The curing and degradation kinetics of modified epoxy–SiO2 composite

Abstract

Composites (SiO2-EC) were prepared by 4,5-epoxycyclohexane 1,2-dicarboxylic acid dilycidyl (TDE-85) epoxy resin in the presence of SiO2 and cured by 2-aminobenzothiazole (2-ABZ). The curing kinetics and degradation kinetics of SiO2-EC were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), respectively. Then, the kinetic parameters were evaluated using non-isothermal mode and several kinetic methods, including Flynn–Wall–Ozawa (FWO), Friedman–Reich–Levi (FRL) and Malek methods. The results show that the experimental values of DSC and TG can be well described by autocatalytic model and nth model, respectively. The obtained equation of autocatalytic model is \(\frac{{{\text{d}}\alpha }}{{{\text{d}}t}} = 1.921 \times 10^{8} \exp \left( { - \frac{{6.783 \times 10^{4} }}{{{{R}}T}}} \right)\alpha^{0.995} (1 - \alpha )^{1.910}.\) All of these results are beneficial for studying the application of modified epoxy–SiO2 composite. A reliable and reasonable curing process between T i0 (379 K) and T f0 (472 K) is obtained by using extrapolation method. The cured SiO2-EC (the content of SiO2 is 25%) that exhibits excellent thermal stability with the initial decomposition temperature at 5% mass loss (IDT) is 572 K, increasing about 11 K compared with pure epoxy resin. It may be contributed to the reasonable and effective curing process obtained from the studying of curing kinetics of SiO2-EC and the synergistic effects obtained via the incorporation of SiO2.