In Situ-Generated Heat-Resistant Hydrogen-Bonded Organic Framework for Remarkably Improving Both Flame Retardancy and Mechanical Properties of Epoxy Composites

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.

Self-Generation of a Nanofibrous Structure Enables Facile Preparation and Processing of a Liquid Crystalline Polymeric Composite with Intrinsic Flame Retardancy

“…It suggested that the combination of the polymer bulk and the nanofibrous structure in TLCP-N5 was conducive to the formation of a high-quality char layer, thus inhibiting the diffusion of oxygen and suppressing heat transfer during combustion . The degree of graphitization of TLCP residues was represented by the ratio of the integrated intensities of the D and G bonds (Figure F). ,, D and G bands, centered at 1360 and 1580 cm –1 in spectra, were associated with the vibration of carbon atoms in a disordered graphite structure and an ordered graphic structure, respectively. , Lower ratios of I D / I G of TLCP-N5 (1.12) than TLCP-N0 (1.44) indicated that TLCP-N5 possessed a higher graphitization degree and a more compact char layer. − Thus, the condensation phase played a dominant role in the flame-retardant mechanism of TLCP-N5. The formation of a dense char layer during burning could inhibit the combustible gaseous release and heat exchange, which is shown in Figure G.…”

Interconversion and functional composites of metal–organic frameworks and hydrogen-bonded organic frameworks

“…Similarly to metal–organic frameworks (MOFs) which can combine with other frameworks to construct superior functional materials, HOFs have also formed composites successfully with metal ions, enzymes, metal nanoparticles, polymers and covalent organic frameworks (COFs). 39–43 The combination of HOFs and MOFs has been demonstrated to effectively address the limitations of each material while enhancing the overall performance through their mutual convertibility. However, due to the relatively short development time of HOFs, there is limited research on the combination of HOFs and MOFs.…”