Polybenzoxazine-Based Self-Lubricating and Friction Materials

Abstract

A benzoxazine binder modified by incorporating (1) friction additives, such as graphite, alumina, silicon oxide, zirconium silicate, and coke; (2) reinforcing fibers, such as aramid pulp, potassium titanate, ceramic fiber, and steel wool; and (3) fillers, such as amine-terminated butadiene-acrylonitrile copolymer liquid rubber, styrene-butadiene rubber, nitrile butadiene rubber, calcium carbonate, barium sulfate, or cashew dust is manufactured for self-lubricating and friction composite materials. Friction coefficient, specific wear rate, storage modulus, as well as glass transition temperature are the major properties being evaluated in this work. With appropriate formulation, the polybenzoxazine composites were observed to show very outstanding tribological properties that can be tailored to various needs as the composites exhibit stable friction coefficient in a range of 0.15–0.65 with substantially low specific wear rates of 0.20 × 10⁻⁴–0.89 × 10⁻⁴ mm³/Nm. Furthermore, a stable friction coefficient with an average value of 0.43 for polybenzoxazine frictional composites over a wide range of braking temperature from 100°C to 350°C can be obtained. The storage modulus at the room temperature of the polybenzoxazine composites with the value as high as 20 GPa and with a significantly high glass-transition temperature in a range of 190–300°C is reported. As a consequence, the obtained polybenzoxazine-based composites exhibit high potential to be used as bearing materials or brake pads where optimal friction coefficient, high wear resistance, and modulus with good thermal properties are required.