Characterisation of Rubber Seed Oil-Based Alkyd Resin for Surface Coating Applications in Delta State

Alkyd resins derived from non-edible plant oils offer a renewable alternative to petroleum-based coating materials, aligning with growing emphasis on sustainable surface protection solutions. This study characterises alkyd resin synthesised from rubber seed oil extracted from Hevea brasiliensis cultivated in Delta State, South South Nigeria. Rubber seed oil was extracted by solvent extraction, and the oil characteristics including acid value, iodine value, saponification value, and viscosity were determined. Alkyd resin synthesis was performed using alcoholysis followed by polyesterification with phthalic anhydride and pentaerythritol at varying oil lengths of 40, 55, and 70 percent. Coating films were prepared and evaluated for drying time, gloss, adhesion, pencil hardness, flexibility, and chemical resistance. The 55 percent oil-length alkyd resin produced optimal drying time of 4.2 hours and pencil hardness of 3H, with gloss values of 85 gloss units at 60 degrees measurement angle. Adhesion testing using cross-cut tape method achieved grade 0 classification, indicating excellent substrate bonding. Chemical resistance tests against dilute acid, alkali, and salt spray confirmed adequate performance for general-purpose protective coatings. Flexibility assessment using a mandrel bend test showed no film cracking at 3 mm bend radius for medium oil-length formulations. The study concludes that rubber seed oil represents a viable raw material for alkyd resin production in South South Nigeria, with potential to support domestic paint manufacturing and reduce dependence on imported coating raw materials. Keywords: rubber seed oil, alkyd resin, surface coating, oil length, Delta State