Effects of Chemical Bonding and Temperature on Interfacial Strength of Glass/Polyamide Resin

Abstract

The mechanical properties of fiber-reinforced thermoplastics (FRTP) are greatly affected by the interfacial shear strength, so it is important to evaluate the interfacial properties. The single fiber pull-out test and micro-droplet test are typical methods to evaluate interfacial shear strength. However, these test methods are difficult to evaluate only the effect of the chemical bonding on the interfacial strength because the interface is not only affected by chemical bonding but also by residual stress, which is easily influenced by external factors. In this study, we conducted stud-pull test and tensile shear test using a glass plate coated with aminosilane and a rod-shaped polyamide 66 resin to evaluate the chemical bonding at the interface while the effect of the resin's tightening force on the fibers was small. The stud-pull test and the single fiber pull-out test were also conducted under high temperature condition, to clarify the effect of test temperature on the chemical bonding. In the stud-pull test at 25 °C, the aminosilane treated glass plates had a 7.7 times higher interfacial strength compared to the untreated glass plates. In the single fiber pull-out test, which is greatly influenced by the force with which the resin tightens the fiber, the fiber matrix interfacial shear strength of aminosilane-treated glass fiber and PA66 at 80 °C tended to be lower than that at 25 °C; whereas there was no difference in interfacial strength of aminosilane treated glass plate and Polyamide 66 obtained by the stud-pull test. These results indicated that the chemical bonding which affects the interfacial strength can be evaluated by stud-pull test, and the chemical bonding at the interface between aminosilane treated glass plate and polyamide 66 was less affected by the 80 °C condition.