Research On Filler Network And Dynamic/Static Mechanical Properties Of SBR Composite

Filler network is a very important factor that influences the dynamic/static mechanical properties of rubber composites. In-situ modification of silica filled SBR is one development direction of the new type green tire. Because the method can decrease the rolling resistance and increase the wet skid resistance properties of tread rubber in tires without decreasing the wear resistance. In this paper, the influence of in-situ modification of Si69 to the network of SSBR and ESBR composites, and effect of glass bead to the performance of silica filled SSBR composites is studied by the numbers. The results indicate that in-situ modification of Si69 can improve the dispersion of silica in SBR and strengthen the silica/rubber matrix interface, thus improve the dynamic/static mechanical properties of the composites. Besides, the glass bead can improve the processing performance of the composites. The work is as follows:1. The influence of the content of silica, SBR kind and in-situ modification of Si69 to the network is studied, which bases on the characterization of the network of silica filled SSBR/ESBR by means of bound rubber, TEM, SEM, GPC, RPA and so on. The results indicate that, the network filler network begins to form when the filler overruns thecritical content, and the network of 50 phr and 70 phr silica filled SBRcompounds without modification is mainly composed of silica particles (rigid node), so the Payne effect is obvious, and so do the G' of 70 phr silica filled compounds increases due to the conglomeration of the filler in the temperature sweep. After the in-situ modification of Si69, the dispersion of silica is improved, and the network is mainly composed of flexible node, and in-situ modification of Si69 can improve the stability of network at high temperature, thus the Payne Effect is obviously weakened and the Mooney Viscosity is decreased, therefore the processing performance of the compounds is improved. Compared to the compound without in-situ modification, the compound with in-situ modification of silica exhibited higher tanδat low strains and lower tanδat high strains, which dues to the dispersion of filler is improved by in-situ modification.The results of bound rubber indicate the higher molecule weight SBR molecules first absorb on the surface of silica particles. And in-situ modification forms chemical bonds in the interface by the couple reaction between Si69, silica and rubber. Furthermore, Si69 brings a small quantity of crosslinking in the rubber matrix, which obviously increases the bound rubber content.The bound rubber content of silica/SSBR compounds is higher than silica/ESBR compounds, which dues to the combination between silica and SSBR is firmer than silica and ESBR.By fitting G'-strain curves of the compounds and calculating the factor in the equation, the results ofγ'c indicate that the network becomes more developed with the increasing of silica content, and in-situ modification decreases the development of the network. But the results of the fractal dimension of network show that the Kraus Model is not very appropriate to describe the silica/SBR compounds.2. The influence of in-situ modification of silica with Si69 to the structure and performance of vulcanizate is studied. The results indicated that, in-situ modification of Si69 improves the dispersion of silica in vulcanizate and decreases the hardness of vulcanizate. At the same time, the modification increases the stress at 300% strain of vulcanizate, decreases the dynamic hysteresis at time after time strain sweep and wide frequency range at large strain in 60℃, in other words, decrease the dynamic thermogenesis. The results of DMTA indicate that the modification increases the dynamic hysteresis around 0℃, thus improves the wet skid resisitance of the material.3. The influence of glass bead to the processing and dynamic/static mechanical properties of the silica/SSBR composites is studied. The results show that the incorporation of glass bead have little effect on the Mooney Viscosity and dynamic module of the compounds; the mechanical properties and Akron abrasion property of the vulcanizate almost keep the same. The dynamic module of the vulcanizate is increased, and with increasing frequency and strain, the dynamic hysteresis is increased.