Reactive Processing Of Silica Reinforced Nr And Its Structure And Properties

With the implement of EU tire new labelling regulation and REACH,environmental safety and comfortable green tire has become the feature development direction. At present, silica can almost replace the carbon black in personal car tire tread formulation. It has become a important subject of silica in rubber industry that how to further promote the application of silica in tire tread formulation. In this paper,we chose the NR truck tire tread formulation, and studied the reactive processing of silica reinforced NR by the aspects of comparing the difference between CSDPF and common silica/CB filler system, optimizing the mixing technology, increasing the polarity of the rubber matrix and adjusting the curing system.With increasing of the ratio of silica to CB, the curing rate and Payne effect of NR compounds both decreased gradually. The crosslinking density and the abrasion resistance of NR vulcanizates showed a reduced trend, however the dynamic performance improved, which the rolling resistance and compression heat build-up decreased. The size of CB-silica dual phase filler(CSDPF) agglomeration was smaller and the compounds filled by CSDPF showed weaker Payne effect. The NR vulcanizates showed better performance with the cooperation of Si-69.The higher mixing temperature(150℃) was beneficial to the silanization reaction between silica with Si-69 on the premise of the same mixing time. The silica filled NR compounds presented a weaker filler network structure and slower silica flocculation rate and stronger silica-NR interaction. The hydroxyl absorbtion peak of silica filled NR compounds was smaller than others. By prolonging the time of silanization reaction, the Mooney viscosity and curing rate of NR compounds increased. But thecuring rate of NR compounds in the mixer was higher than that in the oven for the extra shear effect. In the meaning time, the filler dispersion degree L of NR compounds in the mixer was smaller and decreased with the time of silanization reaction. The heat buildup and tanδ at 60 to 80℃ of NR compounds mixed in the internal mixer with 5 minutes were smaller relatively.By improving the dosage of epoxidized natural rubber(ENR) or increasing the epoxidized degree in the same dosage, Moony viscosity of NR compouds increased but the curing rate slowed slightly, and the interaction between rubber matrix and silica enhanced. The tensile strength and elongation at break both decreased slightly, but the modulus improved obviously. The hysteresis peak at 0℃ enlarged leading to the wet traction promoted obviously t but he rolling resistance raised a little. ENR can enhance the interaction between rubber matrix and silica, in the same time could react with silica. When the ENR cooperated with Si-69, it could further weaken the polarity of silica, and the mechanical properties and abrasion resistance of vulcanizates were superior, and the rolling resistance was maller.With increasing the amount of NS and sulphur, the curing rate and crosslinking density of NR compounds increased gradually which led to the increase of300%modulus and the decrease of elongation at break. At the same time, the abrasion resistance of NR vulcanizates enhanced, which the DIN and Akron abrasion volume decreased gradually. The tanδ decreased with the increasing of crosslinking density in the frequence and temperature sweep, which was consistent with the result of dynamic heat buildup.