Noise generation and propagation control in disc brake systems using composite friction materials composed of thermoplastic elastomers as viscoelastic materials

Attempts have been made for the first time to produce a thermal sensitive friction material by the inclusion of thermoplastic elastomers (TPE) with combined plastic and rubbery properties as viscoelastic polymeric materials into the composition of the friction material for the purpose of increasing damping behavior. To evaluate the viscoelastic parameters such as loss factor (tan δ) and elastic modulus (E′) of the friction material on the molecular scale, dynamic mechanical thermal analysis was performed on the samples. Natural frequencies and mode shapes of the friction material and brake disc were determined by modal analysis. Styrene–butadiene–styrene (SBS), styrene–ethylene–butylene–styrene (SEBS) and nitrile rubber/polyvinyl chloride (NBR/PVC) blend systems have been used as TPE materials. However, NBR/PVC and SEBS were found to be more effective in preventing the noise generation and reducing the amplitude of the brake vibrations. All the friction materials containing TPEs exhibited more damping characteristics within a wide range of temperature compared with the damping characteristics of the reference sample. POLYM. COMPOS. 27:461–469, 2006. © 2006 Society of Plastics Engineers.