The Effect of Peroxide Cross-Linking on the Properties of Low-Density Polyethylene

Low-density polyethylene (LDPE) was chemically cross-linked with various amounts of dicumyl peroxide (DCP). The cross-link density, determined by Flory–Rehner theory, showed an increase with increasing DCP. The gel content, densities of cross-linked LDPE, thermal stability, crystallization, melting behavior, and tensile properties were studied. The results showed a new finding about the change of weight loss after cross-linking; with increase in temperature, the weight loss showed an increase below the temperature of about 450°C and then showed a decrease at temperatures from about 450°C to 500°C after being cross-linked. The crystallinity, melting point, crystallization temperature, and elongation at break decreased with the increase in DCP. However, the maximum tensile stress increased with the increase in DCP, and the cross-linked samples showed a rubber-like behavior with no flow.