Evolution of the cavity structure of HDPE/UHMWPE blends during cold stretching

Abstract The cavitation process of high‐performance HDPE/UHMWPE blends with a uniform dispersion of UHMWPE during cold stretching was investigated. It was observed that incorporating a small amount of UHMWPE into the HDPE matrix resin can serve as a nucleating agent, increasing the number of contact sites and accelerating the crystallization rate. This leads to the formation of thicker lamellar crystals and tethered molecules, ultimately enhancing the mechanical properties of the HDPE matrix. Furthermore, the relationship between the natural tensile ratio and strain‐hardening modulus was confirmed. Microstructural changes within the blends were also explored. As the drawing tangles in the middle, the cavities subsequently evolve by collapsing and merging to align parallel to the tensile direction, culminating in tensile damage forming a large crack in the final macroscopic form. As a result, the presence of more tethered molecules in the later stages of stretching inhibits further cavity growth. Highlights The HDPE/UHMWPE blends were prepared by solution blending and ultrasound‐assisted twin‐screw extrusion. The mechanisms underlying the formation and evolution of cavities in HDPE/UHMWPE blends, which lead to stress whitening during tensile damage, were examined by using DSC and SAXS/WAXD. The relationship between microstructure and mechanical properties was analyzed by cold‐drawing the molded blended sheets at room temperature.