3D triazine-based covalent organic framework and glass fiber hybrid network for enhanced thermal insulation in polyphenylene sulfide composites

In this study, a polyphenylene sulfide (PPS)-based composite was developed by incorporating triazine-based covalent organic frameworks (TCOFs) and glass fibers (GFs) to simultaneously address the challenges of thermal insulation and flame retardancy in high-temperature environments. The TCOF structure was engineered via an Ostwald ripening process to exhibit a highly porous, partially crystalline architecture, enabling multiscale phonon scattering and effectively hindering thermal transport. In parallel, surface-modified GFs served as a reinforcing scaffold, enhancing mechanical strength and promoting the formation of a robust char layer during combustion. The resulting hybrid composites demonstrated significantly reduced thermal conductivity, reaching as low as 0.056 W·m–1·K–1, and outstanding flame retardancy, consistently achieving UL-94 V-0 ratings across all formulations. Morphological analyses confirmed the development of dense, thermally stable char structures in the presence of both fillers. Mechanical testing further revealed that the dual-filler network enhanced the storage modulus and maintained tensile performance, despite the inherent brittleness introduced by the fillers. These findings underscore the synergistic effects of TCOFs and GFs in creating multifunctional PPS composites with superior thermal insulation, flame resistance, and mechanical durability, making them strong candidates for advanced thermal management applications.