Nanocomposite polymers, fire flammability properties

Morgan, A.B. Kashiwagi, T. Harris, R.H. Campbell, J.R. Shibayama, K. Iwasa, K. Gilman, J.W. Flammability properties of polymer-clay nanocomposites nylon-6 and polypropylene clay nanocomposites, in G.L. Nelson and C.A. Wilkie, Eds., Fire and Polymers Materials and Solutions for Hazard Prevention. ACS Symposium Series, Vol. 191. American Chemical Society, Washington, DC, 2001, pp. 9-23. 

In 1976 Unitika Ltd, Japan, first presented the potential flame retardant properties of polyamide 6 (PA6)/layered silicate nanocomposites. However, not until more recent studies did the serious evaluation of the flammability properties of these materials begin when Gilman et al. reported detailed investigations on flame retardant properties of PA6/layered silicate nanocomposite. From this pioneering work many attempts have been made to study the flammability properties of polymer/layered silicate nanocomposites. A wide range of polymers has been employed to provide either intercalated or exfoliated nanocomposites, which exhibit enhanced fire retardant properties. These include various thermoplastic and thermosetting polymers, such as polystyrene (PS), high impact polystyrene (HIPS), poly(styrene-co-acrylonitrile) (SAN), acrylonitrile-butadiene-styrene (ABS), polymethyl methacrilate (PMMA), " polypropylene 14,15,19-22 polyethylene is, 19,23-27 poly(ethylene-... 

The impact of the nanocomposite technology on polymers is huge, reflected in enhanced properties of the resulting PNs, such as enhanced mechanical, barrier, solvent-resistant, and ablation properties.12 The effect of nanocomposite technology on the thermal and fire performance of the polymers is primarily observed in two important parameters of the polymers (1) the onset temperature (7( ,nsct) in the thermogravimetric analysis (TGA) curve—representative of the thermal stability of the polymer, and (2) the peak heat release rate (peak HRR) in cone calorimetric analysis (CCA)—a reflection of the combustion behavior (the flammability) of the polymer. The Tonset will be increased and the peak HRR will be reduced for a variety of polymers when nanoscale dispersion of the nanoadditive is achieved in the polymer matrix. 

Although there has been extensive research (e.g., [1-9]) on the fire retardation effects of nanoclay on neat polymers, relatively few studies [15-31] have been conducted with polymer blend systems. In Table 8.1, the polymer blends as well as the tests conducted in [ 15-31 ] are presented. From this table, it is clear that the majority of these studies have been devoted to the morphology and thermal stability of polymer blend nanocomposites very few studies actually focused on their fire performance. Nonetheless, these studies [15-31] have generally led to the conclusion that the addition of nanoclay to polymer blends can result in remarkable improvement in (a) mechanical properties, (b) compatibilization, (c) viscosity, (d) thermal stability, and (e) flammability. 

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