EFFECT OF GAMMA-IRRADIATION ON THE MELTING CHARACTERISTICS OF ULTRA-HIGH-MOLECULAR-WEIGHT POLY(ETHYLENE OXIDE)

To follow the effect of gamma irradiation upon the poly(ethylene oxide) melting characteristics, differential scanning calorimetry investigations have been carried out. The dependencies of the first and second melting points and enthalpies on the irradiation dose are discussed in terms of tie molecules and surface energy in order to make a balance of enthalpies. It is affirmed that three fractions are formed as a result of concurrently running radiation degradation and crosslinking: macronetwork consisting of slightly crosslinked long chains, micronetworks consisting of short, highly branched and crosslinked molecules and sol-fraction consisting of short linear or slightly branched molecules. The interaction between the fractions determines the thermal behaviour of the irradiated polymer.