| Styrene butadiene rubber(SBR)is one of the most widely used synthetic rubbers at present,with high moisture resistance and low rolling resistance of the overall performance,which can be used as a kind of excellent green tire tread material.Because of the low strength and the processing performance of rubber material,it is necessary to add filler to improve it.This paper focuses on the nano-reinforced technology of rubber,and the graphene-filled rubber composites were studied.Graphene is very easy to agglomerate due to its high specific surface area characteristics,the properties of the reinforced composites to a large extent with the interface combination of graphene and rubber matrix,in order to improve the defect that the graphene is easy to agglomerate,different functional groups are grafted on the surface of graphene in this paper.By combining molecular simulation and experiments,on the one hand,we study the influence mechanism of graphene with special chemical functional groups on interfacial microstructure and binding properties between graphene and SBR.On the other hand,the effects of the molecular structure,the polarity and the content of styrene of SBR on molecular motion of the composite were studied.It provides a new idea for the nano-reinforced rubber and the preparation of rubber composites with high performance.In the simulation,by the means of molecular simulation methods,-NH2 and-COOH chemical functional groups are grafted on the surface of graphene,and the changes of glass transition temperature of chemically modified graphene/SBR composites were studied.We analyze molecular dynamic(MD)results,and the glass transition temperature(Tg)was obtained by using the specific volume-temperature relationship.It was found that the cohesive energy density(CED),fractional free volume(FFV),mean square displacement(MSD)and molecular chain diffusion coefficient(D)of the composites increased with the rising of temperature and a significant transition occurs at the Tg.The results show that the chemical modification of graphene may be an effective method to improve the interfacial bonding property between the matrix and the filler when graphene as rubber reinforcing filler.In the aspect of rubber matrix,using molecular dynamics(MD)method,we construct the all-atom model of SBR and graphene composites with different molecular chain structures and analyze the mean square displacement,diffusion coefficient and mean square radius of gyration.The results show that the styrene content,branched structure and graft modification of the SBR molecular chain affect the activity of the polymer chain,which may affect the final properties of the grapheneh/SBR composites.In recent years,the ring-opening metathesis polymerization has attracted the attention of various industries of the polymer,the product prepared by ROMP is a kind of thermoplastic engineering plastic used to produce shatterproof bottle,syringes,LED and so on,which has high transparency,chemical resistance and best overall performance after hydrogenation reactions.In this study,three kinds of samples of E48R,480R and 330R of Zeon Company were tested by IR,thermal analysis,hydrogen or carbon nuclear magnetic resonance.The possible molecular structures and their microstructures were analyzed.Based on the molecular dynamics simulation,the relationship between the structure of the polymer monomer and the density and glass transition temperature of these three Cyclic Olefin Copolymer(COC)samples was established,and it provides the basic data for its production.. |
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