scholarly journals Functionalized Surface Layer on Poplar Wood Fabricated by Fire Retardant and Thermal Densification. Part 1: Compression Recovery and Flammability

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 955 ◽  
Author(s):  
Demiao Chu ◽  
Jun Mu ◽  
Stavros Avramidis ◽  
Sohrab Rahimi ◽  
Shengquan Liu ◽  
...  
Keyword(s):  
Surface Layer ◽  
Combined Treatment ◽  
Surface Hardness ◽  
Treated Wood ◽  
Fire Retardant ◽  
Densified Wood ◽  
Fire Retardancy ◽  
Alternative Approach ◽  
Vertical Density ◽  
Functionalized Surface

To enhance compression stability and fire retardancy of densified wood, a new modification method i.e., combined nitrogen–phosphorus (NP) fire retardant pre-impregnation with surface thermo-mechanical densification is used to fabricate a certain thickness of functionalized surface layer on poplar. This combined treated wood is investigated via vertical density profile (VDP), and the compression stability is revealed by both soaking test and cone analysis. Results demonstrate that the combined treatment hardened the surface of wood and reformed the interface combination of the NP with the wood cell wall, thus making the surface tissue more close-grained. Fire retardancy was also enhanced; the total heat release and CO generation values decreased by 21.9% and 68.4%, respectively, when compared with that of solely NP-treated wood. Moreover, surface hardness increased by 15.8%, and the recovery of surface hardness and thickness were 56.8% and 77.2% lower than that of simply densified wood. It appears that this NP-involved thermal densification could be considered as an alternative approach to enhance both the compression stability and fire resistance of wood.

scholarly journals Functionalized Surface Layer on Poplar Wood Fabricated by Fire Retardant and Thermal Densification. Part 2: Dynamic Wettability and Bonding Strength

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 982 ◽  
Author(s):  
Demiao Chu ◽  
Jun Mu ◽  
Stavros Avramidis ◽  
Sohrab Rahimi ◽  
Shengquan Liu ◽  
...  
Keyword(s):  
Contact Angle ◽  
Surface Layer ◽  
Surface Energy ◽  
Bonding Strength ◽  
Sessile Drop ◽  
Combined Treatment ◽  
Treated Wood ◽  
Fire Retardant ◽  
Tangential Section ◽  
Droplet Volume

In continuation of our former study on a novel combined treatment of nitrogen–phosphorus fire retardant and thermomechanical densification on wood, this study focuses on the dynamic wettability and the bonding strength. The contact angle was measured using the sessile drop method and the surface energy was calculated according to the van Oss method. Water surface penetrating and spreading is analyzed by both the Shi and Gardner model and the droplet volume changing model. The results reveal that the combined treatment increased the surface energy, especially the acid–base component. The contact angle declined and the water droplet spread more easily on the surface. Meanwhile, the rate of relative droplet volume decreased by 32.6% because the surface layer was densified and stabilized by the combined process. Additionally, the surface possesses the lowest roughness and highest abrasion resistance on the tangential section. Thus, the bonding strength of the combined treated poplar decreased by 29.7% compared to that of untreated poplar; however, it is still 53.3% higher than that of 220 °C heat-treated wood.

Combustion behavior of oak wood (Quercus mongolica L.) modified by 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU)

Holzforschung ◽  
2014 ◽  
Vol 68 (8) ◽  
pp. 881-887 ◽  
Author(s):  
Yanjun Xie ◽  
Na Liu ◽  
Qingwen Wang ◽  
Zefang Xiao ◽  
Fengqiang Wang ◽  
...  
Keyword(s):  
Combined Treatment ◽  
Treated Wood ◽  
Fire Retardant ◽  
Untreated Wood ◽  
Cone Calorimetry ◽  
Oak Wood ◽  
Quercus Mongolica ◽  
Combustion Behavior ◽  
Service Period ◽  
Public Areas

Abstract The modification of wood with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) is an efficient strategy to improve its dimensional stability and durability during its service period. In this study, oak wood (Quercus mongolica L.) was treated with DMDHEU and the combustion behavior of the treated wood was examined. The bench-scale thermogravimetry and cone calorimetry showed that the treatment with DMDHEU alone enhanced the flammability of wood, but a combined treatment with DMDHEU and traces of magnesium chloride as a catalyst lowered the flammability to the level of untreated wood. In full-scale fire tests for flooring materials, it could be confirmed that both the untreated and treated woods have similar combustion behavior and can be classified as Dfl-S1 (capable of resisting a small flame and, for a certain period, a heat flux attack; the total smoke production is limited). Accordingly, further fire-retardant treatments may be required if DMDHEU-treated wood is used in public areas.

