Characterization of benzoxazine resins for brake pad friction materials manufacturing

Phenolic resins are the most commonly used binders in brake pads for automotive disc brake systems owing to their affordability and thermal properties. However, they also show some limitations related to their crosslinking mechanism. Benzoxazine resins present themselves as possible alternatives for this application by providing enhanced thermal properties as well as other industrially attractive characteristics such as lower moisture absorption and unlimited shelf life. This study investigates the thermal properties of two different benzoxazine resins, with the aim of assessing their capabilities as binder for brake pad and of understanding how to process them in order to actually employ them as such. DSC, TGA, hardness and tribological analyses were carried out on neat resin samples and on friction materials containing them as binder. The presence of several concurring reactions was detected during the crosslinking reaction of benzoxazine resins. The benzoxazine resins showed lower mass loss respect to a phenolic resin in the temperature range of interest for commercial brake pads application. Friction material containing benzoxazine resin binder showed promising tribological results.