Interplay of curing and thermal degradation in epoxy resins cured with amino acids: Influence of the maximum curing temperature on the network structure, crystal morphology and mechanical properties

Bio-based alternatives for epoxy resin curing agents are a necessity for fiber reinforced polymer composites to become more sustainable. Here, the precise knowledge about the optimal curing cycle and its influence on the thermoset's mechanical properties are imperative. Therefore, the influence of the maximum curing temperature on the network structure, crystal morphology and mechanical properties of diglycidyl ether of bisphenol A (DGEBA) cured with l-arginine was investigated with the goal to derive structure-property relationships and a favorable curing cycle. The maximum curing temperature used can be categorized into two regimes: first, the temperature range in which the thermoset reaches complete curing and second, the temperature regime in which the thermoset is fully cured and the thermal degradation starts to diminish its mechanical properties. An optimized curing regimen for achieving high flexural strength accompanied by adequate fracture toughness entails subjecting the material to a curing cycle comprising a duration of 1 h at a temperature of 150 & DEG;C, followed by an additional 2 h at a temperature of 170 & DEG;C. This study represents a pioneering effort in optimizing the curing process of amino acid-cured epoxy resin, specifically focusing on achieving the most favorable mechanical properties as a result.