Mathematical model for characterizing the full process of volatile organic compound emissions from paint film coating on porous substrates

Volatile organic compound (VOC) emissions from coating materials, such as paint, can result in poor indoor air quality (IAQ). In this study, a fundamental mathematical model for VOC emissions from paint film was established based on the mass transfer mechanism. In this model, mass transfers in the air, at the air-paint interface, in the paint film, at the paint-substrate interface, and in the porous substrate are mathematically described. Three statuses of the paint film including wet, semi-dry, and dry were defined quantitatively by the saturation of VOC liquid in the pores of the paint film. Therefore, the entire process from the wet to dry stages of VOC emission from the material can be characterized by the new model. In addition, the model was validated using experimental data in the literatures. A case study revealed that the effects of indoor environmental parameters on VOC emission of paint film change with the stages of the paint film. The film thickness and the porosity of the substrate have more significant effects on the emission of the paint film in the semi-dry and dry stages, respectively. This analysis can provide environmental control strategies and material selection schemes for promoting good IAQ.