Study of hexafunctional polyol in high solids air-drying alkyd: Improved film performance

A series of high solid alkyd polymers from soya oil fatty acid (SOFA) and dehydrated castor oil fatty acid (DCOFA) combinations with varying percentage of dipentaerythritol (DPE, a hexafunctional polyol) have been synthesized and characterized for their physicochemical, optical, thermal and mechanical properties. For the study purpose the polymers were prepared at 80% solids in mineral turpentine oil (MTO) keeping the oil length constant. The curing behavior of the alkyds was studied using FT-IR and DSC. Increasing DPE content in resin backbone was found to increase gloss and hardness. The gloss improvement was also supported well by atomic force microscopy (AFM) pictures. Results of 500 h of QUV exposure revealed higher gloss retention for DPE-based systems. When compared for the anticorrosive properties, the EIS spectrum reveals that alkyd film containing 100% DPE has the higher value of impedance.