Molecular sorption and diffusion of organic solvents through maleated rubber/layered silicate nanocomposites

The aim of the study is to investigate barrier properties of a nanocomposite material against organic solvents. Molecular transport phenomena of three alcohols, namely methanol, ethanol and isopropanol, through a nitrile rubber-based nanocomposite, are carried out in temperatures ranging from 23 to 70°C. For each configuration, mass transfer kinetics are investigated for three different types of clay nanoparticles using mass uptake experiments. Maleated nanocomposites with enhanced dispersion morphology are also examined. Results show that all molecular transport parameters are generally susceptible to temperature variations. Sorption and diffusion coefficients noticeably increased as temperatures increased. Polymer/solvent interaction seems to be similarly affected. Molecular volume of the penetrant is observed to have an influence on molecule migration. Diffusion coefficients are likewise affected and decrease with the linear increase of molecular volume. The diffusion mechanism is slightly altered by this factor and the Fickian mode is maintained. When filling the rubbery matrix with layered silicates, sorption decreases at equilibrium. Its level drops even lower with the maleation of the nanocomposite. However, the diffusion coefficient exhibits a less systematic trend. Randomly filled nanocomposites appear to have higher diffusivity than neat rubber, but diffusion parameter considerably decreases after maleation, which emphasizes the nanoclay’s dispersion effect.