Synthesis and Characterization of Novel Star-Shaped Itaconic Acid Based Thermosetting Resins

Abstract

A star-shaped thermoset resin was synthesized by direct condensation reaction of itaconic acid and glycerol (star-Ita.Gly). In order to decrease the viscosity of the resin, the carboxyl groups of the oligomers were reacted with ethanol (Tstar-Ita.Gly). Chemical structures of the resins were studied by 1H and 13C NMR and Fourier-transform infrared spectroscopy (FT-IR). The curing process was optimized by studying the residual exotherms during the curing process. Thermomechanical properties of the cured samples were studied by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). Thermogravimetric analyses (TGA) were also carried out on both treated and pure resins to study the thermal stability of the cured samples. The viscosity of both resins were measured at different temperatures and different stress levels. Water adsorption tests were also carried out to check the water absorption properties of Tstar-Ita.Gly’s cured samples. The viscosity of the star-Ita.Gly was 154.9 Pa s at room temperature which dropped to 1.8 Pa s upon increasing the temperature to 70 °C. The viscosity of the Tstar-Ita.Gly resin was 0.35 Pa s at room temperature, and 0.04 Pa s at 70 °C. The glass temperature (Tg) of the alcohol-treated resin was 122 °C. Fully biobased content and inexpensive raw materials, biodegradability, very good thermomechanical and comparably very promising rheological properties and processability along with good thermal stability are of advantages of the synthesized resin which make the resin comparable with other thermosetting systems as well as the commercial unsaturated polyester resins.