared to the control beam. Cracks formed at the edge of the plate of PALF-strengthened beams resulted in diagonal cracking. Result from this work shows that the PALF-epoxy composite plate has the potential to be used as external strengthening material for RC beam.

  11. Relationship of Cure Temperature to Mechanical, Physical, and Dielectric Performance of PDMS Glass Composite for Electric Motor Insulation

    Science.gov (United States)

    Miller, Sandi G.; Becker, Kathleen; Williams, Tiffany S.; Scheiman, Daniel A.; McCorkle, Linda S.; Heimann, Paula J.; Ring, Andrew; Woodworth, Andrew

    2017-01-01

    Achieving NASAs aggressive fuel burn and emission reduction for N-plus-3 aircraft will require hybrid electric propulsion system in which electric motors driven by either power generated from turbine or energy storage system will power the fan for propulsion. Motors designed for hybrid electric aircraft are expected to operate at medium to high voltages over long durations in a high altitude service environment. Such conditions have driven research toward the development of wire insulation with improved mechanical strength, thermal stability and increased breakdown voltage. The silicone class of materials has been considered for electric wire insulation due to its inherent thermal stability, dielectric strength and mechanical integrity. This paper evaluates the dependence of these properties on the cure conditions of a polydimethyl-siloxane (PDMS) elastomer; where both cure temperature and base-to-catalyst ratio were varied. The PDMS elastomer was evaluated as a bulk material and an impregnation matrix within a lightweight glass veil support. The E-glass support was selected for mechanical stiffness and dielectric strength. This work has shown a correlation between cure conditions and material physical properties. Tensile strength increased with cure temperature whereas breakdown voltage tended to be independent of process variations. The results will be used to direct material formulation based on specific insulation requirements.

  12. Curing time effect on the fraction of 137Cs from cement- ion exchange resins-bentonite clay composition

    International Nuclear Information System (INIS)

    Plecas, I.; Dimovic, S.

    2007-01-01

    Curing conditions and time are critically important in leach studies since the extent of hydratation of the cement materials determines how much hydratation product develops and whether it is available to block the pore network, thereby reducing leaching.[1,2]. To assess the safety of disposal of radioactive waste material in cement, curing conditions and time of leaching radionuclide 137 Cs has been studied in this paper. Leaching tests in cement-ion exchange resins-bentonite matrix, were carried out in accordance with a method recommended by IAEA. Curing conditions and curing time prior to commencing the leaching test are critically important in leach studies since the extent of hydration of the cement materials determines how much hydration product develop and whether it is available to block the pore network, thereby reducing leaching. Incremental leaching rates R n (cm/d) of 137 Cs from cement-ion exchange resins-bentonite matrix after 180 days were measured. The results presented in this paper are examples of results obtained in a 20-year concrete testing project which will influence the design of the engineer trenches system for future central Serbian radioactive waste storing center. (author)

  13. Real-time synchronous measurement of curing characteristics and polymerization stress in bone cements with a cantilever-beam based instrument

    Science.gov (United States)

    Palagummi, Sri Vikram; Landis, Forrest A.; Chiang, Martin Y. M.

    2018-03-01

    An instrumentation capable of simultaneously determining degree of conversion (DC), polymerization stress (PS), and polymerization exotherm (PE) in real time was introduced to self-curing bone cements. This comprises the combination of an in situ high-speed near-infrared spectrometer, a cantilever-beam instrument with compliance-variable feature, and a microprobe thermocouple. Two polymethylmethacrylate-based commercial bone cements, containing essentially the same raw materials but differ in their viscosity for orthopedic applications, were used to demonstrate the applicability of the instrumentation. The results show that for both the cements studied the final DC was marginally different, the final PS was different at the low compliance, the peak of the PE was similar, and their polymerization rates were significantly different. Systematic variation of instrumental compliance for testing reveals differences in the characteristics of PS profiles of both the cements. This emphasizes the importance of instrumental compliance in obtaining an accurate understanding of PS evaluation. Finally, the key advantage for the simultaneous measurements is that these polymerization properties can be correlated directly, thus providing higher measurement confidence and enables a more in-depth understanding of the network formation process.

  14. Performance of composite I-beams under axial compression and bending load modes

    International Nuclear Information System (INIS)

    Khalid, Y.A.; Ali, F.A.; Sahari, B.B.; Saad, E.M.A.

    2005-01-01

    An experimental and finite-element analyses for glass/epoxy composite I-beams have been carried out. Four, six, eight and 10 layers of woven fabric glass/epoxy composite I-beams were fabricated by a hand lay-up (molding) process. Quasi-static axial crushing and bending loading modes were used for this investigation. The load-displacement response was obtained and the energy absorption values were calculated for all the composite I-beams. Three tests were done for each composite I-beams type and each loading case for the results conformation. The second part of this study includes the elastic behavior of composite I-beams of the same dimensions and materials using finite-element analysis. The woven fabric glass/epoxy composite I-beams mechanical properties have been obtained from tensile tests. Results from this investigation show that the load required and the specific energy absorption for composite I-beams under axial compression load were higher than those for three and four point bending. On the other hand, the loads required for composite I-beams under four point bending were higher than those for three point bending, while the specific energy absorption for composite I-beams under three point bending were higher than those for four point bending. The first crushing loads difference between the experimental and finite-element results fell in the 3.6-10.92% range for axial compression tests, while fell in the 1.44-12.99% and 4.94-22.0% range for three and four point bending, respectively

  15. Effect of high intensity vs. soft-start halogen irradiation on light-cured resin-based composites. Part I. Temperature rise and polymerization shrinkage.

    Science.gov (United States)

    Hofmann, Norbert; Markert, Tanja; Hugo, Burkard; Klaiber, Bernd

    2003-12-01

    To determine polymerization shrinkage kinetics and temperature rise of light-cured resin-based composites after high intensity vs. soft-start quartz tungsten halogen irradiation. Shrinkage kinetics was evaluated using the "deflecting disk technique", modified for simultaneous measurement of temperature within the resin-based composite using a thermocouple. Additional irradiations after 60 and 65 minutes allowed the determination of temperature rises caused by radiation or by reaction heat. Four hybrids (Filtek Z250, Herculite, Solitaire 2, Tetric Ceram), an inhomogeneously filled hybrid (InTen-S) and a microfill (Filtek A110, formerly Silux Plus) were cured using the quartz tungsten halogen units Astralis 10 and Optilux 501 in the high intensity (A10 HiPo: 10 seconds at 1300 mW/cm2; OL Boost: 10 seconds at 1140 mW/cm2) or soft-start modes (A10 Pulse: increase to 700 mW/cm2 within 10 seconds, three periods of 2 seconds at 1300 mW/cm2 alternating with two periods of 2 seconds at 700 mW/cm2; OL Ramp: exponential increase within 10 seconds, followed by 10 seconds at 1140 mW/cm2). The soft-start protocols produced less contraction, and polymerization shrinkage started later and progressed slower (or: more slowly), compared to high intensity irradiation [correction]. The lowest shrinkage was observed for InTen-S, followed by Filtek Z250 and A110, whereas Solitaire 2, Herculite and Tetric Ceram scored highest for this parameter. Temperature rise was caused more or less equally by radiation and by reaction heat and reached values of up to 28.9 degrees C relative to a baseline of 37 degrees C. For some combinations of curing modes and resin-based composites, less heat was generated by the soft-start protocols and by Optilux 501.

  16. An experimental approach to free vibration analysis of smart composite beam

    Science.gov (United States)

    Yashavantha Kumar, G. A.; Sathish Kumar, K. M.

    2018-02-01

    Experimental vibration analysis is a main concern of this study. In designing any structural component the important parameter that has to be considered is vibration. The present work involves the experimental investigation of free vibration analysis of a smart beam. Smart beam consists of glass/epoxy composite as a main substrate and two PZT patches. The PZT patches are glued above and below the main beam. By experimentation the natural frequencies and mode shapes are obtained for both with and without PZT patches of a beam. Finally through experimentation the response of the smart beam is recorded.

  17. Vibration Properties of a Steel-PMMA Composite Beam

    Directory of Open Access Journals (Sweden)

    Yuyang He

    2015-01-01

    Full Text Available A steel-polymethyl methacrylate (steel-PMMA beam was fabricated to investigate the vibration properties of a one-dimensional phononic crystal structure. The experimental system included an excitation system, a signal acquisition system, and a data analysis and processing system. When an excitation signal was exerted on one end of the beam, the signals of six response points were collected with acceleration sensors. Subsequent signal analysis showed that the beam was attenuated in certain frequency ranges. The lumped mass method was then used to calculate the bandgap of the phononic crystal beam to analyze the vibration properties of a beam made of two different materials. The finite element method was also employed to simulate the vibration of the phononic crystal beam, and the simulation results were consistent with theoretical calculations. The existence of the bandgap was confirmed experimentally and theoretically, which allows for the potential applications of phononic crystals, including wave guiding and filtering, in integrated structures.

  18. Experimental testing of a self-sensing FRP-concrete composite beam using FBG sensors

    Science.gov (United States)

    Wang, Yanlei; Hao, Qingduo; Ou, Jinping

    2009-03-01

    A new kind of self-sensing fiber reinforced polymer (FRP)-concrete composite beam, which consists of a FRP box beam combined with a thin layer of concrete in the compression zone, was developed by using two embedded FBG sensors in the top and bottom flanges of FRP box beam at mid-span section along longitudinal direction, respectively. The flexural behavior of the proposed self-sensing FRP-concrete composite beam was experimentally studied in four-point bending. The longitudinal strains of the composite beam were recorded using the embedded FBG sensors as well as the surfacebonded electric resistance strain gauges. Test results indicate that the FBG sensors can faithfully record the longitudinal strain of the composite beam in tension at bottom flange of the FRP box beam or in compression at top flange over the entire load range, as compared with the surface-bonded strain gauges. The proposed self-sensing FRP-concrete composite beam can monitor its longitudinal strains in serviceability limit state as well as in strength limit state, and will has wide applications for long-term monitoring in civil engineering.

  19. Vibration Properties of a Steel-PMMA Composite Beam

    OpenAIRE

    He, Yuyang; Jin, Xiaoxiong

    2015-01-01

    A steel-polymethyl methacrylate (steel-PMMA) beam was fabricated to investigate the vibration properties of a one-dimensional phononic crystal structure. The experimental system included an excitation system, a signal acquisition system, and a data analysis and processing system. When an excitation signal was exerted on one end of the beam, the signals of six response points were collected with acceleration sensors. Subsequent signal analysis showed that the beam was attenuated in certain fre...

  20. The Effect of Slamming Impact on Out-of-Autoclave Cured Prepregs of GFRP Composite Panels for Hulls

    OpenAIRE

    Suárez, J.C.; Townsend, P.; Sanz, E.; Ulzurrum, I. Diez de; Pinilla, P.

    2016-01-01

    This paper proposes a methodology that employs an experimental apparatus that reproduces, in pre-impregnated and cured out-of-autoclave Glass Fiber Reinforced Polymer (GFRP) panels, the phenomenon of slamming or impact on the bottom of a high-speed boat during planing. The pressure limits in the simulation are defined by employing a finite element model (FEM) that evaluates the forces applied by the cam that hits the panels in the apparatus via microdeformations obtained in the simulation. Th...

  1. The irradiation curing of coatings

    International Nuclear Information System (INIS)

    Autio, T.

    1974-01-01

    The electron beam irradiation curing of coatings has been technically feasible for over a decade. A brief description of the process is presented. The progress in this field has been astonishingly slow in comparison with the use of UV lamps as radiation source. The primary reason for this has been the great advantage in terms of capital cost of the UV curing lines and their ready adaptability to low or high production rates. A literature survey is given concerning basic and applied research in the electron curing area, patents, economics and existing installations around the world. (author)

  2. Cracking and Strain Analysis of Beams Reinforced with Composite Bars

    Directory of Open Access Journals (Sweden)

    Edgaras Timinskas

    2012-11-01

    Full Text Available The paper discusses the results of experimental and numerical modelling using two beams reinforced with GFRP bars. One beam was made of plain concrete while the other contained short steel fibres. The influence of steel fibres on deflection and cracking behaviour was studied. A comparative analysis of experimental results has shown that steel fibres significantly reduce deflections and average crack width of the beam. Moreover, an addition of steel fibres to the concrete mix led to a more ductile failure mode of the beam. Numerical analysis employing nonlinear finite element software ATENA has revealed that a good agreement between calculated and experimental results regarding an ordinary concrete GFRP reinforced beam can be obtained.

  3. Phenomenological interpretation of the shear behavior of reinforced Engineered Cementitious Composite beams

    DEFF Research Database (Denmark)

    Paegle, Ieva; Fischer, Gregor

    2016-01-01

    This paper describes an experimental investigation of the shear behavior of beams consisting of steel Reinforced Engineered Cementitious Composites (R/ECC). This study investigates and quantifies the effect of ECC's strain hardening and multiple cracking behavior on the shear capacity of beams...

  4. In-service performance evaluation and monitoring of a hybrid composite beam bridge system : final report.

    Science.gov (United States)

    2017-10-01

    The hybrid composite beam (HCB) technology has been presented as a system for short and medium span beam bridges as an alternative to traditional materials such as concrete and steel. An HCB consists of a concrete tied arch encased in a fiber reinfor...

  5. Vibration Analysis of Cracked Composite Bending-torsion Beams for Damage Diagnosis

    OpenAIRE

    Wang, Kaihong

    2004-01-01

    An analytical model of cracked composite beams vibrating in coupled bending-torsion is developed. The beam is made of fiber-reinforced composite with fiber angles in each ply aligned in the same direction. The crack is assumed open. The local flexibility concept is implemented to model the open crack and the associated compliance matrix is derived. The crack introduces additional boundary conditions at the crack location and these effects in conjunction with those of material properties are i...

  6. Radiation curing

    International Nuclear Information System (INIS)

    Wendrinsky, J.

    1987-04-01

    In the beginning of the seventies the two types of radiation sources applied in industrial processes, electron radiation and UV, had been given rather optimistic forecasts. While UV could succeed in the field of panel and film coating, electron radiation curing seems to gain success in quite new fields of manufacturing. The listing of the suggested applications of radiation curing and a comparison of both advantages and disadvantages of this technology are followed by a number of case studies emphasizing the features of these processes and giving some examplary calculations. The data used for the calculations should provide an easy calculation of individual manufacturing costs if special production parameters, investment or energy costs are employed. (Author)

  7. Post-buckling analysis of composite beams: A simple intuitive ...

    Indian Academy of Sciences (India)

    and lateral displacement functions at any discrete location of the beam. ..... shells under combined axial compression and radial pressure. ... Razakamiadana A and Zidi M 1999 Buckling and post-buckling of concentric cylindrical tubes under.

  8. Fatigue testing of wood-concrete composite beams.

    Science.gov (United States)

    2013-05-01

    Currently, wood-concrete composite structural members are usually applied in building structures. There are a relatively small number (in the low 100s) of known bridge applications involving wood-concrete composites. A problem with using these novel ...

  9. Energy composition of high-energy neutral beams on the COMPASS tokamak

    Czech Academy of Sciences Publication Activity Database

    Mitošinková, Klára; Stöckel, Jan; Varju, Jozef; Weinzettl, Vladimír

    2016-01-01

    Roč. 61, č. 4 (2016), s. 419-423 ISSN 0029-5922. [Summer School of Plasma Diagnostics PhDiaFusion 2015: “Soft X-ray Diagnostics for Fusion Plasma”. Bezmiechowa, 16.06.2015-20.06.2015] R&D Projects: GA MŠk(CZ) LM2011021; GA MŠk(CZ) 8D15001 Institutional support: RVO:61389021 Keywords : tokamak * neutral beam injection (NBI) * Doppler effect * beam composition * beam composition Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.760, year: 2016 http://www.ichtj.waw.pl/nukleonikaa/?p=1256

  10. Deployment Testing of Flexible Composite Hinges in Bi-Material Beams

    Science.gov (United States)

    Sauder, Jonathan F.; Trease, Brian

    2016-01-01

    Composites have excellent properties for strength, thermal stability, and weight. However, they are traditionally highly rigid, and when used in deployable structures require hinges bonded to the composite material, which increases complexity and opportunities for failure. Recent research in composites has found by adding an elastomeric soft matrix, often silicone instead of an epoxy, the composite becomes flexible. This work explores the deployment repeatability of silicone matrix composite hinges which join rigid composite beams. The hinges were found to have sub-millimeter linear deployment repeatability, and sub-degree angular deployment repeatability. Also, an interesting relaxation effect was discovered, as a hinges deployment error would decrease with time.

  11. Estimation of state and material properties during heat-curing molding of composite materials using data assimilation: A numerical study

    Directory of Open Access Journals (Sweden)

    Ryosuke Matsuzaki

    2018-03-01

    Full Text Available Accurate simulations of carbon fiber-reinforced plastic (CFRP molding are vital for the development of high-quality products. However, such simulations are challenging and previous attempts to improve the accuracy of simulations by incorporating the data acquired from mold monitoring have not been completely successful. Therefore, in the present study, we developed a method to accurately predict various CFRP thermoset molding characteristics based on data assimilation, a process that combines theoretical and experimental values. The degree of cure as well as temperature and thermal conductivity distributions during the molding process were estimated using both temperature data and numerical simulations. An initial numerical experiment demonstrated that the internal mold state could be determined solely from the surface temperature values. A subsequent numerical experiment to validate this method showed that estimations based on surface temperatures were highly accurate in the case of degree of cure and internal temperature, although predictions of thermal conductivity were more difficult. Keywords: Engineering, Materials science, Applied mathematics

  12. Determining shear modulus of thin wood composite materials using a cantilever beam vibration method

    Science.gov (United States)

    Cheng Guan; Houjiang Zhang; John F. Hunt; Haicheng Yan

    2016-01-01

    Shear modulus (G) of thin wood composite materials is one of several important indicators that characterizes mechanical properties. However, there is not an easy method to obtain this value. This study presents the use of a newly developed cantilever beam free vibration test apparatus to detect in-plane G of thin wood composite...

  13. Thermal and mechanical properties of palm oil-based polyurethane acrylate/ clay nano composites prepared by in-situ intercalative method and electron beam radiation

    International Nuclear Information System (INIS)

    Salih, A.M.; Mansor Ahmad; Nor Azowa Ibrahim; Rida Tajau; Wan Mohd Zin Wan Yunus

    2013-01-01

    Full-text: Palm oil based-polyurethane acrylate (POBUA)/ clay nano composites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4 ' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5 % wt), and then subjected to polycondensation reaction with MDI. Nano composites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nano clay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up to 37 Angstrom, while the structure morphology of the nano composites was investigated by TEM and SEM. The nano composites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nano composites was significantly increased by incorporation of nano clay into the polymer matrix. DSC results reveal that the T g was shifted to higher values, gradually with increasing the amount of filler in the nano composites. Tensile strength and Young's modulus of the nano composites showed remarkable improvement compared to the neat POBUA. (author)

  14. Modeled and Measured Dynamics of a Composite Beam with Periodically Varying Foam Core

    Science.gov (United States)

    Cabell, Randolph H.; Cano, Roberto J.; Schiller, Noah H.; Roberts Gary D.

    2012-01-01

    The dynamics of a sandwich beam with carbon fiber composite facesheets and foam core with periodic variations in material properties are studied. The purpose of the study is to compare finite element predictions with experimental measurements on fabricated beam specimens. For the study, three beams were fabricated: one with a compliant foam core, a second with a stiffer core, and a third with the two cores alternating down the length of the beam to create a periodic variation in properties. This periodic variation produces a bandgap in the frequency domain where vibrational energy does not readily propagate down the length of the beam. Mode shapes and natural frequencies are compared, as well as frequency responses from point force input to velocity response at the opposite end of the beam.

  15. Novel additives in radiation polymerisation processes. Significance of molecular weight data in their application to grafting, curing and composite formation

    International Nuclear Information System (INIS)

    Garnett, J.L.; Mohajerani, S.; Viengkhou, V.; Loo-Teck NG

    1995-01-01

    The role of additives in accelerating rates of reaction has been investigated in the following related radiation polymerisation processes, i.e simple homopolymerisation, grafting, WPC formation and curing. Additives used include mineral acid, polyfunctional monomers, urea and thermal and photochemical initiators. Molecular weight analysis carried out on the polymers formed in the presence of the additives indicate that both chemical and physical processes are involved in the mechanism of the polymerisation reaction. Chemical processes (free radicals) lead to an enhancement in initial rate of polymerisation whilst the physical parameter involves partitioning of reagents during reaction. Both chemical and physical processes are shown to act in concert to influence both polymer yield and properties

  16. Comparison of silorane and methacrylate-based composites on the polymerization heat generated with different light-curing units and dentin thicknesses.

    Science.gov (United States)

    Guiraldo, Ricardo Danil; Consani, Simonides; Consani, Rafael Leonardo Xediek; Berger, Sandrine Bittencourt; Correr, Américo Bortolazzo; Sinhoreti, Mário Alexandre Coelho; Correr-Sobrinho, Lourenço

    2013-01-01

    This study evaluated the temperature variation in the pulp chamber during photoactivation of two restorative composite resins (Filtek P90 silorane-based composite and Heliomolar methacrylate-based composite) with either a quartz-tungsten-halogen (QTH) or light-emitting diodes (LED) light-curing unit (LCU) and using dentin thicknesses (0.5 and 1.0 mm). Standardized cavities (2x2x2 mm) were prepared in 80 bovine incisors, which were randomly assigned to 8 groups according to the photoactivation method and dentin thickness. Filtek P90 and Heliomolar (both in shade A3) were used with their respective adhesive systems (P90 self-etch primer / P90 adhesive bond and Excite adhesive). All experiments were carried out in a controlled environment (37°C). The temperature variations (°C) were recorded using a digital thermometer attached to a K-type thermocouple. The results were analyzed statistically by ANOVA and Tukey's test (α=0.05). For composite/dentin thickness interaction, temperature increase was significantly higher in 0.5 mm dentin thickness (40.07°C) compared with 1.0 mm dentin thickness (39.61°C) for Filtek P90. For composite/LCU interaction, the temperature increase was significantly higher for Filtek P90 (39.21°C - QTH and 40.47°C - LED) compared with Heliomolar (38.40°C - QTH and 39.30°C - LED). The silorane-based composite promoted higher temperature increase in the pulp chamber than the methacrylate-based composite.

  17. Composite structures of steel and concrete beams, slabs, columns, and frames for buildings

    CERN Document Server

    Johnson, R P

    2008-01-01

    This book sets out the basic principles of composite construction with reference to beams, slabs, columns and frames, and their applications to building structures. It deals with the problems likely to arise in the design of composite members in buildings, and relates basic theory to the design approach of Eurocodes 2, 3 and 4.The new edition is based for the first time on the finalised Eurocode for steel/concrete composite structures.

  18. Analysis and seismic tests of composite shear walls with CFST columns and steel plate deep beams

    Science.gov (United States)

    Dong, Hongying; Cao, Wanlin; Wu, Haipeng; Zhang, Jianwei; Xu, Fangfang

    2013-12-01

    A composite shear wall concept based on concrete filled steel tube (CFST) columns and steel plate (SP) deep beams is proposed and examined in this study. The new wall is composed of three different energy dissipation elements: CFST columns; SP deep beams; and reinforced concrete (RC) strips. The RC strips are intended to allow the core structural elements — the CFST columns and SP deep beams — to work as a single structure to consume energy. Six specimens of different configurations were tested under cyclic loading. The resulting data are analyzed herein. In addition, numerical simulations of the stress and damage processes for each specimen were carried out, and simulations were completed for a range of location and span-height ratio variations for the SP beams. The simulations show good agreement with the test results. The core structure exhibits a ductile yielding mechanism characteristic of strong column-weak beam structures, hysteretic curves are plump and the composite shear wall exhibits several seismic defense lines. The deformation of the shear wall specimens with encased CFST column and SP deep beam design appears to be closer to that of entire shear walls. Establishing optimal design parameters for the configuration of SP deep beams is pivotal to the best seismic behavior of the wall. The new composite shear wall is therefore suitable for use in the seismic design of building structures.

  19. CURING EFFICIENCY OF DUAL-CURE RESIN CEMENT UNDER ZIRCONIA WITH TWO DIFFERENT LIGHT CURING UNITS

    Directory of Open Access Journals (Sweden)

    Pınar GÜLTEKİN

    2015-04-01

    Full Text Available Purpose: Adequate polymerization is a crucial factor in obtaining optimal physical properties and a satisfying clinical performance from composite resin materials. The aim of this study was to evaluate the polymerization efficiency of dual-cure resin cement cured with two different light curing units under zirconia structures having differing thicknesses. Materials and Methods: 4 zirconia discs framework in 4 mm diameter and in 0.5 mm, 1 mm and 1.5 mm thickness were prepared using computer-aided design system. One of the 0.5 mm-thick substructures was left as mono-layered whereas others were layered with feldspathic porcelain of same thickness and ceramic samples with 4 different thicknesses (0.5, 1, 1.5 and 2.0 mm were prepared. For each group (n=12 resin cement was light cured in polytetrafluoroethylene molds using Light Emitting Diode (LED or Quartz-Tungsten Halogen (QHT light curing units under each of 4 zirconia based discs (n=96. The values of depth of cure (in mm and the Vickers Hardness Number values (VHN were evaluated for each specimen. Results: The use of LED curing unit produced a greater depth of cure compared to QTH under ceramic discs with 0.5 and 1 mm thickness (p<0.05.At 100μm and 300 μm depth, the LED unit produced significantly greater VHN values compared to the QTH unit (p<0.05. At 500 μm depth, the difference between the VHN values of LED and QTH groups were not statistically significant. Conclusion: Light curing may not result in adequate resin cement polymerization under thick zirconia structures. LED light sources should be preferred over QTH for curing dual-cure resin cements, especially for those under thicker zirconia restorations.

  20. Monitoring Prepregs As They Cure

    Science.gov (United States)

    Young, P. R.; Gleason, J. R.; Chang, A. C.

    1986-01-01

    Quality IR spectra obtained in dynamic heating environment. New technique obtains quality infrared spectra on graphite-fiber-reinforced, polymeric-matrix-resin prepregs as they cure. Technique resulted from modification of diffuse reflectance/Fourier transform infrared (DR/FTIR) technique previously used to analyze environmentally exposed cured graphite composites. Technique contribute to better understanding of prepreg chemistry/temperature relationships and development of more efficient processing cycles for advanced materials.

  1. The effect of material heterogeneity in curved composite beams for use in aircraft structures

    Science.gov (United States)

    Otoole, Brendan J.; Santare, Michael H.

    1992-01-01

    A design tool is presented for predicting the effect of material heterogeneity on the performance of curved composite beams for use in aircraft fuselage structures. Material heterogeneity can be induced during processes such as sheet forming and stretch forming of thermoplastic composites. This heterogeneity can be introduced in the form of fiber realignment and spreading during the manufacturing process causing a gradient in material properties in both the radial and tangential directions. The analysis procedure uses a separate two-dimensional elasticity solution for the stresses in the flanges and web sections of the beam. The separate solutions are coupled by requiring the forces and displacements match at the section boundaries. Analysis is performed for curved beams loaded in pure bending and uniform pressure. The beams can be of any general cross-section such as a hat, T-, I-, or J-beam. Preliminary results show that geometry of the beam dictates the effect of heterogeneity on performance. Heterogeneity plays a much larger role in beams with a small average radius to depth ratio, R/t, where R is the average radius of the beam and t is the difference between the inside and outside radius. Results of the analysis are in the form of stresses and displacements, and they are compared to both mechanics of materials and numerical solutions obtained using finite element analysis.

  2. Radiation cured acrylonitrile--butadiene elastomers

    International Nuclear Information System (INIS)

    Eldred, R.J.

