Abstract
The effect of size of natural graphite (NG) particles on the tribological and mechanical properties as well as thermal stability of polybenzoxazine composites with five different sized NG particles (32, 38, 45, 53, and 75 µm) was studied. The tribological performance of the composites performed in pin-on-disk tester was improved with adding larger NG particle size. It was found that the wear resistance of the composites was improved by increasing of the particle size. While, the increased NG particle size reduced the friction coefficient of the composites from 0.36 to 0.31. In term of mechanical properties under flexural test, i.e. flexural modulus and flexural strength, the NG particles with the largest size possessed the suitable reinforcement ability. Glass transition temperature evaluated by dynamic mechanical analysis and the degradation temperature at 5 % weight loss measured by thermogravimetric analysis of the composites was in a temperature range of 195 oC – 215 oC and 387 oC – 402 oC, respectively. Therefore, the obtained outstanding properties, i.e. friction coefficient, flexural modulus and strength, glass transition temperature, and degradation temperature make the polybenzoxazine composites highly attractive to be utilized as friction materials.
