KINETICS OF RADICAL DECAY AND MOLECULAR-DYNAMICS IN ORIENTED HIGH-MODULUS POLYETHYLENE

The kinetics of decay of macroradicals in irradiated ultradrawn (draw ratio 200) high modulus polyethylene, single crystal mats of polyethyl ene and polyethylene with extended chain crystals was studied comparat ively by the ESR technique. The results were analyzed from the viewpoi nt of correlations between the microstructure and temperature-dependen t chain dynamics of the polymers. The actual absence of appreciable ra dical decay in the temperature range 200-300 K and a remarkable stabil ity of considerable fraction of initial radicals at higher temperature s in high modulus sample were explained by extremely restricted motion of the fragments of unfolded tie molecules in trans-conformations pre dominating in the amorphous region of this polymer. In addition, direc t evidences for drastic conformational changes in amorphous regions of polyethylene as a result of ultradrawing obtained by IR-spectroscopy are reported.