This article presents a brief but concise review of the current research efforts on polymeric nanocomposite foams production, characterization, and applications. Survey indicates that the emergence of nanocomposites has resulted in the development of a new group of materials regarded as nanocomposite foams. Nanocomposites result from the use of nano-sized (10-09 m) particles as fillers to modify and enhance the properties of polymers and other matrices. The combination of functional nanoparticles and foaming technologies such as supercritical fluid foaming, chemical foaming, syntactic foaming, aerogel foaming, phase inversion foaming etc. generate these new materials regarded as nanocomposite foams that have light weight, high specific strength, and multifunctional attributes. Enhanced thermo-mechanical properties of nanocomposite foams result from improved cell morphology that is mainly attributable to the role of nanoparticles as nucleation agents for bubble generation. High-specific mechanical properties and multifunctional characteristics of nanocomposite foams make them cost-effective and desirable in a multitude of application areas including structural, energy-dissipating/absorbing, acoustical insulation, flammability resistance, and others. Of particular importance in this study of nanocomposite foams is the flammability resistance effect of nanoparticles. The intumescent model (NIST, NMAB, and others) indicates that the flame barrier mechanism involves a high-performance carbonaceous-silicate char; this char build-up insulates the underlying material. Understanding this char build-up mechanism presents a challenge and area of research interest in the effort to develop new generation foams that are suitable in energy absorbing materials and structures.

Polyamide (nylon) 11 (PA11) were melt-blended by dispersing low concentrations of nanoparticles (NPs), namely nanoclays (NCs) and carbon nanofibers (CNFs) via twin-screw extrusion. To enhance their thermal and flame retardant (FR) properties, an intumescent FR additive was added to the mechanically superior NC and CNF PA11 formulations. For neat and NP-reinforced PA11 as well as for PA11 reinforced by both intumescent FR and select NPs (NC or CNF), decomposition temperatures by TGA, flammability properties by UL 94, and cone calorimetry values were measured. All PA11 polymer systems infused with both NPs and FR additive had higher decomposition temperatures than those infused with solely FR additive. For the PA11/FR/NC polymer blends, Exolit® OP 1312 (FR2) is the preferred FR additive to pass the UL 94 V-0 requirement with 20 wt%. For the PA11/FR/CNF formulations, all Exolit® OP 1311 (FR1), OP 1312 (FR2), and OP 1230 (FR3) FR additives passed the UL 94 V-0 requirement with 20 wt%.

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