Diffusion of water and artificial seawater through coir fiber reinforced natural rubber composites

The diffusion of water and artificial seawater through cross-linked coir fiber reinforced natural rubber composites was analyzed. The effect of fiber loading, chemical treatment, and bonding agent on liquid sorption was investigated. Based on the experiments, it is suggested that the probable mechanism of transport in gum compound is Fickian and that in composites is anomalous. The liquid uptake of all the composites is higher in water than that in artificial seawater. The composites showed increased swelling with fiber loading in water and artificial seawater. The influence of silica in the bonding system on swelling of the composites was also analyzed. In the case of gum compound, the desorption process is also Fickian, similar to the absorption of water and seawater. But the desorption of composites exhibited deviation from Fickian behavior. The effect of chemical treatment of coir fibers on the swelling was analyzed and found that the uptake of water and artificial seawater is reduced further in composites containing treated fibers. (c) 2005 Society of Plastics Engineers.