Filler polyhedral silsesquioxane

The combinations of nanocomposite formation with a variety of conventional fire retardants, including halogen, phosphorus, mineral fillers, and other systems, have been examined and are reported in other places in this book. We feel that this combination approach must continue and will involve other nano-dimensional materials, including other clays, snch as the layered double hydroxides, polyhedral silsesquioxanes (POSSs), carbon nanotnbes and spherical nanoparticles, and other putative flame retardants. 

Bourbigot, S., Le Bras, M., Flambard, X., Rochery, M., Devaux, E., and Lichtenhan, J. 2005. Polyhedral oligomeric silsesquioxanes Application to flame retardant textiles. Fire Retardancy of Polymers New Applications of Mineral Fillers, Le Bras, M., Bourbigot, S., Duquesne, S., Jama, C., and Wilkie, C.A. (Eds.), Royal Society of Chemistry (Pub), U.K., pp. 189-201. 

Broadband dielectric spectroscopy is a powerful tool to investigate polymeric systems (see [38]) including polymer-based nanocomposites with different nanofillers like silica [39], polyhedral oligomeric silsesquioxane (POSS) [40-42], and layered silica systems [43-47] just to mention a few. Recently, this method was applied to study the behavior of nanocomposites based on polyethylene and Al-Mg LDH (AlMg-LDH) [48]. The properties of nanocomposites are related to the small size of the filler and its dispersion on the nanometer scale. Besides this, the interfacial area between the nanoparticles and the matrix is crucial for the properties of nanocomposites. Because of the high surface-to-volume ratio of the nanoparticles, the volume fraction of the interfacial area is high. For polyolefin systems, this interfacial area might be accessible by dielectric spectroscopy because polyolefins are nonpolar and, therefore, the polymeric matrix is dielectrically invisible [48]. 

New generadon nano scale fillers are challenging the domination of traditional fillers such a as carbon blacks and silica in the rubbery industry. Nanoscaled fillers such as layered sihcates, carbon nanotubes, carbon nanofibers (CNFs), exfoliated graphite, spherical particles and Polyhedral oligomeric silsesquioxane (POSS), etc., dispersed as a reinforcing phase in a mbber matrix are emerging as a relatively new form of usefiil material. 

Pan, G. Mark, J. E. Schaefer, D. W., Synthesis and Characterization of Fillers of Controlled Structure Based on Polyhedral Oligomeric Silsesquioxane Cages, and Their Use in Reinforcing Siloxane Elastomers. J. Polym. Sei., Polym. Phys. Ed. 2003,41,3314-3323. 

In summary, when surfactants are selected for nanofillers intended for PET nanocomposites, there are important requirements that should be met, substantially limiting the range of appropriate surfactants. As a first approach, alkylammoniums should be avoided, whereas alkylimidazoliums should be preferred. This last class of surfactants are applicable to high-performance nanocomposites beyond PET for example, they were successfully used in polystyrene and polyamide matrices [32], epoxies [35], and ABS polymers [36, 37], as well as for fillers other than clays, such as polyhedral oligomeric silsesquioxane (POSS) [38] and carbon nanoffibes [39]. 

Pan G, Mark JE, Schaefer DW (2003) Synthesis and characterization of fillers of controlled structure based on polyhedral oligomeric silsesquioxane cages and their use in reinforcing siloxane elastomers. J Polym Sci B Polym Phys 41(24) 3314—3323... 

Other molecular fillers include the fullerenes such as Cgg, and their derivatives. Like polyhedral ohgomeric silsesquioxanes, however, their commercial apphcation is severely limited by high cost. 

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