Qilu Qin,Chongwei Tian,Xiangchao Pang,Zhilin Liu,Jianxin Yin,Xiaofeng Hao,Yuan Zhu,Xianjun Li
The fabrication of flame-retardant, mold-resistant, and dimensionally stable wood using a one-step soaking process remains an imperative yet challenging goal. In this study, we developed a stable ternary composite solution system containing flame retardants (ammonium polyphosphate, boric acid, and borax), biocides (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one and 2-octyl-4-isothiazolin-3-one), and a dimensional stabilizer (N-methylol acrylamide), which was employed for the soaking treatment of wood veneer for 2 h, followed by oven curing at 80 °C for 12 h. The limiting oxygen index of the optimal wood veneer reached 34.4 %, while shrinkage and expansion ratios were 2 % and 3 %, respectively. The optimal wood veneer exhibited 100 % anti-mold efficacy against Aspergillus niger , even after leaching tests. Plywood manufactured from the modified veneer retained the enhanced flame retardancy, mold resistance, and dimensional stability. The synergistic effects of the ternary system and the efficiency of the one-step approach highlight its potential for producing durable, high-performance wood products for demanding applications. This method offers an eco-friendly solution to enhance wood safety and longevity in construction and furniture industries.
Through the substitution reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and sodium lignosulfonate (LS), a novel phosphorus-containing sodium lignosulfonate (DAL) was successfully synthesized via the solvothermal method and used as a multifunctional flame retardant to prepare a novel silicone-acrylic emulsion (SAE) composite Si–P–C coating. The structure of DAL was determined by X-ray diffraction (XRD), attenuated total reflection infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance (solid-state 13C NMR and 31P NMR). The results demonstrated that incorporating an appropriate dosage of DAL (0.9 g, 1.5 wt %) into SAE-based composite coatings enhances flame retardancy and reduces heat release and smoke production during burning. The peak heat release rate (p-HRR) decreases from 236.7 to 120.3 kW·m–2, total smoke production (TSP) decreases by 71.1%, and the flame-retardant index increases from 1.00 to 4.58. Meanwhile, the coating is transformed into a dense and nonflammable vitreous polyphosphate barrier layer during the firing process to prevent heat or mass transfer. Furthermore, the pyrolysis kinetics identify that the 3D Z–L–T model governs the coatings’ pyrolysis, and the appropriate DAL makes the pyrolysis Eα climb from 300.98 to 331.30 kJ·mol–1 at 358–439 °C. Hence, this study presents a new synthesis method of multifunctional flame retardant DAL, studies the excellent properties and cross-linking mechanism of DAL-doped SAE-composite Si–P–C coatings, and explores a halogen-free, low-carbon, and clean eco-technology strategy.
Jinhan Lu,Xuan Sun,Zhilin Chen,Peng Jiang,Luming Li,Maohai Wang
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.
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