In Situ-Generated Heat-Resistant Hydrogen-Bonded Organic Framework for Remarkably Improving Both Flame Retardancy and Mechanical Properties of Epoxy Composites
Yingbing Zou, Wenqi Cui, Denglong Chen, Fubin Luo, Hongzhou Li
Abstract
In this study, the heat-resistant hydrogen-bonded organic framework (HOF) material HOF-FJU-1 was synthesized via in situ generation and then used as flame retardants (FRs) to improve the flame retardancy of epoxy resin (EP). HOF-FJU-1 can maintain high crystallinity at 450 °C and thus function as a flame retardant in EP. The study found that HOF-FJU-1 facilitates the improvement of char formation in EP, thus inhibiting heat transfer and smoke release during combustion. For EP/HOF-FJU-1 composites, the in situ-generated HOF-FJU-1 can remarkably improve both the mechanical properties and the flame retardancy of EP. Furthermore, the in situ-generated HOF-FJU-1 has better fire safety than the ex situ-generated HOF-FJU-1 at the same filling content. Thermal degradation products and flame retardation mechanisms in the gas and condensed phases were further investigated. This work demonstrates that the in situ-generated HOF-FJU-1 is promising to be an excellent flame-retardant candidate.