Replacement of traditional unsaturated acid by bio-based itaconic acid in the preparation of isophthalic acid-based unsaturated polyester resin

Unsaturated Polyesters Resins (UPR) are largely prepared using non-renewable resources. Today the need is to make use of bio-based raw materials to reduce the use of petroleum-based chemicals, which in turn contributes to sustainability. The objective of this research was to investigate the effect of use of bio-based monomer i.e. itaconic acid for the synthesis of Unsaturated Polyester Resin (UPR) as replacement to traditional material like maleic anhydride. The synthesis of partial bio-based UPR involves the reactions of itaconic acid and maleic anhydride at different molar concentrations with isophthalic acid and neopentyl glycol were carried out. The synthesized resin was further characterized by gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR). Also, curing parameters were studied. Further synthesized UPR was processed into sheets of 3.5 mm thickness and the thermal and mechanical behaviour were tested by using dynamic mechanical experiments and thermal analysis. Substitution of maleic anhydride by itaconic acid proved to be advantageous since it offers improved mechanical properties with slight compromise of thermal properties.