Promotion effect of NP fire retardant pre-treatment on heat-treated poplar wood. Part 2: hygroscopicity, leaching resistance, and thermal stability

Holzforschung ◽  
2017 ◽  
Vol 71 (3) ◽  
pp. 217-223 ◽  
Author(s):  
Demiao Chu ◽  
Jun Mu ◽  
Li Zhang ◽  
Yushuang Li
Keyword(s):  
Thermal Stability ◽  
Moisture Absorption ◽  
Degradation Products ◽  
Combined Treatment ◽  
Treated Wood ◽  
Fire Retardant ◽  
Crystallinity Index ◽  
Hydroxyl Groups ◽  
Heat Treated ◽  
Wood Polysaccharides

Abstract In continuation of the previous study concerning the effects of a combined treatment of wood with nitrogen-phosphorus (NP) fire retardant and heat treatment (HT), the hygroscopicity, leachability, thermal stability, Fourier transform-infrared (FT-IR) spectra, and X-ray diffraction (XRD) properties of Populus beijingensis W.Y. Hsu have been investigated. The wood samples were impregnated with 10% NP fire retardant solution and exposed to HTs at 140°C–160°C for 30 min. HT of NP treated wood reduced the moisture absorption and enhanced the leaching resistance of NP and improved the thermal stability. The HT decomposes the NP and the acidity of these degradation products has a dehydration effect on the wood polysaccharides, and the number of hydroxyl groups in wood decreased substantially. The crystallinity index of the NP-impregnated and heat-treated wood also increased. The post low-temperature HT enhanced the fixation of the NP fire retardant and hydrophobicity of the NP-treated wood.

Increasing Hardness of Surface Layer of Low-Carbon Steel by Account of Plasma Treatment of Coating Modification

2021 ◽  
Vol 316 ◽  
pp. 794-802
Author(s):  
Andrey E. Balanovsky ◽  
Van Trieu Nguyen
Keyword(s):  
Surface Layer ◽  
Thermal Treatment ◽  
Plasma Treatment ◽  
Plasma Heating ◽  
High Surface ◽  
Surface Hardness ◽  
High Hardness ◽  
Diffusion Region ◽  
Low Carbon ◽  
Wide Range

The Purpose of paper is to conduct studies to assess the possibility of increasing the hardness of the surface layer of steel St3 grade by plasma heating of the applied surface coating containing powder alloy PR-N80X13S2R. Mixtures of pasta were divided into 2 groups: for furnace chemical-thermal treatment and plasma surface melting. The study of the microstructure showed a difference in the depth of the saturated layer, depending on the processing method, during chemical-thermal treatment-1 mm, plasma fusion - 2 mm. The results of measuring the surface micro-hardness showed that, the obtained coating from a mixture of PR-N80X13S2R + Cr2O3 + NH4Cl has a uniform high surface hardness (31-64 HRC), from a mixture of only PR-N80X13S2R - the surface hardness varies in a wide range (15-60 HRC). The study of the microhardness of the cross section of the surface layer showed that, the diffusion region: from a mixture of powder PR-N80X13S2R + Cr2O3 + NH4Cl has uniform hardness (450-490 HV); from a mixture of PR-N80X13S2R - hardness increases in the depth of the molten region (from 300 to 600 HV), and sharply decreases in the heat affected zone (210-170 HV). The use of PR-N80X13S2R alloy powder as the main component in the composition of the paste deposited on the St3 surface during plasma treatment leads to the formation of a doped surface layer with high hardness.

scholarly journals Fire Retardancy of Fire-retardant-impregnated Wood after Natural Weathering I.

2018 ◽  
Vol 64 (3) ◽  
pp. 105-114 ◽  
Author(s):  
Masayuki Kawarasaki ◽  
Ryoichi Hiradate ◽  
Yasushi Hirabayashi ◽  
Shinichi Kikuchi ◽  
Yoshifumi Ohmiya ◽  
...  
Keyword(s):  
Fire Retardant ◽  
Natural Weathering ◽  
Fire Retardancy ◽  
Impregnated Wood

scholarly journals Enhancement of Wood Biological Resistance and Fire Retardant Properties after Laccase Assisted Enzymatic Grafting

