The Preparation And Properties Research Of Amino-functionalized Graphene/Polyurethane Composites

Graphene is a new material was found after the fullerene, carbon nanotubes, which possesses numerous unique properties, such as:high specific surface area, good thermal conductivity, electrical conductivity. It not only has been the focus of researchers, but also has been widely used in preparation of composite material. However, it has some drawbacks in preparing the polymer/graphene composite material, like tendency of gathering together, low reaction activity and difficult compatibility with organic polymer. For this problem, graphene oxide is modified by non-covalent bonding method and covalent bonding method respectively in this paper, and studying the effect of graphene on the mechanical properties of composite materials which were prepared through adding one kind of functionalized graphene to waterborne polyurethane. The main contents of this thesis are as follows:1. Non-covalent modification of graphene. The reaction between the cationic waterborne polyurethane and graphene oxide was prepared according to the mixed ratio of 1:10, followed by the reduction reaction with hydrazine hydrate, finally the cationic functionalized grapheme was obtained. The products obtained were dispersed in DMF, acetone and ethanol through ultrasonic stripping, it can be observed that the functionalized graphene dispersed in this three kinds of organic solvents existed stable. In addition, product structure was characterized by XRD, Raman, TEM and other means, the results showed that the cationic waterborne polyurethane adsorbed on the surface of graphene successfully.2. Covalent modification of graphene. Functionalized graphene containing a primary amine group (N-FGNs) on the surface was prepared through the reaction between 2,4-toluene diisocyanate (2.4-TDI) and the graphene oxide first, and followed by reduction reaction with hydrazine hydrate. The structures of the product were characterized through XRD, XPS. The results showed that -NCO groups were grafted on graphene oxide surface by formation of urethane bonds through reacting between 2,4-toluene diisocyanate (2.4-TDI) and the hydroxyl groups on graphene oxide, the graphene surface contained primary amine group after the reduction reaction with hydrazine hydrate.3. Preparation of the functionalized graphene/polyurethane composites. Waterborne polyurethane prepolymer was prepared with PTMG, IPDI, DMPA as raw materials, and N-FGNs were added to the prepolymer according to the different proportion, then amino fumctionalized graphene/waterborne polyurethane composite was prepared through triethylamine neutralization reaction. The results of TEM, SEM showed that the amino functionalized graphene can be uniformly dispersed in the waterborne polyurethane and it has excellent compatibility with waterborne polyurethane. Through testing the mechanical properties of the composites, the results showed that the addition of the amino functionalized graphene has an effect on tensile strength and the storage modulus of waterborne polyurethane, they also indicated that the tensile strength of the composites was enhanced obviously with the increase of amino functionalized graphene content. When the N-FGNs content was lwt%, the tensile strength of the composites material increased by 77% compared to pure PU, the storage modulus of E’ increased by 930%, the elongation at break decreased only by 4%.