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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1891-1897 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Analytical studies using chemical, spectral, and chromatographic methods have been carried out for four commercial diglycidyl ether of bisphenol A (DGEBA) resins (AER, EER, DER, and NER) in order to evaluate the essential parameters of DGEBA for synthesizing 2,2-bis [4- (2-hydroxy-3-methacryloyloxypropoxy)] phenyl propane (BIS-GMA), an impportant precursor for dental composites. Parameters such as epoxy equivalent weight, hydroxyl value, and hydrolyzable chlorine content have been estimated. The role of these parameters in determining the final purity of BIS-GMA has also been discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 561-573 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The synthesis of bisphenol A-glycidyl methacrylate (BIS-GMA), the resin component in most dental composite restorative materials, catalyzed by different tertiary amine accelerators such as N,N′-dimethyl-p-toluidine (DMPT), N,N′-dimethylamino phenethyl alcohol (DMAPEA), and N,N′-dimethylamino ethyl methacrylate (DMAEMA) is reported in this work. The effect of varying concentrations of accelerators and the reaction conditions of the synthesis as a function of time is studied in detail. The kinetics of the reaction between epoxide and carboxyl group during the formation of BIS-GMA is monitored using infrared (IR) and chemical techniques. The reaction is found to follow first-order and zero-order kinetics with respect to epoxide and acid, respectively. The degree of epoxide and acid conversion has been calculated as a function of time. The percentages of various isomers, formed under different reaction conditions have been reported. Characterization procedures for BIS-GMA have been developed.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 981-990 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Plasticized PVC finds applications in a wide range of medical products. However, plasticizer leaching, known to take place from these conventional materials, is not desirable. A number of approaches to overcome this problem are mentioned in the literature. We suggest pursuing the polyblend approach. Plasticized PVC containing different amounts of plasticizer, binary polyblends of plasticized PVC (PPVC) with acrylonitrile-butadiene rubber (NBR1), and compounded graft polymer of vinyl chloride and ethylene-vinyl acetate copolymer (EVAPVC), and ternary blends of PPVC, NBR1, and EVAPVC, were formulated. In this article, we report our results of studies on water vapor, O2, CO2, and N2 permeabilities. Increased plasticization for PVC was found to increase permeability for water vapor, O2, CO2, and N2. Rise in temperature increased the permeability for water vapor and the change became faster as the materials crossed the region of Tg. A simple model suggested for permeability worked satisfactorily. The binary and ternary blends, based on PPVC, had lower O2, CO2, and N2 permeability. This improvement in property is of great practical significance and interest and the results indicate that PVC-based polyblends can be investigated further for potential applications in medicine
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 845-853 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Binary polyblends of plasticized poly(vinylchloride) (PPVC1) with acrylonitrile-butadiene rubber (NBR1), compounded graft polymer of vinyl chloride and ethylene-vinyl acetate copolymer (EVAPVC) and ternary blends of PPVC1, NBR1, and EVAPVC were formulated to study mechanical properties. For the “pure” components, elongation at break was found to be in the order PPVC1 〈 EVAPVC 〈 NBR1. Addition of both EVAPVC and NBR1 resulted in improvement of ultimate elongation and tensile energy to break. PPVC1-NBR1 binary blends exhibited synergistic behavior for both ultimate tensile stress and elongation at break, indicating the presence of appreciable specific interactions between the polymers. About 30% replacement of PPVC1 by NBR1 or EVAPVC resulted in marginal fall in modulus and significant improvement in elongation at break. EVAPVC or blends containing EVAPVC had a tendency to creep. A simple generalized equation suggested for various mechanical properties works satisfactorily. The results obtained have practical implications and indicate that PVC-based polyblends can be investigated further for potential applications in medicine.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 34 (1987), S. 1727-1738 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Thirty-five PVC formulations were compounded initially from which selected nontoxic formulations were subjected to studies in changes of mechanical, optical, migratory, viscosity, and toxicity properties due to gamma irradiation to 2.5 M rads. Degree of discoloration was found to vary from negligible to intense discoloration after irradiation on the selected samples. The nontoxic character of all samples was retained after irradiation. One formulation (R2) showed excellent radiation resistance and minimum discoloration. Effects of various additives on PVC radiation stability is also discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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