Improvement of mechanical properties of composite composed of ultra-high molecular weight polyethylene fiber and epoxy resin by physical and chemical treatments

Attempts to improve the mechanical properties of the composite composed of ultra-high molecular weight polyethylene fiber and epoxy resin were made by surface (physical) treatment of the fiber and by using chemical reagent. After treating by corona discharge, the fiber was coated with silane coupling agent or reacted with isocyanate compound. The interfacial shear strength of the fiber with epoxy resin was determined by micro bond pull out method. The strength was considerably improved by using the above reagents. Especially, the surface coating with isocyanate compound was very effective and values of more than 50 MPa were obtained. The mechanical properties of the composite were also improved, as compared with those formed by corona treatment. However, the tensile strength of the composite did not reach the theoretical value, though the value of elastic modulus agreed with the theoretical value. This result may be due to the insufficient stress transmission among the fibers, because the elongation at break is more than 5%.