Browsing by Author "SHEELA, MS"

Now showing 1 - 2 of 2
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    EVALUATION OF DGEBA
    (JOURNAL OF APPLIED POLYMER SCIENCE, 1991) TAMARESELVY, K; SHEELA, MS; KALLIYANAKRISHNAN, V; PAL, SN
    Analytical studies using chemical, spectral, and chromatographic methods have been carried out for four commerical 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-methacryloxypropoxy)]phenyl propane (BIS-GMA), an important 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.
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    STUDIES ON THE SYNTHESIS OF A METHACRYLATE-BASED DENTAL RESTORATIVE RESIN
    (JOURNAL OF APPLIED POLYMER SCIENCE, 1991) SHEELA, MS; SELVY, KT; KRISHNAN, VK; PAL, SN
    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.