Impact of Stoichiometry on the Network Structure, Properties, and Processing Relationships of an Epoxy Tannic Acid Resin System

Le résumé fourni par la source

In this work, diglycidyl ether of bisphenol A (DGEBA) is cured with the bioderived branched polyphenol tannic acid (TA) to establish the optimum composition for enhanced mechanical and thermal properties and processability. To do this, the composition of DGEBA to TA is systematically varied and the impact upon the cure kinetics, network structure, and mechanical and thermal properties is determined. As the concentration of TA increases, the mechanical and thermal properties exhibit a peak in performance corresponding to the formation of a homogeneous microstructure where the cure reaction occurs initially via the faster epoxide TA addition and then by the slower homopolymerization of the epoxy resin. Although the precise stoichiometry of the optimum formulation is unknown, given the uncertainty surrounding the reactivity of each phenolic group, this partially bioderived resin system displays properties and processability consistent with other highly aromatic and highly cross-linked fossil fuel-derived resin systems. For example, the maximum T g, determined by DMTA, is 190 °C (tan δ max), the flexural modulus is over 3 GPa, the flexural strength approaches 50 MPa, and the fracture toughness K IC is 0.6 MPa m 1/2 . Furthermore, the maximum T 5% decomposition temperature of the fully cured network is 361 °C, while the char yield is 23.9%, which is entirely consistent with the degradation properties of high-performance epoxy networks. The detailed structure–property relationships presented here are an important step in the commercial exploitation of bioderived resin systems.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.