THE ACTIVATION-ENERGY OF OXIDATIVE THERMAL-DEGRADATION OF RADIATION-CROSS-LINKED AND PEROXIDE-CROSS-LINKED LOW-DENSITY POLYETHYLENE

The parameters of thermal degradation (kinetic order of the reaction, preexponential factor logA, and activation energy E(d)) of low-density polyethylene crosslinked by radiation or by dicumyl peroxide were det ermined from thermogravimetric data processed using the complementarit y-based method of ''supercorrelations''. The degradation of the polyme r was found to obey a first-order rate equation. At mass losses of 10 - 20%, the parameters logA and Ed were shown to decrease with an incre asing degree of crosslinking because of the evolution of low-molecular radiolysis products and the low probability of chain radical processe s. In the region of more intense destruction, E(d) (as well as logA) i ncreases because the degradation of crosslinked polymer macromolecules requires greater energy consumption.