    1976-01-01

    In accordance with a preferred embodiment of this invention, the ultimate elongation of an electron beam radiation cured acrylonitrile-butadiene elastomer is significantly increased by the incorporation of a preferred noncrosslinking monomer, glycidyl methacrylate, in combination with the conventional crosslinking monomer, trimethylolpropanetrimethacrylate, prior to the radiation curing process

  3. Characterization of compressive and short beam shear strength of bamboo opened cell foam core sandwich composites

    Energy Technology Data Exchange (ETDEWEB)

    Setyawan, Paryanto Dwi, E-mail: paryanto-ds@yahoo.com; Sugiman,; Saputra, Yudhi [Department of Mechanical Engineering, Faculty of Engineering, University of Mataram, Mataram, West Nusa Tenggara (Indonesia)

    2016-03-29

    The paper presents the compressive and the short beam shear strength of a sandwich composite with opened cell foam made of bamboo fiber as the core and plywood as the skins. The core thickness was varied from 10 mm to 40 mm keeping the volume fraction of fiber constant. Several test s were carried out including the core density, flatwise compressive and the short beam shear testing in three point bending. The results show that the density of bamboo opened cell foam is comparable with commercial plastic foam, such as polyurethane foam. The compressive strength tends to increase linearly with increasing the core thickness. The short beam shear failure load of the sandwich composite increases with the increase of core thickness, however on the contrary, the short beam shear strength which tends to sharply decrease from the thickness of 10 mm to 30 mm and then becomes flat.

  4. A Numerical Analysis of the Resistance and Stiffness of the Timber and Concrete Composite Beam

    Science.gov (United States)

    Szumigała, Ewa; Szumigała, Maciej; Polus, Łukasz

    2015-03-01

    The article presents the results of a numerical analysis of the load capacity and stiffness of the composite timber and concrete beam. Timber and concrete structures are relatively new, they have not been thoroughly tested and they are rarely used because of technological constraints. One of the obstacles to using them is difficulty with finding a method which would allow successful cooperation between concrete and timber, which has been proposed by the authors of the present article. The modern idea of sustainable construction design requires the use of new more environmentally-friendly solutions. Wood as an ecological material is easily accessible, less energy-consuming, and under certain conditions more corrosion-resistant than steel. The analysis presented in the article showed that cooperation between a wooden beam and a concrete slab on profiled steel sheeting is possible. The analysed composite beam has a greater load capacity and stiffness than the wooden beam.

  5. A Numerical Analysis of the Resistance and Stiffness of the Timber and Concrete Composite Beam

    Directory of Open Access Journals (Sweden)

    Szumigała Ewa

    2015-03-01

    Full Text Available The article presents the results of a numerical analysis of the load capacity and stiffness of the composite timber and concrete beam. Timber and concrete structures are relatively new, they have not been thoroughly tested and they are rarely used because of technological constraints. One of the obstacles to using them is difficulty with finding a method which would allow successful cooperation between concrete and timber, which has been proposed by the authors of the present article. The modern idea of sustainable construction design requires the use of new more environmentally-friendly solutions. Wood as an ecological material is easily accessible, less energy-consuming, and under certain conditions more corrosion-resistant than steel. The analysis presented in the article showed that cooperation between a wooden beam and a concrete slab on profiled steel sheeting is possible. The analysed composite beam has a greater load capacity and stiffness than the wooden beam.

  6. Flexural Behavior of RC Members Using Externally Bonded Aluminum-Glass Fiber Composite Beams

    Directory of Open Access Journals (Sweden)

    Ki-Nam Hong

    2014-03-01

    Full Text Available This study concerns improvement of flexural stiffness/strength of concrete members reinforced with externally bonded, aluminum-glass fiber composite (AGC beams. An experimental program, consisting of seven reinforced concrete slabs and seven reinforced concrete beams strengthened in flexure with AGC beams, was initiated under four-point bending in order to evaluate three parameters: the cross-sectional shape of the AGC beam, the glass fiber fabric array, and the installation of fasteners. The load-deflection response, strain distribution along the longitudinal axis of the beam, and associated failure modes of the tested specimens were recorded. It was observed that the AGC beam led to an increase of the initial cracking load, yielding load of the tension steels and peak load. On the other hand, the ductility of some specimens strengthened was reduced by more than 50%. The A-type AGC beam was more efficient in slab specimens than in beam specimens and the B-type was more suitable for beam specimens than for slabs.

  7. Composite optical vortices in noncollinear Laguerre–Gaussian beams and their propagation in free space

    International Nuclear Information System (INIS)

    Chen Ke; Liu Pusheng; Lü Baida

    2008-01-01

    Taking two Laguerre—Gaussian beams with topological charge l = ± 1 as an example, this paper studies the composite optical vortices formed by two noncollinear Laguerre—Gaussian beams with different phases, amplitudes, waist widths, off-axis distances, and their propagation in free space. It is shown by detailed numerical illustrative examples that the number and location of composite vortices at the waist plane are variable by varying the relative phase β, amplitude ratio η, waist width ratio ζ, or off-axis distance ratio μ. The net topological charge l net is not always equal to the sum l sum of charges of the two component beams. The motion, creation and annihilation of composite vortices take place in the free-space propagation, and the net charge during the propagation remains unchanged and equals to the net charge at the waist plane

  8. Investigation of the composition of an ion beam produced using a multi arc ion source

    Energy Technology Data Exchange (ETDEWEB)

    Engelko, V [Efremov Institute of Electrophysical Apparatus, St. Petersburg (Russian Federation); Giese, H; Schalk, S [Forschungszentrum Karlsruhe (Germany). INR; Mishin, M; Tsibin, O Y [St. Petersburg State Technical Univ. (Russian Federation)

    1997-12-31

    Complementing the diode and beam transport optimization studies currently performed at FZK Karlsruhe on the proton-beam-facility PROFA, supplementary investigations were run at the St. Petersburg State University, focusing on ion beam divergence and composition measurements using the TOF techniques. To ensure direct transferability of the results to the PROFA facility, these measurements were made on a scaled-down replica of the PROFA diode, comprising an array of small polyethylene flash-over plasma sources and a grid extraction system. Only the results of the beam composition measurements are presented, and the following conclusions are made: (i) The ion beam contains H and C ions and heavier constituents that remain to be identified. (ii) The beam composition changes significantly with the total number of shots: While H{sup +} ions predominated in the starting phase of the experiments, heavier components outweighed them later on, presumably due to hydrogen depletion of the surface layer of the anode polyethylene units. (iii) Reconditioning of the polyethylene units may be possible by running the diode at higher currents (self-cleaning) or by cutting off a surface layer. (author). 7 figs., 3 refs.

  9. Structural modelling of composite beams with application to wind turbine rotor blades

    DEFF Research Database (Denmark)

    Couturier, Philippe

    The ever changing structure and growing size of wind turbine blades put focus on the accuracy and flexibility of design tools. The present thesis is organized in four parts - all concerning the development of efficient computational methods for the structural modelling of composite beams which...... will support future growth in the rotor size.The first part presents a two-node beam element formulation, based on complementary elastic energy, valid for fully coupled beams with variable cross-section properties.The element stiffness matrix is derived by use of the six equilibrium states of the element...

  10. Analytical, Numerical and Experimental Examination of Reinforced Composites Beams Covered with Carbon Fiber Reinforced Plastic

    Science.gov (United States)

    Kasimzade, A. A.; Tuhta, S.

    2012-03-01

    In the article, analytical, numerical (Finite Element Method) and experimental investigation results of beam that was strengthened with fiber reinforced plastic-FRP composite has been given as comparative, the effect of FRP wrapping number to the maximum load and moment capacity has been evaluated depending on this results. Carbon FRP qualitative dependences have been occurred between wrapping number and beam load and moment capacity for repair-strengthen the reinforced concrete beams with carbon fiber. Shown possibilities of application traditional known analysis programs, for the analysis of Carbon Fiber Reinforced Plastic (CFRP) strengthened structures.

  11. NUMERICAL PREDICTION OF COMPOSITE BEAM SUBJECTED TO COMBINED NEGATIVE BENDING AND AXIAL TENSION

    Directory of Open Access Journals (Sweden)

    MAHESAN BAVAN

    2013-08-01

    Full Text Available The present study has investigated the finite element method (FEM techniques of composite beam subjected to combined axial tension and negative bending. The negative bending regions of composite beams are influenced by worsen failures due to various levels of axial tensile loads on steel section especially in the regions near internal supports. Three dimensional solid FEM model was developed to accurately predict the unfavourable phenomenon of cracking of concrete and compression of steel in the negative bending regions of composite beam due to axial tensile loads. The prediction of quasi-static solution was extensively analysed with various deformation speeds and energy stabilities. The FEM model was then validated with existing experimental data. Reasonable agreements were observed between the results of FEM model and experimental analysis in the combination of vertical-axial forces and failure modes on ultimate limit state behaviour. The local failure modes known as shear studs failure, excess yielding on steel beam and crushing on concrete were completely verified by extensive similarity between the numerical and experimental results. Finally, a proper way of modelling techniques for large FEM models by considering uncertainties of material behaviour due to biaxial loadings and complex contact interactions is discussed. Further, the model is suggested for the limit state prediction of composite beam with calibrating necessary degree of the combined axial loads.

  12. Application of Conjugate Simulation for Determination of Temperature and Stress Distributions During Curing Process of Pre-Impregnated Composite Fibers

    Directory of Open Access Journals (Sweden)

    Golewski P.

    2017-12-01

    Full Text Available The composites made of continuous fibers in the form of unidirectional and fabric prepregs are widely used in many fields of engineering for the production of lightweight and durable parts or whole structures. To achieve this, we not only need to possess knowledge of the composite mechanics, but also have to master the technology. In most cases, particularly for parts with advanced geometric shapes, autoclaving technique is used. The success of the carried out process occurs when the prepreg reaches the proper temperature throughout its volume in the specified time, where there are no overheated or unheated zones as well as when the prepreg is correctly pressed against the mold. In order to ensure adequate stiffness, the mold has much greater thickness than formed composite and the stiffening ribs. The result is that the time required for prepreg heating is greatly extended. To prevent this, the appropriate electric heaters embedded in the silicone grips are used.

  13. Dynamic analysis of smart composite beams by using the frequency domain spectral element method

    Energy Technology Data Exchange (ETDEWEB)

    Park, Il Wook; Lee, Usik [Inha Univ., Incheon (Korea, Republic of)

    2012-08-15

    To excite or measure the dynamic responses of a laminated composite structure for the active controls of vibrations or noises, wafertype piezoelectric transducers are often bonded on the surface of the composite structure to form a multi layer smart composite structure. Thus, for such smart composite structures, it is very important to develop and use a very reliable mathematical and/or computational model for predicting accurate dynamic characteristics. In this paper, the axial-bending coupled equations of motion and boundary conditions are derived for two layer smart composite beams by using the Hamilton's principle with Lagrange multipliers. The spectral element model is then formulated in the frequency domain by using the variation approach. Through some numerical examples, the extremely high accuracy of the present spectral element model is verified by comparing with the solutions by the conventional finite element model provided in this paper. The effects of the lay up of composite laminates and surface bonded wafer type piezoelectric (PZT) layer on the dynamics and wave characteristics of smart composite beams are investigated. The effective constraint forces at the interface between the base beam and PZT layer are also investigated via Lagrange multipliers.

  14. UV/EB curing market in Indonesia

    International Nuclear Information System (INIS)

    Hilmy, N.; Danu, S.

    1999-01-01

    The most application of UV curing of surface coating in Indonesia are on fancy plywood, furniture and wood flooring industry. Other application are on papers, printing ink/labelling, printed circuit board/PCB and dental materials. At present, application of EB curing coating is still in a pilot plant scale due to the high cost of production. Limited number of application of EB curing by using low energy electron beam machine are on wood panels, ceramics and marbles. This paper describes the market and the problem faced by the largest user of radiation curing systems such as the secondary process plywood, furniture and paper industries

  15. Efficacy of Thermally Conditioned Sisal FRP Composite on the Shear Characteristics of Reinforced Concrete Beams

    Directory of Open Access Journals (Sweden)

    Tara Sen

    2013-01-01

    Full Text Available The development of commercially viable composites based on natural resources for a wide range of applications is on the rise. Efforts include new methods of production and the utilization of natural reinforcements to make biodegradable composites with lignocellulosic fibers, for various engineering applications. In this work, thermal conditioning of woven sisal fibre was carried out, followed by the development of woven sisal fibre reinforced polymer composite system, and its tensile and flexural behaviour was characterized. It was observed that thermal conditioning improved the tensile strength and the flexural strength of the woven sisal fibre composites, which were observed to bear superior values than those in the untreated ones. Then, the efficacy of woven sisal fibre reinforced polymer composite for shear strengthening of reinforced concrete beams was evaluated using two types of techniques: full and strip wrapping techniques. Detailed analysis of the load deflection behaviour and fracture study of reinforced concrete beams strengthened with woven sisal under shearing load were carried out, and it was concluded that woven sisal FRP strengthened beams, underwent very ductile nature of failure, without any delamination or debonding of sisal FRP, and also increased the shear strength and the first crack load of the reinforced concrete beams.

  16. Development of a wood-polymer composite by electron beam hardening

    International Nuclear Information System (INIS)

    Gotoda, Masao

    1974-01-01

    An incombustible wood-polymer composite (WPC) was studied. The dimensional stability was also tested. The comparison of conversion ratio was made between gamma-ray and electron beam and between a vinylidene chloride 100% impregnated beech composite and bulk. In the case of gamma-ray of low dose rate, the conversion ratio in the vinylidene chloride beech composite was lower than the bulk. In the case of electron beam, though dose rate was higher than that of gamma-ray, the conversion ratio was low, and was influenced by the moisture content of wood. The conversion ratio markedly decreased with the increase of the dose rate of electron beam. Roughly 50% polymer loading can be obtained when the dose rate of electron beam is low. In the case of gamma-ray, the effect of dimensional stability was approximately none with small polymer loading, whereas in the case of electron beam irradiation of moist wood, marked effect of dimensional stability was shown. Incombustibility effect was tested by burning a 150 mm long piece, in which three small pieces of 5 x 10 x 50 mm were connected with epoxy resin adhesive, with a Bunsen burner for 30 seconds. After the completion of burning, the long piece was separated back into three small pieces, and the char length, weight loss and after glow time were tested. The beech composite was expected to become incombustible at 40% polymer loading. The vinyl monomer solution of chlorinated aryl chloride oligomer can be easily hardened by electron beam irradiation. Addition of crosslinking agent such as trimethylol propane trimethracrylate prevents the dissolution of hardened methyl acrylate and methyl methacrylate by acetone. The electron beam hardening of aryl resin compound is possible, using benzen peroxide as a catalyst. Floor material can be produced by this process from low density, low price wood. (Iwakiri, K.)

  17. Composite beam analysis linear analysis of naturally curved and twisted anisotropic beams

    Science.gov (United States)

    Borri, Marco; Ghiringhelli, Gian L.; Merlini, Teodoro

    1992-05-01

    The aim of this report is to present a consistent theory for the deformation of a naturally curved and twisted anisotropic beam. The proposed formulation naturally extends the classical Saint-Venant approach to the case of curved and twisted anisotropic beams. The mathematical model developed under the assumption of span-wise uniform cross-section, curvature and twist, can take into account any kind of elastic coupling due to the material properties and the curved geometry. The consistency of the presented math-model and its generality about the cross-sectional shape, make it a useful tool even in a preliminary design optimization context such as the aeroelastic tailoring of helicopter rotor blades. The advantage of the present procedure is that it only requires a two-dimensional discretization; thus, very detailed analyses can be performed and interlaminar stresses between laminae can be evaluated. Such analyses would be extremely time consuming if performed with standard finite element codes: that prevents their recursive use as for example when optimizing a beam design. Moreover, as a byproduct of the proposed formulation, one obtains the constitutive law of the cross-section in terms of stress resultant and moment and their conjugate strain measures. This constitutive law takes into account any kind of elastic couplings, e.g., torsion-tension, tension-shear, bending-shear, and constitutes a fundamental input in aeroelastic analyses of helicopter blades. Four simple examples are given in order to show the principal features of the method.

  18. Energy composition of high-energy neutral beams on the COMPASS tokamak

    Directory of Open Access Journals (Sweden)

    Mitosinkova Klara

    2016-12-01

    Full Text Available The COMPASS tokamak is equipped with two identical neutral beam injectors (NBI for additional plasma heating. They provide a beam of deuterium atoms with a power of up to ~(2 × 300 kW. We show that the neutral beam is not monoenergetic but contains several energy components. An accurate knowledge of the neutral beam power in each individual energy component is essential for a detailed description of the beam- -plasma interaction and better understanding of the NBI heating processes in the COMPASS tokamak. This paper describes the determination of individual energy components in the neutral beam from intensities of the Doppler-shifted Dα lines, which are measured by a high-resolution spectrometer viewing the neutral beam-line at the exit of NBI. Furthermore, the divergence of beamlets escaping single aperture of the last accelerating grid is deduced from the width of the Doppler-shifted lines. Recently, one of the NBI systems was modified by the removal of the Faraday copper shield from the ion source. The comparison of the beam composition and the beamlet divergence before and after this modification is also presented.

  19. Finite element analysis of composite beam-to-column connection with cold-formed steel section

    Science.gov (United States)

    Firdaus, Muhammad; Saggaff, Anis; Tahir, Mahmood Md

    2017-11-01

    Cold-formed steel (CFS) sections are well known due to its lightweight and high structural performance which is very popular for building construction. Conventionally, they are used as purlins and side rails in the building envelopes of the industrial buildings. Recent research development on cold-formed steel has shown that the usage is expanded to the use in composite construction. This paper presents the modelling of the proposed composite connection of beam-to-column connection where cold-formed steel of lipped steel section is positioned back-to-back to perform as beam. Reinforcement bars is used to perform the composite action anchoring to the column and part of it is embedded into a slab. The results of the finite element and numerical analysis has showed good agreement. The results show that the proposed composite connection contributes to significant increase to the moment capacity.

  20. Influence of light-exposure methods and depths of cavity on the microhardness of dual-cured core build-up resin composites

    Directory of Open Access Journals (Sweden)

    Keiichi YOSHIDA

    2014-01-01

    Full Text Available Objective: The purpose of this study was to evaluate the Knoop hardness number (KHN of dual-cured core build-up resin composites (DCBRCs at 6 depths of cavity after 3 post-irradiation times by 4 light-exposure methods. Material and Methods: Five specimens each of DCBRCs (Clearfil DC Core Plus [DCP] and Unifil Core EM [UCE] were filled in acrylic resin blocks with a semi-cylindrical cavity and light-cured using an LED light unit (power density: 1,000 mW/cm2at the top surface by irradiation for 20 seconds (20 s, 40 seconds (40 s, bonding agent plus 20 seconds (B+20 s, or 40 seconds plus light irradiation of both sides of each acrylic resin block for 40 seconds each (120 s. KHN was measured at depths of 0.5, 2.0, 4.0, 6.0, 8.0, and 10.0 mm at 0.5 hours, 24 hours, and 7 days post-irradiation. Statistical analysis was performed using repeated measures ANOVA and Tukey's compromise post-hoc test with a significance level of p0.05. In DCP, and not UCE, at 24 hours and 7 days post-irradiation, the B+20 s method showed significantly higher KHN at all depths of cavity, except the depth of 0.5 mm (p<0.05. Conclusion: KHN depends on the light-exposure method, use of bonding agent, depth of cavity, post-irradiation time, and material brand. Based on the microhardness behavior, DCBRCs are preferably prepared by the effective exposure method, when used for a greater depth of cavity.

  1. Effects of radiant exposure values using second and third generation light curing units on the degree of conversion of a lucirin-based resin composite.

    Science.gov (United States)

    Cardoso, Kelly Antonieta Oliveira Rodrigues de Faria; Zarpellon, Driellen Christine; Madruga, Camila Ferreira Leite; Rodrigues, José Augusto; Arrais, Cesar Augusto Galvão

    2017-01-01

    Using Fourier transform infrared analysis (FTIR) in vitro, the effects of varying radiant exposure (RE) values generated by second and third generation LED LCUs on the degree of conversion (DC) and maximum rate of polymerization (Rpmax) of an experimental Lucirin TPO-based RC were evaluated. 1 mm or 2 mm thick silicon molds were positioned on a horizontal attenuated total reflectance (ATR) unit attached to an infrared spectroscope. The RC was inserted into the molds and exposed to varying REs (18, 36 and 56 J/cm2) using second (Radii Plus, SDI) and third generation LED LCUs (Bluephase G2/Ivoclar Vivadent) or a quartz tungsten based LCU (Optilux 501/SDS Kerr). FTIR spectra (n=7) were recorded for 10 min (1 spectrum/s, 16 scans/spectrum, resolution 4 cm-1) immediately after their application to the ATR. The DC was calculated using standard techniques for observing changes in aliphatic to aromatic peak ratios both prior to, and 10 min after curing, as well as during each 1 second interval. DC and Rpmax data were analyzed using 3-way ANOVA and Tukey's post-hoc test (p=0.05). No significant difference in DC or Rpmax was observed between the 1 mm or 2 mm thick specimens when RE values were delivered by Optilux 501 or when the 1 mm thick composites were exposed to light emitted by Bluephase G2, which in turn promoted a lower DC when 18 J/cm2 (13 s) were delivered to the 2 mm thick specimens. Radii Plus promoted DC and Rpmax values close to zero under most conditions, while the delivery of 56 J/cm2 (40 s) resulted in low DC values. The third generation LCU provided an optimal polymerization of Lucirin TPO-based RC under most tested conditions, whereas the second generation LED-curing unit was useless regardless of the RE.

  2. Elastic and transport properties of steam-cured pozzolanic-lime rock composites upon CO2 injection

    Science.gov (United States)

    Emery, Dan; Vanorio, Tiziana

    2016-04-01

    Understanding the relationship between pozzolanic ash-lime reactions and the rock physics properties of the resulting rock microstructure is important for monitoring unrest conditions in volcanic-hydrothermal systems as well as devising concrete with enhanced performance. By mixing pozzolanic ash with lime, the ancient Romans incorporated these reactions in the production of concrete. Recently, it has been discovered that a fiber-reinforced, concrete-like rock is forming naturally in the depths of the Campi Flegrei volcanic-hydrothermal systems (Vanorio and Kanitpanyacharoen, 2015). We investigate the physico-chemical conditions contributing to undermine or enhance the laboratory measured properties of the subsurface rocks of volcanic-hydrothermal systems and, in turn, build upon those processes that the ancient Romans unwittingly exploited to create their famous concrete. We prepared samples by mixing the pozzolana volcanic ash, slaked lime, aggregates of Neapolitan Yellow tuff, and seawater from Campi Flegrei in the same ratios as the ancient Romans. To mimic the conditions of the caldera, we used mineral seawater from a well in the Campi Flegrei region rich in sulfate, bicarbonate, calcium, potassium, and magnesium ions. The samples were cured by steam. We measured baseline properties of porosity, permeability, P-wave velocity, and S-wave velocity of the samples. P and S-wave velocities were used to derive bulk, shear, and Young's moduli. Subsequently, half of the samples were injected with CO2-rich aqueous solution and the changes in their microstructure and physical properties measured. One sample was subjected to rapid temperature changes to determine how porosity and permeability changed as a function of the number of thermal shocks. Exposure of CO2 to the concrete-like rock samples destabilized fibrous mineral forming and decreased the samples' ability to deform without breaking. We show that steam- and sulfur-alkaline- rich environments affect both

  3. Vibration Analysis of Steel-Concrete Composite Box Beams considering Shear Lag and Slip

    Directory of Open Access Journals (Sweden)

    Zhou Wangbao

    2015-01-01

    Full Text Available In order to investigate dynamic characteristics of steel-concrete composite box beams, a longitudinal warping function of beam section considering self-balancing of axial forces is established. On the basis of Hamilton principle, governing differential equations of vibration and displacement boundary conditions are deduced by taking into account coupled influencing of shear lag, interface slip, and shear deformation. The proposed method shows an improvement over previous calculations. The central difference method is applied to solve the differential equations to obtain dynamic responses of composite beams subjected to arbitrarily distributed loads. The results from the proposed method are found to be in good agreement with those from ANSYS through numerical studies. Its validity is thus verified and meaningful conclusions for engineering design can be drawn as follows. There are obvious shear lag effects in the top concrete slab and bottom plate of steel beams under dynamic excitation. This shear lag increases with the increasing degree of shear connections. However, it has little impact on the period and deflection amplitude of vibration of composite box beams. The amplitude of deflection and strains in concrete slab reduce as the degree of shear connections increases. Nevertheless, the influence of shear connections on the period of vibration is not distinct.

  4. Interfacial damage identification of steel and concrete composite beams based on piezoceramic wave method.

    Science.gov (United States)

    Yan, Shi; Dai, Yong; Zhao, Putian; Liu, Weiling

    2018-01-01

    Steel-concrete composite structures are playing an increasingly important role in economic construction because of a series of advantages of great stiffness, good seismic performance, steel material saving, cost efficiency, convenient construction, etc. However, in service process, due to the long-term effects of environmental impacts and dynamic loading, interfaces of a composite structure might generate debonding cracks, relative slips or separations, and so on, lowering the composite effect of the composite structure. In this paper, the piezoceramics (PZT) are used as transducers to perform experiments on interface debonding slips and separations of composite beams, respectively, aimed at proposing an interface damage identification model and a relevant damage detection innovation method based on PZT wave technology. One part of various PZT patches was embedded in concrete as "smart aggregates," and another part of the PZT patches was pasted on the surface of the steel beam flange, forming a sensor array. A push-out test for four specimens was carried out and experimental results showed that, under the action of the external loading, the received signal amplitudes will increasingly decrease with increase of debonding slips along the interface. The proposed signal energy-based interface damage detection algorithm is highly efficient in surface state evaluations of composite beams.

  5. Vibration Analysis of Inclined Laminated Composite Beams under Moving Distributed Masses

    Directory of Open Access Journals (Sweden)

    E. Bahmyari

    2014-01-01

    Full Text Available The dynamic response of laminated composite beams subjected to distributed moving masses is investigated using the finite element method (FEM based on the both first-order shear deformation theory (FSDT and the classical beam theory (CLT. Six and ten degrees of freedom beam elements are used to discretize the CLT and FSDT equations of motion, respectively. The resulting spatially discretized beam governing equations including the effect of inertial, Coriolis, and centrifugal forces due to moving distributed mass are evaluated in time domain by applying Newmark’s scheme. The presented approach is first validated by studying its convergence behavior and comparing the results with those of existing solutions in the literature. Then, the effect of incline angle, mass, and velocity of moving body, layer orientation, load length, and inertial, Coriolis, and centrifugal forces due to the moving distributed mass and friction force between the beam and the moving distributed mass on the dynamic behavior of inclined laminated composite beams are investigated.

  6. Woven type smart soft composite beam with in-plane shape retention

    International Nuclear Information System (INIS)

    Wu, Renzhe; Han, Min-Woo; Lee, Gil-Yong; Ahn, Sung-Hoon

    2013-01-01

    Shape memory alloy (SMA) wire embedded composites (SMAECs) are widely used as morphing structures in small-size and high-output systems. However, conventional SMAECs cannot keep deformed shapes without additional energy. In this paper, a new kind of smart structure named the woven type smart soft composite (SSC) beam is introduced, which is not only capable of morphing, but also maintaining its deformed shape without additional energy. The woven type SSC beam consists of two parts: woven wires and matrix. The selected woven wires are nitinol (Ni–Ti) SMA wires and glass fibers, while the matrix part is polydimethylsiloxane (PDMS). In order to evaluate the performance of the woven type SSC beam in areas such as in-plane deformation, blocking force and repeatability, a beam-shape specimen is prepared of size 100 mm (length) × 8 mm (width) ×3 mm (thickness). The fabricated SSC beam achieved 21 mm deformation and 16 mm shape retention. Blocking force was measured using a dynamometer, and was about 60 mN. In the repeatability test, it recovered almost the same position when its cooling time was 90 s more. Consequently, the woven type SSC beam can be applied to bio-mimicking, soft morphing actuators, consuming less energy than traditional SMAECs. (paper)

  7. Evaluation of the Impact Resistance of Various Composite Sandwich Beams by Vibration Tests

    Directory of Open Access Journals (Sweden)

    Amir Shahdin

    2011-01-01

    Full Text Available Impact resistance of different types of composite sandwich beams is evaluated by studying vibration response changes (natural frequency and damping ratio. This experimental works will help aerospace structural engineer in assess structural integrity using classification of impact resistance of various composite sandwich beams (entangled carbon and glass fibers, honeycomb and foam cores. Low velocity impacts are done below the barely visible impact damage (BVID limit in order to detect damage by vibration testing that is hardly visible on the surface. Experimental tests are done using both burst random and sine dwell testing in order to have a better confidence level on the extracted modal parameters. Results show that the entangled sandwich beams have a better resistance against impact as compared to classical core materials.

