Quantitative analysis of the temperature effect on the radiation crosslinking and scission of polyethylene macromolecules

The gamma -radiation-induced crosslinking of low-density polyethylene over a wide temperature range was studied with a new log-logarithmic scale metho d for sol-gel analysis. A straight line was always obtained for the plottin g of log (sol fraction) against log (dose). Gel points were accurately obta ined from the plot intersects, and scission/crosslinking ratios were obtain ed from the plot slopes via computer simulations with GelSim6 software. The crosslinking and scission yields were determined to be 0.17 and 0.078 mmol /kJ, respectively, at 30 degreesC, and they increased to 2.3 and 4.4 mmol/k J, respectively, at 300 degreesC. The observed regularities are explained b y the fact that enhanced macromolecular motion decreases the cage effect on recombination reactions in the polymer. (C) 2001 John Wiley & Sons, Inc.