Synthesis Of Novel Macromolecular Silica Coupling Agents And Their Application In Styrene Butadiene Rubber

In recent years,as a kind of "green filler",silica can reduce the rolling resistance and improve the wet skid resistance of the tire.It is gradually replacing carbon black to become the main filler in the tire industry.However,the surface of silica has strong polarity,resulting in poor dispersion in non-polar rubber.At the same time,the silicon hydroxy groups on the surface of silica are prone to form hydrogen bonds,making them easy to agglomerate after being disperse.At present,in order to improve the dispersibility of silica in rubber matrix,silane coupling agent is often used to modify the surface of silica.After the modification,the silica has good dispersing effect and the comprehensive performance of the composite material is improved.However,the silane coupling agent could generate small molecule alcohol during the process of modifying the silica,which causes the emission of VOC,it's not conducive to environmental protection.In this paper,the free radical grafting method was used to synthesize macromolecular coupling agent,low molecular weight polybutadiene grafted maleic anhydride(LPB-g-MAH),and the effects of temperature,initiator,maleic anhydride and solvent amount on the grafting reaction were studied.LPB-g-MAH was applied to silica modified,the results of infrared spectroscopy(FTIR)and thermogravimetric analysis(TGA)showed that LPB-g-MAH was successfully grafted on the surface of silica.Subsequently,the silica was modified by LPB-g-MAH in one-step and two-step processes to prepare ESBR/silica nanocomposite.The results of RPA and TEM showed that the addition of LPB-g-MAH can make the dispersion of silica more uniform and the Payne effect reduced.At the same time,the curing time of the ESBR/Silica nanocomposite is shortened,the rolling resistance is reduced,the mechanical properties are improved,and the two-step method is superior to the one-step method.The free radical emulsion polymerization method was used to synthesize macromolecular coupling agent,low molecular weight poly(diethyl itaconate/isoprene)(LPDEII).By regulating the dosage of initiator and molecular weight regulator,the Mn of LPDEII was controlled below 10000.The hydrogen bond between ester group of LPDEII and silica was used to modify silica,to prepare ESBR/Silica nanocomposite.The results of RPA and TEM indicate that the addition of LPDEII could not improve the dispersibility of silica.Because hydrogen bonding is too weak,achieving the modification effect needs a large amount of hydrogen bonds.The number of functional groups in LPDEII is not sufficient.Based on these,we chose bio-based monomer,glycidyl methacrylate(GMA),as a silica modifier,to prepare the ESBR/silica nanocomposite.The results of RPA and TEM showed that the addition of GMA can make the dispersion of silica more uniform and the Payne effect weakened.At the same time,the curing time of the ESBR/Silica nanocomposite is shortened,the rolling resistance is reduced,and the mechanical properties are improved.And under the experimental formula,the optimal amount of GMA is 10%of silica.