  8. A study on chemical composition of spices irradiated by electron beam

    International Nuclear Information System (INIS)

    Ding Lianzhong; Ding Shiyue; Zhu Yan; Li Yixu; Zhu Songmei

    1998-01-01

    Quantitative changes in common organic acids and inorganic acids from spices irradiated by electron beam were studied by Dionex-4000i ion chromatograph. The results showed that the acids content of either chilli or the five-spice powder irradiated with a dose of 9.94 kGy did not undergo significant changes in comparison with the control samples. The flavour composition in the five-spice powder irradiated by electron beam was also determined by Finnigan MAT-8230B gas chromatograph-mass spectrometer, and compared to the results by heating treatment (120 deg. C, 30min). The comparison indicated that the effect of electron beam treatment on flavour composition was less than that of heating

  9. A study on chemical composition of spices irradiated by electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Lianzhong, Ding [Inst. of Applied Technical Physics of Zhejiang Province (China); Shiyue, Ding; Yan, Zhu; Yixu, Li [Testing Technology Inst. of Zhejiang Province (China)

    1992-02-01

    Quantitative changes in common organic acids and inorganic acids from spices irradiated by electron beam were studied by Dionex-4000 ion Chromatograph. The results showed that the acids content of either achilli or the five-spice powder irradiated with a dose of 9.94 kGy did not undergo significant changes in comparison with the control samples. The flavour composition in the five-spice powder irradiated by electron beam was also determined by Finnigan MAT-8230B gas chromatograph-mass spectrometer, and compared to the results by heating treatment (120 C, 30 min). The comparison indicated that the effect of electron beam treatment on flavour composition was less than that of heating.

  10. Dynamic behavior of a rotating delaminated composite beam including rotary inertia and shear deformation effects

    Directory of Open Access Journals (Sweden)

    Ramazan-Ali Jafari-Talookolaei

    2015-09-01

    Full Text Available A finite element (FE model is developed to study the free vibration of a rotating laminated composite beam with a single delamination. The rotary inertia and shear deformation effects, as well as the bending–extension, bending–twist and extension–twist coupling terms are taken into account in the FE model. Comparison between the numerical results of the present model and the results published in the literature verifies the validity of the present model. Furthermore, the effects of various parameters, such as delamination size and location, fiber orientation, hub radius, material anisotropy and rotating speed, on the vibration of the beam are studied in detail. These results provide useful information in the study of the free vibration of rotating delaminated composite beams.

  11. Holographic Formation of Diffraction Elements for Transformation of Light Beams in Liquid Crystal - Photopolymer Compositions

    Science.gov (United States)

    Semkin, A. O.; Sharangovich, S. N.

    2018-03-01

    A theoretical model of holographic formation of diffractive optical elements for transformation of light beam field into Bessel-like fields in liquid crystal - photopolymer (LC-PPM) composite materials with a dyesensitizer is developed. Results of numerical modeling of kinetics ofvariation of the refractive index of a material in the process of formation with different relationships between the photopolymerization rates and diffusion processes are presented. Based on the results of numerical simulation, it is demonstrated that when the photopolarization process dominates, the diffractive element being formed is distorted. This leads to a change in the light field distribution at its output and consequently, to ineffective transformation of the reading beam. Thus, the necessity of optimizing of the recording conditions and of the prepolymeric composition to increase the transformation efficiency of light beam fields is demonstrated.

  12. Computer module for scheduling of transportation of composite beam bridge structures

    Directory of Open Access Journals (Sweden)

    Bożejko Wojciech

    2016-01-01

    Full Text Available The paper presents the theoretical basis, an algorithm and a computer module system supporting scheduling of transportation and assembly of structures of the composite beam bridge implemented in a Just In Time system (JIT. Tabu search method has been used in the optimization procedure.

  13. Effects of electron-beam irradiation on HDPE/Brazil nut shell fiber composite

    International Nuclear Information System (INIS)

    Ferreira, Maiara S.; Sartori, Mariana N.; Oliveira, Rene R.; Moura, Esperidiana A.B.

    2013-01-01

    In recent years, research on the replacement of synthetic fibers by natural fibers as reinforcement in thermoplastic composites has increased dramatically due to the advantages of natural fibers, such as low density, low cost, environmental appeal and recyclability. In the present work, the influence of electron-beam irradiation on mechanical properties of HDPE and HDPE/Brazil Nut Shell (Bertholletia excelsa) fiber compositive was investigated. The HDPE composite reinforced with 5% or 10%, by weight of Brazil nut shell fiber powder with particle sizes equal or smaller than 250 μm were obtained by extrusion, using a twin screw extruder. The materials were irradiated at 200 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated specimens tests samples were submitted to mechanical and thermo-mechanical tests, scanning electron microscopy (SEM), X-Ray diffraction (XRD) and sol-gel analysis and the correlation between their properties was discussed. The results showed significant changes in HDPE mechanical and thermo-mechanical properties due to Brazil nut shell fibers addition and electron-beam irradiation. The surface of the cryo fractured composite samples irradiated showed important visual changes which suggest a better fiber-matrix interfacial adhesion, due to irradiation treatment. These results showed that it is possible to get interesting property gains by using waste from renewable sources instead of the traditional ones and electron-beam radiation treatment. (author)

  14. Development of an anisotropic beam finite element for composite wind turbine blades in multibody system

    DEFF Research Database (Denmark)

    Kim, Taeseong; Hansen, Anders Melchior; Branner, Kim

    2013-01-01

    In this paper a new anisotropic beam finite element for composite wind turbine blades is developed and implemented into the aeroelastic nonlinear multibody code, HAWC2, intended to be used to investigate if use of anisotropic material layups in wind turbine blades can be tailored for improved...

  15. Fabrication of WCp/NiBSi metal matrix composite by electron beam melting

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Hui, E-mail: penghui@buaa.edu.cn [School of Materials Science and Engineering, Beihang University (BUAA), No. 37 Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials & Performance (Ministry of Education), Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China); Liu, Chang [School of Materials Science and Engineering, Beihang University (BUAA), No. 37 Xueyuan Road, Beijing 100191 (China); Guo, Hongbo, E-mail: guo.hongbo@buaa.edu.cn [School of Materials Science and Engineering, Beihang University (BUAA), No. 37 Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials & Performance (Ministry of Education), Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China); Yuan, Yuan [Zhuzhou Seed Cemented Carbide Technology Co. Ltd, No. 1099 Xiangda Road, Zhuzhou, Hunan 412000 (China); Gong, Shengkai; Xu, Huibin [School of Materials Science and Engineering, Beihang University (BUAA), No. 37 Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials & Performance (Ministry of Education), Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China)

    2016-06-01

    A blend of NiBSi and WC powders was used as raw material for fabricating a metal matrix composite (MMC) by electron beam melting (EBM). Dense and crack-free microstructure was produced with evenly distributed WC reinforcements. Mechanical properties, including macro- and micro-hardness, flexural strength, impact toughness and compressive strength, were investigated.

  16. Effects of electron-beam irradiation on HDPE/Brazil nut shell fiber composite

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Maiara S.; Sartori, Mariana N.; Oliveira, Rene R.; Moura, Esperidiana A.B., E-mail: maiara.sferreira@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    In recent years, research on the replacement of synthetic fibers by natural fibers as reinforcement in thermoplastic composites has increased dramatically due to the advantages of natural fibers, such as low density, low cost, environmental appeal and recyclability. In the present work, the influence of electron-beam irradiation on mechanical properties of HDPE and HDPE/Brazil Nut Shell (Bertholletia excelsa) fiber compositive was investigated. The HDPE composite reinforced with 5% or 10%, by weight of Brazil nut shell fiber powder with particle sizes equal or smaller than 250 μm were obtained by extrusion, using a twin screw extruder. The materials were irradiated at 200 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated specimens tests samples were submitted to mechanical and thermo-mechanical tests, scanning electron microscopy (SEM), X-Ray diffraction (XRD) and sol-gel analysis and the correlation between their properties was discussed. The results showed significant changes in HDPE mechanical and thermo-mechanical properties due to Brazil nut shell fibers addition and electron-beam irradiation. The surface of the cryo fractured composite samples irradiated showed important visual changes which suggest a better fiber-matrix interfacial adhesion, due to irradiation treatment. These results showed that it is possible to get interesting property gains by using waste from renewable sources instead of the traditional ones and electron-beam radiation treatment. (author)

  17. Fabrication of WCp/NiBSi metal matrix composite by electron beam melting

    International Nuclear Information System (INIS)

    Peng, Hui; Liu, Chang; Guo, Hongbo; Yuan, Yuan; Gong, Shengkai; Xu, Huibin

    2016-01-01

    A blend of NiBSi and WC powders was used as raw material for fabricating a metal matrix composite (MMC) by electron beam melting (EBM). Dense and crack-free microstructure was produced with evenly distributed WC reinforcements. Mechanical properties, including macro- and micro-hardness, flexural strength, impact toughness and compressive strength, were investigated.

  18. Investigation on Failures of Composite Beam and Substrate Concrete due to Drying Shrinkage Property of Repair Materials

    Science.gov (United States)

    Pattnaik, Rashmi Ranjan

    2017-06-01

    A Finite Element Analysis (FEA) and an experimental study was conducted on composite beam of repair material and substrate concrete to investigate the failures of the composite beam due to drying shrinkage property of the repair materials. In FEA, the stress distribution in the composite beam due to two concentrate load and shrinkage of repair materials were investigated in addition to the deflected shape of the composite beam. The stress distributions and load deflection shapes of the finite element model were investigated to aid in analysis of the experimental findings. In the experimental findings, the mechanical properties such as compressive strength, split tensile strength, flexural strength, and load-deflection curves were studied in addition to slant shear bond strength, drying shrinkage and failure patterns of the composite beam specimens. Flexure test was conducted to simulate tensile stress at the interface between the repair material and substrate concrete. The results of FEA were used to analyze the experimental results. It was observed that the repair materials with low drying shrinkage are showing compatible failure in the flexure test of the composite beam and deform adequately in the load deflection curves. Also, the flexural strength of the composite beam with low drying shrinkage repair materials showed higher flexural strength as compared to the composite beams with higher drying shrinkage value of the repair materials even though the strength of those materials were more.

  19. In vitro comparative study of share bond of light cured composite resins with halogen light and argon laser, using stainless steel brackets on human premolars

    International Nuclear Information System (INIS)

    Carillo, Vitoria Eugenia Bismarck

    2004-01-01

    The aim of this study in vitro was to compare the share bond strength of the light-cured composite resins Transbond XT (Unitek), with halogen light and argon laser. The Adhesive Remmant Index (ARI) was also investigated. The brackets Dyna lock (3M-UNITEK) were bonded to 75 human premolars, divided into 5 groups (15 each) according to time and the polymerization: Group H20, 15 brackets bonded with halogen light for 20s (10s both sides); Group H40, 15 brackets bonded with halogen light for 40s (20s both sides); Group A40, 15 brackets bonded with argon laser for 40s (20s both sides); Group A20, 15 brackets bonded with argon laser for 20s (10s both sides); Group A10, 15 brackets bonded with argon laser for 10s (5s both sides). The pulpal temperature changes were determined during a polymerization, not exceeding 3,5 deg C. After bonding, the teeth were submitted to a thermo cycled of 700 cycles between 5 deg C and 55 deg C, to simulate the consuming that the light cured composite resin would have in a short space of time. The specimens were then placed in PVC ring and embedded in acrylic resin (Aero-Jet). The tensile bond strength test was performed on an Universal Machine set at a crosshead speed of 1,5 mm/min, and for each rupture we registered a graphic and the best load required in Newtons, was converted to MPa and kgf. The share bond strength showed bigger values for the exposure time of 20 seconds, for the Group bonded for halogen light (H20), 7,45 kgf (7,64 MPa) and for argon laser 7,50 kgf (7,69 MPa); lesser values for the exposure time of 40s for the Group with halogen light (H40), 6,15 kgf (6,30 MPa) and argon laser Group (A40), 6,20 kgf (6,35 MPa) 0; and A10, 4,85 kgf (4,97 MPa). In the ARI Index, only A40 Group showed the 1 Index, with statistical results. In this Group, less than half of the remainder adhesive stayed on the surface of the enamel, conferring specimens failed at the enamel-adhesive interface. The results of the in vitro study demonstrate that

  20. Buckling behavior of fiber reinforced plastic–metal hybrid-composite beam

    International Nuclear Information System (INIS)

    Eksi, Secil; Kapti, Akin O.; Genel, Kenan

    2013-01-01

    Highlights: ► We developed a new plastic–metal hybrid-composite tubular beam structure. ► This structure offers innovative design solutions with weight reduction. ► It prevents premature buckling without adding significant weight to the structure. ► The composite interaction gives better mechanical properties to the products. ► Buckling and bending loads of the beam increased 3.2 and 7.6 times, respectively. - Abstract: It is known that the buckling is characterized by a sudden failure of a structural member subjected to high compressive load. In this study, the buckling behavior of the aluminum tubular beam (ATB) was analyzed using finite element (FE) method, and the reinforcing arrangements as well as its combinations were decided for the composite beams based on the FE results. Buckling and bending behaviors of thin-walled ATBs with internal cast polyamide (PA6) and external glass and carbon fiber reinforcement polymers (GFRPs and CFRPs) were investigated systematically. Experimental studies showed that the 219% increase in buckling load and 661% in bending load were obtained with reinforcements. The use of plastics and metal together as a reinforced structure yields better mechanical performance properties such as high resistance to buckling and bending loads, dimensional stability and high energy absorption capacity, including weight reduction. While the thin-walled metallic component provides required strength and stiffness, the plastic component provides the support necessary to prevent premature buckling without adding significant weight to the structure. It is thought that the combination of these materials will offer a promising new focus of attention for designers seeking more appropriate composite beams with high buckling loads beside light weight. The developed plastic–metal hybrid-composite structure is promising especially for critical parts serving as a support member of vehicles for which light weight is a critical design

  1. Compression of laminated composite beams with initial damage

    Science.gov (United States)

    Breivik, Nicole L.; Gurdal, Zafer; Griffin, O. H., Jr.

    1993-01-01

    The effect of isolated damage modes on the compressive strength and failure characteristics of laminated composite test specimens were evaluated experimentally and numerically. In addition to specimens without initial damage, specimens with three types of initial damage were considered: (1) specimens with short delaminations distributed evenly through the specimen thickness, (2) specimens with few long delaminations, and (3) specimens with local fiber damage in the surface plies under the three-point bend contact point. It was found that specimens with short multiple delamination experienced the greatest reduction in compression strength compared to the undamaged specimens. Single delaminations far from the specimen surface had little effect on the final compression strength, and moderate strength reduction was observed for specimens with localized surface ply damage.

  2. Proceedings of workshop on surface finishing by radiation curing technology: radiation curing for better finishing

    International Nuclear Information System (INIS)

    1993-01-01

    This book compiled the paper presented at this workshop. The papers discussed are 1. Introduction to radiation curing, 2. Radiation sources -ultraviolet and electron beams, 3. UV/EB curing of surface coating - wood and nonwood substrates, 4. Development of EPOLA (epoxidised palm oil products acrylate) and its application, 5. Development of radiation-curable resin based natural rubber

  3. Proceedings of workshop on surface finishing by radiation curing technology: radiation curing for better finishing

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    This book compiled the paper presented at this workshop. The papers discussed are 1. Introduction to radiation curing, 2. Radiation sources -ultraviolet and electron beams, 3. UV/EB curing of surface coating - wood and nonwood substrates, 4. Development of EPOLA (epoxidised palm oil products acrylate) and its application, 5. Development of radiation-curable resin based natural rubber.

  4. Effect of Electrospun Nanofibers on the Short Beam Strength of Laminated Fiberglass Composite

    Science.gov (United States)

    Shinde, Dattaji K.

    High specific modulus and strength are the most desirable properties for the material used in structural applications. Composite materials exhibit these properties and over the last decade, their usage has increased significantly, particularly in automotive, defense, and aerospace applications. The major cause of failures in composite laminates is due to delaminations. Delamination in composite laminates can occur due to fatigue, low velocity impact and other loadings modes. Conventional methods like "through-the-thickness stitching" or "Z-Pinning" have limitations for improving flexural and interlaminar properties in woven composites due to the fact that while improving interlaminar properties, the presence of stitches or Z pins affects in-plane properties. This study investigates the flexural behavior of fiberglass composites interleaved with non-woven Tetra Ethyl Orthosilicate (TEOS) electrsopsun nanofibers (ENFs). TEOS ENFs were manufactured using an electrospinning technique and then sintered. Nanoengineered beams were fabricated by interleaving TEOS ENFs between the laminated fiberglass composites to improve the flexural properties. TEOS ENFs, resin film, and failed fiberglass laminated composites with and without nanofibers were characterized using SEM Imaging and ASTM standard testing methods. A hybrid composite was made by interleaving a non-woven sheet of TEOS ENFs between the fiberglass laminates with additional epoxy resin film and fabricated using the out of autoclave vacuum bagging method. Four commonly used stacking sequences of fiberglass laminates with and without nanofibers were used to study the progressive failure and deformation mechanics under flexural loadings. The experimental study has shown significant improvements in short beam strength and strain energy absorption in the nanoengineered laminated fiberglass composites before complete failure. The modes were investigated by performing detailed fractographic examination of failed specimens

  5. An electro-mechanical impedance model of a cracked composite beam with adhesively bonded piezoelectric patches

    Science.gov (United States)

    Yan, Wei; Cai, J. B.; Chen, W. Q.

    2011-01-01

    A model of a laminated composite beam including multiple non-propagating part-through surface cracks as well as installed PZT transducers is presented based on the method of reverberation-ray matrix (MRRM) in this paper. Toward determining the local flexibility characteristics induced by the individual cracks, the concept of the massless rotational spring is applied. A Timoshenko beam theory is then used to simulate the behavior of the composite beam with open cracks. As a result, transverse shear and rotatory inertia effects are included in the model. Only one-dimensional axial vibration of the PZT wafer is considered and the imperfect interfacial bonding between PZT patches and the host beam is further investigated based on a Kelvin-type viscoelastic model. Then, an accurate electro-mechanical impedance (EMI) model can be established for crack detection in laminated beams. In this model, the effects of various parameters such as the ply-angle, fibre volume fraction, crack depth and position on the EMI signatures are highlighted. Furthermore, comparison with existent numerical results is presented to validate the present analysis.

  6. Nonlinear finite element modeling of concrete deep beams with openings strengthened with externally-bonded composites

    International Nuclear Information System (INIS)

    Hawileh, Rami A.; El-Maaddawy, Tamer A.; Naser, Mohannad Z.

    2012-01-01

    Highlights: ► A 3D nonlinear FE model is developed of RC deep beams with web openings. ► We used cohesion elements to simulate bond. ► The developed FE model is suitable for analysis of such complex structures. -- Abstract: This paper aims to develop 3D nonlinear finite element (FE) models for reinforced concrete (RC) deep beams containing web openings and strengthened in shear with carbon fiber reinforced polymer (CFRP) composite sheets. The web openings interrupted the natural load path either fully or partially. The FE models adopted realistic materials constitutive laws that account for the nonlinear behavior of materials. In the FE models, solid elements for concrete, multi-layer shell elements for CFRP and link elements for steel reinforcement were used to simulate the physical models. Special interface elements were implemented in the FE models to simulate the interfacial bond behavior between the concrete and CFRP composites. A comparison between the FE results and experimental data published in the literature demonstrated the validity of the computational models in capturing the structural response for both unstrengthened and CFRP-strengthened deep beams with openings. The developed FE models can serve as a numerical platform for performance prediction of RC deep beams with openings strengthened in shear with CFRP composites.

  7. Frequency and deflection analysis of cenosphere/glass fiber interply hybrid composite cantilever beam

    Science.gov (United States)

    Bharath, J.; Joladarashi, Sharnappa; Biradar, Srikumar; Kumar, P. Naveen

    2018-04-01

    Interply hybrid laminates contain plies made of two or more different composite systems. Hybrid composites have unique features that can be used to meet specified design requirements in a more cost-effective way than nonhybrid composites. They offer many advantages over conventional composites including balanced strength and stiffness, enhanced bending and membrane mechanical properties, balanced thermal distortion stability, improved fatigue/impact resistance, improved fracture toughness and crack arresting properties, reduced weight and cost. In this paper an interply hybrid laminate composite containing Cenosphere reinforced polymer composite core and glass fiber reinforced polymer composite skin is analysied and effect of volume fraction of filler on frequency and load v/s deflection of hybrid composite are studied. Cenosphere reinforced polymer composite has increased specific strength, specific stiffness, specific density, savings in cost and weight. Glass fiber reinforced polymer composite has higher torsional rigidity when compared to metals. These laminate composites are fabricated to meet several structural applications and hence there is a need to study their vibration and deflection properties. Experimental investigation starts with fabrication of interply hybrid composite with cores of cenosphere reinforced epoxy composite volume fractions of CE 15, CE 25, CE15_UC as per ASTM E756-05C, and glasss fiber reinforced epoxy skin, cast product of required dimension by selecting glass fibre of proper thickness which is currently 0.25mm E-glass bidirectional woven glass fabric having density 2500kg/m3, in standard from cast parts of size 230mmX230mmX5mm in an Aluminum mould. Modal analysis of cantilever beam is performed to study the variation of natural frequency with strain gauge and the commercially available Lab-VIEW software and deflection in each of the cases by optical Laser Displacement Measurement Sensor to perform Load versus Deflection Analysis

  8. Multi-axial load application and DIC measurement of advanced composite beam deformation behavior

    Directory of Open Access Journals (Sweden)

    Berggreen C.

    2010-06-01

    Full Text Available For the validation of a new beam element formulation, a wide set of experimental data consisting of deformation patterns obtained for a number of specially designed composite beam elements, have been obtained. The composite materials applied in the beams consist of glass-fiber reinforced plastic with specially designed layup configurations promoting advanced coupling behavior. Furthermore, the beams are designed with different cross-section shapes. The data obtained from the experiments are also used in order to improve the general understanding related to practical implementation of mechanisms of elastic couplings due to anisotropic properties of composite materials. The knowledge gained from these experiments is therefore essential in order to facilitate an implementation of passive control in future large wind turbine blades. A test setup based on a four-column MTS servo-hydraulic testing machine with a maximum capacity of 100 kN was developed, see Figure 1. The setup allows installing and testing beams of different cross-sections applying load cases such as axial extension, shear force bending, pure bending in two principal directions as well as pure torsion, see Figure 2. In order to apply multi-axial loading, a load application system consisting of three hydraulic actuators were mounted in two planes using multi-axial servo-hydraulic control. The actuator setup consists of the main actuator on the servo-hydraulic test machine working in the vertical axis (depicted on Figure 1 placed at the testing machine crosshead and used for application of vertical forces to the specimens. Two extra actuators are placed in a horizontal plane on the T-slot table of the test machine in different positions in order to apply loading at the tip of the specimen in various configurations. In order to precisely characterize the global as well as surface deformations of the beam specimens tested, a combination of different measurement systems were used during

  9. Composite model describing the excitation and de-excitation of nitrogen by an electron beam

    International Nuclear Information System (INIS)

    Kassem, A.E.; Hickman, R.S.

    1975-01-01

    Based on recent studies, the effect of re-excited ions in the emission of electron beam induced fluorescence in nitrogen has been estimated. These effects are included in the formulation of a composite model describing the excitation and de-excitation of nitrogen by an electron beam. The shortcomings of previous models, namely the dependence of the measured temperature on true gas temperature as well as the gas density, are almost completely eliminated in the range of temperatures and densities covered by the available data. (auth)

  10. Concept selection of car bumper beam with developed hybrid bio-composite material

    International Nuclear Information System (INIS)

    Davoodi, M.M.; Sapuan, S.M.; Ahmad, D.; Aidy, A.; Khalina, A.; Jonoobi, Mehdi

    2011-01-01

    Highlights: → We simulate the low impact test by Abaqus Ver16R9 using the same material model. → Six different weighted criteria were discussed to nominate the best concept. → Double Hat Profile showed the best concept to fulfil the defined PDS. → Geometric parameters may overcome the weak inherent properties of bio composite. → Toughened bio-composite material may employ in structural automotive components. -- Abstract: Application of natural fibre composites is going to increase in different areas caused by environmental, technical and economic advantages. However, their low mechanical properties have limited their particular application in automotive structural components. Hybridizations with other reinforcements or matrices can improve mechanical properties of natural fibre composite. Moreover, geometric optimizations have a significant role in structural strength improvement. This study focused on selecting the best geometrical bumper beam concept to fulfill the safety parameters of the defined product design specification (PDS). The mechanical properties of developed hybrid composite material were considered in different bumper beam concepts with the same frontal curvature, thickness, and overall dimensions. The low-speed impact test was simulated under the same conditions in Abaqus V16R9 software. Six weighted criteria, which were deflection, strain energy, mass, cost, easy manufacturing, and the rib possibility were analyzed to form an evaluation matrix. Topsis method was employed to select the best concept. It is concluded that double hat profile (DHP) with defined material model can be used for bumper beam of a small car. In addition, selected concept can be strengthened by adding reinforced ribs or increasing the thickness of the bumper beam to comply with the defined PDS.

  11. Compositional changes in industrial hemp biomass (Cannabis sativa L.) induced by electron beam irradiation Pretreatment

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Yong Joo [Department of Biobased Materials, College of Agriculture and Life Science, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Shin, Soo-Jeong [Department of Wood and Paper Science, College of Agriculture and Life Science, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)

    2011-07-15

    The effects of electron beam irradiation on chemical decomposition of industrial hemp biomass were evaluated at doses of 150, 300, and 450 kGy. The quantity of decomposed components was indirectly estimated by measuring changes in alkaline extraction. The more severe degradation of structural components induced by higher irradiation doses resulted in larger amounts of alkaline extract. Carbohydrate compositional analysis using {sup 1}H-NMR spectroscopy was applied to quantitatively investigate changes in the polysaccharides of the industrial hemp. The xylose peak intensity in the NMR spectra decreased with increasing electron irradiation dose, indicating that xylan was more sensitive to electron beam irradiation than cellulose. -- Highlights: {yields} The more severe degradation of structural components induced by higher irradiation. {yields} Carbohydrate analysis was applied to quantitatively investigate changes in the industrial hemp. {yields} Xylan was more sensitive to electron beam irradiation than cellulose.

  12. Compositional changes in industrial hemp biomass (Cannabis sativa L.) induced by electron beam irradiation Pretreatment

    International Nuclear Information System (INIS)

    Sung, Yong Joo; Shin, Soo-Jeong

    2011-01-01

    The effects of electron beam irradiation on chemical decomposition of industrial hemp biomass were evaluated at doses of 150, 300, and 450 kGy. The quantity of decomposed components was indirectly estimated by measuring changes in alkaline extraction. The more severe degradation of structural components induced by higher irradiation doses resulted in larger amounts of alkaline extract. Carbohydrate compositional analysis using 1 H-NMR spectroscopy was applied to quantitatively investigate changes in the polysaccharides of the industrial hemp. The xylose peak intensity in the NMR spectra decreased with increasing electron irradiation dose, indicating that xylan was more sensitive to electron beam irradiation than cellulose. -- Highlights: → The more severe degradation of structural components induced by higher irradiation. → Carbohydrate analysis was applied to quantitatively investigate changes in the industrial hemp. → Xylan was more sensitive to electron beam irradiation than cellulose.

