Hybrid approach to improve the flame-retardant and thermal properties of sustainable biocomposites used in outdoor engineering applications

We present the development of a high-performance flame-retardant vinyl ester (FR-VE)/flax fabric (FF) biocomposite through a hybrid approach using vacuum-assisted resin transfer molding. FF was modified to form FR fibers (mFF) using surface treatment with varying amounts (5-20%) of ammonium polyphosphate (APP), and the FR-VE/mFF composites were fabricated by including flame retardants such as chitosan (CS), APP, and modified CS (NCSAPP). The optimized mFF (15% APP) exhibited enhanced thermal stability (38 wt% residue at 700 degrees C) and it achieved a V0 rank in the UL 94 test. In addition, the dual effects, i.e., the effects modification of the reinforcement and inclusion of the FRs into the matrix, improved the properties of the FR-VE/mFF composites, providing them with high thermal resistance (28 wt% residue at 700 degrees C), and fire resistance (V0 rank in the UL 94 test), and self-extinguishing characteristics with a suppressed peak heat release rate (69%), total heat release, and smoke production rate.

Automated summary

A high-performance flame-retardant vinyl ester/flax fabric biocomposite was developed using vacuum-assisted resin transfer molding, with modified flax fabric exhibiting enhanced thermal stability and achieving a V0 ranking in fire resistance tests. The inclusion of flame retardants further improved the properties of the composite, providing high thermal resistance, fire resistance, and self-extinguishing characteristics.