No abstract

For green tires, carbon black (CB) is partially replaced by silica (SiO 2 ) in the tread formula in order to improve wet grip (WG) and fuel saving efficiency (FSE). However, such replacement inversely affects electrical conductivity of a tire resulting a greater potential for static shock or electrostatic ignition. This work aimed to improve electrical conductivity of the tread compound by partially replacing either CB or SiO 2 by 0-12 phr of conductive carbon black (CCB) (with replacing ratio of 2:1) and investigating the effect of such replacement on the tire performance. Although the partial replacement of CB or SiO 2 by CCB increased the magnitude of transient filler network resulting in the negative effects on heat build-up, WG and FSE of the tread vulcanizates, it significantly improved electrical conductivity. Surface resistivity decreased sharply when CB or SiO 2 was replaced by 3 phr of CCB, revealing the point of percolation threshold. In addition, the partial replacement of CB or SiO 2 by CCB did not cause significantly change of both hardness and tensile properties.At any given CCB loading, the SiO 2 replacement provided greater surface conductivity and higher abrasion resistance with lower WG and FSE than the CB replacement.

No abstract

EU tyre labelling rules have been applied since November 1st, 2012, to inform about the performances of tyres on fuel efficiency (rolling resistance), safety (braking on wet surfaces) and noise (external noise). The tyre labels help customers to make their purchase decisions by trade off on tyre performances and prices. Consequently, manufacturers have to engineer their products so that their tyres are classified on top of the label categories. Tyre rolling resistance involves in many kinds of tyre knowledge such as rubber formulations, tyre structures and tyre tread patterns. Generally, 70% of tyre rolling resistance depends on the hysteresis properties of rubber compounds and 30% depends on other properties such as road conditions, tyre pressures, load carrying, vehicle speeds, and tyre tread designs. From this point of view, even if rubber compounds are formulated to have good hysteresis properties, they can help reduce tyre rolling resistance up to 70%. If tyre rolling resistance needs to be further reduced, tread designs have to be considered. Therefore, this case study will show how to reduce tyre rolling resistance by using Finite Element Analysis (FEA). Pneumatic light truck tyres were used to study their tread patterns, tread depths and contact areas affecting their rolling resistances, while solid tyres were used to study on their tread patterns, tread depths, contact areas and tyre structures affecting their rolling resistances. The FEA results showed that tread patterns had high effects on rolling resistance of pneumatic light truck tyres while they had little effects on solid tyres. Contact areas and tread depths affected rolling resistances of both tyres. Increase in contact areas reduced tyre rolling resistances while increase in tread depths resulted in higher tyre rolling resistances.

In this study, the effects of hybrid filler ratio and styrene‐butadiene rubber (SBR) type on tire tread performance that is, wet grip (WG), fuel‐saving efficiency (FSE), and abrasion resistance, were focused. Two types of SBR that is solution‐SBR (S‐SBR) and emulsion‐SBR (E‐SBR) were selected and reinforced by various ratios of highly dispersible silica (HDSi) to carbon black (CB). Although increasing the CB ratio had negative effects on WG, FSE, heat build‐up, and dynamic set, it improved abrasion resistance. Results revealed a good balance of tire performance at a CB ratio of 40 wt%. Clearly, S‐SBR provided better overall tire performance than E‐SBR, particularly in the silica‐filled system. This is possibly due to the higher glass transition temperature (Tg) and the greater magnitudes of rubber‐filler interaction and crosslink density of S‐SBR. Surprisingly, the HDSi/CB hybrid ratio and the SBR type had little influence on the degree of filler dispersion, probably because of the sufficiently long mixing time employed in this experiment.