Sandwich-structure inspired super-tough and fire-resistant plywood containing vinyl acetate-ethylene based adhesive reinforced by melamine amino trimethyl phosphate and sodium lignosulfonate

Abstract

The flammability of wood composite materials inevitably limits its broadly applications, inspired by the sandwich structure, we propose an intumescent flame-retardant vinyl acetate-ethylene based adhesive reinforced by melamine amino trimethyl phosphate and sodium lignosulfonate compounds (IFRs), then being incorporated in adhesive layer to prepare fire-proofing plywood. The formaldehyde-free adhesive incorporated with 23 wt% IFRs in plywood (FR plywood) resulted in a significant reduction in the peak heat release rate (pHRR, −51 %) and a great delay in time to pHRR (219 s) compared with that of the sample neat plywood. Additionally, the shear strength and bending strength of sample FR plywood present significant increase of 150 % and 73 %, respectively, compared to that of the neat plywood. By incorporating the IFRs into the plywood adhesive layers, low-flammability gasses can be released under heat to dilute flammable volatile gasses together with the wood decomposition in the gaseous phase, simultaneously, generated polyphosphoric acids to facilitate the charring of wood under heat, leading to a cohesive and dense phospho-carbonaceous structure in the condensed phase. Thus, this work provides an efficient and simple strategy to prepare fire-proofing plywood with excellent mechanical performance, is worth commercializing in plywood industry.