New developments in flame retardancy of styrene thermoplastics and foams

Abstract

This review provides an insight into new developments in flame retardancy of the broad class of styrenic polymers but mostly focuses on commercially important styrene thermoplastics, on some blends based on polystyrene as well as on polystyrene foams. Although halogen‐based systems continue to dominate in flame retardancy of styrenic polymers, various alternative systems are being developed. Especially, activity is observed with phosphorus‐based flame retardants, where some systems are already commercially available. There is also significant activity with nanocomposites, where good results in retarding flame spread have been achieved, but the problem of ignition resistance has not been solved yet. Critical discussion of various flame‐retardant systems developed for styrenics is given. Copyright © 2007 Society of Chemical Industry

Extrusion Foaming of Poly(styrene‐co‐acrylonitrile)/Clay Nanocomposites Using Supercritical CO2

“…[13] Nowadays, the research focuses on halogen-free flame retardants due to environmental and health concerns. [14][15] In that context, nanoclays are attracting an increasing interest due to their well-known flame retardant effect at very low level (3-5 wt.-%). [16][17][18] In opposition with usual flame retardants, nanoclays may also mechanically reinforce foams, thus enhancing both properties at once, which is unique.…”

Swelling of organoclays in styrene. Effect on flammability in polystyrene nanocomposites

“…This greater thermal stability stems from the chemical and physical action of the crystalline layers of the silicate dispersed in the matrix that inhibited the diffusion of the decomposed product in the polymer matrix. Thermal decomposition of the organically modified montmorillonites starts at around 200°C and proceeds according to the Hofmann degradation mechanism [19]. The decomposition products are combustibles that feed the combustion in the flame.…”

“…The suggested mechanism by which clay nanocomposites reduce the heat release rate involves the formation of a char that serves as a barrier to both mass and energy transport [10]. According to Levchik and Weil [19] flame retardancy achieved with nanocomposites alone is not enough for the ignition resistance inferred by the UL-94 test and they suggest a better approach to combine the nanocomposite with another flame retardant, such that the nanocomposite provides the base reduction in flammability, and the secondary flame retardant provides the ignition resistance. Several papers [20][21][22] investigated the effect of the chemical and physical structure of polymer/clay interfaces on the flammability of polymer composites and nanocomposites.…”

Chemical Composition of Nanoparticles Released from Thermal Cutting of Polystyrene Foams and the Associated Isomerization of Hexabromocyclododecane (HBCD) Diastereomers

“…Polystyrene foam is used in numerous applications including building insulation materials, packing materials, and architectural models (Wünsch, 2000;Levchik and Weil, 2008) with the well-known advantages such as low cost, light weight, resistance to moisture and heat transfer. The annual global production exceeded 10 7 tons per year in 2000 and the number has been increasing since then.…”