A novel PDA/POSS transition layer on the surface of UHMWPE fibers by co-depositing to improve the mechanical properties of composites

The surface treatment of ultra-high molecular weight polyethylene (UHMWPE) fibers is one of the key technologies for the application of UHMWPE fibers composites. In this paper, the interface transition layer of polydopamine (PDA) and polyhedral oligomeric silsesquioxane (POSS) co-deposited on the surface of corona pre-treatment fiber fabric is used to the uniform and efficient distribution of loads between the fibers and the resin matrix, especially to significantly improve the flexural modulus of UHMWPE fiber fabric composites. Under 2.5 kW corona pre-treatment, 4 g/L of dopamine hydrochloride and 2 wt% of γ-Aminopropyl triethoxysilane aqueous solution, the impact strength, flexural strength, and modulus of UH-C2.5@PDA/PA2 fiber fabric/epoxy composites are greatly improved to 218.6 kJ/m², 151.7 MPa, and 7.8 GPa, respectively, which are 72 %, 106 % and 143 % higher than those of the untreated UHMWPE fiber composites. It may be attributed to: (1) the corona pre-treatment of UHMWPE fiber induces larger amount of active sites on fiber surface and higher surface energy, leading to a better wettability and adhesion with the matrix resin; (2) the mechanical interlocking engagement between the fibers and nano-POSS particles effectively prevents fibers extraction from the matrix resin and increases the friction of relative sliding; (3) POSS can strengthen the transition layer. The failure of UHMWPE fiber reinforced composites can be mainly attributed to energy absorption of matrix resin fracture, interface damage and relative sliding between matrix resin and fibers, fiber yield deformation and fiber fracture.