Emission modeling of styrene from vinyl ester resin: Effect of styrene percentage, temperature, and resin depth

The use of vinyl ester (VE) resins in structural composite applications within the commercial and defense sectors has increased dramatically in the last decade. Styrene is a reactive monomer in VE resins, providing diluency to the resin system required in many liquid molding methods. Styrene is considered a volatile organic component (VOC), hazardous organic pollutant (HAP) and is currently under investigation for carcinogenic effects. The National Emission Standards for Hazardous Air Pollutants (NESHAP) program has enacted stringent Maximum Achievable Control Technology (MACT) standards which regulate the use and/or emission of styrene. A model to describe mechanisms of evaporation and diffusion from a styrene containing VE system was implemented based on an evaporation based diffusion model. In this study, the emission of styrene for various parameters including resin depth, test temperature, and styrene concentration have been investigated. It was observed that the emission rate and amount of styrene decreases with increasing resin depth, or decreasing exposed surface area for a particular period and resin system. It is also shown that diffusion coefficient and evaporation coefficient of styrene have an exponential relationship with temperature and styrene concentration. These efforts will lead to the development of a modeling tool capable of predicting the life-long emissions of VE based composite structures.