Role of glass fiber surface treatment on hydrothermal aging at the interface between polybutylene terephthalate and glass fiber

The objective of this study is to characterize the role of glass fiber (GF) surface treatment in hydrothermal aging at polybutylene terephthalate (PBT) and GF interfaces from X-ray photoelectron spectroscopy analysis of the fracture surface. The mechanical properties of PBT/GF were investigated using four types of GFs treated with aminosilane and epoxy. The surface treatment containing epoxy contributed to the suppression of GF fracture during molding process and improved the interfacial strength with PBT, resulting in higher tensile strength of the PBT/GF before hydrothermal treatment. After hydrothermal treatment, the tensile strength of the epoxy-treated GF and PBT composites reduced owing to moisture absorption, and that of the aminosilane-treated GF and PBT composites decreased by hydrolysis at the interphase. Nevertheless, in the PBT/GF treated with epoxy and aminosilane together, the interfacial hydrolysis and moisture absorption during the hydrothermal treatment were suppressed, resulting in the highest tensile strength of PBT/GF.