Surface Modification of Basalt Fibers with Improved Reactivity, Thermal Stability, and Tensile Strength

Due to the poor interfacial adhesion of commercial basalt fibers (BFs), failure mechanisms such as fiber debonding, sliding, pull-out, and crack bridging occurred at BFs/polymer interfaces. In this work, BFs were surface modified by 3-aminopropyltrimethoxysilane (APTES) and succinic anhydride (SA) to improve their interface compatibility. The surface treatment was conducted after removing the original commercial sizing and pretreating them with high-temperatures and activation process. APTES and SA were successfully grafted on BFs rather than physical coating, it introduced specific functional groups, increased thermal stability and reduced surface defects of BFs. High-temperature reduced the –OH groups and weakened monofilament tensile strength, but activation process realized surface Si–OH regeneration, which enhanced thermal stability and tensile strength of BFs. The monofilament tensile strength of BFs followed a two-parameter Weibull distribution. The monofilament tensile strength of APTES- and SA-modified BFs increased by up to 84.3% compared with high-temperature reduced BFs. By modification, the functional groups were successfully introduced into commercial BFs, the maximum thermal decomposition temperature was 507 °C, increased by 35.7%. The modified BFs is expected to improve the overall performance of BFs/polymer composites.