Thermal stability/stabilization carbon-based nanocomposites

Acid modified multi-walled carbon nanotubes and Mesua ferrea L. seed oil-based hyperbranched polyurethane-based nanocomposites have also been reported, exhibiting 300% improvement in tensile strength, enhancement of thermal stability up to 275°C, excellent shape recovery up to 98% (Fig. 11.7), enhanced biodegradabUity and cytocompatibility, confirmed by the inhibition of a RBC haemolysis test at a very low loading of CNT. ... 

Sanchez studied the functionalization of oxidized SWCNTs and MWCNTs dispersed in thermoplastic elastomers based on poly(butylene terephthalate) (PBT)/ poly(tetramethylene oxide) (PTMO). These nanocomposites showed good dispersion and enhancement in thermo-oxidative stability [27]. 1 % of pristine multi-walled carbon nanotube (MWCNTs) were dispersed in silicon rubber. The SR nanocomposites showed 28 % better thermal stability and 100 % improvement in the ultimate tensile strength is achieved as compared with the pristine polymer matrix counterpart [28]. Also ionic liquids have been tested to improve the dispersion and thermal stability of MWCNTs in polychloroprene rubber (CR) showing improvement in these properties [29]. On the other hand the effect of carbon nanofiber on nitrile rubber was studied. It has been found that the nanofiber increase the thermal stability and decrease the flammability [4]. 

Songmin et al. reported the preparation of chitosan hydrochloric acid salt and the effect in improving the dispersion of carbon nanotubes in different solvents and silicone rubber. It was also found that treated carbon nanotubes could be dispersed in the silicone rubber homogeneously based on SEM and XRD analysis. The incorporation of carbon nanotubes enhanced the thermal stability of the silicone rubber. They also significantly improved the mechanical properties of the silicone rubber matrix. From the FTIR spectra, it was befieved that chitosan hydrochloric acid salt adsorbed on the surface of the carbon nanotube and then interacted with silicone rubber matrix, resulting in the enhancement of dispersion of carbon nanotubes, improving thermal and mechanical properties in the resulting nanocomposites [124]. 

Similarly, Saeed and Park [65] synthesized PA 6-multiwaIl carbon nanotubes (MWNTs) nanocomposites via the in-situ polymerization technique, using pristine and COOH-functionalized MWNTs. Based on SEM morphology analysis, it was shown that the COOH-functionalized MWNTs were better dispersed in the PA 6 matrix than the pristine ones, owing to the covalent attachment of PA 6 molecular chains to the side walls of MWNTs, which could act as in-situ compatibilizers in the nanocomposites and enhance the dispersion of MWNTs. In terms of physical properties, the crystallization of nanocomposites was increased compared to that of virgin PA 6, due to the nucleation effect of MWNTs, while the thermal stability under nitrogen of the nanocomposites was superior. Turning to the mechanical properties of the nanocomposites, the uniformly dispersed MWNTs improved the tensile properties because of the reinforcement effect. 

Thermotropic LC polyester nanocomposites based on a small quantity of multi-walled carbon nanotubes (M WCNTs) can be prepared by in situ polymerization of l,4-bis(4-hydroxybenzoyloxy) butane and terephthaloyl dichloride. Significant change in the crystal structure of LC polyester cannot be observed even after forming the nanocomposite. The evidence from various instrumentation results indicates interaction of MWCNT with the surrounding liquid crystal molecules, most likely through aromatic interactions (H-stacking), The thermal stability and transition temperature of the hybrid is always better than pure LC polyester [71]. 

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