Strikingly Enhancing Environmental Stress Crack Resistance of HDPE via a Small Fraction of a PE-Based Covalent Adaptable Network

Environmental stress cracking (ESC) is a critical and widespread failure mechanism in polymer materials, posing significant challenges for long-term durability and performance. In this work, we report an effective approach to enhance the environmental stress crack resistance (ESCR) of high-density polyethylene (HDPE) by incorporating a polyethylene-based covalent adaptable network (PE-CAN), Sur-ESO_x, synthesized via the crosslinking of Surlyn resin (ethylene-methacrylic acid copolymers with zinc ions) with epoxidized soybean oil (ESO). Two preparation methods were explored, with the one-pot method showing superior interfacial adhesion and strengthened entanglements between HDPE and Sur-ESO_x. The resulting blends demonstrated significantly improved ESCR, with F₅₀ values exceeding 290 h at 10 phr Sur-ESO₄, compared to only 3 hours for neat HDPE. Importantly, the dynamic network structure of Sur-ESO₄ preserved processing and mechanical properties with minimal losses. These findings provide valuable insights into enhancing polymer durability and broadening the applications of CANs.