Enhancing performance of silica-reinforced natural rubber tire tread compounds byapplying organoclayas secondary filler

Silica-reinforced natural rubber (NR) tire tread compounds are investigated using organoclay (OC) as secondary filler. Byvarying mixer temperature settings at a silica/OC ratio of 45/10 phr, dumptemperatures are reached of approximately 120, 140, 150, and 160 °C. The increased dump temperature leads to a better silanization reaction resulting in lower mixing torque, Mooney viscosity, and Payne effect. The optimum mixing dump temperature was found to be around 150 °C. By varying the loadings of OC in the silica-filled NR compounds from 0 to 36 wt% relative to total filler amount, the increased OC loadings decreased the Payne effect and compound viscosities, significantly shortened scorch and cure times, and raised the tan delta at -20 and 0 °Cas indications for ice traction and wet skid resistance of tire treads made therefrom. The optimum loading ofOC of 9 wt% relative to total filler content shows better Payne effect, cure rate index, tan delta at-20 and 60 °C indicative for rolling resistance, and DIN (German Institute of Standardization) abrasion resistance index. The results indicate that the use of this hybrid filler may provide tires with better wet traction and lower rolling resistance and wear resistance compared with the pure silica-filled system

Improvement of Silica-reinforced Natural Rubber Tire Tread Compounds by Joint Hybridization With Small Amounts of Secondary Fillers and Polymers

To improve the properties of silica-reinforced truck tire tread compounds, especially abrasion resistance, the effect of vinyl contents in butadiene rubber (BR) or solution styrene–butadiene rubber (SSBR) as secondary polymers in silica-filled natural rubber (NR) compounds at a ratio of 80/20 phr is investigated in the first part of this study. By increasing the levels of vinyl contents in BR in combination with NR, a better Payne effect, 300% modulus, reinforcement index, and tan delta at −20 and 0 ° C are obtained, whereas the tensile strength, elongation at break, and DIN abrasion resistance index decrease with increasing vinyl contents. Higher vinyl contents in SSBR result in improvements in Payne effect, 300% modulus, tan delta at −20 and 0 °C but only a small improvement in DIN abrasion resistance index. Combinations of secondary fillers and polymers in silica-filled NR are covered in the second part of present study. Silica/carbon black–filled NR/BR and NR/SSBR, respectively, and silica/organoclay–filled NR/BR and NR/SSBR show positive effects on scorch time and optimum cure time, with only slight changes in Payne effect, tensile properties, tan delta at −20 and 0 ° C and DIN abrasion resistance as compared with compounds with carbon black N134. The use of organoclay results in an enhanced Payne effect and tan delta at 60 °C, indicative of reduced filler–filler networking and consequently a lower rolling resistance of tire tread compounds as compared with the compound without organoclay. The specific combination of a small amount of organoclay replacing the same amount of silica, together with some of the NR replaced by high-vinyl BR, promises a substantial overall boost in wet and ice traction, abrasion, and wear resistance as compared with straight NR/silica tire treads. This new observation helps to overcome one of the main shortcomings of NR/silica compounds: their generally low wear resistan

Elucidating the role of clay-modifier on the properties of silica-and silica/nanoclay-reinforced natural rubber tire compounds

Organoclay (OC) is one of the potential secondary fillers to be applied in silica-reinforced rubber compounds for tire applications. Commercial OC contains a large proportion of surface modifier, i.e., dimethyl dihydrogenated tallow am-monium chloride (2HT) type, that has an influence on the compound properties. To elucidate the effect of 2HT on the properties of silica-Natural Rubber (NR) compounds, a silica-only system, silica/OC, and silica/montmorillonite (MMT)/2HT added in situ during mixing, were comparatively studied. Irrespective in which form 2HT is added, it has potential to further enhance the performance of silica-NR compounds. Incorporation of 2HT suppresses filler flocculation and improves process-ability. Overall, the silica-only filled compound shows better mechanical properties than the silica/clay dual filler systems. The use of a small amount (2.4–4.7 phr) of 2HT improves 300% modulus, tear strength and abrasion resistance. The silica/OC gives better mechanical properties than the silica/MMT/2HT. With the optimum content of 2HT, a higher tan δ at –20°C and lower tanδ at 60°C can be achieved, all showing the beneficial potential of utilization of the modifying agent to improve wet traction and rolling resistance of silica-based tire tread compounds