Natural rubber/organoclay nanocomposites: Effect of filler dosage on the physicomechanical properties of vulcanizates

Natural rubber/organoclay nanocomposites of varying filler loading [2 to 10 per hundred rubber (phr)] using derivative of tea (Camellia sinensis) seed oil were prepared by melt intercalation. Effects of filler dosage on the physicomechanical properties of the natural rubber (NR) vulcanizates were examined. Results of the mechanical properties indicates that tensile strength and tear properties of the modified organoclay/NR nanocomposites increases with increasing filler loading compared with the unmodified filled NR vulcanizates. Furthermore, rheological measurement showed that modified filled NR vulcanizate exhibited higher storage modulus (GI) than the unmodified filled NR. The values of the weight-swelling ratio (Qt) of the modified filled nanocomposites decreased remarkably and are lower than the unmodified filled NR vulcanizate. The higher value of the chemical crosslink density of 0.629 at 6 phr for the organoclay/NR composite indicate better reinforcement of the filler-rubber matrix over the unmodified. The scanning electron microscopy revealed that incorporation of modified organoclay up to 6 phr has transformed the failure mechanism of the resulting NR vulcanizate compared to the unmodified. There is an indication that the optimum level of incorporation of sodium salt of tea seed oil is 6 phr.   Key words: Vulcanizate, physicomechanical, nanocomposite, Camellia sinensis, natural rubber, organoclay.