Influences of the average molecular weight of phenolic resin and potassium titanate morphology on particulate emissions from brake linings

The effects of the binder resin and potassium titanate components of brake linings on the amounts of particulate matter (PM) emitted during brake applications were investigated. The studied lining specimens contained phenolic resins with different molecular weights and potassium titanate whiskers and granules. Brake emission tests were performed using a Krauss-type brake tester enclosed within a ventilated chamber, and the PM concentration was measured by an optical particle counter. The obtained results showed that the airborne PM produced during brake applications had a unimodal particle size distribution with a peak centered at approximately 2.5 μm regardless of the lining composition. However, the wear particles settled inside the chamber were composed of agglomerated ultrafine particles, suggesting their further possible resuspension as airborne ones. The linings fabricated from the high-molecular-weight resin and granular potassium titanate exhibited low brake emissions, and the PM reduction observed for granular potassium titanate was greater at higher temperatures due to the facilitation of contact plateau formation on the lining surface. •Shape of potassium titanate affected more on emission than molecular weight of resin.•Contact plateaus on the lining surface showed a strong influence on brake emission.•Both airborne and settled particles were mainly composed of ultrafine ones.•Settled fine wear particles could resuspend at any time after brake applications.