  13. Dynamic analysis of composite beam with piezoelectric layers under thermo-mechanical load

    Science.gov (United States)

    Toudehdehghan, A.; Rahman, M. M.; Nagi, Farrukh

    2017-10-01

    In this paper, the control of composite beam vibrations with sensor and actuator connected layers is considered with consideration of the effect of thermal environment. The coupling relation between electrical field and mechanical deformation with uncoupled thermal impact are used. The mathematical model of shear deformation (Timoshenko’s theory) has been applied and basic equations for piezoelectric sensors and actuators have been proposed. The equation of motion for the beam structure is obtained by the Hamilton principle and analyzed by finite element method. The control algorithm is based on proportional velocity control. Hence, the purpose of this article is to investigate the direct and inverse effects of piezoelectric on control of simply supported beam vibration under uniform temperature.

  14. FLEXURAL TESTING OF WOOD-CONCRETE COMPOSITE BEAM MADE FROM KAMPER AND BANGKIRAI WOOD

    Directory of Open Access Journals (Sweden)

    Fengky Satria Yoresta

    2015-07-01

    Full Text Available Certain wood has a tensile strength that almost equal with steel rebar in reinforced concrete beams. This research aims to understand the capacity and flexural behavior of concrete beams reinforced by wood (wood-concrete composite beam. Two different types of beams based on placement positions of wood layers are proposed in this study. Two kinds of wood used are consisted of Bangkirai (Shorea laevifolia and Kamper (Cinnamomum camphora, meanwhile the concrete mix ratio for all beams is 1 cement : 2 fine aggregates : 3 coarse aggregates. Bending test is conducted by using one-point loading method. The results show that composite beam using Bangkirai wood is stronger than beams using Kamper wood. More thicker wood layer in tensile area will increase the flexural strength of beams. Crack patterns identified could be classified into flexural cracks, shear cracks, and split on wood layer   Beberapa jenis kayu tertentu memiliki kekuatan tarik yang hampir sama dengan tulangan baja pada balok beton bertulang. Penelitian ini bertujuan memahami kapasitas dan perilaku lentur balok beton bertulang yang diperkuat menggunakan kayu (balok komposit beton-kayu. Dua tipe balok yang berbeda berdasarkan posisi penempatan kayu digunakan dalam penelitian ini. Dua jenis kayu yang digunakan adalah kayu Bangkirai (Shorea laevifolia and Kamper (Cinnamomum camphora, sementara itu rasio campuran beton untuk semua balok menggunakan perbandingan 1 semen : 2 agregat halus : 3 agregat kasar. Pengujian lentur dilakukan menggunakan metode one-point loading. Hasil penelitian menunjukkan bahwa balok komposit dengan kayu Bangkirai lebih kuat dibandingkan balok dengan kayu Kamper. Semakin tebal lapisan kayu yang berada di daerah tarik akan meningkatkan kekuatan lentur balok. Pola kerusakan yang teridentifikasi dapat diklasifikasikan menjadi retak lentur, retak geser, dan pecah pada kayu REFERENCES Boen T. (2010. Retrofitting Simple Buildings Damaged by Earthquakes. World Seismic

  15. Digital-image-correlation-based experimental stress analysis of reinforced concrete beams strengthened using carbon composites

    Science.gov (United States)

    Helm, Jeffrey; Kurtz, Stephen

    2005-01-01

    The strengthening of reinforced concrete beams through the use of epoxy-bonded carbon composites has been widely researched in the United States since 1991. Despite the widespread attention of researchers, however, there are no reliable methods of predicting the failure of the repaired and strengthened beams by peeling of the fiber reinforced polymer (FRP) material from the parent concrete. To better understand peeling failure, several investigators have presented analytical work to predict the distribution of stresses along the interface between the FRP and the concrete. Several closed-form solutions can be found in the literature to predict the levels of shear stress present between the bonded composite plate and the parent concrete beam. However, there has been very little experimental verification of these analytical predictions because few experiments on large-scale beams have had sufficient instrumentation to facilitate the comparison. Some experiments have been presented1 in which electrical resistance strain gages were placed along the length of the carbon plate in order to deduce the interfacial shear stress using first differences. This method, though very crude, demonstrated that there are substantial differences between the distributions of interfacial shear stresses in actual repaired beams versus the analytical predictions. This paper presents a new test program in which large-scale carbon-fiber-strengthened reinforced concrete beams are load-tested to failure, while employing digital image correlation (DIC) to record the strains in the carbon fiber plate. Relying on the linear elasticity of carbon fiber, the interfacial shear can be determined and compared with the analytical predictions of the literature. The focus of this paper is the presentation of the experimental shear stress distributions and comparisons of these distributions with previous results available in the literature.

  16. The analysis of composite laminated beams using a 2D interpolating meshless technique

    Science.gov (United States)

    Sadek, S. H. M.; Belinha, J.; Parente, M. P. L.; Natal Jorge, R. M.; de Sá, J. M. A. César; Ferreira, A. J. M.

    2018-02-01

    Laminated composite materials are widely implemented in several engineering constructions. For its relative light weight, these materials are suitable for aerospace, military, marine, and automotive structural applications. To obtain safe and economical structures, the modelling analysis accuracy is highly relevant. Since meshless methods in the recent years achieved a remarkable progress in computational mechanics, the present work uses one of the most flexible and stable interpolation meshless technique available in the literature—the Radial Point Interpolation Method (RPIM). Here, a 2D approach is considered to numerically analyse composite laminated beams. Both the meshless formulation and the equilibrium equations ruling the studied physical phenomenon are presented with detail. Several benchmark beam examples are studied and the results are compared with exact solutions available in the literature and the results obtained from a commercial finite element software. The results show the efficiency and accuracy of the proposed numeric technique.

  17. Meshless Solution of the Problem on the Static Behavior of Thin and Thick Laminated Composite Beams

    Science.gov (United States)

    Xiang, S.; Kang, G. W.

    2018-03-01

    For the first time, the static behavior of laminated composite beams is analyzed using the meshless collocation method based on a thin-plate-spline radial basis function. In the approximation of a partial differential equation by using a radial basis function, the shape parameter has an important role in ensuring the numerical accuracy. The choice of a shape parameter in the thin plate spline radial basis function is easier than in other radial basis functions. The governing differential equations are derived based on Reddy's third-order shear deformation theory. Numerical results are obtained for symmetric cross-ply laminated composite beams with simple-simple and cantilever boundary conditions under a uniform load. The results found are compared with available published ones and demonstrate the accuracy of the present method.

  18. Dynamic behavior of three-dimensional composite beam under flapwise excitation

    Energy Technology Data Exchange (ETDEWEB)

    Eftekhari, Mojtaba [Dept. of Mechanical Engineering, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

    2016-08-15

    In this paper, dynamic response of a symmetrically laminated composite beam is studied under harmonic base excitation. The base is subjected to flapwise excitation tuned to the primary resonance in the presence of 2:1 internal resonance between the out-of-plane bending motion and the in-plane bending and torsional motions. In literature, modified modulation equations of composite beam have been derived and the stability of fixed points has been investigated in frequency and forced responses. However, post-critical behavior of the modulation equations is studied in this study. In bifurcation diagrams sketched near primary and internal resonances, it appears that detuning the flapwise excitation amplitude causes phenomena like jumps, period doubling, multi and quasi-periodic solutions to occur.

  19. POLYMER COMPOSITE FILMS WITH SIZE-SELECTED METAL NANOPARTICLES FABRICATED BY CLUSTER BEAM TECHNIQUE

    DEFF Research Database (Denmark)

    Ceynowa, F. A.; Chirumamilla, Manohar; Popok, Vladimir

    2017-01-01

    Formation of polymer films with size-selected silver and copper nanoparticles (NPs) is studied. Polymers are prepared by spin coating while NPs are fabricated and deposited utilizing a magnetron sputtering cluster apparatus. The particle embedding into the films is provided by thermal annealing...... after the deposition. The degree of immersion can be controlled by the annealing temperature and time. Together with control of cluster coverage the described approach represents an efficient method for the synthesis of thin polymer composite layers with either partially or fully embedded metal NPs....... Combining electron beam lithography, cluster beam deposition and thermal annealing allows to form ordered arrays of metal NPs on polymer films. Plasticity and flexibility of polymer host and specific properties added by coinage metal NPs open a way for different applications of such composite materials...

  20. New Green Polymeric Composites Based on Hemp and Natural Rubber Processed by Electron Beam Irradiation

    Directory of Open Access Journals (Sweden)

    Maria-Daniela Stelescu

    2014-01-01

    Full Text Available A new polymeric composite based on natural rubber reinforced with hemp has been processed by electron beam irradiation and characterized by several methods. The mechanical characteristics: gel fraction, crosslink density, water uptake, swelling parameters, and FTIR of natural rubber/hemp fiber composites have been investigated as a function of the hemp content and absorbed dose. Physical and mechanical properties present a significant improvement as a result of adding hemp fibres in blends. Our experiments showed that the hemp fibers have a reinforcing effect on natural rubber similar to mineral fillers (chalk, carbon black, silica. The crosslinking rates of samples, measured using the Flory-Rehner equation, increase as a result of the amount of hemp in blends and the electron beam irradiation dose increasing. The swelling parameters of samples significantly depend on the amount of hemp in blends, because the latter have hydrophilic characteristics.

  1. NONA Cure of Prepreg Structures, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — CRG's no-oven, no-autoclave (NONA) cure of OoA or autoclave prepreg materials allows the manufacture of large composite structures without the expensive and...

  2. Physicochemical Study of Irradiated polypropylene/Organo :Modified Montmorillonite Composites by Using Electron Beam Irradiation Technique

    International Nuclear Information System (INIS)

    Hassan, M.S.

    2008-01-01

    Polypropylene/ Organo modified montmorillonite composites (PP/ OMMT) were prepared by melt blending with a twin screw extruder. The thermal properties by thermo gravimetric analysis (TGA), the dispersion of OMMT of macromolecules by X-ray diffraction (XRD), mechanical properties and the morphology by scanning electron microscopy (SEM) were investigated. The effect of electron beam irradiation on these properties was also studied. The results showed an intercalation between the silicate layers and the PP polymer matrix. The (PP/ OMMT) composites exhibit higher thermal stability and lower mechanical properties than pure polypropylene

  3. Reduction of space charge breakdown in e-beam irradiated nano/polymethyl methacrylate composites

    International Nuclear Information System (INIS)

    Zheng Feihu; Zhang Yewen; An Zhenlian; Dong Jianxing; Lei Qingquan

    2013-01-01

    Fast discharge of numerous space charges in dielectric materials can cause space charge breakdown. This letter reports the role of nanoparticles in affecting space charge breakdown of nano/polymethyl methacrylate composites. Space charge distributions in the composites, implanted by electron beam irradiation, were measured by pressure wave propagation method. The results show that the nanoparticles have significant effects on the isothermal charge decay and space charge breakdown in the nanocomposites. The resistance to space charge breakdown in the nanocomposites is attributed to the combined action of the introduction of deep trapping states and the scattering effect by the added nanoparticles.

  4. EB/UV curing market in Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    Dahlan, Khairul Zaman; Nik Salleh, Nik Ghazali; Mahmood, Mohd Hilmi [Malaysian Inst. for Nuclear Technology Res. (MINT), Bangi (Malaysia)

    1999-07-01

    Radiation curing of coatings of wood based products is expanding and being used for curing of coatings of table tops, parquet, wood panel, furniture, curtain railing, etc. UV curing of over print varnish is still the main application of UV curing in printing industry. However, curing ofprinting ink has also been extended in the printing of CD and VCD in addition to other printing such as paper, magazine, label on bottles, metal-can, etc. In the electronic industry, the manufacturer of printed circuit board is still the main consumer of UV curable resins. On the other hand, low energy electron beam machine is used mainly for cross-linking of heat shrink films.

  5. EB/UV curing market in Malaysia

    International Nuclear Information System (INIS)

    Khairul Zaman Dahlan; Nik Ghazali Nik Salleh; Mohd Hilmi Mahmood

    1999-01-01

    Radiation curing of coatings of wood based products is expanding and being used for curing of coatings of table tops, parquet, wood panel, furniture, curtain railing, etc. UV curing of over print varnish is still the main application of UV curing in printing industry. However, curing of printing ink has also been extended in the printing of CD and VCD in addition to other printing such as paper, magazine, label on bottles, metal-can, etc. In the electronic industry, the manufacturer of printed circuit board is still the main consumer of UV curable resins. On the other hand, low energy electron beam machine is used mainly for cross-linking of heat shrink films

  6. Effect of electron beam irradiation on thermal and mechanical properties of aluminum based epoxy composites

    Science.gov (United States)

    Visakh, P. M.; Nazarenko, O. B.; Sarath Chandran, C.; Melnikova, T. V.; Nazarenko, S. Yu.; Kim, J.-C.

    2017-07-01

    The epoxy resins are widely used in nuclear and aerospace industries. The certain properties of epoxy resins as well as the resistance to radiation can be improved by the incorporation of different fillers. This study examines the effect of electron beam irradiation on the thermal and mechanical properties of the epoxy composites filled with aluminum nanoparticles at percentage of 0.35 wt%. The epoxy composites were exposed to the irradiation doses of 30, 100 and 300 kGy using electron beam generated by the linear electron accelerator ELU-4. The effects of the doses on thermal and mechanical properties of the aluminum based epoxy composites were investigated by the methods of thermal gravimetric analysis, tensile test, and dynamic mechanical analysis. The results revealed that the studied epoxy composites showed good radiation resistance. The thermal and mechanical properties of the aluminum based epoxy composites increased with increasing the irradiation dose up to 100 kGy and decreased with further increasing the dose.

  7. Active Vibration damping of Smart composite beams based on system identification technique

    Science.gov (United States)

    Bendine, Kouider; Satla, Zouaoui; Boukhoulda, Farouk Benallel; Nouari, Mohammed

    2018-03-01

    In the present paper, the active vibration control of a composite beam using piezoelectric actuator is investigated. The space state equation is determined using system identification technique based on the structure input output response provided by ANSYS APDL finite element package. The Linear Quadratic (LQG) control law is designed and integrated into ANSYS APDL to perform closed loop simulations. Numerical examples for different types of excitation loads are presented to test the efficiency and the accuracy of the proposed model.

  8. Influence of electron beam Irradiation on PP/Piassava fiber composite prepared by melt extrusion process

    International Nuclear Information System (INIS)

    Gomes, Michelle G.; Ferreira, Maiara S.; Oliveira, Rene R.; Silva, Valquiria A.; Teixeira, Jaciele G.; Moura, Esperidiana A.B.

    2013-01-01

    In the latest years, the interest for the use of natural fibers in materials composites polymeric has increased significantly due to their environmental and technological advantages. Piassava fibers (Attalea funifera) have been used as reinforcement in the matrix of thermoplastic and thermoset polymers. In the present work (20%, in mass), piassava fibers with particle sizes equal or smaller than 250 μm were incorporated in the polypropylene matrix (PP) no irradiated and polypropylene matrix containing 10 % and 30 % of polypropylene treated by electron-beam radiation at 40 kGy (PP/PPi/Piassava). The composites PP/Piassava and PP/PPi/Piassava were prepared by using a twin screw extruder, followed by injection molding. The composite material samples obtained were treated by electron-beam radiation at 40 kGy, using a 1.5 MeV electron beam accelerator, at room temperature, in presence of air. After irradiation treatment, the irradiated and non-irradiated specimens tests samples were submitted to thermo-mechanical tests, melt flow index (MFI), sol-gel analysis, X-Ray diffraction (XRD) and scanning electron microscopy (SEM). (author)

  9. Year of progress for radiation curing

    International Nuclear Information System (INIS)

    Mesrobian, R.B.

    1975-01-01

    New developments in ultraviolet and electron beam curing of inks and coatings are reviewed. Current installations of radiation systems are noted. An assessment is presented on raw and intermediate materials availability. Current outlook on such problems as toxicity (FDA and OSHA), residual volatiles, materials cost, adhesion and flow-out of coatings is discussed. The future potential for radiation curing systems is contrasted with that of other systems, in view of EPA requirements

  10. Radiation cured coatings for high performance products

    International Nuclear Information System (INIS)

    Parkins, J.C.; Teesdale, D.H.

    1984-01-01

    Development over the past ten years of radiation curable coating and lacquer systems and the means of curing them has led to new products in the packaging, flooring, furniture and other industries. Solventless lacquer systems formulated with acrylates and other resins enable high levels of durability, scuff resistance and gloss to be achieved. Ultra violet and electron beam radiation curing are used, the choice depending on the nature of the coating, the product and the scale of the operation. (author)

  11. Effect of carbon black composition with sludge palm oil on the curing characteristic and mechanical properties of natural rubber/styrene butadiene rubber compound

    Science.gov (United States)

    Mohamed, R.; Nurazzi, N. Mohd; Huzaifah, M.

    2017-07-01

    This study was conducted to investigate the possibility of utilizing sludge palm oil (SPO) as processing oil, with various amount of carbon black as its reinforcing filler, and its effects on the curing characteristics and mechanical properties of natural rubber/styrene butadiene rubber (NR/SBR) compound. Rubber compound with fixed 15 pphr of SPO loading, and different carbon black loading from 20 to 50 pphr, was prepared using two roll mills. The cure characteristics and mechanical tests that have been conducted are the scorch and cure time analysis, tensile strength and tear strength. Scorch time (ts5) and cure time (t90) of the compound increases with the increasing carbon black loading. The mechanical properties of NR/SBR compound viz. the tensile strength, modulus at 300% strain and tear strength were also improved by the increasing carbon black loading.

  12. Overview of UV and EB curing

    International Nuclear Information System (INIS)

    Garnett, J.L.

    2000-01-01

    Full text: UV and EB are complementary techniques in radiation curing. In the proposed paper, a brief review of both fields will be given. This will include principles of the process, the chemistry of the systems including monomers/oligomers/polymers used, additives required where necessary such as photoinitiators for UV, flow aids, adhesion promoters and the like. The types of equipment used in such processes will also be discussed including low energy electron beam utilisation and excimer curing. The advantages and disadvantages of both techniques will be examined. Mechanistic aspects of both curing systems will be discussed. Applications of the technology including developments in the banknote printing field will be summarised

  13. A study of composite beam with shape memory alloy arbitrarily embedded under thermal and mechanical loadings

    International Nuclear Information System (INIS)

    Zhang Yin; Zhao Yapu

    2007-01-01

    The constitutive relations and kinematic assumptions on the composite beam with shape memory alloy (SMA) arbitrarily embedded are discussed and the results related to the different kinematic assumptions are compared. As the approach of mechanics of materials is to study the composite beam with the SMA layer embedded, the kinematic assumption is vital. In this paper, we systematically study the kinematic assumptions influence on the composite beam deflection and vibration characteristics. Based on the different kinematic assumptions, the equations of equilibrium/motion are different. Here three widely used kinematic assumptions are presented and the equations of equilibrium/motion are derived accordingly. As the three kinematic assumptions change from the simple to the complex one, the governing equations evolve from the linear to the nonlinear ones. For the nonlinear equations of equilibrium, the numerical solution is obtained by using Galerkin discretization method and Newton-Rhapson iteration method. The analysis on the numerical difficulty of using Galerkin method on the post-buckling analysis is presented. For the post-buckling analysis, finite element method is applied to avoid the difficulty due to the singularity occurred in Galerkin method. The natural frequencies of the composite beam with the nonlinear governing equation, which are obtained by directly linearizing the equations and locally linearizing the equations around each equilibrium, are compared. The influences of the SMA layer thickness and the shift from neutral axis on the deflection, buckling and post-buckling are also investigated. This paper presents a very general way to treat thermo-mechanical properties of the composite beam with SMA arbitrarily embedded. The governing equations for each kinematic assumption consist of a third order and a fourth order differential equation with a total of seven boundary conditions. Some previous studies on the SMA layer either ignore the thermal constraint

  14. The Load-Bearing Capacity of Timber-Glass Composite I-Beams Made with Polyurethane Adhesives

    Science.gov (United States)

    Rodacki, Konrad

    2017-12-01

    This article discusses the issue of composite timber-glass I-beams, which are an interesting alternative for load-bearing beams of ceilings and roofs. The reasoning behind the use of timber-glass I-beams is the combination of the best features of both materials - this enables the creation of particularly safe beams with regard to structural stability and post-breakage load capacity. Due to the significant differences between the bonding surfaces of timber and glass, a study on the adhesion of various adhesives to both surfaces is presented at the beginning of the paper. After examination, two adhesives were selected for offering the best performance when used with composite beams. The beams were investigated using a four-point bending test under quasi-static loading.

  15. Measurement of breast tissue composition with dual energy cone-beam computed tomography: A postmortem study

    Energy Technology Data Exchange (ETDEWEB)

    Ding Huanjun; Ducote, Justin L.; Molloi, Sabee [Department of Radiological Sciences, University of California, Irvine, California 92697 (United States)

    2013-06-15

    Purpose: To investigate the feasibility of a three-material compositional measurement of water, lipid, and protein content of breast tissue with dual kVp cone-beam computed tomography (CT) for diagnostic purposes. Methods: Simulations were performed on a flat panel-based computed tomography system with a dual kVp technique in order to guide the selection of experimental acquisition parameters. The expected errors induced by using the proposed calibration materials were also estimated by simulation. Twenty pairs of postmortem breast samples were imaged with a flat-panel based dual kVp cone-beam CT system, followed by image-based material decomposition using calibration data obtained from a three-material phantom consisting of water, vegetable oil, and polyoxymethylene plastic. The tissue samples were then chemically decomposed into their respective water, lipid, and protein contents after imaging to allow direct comparison with data from dual energy decomposition. Results: Guided by results from simulation, the beam energies for the dual kVp cone-beam CT system were selected to be 50 and 120 kVp with the mean glandular dose divided equally between each exposure. The simulation also suggested that the use of polyoxymethylene as the calibration material for the measurement of pure protein may introduce an error of -11.0%. However, the tissue decomposition experiments, which employed a calibration phantom made out of water, oil, and polyoxymethylene, exhibited strong correlation with data from the chemical analysis. The average root-mean-square percentage error for water, lipid, and protein contents was 3.58% as compared with chemical analysis. Conclusions: The results of this study suggest that the water, lipid, and protein contents can be accurately measured using dual kVp cone-beam CT. The tissue compositional information may improve the sensitivity and specificity for breast cancer diagnosis.

  16. Strength and deformability of concrete beams reinforced by non-metallic fiber and composite rebar

    Science.gov (United States)

    Kudyakov, K. L.; Plevkov, V. S.; Nevskii, A. V.

    2015-01-01

    Production of durable and high-strength concrete structures with unique properties has always been crucial. Therefore special attention has been paid to non-metallic composite and fiber reinforcement. This article describes the experimental research of strength and deformability of concrete beams with dispersed and core fiber-based reinforcement. As composite reinforcement fiberglass reinforced plastic rods with diameters 6 mm and 10 mm are used. Carbon and basalt fibers are used as dispersed reinforcement. The developed experimental program includes designing and production of flexural structures with different parameters of dispersed fiber and composite rebar reinforcement. The preliminary testing of mechanical properties of these materials has shown their effectiveness. Structures underwent bending testing on a special bench by applying flexural static load up to complete destruction. During the tests vertical displacements were recorded, as well as value of actual load, slippage of rebars in concrete, crack formation. As a result of research were obtained structural failure and crack formation graphs, value of fracture load and maximum displacements of the beams at midspan. Analysis of experimental data showed the effectiveness of using dispersed reinforcement of concrete and the need for prestressing of fiberglass composite rebar.

  17. Radiation processing of carbon fiber-acrylated epoxy composites

    International Nuclear Information System (INIS)

    Singh, A.; Saunders, C.B.

    1992-01-01

    Advanced composites, specifically carbon fiber reinforced epoxies, are being used for a variety of demanding structural applications, primarily because of their high strength-to-weight and stiffness-to-weight ratios, corrosion resistance, and damage tolerance characteristics. For these composites the key advantages of using electron beam (EB), rather than thermal curing, are curing at ambient temperature, reduced curing times for individual components, improved resin stability, fewer volatiles, and better control of the profile of energy absorption. Epoxy compounds do, however, have to be modified to make them EB curable. The electron beam penetration limit, a function of beam energy, product density, and the thickness of any container required, must also be examined when considering EB processing. Research is being conducted to develop EB-curable carbon fiber-acrylated epoxy composites. The tensile properties of these laminates are comparable to those of thermally cured epoxy laminates. Research is continuing to develop suitable resin formulations and coupling agents to optimize the mechanical properties of EB-cured carbon fiber laminates. In this chapter the EB curing of epoxies, processing considerations, and typical properties of EB-cured carbon fiber-acrylated epoxy laminates are discussed. (orig.)

  18. Plastic coating on paper by electron beam irradiation

    International Nuclear Information System (INIS)

    Ametani, Kazuo; Tsuchiya, Mitsuaki; Sawai, Takeshi

    1984-01-01

    It has been known long since that the resin system of unsaturated polyester and vinylmonomer mixture cures by irradiation. Ford of USA for the first time industrialized the radiation curing reaction of resins for the coating of automobile parts. Thereafter, accompanying the development and technical advance of the low energy electron beam irradiation apparatus which is suitable to surface treatment such as coating and easy to handle and the development of resins, the electron beam curing method has become to be utilized for coating hardboard and wooden doors, coating automobile tire rims, adhering printing papers and others. The electron beam curing method has advantage such as energy conservation, resource saving and little pollution because solvent is not used, high production rate and small floor space. In glossing industry, for the purpose of developing the techniques to apply electron beam curing method to glazed paper production, the selection of the composition of resins suitable to glazed papers, the irradiating condition and the properties of cured films were examined. The films withstanding bending can be obtained at low dose with urethane group, ester group or the combination of monomers. (Kako, I.)

  19. Experimental investigation on ultimate strength and failure response of composite box beams used in wind turbine blades

    DEFF Research Database (Denmark)

    Tang, Jing; Chen, Xiao

    2018-01-01

    This study focuses on the ultimate strength and failure response of composite box beams under three-point bending. The box beams consist of spar caps and shear webs and they are typically used in wind turbine blades as load-carrying members. Different spar cap configurations and loading directions...

  20. Radiation curing of polymers

    International Nuclear Information System (INIS)

    Randell, D.R.

    1987-01-01

    The contents of this book are: Areas of Application of UV Curing; Areas of Application of EB Curing; Laser Curing of Acrylic Coatings; A User's View of the Application of Radiation Curable Materials; Radiation Curable Offset Inks: A Technical and Marketing Overview; and UV Curable Screen Printing Inks

  1. Experimental studies on active vibration control of a smart composite beam using a PID controller

    International Nuclear Information System (INIS)

    Jovanović, Miroslav M; Lukić, Nebojša S; Ilić, Slobodan S; Simonović, Aleksandar M; Zorić, Nemanja D; Stupar, Slobodan N

    2013-01-01

    This paper presents experimental verification of the active vibration control of a smart cantilever composite beam using a PID controller. In order to prevent negative occurrences in the derivative and integral terms in a PID controller, first-order low-pass filters are implemented in the derivative action and in the feedback of the integral action. The proposed application setup consists of a composite cantilever beam with a fiber-reinforced piezoelectric actuator and strain gage sensors. The beam is modeled using a finite element method based on third-order shear deformation theory. The experiment considers vibration control under periodic excitation and an initial static deflection. A control algorithm was implemented on a PIC32MX440F256H microcontroller. Experimental results corresponding to the proposed PID controller are compared with corresponding results using proportional (P) control, proportional–integral (PI) control and proportional–derivative (PD) control. Experimental results indicate that the proposed PID controller provides 8.93% more damping compared to a PD controller, 14.41% more damping compared to a PI controller and 19.04% more damping compared to a P controller in the case of vibration under periodic excitation. In the case of free vibration control, the proposed PID controller shows better performance (settling time 1.2 s) compared to the PD controller (settling time 1.5 s) and PI controller (settling time 2.5 s). (paper)

  2. Micro-Raman spectroscopic analysis of the degree of conversion of composite resins containing different initiators cured by polywave or monowave LED units.

