Surface Modification Of White Carbon And Its Application In Nature Rubber

Silica is the most widely used reinforcing agent in the field of rubber industry after carbon black.However,due to the surface of silica contains a large number of silicon hydroxyl groups,the polarity is great,and the compatibility with rubber matrix is poor,which leads to poor dispersion of silica in rubber,and ultimately limits the application of white carbon in rubber industry.Therefore,silica need to be modified when using it,and in the process of modification,the selection of dual agents is of great importance.Based on this,the research work of this paper will be carried out from the following three parts.Fristly,usingbis[?-?triethoxysilyl?propyl]tetrasulfide?Si69?,?-methacryloxypropyl trimethoxy silane?KH570?,ethyltrimethoxysilane?11-100?modified silica,and the modified silica were characterized by FTIR,TG,SEM.Then,the modified SiO₂/NR composites were prepared and characterized by rheometer,universal testing machine,RPA and SEM.The results show that after modified by coupling agent,the hydrophobic property of silica was improved,the particle size distribution became narrow,and the degree of agglomeration was improved obviously.The three coupling agents modified by Si69 had the best effect.Modified silica vulcanizates compared with the unmodified silica rubber elongation decreases,but the tensile stress increased.Among them,Si69 modified the largest increase,300% fixed extension of 90.12%.In addition,modified SiO₂/NR composite hardness,tear strength also increased significantly.The rolling resistance and heat generation of Si69-SiO₂/NR composites are the lowest.Secondly,from the first part of the study,we can see that the Si69 modified silica and Si69-SiO₂/NR composites have the best performance.Therefore,the optimum technological conditions of Si69 modified silica and the influence of-S4-in Si69 on the vulcanization characteristics and mechanical properties of natural rubber will be further investigated.The results show that the optimum conditions of Si69 modified silica as the reaction temperature is 55 ?,the reaction time is 4 h,the pH value is 7.When the amount of Si69 was 0.375 g,the modified silica had the best dispersibility.When the sulfur content is equal,with the decrease of Si69 content and the increase of sulfur?S?content,the maximum torque?MH?and the minimum torque?ML?are increasing,and the overall trend of the positive vulcanization time decreases;and the100% and 300% elongation stress and tensile strength of vulcanizate begin to increase and then decrease,and the elongation at break and tear strength tend to increase,and the hardness is little change;natural rubber reaction activation energy increased firstly and then decreased,the reaction activity first decreased and then increased.Finally,in order to make the silica has a good reinforcement and a certain anti-aging function.Using gamma aminopropyltriethoxysilane?KH550?as a bridge,on the surface of silica grafted phenolic antioxidant 3,5-tert butyl-4-hydroxy benzene acetic acid,preparation for anti-aging silica.The anti-aging silica is characterized by FTIR,TG,SEM.The old age to silica filled natural rubber,and to explore the dispersion and anti-aging effects of the modified silica in natural rubber.The results show that the compatibility and dispersibility of anti-silica with natural rubber matrix is better than that of unmodified silica.After the thermal aging,the rate of change of tensile strength and elongation at break of anti-aging SiO₂/NR is lower than that of unmodified anti-aging SiO₂/NR composites.The thermal oxidation activation energy of anti-aging SiO₂ vulcanizates is higher than that of unmodified SiO₂ vulcanizates.The anti-aging silica has no effect on the reaction of the free-cracking of the natural rubber vulcanizate and has a certain effect on the thermal aging process of the natural rubber vulcanizate.