Correlations Between the Internal Diffusion and Equilibrium Partition Coefficients of Volatile Organic Compounds (VOCS) in Building Materials and the VOC Properties

In this study, a novel experimental method that was previously developed was used to directly measure the internal diffusion (D) and the equilibrium partition coefficients (k _e)for three classes of volatile organic compound (VOC), (1) aliphatic hydrocarbons, (2) aromatic hydrocarbons, and (3) aliphatic aldehydes, through typical dry building materials (plywood, particleboard, vinyl floor tile, gypsum board, subfloor tile, and OSB). For each chemical class, correlations between D and the VOC molecular weight and between k _e and the vapor pressure of VOCs were developed for every product. These correlations can be used to estimate D and k _e when direct measurement data are not available and, thus, facilitate the prediction of VOC emissions from the building materials using mass transfer theory. It was found that the values of diffusion coefficients for a given material are inversely proportional to the molecular weights of the VOCs, and the values of the partition coefficients are also inversely proportional to the vapor pressures of the VOCs. The measured diffusion and partition coefficients are useful for predicting the emission rates of VOCs from building materials.