Efficient Fabrication of High-Strength All-Polyethylene via Volume Elongation Flow Field Synergistic Hot Stretching

Ultra-high molecular weight polyethylene (UHMWPE) has garnered extensive attention for its potential to achieve supreme mechanical properties. However, conventional processing methods struggle to achieve processability and mechanical properties simultaneously due to its massive molecular chain entanglements. Herein, a dual-stage synergistic stretching strategy that combines volume elongation flow field extrusion and hot stretching is proposed to prepare high-performance all-PE composites under solvent-free conditions. High-density polyethylene (HDPE) and volume elongational flow field are employed to achieve efficient plasticization of UHMWPE, constructing a pre-structured material with chain disentanglement and good interfacial compatibility, thereby enabling a hot stretch ratio exceeding 30. During the hot-stretching process, the crystal structure of UHMWPE/HDPE blend exhibits a continuous evolution from an initial pre-ordered state to a complete shish-kebab structure, with an increase in the proportion of shish crystals, forming a high-load-bearing network centered on straight chains. As expected, the prepared all-PE composite exhibits the tensile strength and modulus of up to 416.51 MPa and 5.19 GPa, respectively. This proposed method offers a new path for the green fabrication of high-performance polyolefin composites.