Effect of Molecular Structure Parameters on Crystallinity and Environmental Stress Cracking Resistance of High‐Density Polyethylene/TiO2 Nanocomposites

Abstract The correlation between molecular microstructure with crystallization behavior and environmental stress cracking resistance (ESCR) for three commercial grades of high‐density polyethylene and their nanocomposites has been investigated. Molecular architecture was characterized using high‐temperature gel permeation chromatography (GPC) test. Qualitative comparison of crystallinity and side chain branches of neat high‐density polyethylenes (HDPEs) has been performed using FTIR test and results were in good accordance with GPC results. Investigation of crystallinity and effect of side chain branches on the crystallite's dimensions has been carried out by DSC and XRD tests. Moreover, it was found that addition of nano‐TiO2 to HDPE causes an increase in crystal content and a decrease in crystal size, simultaneously. It was concluded from ESCR characterization that molecular weight and side chain branches are the most important structural parameters affecting ESCR properties of HDPE. The significance of side chain branches is higher compared to molecular weight.