Effects of chemical surface pretreatment on tensile properties of a single glass fiber and the glass fiber reinforced epoxy composite

Abstract

The aim of this article is to determine the effect of surface pretreatments, prior to the silanization, on the structure and tensile properties of the glass fibers and their epoxy composites. Commercial glass fibers were washed with acetone to remove the soluble portion of sizing, calcinated for the removal of organic matter, activated for surface silanol regeneration, and silanizated with glycidoxypropyltrimethoxysilane (GPS). Tensile test was carried out. The morphology of pretreated glass fibers and the fracture surfaces of the epoxy composites were observed with a scanning electron microscope (SEM). The results revealed that both apparent modulus and strength of a single glass fiber and the glass fiber/epoxy resin composites strongly depend on the fiber surface pretreatments. The acetone treatment did not change appreciably the composition and tensile properties of glass fibers, but there was a weak interface between fibers and matrix. In calcinated and acid activated fibers, the two competitive effects was observed: (1) degradation of the fibers themselves and (2) improved interfacial adhesion between the glass fibers and the epoxy matrix, once the samples was silanizated. The ATR-FTIR results show that the surface content of Si-OH increases as reflected by the increasing of the Si-O band, resulting in an interaction between silane coupling agent and glass fiber.