Successful Initial Development of Styrene Substitutes and Suppressants for Vinyl Ester Resin Formulations

摘要

Recently, the U.S. Environmental Protection Agency (EPA) increased legislation to address hazardous emissions from composite manufacturing and repair by enacting new emission standards through the 'National Emission Standards for Hazardous Air Pollutants: Reinforced Plastic Composites Production,' which specifically targets styrene, methyl methacrylate, and methylene chloride as regulated hazardous air pollutants (HAP). Volatile organic compound (VOC) emissions are liberated during all phases of composite fabrication (Figure 1). Styrene emissions occur during the mixing of diluents, catalysts, and initiators into the system. Composite parts typically have very large surface-to-volume ratios, which allow up to 20% of the styrene content to be lost during the molding stage. During cure, elevated temperatures increase the vapor pressure of styrene and thus increase the rate of VOC emissions. Unfortunately, even alter cure during the lifetime of the part, styrene emissions can be substantial. Past work has shown that up to 50% of the styrene is unreacted after cure (1). Therefore, liberation of VOC emissions must be mitigated not only during composite processing, but also during curing and fielding of the composite part.