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ABSTRACT

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In this research, the comparative studies on solubility and thermodynamics properties of natural rubber vulcanizates filled with blends of activated palm kernel shell and carbonized palm kernel shell has been investigated. Palm Kernel Shell (PKS) was locally sourced. washed and sun dried to remove accompanying and moisture. The PKS was then pulverized to particle size, carbonized at 600°C for one hour (1hr) using Carbolite furnaces and chemically activated using 0.1M H 3 PO 4 and 0.1M KOH solutions. The NR-filler loading concentrations of CB/APKS and CB/CPKS were compounded using two-roll mill. The solubility was done using three different solvents of water, kerosene and petrol respectively. The solubility results obtained for CB/APKS and CB/CPKS has no significance difference as the temperature varies when immersed in water. The solubility values observed for CB/APKS and CB/CPKS ranges from 1.06g to 1.19g and 1.03g to 1.19g across the samples respectively. This shows that since the filler is an organic substance, it has little or no affinity for water. In the case of kerosene and petrol, both are organics and the filler is an organic substance which follows the statement 'likedissolves-like' as the temperature increases, the absorption of kerosene is lower than that of petrol. The results recorded for kerosene across the samples of CB/APKS and CB/CPKS ranges from 1.18g to 4.37g and 2.02g to 4.79g while the results for petrol ranges from 2.25g to 4.92g and 2.51g to 4.88g respectively. This may be due to the fact that petrol is volatile and flammable compared to kerosene. The results of the activation energy were a reflection of the solvent's permeability except for water which showed contrary results. The results of the activation energy obtained for the three solvents across CB/APKS and CB/CPKS were 5.55 KJ/mol for water, kerosene with 9.48 KJ/mol and petrol with 13.61 KJ/mol respectively. The results observed for water might be due to its nature as the universal solvent being entirely different from other solvents in terms of reactivity and anomalous property. This means polar solvents dissolve polar molecules while nonpolar solvents dissolve nonpolar molecules. This research shows that both CB/APKS and CB/CPKS possess great potential in rubber system.

An investigation into how different mixing schemes infl uences the physicomechanical properties, aging, sorption, diffusion and permeability of ketones (acetone and cyclohexanone) through vulcanizates from blends of natural rubber (NR) and low molecular weight natural rubber (LMWNR) was reported. The compounding ingredients were mixed with the NR (base polymer) and LMWNR (base polymer) using three different mixing schemes by adopting the semi-effi cient sulphur vulcanization compounding formulation. In scheme 1, the natural rubber and LMWNR were fi rst mixed before adding the compounding ingredients. In scheme 2, the compounding ingredients were fi rst mixed with the NR before adding the LWMNR and in scheme 3; the compounding ingredients were fi rst mixed with the LMWNR before adding the NR. The physico-mechanical results of the vulcanizates showed that changes in the mixing schemes signifi cantly infl uence the tensile properties of the vulcanizates. The tensile strengths of the vulcanizates prepared with mixing scheme 2 were 3.5 MPa lower than vulcanizates from scheme 1, while scheme 3 was lower than scheme 1 with 7.8 MPa. The aging result of the vulcanizates from all the mixing schemes were found impressing. The activation energy and free energy change were highest with scheme 1 while the extent of acetone and cyclohexanone penetrations were at lowest with scheme 1, signifying a well crosslinked and ketone resistant vulcanizates.