Anchoring Ties: Improving\nEnvironmental Stress Crack\nResistance in HDPE with Styrenic Triblock Copolymer

Postconsumer recycled plastics typically exhibit low\nenvironmental\nstress cracking resistance (ESCR), which limits their use in the rigid\npackaging industry. A styrenic triblock copolymer increased the ECSR\nof virgin and recycled high-density polyethylene (HDPE) to 130%.\nScanning electron microscopy revealed well-dispersed styrene-<i>b</i>-ethylene-<i>b</i>-ethylene/propylene-<i>b</i>-styrene copolymer domains within HDPE spherulites. It\nis postulated that the rigid polystyrene domains, interconnected by\nflexible polyolefin midblocks, act as anchors that delay disentanglement\nand pullout of the tie molecules. Strain hardening modulus and in\nsitu Fourier-transform infrared-tensile tests validated this reinforcing\neffect, indicating a promising approach to improving the recyclability\nof HDPE.