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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. [ABSTRACT FROM AUTHOR]

The present study focuses on the influence of layered silicate nanoparticles on barrier properties of a rubber/nanoclay nanocomposite (RCN). Most of the previous works deal with the importance of the surface chemistry of the nanoclay on the performance of the material. In this paper were rather investigated the effect of the processing conditions. Elastomer nanocomposites based on nitrile butadiene rubber and layered silicate nanoparticles were prepared using three different techniques: chemical dissolution, mixing in an internal mixer and melt-mixing with a twin-screw extruder. Chemical resistance to methanol was assessed using gravimetric method and mass transfer kinetic parameters were then deduced. Mass uptake results clearly showed that extruded RCN exhibited the highest chemical resistance. Barrier properties were subsequently correlated to the morphological structure of the rubber/nanoclay system. Small-angle X-ray diffraction patterns indicated that this improvement was due to a preferred alignment of the nanoparticle in the structure. Further, inspection revealed an anisotropic orientation profile of the nanoclay layers over the thickness of a sheet-like extruded material. In addition, a neat decrease of chemical sorption was spotted with mixing and chemically processed RCN materials over the unfilled rubber. The state of dispersion of clay nanoparticles was also probed in these nanocomposites using X-ray diffraction. The findings suggested an intercalation during processing. Further, transmission electron microscopy observations were suggesting a bimodal state of dispersion over spotting individual nClay platelets along with the layered stacks. Improvement of mass transport kinetic parameters was recorded over increasing the shear stress as well as the residence time when RCN were prepared in the internal mixer. [ABSTRACT FROM AUTHOR]