The annealing at atmospheric pressure of polymethyl methacrylate (PMMA) densified in various pressure-temperature-time cycles has been examined in the temperature range 25°-90°C. PMMA densified in the glassy state was found to be less stable than that densified by cooling through the glass transition under pressure, in agreement with previous results on inorganic glasses. Moreover, the relative stability of densified PMMA depended on the sample residence time in the glass transition region at pressure. In the one case where an energy spectrum for annealing could be calculated, the data indicated a multiplicity of molecular processes with activation energies in the range 14-19 kcal/mole.
ASJC Scopus subject areas
- Physics and Astronomy(all)