Physical and Mechanical Behavior of Polymer Glasses. IV. Cross-Linked Poly(Methyl Methacrylate)

Temperature-induced relaxation of plastic deformation in cross-linked PMMA samples was studied. For cross-linked PMMA with a low concentration of cross-linking agent (less, than 5.2 mol.%), relaxation curves involve a low-temperature component at temperatures well below the glass transition temperature and high-temperature component at temperatures close to glass transition. Increasing the concentration of cross-linked agents in the polymer samples to 11.2 mol.% is accompanied by degeneration of the high- temperature component of the relaxation, and complete relaxation of the plastic deformation proceeds via the low-temperature component. The effect of cross-linking on the temperature-induced relaxation of plastic deformation was discussed in terms of restriction of segmental mobility within certain structural regions in the polymer sample.