Dye structure-intercalated layered double hydroxide (d-LDH) was synthesized using a one-step method, and its intercalated behaviors have been characterized by Fourier transform infrared spectroscopy (FTIR), wide angle X-ray scattering (WAXS), scanning electron microscopy, thermogravimetric analysis (TGA), etc. As a novel functional potential fire-retarding nanofiller, it was used to prepare a polypropylene-grafted maleic anhydride (PP-g-MA)/d-LDH composite by refluxing the mixture of d-LDH and PP-g-MA in xylene, aiming to investigate its effect on the flammability of the PP-g-MA composite. The morphological properties, thermal stability, and flame retardant properties of the PP-g-MA/d-LDH composite were determined by FTIR, WAXS, transmission electron microscopy, TGA, and microscale combustion calorimetry. Compared with NO3-LDH (unmodified LDH) and LDH intercalated by sodium dodecylbenzenesulfonate (conventional organo-modified LDH), d-LDH can significantly decrease the heat release rate and the total heat release of the PP-g-MA composite, offering a new approach to imparting low flammability to LDH-based polymer composites.

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Nanocomposites derived from poly(lactic acid) (PLA) and organically modified montmorillonite (oMMT) have been cross-linked by high-energy electrons in the presence of triallyl cyanurate (TAC). The morphology of untreated and cross-linked PLA/MMT nanocomposites was characterized by wide-angle X-ray scattering (WAXS) and transmission electron microscopy (TEM). This treatment can improve both the thermal stability and the glass-transition temperatures of the PLA nanocomposites (e.g., PLA-MMT-TAC 30kGy, 50kGy, and 70kGy) because of the formation of cross-linking structures in the nanocomposites that will considerably reduce the mobility of polymers. Interestingly, at relatively low irradiation doses (e.g., 30 and 50 kGy) a good balance between tensile strength and elongation at break for the PLA nanocomposites could be achieved. These mechanical properties are superior to those of pure PLA. Therefore, combining nanotechnology and electron beam cross-linking is a promising new method of simultaneously improving the mechanical properties (toughness and tensile strength) and thermal stability of PLA.

By using resin transfer molding (RTM) technology, carbon fiber (CF) reinforced epoxy composites (CF/Epoxy, CF/PES/Epoxy, and CF/PES-MWCNT/Epoxy) are prepared. CF is the reinforced fiber, Epoxy is the epoxy matrix, and PES-MWCNT is the multiwall carbon nanotubes doped polyethersulfone film. Their fire behavior is systematically studied according to limiting oxygen index (LOI), vertical burning test (UL94), and cone calorimeter test (CCT). Their thermal degradation process, kinetics, and flame retardant mechanism are investigated from thermogravimetric analysis (TGA) and scanning electronic microscopy (SEM). The results show that these composites can reach the highest UL94 rating with the 5VA level achieved. Moreover, introduction of PES-MWCNT improves the LOI values, reduces the total smoke production (TSP), and slightly decreases peak of heat release rate (PHRR) and total heat release (THR). This improvement in the flame retardancy results from the increased degradation activation energy (E a) and formation of stable protective char layers in the combustion process, as indicated by the thermodegradation kinetic analysis and the SEM observation of the char residues’ microstructure, respectively.

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An effective approach relying on in situ direct polycondensation to synthesize polyamide grafted with functional carbon nanotube (PA-FCNT) has been reported and the properties of PA nanocomposites were studied in this paper. The oxidized carbon nanotube (CNT-COOH), which was modified by the treatment of CNTs with mixed concentrated sulfuric acid and nitric acid, were converted into aminofunctionalized CNTs (FCNT) by the reaction between CNT-COOH and an excess amount of 1,2diaminoethan. Then, the aromatic-aliphatic polyamide/FCNT nanocomposites (PA-FCNT) were synthesized by using in situ polycondensation. To prove the two types of grafted CNT (FCNT-sPA with the properties closer to CNT, and FCNT-lPA with the properties closer to the polymer), PA-FCNT had been separated simultaneously after in situ preparation of PA-FCNT nanocomposite. The grafting was confirmed by investigation of FCNT-sPA and FCNT-lPA structures by Fourier transform infrared spectra, thermogravimetric analysis (TGA), nuclear magnetic resonance and transmission electron microscopy and presence of FCNT and PA in both compounds were observed. The effect of FCNT and pristine CNT on the morphology, thermal stability and flammability of PA were studied by TEM, TGA and microscale combustion calorimeter (MCC). TGA analysis illustrated that the grafted FCNT significantly increased the thermal stability and slightly improved char residues of PA. MCC tests showed the incorporation of FCNT in the polyamide resulted in the significant reduction of the heat release rate and total heat release, indicating that the flammability of PA had been reduced greatly.