STRUCTURAL RELAXATION OF GLASS-FORMING POLYMERS BASED ON AN EQUATION FOR CONFIGURATIONAL ENTROPY .2. STRUCTURAL RELAXATION IN POLYMETHACRYLATES

The dependence of the heat capacity on temperature measured in DSC hea ting scans after different thermal histories in poly(methyl methacryla te), poly(ethyl methacrylate), and poly(butyl methacrylate) is reporte d. These results are analyzed with the help of a phenomenological mode l for the evolution of cofigurational entropy under arbitrary historie s. The possibility of obtaining material parameters from the experimen tal results is discussed. The dependence of the relaxation times in eq uilibrium conditions on temperature is calculated for the three polyme rs and compared with the results of the main viscoelastic and dielectr ic relaxation processes reported in the literature. The width paramete r of the Kohlrausch-Williams-Watts relaxation function is also calcula ted for the three polymers of this series.