Production of Alkyd Resin from Selected Drying / Non-Drying Oil Blend: Correlative Study of Physicochemical Properties and Modelling

Abstract

This study examines the production of alkyd resins from blends of drying oil (rubber seed oil, RSO) and chemically modified non-drying oil (palm kernel oil, PKO) to reduce after-yellowing associated with saturated lauric oils. Crude PKO, with an initial iodine value of 50.9 gI₂/100 g, was modified through epoxidation, hydroxylation, and hydration, achieving about 80% conversion of double bonds and reducing the iodine value to 15.8 gI₂/100 g. This modification improved colour stability and compatibility with RSO-rich alkyd systems. Oil blends (100% RSO, 100% modified PKO, 30:70, 50:50, and 70:30) were prepared, and their physicochemical properties were determined prior to polyesterification. Alkyd resins were synthesized via alcoholysis–polyesterification under controlled temperature and catalyst concentration, and the resulting resins were characterized for viscosity, acid value, iodine value, free fatty acid content, and colour. Higher RSO content increased iodine value and improved drying behaviour. Process modelling using Response Surface Methodology (RSM) was carried out for 30DPKO:70RSO and 50DPKO:50RSO blends to evaluate percent yield, drying index, and viscosity. Strong correlations between experimental and predicted results were obtained for the 30DPKO:70RSO blend, while moderate to strong correlations were observed for the 50DPKO:50RSO blend. Overall, the results confirm that desaturated PKO blended with RSO is suitable for alkyd resin production, yielding resins with improved drying performance, stability, and reduced after-yellowing.