The role of additional silane coupling agent treatment in oxygen plasma-treated UHMPE fiber/vinylester composites

Ultra-high modulus polyethylene (UHMPE) fiber was treated with oxygen plasm a and a silane coupling agent in order to improve the interfacial adhesion between the UHMPE fiber and vinylester resin. The oxygen plasma and gamma-m ethylmethacryloxypropyltrimethoxysilane (gamma-MPS)-treated UHMPE fiber/vin ylester composites showed a slightly higher interlaminar shear strength tha n the oxygen plasma-treated UHMPE fiber/vinylester composites. The interfac ial adhesion of the oxygen plasma-treated UHMPE fiber/vinylester composites in this study is mainly due to mechanical interlocking between the micropi ts formed by the oxygen plasma treatment and the vinylester resin. The gamm a-MPS molecules adsorbed onto the UHMPE fiber surface neither affected the morphology of the UHMPE fiber surface, nor reduced the extent of mechanical interlocking. The improved interfacial adhesion by the gamma-MPS treatment is due to enhanced wettability and chemical interaction through the chemic ally adsorbed gamma-MPS molecules, as detected by Fourier-transform infrare d (FT-IR) spectroscopy. The gamma-MPS molecules adsorbed onto the ultra-hig h molecular weight polyethylene (UHMWPE) plate surface also reduced the agi ng effect of the oxygen plasma-treated UHMWPE surface.