Study On Precipated Silica Applications In NR Truck Tire Tread

Precipitated silica filled rubber has been widely used in the tire industry for its excellent wet skid resistance and low rolling resistance, low heat performance. NR truck tire tread was chosen for the base formulation in this paper. The effect of accelerators, coupling agents and dispersing agents on properties of NR filled with silica/carbon black were investigated in the paper for optimizing the componding system. At the same time, the microstructure of NR vulcanizates and dynamic performance of NR compounds were characterized by Scanning Electron Microscope (SEM) and Rubber Processing Analysis (RPA).The effect of different alkaline accelerators on the properties of silica/carbon black composites filled NR were studied. The experimental results showed that with the increase of DPG amount, the curing time of NR compound was shorten and the crosslink density increased. The tensile strength, modulus and hardness of vulcanizates slightly increased and the abrasion resistance was improved. The suitable amount of DPG was 0.4phr. With the incorporation of DTP, the mooney viscosity of NR compound decreased, curing rate increased. The tensile strength and abrasion properties of NR vulcanizates were improved. The accelerating effect of DTP was inferior to that of DPG. The adding order of DPG affected the properties of filler dispersion and the properties of NR. When DPG was mixed in open mill, the filler dispersion in rubber matrix was better. The vulcanizates had the lowest rolling resistance and best abrasion resistance when DPG was added in open mill.The effect of silane coupling agents on the properties of NR filled by silica/carbon black showed that Si747 imparted the same processing safety performance and faster curing rate, better abrasion resistance and better wet skid resistance comparing with Si69.The compound containing Si747 showed higher Payne effect, but with the increasing of temperature the Payne effect was lowered. With the increase of the dumping temperature, better processing properties and mechanical properties were gotten for NR vulcanizates containing Si747. When the Si747 amount was 2.5phr, the compound had good filler dispersion and processing properties, the dynamic and static properties of vulcanizate was best.The effect of silica dispersing agents on properties of silica/carbon black filled NR showed that dispersing agents can lower the heat buildup of materials during mixing process, improve mobility. SEM and RPA showed, Payne effect was weaken and filler dispersion became better. Zinc soap dispersants HTX showed better dispersion effect among the whole dispersing agents. The use of dispersing agents extended the scorch time of compounds, improving the processing properties, especially zinc soap dispersing agents. After the adding of dispersing agents, the curing rate index slightly increased. Dispersing agents had little relationship with crosslink density. Dispersing agents improved the abrasion resistance of vulcanizates, lowering compression fatigue temperature and permanent deformation. Tear strength of vulcanizates with HST was much higher than other materials, which also had the minimum temperature rise during compression fatigue.