Kinematical studies of glass transition and crystallization in glassy Se80−xTe20Inx are made using DSC technique. From the heating rate dependence of the glass transition and crystallization temperatures the activation energy, ΔEt, for the relaxation time controlling the structural enthalpy as well as the activation energy of crystallization, ΔEc, are calculated which are found to be minimum for x = 15. This is explained in terms of the structure of Se–Te–In glasses.

ABSTRACT:The synthesis of vinyl ester resins V 1 , V 2 , and V 3 was carried out using bisphenol-A based epoxy resin and methacrylic acid in the presence of triethyl-, tripropyl-, and tributyl-amines, respectively. The reaction follows first-order kinetics. The interaction between acid and amine was investigated by IR spectroscopy which shows absorptions corresponding to the formation of activated acid-catalyst complex. The specific rate constants, calculated by regression analysis, were found to obey an Arrhenius expression. The kinetic and thermodynamic parameters: activation energy, frequency factor, entropy, enthalpy, and free energy revealed that the reaction was spontaneous and irreversible with a highly ordered activated complex. The activation energy of the esterification of epoxy resin in the presence of tertiary amines increases in order V 1 < V 2 < V 3 . The experimental results were explained by proposing a reaction mechanism and deriving the rate equation. C

No abstract

The emulsion polymerization of the monomers methyl methacrylate (MMA) and 2-ethylhexyl acrylate (EHA) was studied to investigate the effect of the crosslinkable monomer poly(propylene glycol diacrylate) (PPGDA). IR spectroscopy, NMR, differential scanning calorimetry, gel permeation chromatography, and scanning electron microscopy were used to characterize the synthesized polymers. These polymers were coated on glass panels and cured at appropriate temperatures to study the physical properties, swelling behavior, surface tension, and contact angle of these polymer latices. The results show that as the concentration of EHA monomer increased, the surface tension of the latices decreased. The copolymers were characterized by 1 H-NMR spectroscopy to ensure the absence of unreacted monomer, and the results confirm the incorporation of EHA units in the copolymer. The contact angle of the latices on the glass substrate was smaller than that on the metal. The swelling mechanism of the film showed that the Fickian diffusion coefficient with 10 wt % PPGDA was at a minimum value and was the most highly crosslinked polymer among the samples. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: [676][677][678][679][680][681][682][683][684] 2011

The curing behavior of bis(methacry1oxy) derivatives of diglycidyl ether of bisphenol A (vinyl ester resin) containing acrylates (methyl, ethyl and butyl acrylate) as the reactive diluents (40% w/w) were studied by DSC analysis. Data found in this study indicated that an appreciable curing rate is obtained a t lower temperature with increased concentrations of initiator.. The acid value, activation energy, Arrhenius factor and specific heat are discussed.