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Grafting of ethylene glycol methacrylate phosphate (EGMP) monomer polymerized from alumina nanoparticles has been performed in order to confer a better thermal stability and fire retardancy to PMMA and PS nanocomposites. Grafting and polymerization processes have been investigated using FTIR, TGA, and elemental analyses. Thermal stability and decomposition routes of monomer and polymer grafted alumina have been studied using thermogravimetric analysis and compared with the thermal behavior of the same alumina modified with octylsilane. The thermal stability of EGMP supported by the nanoparticles is higher than that of free EGMP. The incorporation of 5 wt% of both surface treated alumina in PMMA and PS leads to an improvement of thermal stability in comparison with unfilled polymers as well as nanocomposites containing unmodified alumina. Furthermore, the grafting of organic compounds on alumina also allows the peak of heat release rate measured using a cone calorimeter to be significantly reduced for PMMA nanocomposites. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The influence of magnesium dihydroxide (MDH) nanoparticles on thermal degradation and fire behavior of poly(methyl methacrylate) (PMMA) has been investigated by thermogravimetric analysis (TGA), cone calorimeter, and pyrolysis-combustion flow calorimeter (PCFC) tests, respectively. MDH nanoparticles with either lamellar or fibrous shape have been synthesized via a sol-gel technique and characterized by transmission electron microscopy (TEM) and X-ray diffraction analysis. PMMA-MDH nanocomposites have been prepared by melt blending the recovered MDH nanoparticles within PMMA at different loadings (5, 10, and 20 wt% MDH). According to TGA results, the incorporation of lamellar or fibrous MDH nanoparticles into PMMA leads to a significant improvement in PMMA thermal stability, both under air and inert atmosphere. The results obtained by PCFC and cone calorimeter tests show an important decrease in the peak of heat release rate (pHRR) concomitant with charring during the combustion. Lamellar MDH nanoparticles were found to be more efficient than fibrous MDH nanoparticles. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Epoxy nanocomposites containing halloysite nanotubes (HNTs) were developed and their low-concentration thresholds for thermal stability and flame retardancy were compared with that of epoxy system containing expandable graphite (EG), as a reference with superior flame retardancy. The effects of HNTs and EG on the peak of Heat Release Rate (pHRR), Total Heat Release (THR), and Time-To-Ignition (TTI) of the prepared samples were subsequently discussed. At low loading level of 3 wt.%, HNTs appeared more effective, as signaled by an enhanced thermal stability compared to the EG-incorporated composite at an identical loading, because of hindered mobility of epoxy chains in a well-cured epoxy network. At higher loadings (6 and 9 wt.%), however, exfoliation of EG because of heat build-up in the system was dominantly hindered the crosslinking of epoxy it the presence of HNTs, which consequently deteriorated thermal stability of epoxy. This was featured by the formation of intumescent flake on the surface of the epoxy that played the role of a physical barrier, and assisted in reduction of the value of pHRR, while it doubled the TTI value. Different functions of HNTs and EG in regard with thermal stability and flame retardancy of epoxy/amine systems were discussed experimentally and mechanistically. [ABSTRACT FROM AUTHOR]