Ultrahigh molecular weight polyethylene (UHMWPE) fibers exhibit excellent mechanical property, but their low surface activity limits the application in many fields. In this work, an efficient method was used to improve the surface activity and adhesion property of UHMWPE fibers. The amine functionalized UHMWPE fibers were prepared by the combination of bio-inspired polydopamine (PDA) and grafted hexamethylene diamine (HMDA). The chemical structure of UHMWPE fibers was characterized by X-ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy. The surface morphologies and mechanical property of the fibers were investigated by scanning electron microscopy and tensile testing respectively. In addition, a single-fiber pull-out test was carried out to investigate the adhesion property of the fibers with epoxy resin matrix. The results showed that PDA was coated on the surface of UHMWPE fibers and then HMDA was successfully grafted on the PDA layers. The excellent mechanical property of UHMWPE fibers had no obvious change. Compared with the pristine UHMWPE fibers, the interfacial shear strength of the PDA coated UHMWPE fibers with the epoxy resin matrix improved by 28.3%, while the IFSS of the HMDA grafted UHMWPE fibers had an increase of 82.7%.
AbstractPoly(vinylidene fluoride) (PVDF)/chitin (CH) blend membranes were prepared via the method of immersion-precipitation phase transformation with the solvent system N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl) as solvent and water as coagulant. The effect of CH on membrane structure and performance was investigated. Owing to the strong hydrophilicity, CH chains enriched on the blend membrane surface and improved the hydrophilicity of the membrane. The addition of CH also led to the formation of finger-like pores and the increase of pore size and porosity. The flux and the flux recovery ratio (FRR) of the blend membrane were higher than that of pure PVDF membrane. The fouling resistance of the blend membrane was lower than that of PVDF original membrane. In a word, the addition of CH to PVDF membrane improved the hydrophilicity and the anti-fouling ability of PVDF membrane.
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