Abstract
The content of silane coupling agent γ-methacryloxy propyl trimethoxy silane (MPS), used in the surface treatment of glass fibers was varied within 0.1∼0.8 wt.%. To understand the role of interfacial adhesion of glass fiber/unsaturated polyester composites, contact angles of the silance-treated glass fiber were measured by the wicking method based on Washburn equation using deionized water and diiodomethane as testing liquid. In this work, Owens-Wendt and Wu's models were employed to analyze the surface free energy of composites. According to the contact angle measurements, it was observed that silane-treated glass fibers do lead to an increase in surface free energy, aminly due to the increase in its specific (or polar) component. Both the interlaminar shear strength (ILSS) of the composites determined by short-beam tests and the critical stress intensity factor ($K_{IC}$) were improved in the case of silane-treated composites compared with the control sample. and, both ILSS and $K_{IC}$ of composites exhibited a maximum value in the presence of 0.4 wt.% of silane coupling agent. It revealed that the increase of specific component of the surface free energy, of the glass fibers plays an important role in improving the degree of adhesion at interfaces in a composite system.
