The Preparation Of Graphene/Silica/SSBR Composites On Comprehensive Properties : Molecular Simulation And Experiment

Rubber,as an indispensable material for tire industry,possesses unique viscoelasticity.However,the pure rubber is difficult to meet its practical requirement.Therefore,it is necessary to add filler to reinforce the rubber.The silica（SiO₂）is widely combined with solution-polymerized styrene-butadiene rubber（SSBR）to prepare SiO₂/SSBR composites for tire tread compound,which can ameliorate its wet skid resistance and rolling resistance.It is of great difficulty for SiO₂/SSBR composites to provide the comprehensive requirements for high-property of tire with better durability,wear resistance and thermal conductivity.According to its large specific surface area and outstanding mechanical properties,and especially thermal conductivity,the addition of graphene（GE）can enhance the relevant properties of SSBR composites.It has the potential to compensate for the shortcomings of the wear resistance and thermal conductivity of SiO₂.However,SiO₂ and GE are easily self-aggregates and have inferior compatibility with the SSBR matrix.The dispersion of fillers and the interfacial property of composites need to be deeply discussed.In this study,a multiple filler/SSBR model was built via molecular dynamics（MD）simulation.The interfacial interaction of filler/SSBR systems was predicted through equilibrium molecular dynamics simulation.A nonequilibrium molecular dynamics simulation was used to forecast the thermal conductivity（TC）.Based on the simulation prediction,reduced graphene oxide grafted with silica（r GO-g-SiO₂）was prepared by hydrosilylation.Then,the performance of the r GO-g-SiO₂/SSBR composites was measured,including static,dynamic mechanical and thermal properties,which were found to validate the MD simulation results.The specific research contents include the following two parts:（1）During the MD simulation,the r GO-g-SiO₂ was designed and the multiple filler/SSBR models were built.They are SiO₂/SSBR system formed by unmodified SiO₂ and SSBR,SiO₂-K/SSBR system formed by3-（trimethoxysilyl）propyl methacrylate（KH570）molecular modified GE and SSBR,r GO/SiO₂/SSBR system formed by blending SSBR with unmodified r GO and SiO₂,r GO-T/SiO₂-K/SSBR system formed by blending SSBR with 1,1,3,3-tetramethyl-1[（2-triethoxysilyl）ethyl]-disiloxane（TTED）molecular modified GE and SiO₂-K,r GO-g-SiO₂/SSBR system formed by blending SSBR with r GO-g-SiO₂.The MD simulation results showed that compared with other filler/SSBR systems,the r GO-g-SiO₂/SSBR system had the higher binding energy,the lower free volume fraction and diffusion coefficient,indicated a better interfacial strength between the r GO-g-SiO₂ and SSBR molecular chains,which is beneficial to improve the mechanical properties of SSBR composites.On the other hand,compared with the r GO/SiO₂/SSBR and r GO-T/SiO₂-K/SSBR systems,the thermal performance of the r GO-g-SiO₂/SSBR system including thermal conductivity and thermal diffusivity coefficient also showed a certain increase.The phenomenon is mainly attributed to the lower the interfacial thermal resistance of the r GO-g-SiO₂/SSBR system,which increased the interface phonon matching,also improved the thermal conductivity of r GO-g-SiO₂/SSBR composites.（2）According to the design idea of the molecular structure of the above filler,the x-r GO-g-SiO₂（x represents the weight percentage of r GO in r GO-g-SiO₂）was synthesized by hydrosilylation.Also,the multiple filler/SSBR composites were prepared,namely r GO/SiO₂/SSBR,r GO-T/SiO₂-K/SSBR and x-r GO-g-SiO₂/SSBR composites.The mechanical and thermal properties of various SSBR composites were studied.The results show that the x-r GO-g-SiO₂/SSBR composites have the better comprehensive properties,which are consistent with the MD simulation.In particular,the reinforcing index and thermal conductivity of 1.5%-r GO-g-SiO₂/SSBR composites are found to be 168.7%and 114.0%higher than that for 1.5%-r GO/SiO₂/SSBR composites（physical mixture）,respectively.The loss factor for 1.5%-r GO-g-SiO₂/SSBR composites is enhanced by119.7%at 0?°C and decreased by 21.9%at 60?°C,which indicates optimal wet-skid resistance and rolling resistance compared with 1.5%-r GO/SiO₂/SSBR composites.And the Akron wear volume and compression heat generation decreased by 28.9%and 33.6%,respectively.The wear volume and heat build-up of 1.5%-r GO-g-SiO₂/SSBR composites are separately declined by 28.9%and 33.6%compared with1.5%-r GO/SiO₂/SSBR composite.The reinforced integrated performance is promising for the potential application of the fabricated x-r GO-g-SiO₂ as a filler for SSBR composites,which is agreed well with MD simulation predictions.The research method of MD simulation combined with experiment provides a new way for the design and preparation of rubber nanocomposites.