Optimization of phenolic resins for friction materials

Abstract The physicomechanical properties of phenolic composites containing a large amount of mineral fillers were enhanced through a chemical modification of the basic resin. Various phenolic compounds were first introduced in the condensation mixture leading to modified novolaks, but the final properties of the resulting composites were only slightly improved. Better results were obtained using an optimum content of epoxy‐novolak or melamine in the last stage of processing as confirmed by static and dynamic mechanical analysis. The new procedure introduced recently by Halpin and Sendeckyj for fitting fatigue models was applied to our particle‐filled material. The results confirm the reinforcement of the composite through the co‐reactivity of phenolic resins with the introduced species in the final curing stage.