Friction and wear properties of polybenzoxazine/acrylonitrile-butadiene rubber composites for brake pads application

Abstract

This research aims to develop acrylonitrile-butadiene rubber particles (NBR)-filled polybenzoxazine (PBA-a) composites as friction materials for brake pads application. The effect of types of NBR, i.e. ultrafine-NBR (UNBR) and micro-NBR (MNBR) on friction and wear, and thermomechanical properties of the PBA-a/NBR composites was investigated. From the results, the coefficient of friction of all PBA-a/UNBR and PBA-a/MNBR composites clearly increased with increasing rubber particle contents, i.e. 0.50-0.62 for the PBA-a/UNBR and 0.50-0.61 for the PBA-a/MNBR. In addiion, the lowest specific wear rate belonged the PBA-a filled with 5wt% of UNBR because the deformation of rubber particle plays a protective role against the wear damage of the composite. Whereas, the agglomeration of rubber particles was observed for the PBA-a filed with rubber particle over than 10wt%, resuting in an decrese in the specific wear rate due to easy detachment of NBR particles from the PBA-a matrix. Futhermore, the PBA-a/5wt% UNBR can maintain friction performance at temperature range of 25, 100, 150, 200 and 250oC. For the thermomechanical properties, the storage modulus at room temperature decreased with an increasing of rubber particle contents, while the PBA-a/UNBR and PBA-a/MNBR composites showed sinificantly high glass transition temperature found from the peak of loss modulus from dynamic mechanical analysis approximately 170-188oC.