Gas Barrier, Rheological and Mechanical Properties of Immiscible Natural Rubber/Acrylonitrile Butadiene Rubber/Organoclay (NR/NBR/Organoclay) Blend Nanocomposites.

In this paper, gas permeability studies were performed on materials based on natural rubber/acrylonitrile butadiene rubber blends and nanoclay incorporated blend systems. The properties of natural rubber (NR)/nitrile rubber (NBR)/nanoclay nanocomposites, with a particular focus on gas permeability, are presented. The measurements of the barrier properties were assessed using two different gases-O2 and CO2-by taking in account the blend composition, the filler loading and the nature of the gas molecules. The obtained data showed that the permeability of gas transport was strongly affected by: (i) the blend composition-it was observed that the increase in acrylonitrile butadiene rubber component considerably decreased the permeability; (ii) the nature of the gas-the permeation of CO2 was higher than O2; (iii) the nanoclay loading-it was found that the permeability decreased with the incorporation of nanoclay. The localization of nanoclay in the blend system also played a major role in determining the gas permeability. The permeability of the systems was correlated with blend morphology and dispersion of the nanoclay platelets in the polymer blend.

Transport characteristics of organic solvents through carbon nanotube filled styrene butadiene rubber nanocomposites: the influence of rubber-filler interaction, the degree of reinforcement and morphology.

The transport behaviour of some aromatic and aliphatic solvents through carbon nanotube filled styrene butadiene rubber composites has been investigated. The aim of the present work is to investigate the role of the sorption technique in analysing the compatibility and the reinforcing effect of MWCNTs as a filler in the SBR matrix. It also focuses on the investigation of the relationship between the dispersion of CNTs in the SBR matrix and its transport behaviour. The diffusion and transport of organic solvents through the membranes have been investigated in detail as a function of CNT content, nature of solvent and temperature in the range of 28-60 °C. Solvent uptake, diffusion, sorption and permeation constants were investigated and were found to decrease with the increase of CNT loading. Transport properties could be related to the morphology of the nanocomposites. At high concentration CNT particles form a local filler-filler network in the rubber matrix. As a result, the transport of solvent molecules through the polymer is hindered. The rubber-solvent interaction parameter, enthalpy and entropy of sorption have also been estimated from the transport data. The values of rubber-solvent interaction parameters obtained from the diffusion experiments have been used to calculate the molecular mass between the crosslinks of the network polymer. The better reinforcement at higher filler loading was confirmed from the cross-link density values. The extent of reinforcement was evaluated using Kraus and Cunneen and Russel equations. The Affine and Phantom models for chemical crosslinks were used to predict the mobility of the crosslinks. The Phantom model gave better fitting indicating that the chains can move freely through one another, i.e. the junction points fluctuate over time around their mean position without any hindrance from the neighbouring molecule. The diffusivity datas of the systems have shown dependence on the temperature and microstructure of the nanocomposite. Finally, the diffusion data have been compared with theoretical predictions.