Role of curing kinetics and thermodynamics in the thermal and mechanical properties of DGEBA / PEG ‐ PPG ‐ PEG blends

The main objective of this work was to investigate the influence of mixture temperatures on the thermal and mechanical properties of epoxy resin with the addition of a block copolymer. The triblock copolymer used in this study was composed of poly(ethylene glycol)/poly(propylene glycol)/poly(ethylene glycol) (PEG‐ b ‐PPG‐ b ‐PEG) with a molecular weight of 14 600 g mol −1 and 82.5% (w/w) PEG. This copolymer was incorporated into the epoxy resin at a concentration of 10% by weight. Due to possible miscibility and immiscibility properties of the triblock copolymer in diglycidyl ether of bisphenol A resin, two polymer blending methods (80 and 100 °C) were employed. The mixing temperature was observed to influence the glass transition temperature, with a decrease of 32 °C for the mixture prepared at 80 °C compared to the neat resin. For the mixing process at 100 °C, an 87% increase in fracture toughness was observed. A tradeoff between thermodynamics and curing kinetics was fundamental to these results. The curing kinetics, which are highly temperature dependent, govern the rate and extent of polymerization reactions. In contrast, thermodynamics governs solubility, and both factors interact to define the final structure and properties of the material.