| Though some progress on fabricating carbon nanotubes (CNTs)/epoxy composites have been achieved during the past few years, several principle problems have not been got over by now. Those methods recently used to disperse CNTs in polymer matrix cannot disperse CNTs in polymer matrix absolutely uniformly. Consequently, exploring other effective dispersing method remains one of the key problems for fabricating high performance CNTs/polymer composites.In this study, the amino-functionalized multi-walled carbon nanotubes (MWNTs) were produced, and the effects of amino-functionalization on the dispersion of MWNTs in epoxy resin and the properties of the composites were studied.Different acid system and reaction conditions were used to treat MWNTs. The effect of these acid systems on the structure and the chemical nature of the MWNTs were studied. Results showed that by treating the MWNTs with a mixture of sulfuric acid and nitric acid, under relatively gentle reaction condition, could produce a great amount of carboxyl groups on the surface of MWNTs, while bringing no great damage to the MWNTs.By the acid-thionyl route used in this study, triethylene-tetramine (TETA) groups were grafted onto the surface of MWNTs successfully. Results showed that amino-functionalization could not only change the inert surface of MWNTs into active surface, but also enlarge the interspaces in the MWNTs network, which was found helpful to the dispersion of MWNTs in epoxy resin.The effect of amino-functionalized MWNTs on the curing behavior of epoxy/ triethanolamine (TTA) system was investigated using differential scanning calorimetry (DSC). Since the TETA grafted on the amino-functionalized MWNTs could act as curing agent and the produced tertiary amine could act as anionic catalysts for the curing reaction of epoxy/TTA system, the curing activation energy of the epoxy/TTA system was decreased by the addition of amino-functionalized MWNTs. The curing heat of epoxy/TTA/amino-functionalized MWNTs (weight ratio of 1/0.1/0.01) system was higher than epoxy/TTA (weight ratio of 1/0.1) system,while the curing heat of epoxy/TTA/unfunctionalized MWNTs (weight ratio of 1/0.1/0.01) was lower than epoxy/TTA (weight ratio of 1/0.1) system. The addition of the amino-functionalized MWNTs increased the curing degree of the epoxy matrix.MWNTs/epoxy resin composites were fabricated using ultra-sonication method. The effect of amino-functionalized MWNTs on the properties of the epoxy resin was studied. It was found that the amino-functionalized MWNTs were easier to be dispersed and could improve the strength, toughness, glass transition temperature and initial decomposing temperature of the epoxy resin.The effect of amino-functionalized MWNTs on the light transmittancy of epoxy was studied and compared with that of unfunctionalized MWNTs. The application possibility of amino-functionalized MWNTs/epoxy resin composites as packing materials for optoelectronic devices was also evaluated solely in term of light transmittance of the composites. Because amino-functionalization could improve the dispersion of MWNTs in epoxy resin, the amino-functionalized MWNTs/epoxy composites still hold a relative high light transmittancy even the refractive index difference between MWNTs and epoxy resin exceeding 0.1.Two types of MWNTs, with different structure and morphology, were used to fabricate epoxy matrix composites. Mechanical, thermal and TEM measurements were performed to evaluate the different influence of the structure and morphology of MWNTs on the mechanical and thermal properties of MWNTs/epoxy composites. Results showed that the different structure and morphology of MWNTs brought great difference to the mechanical and thermal properties of the obtained MWNTs/epoxy resin composites, and amino-functionalization was found helpful in improving the dispersion of the MWNTs in epoxy resin and thus in fabricating MWNTs/epoxy resin composites with improved mechanical and thermal properties.
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