Fire Retardancy of Fire-retardant-impregnated Wood after Natural Weathering II.

Kawarasaki, Masayuki; Hiradate, Ryoichi; Hirabayashi, Yasushi; Kikuchi, Satoshi; Ohmiya, Yoshifumi; Lee, Jae-Young; Noaki, Masaki; Nakamura, Noboru

doi:10.2488/jwrs.66.31

Cited by 2 publications

(3 citation statements)

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“…Phosphates are very effective in enhancing the fire-retardancy of hydroxyl group-rich polymers, for example, lignocellulosic materials. This is because the phosphates can promote char formation by the dehydration of hydroxyl groups, by creating a protective glassy barrier of polyphosphates, and also by acting as radical scavengers to prevent further heat transfer. ,, However, its high leachability in water limits broader applications, as a phosphate salt can eventually be washed away by rainfall and vapor condensation in outdoor conditions, thus reducing the fire retardancy of wood materials with time. , …”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…13,18,19 However, its high leachability in water limits broader applications, as a phosphate salt can eventually be washed away by rainfall and vapor condensation in outdoor conditions, thus reducing the fire retardancy of wood materials with time. 20,21 The combination of ammonium phosphate salts with a hydrophobic resin has been considered an effective and simple approach to improve the leaching resistance of FR-modified wood, without modifying the formula of the salt. Lin et al have demonstrated that the water-leaching resistance of guanyl-urea phosphate (GUP)-treated wood can be largely improved by combining it with a water-borne melamine-formaldehyde resin or with poly(furfuryl alcohol).…”

Section: ■ Introductionmentioning

confidence: 99%

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High Leach-Resistant Fire-Retardant Modified Pine Wood (Pinus sylvestris L.) by In Situ Phosphorylation and Carbamylation

et al. 2023

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The exterior application of fire-retardant (FR) timber necessitates it to have high durability because of the possibility to be exposed to rainfall. In this study, water-leaching resistance of FR wood has been imparted by grafting phosphate and carbamate groups of the watersoluble FR additives ammonium dihydrogen phosphate (ADP)/urea onto the hydroxyl groups of wood polymers via vacuum-pressure impregnation, followed by drying/heating in hot air. A darker and more reddish wood surface was observed after the modification. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, solid-state 13 C crosspolarization magic-angle-spinning nuclear magnetic resonance ( 13 C CP-MAS NMR), and direct-excitation 31 P MAS NMR suggested the formation of C−O−P covalent bonds and urethane chemical bridges. Scanning electron microscopy/energy-dispersive X-ray spectrometry suggested the diffusion of ADP/urea into the cell wall. The gas evolution analyzed by thermogravimetric analysis coupled with quadrupole mass spectrometry revealed a potential grafting reaction mechanism starting with the thermal decomposition of urea. Thermal behavior showed that the FR-modified wood lowered the main decomposition temperature and promoted the formation of char residues at elevated temperatures. The FR activity was preserved even after an extensive water-leaching test, confirmed by the limiting oxygen index (LOI) and cone calorimetry. The reduction of fire hazards was achieved through the increase of the LOI to above 80%, reduction of 30% of the peak heat release rate (pHRR 2 ), reduction of smoke production, and a longer ignition time. The modulus of elasticity of FR-modified wood increased by 40% without significantly decreasing the modulus of rupture.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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High Leach-Resistant Fire-Retardant Modified Pine Wood (Pinus sylvestris L.) by In Situ Phosphorylation and Carbamylation

et al. 2023

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Artificial-weathering test requirements for fire-retardant-treated wood to reproduce optimal chemical retention and moisture conditions

Takase,

Ishikawa,

Kamikawa

2024

J Wood Sci

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Despite the increasing outdoor use of fire-retardant-treated wood, methods for predicting its service life remain poorly established. With the aim of establishing a method to predict chemical losses from fire-retardant-treated (FRT) wood caused by humid atmospheres and rain outdoors, this study examined the preferable conditions for artificial-weathering tests and demonstrated the acceleration coefficients in these tests (i.e., the ratio of equivalent time to reach the same retention of chemicals in artificial weathering and outdoors) based on the EN927-6 standard. To determine the moisture absorption and desorption levels of FRT exposed to outdoor conditions, an outdoor exposure experiment was conducted. The moisture content was higher in the FRT wood than in untreated wood, regardless of the type of coating, and ranged between 11% (in March) and 50% (in September) of the untreated wood’s weight. EN927-6 artificial weathering tests were performed on two groups of specimens with initial moisture contents of 0% and 25%. Retention rates of fire-retardant chemicals after a 2520-h test were compared with those retrieved from 4-year outdoor exposure reported elsewhere. Comparison of these two experiments demonstrated that the acceleration coefficients were 4.1–11.3 in the case of specimens with 0% initial moisture content and 5.1–11.4 in the case of specimens with 25% initial moisture content. The higher initial moisture content produced a more uniform acceleration coefficient. Nevertheless, larger acceleration coefficients were derived from specimens with penetrating or semi-film-forming coatings in both cases. The relationships between the uniformity of this acceleration coefficient and the initial moisture content are discussed from the moisture absorption experiment under constant temperature and humidity and under condensation conditions.

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Fire Retardancy of Fire-retardant-impregnated Wood after Natural Weathering II.

Cited by 2 publications

References 0 publications

High Leach-Resistant Fire-Retardant Modified Pine Wood (Pinus sylvestris L.) by In Situ Phosphorylation and Carbamylation

High Leach-Resistant Fire-Retardant Modified Pine Wood (Pinus sylvestris L.) by In Situ Phosphorylation and Carbamylation

Artificial-weathering test requirements for fire-retardant-treated wood to reproduce optimal chemical retention and moisture conditions

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