Design And Synthesis Of Isolating Modifiers And Study On The Dispersibility Of Silica In Rubber

Silica is a renewable inorganic powder filler,which is widely used in the rubber industry because of its excellent reinforcing properties.However,there are many highly active hydroxyl groups on the surface of silica,and the original particle size is only 20-50 nanometers.Therefore,silica is easy to aggregate and has a strong polarity,so it is difficult to uniform disperse in the rubber matrix,resulting in poor overall performance,so it cannot meet product requirements.In this paper,in the first part,we first proposed the direct modification of silica with polyoxyethylene(20)sorbitan monolaurate(TWEEN-20),and studied the modification mechanism.In the second part,we used TWEEN-20 and silane coupling agent(Si69)to modify silica to prepare high-performance rubber nanocomposites.In the third part,we used isolation modifiers of different lengths to modify the silica,and investigated the effect on the properties of the rubber composites to obtain the best isolation distance,and finally we studied the mechanism.The main findings are as follows:(1)In this work,we firstly successfully used TWEEN-20 to direct modify silica.According to analysis the characterization results of FTIR,TGA,and XPS,they prove that the terminal hydroxyl groups on TWEEN-20 can not only chemically react with the silanol groups on the surface of silica,but also the ether bonds on the TWEEN-20 molecular chain of can generate hydrogen bonds with the silanol groups on the silica surface.The long fatty chain on TWEEN-20 can coat on the surface of silica,reduce the polarity of silica and increase the compatibility with the rubber matrix.In addition,according to XRD and BET results,it proves that the basic structure of silica did not change before and after the modification,so it did not affect the reinforcement performance.(2)We firstly used TWEEN-20 and silane coupling agent(Si69)to modify silica and prepare high-performance rubber composites.TWEEN-20 can efficiently disperse silica in the rubber matrix,and Si69 can chemically react with rubber molecular chains to form chemical bonds.According to the analysis of test results,the dispersion of silica and the static mechanical properties and dynamic heat generation of rubber composites are better than that of modified with Si69 alone.In addition,due to the reduction in Si69,it reduces VOC release and improves processability.(3)We firstly synthesized different isolation modifiers with similar structures but different lengths(diglycidyl ether),and used FTIR and 1HNMR to characterize the structure of the synthesized substances.Then we used isolation modifiers to modify silica and to prepare rubber composites.We measure the radius of gyration by Materials Studio(MS),and determine the best isolation distance according to the effects on the comprehensive performance.When the radius of gyration reaches 0.82nm,the silica dispersion,static mechanical properties,and dynamic thermomechanical properties reach the best and then continue to increase the radius of gyration,the overall performance changes little.