Abstract
Inorganic impregnation strengthening of Chinese fir wood was carried out to improve the strength, dimensional stability, flame retardancy, and smoke suppression of Chinese fir wood. Sodium silicate was used as reinforcement, a sulfate and phosphate mixtures were used as a curing agent, and Chinese fir wood was reinforced by the respiratory impregnation method (RIM) that imitating human respiration and vacuum progressive impregnation method (VPIM). The weight percentage gain (WPG), density increase rate, distribution of modifier, bending strength (BS), compressive strength (CS), hardness, and water resistance of unreinforced Chinese fir wood from the VPIM and RIM were compared. It was found that RIM could effectively open the aspirated pits in Chinese fir wood, so its impregnation effect, strengthen effect and dimension stabilization effects were the best. RIM-reinforced Chinese fir wood was filled with silicate both horizontally and vertically. At the same time, the transverse permeability of silicate through aspirated pits was significantly improved. The chemical structure, crystalline structure, flame retardancy, smoke suppression, and thermal stability of VPIM- and RIM-reinforced Chinese fir wood were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), cone calorimeter (CONE), and thermogravimetric analysis (TGA). The results indicated that although the crystallinity of RIM-reinforced Chinese fir wood decreased the most, more chemical crosslinking and hydrogen bonding were formed in the wood, and the strengthen effect was still the best. Compared with VPIM-reinforced Chinese fir wood, RIM-reinforced Chinese fir wood had lower heat release rate (HRR), peak-HRR, mean-HRR, total heat release (THR), smoke production rate (SPR), and total smoke production (TSP), higher thermal decomposition temperature and residual rate. It was indicated that RIM-reinforced Chinese fir wood was a better flame retardant, and has a smoke suppression effect, thermal stability, and safety performance in the case of fire.
Funding source: Key Laboratory of Bio-based Material Science & Technology (Northeast Forestry University) Ministry of Education of the People's Republic of China
Award Identifier / Grant number: SWZ-MS201917
Funding source: Hunan Provincial Technical Innovation Platform Talent Program in Science and Technology
Award Identifier / Grant number: 2019RS2040
Funding source: Major Science and Technology Program of Hunan Province
Award Identifier / Grant number: 2017NK1010
Funding source: National Natural Science Foundation of China
Award Identifier / Grant number: 31770606
Funding source: Hunan Province Innovation Foundation for Postgraduate
Award Identifier / Grant number: CX20190600
Funding source: Central South Forestry University of Science and Technology
Award Identifier / Grant number: CX20191010, CX20192003
Author contribution: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: This research was supported by the Key Laboratory of Bio-based Material Science & Technology (Northeast Forestry University), Ministry of Education of the People’s Republic of China (SWZ-MS201917), Hunan Provincial Technical Innovation Platform and Talent Program in Science and Technology, PR China (2019RS2040), Major Science and Technology Program of Hunan Province, PR China (2017NK1010), National Natural Science Foundation of China (31770606), Hunan Province Innovation Foundation for Postgraduate, PR China (CX20190600) and Science and Technology Innovation Project for Postgraduates of Central South Forestry University of Science and Technology, PR China (CX20191010, CX20192003).
Conflict of interest statement: The authors declare no conflicts of interest.
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