    Science.gov (United States)

    Miletic, Vesna; Santini, Ario

    2012-02-01

    To determine the degree of conversion (DC) over 48 h post-curing of resin mixtures containing trimethylbenzoyl-diphenylphosphine oxide (TPO) initiator cured by a polywave or a monowave LED light-curing unit (LCU). In resin mixtures based on equal weight percent (wt%) of BisGMA and TEGDMA the following initiators were added: 0.2 wt% camphorquinone (CQ)+0.8 wt% ethyl-4-dimethylaminobenzoate (EDMAB) (Group 1); 1 wt% TPO (Group 2) and 0.1 wt% CQ+0.4 wt% EDMAB+0.5 wt% TPO (Group 3). Half of the samples in each group (n=5) were cured using a polywave (bluephase(®) G2, Ivoclar Vivadent) or a monowave LED LCU (bluephase(®), Ivoclar Vivadent). The DC was measured using micro-Raman spectroscopy within 5 min and then 1, 3, 6, 24 and 48 h post-irradiation. The data were analysed using general linear model and two-way ANOVA for the factors 'time', 'material', 'surface' and 'LCU' at α=0.05. The initial DC values obtained upon light curing remained similar over a 48 h period. bluephase(®) G2 produced the highest DC in Group 2 followed by Group 3, and Group 1. bluephase(®) resulted in the highest DC in Group 1, followed by Group 2 and Group 3 (pconversion of uncured monomers was detected in an unfilled resin material over 48 h at 37°C. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Report of the 1st RCM on Radiation Curing of Composites for Enhancing the Features and Utility in Health Care and Industry. Working Material

    International Nuclear Information System (INIS)

    2011-01-01

    Composite materials combine properties of the individual components in a synergetic manner to produce a variety of materials in an efficient and cost effective manner. Thus, composite materials today are being used in various applications from sports equipment, automotive and aerospace industries to food packaging and artificial organs. Materials reinforced with nanoscale components are adding new dimensions to composite materials and enable further major improvements in functional and structural properties. The incorporation of only a few percent of nano-sized particles can make dramatic property changes that may result in sensing, actualization or self-healing properties of the resulting composite. Several major issues need to be addressed to utilize the full potential of such nanofillers, and among them: (i) incompatibility or weak interfacial bonding between the matrix and the nanoscale component, and (ii) agglomeration of nanosized component during processing resulting in inhomogeneous distribution. According to the results of ongoing investigation and products preparation in several Member States institutions, radiation technology offers a way of overcoming these challenges by grafting of appropriate monomers/polymers onto the nanofiller surface thereby fixing their morphology and at the same time making them compatible with the host polymer. Additionally, radiation techniques offer the possibility for simultaneous synthesis of the nanoparticle component and crosslinking of the matrix of the composite that is not possible to achieve by other techniques. With the availability of lower cost self-shielded low energy electron beam accelerators, this process is increasingly becoming available for developing member states. In order to use the advantages of radiation techniques and address the needs of Member States for producing advanced composite materials, this CRP has been formulated based on the recommendations of the Consultant’s Meeting “meeting on

  4. Report of the 1st RCM on Radiation Curing of Composites for Enhancing the Features and Utility in Health Care and Industry. Working Material

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Composite materials combine properties of the individual components in a synergetic manner to produce a variety of materials in an efficient and cost effective manner. Thus, composite materials today are being used in various applications from sports equipment, automotive and aerospace industries to food packaging and artificial organs. Materials reinforced with nanoscale components are adding new dimensions to composite materials and enable further major improvements in functional and structural properties. The incorporation of only a few percent of nano-sized particles can make dramatic property changes that may result in sensing, actualization or self-healing properties of the resulting composite. Several major issues need to be addressed to utilize the full potential of such nanofillers, and among them: (i) incompatibility or weak interfacial bonding between the matrix and the nanoscale component, and (ii) agglomeration of nanosized component during processing resulting in inhomogeneous distribution. According to the results of ongoing investigation and products preparation in several Member States institutions, radiation technology offers a way of overcoming these challenges by grafting of appropriate monomers/polymers onto the nanofiller surface thereby fixing their morphology and at the same time making them compatible with the host polymer. Additionally, radiation techniques offer the possibility for simultaneous synthesis of the nanoparticle component and crosslinking of the matrix of the composite that is not possible to achieve by other techniques. With the availability of lower cost self-shielded low energy electron beam accelerators, this process is increasingly becoming available for developing member states. In order to use the advantages of radiation techniques and address the needs of Member States for producing advanced composite materials, this CRP has been formulated based on the recommendations of the Consultant’s Meeting “meeting on

  5. Effect of elemental composition of ion beam on the phase formation and surface strengthening of structural materials

    International Nuclear Information System (INIS)

    Avdienko, K.I.; Avdienko, A.A.; Kovalenko, I.A.

    2001-01-01

    The investigation results are reported on the influence of ion beam element composition on phase formation, wear resistance and microhardness of surface layers of titanium alloys VT-4 and VT-16 as well as stainless steel 12Kh18N10T implanted with nitrogen, oxygen and boron. It is stated that ion implantation into structural materials results in surface hardening and is directly dependent on element composition of implanted ion beam. The presence of oxygen in boron or nitrogen ion beams prevents the formation of boride and nitride phases thus decreasing a hardening effect [ru

  6. Numerical studies of shear damped composite beams using a constrained damping layer

    DEFF Research Database (Denmark)

    Kristensen, R.F.; Nielsen, Kim Lau; Mikkelsen, Lars Pilgaard

    2008-01-01

    Composite beams containing one or more damping layers are studied numerically. The work is based on a semi-analytical model using a Timoshenko beam theory and a full 2D finite element model. The material system analysed, is inspired by a train wagon suspension system used in a EUREKA project Sigma......!1841. For the material system, the study shows that the effect of the damping layer is strongly influenced by the presence of a stiff constraining layer, that enforces large shear strain amplitudes. The thickness of the damping rubber layer itself has only a minor influence on the overall damping....... In addition, a large influence of ill positioned cuts in the damping layer is observed....

  7. Development of APDL program for analysis of composite material multicell beams

    International Nuclear Information System (INIS)

    Tariq, M.M.; Pasha, M.; Ahmed, M.N.; Munir, A.

    2011-01-01

    Comparison of finite elements and comparison of ANSYS with MSC Patran Nastran, for analysis of composite material multicell beams, is the main idea of this paper. The Finite Element Analysis (FEA) is a valuable tool of modeling and simulation in development, processing, production and application of modern hi-tech materials and structures for reliable design. Multicell beams have important industrial applications in the automotive and aerospace sectors. ANSYS Parametric Design Language (APDL) is an important language in parametric modeling and analysis of structures with simple to complex geometry. Its major advantage is virtual prototyping which can be used to analyze and compare different materials. This work introduces core techniques required for APDL using the case study of composite multicell beams subjected to constrained torsional loading. The published results using MSC NASTRAN have been verified using ANSYS and the corresponding arising issues and notes are the focus of this research study. The details of geometry, material and boundary conditions have been explained in order to construct Finite Element (FE) model. This FE model was simulated several times in ANSYS by the authors using various options of APDL language. A step-wise flowchart was used to detect and reduce problems in iterations of analysis in APDL programming. Results of FEA largely depend on FE model and software used. These issues become prominent while trying to verify results of MSC NASTRAN with ANSYS. The author has introduced three error criteria to select an equivalent finite element of one FEA package (ANSYS) for an equivalent element of other FEA package (MSC NASTRAN). These criteria are the relative error criterion, the absolute error criterion and the combined error criterion. The results from this research provide an insight into finite elements for reliability in design of composite materials. The practical milestones for research to develop FE model and APDL programs related

  8. The modal density of composite beams incorporating the effects of shear deformation and rotary inertia

    Science.gov (United States)

    Bachoo, Richard; Bridge, Jacqueline

    2018-06-01

    Engineers and designers are often faced with the task of selecting materials that minimizes structural weight whilst meeting the required strength and stiffness. In many cases fibre reinforced composites (FRCs) are the materials of choice since they possess a combination of high strength and low density. Depending on the application, composites are frequently constructed to form long slender beam-like structures or flat thin plate-like structures. Such structures when subjected to random excitation have the potential to excite higher order vibratory modes which can contribute significantly to structure-borne sound. Statistical Energy Analysis (SEA) is a framework for modeling the high frequency vibration of structures. The modal density, which is typically defined as the number of modes per unit Hertz in a frequency band, is a fundamental parameter when applying SEA. This study derives formulas for the modal density of a fibre reinforced composite beam coupled in bending and torsion. The effects of shear deformation and rotary inertia are accounted for in the formulation. The modal density is shown to be insensitive to boundary conditions. Numerical analyses were carried out to investigate the variation of modal density with fibre orientation including and excluding the effects of shear deformation and rotary inertia. It was observed that neglecting such effects leads to underestimating the mode count in a particular frequency band. In each frequency band there exists a fibre orientation for which the modal density is minimized. This angular orientation is shown to be dependent on the shear rigidity as well as the bending, torsional and coupling rigidities. The foregoing observation becomes more pronounced with increasing frequency. The paper also addresses the modal density beyond the wave-mode transition frequency where the beam supports three propagating waves.

  9. Ionizing radiation post-curing of objects produced by stereolithography and other methods

    Science.gov (United States)

    Howell, David H.; Eberle, Claude C.; Janke, Christopher J.

    2000-01-01

    An object comprised of a curable material and formed by stereolithography or another three-dimensional prototyping method, in which the object has undergone initial curing, is subjected to post-curing by ionizing radiation, such as an electron beam having a predetermined beam output energy, which is applied in a predetermined dosage and at a predetermined dose rate. The post-cured object exhibits a property profile which is superior to that which existed prior to the ionizing radiation post-curing.

  10. Poly(methyl methacrylate) Composites with Size-selected Silver Nanoparticles Fabricated Using Cluster Beam Technique

    DEFF Research Database (Denmark)

    Muhammad, Hanif; Juluri, Raghavendra R.; Chirumamilla, Manohar

    2016-01-01

    based on cluster beam technique allowing the formation of monocrystalline size-selected silver nanoparticles with a ±5–7% precision of diameter and controllable embedment into poly (methyl methacrylate). It is shown that the soft-landed silver clusters preserve almost spherical shape with a slight...... tendency to flattening upon impact. By controlling the polymer hardness (from viscous to soft state) prior the cluster deposition and annealing conditions after the deposition the degree of immersion of the nanoparticles into polymer can be tuned, thus, making it possible to create composites with either...

  11. Innovative energy efficient low-voltage electron beam emitters

    International Nuclear Information System (INIS)

    Felis, Kenneth P.; Avnery, Tovi; Berejka, Anthony J.

    2002-01-01

    Advanced electron beams (AEB) has developed a modular, low voltage (80-125 keV), high beam current (up to 40 ma), electron emitter with typically 25 cm of beam width, that is housed in an evacuated, returnable chamber that is easy to plug in and connect. The latest in nanofabrication enables AEB to use an ultra-thin beam window. The power supply for AEB's emitter is based on solid-state electronics. This combination of features results in a remarkable electrical efficiency. AEB's electron emitter relies on a touch screen, computer control system. With 80 μm of unit density beam penetration, AEB's electron emitter has gained market acceptance in the curing of opaque, pigmented inks and coatings used on flexible substrates, metals and fiber composites and in the curing of adhesives in foil based laminates

  12. Innovative energy efficient low-voltage electron beam emitters

    Science.gov (United States)

    Felis, Kenneth P.; Avnery, Tovi; Berejka, Anthony J.

    2002-03-01

    Advanced electron beams (AEB) has developed a modular, low voltage (80-125 keV), high beam current (up to 40 ma), electron emitter with typically 25 cm of beam width, that is housed in an evacuated, returnable chamber that is easy to plug in and connect. The latest in nanofabrication enables AEB to use an ultra-thin beam window. The power supply for AEB's emitter is based on solid-state electronics. This combination of features results in a remarkable electrical efficiency. AEB's electron emitter relies on a touch screen, computer control system. With 80 μm of unit density beam penetration, AEB's electron emitter has gained market acceptance in the curing of opaque, pigmented inks and coatings used on flexible substrates, metals and fiber composites and in the curing of adhesives in foil based laminates.

  13. Influência do tipo de ponteira condutora de luz na microdureza de uma resina composta Influence of the different light-curing TIPS in the microhardness of a composite resin

    Directory of Open Access Journals (Sweden)

    Máx Dobrovolski

    2010-01-01

    Full Text Available O objetivo desta pesquisa foi avaliar a influência do tipo de ponteira condutora de luz na microdureza de uma resina composta micro-híbrida. Foram confeccionados 14 corpos de prova da resina composta Opallis (FGM com dimensões: 5 x 2 mm, divididos em dois grupos de acordo com a ponteira condutora de luz do aparelho fotoativador de lâmpada halógena Optilight Plus - GNATUS/300 mW.cm-2. GI - ponteira condutora de luz de fibra óptica; GII - ponteira condutora de luz de polímero. Após 24 horas, as medidas de microdureza foram efetuadas com um microdurômetro HMV 2000 (Shimadzu Japão. Cinco penetrações foram efetuadas em cada superfície (topo e base totalizando 10 penetrações para cada corpo de prova. A análise estatística dos resultados realizada por meio do teste de ANOVA não apresentou diferenças significativas entre os tipos de ponta condutora de luz nas superfícies avaliadas. A análise estatística demonstrou diferença significativa nos valores médios de microdureza superficial entre as superfícies de topo e de base, para ambas as ponteiras. Com base nos resultados obtidos, foi possível concluir que as ponteiras de luz não interferem na microdureza da resina composta, e que ambas apresentaram diferenças estatisticamente significativas nos valores de microdureza das superfícies topo e base.The aim of this study is to evaluate the influence of the light-curing tips on the microhardness of a micro-hybrid composite resin. Fourteen samples of Opallis (FGM composite resin with 5 x 2 mm were prepared. The specimens were divided into two groups according to the light-curing tips from a halogen light curing unit (Optilight Plus -GNATUS/300 mW.cm-2: GI - optical fiber light-curing; GII - polymer light-curing. After 24 hours, the microhardness measurements were determined using the HMV 2000 (Shimadzu Japan. Five measurements were made on each surface (top and bottom totalizing 10 indentations for each sample. Statistical analysis

  14. Do light cured ART conventional high-viscosity glass-ionomer sealants perform better than resin-composite sealants: a 4-year randomized clinical trial

    NARCIS (Netherlands)

    Zhang, W.; Chen, X.; Fan, M.W.; Mulder, J.; Huysmans, M.C.D.N.J.M.; Frencken, J.E.F.M.

    2014-01-01

    OBJECTIVE: The hypotheses tested were: the cumulative survival rates of dentin caries lesion-free pits and fissures of ART conventional high-viscosity glass-ionomer sealants with light-curing (high-intensity LED) and glass-carbomer sealants are higher than those of conventional ART sealants and

  15. Articularities of Analysis and Behaviour of Concrete Beams Reinforced with Fibrous Polymer Composite Bars

    Directory of Open Access Journals (Sweden)

    N. Ţăranu

    2006-01-01

    Full Text Available Traditional steel based reinforcement systems for concrete elements are facing with serious problems mainly caused by corrosion due to chemically aggressive environments and salts used in deicing procedures, especially in case of bridge steel reinforced concrete girders. Also in some cases special applications require structural members with magnetic transparency. An alternative to this major problem has recently become the use of fiber reinforced polymer (FPR composite bars as internal reinforcement for concrete beams. The particularities of their mechanical properties are making the design process a difficult task for engineers, numerous research centers being involved in correcting this situation. The general aspects concerning the conceiving of FR.P reinforced concrete beams are firstly analyzed, compared to those reinforced with steel bars. Some results of a Finite Element Analysis, as part of a complex program which also implies full scale testing of FRP reinforced beams subjected to bending, are given and discussed in the paper. The low elasticity modulus presented by glass fiber reinforced polymer (GFRP bars does not justify its use from structural point of view when deflection is the limiting condition but for corrosive resistance reasons and special electromagnetic properties this system can be promoted.

  16. Moment-Curvature Behaviors of Concrete Beams Singly Reinforced by Steel-FRP Composite Bars

    Directory of Open Access Journals (Sweden)

    Zeyang Sun

    2017-01-01

    Full Text Available A steel-fiber-reinforced polymer (FRP composite bar (SFCB is a kind of rebar with inner steel bar wrapped by FRP, which can achieve a better anticorrosion performance than that of ordinary steel bar. The high ultimate strength of FRP can also provide a significant increase in load bearing capacity. Based on the adequate simulation of the load-displacement behaviors of concrete beams reinforced by SFCBs, a parametric analysis of the moment-curvature behaviors of concrete beams that are singly reinforced by SFCB was conducted. The critical reinforcement ratio for differentiating the beam’s failure mode was presented, and the concept of the maximum possible peak curvature (MPPC was proposed. After the ultimate curvature reached MPPC, it decreased with an increase in the postyield stiffness ratio (rsf, and the theoretical calculation method about the curvatures before and after the MPPC was derived. The influence of the reinforcement ratio, effective depth, and FRP ultimate strain on the ultimate point was studied by the dimensionless moment and curvature. By calculating the envelope area under the moment-curvature curve, the energy ductility index can obtain a balance between the bearing capacity and the deformation ability. This paper can provide a reference for the design of concrete beams that are reinforced by SFCB or hybrid steel bar/FRP bar.

  17. Electron Beam Scanning in Industrial Applications

    Science.gov (United States)

    Jongen, Yves; Herer, Arnold

    1996-05-01

    Scanned electron beams are used within many industries for applications such as sterilization of medical disposables, crosslinking of wire and cables insulating jackets, polymerization and degradation of resins and biomaterials, modification of semiconductors, coloration of gemstones and glasses, removal of oxides from coal plant flue gasses, and the curing of advanced composites and other molded forms. X-rays generated from scanned electron beams make yet other applications, such as food irradiation, viable. Typical accelerators for these applications range in beam energy from 0.5MeV to 10 MeV, with beam powers between 5 to 500kW and scanning widths between 20 and 300 cm. Since precise control of dose delivery is required in many of these applications, the integration of beam characteristics, product conveyance, and beam scanning mechanisms must be well understood and optimized. Fundamental issues and some case examples are presented.

  18. Influence of gamma and e-beam irradiation on microhardness of recycled polyolefin-rubber composites

    International Nuclear Information System (INIS)

    Atabaev, B.G.; Gafurov, U.G.; Fainleib, A.M.; Tolstov, A.

    2006-01-01

    Full text: The dose dependencies of surface Vickers microhardness (H) for gamma and e-beam irradiated (E=5 MeV) recycled polyethylene-rubber and polypropylene-rubber composites has been investigated. The new techniques for measuring of polymer surface microhardness using decoration of indenter imprint under load lower 100g are developed. The measurements under 50g load shown the microhardness sharp decreasing for e-beam irradiation up to dose 50-150 kGy. The optimal dose D opt for improving of viscoelastic properties at minimal microhardness HV for HDPE-rubber blends-100 kGy and PP-rubber blends-75 kGy are defined. The microhardness change depend on irradiation dose can be explained by concurrence of irradiation stimulated chain cross-linking, oxidation and destruction processes. In our work samples of polyolefin powder were irradiated in air to form peroxide and hydroperoxide groups and heated to form polar groups capable of improving the compatibility with the radiation devulcanized rubber particles. The absolute value of microhardness of polyolefin-rubber composites extremely low for polyolefins and close to microhardness of high elastic rubber. The viscoelastic properties can be explained by new model of formation mixing amorphous interface between semicrystalline polyolefin and devulcanized rubber. The work was supported by EC (STCU Project U3009). (author)

  19. BOW. A computer code to predict lateral deflections of composite beams. A computer code to predict lateral deflections of composite beams

    Energy Technology Data Exchange (ETDEWEB)

    Tayal, M.

    1987-08-15

    Arrays of tubes are used in many engineered structures, such as in nuclear fuel bundles and in steam generators. The tubes can bend (bow) due to in-service temperatures and loads. Assessments of bowing of nuclear fuel elements can help demonstrate the integrity of fuel and of surrounding components, as a function of operating conditions such as channel power. The BOW code calculates the bending of composite beams such as fuel elements, due to gradients of temperature and due to hydraulic forces. The deflections and rotations are calculated in both lateral directions, for given conditions of temperatures. Wet and dry operation of the sheath can be simulated. Bow accounts for the following physical phenomena: circumferential and axial variations in the temperatures of the sheath and of the pellet; cracking of pellets; grip and slip between the pellets and the sheath; hydraulic drag; restraints from endplates, from neighbouring elements, and from the pressure-tube; gravity; concentric or eccentric welds between endcap and endplate; neutron flux gradients; and variations of material properties with temperature. The code is based on fundamental principles of mechanics. The governing equations are solved numerically using the finite element method. Several comparisons with closed-form equations show that the solutions of BOW are accurate. BOW`s predictions for initial in-reactor bow are also consistent with two post-irradiation measurements.

  20. Proton beam effects on phenolic-based composites reinforced with nanopowders

    International Nuclear Information System (INIS)

    Chhay, B.; Minamisawa, R.; Zheng, B.; Budak, S.; Ila, D.

    2007-01-01

    We have introduced various nanopowders in the precursor of glassy polymeric carbon (GPC) and studied the electrical properties as well as the chemical structure. In general the GPC ware produced at Alabama A and M University (AAMU) is used for making crucibles, heat exchangers and for prosthetic devices because of its biocompatibility and inertness. GPC ware at AAMU is synthesized from a phenolic resin solution from Georgia Pacific in a pyrolyzer system at temperatures between 100 deg, C and 2800 deg, C. The heat treatment includes several stages: gelling, curing, postcuring, precarbonization and carbonization. The fabrication of GPC is complicated because of the high production rate of gaseous products in critical temperature ranges where out-diffusion is relatively slow. Special care should be taken in temperature programming to avoid kilning faults and misshapen or porous GPC end results [H. Maleki, L.R. Holland, G.M. Jenkins, et al., Carbon 35 (1997) 227]. In this work we have introduced 1 wt% of SiC, carbon nanotubes (CNT) and Al 2 O 3 to the precursor, pyrolyzed composites to 1000 deg, C and studied the effect of 1 MeV and 3 MeV proton bombardment on the final products

  1. Effect of Light Curing Unit Characteristics on Light Intensity Output ...

    African Journals Online (AJOL)

    Background: Modern dental composite restorations are wholly dependent on the use of Visible Light Curing devices. The characteristics of these devices may influence the quality of composite resin restorations. Objective: To determine the characteristics of light curing units (LCUs) in dental clinics in Nairobi and their effect ...

  2. Comparison of composite rotor blade models: A coupled-beam analysis and an MSC/NASTRAN finite-element model

    Science.gov (United States)

    Hodges, Robert V.; Nixon, Mark W.; Rehfield, Lawrence W.

    1987-01-01

    A methodology was developed for the structural analysis of composite rotor blades. This coupled-beam analysis is relatively simple to use compared with alternative analysis techniques. The beam analysis was developed for thin-wall single-cell rotor structures and includes the effects of elastic coupling. This paper demonstrates the effectiveness of the new composite-beam analysis method through comparison of its results with those of an established baseline analysis technique. The baseline analysis is an MSC/NASTRAN finite-element model built up from anisotropic shell elements. Deformations are compared for three linear static load cases of centrifugal force at design rotor speed, applied torque, and lift for an ideal rotor in hover. A D-spar designed to twist under axial loading is the subject of the analysis. Results indicate the coupled-beam analysis is well within engineering accuracy.

  3. Polyurethane acrylate networks including cellulose nanocrystals: a comparison between UV and EB- curing

    International Nuclear Information System (INIS)

    Furtak-Wrona, K.; Kozik-Ostrówka, P.; Jadwiszczak, K.; Maigret, J.E.; Aguié-Béghin, V.; Coqueret, X.

    2018-01-01

    A water-based polyurethane (PUR) acrylate water emulsion was selected as a radiation curable matrix for preparing nanocomposites including cellulose nanocrystals (CNC) prepared by controlled hydrolysis of Ramie fibers. Cross-linking polymerization of samples prepared in the form of films or of 1 mm-thick bars was either initiated by exposure to the 395 nm light of a high intensity LED lamp or by treatment with low energy electron beam (EB). The conversion level of acrylate functions in samples submitted to increasing radiation doses was monitored by Fourier Transform Infrared Spectroscopy (FTIR). Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) were used to characterize changes in the glass transition temperature of the PUR-CNC nanocomposites as a function of acrylate conversion and of CNC content. Micromechanical testing indicates the positive effect of 1 wt% CNC on Young's modulus and on the tensile strength at break (σ) of cured nanocomposites. The presence of CNC in the PUR acrylate matrix was shown to double the σ value of the nanocomposite cured to an acrylate conversion level of 85% by treatment with a 25 kGy dose under EB, whereas no increase of σ was observed in UV-cured samples exhibiting the same acrylate conversion level. The occurrence of grafting reactions inducing covalent linkages between the polysaccharide nanofiller and the PUR acrylate matrix during the EB treatment is advanced as an explanation to account for the improvement observed in samples cured under ionizing radiation. - Highlights: • Nanocomposites were prepared from o/w PUR acrylate emulsion and CNC suspension. • Nanocomposite and reference materials were cured to the same conversion by UV or EB. • Introducing 1 wt% CNC in EB-cured composites doubles the tensile strength. • UV-cured nanocomposites did not show significant improvement in tensile strength.

  4. Evaluation of parameters associated with UV/EB cured clearcoats degradation used in outdoor environment

    International Nuclear Information System (INIS)

    Ruiz, Carmen Silvia Bentivoglio

    2003-01-01

    The materials curable by ultraviolet (UV) or electron beam (EB) radiation such as inks, adhesives and coatings are reactive compounds made up of resin, monomer, photoinitiator and additives which undergo polymerization and crosslinking under irradiation producing thermoset products. This technology has been used in a great variety of industrial applications, replacing the conventional curing process in the development of new products. One of the challenging applications has been to design weatherable radiation cured coating which maintain their desirable physical properties and aesthetic appearance. This research reports information about the behavior of four UV and EB curable clear coatings -with or without light stabilizer additives- under accelerated weathering. Thermogravimetry, differential scanning calorimetry, differential photo calorimetry, infrared and ultraviolet spectroscopy and tensile properties were used to evaluate these formulations. Clear coating 50 mum thick films were cured with UV and EB radiation at different doses. The UV curing process was carried out at room temperature using an UV tunnel, with a medium pressure mercury lamp and a transport belt with variable speed. The ultraviolet radiation doses were in the range of 50 to 1500 mJ cm -2 . The EB curing process was performed under N 2 atmosphere, with doses in the range from 1,6 to 300 kGy using the IPEN-CNEN/SP Dynamitron electron beam accelerator with energy of 1.5 MeV. The cure degree was determined by means of the residual reaction heat of the under cured samples obtained from photo-DSC or DSC measurements. The accelerated aging tests were carried out using a Weather-Ometer chamber with exposition times in the range of 100 to 3000 hours. The experimental data obtained from the photo-aged samples were evaluated and correlated to the formulation composition, type of radiation - UV or EB, radiation dose and residence time in the aging chamber. The results have shown that the EB cured films

  5. Study on the Unsteady Creep of Composite Beams with an Irregular Laminar Fibrous Structure Made from Nonlinear Hereditary Materials

    Science.gov (United States)

    Yankovskii, A. P.

