The dynamics of tire tread compounds and their relationship to wek skid behavior

Abstract

The relationship between glass-transition temperature T _g , plateau modulus G ⁰_N , microstructure of different polymers (high cis-1,4-BR, NR, butyl rubber and various styrene-butadiene copolymers) and the wet skid resistance (WSR) of the corresponding filled treat compounds were investigated. Additionally, the relation between WSR and rolling resistance of vulcanizates was investigated. Both T _g and G ⁰_N give only a poor correlation to the values of WSR. A good correlation is reached relating the WSR of elastomers to their total viscoelastic behavior in the glass-rubber transition zone. REalistic damping curves of the polymers in this region can be obtained within a bead-spring model of a tree-like entanglement network with a certain number of subchains. It is concluded that the high-frequency dependence of the loss curve is related to the local chain dynamics, whereas the cooperative large scale Rouse-like motion of many entangled strands dominates in the low-frequency region of the loss curve. In the surrounding of the loss maximum act both intra- and intermolecular correlations.