| The dispersion of silica has a great influence on the properties of its reinforcing rubber.In order to increase the dispersion of silica in composites,functionalized SSBR was grafted to the surface of silica by high speed mixer,colloid mill mechanochemical methods,and was characterized by FTIR,TG,BET,etc.Grafted silica was used to fill SSBR.The dispersion of grafted silica was analyzed by RPA?SAXS?TEM and bound rubber.Furthermore,the mechanical properties and dynamic mechanical properties were studied.The main contents and achievements are as follows:Adding silane coupling agent to improve the dispersion of silica in the rubber matrix directly in industry has limited effect and will cause fatal defects such as coking?elongation at break reduction and porosity increase.In this paper,SSBR-SiC13(10K)was synthesized by anion polymerization,and then grafted onto the surface of silica by the reaction of chlorosilicone bond and silicon hydroxyl group by a high-speed shear mixer.The graft percentage was 8.09%,the graft density was 3.75×10-3nm-2,and the graft efficiency was 95.2%.The dispersion of SiO2-g-SSBR-SiCl3(10K)in SSBR was improved,the agglomeration of silica was weakened,the filler-filler network was destroyed,and the radius of silica aggregates in SSBR was reduced from 26.91nm to 25.99nm.Compared with the unmodified silica filled SSBR,the rolling resistance of the grafted silica filled composites decreased by 11%,the wetting resistance increased by 36.0%,and the tensile strength increased by 21.5%without decreasing the elongation at break.Colloid mill can be used to prepare macromolecular grafted silica in large quantities,which provides the possibility for industrialization.Firstly,three macromolecular modifier SSBR-SiC13(80K)?SSBR-(CH2)3Si(OCH3)3 and SSBR-g-MPTES were synthesized by anion polymerization and "click" chemistry.Then,the Si-Cl?-OCH3 and-SH bonds in the three macromolecular modifiers were chemically bonded with the silicon hydroxyl on the surface of silica by colloid mill,with grafting percentages of 0.54%,1.00%and 7.77%,and grafting densities of 0.38×10-3,0.61×10-3 and 5.77×10-3nm-2,respectively.The dispersion of modified silica in SSBR matrix was significantly improved,the agglomeration of silica was weakened,and the radius of the aggregate decreased from 26.91nm to 26.30nm,26.32nm and 25.99nm respectively.Compared with unmodified silica,the tensile strength of SiO2-g-SSBR-SiCl3(80K),SiO2-g-SSBR-(CH2)3Si(OCH3)3 and SiO2-g-SSBR-g-MPTES fill SSBR increased by 23.8%,17.4%and 24.78%,respectively.The tear strength increased by 11.3%,12.1%and 34.0%,respectively.The wet resistance increased by 55.6%,63.0%and 77.8%,and the rolling resistance decreased.In this paper,the rubber matrix was mixed with modified silica in colloidal mill.The results show that the dispersion of silica in SiO2-g-SSBR-(CH2)3Si(OCH3)3/SSBR and SiO2-g-SSBR-g-MPTES/SSBR composites is better compared with the traditional dry mixing method,and the compatibility with the rubber matrix is obviously improved.The tensile strength and tear strength of the composites increased by24.2%and 9.6%respectively,and the crosslinking density decreased.At the same time,the rolling resistance of the composite remained about the same,and the wet resistance increased by 102.4%. |
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