DYNAMIC-MECHANICAL PROPERTIES OF ISOTACTIC PMMA

The aim of this paper is a comparison of the dynamic mechanical behavi our of amorphous and partially crystallised isotactic PMMA. Parameters are proposed that affect the different relaxations that appear in the dynamic mechanical isochronal spectra. It has been found that the tem perature of the maximum of the loss tangent, as well as the activation energy, is higher for the totally amorphous polymer. The beta-relaxat ion appears clearly in the case of the completely amorphous polymer, w ith an activation energy of 105 kJ/mol; this relaxation cannot be foun d for the semicrystalline polymer.