A facile method to prepare nanoscale polyacrylonitrile particles grafted aramid fibers for superior interfacial and mechanical properties of epoxy composites

A very simple and efficient method was developed to improve the interfacial properties of aramid fibers reinforced composites. The aramid fibers and the acrylonitrile (AN) monomers were mutually irradiated by γ‐ray in cyclohexane solution, initiating AN to polymerize on the fibers surface. Surface morphologies, chemical structure, mechanical behavior, thermal stability of the polyacrylonitrile (PAN) grafted aramid fibers and interfacial properties of their composites were systematically characterized. The results indicated that the linear PAN fantastically united to be nanoscale particles with 200 nm size, and grafted on the aramid fibers surface uniformly and compactly. Despite a slight decrease with 4°C in fiber heat resistance, the mass loss of the PAN‐grafted fibers significantly reduced. Surprisingly, the interfacial shear strength of PAN grafted aramid fibers improved by 71.50% from 36.33 ± 1.08 to 62.31 ± 1.32 MPa. Moreover, the tensile strength of aramid fibers enhanced slightly. This surface modification strategy is facile to prepare, highly efficient to enhance interface, adaptable to other organic fibers, and meaningful in multifunctional applications. POLYM. COMPOS., 39:E2436–E2444, 2018.