Interfacial effect of silane coupling agent in GFRP with a new evaluation technique.

In this study, interfacial mechanical properties of glass/epoxy composites were evaluated for some kinds of silane treatments on glass fiber with the aid of an embedded single filament tensile test that is generally employed for measurement of interfacial shear strength. However, this technique has some problems such as difficulty of specimen manufacturing and determination of critical state. A new evaluation method of the interface is proposed in this paper to overcome these problems. In this method, the fiber fracture was monitored by a video camera and image processor during the tensile test for the embedded single-filament coupon. The first fracture of the embedded filament in the fiber fracture process was used to evaluate interfacial properties. The applied stress of the embedded filament at the first fracture, σf1b, is calculated on the basis of the elastic model and compared with the strength of filaments sf. The fact that sf is smaller than σf1b means the inefficiency of the tensile load transfer due to the interfacial mechanical properties. The ratio of sf to σf1b is named 'interfacial transmissibility'. The effect of the chemical structure of a silane coupling agent on interfacial transmissibility was investigated.