AGING CHARACTERISTICS OF TERNARY BLENDS OF POLYETHYLENES. I

Abstract

Degradation of a low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE)/high-density polyethylene (HDPE) blend having different weight ratios of LLDPE (10–35 wt%) and HDPE (40–65 wt%) with fixed percentage of LDPE (25 wt%) was studied by aging the film samples at 55, 70, 85, and 100°C in air. Reactions involved in changing the molecular structure and formation of oxygenated and unsaturated groups during thermo-oxidative degradation are discussed. The molecular weight (M _v) showed very little change in the initial hours of aging at different temperatures. Tensile strength was found to increase initially and then decrease with aging time. The increase in tensile strength suggests molecular enlargement, mainly by recombination of alkyl and alkoxy radicals, which produces nonradical products. The thermal stability decreases with increase in aging time and temperature.

Keywords:

• Blend
• Crystallinity
• Elongation at break
• Gel content
• High-density polyethylene
• Infrared spectra
• Linear low-density polyethylene
• Low-density polyethylene
• Molecular structure
• Oxygenated and unsaturated groups
• Tensile strength
• Thermal aging
• Thermal degradation
• Thermal stability
• Viscosity average molecular weight

Acknowledgments