Chemical Modification Of CNTs And PVA/CNTs Composites

Carbon nanotubes(CNTs) were modified by free radical addition and esterification. The modified CNTs were composited with poly(vinyl alcohol)(PVA), and the properties of obtained composites were studied. The dissertation contains two parts.In the first part, free radicals were generated by benzoyl peroxide and aromatic tertiary amine (N, N-dimethylaniline and N, N-bis (2-hydroxyethyl)-p-toluidine) decomposition. Multi-walled (MWNTs) and single-walled (SWNTs) carbon nanotubes were modified by small molecular radical addition or in situ polymerization. The Raman and IR spectroscopy results prove the covalent bonds on the surface of CNTs. TGA result shows the attaching group on the surface of SWNTs can attain8.26%. TEM shows that there is a layer of polymer covered on the surface of hydrolyzed poly(styrene-co-maleic anhydride)(HSMA) grafted CNTs, and the HSMA grafted CNTs can be relatively stable dispersed in water (pH=9).In the second part, HSMA was grafted to MWNTs by in situ polymerization initiated by azobisisobutyronitrile. Then poly (vinyl alcohol)(PVA) was reacted with the carboxyl on MWNT-HSMA. IR spectroscopy shows the covalent attachment of HSMA and PVA. The obtained two kinds of CNTs can stable disperse in water, and the MWNT-HSMA-PVA can stable disperse in dimethyl sulfoxide. PVA/CNTs composites films with different kinds of CNTs were produced by solution blending. High content PVA/MWNT-HSMA films have excellent electrical conductivity. When the content of CNTs was50wt%, volume resistivity of the composites can reduce to0.19(?)/cm. SEM of the tensile cross sections shows that the modified MWNTs have good dispersion in PVA matrix when in low content. The tensile modulus and tensile yield strength of the composites evidently increased, and MWNT-HSMA-PVA was more efficient in reinforcement than MWNT-HSMA.