Thermo-mechanical properties of rosin-modified o-cresol novolac epoxy thermosets comprising rosin-based imidoamine curing agents

Rosin-modified o-cresol novolac epoxy resin (AEOCN) was synthesized by condensation of rosin acid with o-cresol formaldehyde novolac resin (AOCN). The AEOCN resin was further epoxidized using epichlorohydrin and sodium hydroxide. Rosin-based imidoamine curing agents (IAMDK, IASDK, and IAEDK) were also prepared by reacting dimaleopimaryl ketone (DMPK), a dimerized rosin product with aromatic diamines. The chemical structures of all synthesized products were confirmed by FTIR, H-1-NMR, C-13-NMR, and DEPT-135 degrees spectroscopic techniques. The curing process of rosin-modified epoxy cured with imidoamine crosslinkers was studied using differential scanning calorimetry (DSC) and the results were compared to o-cresol novolac epoxy resin (EOCN) and some previously reported commercial-based systems. The thermal and mechanical properties of the cured epoxy thermosets were determined using a thermogravimetric analyzer (TGA) and a universal testing machine (UTM), respectively. The chemical resistance analysis was carried out by immersing cured epoxy coated panels in 1M NaOH, 1MHCl, and 1M NaCl solutions. The results were evaluated in terms of % weight loss method and the morphological changes that appeared due to chemical exposure were also investigated via scanning electron microscopy (SEM). This study presents the economical synthetic approach towards high-performance bio-based epoxy coating materials impending to replace some of the petrochemical compounds in coating industries.

Automated summary

In this study, rosin-modified o-cresol novolac epoxy resin was synthesized and further epoxidized, along with the preparation of rosin-based imidoamine curing agents. The chemical structures of all products were confirmed using spectroscopic techniques. The curing process and properties of the cured epoxy thermosets were studied, as well as chemical resistance analysis of the epoxy coated panels. This research presents an economical approach towards high-performance bio-based epoxy coating materials.