Free volume theory and nonlinear thermoviscoelasticity

摘要: The rheological behavior of polymers in the neighborhood glass transition is investigated framework free volume theory nonlinear viscoelastic behavior. Free as normally applied above modified to account for effect residual vacancies below transition; this modification accomplished by modeling changes state polymer sum and a random disturbance deriving from thermal collisions between molecule segments. mechanical properties passing across follow freezing-in relaxation mechanisms volume; model, which also incorporates time-dependent coefficient expansion under isobaric conditions, does not require additional parameters other than those characterizing rubbery state. pressure dependence found be qualitiative agreement with measurements on PVAc, while ratio glassy heat capacities coincide equilibrium bulk compliances domains.