Physical and Mechanical Properties of Starch/Natural Rubber Biopolymer Blends

The effects of starch fillers on the physical and mechanical properties of starch/natural rubber blends were investigated with reference to carbon black filled natural rubber. Starch was extracted from three plant crops namely, amora, potato and yam and applied as fillers in natural rubber formulations. Starch/natural rubber (NR) blends were prepared by directly mixing and co-coagulating rubber latex and gelatinized starch by a coagulating agent via latex compounding method. There was improvement in tensile strength and elongation at break especially at 30 phr filler loading for all the starch/natural rubber blends in comparison with the carbon black filled natural rubber. Although the carbon black filled natural rubber at 30 phr gave the highest tensile strength (87.6 Mpa), it however produced a moderately low elongation at break of 6807 compared with amora starch filled NR (10007), potato starch filled NR (6654) and yam starch filled NR (12440) respectively. Carbon black filled natural rubber produced the highest value in hardness (66-68) compared with the starch filled rubber samples at 30 phr filler loading. It was further observed that filler loading restricted swelling in toluene solvent probably as a result of filler – rubber interaction and adhesion and this phenomenon increased with filler loading from 10 phr to 30 phr in the starch/natural rubber blend and also in the reference sample. However filler loading from 10 phr to 30 phr in all the samples increased the degree of crosslink density (Vc mol cm-3).