    2017-09-01

    The creep of homogenous and hybrid composite beams of an irregular laminar fibrous structure is investigated. The beams consist of thin walls and flanges (load-carrying layers). The walls may be reinforced longitudinally or crosswise in the plane, and the load-carrying layers are reinforced in the longitudinal direction. The mechanical behavior of phase materials is described by the Rabotnov nonlinear hereditary theory of creep taking into account their possible different resistance to tension and compression. On the basis of hypotheses of the Timoshenko theory, with using the method of time steps, a problem is formulated for the inelastic bending deformation of such beams with account of the weakened resistance of their walls to the transverse shear. It is shown that, at discrete instants of time, the mechanical behavior of such structures can formally be described by the governing relations for composite beams made of nonlinear elastic anisotropic materials with a known initial stress state. The method of successive iterations, similar to the method of variable parameters of elasticity, is used to linearize the boundary-value problem at each instant of time. The bending deformation is investigated for homogeneous and reinforced cantilever and simply supported beams in creep under the action of a uniformly distributed transverse load. The cross sections of the beams considered are I-shaped. It is found that the use of the classical theory for such beams leads to the prediction of indefensibly underestimated flexibility, especially in long-term loading. It is shown that, in beams with reinforced load-carrying layers, the creep mainly develops due to the shear strains of walls. It is found that, in short- and long-term loadings of composite beams, the reinforcement structures rational by the criterion of minimum flexibility are different.

  6. A finite element modeling of a multifunctional hybrid composite beam with viscoelastic materials

    Science.gov (United States)

    Wang, Ya; Inman, Daniel J.

    2013-04-01

    The multifunctional hybrid composite structure studied here consists of a ceramic outer layer capable of withstanding high temperatures, a functionally graded ceramic layer combining shape memory alloy (SMA) properties of NiTi together with Ti2AlC (called Graded Ceramic/Metal Composite, or GCMeC), and a high temperature sensor patch, followed by a polymer matrix composite laced with vascular cooling channels all held together with various epoxies. Due to the recoverable nature of SMA and adhesive properties of Ti2AlC, the damping behavior of the GCMeC is largely viscoelastic. This paper presents a finite element formulation for this multifunctional hybrid structure with embedded viscoelastic material. In order to implement the viscoelastic model into the finite element formulation, a second order three parameter Golla-Hughes-McTavish (GHM) method is used to describe the viscoelastic behavior. Considering the parameter identification, a strategy to estimate the fractional order of the time derivative and the relaxation time is outlined. The curve-fitting aspects of both GHM and ADF show good agreement with experimental data obtained from dynamic mechanics analysis. The performance of the finite element of the layered multifunctional beam is verified through experimental model analysis.

  7. Modification of composite por -Si/SnOx power ion beam of nanosecond duration

    International Nuclear Information System (INIS)

    Korusenko, P.M.; Bolotov, V.V.; Knyazev, E.V.; Kovivchak, V.S.; Korepanov, A.A.; Nesov, S.N.; Povoroznyuk, S.N.

    2011-01-01

    The results of XPS (X-ray photoelectron spectroscopy), AES (Auger electron spectroscopy) and SEM (Scanning electron microscopy) investigation of tin oxide nanolayers on the samples of the composite por-Si/SnO x with different porosity of the matrix, formed under the influence of a powerful ion beam of nanosecond duration was presented. It is shown that fast melting and crystallization of the surface leads to the formation of globular structures with a typical size of 200 nm. Established that the tin is included in structure of the nanocomposite in the oxidized state with little inclusion of metallic β-tin. With increasing porosity, phase composition of nanolayers of tin is close to the state corresponding to the higher tin oxide SnO 2 . Also shows that with increasing porosity, the intensity of subvalent 4d lines of tin, which is apparently associated with an increased degree of hybridization of the tin atoms and oxygen atoms. According to the results stratified etching was to evaluate the changes of the elemental structure of the composite and the depth of penetration of tin. (authors)

  8. Grafting and curing

    International Nuclear Information System (INIS)

    Garnett, J.L.; Loo-Teck Ng; Visay Viengkhou

    1998-01-01

    Progress in radiation grafting and curing is briefly reviewed. The two processes are shown to be mechanistically related. The parameters influencing yields are examined particularly for grafting. For ionising radiation grafting systems (EB and gamma ray) these include solvents, substrate and monomer structure, dose and dose-rate, temperature and more recently role of additives. In addition, for UV grafting, the significance of photoinitiators is discussed. Current applications of radiation grafting and curing are outlined. The recent development of photoinitiator free grafting and curing is examined as well as the potential for the new excimer laser sources. The future application of both grafting and curing is considered, especially the significance of the occurrence of concurrent grafting during cure and its relevance in environmental considerations

  9. Behavior of thin-walled beams made of advanced composite materials and incorporating non-classical effects

    Science.gov (United States)

    Librescu, Liviu; Song, Ohseop

    1991-11-01

    Several results concerning the refined theory of thin-walled beams of arbitrary closed cross-section incorporating nonclassical effects are presented. These effects are related both with the exotic properties characterizing the advanced composite material structures and the nonuniform torsional model. A special case of the general equations is used to study several problems of cantilevered thin-walled beams and to assess the influence of the incorporated effects. The results presented in this paper could be useful toward a more rational design of aeronautical or aerospace constructions, as well as of helicopter or tilt rotor blades constructed of advanced composite materials.

  10. Optical properties of YbF3-CaF2 composite thin films deposited by electron-beam evaporation

    Science.gov (United States)

    Wang, Songlin; Mi, Gaoyuan; Zhang, Jianfu; Yang, Chongmin

    2018-03-01

    We studied electron-beam evaporated YbF3-CaF2 composite films on ZnS substrate at different deposition parameters. The optical properties of films have been fitted, the surface roughness have been measured by AFM. The results of experiments indicated that increased the refractive indices, extinction coefficients, and surface roughness at higher deposition rate. The refractive index of composite film deposited by electron-beam evaporation with assisted-ion source was obviously higher than it without assisted-ion source.

  11. Erosion resistance of composite materials on titanium, zirconium and aluminium nitride base under the electron beam effect

    International Nuclear Information System (INIS)

    Verkhoturov, A.D.; Kuzenkova, M.A.; Slutskin, M.G.; Kravchuk, L.A.

    1977-01-01

    Erosion resistance of composites based on nitrides of titanium, zirconium and aluminium to spark and electron beam processing has been studied. The erosion resistance in spark processing is shown to depend on specific electric resistance of the alloys. TiN-AlN and ZrN-AlN alloys containing more than 70% AlN (with specific electric resistance more than 10 6 -10 7 ohm/cm) caot be processed by spark method. It is shown that erosion of the composites by an electron beam depends primarily on the rate of evaporation of the components

  12. Application of a silver–olefin coordination polymer as a catalytic curing agent for self-healing epoxy polymers

    International Nuclear Information System (INIS)

    Everitt, D T; Coope, T S; Trask, R S; Bond, I P; Wass, D F

    2015-01-01

    A silver–olefin based coordination polymer was prepared in a simple, one step process to act as an initiator to facilitate the ring-opening polymerization of epoxides. Thermal analysis found the complex to be capable of curing a range of commercially available epoxy resins used in the manufacture of conventional composite materials. Curing of the oligomeric diglycidyl ether bisphenol A resin, Epon 828, in combination with a non-toxic solvent, ethyl phenylacetate, was studied by differential scanning calorimetry. The mechanical characterization of the resultant cured polymers was conducted by single lap shear tests. Tapered double cantilever beam (TDCB) test specimens containing 2.5 pph of silver–olefin initiator, both with and without embedded microcapsules, were analyzed for their healing performance. Healing efficiency values were found to be strongly dependent on the applied healing temperature. A mean recovery of 74% fracture load was found in TDCB samples after being healed at 70 °C for 48 h. (paper)

  13. Study of a hybrid solar-electric oven to the curing composite materials used in aeronautics; Estudio de un horno hibrido solar-electrico para el curado de materiales compuestos utilizados en aeronautica

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Roman, M. A.; Pineda Pinon, J.; Sanchez Sanchez, A. [CICATA - Unidad Queretaro, Santiago de Queretaro, Queretaro (Mexico)]. E-mail: mhernandezr0900@ipn.mx

    2010-11-15

    The study covers the curing of advanced composites in a hybrid solar electric oven. The furnace uses electricity from the grid power and solar energy provided by the heliostat concentrator system. The materials used in the experiments will be composite materials such as prepreg. The prepreg are fiberglass and carbon fiber. The resin used in the pre-impregnate will be epoxy resin. The work temperatures inside the furnace will be maximum 300 degrees Celsius. The obtained results will be useful to characterize the use of the solar energy and the characterize of the curing chamber. [Spanish] Se presenta el alcance para el estudio, el cual abarca el curado de materiales compuestos avanzados dentro de un horno hibrido solar electrico. El horno utilizara energia electrica suministrada por la red y energia solar suministrada por el sistema heliostato concentrador. Los materiales utilizados en los experimentos seran materiales compuestos tipo prepreg. Los prepreg seran de fibra de vidrio y de fibra de carbono. La resina utilizada en el preimpregando sera resina epoxica. Las temperaturas de trabajo dentro del horno seran como maximo de 300 grados centigrados. Los resultados obtenidos serviran para caracterizar el uso y aprovechamiento de la energia solar y la caracterizacion de la camara de curado.

  14. Electron beam curable polymer thick film

    International Nuclear Information System (INIS)

    Nagata, Hidetoshi; Kobayashi, Takashi

    1988-01-01

    Currently, most printed circuit boards are produced by the selective etching of copper clads laminated on dielectric substrates such as paper/phenolic resion or nonwoven glass/epoxy resin composites. After the etchig, various components such as transistors and capacitors are mounted on the boards by soldering. But these are troublesome works, therefore, as an alternative, printing method has been investigated recently. In the printing method, conductor circuits and resistors can be made by printing and curing of the specially prepared paste on dielectric substrates. In the near future, also capacitors are made by same method. Usually, conductor paste, resistor paste and dielectric paste are employed, and in this case, the printing is screen printing, and the curing is done thermally. In order to avoid heating and the deterioration of substrates, attention was paid to electron beam curing, and electron beam curable polymer thick film system was developed. The electron beam curable paste is the milled mixture of a filler and an electron beam curable binder of oligomer/monomer. The major advantage of electron beam curable polymer thick film, the typical data of a printed resistor of this type and its trial are reported. (K.I.)

  15. Quantitative SIMS analysis of SiGe composition with low energy O2+ beams

    International Nuclear Information System (INIS)

    Jiang, Z.X.; Kim, K.; Lerma, J.; Corbett, A.; Sieloff, D.; Kottke, M.; Gregory, R.; Schauer, S.

    2006-01-01

    This work explored quantitative analyses of SiGe films on either Si bulk or SOI wafers with low energy SIMS by assuming a constant ratio between the secondary ion yields of Si + and Ge + inside SiGe films. SiGe samples with Ge contents ranging from 15 to 65% have been analyzed with a 1 keV O 2 + beam at normal incidence. For comparison, the samples were also analyzed with RBS and/or AES. The Ge content as measured with SIMS, based on a single SiGe/Si or SiGe/SOI standard, exhibited good agreement with the corresponding RBS and AES data. It was concluded that SIMS was capable of providing accurate characterization of the SiGe composition with the Ge content up to 65%

  16. Nuclear micro-beam analysis of deuterium distribution in carbon fibre composites for controlled fusion devices

    International Nuclear Information System (INIS)

    Petersson, P.; Kreter, A.; Possnert, G.; Rubel, M.

    2010-01-01

    Probes made of carbon fibre composite NB41 were exposed to deuterium plasmas in the TEXTOR tokamak and in a simulator of plasma-wall interactions, PISCES. The aim was to assess the deuterium retention and its lateral and depth distribution. The analysis was performed by means of D( 3 He, p) 4 He and 12 C( 3 He, p) 14 N nuclear reactions analysis using a standard (1 mm spot) and micro-beam (20 μm resolution). The measurements have revealed non uniform distribution of deuterium atoms in micro-regions: differences by a factor of 3 between the maximum and minimum deuterium concentrations. The differences were associated with the orientation and type of fibres for samples exposed in PICSES. For surface structure in the erosion zone of samples exposed to a tokamak plasma the micro-regions were more complex. Depth profiling has indicated migration of fuel into the bulk of materials.

  17. Physical properties of wood-polymer composites prepared by an electron beam accelerator

    International Nuclear Information System (INIS)

    Yoshizawa, S.; Handa, T.; Fukuoka, M.; Hashizume, Y.; Nakamura, T.

    1981-01-01

    The dual characteristics in the performance of polymers in wood-polymer composites systems have been pursued with regard to the resolution of mechanical anisotropy of wood and the improvement in dimensional stability. The objective of the present study is to pursue the polymerization mechanism in wood under electron beam irradiation and the temperature dependence of polymer-wood interactions induced at various levels of higher order structure of wood in order to understand the polymer performance. Veneers used in the study were of rotary-cut beech (Fagus crenata Blume) 0.65 mm thick. All samples were oven-dried in vacuo at 80 0 C for 30 hr. The monomers used in the study were methyl methacrylate, styrene, acrylic acid, acrylonitrile, and unsaturated polyester. Experimental details are given. Results are given and discussed. (U.K.)

  18. A curved beam test specimen for determining the interlaminar tensile strength of a laminated composite

    Science.gov (United States)

    Hiel, Clement C.; Sumich, Mark; Chappell, David P.

    1991-01-01

    A curved beam type of test specimen is evaluated for use in determining the through-the-thickness strength of laminated composites. Two variations of a curved beam specimen configuration (semicircular and elliptical) were tested to failure using static and fatigue loads. The static failure load for the semicircular specimens was found to be highly sensitive to flaw content, with the specimens falling into two distinct groups. This result supports the use of proof testing for structural validation. Static design allowables are derived based on the Weibull distribution. Fatigue data indicates no measured increase in specimen compliance prior to final fracture. All static and fatigue failures at room temperature dry conditions occurred catastrophically. The elliptical specimens demonstrated unusually high failure strengths indicating the presence of phenomena requiring further study. Results are also included for specimens exposed to a wet environment showing a matrix strength degradation due to moisture content. Further testing is underway to evaluate a fatigue methodology for matrix dominated failures based on residual static strength (wearout).

  19. RC beams shear-strengthened with fabric-reinforced-cementitious-matrix (FRCM) composite

    Science.gov (United States)

    Loreto, Giovanni; Babaeidarabad, Saman; Leardini, Lorenzo; Nanni, Antonio

    2015-12-01

    The interest in retrofit/rehabilitation of existing concrete structures has increased due to degradation and/or introduction of more stringent design requirements. Among the externally-bonded strengthening systems fiber-reinforced polymers is the most widely known technology. Despite its effectiveness as a material system, the presence of an organic binder has some drawbacks that could be addressed by using in its place a cementitious binder as in fabric-reinforced cementitious matrix (FRCM) systems. The purpose of this paper is to evaluate the behavior of reinforced concrete (RC) beams strengthened in shear with U-wraps made of FRCM. An extensive experimental program was undertaken in order to understand and characterize this composite when used as a strengthening system. The laboratory results demonstrate the technical viability of FRCM for shear strengthening of RC beams. Based on the experimental and analytical results, FRCM increases shear strength but not proportionally to the number of fabric plies installed. On the other hand, FRCM failure modes are related with a high consistency to the amount of external reinforcement applied. Design considerations based on the algorithms proposed by ACI guidelines are also provided.

  20. Anchorage strength models for end-debonding predictions in RC beams strengthened with FRP composites

    Science.gov (United States)

    Nardini, V.; Guadagnini, M.; Valluzzi, M. R.

    2008-05-01

    The increase in the flexural capacity of RC beams obtained by externally bonding FRP composites to their tension side is often limited by the premature and brittle debonding of the external reinforcement. An in-depth understanding of this complex failure mechanism, however, has not yet been achieved. With specific regard to end-debonding failure modes, extensive experimental observations reported in the literature highlight the important distinction, often neglected in strength models proposed by researchers, between the peel-off and rip-off end-debonding types of failure. The peel-off failure is generally characterized by a failure plane located within the first few millimetres of the concrete cover, whilst the rip-off failure penetrates deeper into the concrete cover and propagates along the tensile steel reinforcement. A new rip-off strength model is described in this paper. The model proposed is based on the Chen and Teng peel-off model and relies upon additional theoretical considerations. The influence of the amount of the internal tensile steel reinforcement and the effective anchorage length of FRP are considered and discussed. The validity of the new model is analyzed further through comparisons with test results, findings of a numerical investigation, and a parametric study. The new rip-off strength model is assessed against a database comprising results from 62 beams tested by various researchers and is shown to yield less conservative results.

  1. Comparação da influência entre tempos de polimerização em resinas compostas polimerizadas com LED e Luz Incandescente Comparison of the influence of curing times applied to composite resins cured with LED and Incandescent Light

    Directory of Open Access Journals (Sweden)

    Michele P. M. Ulhoa

    2007-09-01

    method, the resin with highest wear was the Tetric Ceram, cured with LED device for 10 s (aggressiveness average 0.170 mm³/N.m . The composite resin with least wear was Charisma, cured with halogen lamp device for 20 s (aggressiveness average 0.057 mm³/N.m .

  2. Process for hardening an alkyd resin composition using ionizing radiation. [electron beams, gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, T; Murata, K; Maruyama, T

    1969-11-27

    In an alkyd resin composition having free hydroxide radicals and containing a conjugated unsaturated fatty acid and/or oil as a component thereof, a process for hardening an alkyd resin composition comprises the steps of dissolving into a vinyl monomer, the product obtained by the semi-esterification reaction of said hydroxide radicals with acid anhydrides having polymerizable radicals and hardening by ionizing radiation to provide a coating with a high degree of cross-linking, with favorable properties such as toughness, hardness, chemical resistance and resistance to weather and with the feasibility of being applied as the ground and finish coat on metals, wood, paper, outdoor construction or the like. Any kind of ionization radiation, particularly accelerated electron beams, ..gamma.. radiation can be used at 50/sup 0/C to -5/sup 0/C for a few seconds or minutes, permitting continuous operation. In one example, 384 parts of phthalic anhydride, 115 parts of pentaerythritol, 233 parts of trimethylol ethane, 288 parts of tung fatty acid and 49 parts of para-tertiary-butyl benzoic acid are mixed and heated with 60 parts of xylene to an acid value of 12. In addition, 271 parts of maleic anhydride and 0.6 parts of hydroquinone are admixed with the content and heated to terminate the reaction. 100 parts of a 50% stylene solution of this alkyd resin are mixed with 1 part of a 60% toluene solution of cobalt naphthenate, and then coated on a glass plate and irradiated with high energy electron beams of 300 kV with a dose of 5 Mrad for 1 sec.

  3. Effect of sterilization dose on electron beam irradiated biodegradable polymers and coconut fiber based composites

    Energy Technology Data Exchange (ETDEWEB)

    Kodama, Yasko; Machado, Luci D.B., E-mail: ykodama@ipen.b, E-mail: lmachado@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Oishi, Akihiro; Nakayama, Kazuo, E-mail: a.oishi@aist.go.j, E-mail: kazuo-nakayama@jcom.home.ne.j [National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki-ken (Japan). Research Institute for Sustainable Chemical Innovation; Nagasawa, Naotsugu; Tamada, Masao, E-mail: nagasawa.naotsugu@jaea.go.j [Japan Atomic Energy Agency (JAEA), Gunma-ken (Japan). Quantum Beam Science Directorate

    2009-07-01

    In Brazil, annual production of coconut fruit is 1.5 billion in a cultivated area of 2.7 million ha. Coconut fiber applications as reinforcement for polymer composites, besides reducing the coconut waste, would reduce cost of the composite. On the other hand, biodegradable polymers have been receiving much attention due to the plastic waste problem. Poly(e-caprolactone), PCL, and poly(lactic acid), PLA, besides being biodegradable aliphatic polyesters, are biocompatible polymers. Considering the biomedical application of PLA and PCL, their products must be sterilized for use, and ionizing radiation has been widely used for medical devices sterilization. It is important to study the effect of ionizing radiation on the blends and composites due to the fact that they are based on biocompatible polymers. Is this research, hot pressed samples based on PLA:PCL (80:20, ratio of weight:weight) blend and the composites containing chemically treated or untreated coconut fiber (5, 10%) were irradiated by electron beams and gamma radiation from Co-60 source at doses in the range up to 200 kGy. Thermal mechanical analysis (TMA) and gel fraction measurements were performed in irradiated samples. From TMA curves it can be observed that thermal stability of samples with untreated coconut fiber slightly decreased with increasing fiber content. On the other hand, deformation increased with increasing fiber content. Acetylated coconut fibers slightly decreased thermal stability of samples. It seems that no interaction occurs between the natural fibers and the polymeric matrix due to irradiation. PLLA undergoes to main chain scission under ionizing irradiation according to thermal stability results and also because no gel fraction was observed. In contrast, PCL cross-linking is induced by ionizing radiation that increases thermal stability and decreases deformation. (author)

  4. Effect of sterilization dose on electron beam irradiated biodegradable polymers and coconut fiber based composites

    International Nuclear Information System (INIS)

    Kodama, Yasko; Machado, Luci D.B.; Oishi, Akihiro; Nakayama, Kazuo; Nagasawa, Naotsugu; Tamada, Masao

    2009-01-01

    In Brazil, annual production of coconut fruit is 1.5 billion in a cultivated area of 2.7 million ha. Coconut fiber applications as reinforcement for polymer composites, besides reducing the coconut waste, would reduce cost of the composite. On the other hand, biodegradable polymers have been receiving much attention due to the plastic waste problem. Poly(e-caprolactone), PCL, and poly(lactic acid), PLA, besides being biodegradable aliphatic polyesters, are biocompatible polymers. Considering the biomedical application of PLA and PCL, their products must be sterilized for use, and ionizing radiation has been widely used for medical devices sterilization. It is important to study the effect of ionizing radiation on the blends and composites due to the fact that they are based on biocompatible polymers. Is this research, hot pressed samples based on PLA:PCL (80:20, ratio of weight:weight) blend and the composites containing chemically treated or untreated coconut fiber (5, 10%) were irradiated by electron beams and gamma radiation from Co-60 source at doses in the range up to 200 kGy. Thermal mechanical analysis (TMA) and gel fraction measurements were performed in irradiated samples. From TMA curves it can be observed that thermal stability of samples with untreated coconut fiber slightly decreased with increasing fiber content. On the other hand, deformation increased with increasing fiber content. Acetylated coconut fibers slightly decreased thermal stability of samples. It seems that no interaction occurs between the natural fibers and the polymeric matrix due to irradiation. PLLA undergoes to main chain scission under ionizing irradiation according to thermal stability results and also because no gel fraction was observed. In contrast, PCL cross-linking is induced by ionizing radiation that increases thermal stability and decreases deformation. (author)

  5. Development of improved asbestos reinforced phenolic insulating composites (optimization of physical properties as a function of molding technique and post cure conditions)

    Science.gov (United States)

    Hedges, L. M. (Editor)

    1973-01-01

    Detailed data are presented on phenolic-glass and phenolic-asbestos compounds which compare the effect of compression molding without degas to the effects of four variations of compression molding. These variations were designed to improve elimination of entrapped volatiles and the volatile products of the condensate reaction associated with the cure of phenolic resins. The utilization of conventional methods of degas plus degas by vacuum and directional heat flow methods are involved. Detailed data are also presented on these same compounds, comparing the effect of changes in post-bake time, and post-bake temperature for the five molding techniques.

  6. Radiation curing: Science and technology

    International Nuclear Information System (INIS)

    Pappas, S.P.

    1992-01-01

    The science and technology of radiation curing have progressed substantially within the last 20 years. Nevertheless, radiation-curable compositions typically command relatively small shares in many of their competitive markets. This situation signifies that potential advantages of radiation curing are not generally perceived to overcome their limitations. An important objective of this book is to address this issue, within the scope of the subjects offered, by providing the present state of knowledge and by identifying the directions and challenges for future studies. The first chapter introduces radiation curing. Chapter 2 offers the first systematic presentation of inorganic and organometallic photoinitiators. Chapters 3 and 4 present the analytical techniques of photocalorimetry and real-time infrared spectroscopy, respectively. Recent advances in resin technology are offered in Chapters 5 and 6, which constitute the first comprehensive accounts of (meth)acrylated silicones and vinyl ethers, respectively. Radiation-curable coatings, printing inks, and adhesives are discussed in Chapters 7-9, respectively. Chapter 10 offers a discussion on photopolymer imaging systems

  7. A comparative study for different shielding material composition and beam geometry applied to PET facilities: simulated transmission curves

    OpenAIRE

    Hoff, Gabriela; Costa, Paulo Roberto

    2013-01-01

    The aim of this work is to simulate transmission data for different beam geometry and material composition in order to evaluate the effect of these parameters on transmission curves. The simulations are focused on outgoing spectra for shielding barriers used in PET facilities. The behavior of the transmission was evaluated as a function of the shielding material composition and thickness using Geant4 Monte Carlo code, version 9.2 p 03.The application was benchmarked for barited mortar and com...

  8. Accuracy of near infrared spectroscopy for prediction of chemical composition, salt content and free amino acids in dry-cured ham.

    Science.gov (United States)

    Prevolnik, Maja; Škrlep, Martin; Janeš, Lucija; Velikonja-Bolta, Spela; Škorjanc, Dejan; Čandek-Potokar, Marjeta

    2011-06-01

    The capability of near infrared (NIR) spectroscopy was examined for the purposes of quality control of the traditional Slovenian dry-cured ham "Kraški pršut." Predictive models were developed for moisture, salt, protein, non-protein nitrogen, intramuscular fat and free amino acids in biceps femoris muscle (n = 135). The models' quality was assessed using statistical parameters: coefficient of determination (R(2)) and standard error (se) of cross-validation (CV) and external validation (EV). Residual predictive deviation (RPD) was also assessed. Best results were obtained for salt content and salt percentage in moisture/dry matter (R(CV)(2)>0.90, RPD>3.0), it was satisfactory for moisture, non-protein nitrogen, intramuscular fat and total free amino acids (R(CV)(2) = 0.75-0.90, RPD = 2.0-3.0), while not so for protein content and proteolysis index (R(CV)(2) = 0.65-0.75, RPD<2.0). Calibrations for individual free amino acids yielded R(CV)(2) from 0.40 to 0.90 and RPD from 1.3 to 2.9. Additional external validation of models on independent samples yielded comparable results. Based on the results, NIR spectroscopy can replace chemical methods in quality control of dry-cured ham. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Thermogravimetric Characterization of the Microstructui Composition of Polyamide Injection Molded Denture Base Material vs Conventional Compression Molded Heat-cured Denture Base Material.

    Science.gov (United States)

    Al-Dharrab, Ayman; Shinawi, Lana

    2016-02-01

    Thermoplastic resin polymers are widely used in medicine due to their biostability and hypoallergenic properties, making them a possible alternative to poly-methylmethacrylate (PMMA). The current research examined the microstructure of a rapid injection molding system thermoplastic resin for construction of flexible denture compared with that of heat-cured PMMA. A total of 40 disk-shaped specimens (25 mm in diameter and 3 mm in thickness) were prepared and divided into two groups of 20 disks each (group I samples were of thermoplastic acrylic resin while group II was heat-cured PMMA resin). In group I, thermogravimetric analyzer showed that increasing the temperature up to 169°C resulted in about 1.3% of the material loss, and after that the material remains thermally stable up to 200°C. Group 11 showed 2.24% weight loss at 171°C, and further weight loss (12.025%) was observed on heating to 230°C. Fourier transform infrared (FTIR) spectrophotometer analysis in the range of 400-4000 cm(-1) detected the presence of an amine group (N-H) in group I samples and the presence of methylene group attached to inorganic Si as reinforcement filler (Si-CH3). Thermoplastic resin displayed excellent thermal stability and the absence of residual monomer within the polymerized material, suggesting its suitability for the fabrication dentures.

