Robust asbestos-free brake pad from eucalyptus fiber reinforced polybenzoxazine composites

Abstract

Abstract This study explored the development of a robust asbestos-free brake pad composite material from benzoxazine resin, eucalyptus fibers and other constituents. Two different samples involving bleached and unbleached eucalyptus fibers reinforced polybenzoxazine composites were produced, denoted by BEFPC and UEFPC respectively. The effects of bleached and unbleached eucalyptus fibers reinforcement on the mechanical, thermal and tribological properties of the composite were investigated for the first time. The results obtained suggested that both the two composites possesses good flexural properties, great thermal stability, and high coefficient of friction (COF) at 5 wt% fiber reinforcement. The degradation temperature at 5% weight loss (Td5) for PBEC and PUBEC stood at 368 and 342 ℃ respectively, with both having residual weight of more than 68%. Storage modulus of 5.25 and 5.10 GPa, and glass transition temperature (Tg) of 219 and 237°C were recorded for the BEFPC and UEFPC respectively. Findings from the study of flexural strength of the BEFPC and UEFPC conducted reveals that the flexural strengths were as high as 54.5 and 51.3 MPa respectively. Furthermore, interesting results from the study on the tribology of the composites shows that the coefficient of friction (COF) is in the range of 0.2–0.7, and wear rates were lower than 3.5×10− 7 cm3/Nm as required by Thailand Industrial Standard (TIS: 97-2014). Therefore, this study presents eucalyptus fiber-reinforced polybenzoxazine brake pad composites (EFPBC) as a potential friction materials for the automobile industry.