Cure, physico-mechanical and equilibrium swelling properties of groundnut shell-filled natural rubber

E. Osabohien*, B. E. Okoh and S. H. O. Egboh

Department of Chemistry, Delta State University, Abraka (Nigeria)

ABSTRACT: The cure characteristics, physico–mechanical and equilibrium swelling properties of natural rubber vulcanizates filled with groundnut shell (GNS) and commercial grade carbon black, CB (N330) were investigated. The results showed that the scorch and cure times decreased while the maximum torque (Tmax) increased with increasing filler content for both filled vulcanizates. The tensile strength of both GNS and CB (N330) – filled vulcanizates increased to a maximum at 30phr and 40phr filler content respectively before decreasing with increasing filler loading. Properties such as elongation at break and rebound resilience decreased while modulus, specific gravity, hardness and abrasion resistance increased with increasing filler loading for both filled vulcanizates. However, the locally sourced filler, GNS, imparted lower specific gravity and strength (reinforcement) compared with CB (N330) filler. The equilibrium swelling in kerosene, diesel and toluene of the natural rubber vulcanizates decreased steadily with increasing filler loading, although the percentage equilibrium swelling of carbon black (N330)-filled vulcanizates were less than that of groundnut shell-filled vulcanizates probably due to less moisture content and finer particles of the CB(N330) filler.

KEYWORDS: Natural rubber; groundnut shell; fillers; reinforcement; swelling

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