The Study of Functional Glass Fiber Veils for Composites Protection: Flame Resistance and Mechanical Performance

The flame-retardant performance of carbon fiber-reinforced composites is crucial for ensuring structural stability. Traditional additive flame-retardant methods often struggle to balance structural integrity with fire resistance. Herein, Ni(OH)2and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were used as flame-retardant agents and mixed with glass fibers to construct the flame-retardant functional fiber veil which was used as the skin layer on the composite surface for fire protection. The structure performance and flame retardancy of composites were characterized via Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and a cone calorimeter test. The results confirmed that a flame-retardant glass fiber mat could effectively improve the flame-retardant and smoke-suppressive properties of the composite material. Due to the synergistic flame-retardant mechanism of Ni(OH)2and DOPO, the C-N3-D2 composite with the highest LOI value of 32.3% has shown significant reduction in peak heat release rate (PHRR) and total smoke production (TSP) by 31.3% and 19.5%, respectively. In addition, due to flame-retardant agents only being employed in the skin layer of the composite, the core layer of a carbon fiber-reinforced structure could be protected without structure disruption. This approach maintained consistent interlayer shear strength, highlighting the effectiveness of using a flame-retardant fiber veil as a protective skin layer. This strategy could offer a viable solution for safeguarding high-performance composite materials from fire hazards without compromising their structural integrity.