Acrylics: A Literature Review of Thermal Decomposition Products and Toxicity

Abstract

A comprehensive literature review on the thermal decomposition products and combustion toxicity of acrylics is presented. The types of products produced by the thermal decomposition of acrylic polymers vary widely. At lower temperatures, simple methacrylate polymers are degraded almost entirely to monomer, whereas simple acrylate polymers are degraded primarily to chain fragments and the alcohols corresponding to the ester groups. More complex methacrylate and acrylate polymers appear to be degraded primarily to the olefins corresponding to the ester groups. The major products formed through the thermal decomposition of polyacrylonitrile include HCN, NH3, CO, CO2, and various nitrile compounds. The decomposition of acrylonitrile copolymers (e.g., acrylic and modacrylic fibers) can result in the release of additional compounds. In general, modacrylic combustion products appear to be more acutely toxic than those of other acrylic materials tested or wood. Modacrylic produced a shorter time to incapacitation and time to death than poly(methyl methacrylate) in the FAA test, and, in the NBS test, the LC50 was more than fivefold lower than that for polyacrylonitrile. In addition, the LC50 of modacrylic in the University of Pittsburgh test was an order of magnitude lower than that for the standard test material, Douglas fir.