Influence of crosslinking on the plastic behavior of amorphous polymers at large strains

The mechanical properties of three grades of PMMA, one linear and two crosslinked, are investigated in tension below and above the glass transition temperature. It is Sound that strain-hardening decreases gradually with temperature in the glassy state, but keeps a significant value in the rubbery state. The results are analyzed in terms of an entropy-based statistical model (van der Giessen and Wu, 1992) which describes the stress-strain response of a chain network. The junctions of the network are not only associated with the chemical crosslinks, but additionally with physical entanglements, which are more numerous in the glassy state.