Assessment of Physico-mechanical Properties of Natural Rubber and Modified Natural Rubber Vulcanizates with Watermelon Rind as Fillers

Natural Rubber (NR) has a relatively low tensile modulus and strength, hence the need for reinforcing fillers to increase its tensile strength, hardness and abrasion resistance. In this study, NR was deproteinized, epoxidized and depolymerized. The functional groups of the NR and the modified NR were determined using Fourier Transform Infrared (FT-IR) spectroscopy. Watermelon Rind (WR) was used as fillers to replace Carbon Black (CB) in the compounding process. The shells were collected, dried, milled and sieved to 75 µm mesh size. Powdered WR was carbonized at 250oC for 1.5 hrs to obtain Carbonized Watermelon Rind (CWR). The Uncarbonized Watermelon Rind (UWR) and CWR powder were characterized based on particle size, loss on ignition, volatile matter, moisture and ash content. The UWR and CWR were used to replace CB at 0, 50 and 100% for the NR and modified NR compounding. The physico-mechanical properties of the different vulcanizates were determined for the effect of modification on the NR. The FT-IR result of the NR samples showed the presence of O-H, C-H, C=C stretching with C=H wagging bands used as the fingerprint region of NR. The results of the physico-mechanical properties revealed that an increase in shell content in the NR decreased its tensile strength and elongation but improved the physico-mechanical properties of the modified NR. This study showed that watermelon rind can be a viable alternative source of carbon filler for improved physico-mechanical properties of modified natural rubber.