A method for measuring internal diffusion and equilibrium partition coefficients of volatile organic compounds for building materials

An experimental method for the determination of the internal diffusion coefficient (D) and partition coefficient (k_e) of volatile organic compounds (VOCs) is developed for dry building materials (such as carpet, vinyl flooring, plywood, etc.). The method is used to determine D and k_e for four VOCs (toluene, nonane, decane, and undecane ) through the backing material of a carpet specimen, for four VOCs (ethylbenzene, nonane, decane, and undecane) through a floor tile specimen, and three VOCs (cyclohexene, ethylbenzene, and decane) through a plywood specimen. It was found that the values of diffusion coefficients for a given material are inversely proportional to the molecular weights of the VOCs, whereas the value of the partition coefficients are proportional to the vapour pressures of the VOCs. The measured diffusion and partition coefficients are useful for predicting the emission rates of VOCs from building materials.