Study Of Preparation Of Modified Nano Silica And Properties Of Modified Nano Silica Filled Rubber

Tire tread rubber filled with silica can improve the mechanical properties,wet skid resistance and reduce rolling resistance of rubber composites.However,the silica with larger particle size and smaller specific surface area has weaker interaction with rubber,which is not conducive to the reinforcement.At the same time,owing to lots of hydroxyl group of silica surface,silica and non-polar rubber matrix have poor compatibility.The strong filler network structure have an adverse effect on the performance of rubber.Therefore,it is necessary to optimize the preparation process of silica to prepare silica products with small particle size and large specific surface area.Furthermore,silica must be modified to reduce the number of surface hydroxyl groups and improve the dispersion in rubber matrix.In the paper,the preparation method of silica was improved,ethanol is introduced at the precipitation reaction stage and the aging stage.Silica with a small specific surface area and a large particle size was prepared.Then vinyltriethoxysilane modified silica(VTES-silica)and y-mercaptopropyltriethoxysilane modified silica(MPTES-silica)were obtained by adding vinyltriethoxysilane(VTES)and y-mercaptopropyltriethoxysilane(MPTES)respectively on the basis of the preparation process of silica.The structure and morphology of different silica samples were characterized by TEM,BET,DLS,FT-IR,TGA.Compared with the commercial silica Zeosil(?)1165MP,the performance of different fractions of silica,VTES-silica,and MPTES-silica filled SSBR/BR composites(silica-SSBR/BR,VTES-silica-SSBR/BR,and MPTES-silica-SSBR/BR)were studied,respectively.The study is as follows:(1)Silica for green tire rubber was prepared from water glass using sulfuric acid and citric acid solutions.The effect of additive ethanol,macrogol 6000(PEG-6000)and cetrimonium bromide(CTAB)on the silica was studied.The appropriate amount of ethanol was added into silica slurry after the precipitation reaction was completed.The effect of the aging time on the silica product was investigated.The results showed that ethanol as the additive and aging for 2 h were the optimum reaction condition.Initial particle diameters of the prepared silica had a normal distribution.The silica with a small average particle diameter of 15 nm,DBP oil absorption value of 2.1 ml/g,BET specific surface area of 239 m2/g and pore size of 34.7 nm was prepared.The primary aggregate peak of the silica was 150 nm.Compared with commercially available silica Zeosil(?)1165MP,optimum curing time(t90)of silica-SSBR/BR composites at filler content of 70 phr was significantly shorter and the curing rate was faster.Tensile strength and reinforcing index(RI)of silica-SSBR/BR composites were higher.Silica-SSBR/BR composites exhibited weaker filler network,better wet skid resistance and lower rolling resistance.The heat build-up of silica-SSBR/BR and Zeosil(?)1165MP-SSBR/BR was nearly equal.(2)VTES-silica was prepared adding the coupling agent VTES on the basis of the preparation of silica.The hydrophobicity of VTES-silica increased.The relationship between the content of filled VTES-silica and the properties of SSBR/BR composites was investigated.It was found that VTES-silica-SSBR/BR composites at filler content of 80 phr shown high the crosslink density,strong tensile strength,good wet skid resistance and low rolling resistance.Compared with Zeosil(?)1165MP-SSBR/BR,VTES-silica-SSBR/BR composites exhibited slightly higher heat build-up value,little difference in tensile strength,higher elongation at break,better dispersion of filler,better wet skid resistance and lower rolling resistance.(3)The effect of MPTES-silica content on MPTES-silica-SSBR/BR composites was studied.The results shown that MPTES-silica-SSBR/BR composites at filler content of 70 phr had the strongest tensile strength and the best wet skid resistance and lowest rolling resistance.Compared to Zeosil(?)1165MP-SSBR/BR,MPTES-silica-SSBR/BR composites exhibited higher heat build-up value,and stronger tensile strength,higher elongation at break,lower rolling resistance and better wet skid resistance.