  10. Electron-beam irradiation effects on mechanical properties of PEEK/CF composite

    International Nuclear Information System (INIS)

    Sasuga, Tsuneo; Seguchi, Tadao

    1989-01-01

    Carbon fibre-reinforced composite (PEEK/CF) using polyarylether-ether-ketone (PEEK) as a matrix material was prepared and electron-beam irradiation effects on the mechanical properties at low and high temperatures were studied. The flexural strength and modulus of the unirradiated PEEK/CF were almost the same as those of carbon fibre-reinforced composites with epoxide resin. The mechanical properties at room temperature were little affected by irradiation up to 180 MGy, but in the test at 77K the strength of the specimens irradiated over 100 MGy was slightly decreased. The mechanical properties of the unirradiated specimen decreased with increasing testing temperature, but the high-temperature properties were improved by irradiation, i.e. the strength measured at 413K for the specimen irradiated with 120 MGy almost reached the value for the unirradiated specimen measured at room temperature. It was apparent from the viscoelastic measurement that the improvement of mechanical properties at high temperature resulted from the high-temperature shift of the glass transition of the matrix PEEK caused by radiation-induced cross-linking. (author)

  11. Analysis of a hybrid balanced laminate as a structural material for thick composite beams with axial stiffeners

    Energy Technology Data Exchange (ETDEWEB)

    Modak, Partha; Hossain, M. Jamil, E-mail: jamil917@gmail.com; Ahmed, S. Reaz [Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh)

    2016-07-12

    An accurate stress analysis has been carried out to investigate the suitability of a hybrid balanced laminate as a structural material for thick composite beams with axial stiffeners. Three different balanced laminates composed of dissimilar ply material as well as fiber orientations are considered for a thick beam on simple supports with stiffened lateral ends. A displacement potential based elasticity approach is used to obtain the numerical solution of the corresponding elastic fields. The overall laminate stresses as well as individual ply stresses are analysed mainly in the perspective of laminate hybridization. Both the fiber material and ply angle of individual laminas are found to play dominant roles in defining the design stresses of the present composite beam.

  12. C-CURE

    Data.gov (United States)

    US Agency for International Development — C-CURE system manages certain aspects of the access control system, including collecting employee and contractor names and photographs. The Office of Security uses...

  13. Radiation curing of mixture of diallylphthalate prepolymer and vinyl monomer, 11

    International Nuclear Information System (INIS)

    Gotoda, Masao; Yagi, Toshiaki; Yoshizawa, Iwao; Okugawa, Hideo.

    1975-01-01

    Preparation of Wood-Polymer Composite (WPC) piled plywood for flooring, was attempted by electron beam irradiation of American Hemlock veneer, impregnated with low molecular weight diallylphthalate prepolymer (DAPsub(p).L)/vinyl monomer mixtures, in comparison with that by thermal curing reported previously. For the improvement of the mechanical properties of WPC piled plywood, 5-15 parts of low molecular weight polyvinylacetate (PVAc) was added to DAPsub(p).L/methyl acrylate/hydroxyethyl acrylate/benzoyl peroxide (50/40/10/2) mixture. The addition of PVAc did not give much influence to the degree of impregnation in the veneer and to the curability by electron beam irradiation. As to the resistance to hot and cold cycle test, WPC piled plywood, prepared by the resin containing 5 parts of PVAc gave the best results. As a general conclusion, due to the superior mechanical properties, the WPC piled plywood processed by electron beam irradiation is suitable for flooring use. (author)

  14. Sugarcane bagasse ash reinforced HDPE composites: effects of electron-beam radiation crosslinking on tensile and morphological properties

    International Nuclear Information System (INIS)

    Teixeira, Jaciele G.; Gomes, Michelle G.; Oliveira, Rene R.; Silva, Valquiria A.; Sartori, Mariana M.; Ortiz, Angel V.; Moura, Esperidiana A.B.

    2013-01-01

    Environmental issues have led to the development of polymeric materials reinforced with fibers originated from renewable agricultural sources such as pineapple leaf, sisal, jute, piassava, coir, and sugarcane bagasse. Although sugarcane bagasse fiber residues has been extensively studied and used as a source of reinforcement of polymers, the major portion of these residues is currently burnt for energy supply in the sugar and alcohol industries and as a result of its burning, tons of ashes are produced. Due to the inorganic composition, ashes can be used as reinforcement in polymeric materials. This study presents the preparation and characterization of a composite based on HDPE matrix and sugarcane bagasse ashes as reinforcement cross-linked by electron-beam radiation. The HDPE /Ash composite (95:5 wt %) was obtained by using a twin-screw extruder machine followed by injection molding. After extrusion and injection molding process, the composites were subjected to electron-beam radiation, at radiation doses of 150 kGy and 250 kGy using a Dynamitron electron beam accelerator, at room temperature in the presence of air. The irradiated and non-irradiated composite specimens were characterization by tensile and MFI tests, scanning electron microscopy (SEM), X-ray diffraction (XRD) and sol-gel analysis. In addition, ash from bagasse fiber was characterized by WDXRF. (author)

  15. Sugarcane bagasse ash reinforced HDPE composites: effects of electron-beam radiation crosslinking on tensile and morphological properties

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Jaciele G.; Gomes, Michelle G.; Oliveira, Rene R.; Silva, Valquiria A.; Sartori, Mariana M.; Ortiz, Angel V.; Moura, Esperidiana A.B., E-mail: jacielegteixeira@yahoo.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Environmental issues have led to the development of polymeric materials reinforced with fibers originated from renewable agricultural sources such as pineapple leaf, sisal, jute, piassava, coir, and sugarcane bagasse. Although sugarcane bagasse fiber residues has been extensively studied and used as a source of reinforcement of polymers, the major portion of these residues is currently burnt for energy supply in the sugar and alcohol industries and as a result of its burning, tons of ashes are produced. Due to the inorganic composition, ashes can be used as reinforcement in polymeric materials. This study presents the preparation and characterization of a composite based on HDPE matrix and sugarcane bagasse ashes as reinforcement cross-linked by electron-beam radiation. The HDPE /Ash composite (95:5 wt %) was obtained by using a twin-screw extruder machine followed by injection molding. After extrusion and injection molding process, the composites were subjected to electron-beam radiation, at radiation doses of 150 kGy and 250 kGy using a Dynamitron electron beam accelerator, at room temperature in the presence of air. The irradiated and non-irradiated composite specimens were characterization by tensile and MFI tests, scanning electron microscopy (SEM), X-ray diffraction (XRD) and sol-gel analysis. In addition, ash from bagasse fiber was characterized by WDXRF. (author)

  16. Three Point Bending of Top-Hat Stiffened Chopped Short Fibre Ramie/HDPE Thermoplastic Composite Beam

    Science.gov (United States)

    Hadi, Bambang K.; Nuril, Yogie S.

    2018-04-01

    The use of natural fibre and thermoplastic matrices in composite materials increased significantly during the last decade especially in the automotive industries. Ramie is one of these potential natural fibres. In this paper, a three point bending of top-hat beam made of ramie/HDPE (High-Density-Polyethylene) composites was performed. Top-hat stiffened structures were common structures found in the aerospace industries. Nevertheless, these structures are beginning to be applied in automotive structures in the forms of chassis and bumpers. The ramie/HDPE composite was manufactured using hot-press technique. The temperature was set to be 135°C and the pressure was 6 bars. Chopped short ramie fibre was used, due to good drape ability characteristics. The experiments showed that the beams produced a large non-linearity. Linear Finite Element Analysis was carried out to be compared with the experimental data. The differences are reasonable.

  17. Radiation cured coatings for fiber optics

    International Nuclear Information System (INIS)

    Ketley, A.D.; Morgan, C.R.

    1978-01-01

    A continuous protective coating is formed on a fiber optic by coating the fiber optic in a bath of a liquid radiation curable composition at a temperature up to 90 0 C and exposing the coated conductor to ultraviolet or high energy ionizing radiation to cure the coating

  18. Influence of light curing source on microhardness of composite resins of different shades Influência da fonte de luz polimerizadora na microdureza da resina composta de diferentes cores

    Directory of Open Access Journals (Sweden)

    André Luiz Fraga Briso

    2006-01-01

    Full Text Available INTRODUCTION: The evolution of light curing units can be noticed by the different systems recently introduced. The technology of LED units promises longer lifetime, without heating and with production of specific light for activation of camphorquinone. However, further studies are still required to check the real curing effectiveness of these units. PURPOSE: This study evaluated the microhardness of 4 shades (B-0.5, B-1, B-2 and B-3 of composite resin Filtek Z-250 (3M ESPE after light curing with 4 light sources, being one halogen (Ultralux - Dabi Atlante and three LED (Ultraled - Dabi Atlante, Ultrablue - DMC and Elipar Freelight - 3M ESPE. METHODS: 192 specimens were distributed into 16 groups, and materials were inserted in a single increment in cylindrical templates measuring 4mm x 4mm and light cured as recommended by the manufacturer. Then, they were submitted to microhardness test on the top and bottom aspects of the cylinders. RESULTS: The hardness values achieved were submitted to analysis of variance and to Tukey test at 5% confidence level. It was observed that microhardness of specimens varied according to the shade of the material and light sources employed. The LED appliance emitting greater light intensity provided the highest hardness values with shade B-0.5, allowing the best curing. On the other hand, appliances with low light intensity were the least effective. It was also observed that the bottom of specimens was more sensitive to changes in shade. CONCLUSION: Light intensity of LED light curing units is fundamental for their good functioning, especially when applied in resins with darker shades.INTRODUCTION: A evolução dos aparelhos fotopolimerizadores pode ser notada nos diferentes sistemas introduzidos recentemente no mercado. A tecnologia apresentada pelos aparelhos LED promete maior tempo de vida útil, não gerar aquecimento e produzir luz específica para a ativação da canforoquinona. No entanto, ainda são necess

  19. Radiation curing of intelligent coating for controlled release and permeation

    International Nuclear Information System (INIS)

    Nakayama, Hiroshi; Kaetsu, Isao; Uchida, Kumao; Sakata, Shoei; Tougou, Kazuhide; Hara, Takamichi; Matsubara, Yoshio

    2002-01-01

    Intelligent membranes for pH and temperature-responsive drug releases were developed by coating and curing of polymer-drug composite film with electrolyte or N-isopropyl acrylamide curable mixture. It was proved that those intelligent membranes showed the stimule-sensitive and responsive release functions and could be produced efficiently by radiation curing processing with a conveyer system

  20. Preparation of temperature responsive fragrance release membranes by UV curing

    International Nuclear Information System (INIS)

    Nakayama, Hiroshi; Kaetsu, Isao; Uchida, Kumao; Okuda, Jyunya; Kitami, Toshiaki; Matsubara, Yoshio

    2003-01-01

    The authors have studied the preparation and the function of intelligent drug release membranes by UV curing. Temperature responsive fragrance release membranes were prepared by UV curing process and the release functions were investigated as the function of thickness and composition of membrane. Microscopic observations were used to prove the postulated release mechanism

  1. Preparation and characterization of electron-beam treated HDPE composites reinforced with rice husk ash and Brazilian clay

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, A.V., E-mail: angelortiz@ipen.br [Nuclear and Energy Research Institute, IPEN-CNEN/SP Av. Prof. Lineu Prestes 2242, São Paulo, SP 05508-000 (Brazil); Teixeira, J.G.; Gomes, M.G.; Oliveira, R.R. [Nuclear and Energy Research Institute, IPEN-CNEN/SP Av. Prof. Lineu Prestes 2242, São Paulo, SP 05508-000 (Brazil); Díaz, F.R.V. [Metallurgical and Materials Engineering Department, Polytechnic School, University of São Paulo Av. Prof. Mello de Morais 2463, São Paulo, SP 05508-900 (Brazil); Moura, E.A.B. [Nuclear and Energy Research Institute, IPEN-CNEN/SP Av. Prof. Lineu Prestes 2242, São Paulo, SP 05508-000 (Brazil)

    2014-08-15

    Highlights: • We examine changes in HDPE properties when waste and clay are used as reinforcement. • The addition of only 3% of clay leads to important gains in HDPE properties. • The use of electron-beam contributes to greater improvements in material properties. • We observe 85% of cross-linking degree for the HDPE when treated with e-beam. - Abstract: This work evaluates the morphology, mechanical and thermo-mechanical properties of high density polyethylene (HDPE) composites. HDPE reinforced with rice husk ashes (80:20 wt%), HDPE reinforced with clay (97:3 wt%) and HDPE reinforced with both rice husk ashes and clay(77:20:3 wt%) were obtained. The Brazilian bentonite chocolate clay was used in this study. This Brazilian smectitic clay is commonly used to produce nanocomposites. The composites were produced by melting extrusion process and then irradiation was carried out in a 1.5 MeV electron-beam accelerator (room temperature, presence of air). Comparisons using the irradiated and non-irradiated neat polymer, and the irradiated and non-irradiated composites were made. The materials obtained were submitted to tensile, flexural and impact tests. Additionally HDT, SEM and XRD analyses were carried out along with the sol–gel analysis which aimed to assess the cross-linking degree of the irradiated materials. Results showed great improvement in most HDPE properties and a high cross-linking degree of 85% as a result of electron-beam irradiation of the material.

  2. Radiation curable adhesive compositions and composite structures

    International Nuclear Information System (INIS)

    Brenner, W.

    1984-01-01

    This disclosure relates to novel adhesive compositions and composite structures utilizing the same, wherein said adhesive compositions contain an elastomer, a chemically compatible ethylenically unsaturated monomer, a tackifier, an adhesion promoter, and optionally, pigments, fillers, thickeners and flow control agents which are converted from the liquid to the solid state by exposure to high energy ionizing radiation such as electron beam. A particularly useful application for such adhesive compositions comprises the assembly of certain composite structures or laminates consisting of, for example, a fiber flocked rubber sheet and a metal base with the adhesive fulfilling the multiple functions of adhering the flocked fiber to the rubber sheet as well as adhering the rubber sheet to the metal base. Optionally, the rubber sheet itself may also be cured at the same time as the adhesive composition with all operations being carried out at ambient temperatures and in the presence of air, with exposure of said assembly to selected dosages of high energy ionizing radiation. These adhesive compositions contain no solvents thereby almost eliminating air pollution or solvent toxicity problems, and offer substantial savings in energy and labor as they are capable of curing in very short time periods without the use of external heat which might damage the substrate

  3. A comparative evaluation of effect of modern-curing lights and curing modes on conventional and novel-resin monomers

    Science.gov (United States)

    Roy, Konda Karthik; Kumar, Kanumuru Pavan; John, Gijo; Sooraparaju, Sujatha Gopal; Nujella, Surya Kumari; Sowmya, Kyatham

    2018-01-01

    Aim: The aim of this study is to compare and to evaluate effect of curing light and curing modes on the nanohybrid composite resins with conventional Bis-GMA and novel tricyclodecane (TCD) monomers. Methodology: Two nanohybrid composites, IPS empress direct and charisma diamond were used in this study. Light-emitting diode (LED)-curing unit and quartz-tungsten-halogen (QTH)-curing unit which were operated into two different modes: continuous and soft start. Based on the composite resin, curing lights, and mode of curing used, the samples were divided into 8 groups. After polymerization, the samples were stored for 48 h in complete darkness at 37°C and 100% humidity. The Vickers hardness (VK) of the surface was determined with Vickers indenter by the application of 200 g for 15 s. Three VK readings were recorded for each sample surface both on top and bottom surfaces. For all the specimens, the three hardness values for each surface were averaged and reported as a single value. The mean VK and hardness ratio were calculated. The depth of cure was assessed based on the hardness ratio. Results: Comparison of mean hardness values and hardness ratios was done using ANOVA with post hoc Tukey's test. Conclusion: Both QTH- and LED-curing units had shown the adequate depth of cure. Soft-start-curing mode in both QTH- and LED-curing lights had effectively increased microhardness than the continuous mode of curing. TCD monomer had shown higher hardness values compared with conventional Bis-GMA-containing resin. PMID:29628651

  4. Method to measure composition modifications in polyethylene terephthalate during ion beam irradiation

    Science.gov (United States)

    Abdesselam, M.; Stoquert, J. P.; Chami, S.; Djebara, M.; Chami, A. C.; Siad, M.

    2009-01-01

    Matter losses of polyethylene terephthalate (PET, Mylar) films induced by 1600 keV deuteron beams have been investigated in situ simultaneously by nuclear reaction analysis (NRA), deuteron forward elastic scattering (DFES) and hydrogen elastic recoil detection (HERD) in the fluence range from 1 × 10 14 to 9 × 10 16 cm -2. Volatile degradation products escape from the polymeric film, mostly as hydrogen-, oxygen- and carbon-containing molecules. Appropriate experimental conditions for observing the composition and thickness changes during irradiation are determined. 16O(d,p 0) 17O, 16O(d,p 1) 17O and 12C(d,p 0) 13C nuclear reactions were used to monitor the oxygen and carbon content as a function of deuteron fluence. Hydrogen release was determined simultaneously by H(d,d)H DFES and H(d,H)d HERD. Comparisons between NRA, DFES and HERD measurements show that the polymer carbonizes at high fluences because most of the oxygen and hydrogen depletion has already occured below a fluence of 3 × 10 16 cm -2. Release curves for each element are determined. Experimental results are consistent with the bulk molecular recombination (BMR) model.

  5. Nonlinear saturation controller for vibration supersession of a nonlinear composite beam

    Energy Technology Data Exchange (ETDEWEB)

    Hamed, Y. S. [Menofia University, Menouf (Egypt); Amer, Y. A. [Zagazig University, Zagazig (Egypt)

    2014-08-15

    In this paper, a study for nonlinear saturation controller (NSC) is presented that used to suppress the vibration amplitude of a structural dynamic model simulating nonlinear composite beam at simultaneous sub-harmonic and internal resonance excitation. The absorber exploits the saturation phenomenon that is known to occur in dynamical systems with quadratic non-linearities of the feedback gain and a two-to-one internal resonance. The analytical solution for the system and the nonlinear saturation controller are obtained using method of multiple time scales perturbation up to the second order approximation. All possible resonance cases were extracted at this approximation order and studied numerically. The stability of the system at the worst resonance case (Ω = 2ω{sub s} and ω{sub s} =2ω{sub C}) is investigated using both frequency response equations and phase-plane trajectories. The effects of different parameters on the system and the controller are studied numerically. The effect of some types of controller on the system is investigated numerically. The simulation results are achieved using Matlab and Maple programs.

  6. Surface composite nanostructures of AZ91 magnesium alloy induced by high current pulsed electron beam treatment

    International Nuclear Information System (INIS)

    Li, M.C.; Hao, S.Z.; Wen, H.; Huang, R.F.

    2014-01-01

    High current pulsed electron beam (HCPEB) treatment was conducted on an AZ91 cast magnesium alloy with accelerating voltage 27 kV, energy density 3 J/cm 2 and pulse duration 2.5 μs. The surface microstructure was characterized by optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), and transmission electron microscope (TEM). The surface corrosion property was tested with electrochemical method in 3.5 wt.% NaCl solution. It is found that after 1 pulse of HCPEB treatment, the initial eutectic α phase and Mg 17 Al 12 particles started to dissolve in the surface modified layer of depth ∼15 μm. When using 15 HCPEB pulses, the Al content in surface layer increased noticeably, and the phase structure was modified as composite nanostructures consisted of nano-grained Mg 3.1 Al 0.9 domains surrounded by network of Mg 17 Al 12 phase. The HCPEB treated samples showed an improved corrosion resistance with cathodic current density decreased by two orders of magnitude as compared to the initial AZ91 alloy.

  7. Modelling the bending/bowing of composite beams such as nuclear fuel

    International Nuclear Information System (INIS)

    Tayal, M.

    1989-01-01

    Arrays of tubes are used in many engineered structures, such as in nuclear fuel bundles and in steam generators. The tubes can bend (bow) due to in-service temperatures and loads. Assessments of bowing of nuclear fuel elements can help demonstrate the integrity of fuel and of surrounding components, as a function of operating conditions such as channel power. The BOW code calculates the bending of composite beams such as fuel elements, due to gradients of temperature and due to hydraulic forces. The deflections and rotations are calculated in both lateral directions, for given conditions of temperatures. Wet and dry operation of the sheath can be simulated. BOW accounts for the following physical phenomena: circumferential and axial variations in the temperatures of the sheath and of the pellet; cracking of pellets; grip and slip between the pellets and the sheath; hydraulic drag; restraint from endplates, from neighbouring elements, and from the pressure-tube; gravity; concentric or eccentric welds between endcaps and endplate; neutron flux gradients; and variations of material properties with temperature. The code is based on fundamental principles of mechanics. The governing equations are solved numerically using the finite element method. Several comparisons with closed-form equations shoe that the solutions of BOW are accurate. BOW's predictions for initial in-reactor bow are also consistent with two post-irradiation measurements

  8. Evaluation of fiber’s misorientation effect on compliance and load carry capacity of shaped composite beams

    Science.gov (United States)

    Polilov, A. N.; Tatus’, N. A.

    2018-04-01

    The goal of this paper is analysis of design methods for composite beams and plates with curvilinear fiber trajectories. The novelty of this approach is determined by the fact that traditional composite materials are typically formed using prepregs with rectilinear fibers only. The results application area is associated with design process for shaped composite structure element by using of biomechanical principles. One of the related problems is the evaluation of fiber’s misorientation effect on stiffness and load carry capacity of shaped composite element with curvilinear fiber trajectories. Equistrong beam with constant cross-section area is considered as example, and it can be produced by unidirectional fiber bunch forming, impregnated with polymer matrix. Effective elastic modulus evaluation methods for structures with curvilinear fiber trajectories are validated. Misorientation angle range (up to 5o) when material with required accuracy can be considered as homogeneous, neglecting fiber misorientation, is determined. It is shown that for the beams with height-to-width ratio small enough it is possible to consider 2D misorientation only.

  9. A comparative study for different shielding material composition and beam geometry applied to PET facilities: simulated transmission curves

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, Gabriela [Pontificia Univ. Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil). Grupo de Experimentacao e Simulacao Computacional em Fisica Medica; Costa, Paulo Roberto, E-mail: pcosta@if.usp.br [Universidade de Sao Paulo (IF/USP), SP (Brazil). Dept. de Fisica Nuclear. Lab. de Dosimetria das Radiacoes e Fisica Medica

    2013-03-15

    The aim of this work is to simulate transmission data for different beam geometry and material composition in order to evaluate the effect of these parameters on transmission curves. The simulations are focused on outgoing spectra for shielding barriers used in PET facilities. The behavior of the transmission was evaluated as a function of the shielding material composition and thickness using Geant4 Monte Carlo code, version 9.2 p 03.The application was benchmarked for barited mortar and compared to The American Association of Physicists in Medicine (AAPM) data for lead. Their influence on the transmission curves as well the study of the influence of the shielding material composition and beam geometry on the outgoing spectra were performed. Characteristics of transmitted spectra, such as shape, average energy and Half-Value Layer (HVL), were also evaluated. The Geant4 toolkit benchmark for the energy resulting from the positron annihilation phenomena and its application in transmission curves description shown good agreement between data published by American Association on Physicists in Medicine task group 108 and experimental data published by Brazil. The transmission properties for different material compositions were also studied and have shown low dependency with the considered thicknesses. The broad and narrow beams configuration presented significant differences on the result. The fitting parameter for determining the transmission curves equations, according to Archer model is presented for different material. As conclusion were defined that beam geometry has significant influence and the composition has low influence on transmission curves for shielding design for the range of energy applied to PET. (author)

  10. A comparative study for different shielding material composition and beam geometry applied to PET facilities: simulated transmission curves

    International Nuclear Information System (INIS)

    Hoff, Gabriela; Costa, Paulo Roberto

    2013-01-01

    The aim of this work is to simulate transmission data for different beam geometry and material composition in order to evaluate the effect of these parameters on transmission curves. The simulations are focused on outgoing spectra for shielding barriers used in PET facilities. The behavior of the transmission was evaluated as a function of the shielding material composition and thickness using Geant4 Monte Carlo code, version 9.2 p 03.The application was benchmarked for barited mortar and compared to The American Association of Physicists in Medicine (AAPM) data for lead. Their influence on the transmission curves as well the study of the influence of the shielding material composition and beam geometry on the outgoing spectra were performed. Characteristics of transmitted spectra, such as shape, average energy and Half-Value Layer (HVL), were also evaluated. The Geant4 toolkit benchmark for the energy resulting from the positron annihilation phenomena and its application in transmission curves description shown good agreement between data published by American Association on Physicists in Medicine task group 108 and experimental data published by Brazil. The transmission properties for different material compositions were also studied and have shown low dependency with the considered thicknesses. The broad and narrow beams configuration presented significant differences on the result. The fitting parameter for determining the transmission curves equations, according to Archer model is presented for different material. As conclusion were defined that beam geometry has significant influence and the composition has low influence on transmission curves for shielding design for the range of energy applied to PET. (author)

  11. Development and Application of an Acoustic Waveguide Technology to in-Process Cure and in-Service Dynamic Response Monitoring of Liquid Molded Composite Armor Smart Structures

    National Research Council Canada - National Science Library

    Li, Yan

    1997-01-01

    ...) structural dynamic responses and damages after the part is placed in service. The sensor has a low profile and is embedded in the composites manufactured through processes such as Resin Transfer Molding (RTM...

  12. Solid-state /sup 13/C NMR study of cured resorcinol-formaldehyde resins

    Energy Technology Data Exchange (ETDEWEB)

    Lippmaa, H.; Samoson, A.

    1988-08-01

    The curing process generally follows the pattern observed in the stage of prepolymer formation. Catalysts (NaOH, hexa, Mg(OCOCH/sub 3/)/sub 2/) that have no substantial influence on the isomeric composition of the resorcinol-formaldehyde prepolymers, do not affect the isomeric composition of the cured resins to any significant extent either. Isomeric composition of the cured resins depends mostly on the presence of water during the curing process, necessary for depolymerisation of the added paraformaldehyde. Curing in the melt leads to enhanced 2-substitution in the 1,3-dihydroxybenzene rings. In the /sup 13/C NMR spectra of cured powdered samples, the tendency of 5-methylresorcinol to form oligomers with a higher degree of 2-substitution than resorcinol is clearly apparent. Polycondensation process continues in the powdered resins after initial curing until complete consumption of all formaldehyde. Curing of phenol-formaldehyde resols proceeds through intermediate dimethylene ether formation.

  13. Comparative analysis of the influence of creep of concrete composite beams of steel - concrete model based on Volterra integral equation

    Directory of Open Access Journals (Sweden)

    Partov Doncho

    2017-01-01

    Full Text Available The paper presents analysis of the stress-strain behaviour and deflection changes due to creep in statically determinate composite steel-concrete beam according to EUROCODE 2, ACI209R-92 and Gardner&Lockman models. The mathematical model involves the equation of equilibrium, compatibility and constitutive relationship, i.e. an elastic law for the steel part and an integral-type creep law of Boltzmann - Volterra for the concrete part considering the above mentioned models. On the basis of the theory of viscoelastic body of Maslov-Arutyunian-Trost-Zerna-Bažant for determining the redistribution of stresses in beam section between concrete plate and steel beam with respect to time 't', two independent Volterra integral equations of the second kind have been derived. Numerical method based on linear approximation of the singular kernel function in the integral equation is presented. Example with the model proposed is investigated.

  14. Modelling of ultrasonic beam propagation from an array through transversely isotropic fibre reinforced composites using Multi Gaussian beams

    NARCIS (Netherlands)

    Anand, C.; Shroff, S.; Groves, R.M.; Benedictus, R.

