Effects of Surfactants on the Thermal and Fire Properties of Poly(Methyl Methacrylate)/Clay Nanocomposites

Nanocomposites of poly(methyl methacrylate) (PMMA) with layered silicates and with polyhedral oligosilsesquioxanes (POSS) were prepared by bulk polymerization. The thermal and fire stabilities of the various organically-modified clay and POSS nanocomposites were evaluated using both thermogravimetric analysis (TGA) and cone calorimetry. Thermogravimetric analysis is not a good criteria for evaluating nanocomposite formation but cone calorimetry can be. For montmorillonite systems, when more than 4% clay is present, the expected reduction in peak heat release rate is observed. For hectorite, a minimum of 6% clay concentration is required to achieve the same reduction in peak heat release rate. POSS has the potential to reduce the peak heat release rate but one must be careful in selecting the POSS material to be evaluated

Synergy Between Nanocomposite Formation and Low Levels of Bromine on Fire Retardancy in Polystyrenes

An organically-modified clay has been prepared using ammonium salts which contain an oligomeric material consisting of vinylbenzyl chloride, styrene and dibromostyrene. The presence of dibromostyrene enhances the flame retardancy of polystyrene nanocomposites compared to both the virgin polymer and polystyrene nanocomposites prepared from non-halogen-containing organically-modified clays. The nanocomposites were prepared both by bulk polymerization and melt blending and they were evaluated by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and cone calorimetry measurements. Bulk polymerization produced nanocomposites with reduced peak heat release rate, reduced total heat release and improved thermal stability. It is noteworthy that all these improvements were obtained with clay loading as low as 3% and bromine content less than 4%

Fire Retardancy of Vinyl Ester Nanocomposites: Synergy with Phosphorus-Based Fire Retardants

Vinyl ester (PVE) nanocomposites were prepared using both clay and polyhedral oligosilsesquioxanes (POSS) as the nano-dimensional material. From cone calorimetric data, it was shown that both POSS and clay affect the flammability of the nanocomposites to the same extent. To improve on the flame retardancy, the nanocomposites were combined with phosphorous-containing fire retardants (FRs) and the result compared to the benchmark halogen-containing system. The use of the cone calorimeter to investigate the fire properties of these nanocomposites showed a great reduction in peak heat release rate (PHRR) in the presence of phosphate and slight improvements in average mass loss rate (AMLR) while thermogravimetric analysis showed improvement in char yield in the presence of phosphate. Several different organically modified clays were used and they affected the flammability to different extents. The time that the resin and clay were mixed and the atmosphere in which the reaction was carried out do not have an effect on the flammability and thermal stability of the nanocomposites. The effect of curing temperature on the clay dispersion and flammability was also investigated

Synthesis, characterization and spectroscopic studies of some boron-containing hydrogen storage materials.

Synthesis, characterization and spectroscopic studies of some boron-containing hydrogen storage materials