Application Of Polymer Latex Modified Nano-silica In Tire Tread Rubber

Tires play buffering,transmitting traction and braking force roles in the driving of the car,and have gradually developed from the primitive wood to elastomer.With the development of the economy and society,energy and the environment problems are becoming increasingly serious,people have begun to pay attention to high-performance tire which is safe,energy-saving and environmentally friendly.The goal of this work is to balance properties among the rolling resistance,wet skid resistance and wear resistance,which is called"Magic triangle".Based on the compatibility principle of macromolecular chains and the entanglement between macromolecular chains,nano silica(SiO2)coated with polymer latex was designed and prepared,and the "Magic triangle" properties of tire tread rubber prepared with SiO2 were studied.The relationship between structure and properties was discussed in order to design and synthesize surface modified nano silica with application prospect.The main research contents and results are as follows:1.Preparation of modified nano SiO2 coated with chloroprene rubber latex and its application in tread rubberA liquid phase in situ modification method was used to synthesize hexamethyl disilazane(HMDS)modified nano SiO2(denoted as HB105,HB110,HB120 according to different HMDS content).Chloroprene rubber(CR)latex was used to modify the above nano SiO2,and the sample obtained by spray drying was blended with solution polystyrene-butadiene rubber(SSBR)and butadiene rubber(BR)according to a certain formula ratio,and the influence of dynamic properties and static properties of the composite material were studied.Studies have shown that nano SiO2 modified with HMDS can significantly improve the wear resistance and wet skid resistance of composite materials,but it also increases rolling resistance and is not an ideal tread rubber filler.It is believed that CR latex has electrostatic adsorption with SiO2 in the water phase.After spray drying,the CR molecular chains are curled and coated on the surface of nano SiO2.The strain sweeping shows that the Payne effect for composites are reduced after modifying CR,and the SiO2 dispersion is improved.The coating layer of CR reduced the surface polarity of SiO2 and reduces the probability of direct contact between SiO2 particles,thereby weakening the degree of flocculation of nano SiO2 in the rubber matrix.The tensile strength of HB 110-2.5%CR/SSBR/BR is 20.4%higher than that of unmodified composite materials.The wet skid resistance is increased by 26.7%,and the wear resistance is increased by 7.3%without increasing the rolling resistance2.Preparation of nano SiO2 modified by ethylene-vinyl acetate copolymer latex and its application in tread rubberHB110 and HB120 nano SiO2 were synthesized by liquid phase in situ method,on this basis,ethylene-vinyl acetate copolymer(EVA)latex was modified by gradient.The nano SiO2 obtained by spray drying was mixed with SSBR and BR in mixer to prepare composites,then dynamic and static mechanical properties of composites were studied and analyzedTEM showed that the particle size of the nano SiO2 increased slightly after modification.As the amount of EVA modification increased,the specific surface area gradually decreased and the number of surface hydroxyl groups decreased,which can shield the polarity of silicon hydroxyl groups to a certain extent and enhance the compatibility of nano SiO2 and rubber matrix.The strain sweeping results show that the modified nano SiO2 has improved dispersion in the rubber.DMA curves show that the interface between the filler and the rubber is improved,and the wet skid resistance of composites after modification(HB120 series)are significantly improved.HB 120-7.5%EVA/SSBR/BR reduces rolling resistance by 11.3%and improves wet skid resistance by 23.0%without sacrificing wear resistance3.Preparation of nano SiO2 modified by functional ethylene-vinyl acetate copolymer latex and its application in tread rubberOn the basis of the second part of the research content,epoxy-terminated EVA(EVA-E),carboxy-terminated EVA(EVA-C),amino-terminated EVA(EVA-A)and hydroxyl-terminated EVA(EVA-H)modified nano SiO2 were further designed and synthesized,respectively.The effect on the properties of composites was studied.The properties of SSBR/BR composites prepared by polymer-modified nano SiO2 were compared with commercially available nano SiO2(1165MP)The results showed that the macromolecule chains coated on the surface of nano silica avoided direct contact between nano silica particles,and the tendency of agglomeration was weakened.Hydrogen bonds are formed between the polar groups contained in the functional EVA and the silicon hydroxyl group,which can inhibit the agglomeration between the silica particles.Combined with the SEM images and strain sweeping results,it is confirmed that the dispersibility of modified nano SiO2 is improved.Compared with HB100/SSBR/BR,the modulus of EVA-E modified composite is slightly reduced,the wet skid resistance is higher,and the wear resistance can be increased by 31.0%.For HB 120-2.5%EVA-C/SSBR/BR composite,wet skid resistance increased by 14.5%,wear resistance increased by 25.8%,tensile strength and elongation at break reached the best value at the same time.HB 120-5%EVA-A/SSBR/BR has both high wet skid resistance and low rolling resistance,accompanied by equivalent wear resistance to unmodified composite materials.The dynamic mechanical properties of EVA-H modified composite materials are good,and the wear resistance decreases as the amount of EVA-H increases.Compared with 1165MP/SSBR/BR,the modified material has better wear resistance,which up to 41.0%higher.The wet resistance is equivalent or higher than 1165MP/SSBR/BR without significantly increasing rolling resistance.HB120-1%EVA-H/SSBR/BR composite material has 32.7%higher wear resistance,26.9%lower rolling resistance and 3.3%higher wet skid resistance than 1165MP/SSBR/BR,which has application potential.The preparation process is simple,easy to operate,environmentally friendly,and suitable for large-scale production.The research results provide theoretical support to some extent and basic data for industrial applications.