Rubber/graphene Nanocomposites: In-Situ Interfacial Modification And Slurry Compounding Method

Graphene has been widely used as a new filler to reinforce rubber due to its excellent mechanical propertis. But how to prepare rubber/graphene nanocomposites via the facile mechanical compounding method and how to imporove the interfacial interactions between graphene and nonpolar rubber are two important issues to be solved in order to implement the reinforcement effect of graphene. The two issues are the main research topic in this study.First, a new method consists of rubber latex compounding and in-situ interfacial modification was employed to prepare modified styrene-butadiene rubber(SBR)/graphene oxide(GO) nanocomposites. Oleylamine and octadecylamine were employed as the modifiers. FTIR, Raman and XPS characterizations demonstrated that both alkylamine grafted onto GO surface and edge via covalent bonding and ionic bonding, respectively. GO was partly reduced during the alkylation process. The in-situ grafting of alkylamine could significantly improve the dispersion of GO in SBR matrix and their interfacial interaction. The curing information demonstrated that the grafting of both alkylamine could largly accelerate the curing rate but deteriorate the cross-linking density of composites. Mechanical property mearsurments revealed that the in-situ interfacial modification could largely improve the tensile strength, tensile modulus, tear strength and shore A hardness for composites. Dynamic mechanical analysis revealed that after in-situ modification, the storage modulus of composites increased but the value of loss factor decreased; The Mooney-Rivilin equation and Nint-Strain equation were employed to quantify the interfacial interactions for composites, the results demonstrated that composites modified by oleylamine possessed the strongest interfacial interaction among the three systems. Composites modified by octadecylamine also had stronger interfacial interactions than the one without modification. Finally, FTIR results for model compound demonstrated that the existence of interfacial cross-linking in oleylamine modified system was the reason for its best mechanical properties.Second, the ―slurry compounding‖ method was employed for the first time to prepare rubber/GO nanocomposites. We used the solvent-exchange method to prepare GO slurry and bis(triethoxysilylpropyl)tetrasulfide(Si69) modified GO slurry with a high concentration about 40~50 mg/m L and acetone was employed as the solvent. XRD patterns revealed that the actone molecules could intercalate into the interlayer of GO to expand the interlayer distance. The addition of Si69 could further expand the interlayer distance of GO and Si69 could graft onto GO surface via silanization reaction with the hydroxyl groups of GO. The as prepared slurry could direct compounding with rubber on a conventional two-roll milling to fabricate nitrile rubber(NBR)/GO nanocomposites. The results of SEM and TEM revealed that slurry compounding method implemented the nano-scale dispersion of GO but the aggregation of GO was almost inevitable. The addition of Si69 could significantly improve the dispersion of GO in NBR matrx and their interfacial interaction. Mechanical property measurements revealed that the addition of GO could largely improve the tensile strength, thensile modulus, tear strength and dynamic strorage modulus. Finally The Mooney-Rivilin equation and Lorenz-Park equation demonstrated that Si69 could strengthen the interfacial interaction between GO and NBR.