    2017-01-01

    Ultrasonic arrays are used for non-destructive evaluation of structures for aerospace and other applications. With the increase in the usage of fibre-reinforced composites in aerospace structures, this evaluation becomes complex due to the effects of attenuation and reflection from the layer

  15. Assessment of environmental impact of ultraviolet radiation or electron beam cured print inks on plastic packaging materials; Avaliacao do impacto ambiental gerado por tintas graficas curadas por radiacao ultravioleta ou feixe de eletrons em materiais para embalagens plasticas convencionais ou biodegradaveis pos-consumo

    Energy Technology Data Exchange (ETDEWEB)

    Bardi, Marcelo Augusto Goncalves

    2014-07-01

    The high level of pollution generated by the inadequate disposal of polymeric materials has motivated the search for environmentally friendly systems and techniques such as the application of biodegradable polymers and the replacement of the solvent-based paint systems by those with high solids content, based water or cured by radiation, practically free of volatile organic compounds. However, the cured polymer coatings are neither soluble nor molten, increasing the complexity of the reprocessing, recycling and degradation. Thus, this work aimed to develop print inks modified with pro-degrading agents, cured by ultraviolet radiation or electron beam, for printing or decoration in plastic packaging products of short lifetime, which are biodegradable or not. Six coatings (varnish and inks in five colors: yellow, blue, white, black and red), three pro-degrading agents (cobalt stearate, cerium stearate and manganese stearate), five polymeric substrates (Ecobras®, low density polyethylene and its respective modifications with pro-degrading agents). The coatings were applied to the substrates and cured by ultraviolet radiation or electron beam, resulting in 180 samples. These materials were then exposed to accelerated aging chamber, type 'QUV', and composting in natural environment. In order to assess the effects of the polymer coatings on the degradation process of the specimens, only the yellow and black samples were exposed to a controlled composting environment via respirometry, reducing to 16 the number of samples. The organic compound generated by the biodegradation process was analyzed by the ecotoxicity tests. It was observed that the coating layer acted as a barrier that inhibits degradation of the plastic when exposed to weathering. The addition of pro-degrading agents promoted acceleration in the degradation process, promoting the migration of the metal ion to the medium without affecting the final quality of the organic compost. (author)

  16. Self-healing woven glass fabric/epoxy composites with the healant consisting of micro-encapsulated epoxy and latent curing agent

    International Nuclear Information System (INIS)

    Yin Tao; Zhou Lin; Rong Minzhi; Zhang Mingqiu

    2008-01-01

    This paper reports a study of self-healing woven glass fabric reinforced epoxy composites. The healing agent was a two-component one synthesized in the authors' laboratory, which consisted of epoxy-loaded urea-formaldehyde microcapsules as the polymerizable binder and CuBr 2 (2-methylimidazole) 4 (CuBr 2 (2-MeIm) 4 ) as the latent hardener. Both the microcapsules and the matching catalyst were pre-embedded and pre-dissolved in the composites' matrix, respectively. When the microcapsules are split by propagating cracks, the uncured epoxy can be released into the damaged areas and then consolidated under the catalysis of CuBr 2 (2-MeIm) 4 that was homogeneously distributed in the composites' matrix on a molecular scale. As a result, the cracked faces can be bonded together. The influence of the content of the self-healing agent on the composites' tensile properties, interlaminar fracture toughness and healing efficiency was evaluated. It was found that a healing efficiency over 70% relative to the fracture toughness of virgin composites was obtained in the case of 30 wt% epoxy-loaded microcapsules and 2 wt% latent hardener

  17. To improve impact damage response of single and multi-delaminated FRP composites using natural Flax yarn

    International Nuclear Information System (INIS)

    Ghasemnejad, H.; Soroush, V.R.; Mason, P.J.; Weager, B.

    2012-01-01

    Highlights: ► To study the impact resistance of delaminated composite structures. ► To improve the impact resistance of delaminated composite structures using natural Flax yarn. ► To investigate the effect of z-pinning on the damage process of composite materials. ► To develop FE techniques to model the impact process of composite structures using LSDYNA. -- Abstract: The ply delamination which is known as a principle mode of failure of layered composites due to separation along the interfaces of the layers is one of the main concerns in designing of composite material structures. In this regard, the effect of hybrid laminate lay-up in multi-delaminated composite beam was investigated. The Charpy impact test was chosen to study the energy absorbing capability of delaminated composite beam. Hybrid composite beams were fabricated from combination of glass/epoxy and carbon/epoxy composites. To improve the impact behaviour of multi-delaminated composite beams the laminated hybrid composite beams were pinned using Flax yarns before curing process. It was shown that the multi-delaminated composite beams which are pinned in z-direction are able to arrest the crack propagation and consequently absorb more energy in comparison with simple ones in hybrid composite beams. The Charpy impact test of delaminated composite beams was also simulated by finite element software LS-DYNA and the results were verified with the relevant experimental results.

  18. Structural and composition investigations at delayered locations of low k integrated circuit device by gas-assisted focused ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dandan, E-mail: dandan.wang@globalfoundries.com; Kee Tan, Pik; Yamin Huang, Maggie; Lam, Jeffrey; Mai, Zhihong [Technology Development Department, GLOBALFOUNDRIES Singapore Pte. Ltd., 60 Woodlands Industrial Park D, Street 2, Singapore 738406 (Singapore)

    2014-05-15

    The authors report a new delayering technique – gas-assisted focused ion beam (FIB) method and its effects on the top layer materials of integrated circuit (IC) device. It demonstrates a highly efficient failure analysis with investigations on the precise location. After removing the dielectric layers under the bombardment of an ion beam, the chemical composition of the top layer was altered with the reduced oxygen content. Further energy-dispersive x-ray spectroscopy and Fourier transform infrared analysis revealed that the oxygen reduction lead to appreciable silicon suboxide formation. Our findings with structural and composition alteration of dielectric layer after FIB delayering open up a new insight avenue for the failure analysis in IC devices.

  19. Electron beam synthesis of silica/nano silver composite and its application in controlling microorganisms in drinking water

    International Nuclear Information System (INIS)

    Ramnani, S.P.; Biswal, Jayashree; Sabharwal, S.; Rama Rao, K.C.; Sai Prasad, P.

    2008-01-01

    Silica/nano silver composites were prepared by electron beam (EB) irradiation technique. The solution containing silica nanoparticles and AgNO 3 in various proportion were subjected to EB irradiation. The EB dose delivered was such that all the Ag + is converted into metallic silver. The samples were characterized by XRD, SEM and TEM analysis. The composites were tested for their anti microbial activity in water samples. The results indicated that there is an optimum size of Ag nanoparticles that shows better antimicrobial activity. (author)

  20. Composition and stratigraphy of the paint layers: investigation on the Madonna dei Fusi by ion beam analysis techniques

    Science.gov (United States)

    Grassi, N.

    2005-06-01

    In the framework of the extensive study on the wood painting "Madonna dei fusi" attributed to Leonardo da Vinci, Ion Beam Analysis (IBA) techniques were used at the Florence accelerator laboratory to get information about the elemental composition of the paint layers. After a brief description of the basic principle and the general features of IBA techniques, we will illustrate in detail how the analysis allowed us to characterise the pigments of original and restored areas and the substrate composition, and to obtain information about the stratigraphy of the painting, also providing an estimate of the paint layer thickness.

  1. Effect of pasture on chestnut or acorn on fatty acid composition and aromatic profile of fat of Cinta Senese dry-cured ham

    Directory of Open Access Journals (Sweden)

    Franci, Oreste

    2009-07-01

    Full Text Available The objective of this study was to evaluate the effect of pasture on oak and chestnut grove on chemical and aromatic traits of Cinta Senese cured ham. Fifteen Cinta Senese barrows (124 kg of l.w. on average were allotted to three groups: one group (MI was reared outdoors in confined area and fed commercial feedstuff. The other two groups were raised under free-range conditions on acorn (AC or chestnut (CH woods. At slaughtering (148 kg of l.w. the right thighs were seasoned for 360 days, on average, to obtained cured hams. Results demonstrated that subcutaneous fat of ham of CH and AC groups, respect to CONC group, was the richest in MUFA (51.3 and 53.9 vs 49.5% respectively, because of the higher content of oleic acid (48.4 and 50.8 vs 46.2%, respectively. AC showed a lower percentage of PUFA than CH and CONC (13.8 vs 15.4 and 16.3%, respectively. As regard volatile compounds, AC, respect to CH and MI groups, showed the highest value of aldehydes (44.1 vs 30.3 and 33.5% respectively and ethers (4.04 vs 1.15 and 1.71% respectively.El objetivo de este estudio fue la evaluación de la composición de los ácidos grasos y de los compuestos volátiles del jamón curado Toscano obtenido de cerdos Cinta Senese alimentados con bellota, castaña o pienso. Quince cerdos de raza Cinta Senese fueron criados en extensivo: 5 fueron criados en bosque de bellota (AC, 5 en bosque de castaña (CH y 5 en un cercado y alimentados con pienso (MI. El día posterior al sacrificio se curaron los jamones. La composición de los ácidos grasos fue estadísticamente diferente entre los tipos de alimentación. La grasa de AC presentó el mayor porcentaje de AGMI total en comparación con CH y MI (51.3 y 53.9 vs 49.5% respectivamente gracias al mayor porcentaje de ácido oleico (48.4 y 50.8 vs 46.2%, respectivamente, y la menor de AGPI total (13.8 vs 15.4 y 16.3%, respectivamente. En relación a los compuestos volátiles, la grasa de AC, en comparación con CH y MI

  2. Comparison of Film Thickness of Two Commercial Brands of Glass lonomer Cement and One Dual-cured Composite: An in vitro Study.

    Science.gov (United States)

    Khajuria, Rajat R; Singh, Rishav; Barua, Pranamee; Hajira, Nausheen; Gupta, Naveen; Thakkar, Rohit R

    2017-08-01

    The present study is undertaken to examine the film thickness of three most commonly used luting cements and to determine their usage as a luting agent. This study was carried out strictly according to the guidelines of American Dental Association (ADS) specification no. 8. Two glass slabs of 5 cm in length and 2 cm in width were used. One glass slab was kept over the other glass slab and the space between the two glass slabs was measured using metallurgical microscope at the power of 10*. Two brands of glass ionomer cement (GIC) and one dual-cured resin cement were used in this study. The test cement is sandwiched between two glass slabs. A static load of 15 kg was applied using universal testing machine on the glass slabs for 1 hour and the space present between the two glass slabs was measured using metallurgical microscope at the power of 10*. Greatest film thickness was found in group III (Paracore) followed by group II (micron) and lowest in group I (GC luting and lining cement). All the tested samples can be used for luting purposes. Greatest film thickness was observed in Paracore followed by micron and lowest in GC luting and lining cement. This suggests that the 25 to 27°C is ideal for mixing of the cement when used for luting consistency. The cement with film thickness more than 30 urn should never be used for luting purposes. The dentist should choose the luting cement with utmost care noting the film thickness and bond strength of the cement. The cement with low exothermic heat production and good bond strength should be encouraged.

  3. Imaging the interphase of carbon fiber composites using transmission electron microscopy: Preparations by focused ion beam, ion beam etching, and ultramicrotomy

    Directory of Open Access Journals (Sweden)

    Wu Qing

    2015-10-01

    Full Text Available Three sample preparation techniques, focused ion beam (FIB, ion beam (IB etching, and ultramicrotomy (UM were used in comparison to analyze the interphase of carbon fiber/epoxy composites using transmission electron microscopy. An intact interphase with a relatively uniform thickness was obtained by FIB, and detailed chemical analysis of the interphase was investigated by electron energy loss spectroscopy. It shows that the interphase region is 200 nm wide with an increasing oxygen-to-carbon ratio from 10% to 19% and an almost constant nitrogen-to-carbon ratio of about 3%. However, gallium implantation of FIB tends to hinder fine structure analysis of the interphase. For IB etching, the interphase region is observed with transition morphology from amorphous resin to nano-crystalline carbon fiber, but the uneven sample thickness brings difficulty for quantitative chemical analysis. Moreover, UM tends to cause damage and/or deformation on the interphase. These results are meaningful for in-depth understanding on the interphase characteristic of carbon fiber composites.

  4. Curing the queue

    NARCIS (Netherlands)

    Zonderland, Maartje Elisabeth

    2012-01-01

    In this dissertation we study several problems related to the management of healthcare and the cure of disease. In each chapter a hospital capacity distribution problem is analyzed using techniques from operations research, also known as mathematical decision theory. The problems considered are

  5. Radiation cured silicone rubber articles

    International Nuclear Information System (INIS)

    DuPont, J.G.; Goodwin, P.A.

    1984-01-01

    A process for making radiation cured silicone rubber articles is disclosed wherein a hydroxyl-terminated polysilaxane having a molecular weight from about 50,000 to about 2,000,000, optionally modified by mixing with up to 85% of an end-stopped silicone rubber, is mixed with from about 10 to about 70 parts per hundred of rubber of a finely divided silica filler with a particle size in the reinforcing range and other inert fillers as determined by desired final properties; the composition so prepared is formed into the desired shape at room temperature; the article so formed is precured to improve the mechanical properties of the material with which it is made by exposure to ammonia gas, ammonium hydroxide, or to the vapors or solutions of a volatile amine at room temperature; and the precured article is irradiated with high energy electrons or gamma radiation to effect a permanent cure of the material from which the article is formed

  6. Pretreatment of Woven Jute FRP Composite and Its Use in Strengthening of Reinforced Concrete Beams in Flexure

    Directory of Open Access Journals (Sweden)

    Tara Sen

    2013-01-01

    Full Text Available Environmental awareness motivates researchers worldwide to perform studies of natural fibre reinforced polymer composites, as they come with many advantages and are primarily sustainable. The present study aims at evaluating the mechanical characteristics of natural woven jute fibre reinforced polymer (FRP composite subjected to three different pretreatments, alkali, benzyl chloride, and lastly heat treatment. It was concluded that heat treatment is one of the most suitable treatment methods for enhancing mechanical properties of jute FRP. Durability studies on Jute FRP pertaining to some common environmental conditions were also carried out such as effect of normal water and thermal aging on the tensile strength of jute FRP followed by fire flow test. The heat treated woven jute FRP composites were subsequently used for flexural strengthening of reinforced concrete beams in full and strip wrapping configurations. The study includes the effect of flexural strengthening provided by woven jute FRP, study of different failure modes, load deflection behavior, effect on the first crack load, and ultimate flexural strength of concrete beams strengthened using woven jute FRP subjected to bending loads. The study concludes that woven jute FRP is a suitable material which can be used for flexural upgradation of reinforced concrete beams.

  7. Innovative Chemical Process for Recycling Thermosets Cured with Recyclamines® by Converting Bio-Epoxy Composites in Reusable Thermoplastic—An LCA Study

    Directory of Open Access Journals (Sweden)

    Angela D. La Rosa

    2018-02-01

    Full Text Available An innovative recycling process for thermoset polymer composites developed by Connora Technologies (Hayward, CA, USA was studied. The process efficacy has already been tested, and it is currently working at the plant level. The main aspect investigated in the present paper was the environmental impact by means of the Life Cycle Assessment (LCA method. Because of the need to recycle and recover materials at their end of life, the Connora process creates a great innovation in the market of epoxy composites, as they are notoriously not recyclable. Connora Technologies developed a relatively gentle chemical recycling process that induces the conversion of thermosets into thermoplastics. The LCA demonstrated that low environmental burdens are associated with the process itself and, furthermore, impacts are avoided due to the recovery of the epoxy-composite constituents (fibres and matrix. A carbon fibre (CF epoxy-composite panel was produced through Vacuum Resin Transfer Moulding (VRTM and afterwards treated using the Connora recycling process. The LCA results of both the production and the recycling phases are reported.

  8. Compositional and structural studies of ion-beam modified AlN/TiN multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Amati, M., E-mail: matteo.amati@elettra.eu [Elettra – Sincrotrone Trieste SCpA,Area Science Park, 34149, Trieste (Italy); Gregoratti, L.; Sezen, H. [Elettra – Sincrotrone Trieste SCpA,Area Science Park, 34149, Trieste (Italy); Grce, A.; Milosavljević, M. [VINČA Institute of Nuclear Sciences, Belgrade University, P.O. Box 522, 11001, Belgrade (Serbia); Homewood, K.P. [Materials Research Institute and School of Physics and Astronomy, Queen Mary University of London, Mile End Road, E1 4NS, London (United Kingdom)

    2017-07-31

    Highlights: • Inter-layer mixing, atomic redistribution, structural change, and phase transformation on AlN/TiN multilayers via argon ion irradiation. • Severe modifications are observed with TEM studies on highly immiscible alternating layers without any side effects such as beam heating. • The original TiN layers appear to grow in thickness by consuming the adjacent AlN layers, while obtaining a better TiAlN fcc crystalline structure. • Photoemission spectroscopy/microscopy indicates a transformation into Al deficient ternary and highly homogeneous compounds on both layers. • These results can be interesting towards further development of radiation tolerant materials based on immiscible ceramic nanocomposites. - Abstract: This paper reports on compositional and structural modifications induced in coated AlN/TiN multilayers by argon ion irradiation. The initial structure consisting of totally 30 alternate AlN (8 nm thick) and TiN (9.3 nm thick) layers was deposited on Si (100) wafers, by reactive sputtering. Irradiation was done with 180 keV Ar{sup +} to a high dose of 8 × 10{sup 16} ions/cm{sup 2}, which introduces up to ∼10 at.% of argon species, and generates a maximum displacement per atom of 92 for AlN and 127 for TiN, around the projected ion range (109 ± 34 nm). Characterizations were performed by Rutherford backscattering spectrometry, spatially resolved x-ray photoelectron spectroscopy, and transmission electron microscopy. The obtained results reveal that this highly immiscible and thermally stable system suffered a severe modification upon the applied ion irradiation, although it was performed at room temperature. They illustrate a thorough inter-layer mixing, atomic redistribution, structural change and phase transformation within the affected depth. The original TiN layers appear to grow in thickness, consuming the adjacent AlN layers, while retaining the fcc crystalline structure. In the mostly affected region, the interaction proceeds

  9. Cure of skin cancer. Surgical cure of skin cancer

    International Nuclear Information System (INIS)

    Zikiryakhodjaev, D.Z.; Sanginov, D.R.

    2001-01-01

    In this chapter authors studied the cure of skin cancer in particular the surgical cure of skin cancer. They noted that surgical cure of skin cancer is remain one of the primary and most important methods in treatment of skin cancer

  10. Dielectric properties of ultraviolet cured poly(dimethyl siloxane) sub-percolative composites containing percolative amounts of multi-walled carbon nanotubes

    DEFF Research Database (Denmark)

    Goswami, Kaustav; Daugaard, Anders Egede; Skov, Anne Ladegaard

    2015-01-01

    becoming conductive. Ultrasonicated and dispersed MWCNTs were co-precipitated together with an excess of short chain alpha, omega-vinyl terminated PDMS with a deficient amount of thiol-crosslinker and a photoinitiator (2,2-dimethoxy-2-phenylacetophenone, DMPA) into MeOH. The entire mixture was UV......-dependent AC conductivity studies revealed that an increase in the sample temperature could explain the premature breakdown observed for those composites with higher MWCNT loading....

  11. Full-Scale Testing of Thermoplastic Composite I-Beams for Bridges

    Science.gov (United States)

    2017-06-01

    beams retained residual deformations after each load cycle. Therefore, a large capacity-reduction factor is advisable for future strength designs...3 Figure 3. Nominal beam dimensions (not to scale...Figure 39. Nominal dimension of machine-cut dog-bone tension specimens. .................. 43 Figure 40. Dog-bone specimen for tensile strength

  12. Rapid Strengthening of Full-Sized Concrete Beams with Powder-Actuated fastening Systems and Fiber-Reinforced Polymer (FRP) Composite Materials

    National Research Council Canada - National Science Library

    Bank, Lawrence

    2002-01-01

    A research study was conducted to determine if the method of retrofitting reinforced concrete beams with powder-actuated fasteners and composite materials was applicable to full-scale flexural members...

  13. Investigation on working quality of laser beam cutting of composite materials. Final report. Untersuchung der Bearbeitungsgenauigkeit und Prozessfuehrung beim Laserstrahlschneiden von Verbundwerkstoffen und Werkstoffverbunden. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Geiger, M.; Mueller, R.

    1992-01-01

    Expanded use of composite materials often requires a cutting process to reach the desired shape of the work piece. In conventional mechanical cutting technologies like milling remarcable tool wear has to be considered due to the containing glass fibers which have a tremendous abrasive effect on the tool teeth. Here the laser beam is an alternative 'tool'. With this investigations the knowledge about the parameters of laser beam cutting of composites which determine working quality was increased. Requirements for an optimal cutting process and fundamental correlations between process parameters and working quality are presented. In absence of suitable criterions to estimate the working quality of laser beam cut composite materials, a suggestion of a DIN 2310, Part 7, 'Thermal Cutting, Laser Beam Cutting of Composites' is presented. (orig.) With 69 refs., 125 figs.

  14. Radiation Processing of Advanced Composite Materials

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Phil Hyun; Jeun, Joonpyo; Nho, Young Chang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-04-15

    Advanced composites, such as carbon-fiber-reinforced plastics, are being used widely for many applications. Carbon fiber/epoxies composites have attracted special attention from the aircraft, aerospace, marine engineering, sporting goods and transportation industries, because they have useful mechanical properties including high strength-to-weight and stiffness-to-weight ratios, a corrosion resistant, impact and damage tolerance characteristics and wear properties. Thermal curing has been the dominant industrial process for advanced composites until now, however, a radiation curing process using UV, microwave x-ray, electron-beam(E-beam) and {gamma}-ray has emerged as a better alternative in recent years. These processes are compatible with the manufacturing of composites using traditional fabrication methods including a filament/tape winding, pultrusion, resin transfer moulding and hand lay-up. In this study, E-beam curable carbon fiber/epoxy composites were manufactured, and their mechanical properties were investigated. Two epoxy resins (bisphenol-A, bisphenol-F) containing photo-initiators (tri aryl sulfonium hexafluorophosphate, tri aryl sulfonium hexafluoroantimonate) were used as a matrix and a 4H-satin carbon woven fabric was used as a reinforcement. And then an electron beam irradiated the composites up to 200 kGy in a vacuum and an inert atmosphere. The cure cycle was optimized and the properties of composites were evaluated and analyzed via a differential scanning calorimetry, scanning electron microscopy, sol-gel extractions, FT-NIR, universal test machine, and an impact tester. The gel content, glass transition temperature and mechanical strength of the irradiated composites were increased with an increasing radiation dose.

  15. Recent advance and applications in radiation curing of coatings

    International Nuclear Information System (INIS)

    Kishi, Naoyuki

    1976-01-01

    The recent advance and application as well as the profitability of method of coating by curing with electron beam are reviewed. The acrylic prepolymers having two or more acryloyl radicals on side chains or at the end can be cured with electron beam, and have excellent characteristics. The technique to use acrylic esters and methacrylic esters as dilutant monomers has been developed. Mitsubishi Rayon Co., Ltd. is finishing asbestos slate boards and calcium silicate boards for prefabricated houses, utilizing an electron beam curing coating line. The line serves as a semicommercial production line having the capacity of continuously coating and curing boards of 1,200 mm by 2,400 mm. It is equipped with an electron beam accelerator of 500 kV x 65 mA (max. 100 mA), a conveyor running at speed of 5 to 100 m/min, and a curtain flow coater, a roller coater and the like. It can be cured rapidly at room temperature. The finished coatings have high cross-linking density and withstand particularly blocking, freezing and solvents. Its application to the coating of automotive parts by Suzuki Automobile Co. is briefly mentioned. (Iwakiri, K.)

  16. What is radiation curing

    International Nuclear Information System (INIS)

    Kinstle, J.F.

    1975-01-01

    Radiation curing is a highly interdisciplinary and sophisticated field. Successful interplay between chemists and engineers of various disciplines is required. Throughout the research-development-applications cycle, two disciplines for which hybridization is extremely important are radiation chemistry and polymer chemistry. The molecular level effects caused by absorbed radiation depend strongly on the type and intensity of the radiation. Efficient utilization of the radiation to effect desired transformations in a monomer and/or polymer system, and maximization of final properties, depend on well-planned polymer synthesis and system formulation. The elementary basis of these two disciplines and the manner in which they necessarily coalesce in the field of radiation curing are reviewed

  17. Simulation of Low Velocity Impact Induced Inter- and Intra-Laminar Damage of Composite Beams Based on XFEM

    Science.gov (United States)

    Sun, Wei; Guan, Zhidong; Li, Zengshan

    2017-12-01

    In this paper, the Inter-Fiber Fracture (IFF) criterion of Puck failure theory based on the eXtended Finite Element Method (XFEM) was implemented in ABAQUS code to predict the intra-laminar crack initiation of unidirectional (UD) composite laminate. The transverse crack path in the matrix can be simulated accurately by the presented method. After the crack initiation, the propagation of the crack is simulated by Cohesive Zoom Model (CZM), in which the displacement discontinuities and stress concentration caused by matrix crack is introduced into the finite element (FE) model. Combined with the usage of the enriched element interface, which can be used to simulate the inter-laminar delamination crack, the Low Velocity Impact (LVI) induced damage of UD composite laminate beam with a typical stacking of composite laminates [05/903]S is studied. A complete crack initiation and propagation process was simulated and the numerical results obtained by the XFEM are consistent with the experimental results.

  18. Distance to Cure

    OpenAIRE

    Capachi, Casey

    2013-01-01

    Distance to Cure A three-part television series by Casey Capachi www.distancetocure.com   Abstract   How far would you go for health care? This three-part television series, featuring two introductory segments between each piece, focuses on the physical, cultural, and political obstacles facing rural Native American patients and the potential of health technology to break down those barriers to care.   Part one,Telemedici...

  19. Evaluation of mechanical properties of Z250 composite resin light-cured by different methods Avaliação de propriedades mecânicas da resina composta Z250 fotoativada com diferentes métodos

    Directory of Open Access Journals (Sweden)

    Andresa Carla Obici

    2005-12-01

    Full Text Available This study evaluated some mechanical parameters of Z250 composite resin using different light-curing methods. Ten specimens were prepared for each mechanical test group with different dimensions according to the test. Light-curing was performed by: a. continuous light (800mW/cm²-40s; b. exponential light (0-800mW/cm²-40s; c. intermittent light (2s-600mW/cm²; 2s without light-80s; d. stepped light (10s-150mW/cm²; 30s-650mW/cm²; e. PAC (1320mW/cm²-3s; f. LED (350mW/cm²-40s. After 24 ± 1 h, the specimens were loaded at a crosshead speed of 0.5 mm/min until fracture. The mechanical properties were calculated and analyzed by ANOVA and Tukey test (5%. The results showed that the highest compressive strength values were found for the continuous, exponential, intermittent and stepped light methods, whereas PAC and LED obtained the lowest values. LED, stepped light, PAC, exponential and continuous light presented the highest values for diametral tensile strength. The intermittent light showed the lowest value, which was significantly lower than the value obtained for LED only. Flexural strength results were not significantly different between all light-curing methods. Finally, the highest modulus of elasticity values were obtained for LED, exponential, continuous and intermittent light, whereas PAC and stepped light showed the lowest values. The mechanical properties were affected by light-curing methods employed.Este estudo avaliou algumas propriedades mecânicas da resina composta Z250 usando diferentes métodos de fotoativação. Dez amostras foram preparadas para cada grupo, com diferentes dimensões de acordo com o ensaio. Os métodos de fotoativação foram: a luz contínua (800mW/cm²-40s; b luz exponencial (0-800mW/cm²-40s; c luz intermitente (2s-600mW/cm²; 2s sem luz-80s; d dupla intensidade (10s-150mW/cm²; 30s-650mW/cm²; e PAC (1320mW/cm²-3s; f LED (350mW/cm²-40s. Após 24 ± 1 h, as amostras foram carregadas até fraturar (v=0

  20. Finite element beam flexural properties of cement composites of fiber reinforced PVA

    Science.gov (United States)

    Yang, Chengzhi; Pei, Changchun

    2018-05-01

    In this paper, the initial cracking state and the mid span bending moment and deflection of ECC beam under different PVA fiber and fly ash mixing rate are studied by finite element simulation analysis. The results show that the bending moment of the ECC beam increases with the increase of the PVA fiber content, and the deflection decreases. When the ratio of PVA fiber is 1.5%, the middle bending moment is the largest and the deflection is the least. With the increase of fly ash content, the mid span bending moment of ECC beam increases first and then decreases. When the fly ash ratio is 60%, the middle bending moment is the largest and the deflection is the least. Through the study, the formula for calculating the flexural capacity of the cross section suitable for ECC beams is derived.