Abstract:
The objective of this research is to develop polybenzoxazine composites reinforced with aramid pulp and carbon fiber as non-asbestos friction materials. Since the negative effects of asbestos, seriously about its harmful health hazard. Therefore, reinforcing fiber, i.e. aramid and carbon fiber are proposed and investigated in this work in order to replace asbestos in brake pad formulation. The effects of aramid pulp and carbon fiber mass ratio at 100:0, 75:25, 50:50, 25:75, and 0:100 on thermal, mechanical and tribological properties of the polybenzoxazine composites are systematically investigated. It is found that the mass ratio of aramid pulp:carbon fiber (75:25) in the composite renders a friction coefficient value in the ranges of 0.34−0.44 The specific wear rate of the polybenzoxazine composites in the range of 0.13x10-7 − 1.12x10-7 cm3/Nm for the temperature range of 100350ºC as required by Thailand Industrial Standard (TIS: 97-2014). Moreover, outstandingly high thermal stability and mechanical properties are observed from the polybenzoxazine filled with 75:25 aramid pulp:carbon fiber composite compared to those of asbestos commercial brake pads. A degradation temperature at 5% weight loss (Td5) of the composite is investigated to be as high as 420°C. The glass transition temperature is 219ºC where the flexural strength of the composite is 68.5 MPa. The results indicate that such developed polybenzoxazine filled with 75:25 aramid pulp:carbon fiber composite is a potential candidate for non-asbestos friction materials as brake pad.