Biomimetic soil-root-mineral system toward VER composites with enhanced mechanical property, good recyclability and excellent flame retardancy

The inherent flammability, poor mechanical property and non-recyclability of vinyl resins (VER) has hindered their widely use in aerospace and construction applications. In this work, inspired by the soil-root-mineral synergy in natural ecosystems, a novel P-N flame retardant (AT) was covalently immobilized within the polymer matrix, mimicking root anchoring in soil. Concurrently, functionalized glass fibers (FGF) were incorporated, analogous to mineral particles, to synergistically enhance the flame retardancy and mechanical reinforcement for VER. When incorporating 14 wt% AT and 1 wt% FGF, the composite achieved a UL-94 V-0 rating with a limiting oxygen index (LOI) of 31.3%. Cone calorimetry test (CCT) revealed that the VERAT/FGF 1 composite exhibited significant reductions in heat release rate (HRR), total heat release (THR), and smoke production rate (SPR) of 54.4%, 39.3%, and 20.1%, respectively, compared to pure VER. Comprehensive analyses demonstrated that the flame-retardant mechanism involved synergistic effects in both condensed and gas phases. Simultaneously, the VERAT/FGF 1 composite demonstrated 41.9% and 10.7% enhancements in tensile strength and impact resistance, respectively, compared to neat VER. Chemical degradation of VERAT/FGF 1 by solvent method for efficient recycling of glass fibers, providing a new strategy for reuse of vinyl polyester composites.