| Carbon nanotubes (CNT) have attracted considerable and increasing interests since their discovery because of their unique architecture and remarkable physical and chemical properties. CNT are considered to be the most promising candidates as ideal reinforcing fillers in high strength, light weight polymer nanocomposites. Epoxy resin is an important and versatile class of polymer materials, which is receiving steadily increasing attention and becoming an important composites matrix due to its superior mechanical properties, high adhesive and low curing contractibility. However, conventional epoxy resin exhibits poor thermal stability at high temperature, mechanical strength and toughness, which limit their applications. Aiming at the deficient properties, many investigations on modification of epoxy resin is always to improve the properties of epoxy resin without substantially damaging other properties.In this paper, multi-walled carbon nanotubes (MWNT) were modified by different chemical methods. And different MWNT were used as fillers to prepare MWNT/epoxy resin composites. The effect of MWNT on mechanical properties, electrical properties, thermal stability and curing process of epoxy resin was investigated. The probability of aromatic amino MWNT used as curing agent of epoxy resin was elementarily studied.1. Aromatic amino of MWNT and the reaction with epoxy resinThe surface of MWNT was grafted with 4,4’-Diaminodiphenyl sulphone (DDS), which was confirmed by Fourier transform infrared spectroscopy (FTIR). In-situ FTIR was used to characterize the reaction between amino MWNT and epoxy resin. The results showed that amino MWNT reacted with epoxy resin.2. Preparation and properties of MWNT/epoxy resin composites Different kinds of MWNT were used as fillers to prepareMWNT/epoxy resin composites. A series of testing methods, such as dynamic mechanical analysis (DMA), thermo gravimetric analysis (TGA), mechanical properties test, conductivity measurement etc, was used to study the properties of MWNT/epoxy resin composites. The dispersion of amino MWNT in epoxy resin was observed by Field-Emission Scanning Electron Microscopy (FESEM). The results showed that amino MWNT had good dispersion in epoxy resin matrix. The mechanical properties of epoxy resin were improved owing to the addition of MWNT, e.g., the impact strength of amino MWNT/epoxy resin composites reached 8.26KJ/m2, which was 50% higher than that of pure epoxy resin, and their tensile strength was up to 62.05MPa. Dynamic mechanical analysis (DMA) showed that glass transition temperature of epoxy resin increased up to 25℃. Amino MWNT could obviously decrease the volume resistivity of epoxy resin. Thermo gravimetric analysis (TGA) showed that MWNT/epoxy resin composites, carboxylic MWNT/epoxy resin composites and amino MWNT/epoxy resin composites had an increased thermal stability compared with pure epoxy resin.3. Study on the effect of MWNT on the curing process of epoxy resinThe Cure kinetics of epoxy resin composites containing MWNT was measured by non-isothermal DSC. The results showed that amino MWNT could enhance the cure reaction of epoxy resin, and initial curing and exothermic peak temperature of epoxy resin decreased owing to the addition of amino MWNT. However, apparent activated energy (Ea) of amino MWNT/epoxy resin composites increased compared with that of pure epoxy resin, because the cross-linking reaction between amino MWNT and epoxy resin inhibited the movement of epoxy resin molecule. |
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