Thermal behavior of a phenolic resin for brake pad manufacturing

The high-temperature behavior of a fast curing commercial phenolic resin, used as a binder in commercial car brake pads, has been investigated. The research comes from the fact that a temperature in excess of 300 °C can be reached on the surface pad in case of severe braking conditions. At this temperature, the decomposition of the resin may not only result in detrimental effects for the braking capability of the pads, but also result in a significant increase in their wear rate. The phenolic resin alone and in association with other pad ingredients (master batch), and the friction material, obtained after curing treatments, were analyzed. The main degradation steps of the phenolic resin were identified, as concerns the relevant chemical decomposition processes. The degradation of the methylene and phenol groups turned out to be the most important in terms of mass loss. In the master batch and in the consolidated friction material, the onset temperature of these processes is influenced by the presence of the other ingredients, with particular regard to some metal components. A reduction of the resin degradation onset temperature of 51 °C was observed between the pure resin and the friction material.