Synergic flame-retardant effect of cellulose nanocrystals and magnesium hydroxide in polyurethane wood coating

作者：Liangsong Cheng, Shaobo Ren, Nicolas Brosse, Zehui Ju, Su‐Xia Li, Xiaoning Lu · 发表于：Journal of Wood Chemistry and Technology · 年份：2022 · DOI：10.1080/02773813.2022.2085748 · 被引用次数：12 · 研究领域：Flame retardant materials and properties、Polymer composites and self-healing、Advanced Cellulose Research Studies

In this paper, a wood coating based on waterborne polyurethane (WPU)/nano-cellulose crystalline (CNC)/Magnesium hydroxide (MH) was prepared. Efficient dispersion of MH in WPU in presence of 5 wt% of CNCs was observed by biological microscope leading to a material with improved esthetic, thermal and fire-retardant properties and mechanical performance. By thermogravimetric analysis (TG/DTG) and comparison with WPU, the maximum weight loss rate (RTmax) of WPU/CNC/MH coating decreased dramatically from 13.2 to 6.63, and the residue increased sharply from 4.69% to 40.55%. The results of pyrolysis combustion flow calorimeter (PCFC) showed that the flame-retardant performance of the composite coating is also greatly improved, and the peak of heat rate release (pHRR) being reduced from 350 w/g to 121 w/g. When applied to the wood panels, according to the Limiting oxygen index (LOI) experiment, for MH < 40 wt%, the combustibility grade is B2 level (combustible material), whereas for MH > 40 wt% the grade is B1 level (flame retardant material).