Fabrication And Characterization Of Carbon Nanotubes/Polymer Composites

In recent years, tremendous attention about the research of nano-materials has been focused on carbon nanotubes(CNTs). Because of their unique physical, chemical and mechanical properties, CNTs have a high value of science research and extensive potential of application in many fields, and are ideal filler of composites. Now, there are two main obstacles in the way of CNTs' application. First, due to the van der Walls forces, CNTs can't dissolve in almost all solvents and homogeneous dispersions in composite are not easily obtained; second, with the smooth surface, the interfacial bonding between CNTs and matrix are very weak and the load can't transfer from the matrix to CNTs effectively. To overcome these two challenges, some research works we did in these following issues are presented in the paper.1. Covalent Functionalization of CNTs with Polystyrene (PS )Interaction between CNTs and benzoyl peroxide (BPO) has been research firstly. With the results of FTIR and TG, we prove that there is an alkene addition-liked reaction happened between the free radicals from BPO and CNTs. In the traditional theory of free radical polymerization, the activity of radical doesn't change with the increase of propagating chain. Since the free radical generated from BPO can add to CNTs directly, so do the propagating radical during polymerization . Based on this, we fabricate PS-modified CNTs in situ polymerization. All characterization results suggeste that the CNTs and PS are combined by covalent bonding.2. Non-covalent Functionalization of CNTs with PSNon-covalent Functionalization of CNTs with PS are prepared by two soft templating methods: miniemulsion and emulsion polymerization. In the composite latex prepared by emulsion polymerization, CNTs are covered with nanometer thin film of PS, while CNTs are covered with micro spheres of PS in the latex synthesized by miniemulsion polymerization. Due to the non-covalent modification, the interaction between CNTs and PS are very weak, and the polymer will shed because of the solvent affection. To overcome this difficulty, we add cross-linked reagent divinylbenzene (DVB) to monomer, and PS are fixed on the surface of CNTs by cross-linked entanglement.3. Enhancement of Functionalized CNTs in CompositesCNTs/PS composites are fabricated by mixing PS with two kinds of functionalized CNTs in melting processing. The stress versus strain curve indicated the compositeshave been reinforced by CNTs and the mechanical properties such as tensile strength, bending strength and elongation at break have been improved obviously. The results suggeste both kinds of functionalization method can improve the dispersion of CNTs and enhance the interfacial bonding between them and matrix.