SYNOPSISA homologous series of epoxy resins, based on the digylcidyl ether of bisphenol-A, were reacted with stoichiometric quantities of rn-phenylenediamine ( rnPDA) to form networks with varying crosslink densities. Infrared spectroscopic analyses revealed that the networks were formed predominantly by the epoxy-amine addition reactions with little or no OHetherification. The ultimate glass transition temperatures were inversely proportional to the epoxy chain mol wt, as predicted by a model based on the assumptions of additivity and redistributivity of free volume. The average mol wt between crosslinks, Mc, determined from the dynamic mechanical shear moduli, agreed to within 15 to 18% with the values predicted by the reaction stoichiometry. The glassy-state modulus did not exhibit any M c dependence above room temperature, however, the modulus-temperature plot for all the networks exhibited a discontinuity near -50°C with a steeper slope below -50°C than above it. The change in slope occurred over the same temperature interval as the &transition temperature of the networks. The discontinuity in the modulus-temperature plot can be attributed to the freezing of the localized motions of the molecular groups responsible for the /3-transition.

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Solubility coefficients, S, and diffusion coefficients, D, have been determined for ethane and n‐butane in poly(n‐butyl methacrylate) (PnBMA) by the microbalance technique in the temperature range from −14 to 50°C, which encompasses the glass transition of the polymer (22–35°C). S and D for ethane were found to be independent of penetrant pressure and concentration at all temperatures studied No transition to “dual‐mode” sorption behavior, as reported for a number of penetrants in glassy polymers, was observed with ethane, even at the lowest experimental temperature. Plots of log S and log D versus 1‐T, the reciprocal absolute temperature, were linear for the ethane‐PnBMA system and did not exhibit discontinuities in the glass transition region. The above results suggest that the same mechanism of solution and transport of ethane in PnBMA is operative both above and below the glass transition of the polymer under the experimental conditions. This behavior is attributed to the low “excess” free volume of glassy PnBMA, as indicated by the small difference between the coefficients of thermal expansion of this polymer in its rubbery and glassy states. Possible conditions for the appearance of dual‐mode gas sorption are discussed. A similar study with the n‐butane‐PnBMA system showed that the polymer was plasticized by the penetrant below 20°C, due to the higher solubility of n‐butane compared with that of ethane in PnBMA.

A novel approach for determining vapor−liquid equilibrium (VLE) for polymer−diluent systems is described. The concentration- and temperature-dependence of diluent−polymer Flory−Huggins interaction parameter χij is first estimated from depression in polymer melting point as a function of monomer (diluent) concentration. VLE for the polymer−diluent binary system is then obtained using an activity coefficient model and equation of state model with Aspen Polymer Plus. The technique is validated for the syndiotactic polystyrene−toluene and syndiotactic polystyrene−methyl ethyl ketone and is extended to polybutylene terephthalate − with various diluents such as butanediol, tetrahydrofuran, isophorone, 1-methylnaphthalene, and benzonitrile, systems hitherto not reported in the literature.