Kinetics of curing and thermo-degradation, antioxidizing activity, and cell viability of a tannic acid based epoxy resin: From natural waste to value-added biomaterial

This work outlines the preparation and characterization of a novel bio-based epoxy resin derived from tannic acid (TA). The TA-based epoxy resin (ETA) was firstly synthesized via glycidylation by epichlorohydrin, and then spectrally characterized by FTIR. The thermal properties of the bio-resin were evaluated by DSC, TGA and OIT analyses. The curing kinetic parameters calculated by the Vyazovkin's advanced isoconversional method showed that ETA had a different activation energy dependency on conversion compared with the conventional petroleum-based epoxy resin, i.e., diglycidylether bisphenol A, Epikote 828. The bio-resin exhibited good thermal stability and higher char yield comparing to the petro-based one. Pyrolysis-GC/MS was used to evaluate the thermal degradation products of the bio-resin. The biocompatibility properties evaluated by L929 fibroblast cells viability revealed no cytotoxicity. ETA was also found to be an effective antioxidant material. The research promised new generation of epoxy thermosets comprising natural based phenolic compounds without toxic bisphenol A, which could be used in biomaterials, electrical circuit boards, or inherent antioxidants.