Publication: Effect of vulcanization system on properties of natural rubber vulcanizate in the presence of natural antioxidant
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Date
2012-06-01
Authors
Ishak, Nur Syuleha
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Abstract
Good sources of phenolic compound have been found in the oil palm extracted from the leaves which known to be good antioxidant. Therefore, this research is carried out on oil palm
leaves (Elaeis Guineensis species) extract to act as alternative component of synthetic antioxidant with the aims of producing more environmental friendly and nontoxic rubber
compounding process. This research objective is to investigate the effect of vulcanization system on properties of natural rubber vulcanizate in the presence of natural antioxidant
obtained from oil palm leaves (Elaeis guineensis) by comparing it with commercial antioxidant (TMQ) effect. The effectiveness of the antioxidant as ageing retardant is explored before and after thermal degradation process. Natural rubber vulcanizates were cured at 1600C with efficient (EV), semi-efficient (SEV) and conventional (CV) sulphur system. The amount of sulfur and accelerator was varied to change the network crosslink density of vulcanizates. Cure characteristic were studied using oscillating disc rheometer to obtained scorch time, cure time, minimum torque and maximum torque. The tensile, tear and swelling were tested before and after ageing for 4, 7, and 14 days at 70 oC. Thermal aging was performed on natural rubber vulcanizates to assess the thermal degradation behaviour of the rubber network. The effect of thermal degradation was measured from the changes in the retention of the vulcanizates as functions of time at constant temperature. The observed mutual activity has been discussed based on the mechanical properties and crosslink density. From the research and study, the result obtained show that Natural antioxidant (NA) has the best and comparable result with TMQ antioxidant in Semi efficient vulcanization system (SEV). SEV/NA compound before aging posses higher tensile strength, elongation at break, cure time but nearly the same value of M100, M300 and tear strength compared to unaged SEV/TMQ compound. The crosslink density of SEV/NA also lowers than SEV/TMQ. Naturally, EV system has the lowest mechanical properties compared to CV and SEV system due to its lowest degree of crosslinking. EV/NA actually followed SEV trend of result which somehow comparable with EV/TMQ but at lower value due to it’s predominantly contain monosulphide network. However, CV system show different trend of result where CV/NA show lower value of cure time, crosslink density, tensile strength, elongation at break , M100, M300 but higher tear strength compared to CV/TMQ compound.