Jobish Johns

Novel Interpenetrating Polymer Networks Based on Natural Rubber/Poly(vinyl alcohol)

Fully interpenetrating polymer networks (IPN) based on natural rubber (NR) and poly(vinyl alcohol) (PVA) were prepared by using glutaraldehyde as the common cross-linking agent. The mechanical performance of this system has been studied in detail. Stress-stain behavior, tensile strength, elongation at break and youngs modulus was determined. Effects of weight fraction on the physical properties of NR/PVA IPNs were also studied along with the thermal degradation behavior using thermogravimetric analysis. A remarkable improvement was observed in the mechanical strength and the thermal stability of the blend by the formation of IPN. The activation energy of degradation was analyzed using the Horowitz-Metzger equation. The solvent resistance properties of these samples were investigated by the equilibrium swelling method using benzene as a solvent. The impact of weight fraction of PVA on the solvent transport of the system was also analyzed. A reduction in swelling was exhibited with the addition of PVA to natural rubber by the formation of IPN. The water absorbability of the blend decreases by the addition of glutaraldehyde.

Effect of processing parameters on the vulcanisation of natural rubber using glutaraldehyde

ABSTRACT The process ability of vulcanising natural rubber using glutaraldehyde at low temperature has been studied. The main objective of this work is to improve the properties and stability of natural rubber (NR) using glutaraldehyde as a curing agent. In this study, the vulcanised samples were prepared systematically and compared with sulphur cured natural rubber vulcanisates. The influence of mole ratio of ammonia and glutaraldehyde, and the processing parameters (i.e. curing time and temperature) was investigated. The cured NR based on glutaraldehyde exhibited better hardness and thermal properties than that of the NR cured from conventional sulphur system. The experimental results reveal that the properties of glutaraldehyde cured NR can be developed with the proper additives combination and conditions adopted in the preparation. This cured system is very interesting due to it can be used for high temperature industrial applications. Moreover, it eases of processing at low temperature and cost.

Solvent Transport Properties of Er/Ps Thermoplastic Elastomeric Blends

Novel thermoplastic elastomeric blends from Polystyrene (PS) and Exudated Resin (ER) of Ailanthus Malabaricum tree are prepared by solution casting technique. The applicability of the resulting materials to design and fabricate barrier rubber materials for the transport and storage of liquids and gases has been studied in terms of solvent resistivity. It is important to carry out the transport studies to eliminate diffusion of chemicals into such material products. The sorption and diffusion of benzene through blends of Polystyrene and Exudated Resin of different compositions are studied at 35°C, 55°C and 65°C. The effects of blend ratio on diffusion, sorption and permeation coefficients are determined. The sorption data is used to estimate the activation energies of diffusion and permeation parameters. An anomalous behavior is observed for most of the blend compositions. The blend with 60/40 PS/ER combination at 35°C and 65°C exhibited Fickian transport mechanism. Minimum solvent uptake is observed for the blend ratio 60/40 PS/ER. This blend ratio shows better compatibility between the phases among the series of the blends studied.

Mechanical Properties and Morphology of ER/PS Blends

Thermoplastic elastomeric blends of Polystyrene (PS) and Exudated Resin (ER) with different compositions have been prepared by solution casting method. The mechanical performance of this system has been studied in detail. Stress-stain behavior, tensile strength, elongation at break and young’s modulus was determined. The effect of blend ratio on the mechanical properties and surface hardness has been analyzed. By the addition of ER reduces the plasticity of polystyrene. The blend with 60/40 PS/ER combination exhibited comparatively better mechanical properties. 60/40 PS/ER blend ratio shows higher compatibility between the phases among the series of the blends studied. It is explained on the basis of the morphology of the blend. Various theoretical models such as series, Parallel and Halpin-Tsai have been used to fit the experimental mechanical data. Scanning Electron Microscopy was employed to analyze the surface morphology of the blend.