Structure–properties‐performance relationships in complex epoxy nanocomposites: A complete picture applying chemorheological and thermo‐mechanical kinetic analyses

Abstract

AbstractHerein the kinetics of network formation (cross‐linking) and network degradation (thermal decomposition) in a complex system based on epoxy resin reinforced with hyperbranched amino polymer‐functionalized nanoparticles (HAPF) were discussed. Five classes of nanoparticles, that is, nano‐SiO2, halloysite nanotubes (HNTs), HNTs@nano‐SiO2 core/shell, HAPF/nano‐SiO2, HAPF/HNTs@nano‐SiO2 core/shell were loaded at 0.5, 1.0, 2.0 (optimal loading among prepared samples), and 5 wt% were examined. Parameters of the cure kinetics and degradation were correlated, and the mechanical properties were interpreted in terms of microstructure and rheological analyses. The isothermal chemorheological cure kinetics study (60, 70, and 80°C) revealed a low activation energy for epoxy/HAPF/HNTs@nano‐SiO2 core/shell nanocomposite (72.21 kJ/mol), compared with the blank epoxy (79.99 kJ/mol). Correspondingly, gel time of the system decreased from 1040 to 515 to 237 s upon isotherms of 60, 70, and 80°C, respectively. Tensile strength was also increased vividly (ca. 32%), possibly due to the strong interfacial adhesion, which reflected in an induced shear yielding. Nitrogen‐mediated thermal decomposition kinetics suggested an average degradation activation energies of ca. 150 and 210 kJ/mol for the assigned nanocomposites and the blank epoxy, respectively. Overall, there was a complete agreement between the kinetics of network formation and network degradation in the studied epoxy nanocomposite. This work enables understanding of structure‐properties‐performance in complex epoxy nanocomposites.