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1102
Author(s):  
Cristian Bolaño ◽  
Sabrina Palanti ◽  
Luigi Benni ◽  
Diego Moldes
Keyword(s):  
Silver Nanoparticles ◽  
Flame Retardant ◽  
Toxic Substance ◽  
Treated Wood ◽  
Fire Retardant ◽  
Wood Preservative ◽  
Decay Resistance ◽  
Kraft Lignin ◽  
Fire Retardant Properties ◽  
Wood Surfaces

Several treatments of wood, based on laccase assisted grafting, were evaluated in this paper. Firstly, the efficacy of lignosulfonate and kraft lignin from Eucalyptus spp. as a wood preservative was assessed. Both ligno products were anchored to wood surfaces via laccase treatment in order to avoid leaching. Moreover, some of these wood preservative treatments were completed with the addition of silver nanoparticles. For comparison, a commercial product was also analyzed in terms of its fungal decay resistance during surface application, in accordance to use class 3, CEN EN 335. Secondly, the anchoring of a flame retardant based on tetrabromobisphenol-A (TBBPA) was attempted, to limit the dispersion of this toxic substance from treated wood. In both cases, kraft lignin and lignosulfonate showed an improvement in wood durability, even after leaching. However, the addition of silver nanoparticles did not improve the efficacy. On the other hand, the efficacy of TBBPA as a flame retardant was not improved by grafting it with laccase treatment or by adding O2, a co-factor of laccase.

Heat Effects on Fire Retardant-Treated Wood

1990 ◽  
Vol 8 (6) ◽  
pp. 405-420 ◽  
Author(s):  
Eugene A. Pasek ◽  
Craig R. Mcintyre
Keyword(s):  
Treated Wood ◽  
Fire Retardant ◽  
Heat Effects

BRIGHT LUMINESCENCE OF FIRE RETARDANT ALUMINUM HYDROXIDE-SILICA SPHERE COMPOSITE

2018 ◽  
Vol 25 (06) ◽  
pp. 1850113
Author(s):  
HA-SUNG KONG ◽  
BYOUNG-JU KIM ◽  
KWANG-SUN KANG
Keyword(s):  
Aluminum Hydroxide ◽  
Color Change ◽  
Fire Retardant ◽  
Excitation Wavelength ◽  
Silica Spheres ◽  
Fire Retardancy ◽  
Characteristic Absorption ◽  
Excess Amount ◽  
Mg Addition ◽  
Bright Luminescence

Bright luminescence was achieved with excess amount of aluminum hydroxide with silica spheres. Various amounts of aluminum hydroxide were attached to silica spheres to improve the performance of fire retardancy. Although silica spheres attached with 60[Formula: see text]wt.% of AlCl3 (AlOH-A) showed no color change and luminescent chromophores, silica spheres attached with 80[Formula: see text]wt.% of (AlOH-B) and 100% of (AlOH-C) of AlCl3 changed the color and produced luminescent chromophores. The solution colors became intense yellow and brown for AlOH-B and AlOH-C, respectively, after 15 days. The FTIR spectra showed the characteristic absorption peaks of Al–OH and Si–O–Al. The concentration dependent photoluminescence (PL) intensities were continuously increased until 242[Formula: see text]mg addition of the colored solution and then slightly decreased thereafter for both AlOH-B and AlOH-C. The PL peaks shifted toward red by increasing the excitation wavelength for both AlOH-B and AlOH-C. Large Stoke shifts, such as 73 and 68[Formula: see text]nm for AlOH-B and AlOH-C, respectively, were observed.

scholarly journals Basal Surface-Layer Properties in Flowing Snow

1983 ◽  
Vol 4 ◽  
pp. 158-162 ◽  
Author(s):  
T. E. Lang ◽  
J. D. Dent
Keyword(s):  
Surface Layer ◽  
Velocity Profile ◽  
Kinematic Viscosity ◽  
Granular Layer ◽  
Strong Dependence ◽  
Surface Hardness ◽  
Laboratory Simulation ◽  
Shear Locking ◽  
Low Velocity ◽  
Basal Surface

Experiments on the behavior of the active granular layer between flowing snow and sintered basal snow were performed by laboratory simulation of the layer. Layer thickness, its velocity profile, kinematic viscosity, and shear locking stress were estimated fron low-velocity tests. Variation in these parameters over a temperature range from -5 to -18°C, for overburden pressures of 1180 and 2360 N m−2, and for surface hardness in the range 0.4 to 4.0 N m−2 were evaluated. Results show strong dependence between surface hardness and layer viscosity, and near linear dependence between shear locking stress and overburden pressures.

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