Photooxidative degradation of graphene-reinforced high-density polyethylene nanocomposites

Natural weathering of high-density polyethylene (HDPE) and its graphene nanocomposites was studied. The nanocomposites, prepared by in situ polymerization of ethylene, were exposed to the natural environment for 30, 60, and 90 days. The effects of weathering on the crystallinity, melting temperature, and lamellar thickness distribution were studied using differential scanning calorimetry. The changes in chain microstructure and molecular weight were determined by crystallization analysis fractionation and gel permeation chromatography, respectively. The effects of weathering on the dynamic mechanical properties and the morphology of the nanocomposite were also determined. The parent HDPE suffered severe degradation as expected. However, graphene-reinforced HDPE nanocomposites show resistance to degradation. The changes in the crystallinity, lamellar thickness, molecular weight, and dynamic mechanical properties of graphene nanocomposites were less pronounced as compared to the parent HDPE. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47030.