Epoxy thermosets have revolutionized the coating, adhesive, and composite industries but the chemicals from which they are synthesized have significant effects on the environment and human health. This problem is only exacerbated when a high glass transition temperature and temperature of thermal degradation are desired for the material. In this study, we propose a generally regarded as safe, FDA approved for consumption polyphenolic molecule tannic acid (TA) as an alternative epoxy hardening agent for commercially available epoxy resin, the diglycidyl ether of bisphenol A (DGEBA). The resulting thermosets were characterized by fourier transform infrared (FTIR) spectroscopy, optical microscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results from this study showed that the resulting TA-hardened epoxy samples had increased mechanical properties and glass transition temperatures as compared to commercial epoxy thermosets that were amine hardened, but these properties could be tuned by the degree of TA loading into the samples. Further, it was discovered that at high loading levels, the resulting materials had glass transition temperatures in the range of several high transition epoxy polymers that were commercially available. The resulting material is a more sustainable alternative to amine or acid hardened epoxy thermosets and was particularly useful in high temperature, high load-bearing applications.

Tannic acid: A sustainable crosslinking agent for high glass transition epoxy materials

255th National Meeting (2018)

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