The enthalpic ageing behaviour of poly(methyl methacrylate) was studied by differential scanning calorimetry for several ageing temperatures, and ageing times up to 104 min. The data are interpreted in terms of both the phenomenological multiparameter model and the Cowie-Ferguson model. The phenomenological multiparameter model was found not to provide an adequate description of the enthalpic ageing process(es) occurring in poly(methyl methacrylate). Problems encountered in defining the equilibrium glassy state by extrapolating from liquid enthalpy data are also discussed.
Посилання на статтю:
Physical ageing of poly(methyl methacrylate) from enthalpy relaxation measurements / J. M. G. Cowie* and R. Ferguson // Polymer. – 1993. – Vol 34. – P. 2135-2141.