Bentonite clay/poly(vinyl alcohol) (PVA) inorganic/organic hybrid nanocomposite membranes were prepared via solvent casting method. A series of PVA nanocomposite membranes have been prepared by varying the concentration of the bentonite clay. Nanoscale dispersion of bentonite clay affected the properties of PVA. PVA with 5 wt % clay showed better enhancement in the properties. Both X-ray diffration and transmission electron microscopy showed uniform dispersion and exfoliated structure of the bentonite in the PVA membranes. The effective separation of azeotropic composition of isopropanol (IPA) and water mixtures was also carried out by using these membranes. The flux and separation factor of the membranes were increased with 1 wt % clay loading and followed by a decrease. The intrinsic properties of the membranes have been calculated using membrane permeance and selectivity. The 1 wt % clay loaded membrane showed enhanced membrane permeance with a water permeance of 6500 gpu and a selectivity value of 46. The effective membrane area for transport has been analyzed from atomic force microscopy analysis. Finally, it is important to mention that the minimum nanoscale filler loading gave rise to the maximum separation efficiency for the azeotropic composition of IPA and water mixtures.
Flexible and conductive nanocomposites with enhanced mechanical and dielectric properties have been fabricated from reduced graphene oxide (RGO) reinforced polychloroprene rubber (CR). Composites were prepared on a two-roll mixing mill and the morphological analysis using SEM and TEM showed good dispersibility and exfoliation of RGO layers in the matrix. It imparted a critical role in the enhancement of mechanical and electrical properties of the composites. Composites with 0.9 phr of RGO showed an enhancement in tensile strength, tensile modulus and electrical conductivity as 92%, 75%, and 103 % respectively more than the pristine polychloroprene. RGO formed a good conducting percolating network in the polychloroprene matrix and it led to the formation of a dielectric composite material with enhanced electrical properties.graphene oxide composites show superior mechanical, thermal, gas barrier, electrical, conductive and flame retardant properties compared to those of the neat polymer [15]. The improvement in mechanical and electrical properties of graphene based polymer composites is much better in comparison to that of clay or other carbon filler-based polymer composites [16]. Graphene oxide sheets are more compatible with organic polymers and as a result GO has a considerable attention as reinforcing filler in polymer composites. Like graphene, RGO is electrically
Natural fibres are a good reinforcing material. Among the various natural fibres, sisal fibre is of particular interest, since its composites have high impact strength besides having moderate tensile and flexural properties compared to other lignocellulosic fibres. Sisal fibre is a promising reinforcement for use in composites on account of its low cost, low density, high specific strength and modulus, no health hazards, easy availability in some countries and renewability. The present work focused on the recent developments in the field of sisal fibre reinforced phenol formaldehyde composites with reference to the properties of sisal fibre, processing techniques, and the physical and mechanical properties of the composites. The mechanical properties of the composites show much improvement by the addition of sisal fibre of optimum fibre length 40 mm and fibre loading 54 wt%. The better fibre matrix interaction is shown by sisal-PF containing 54 wt%. The comparison with other natural fibres shows that sisal fibre is a good reinforcing agent in PF matrix. Flexural strength and impact strength of the composites were examined and are increased with increasing the fibre content. Ageing studies of the composites showed a similar trend to that of un-aged samples. Interestingly, water absorption test results show that composite with 54 wt% fibre loading have good interaction with the matrix and contains less voids.
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