A Novel Strategy to Enhance the Mechanical Properties of <scp>UHMWPE</scp> Fiber Composites

ABSTRACT To improve the surface activity of UHMWPE fiber, this study developed a novel interface transition layer. First, a designed and synthesized amphiphilic radical initiator, which can cover the surface of UHMWPE fibers by molecular self‐assembly, achieved the free radical precipitation polymerization of diacetone acrylamide (DAAM) and trifunctional crosslinking agent (TMPTA) onto the UHMWPE fiber surface, and formed chemical bonding through the transfer of free radicals to UHMWPE chains to improve the interfacial bonding strength between the DAAM polymer layered and UHMWPE fibers. Subsequently, the DAAM polymer layer reacts with adipic acid dihydrazide (ADH), condensing to form a three‐dimensional network structure. The research results indicate that some DAAM polymers had been successfully grafted onto the fiber surface via the free radical chain transfer mechanism. For the optimally treated UH‐DAAM/TMPTA@ADH fiber, single fiber pull‐out tests revealed a significant 205.8% increase in interfacial shear strength, compared to the untreated fiber, and the corresponding composites achieved a 76.9% improvement in impact strength (225.2 kJ/m 2 ), while flexural strength and flexural modulus increased by 57.9% (116.2 MPa) and 193.8% (9.4 GPa), respectively. Failure analysis indicated that effective stress redistribution and multiscale energy dissipation were realized through matrix tearing, interphase‐matrix interfacial damage, relative sliding at the matrix/interphase/fiber tri‐junction, and fiber yield deformation. This work established a rapid and scalable modification process, substantially mitigating the drawbacks of existing methods (such as polydopamine modification) in terms of dyeability, time‐consuming, and cost.