scholarly journals Weathering Stability and Durability of Birch Plywood Modified with Different Molecular Weight Phenol-Formaldehyde Oligomers

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 175
Author(s):  
Juris Grinins ◽  
Vladimirs Biziks ◽  
Brendan Nicholas Marais ◽  
Janis Rizikovs ◽  
Holger Militz
Keyword(s):  
Uv Light ◽  
Phenol Formaldehyde ◽  
Wood Decay ◽  
Soft Rot ◽  
Solid Wood ◽  
Solid Content ◽  
Molecular Weights ◽  
Weathering Processes ◽  
Commercial Resin ◽  
D 20

This study investigated the effect of phenol-formaldehyde (PF) resin treatment on the weathering stability and biological durability of birch plywood. Silver birch (Betula pendula) veneers were vacuum-pressure impregnated with four different PF resins with average molecular weights (Mw) of 292 (resin A), 528 (resin B), 703 (resin C), and 884 g/mol (resin D). The aging properties of PF resin modified birch plywood were analyzed using artificial weathering with ultraviolet (UV) light, UV and water spray, and weathering under outdoor conditions. The same combinations of PF-treated plywood specimens were then tested in soil-bed tests to determine their resistance against soft-rot wood decay. It was not possible to compare weathering processes under artificial conditions to processes under outdoor conditions. However, the weathering stability of birch plywood treated with PF resins A, B, and C, scored better than plywood treated with commercial resin D (regardless of solid content concentration [%]). Results from unsterile soil bed tests showed improvements in resistance to soft-rot wood decay compared to untreated plywood and solid wood. Mass loss [%] was lowest for birch plywood specimens treated with resin of highest solid content concentration (resin D, 20%). Provisional durability ratings delivered durability class (DC) ratings of 2–3, considerably improved over untreated solid wood and untreated birch plywood (DC 5).

Evaluation of water related properties of birch wood products modified with different molecular weight phenol-formaldehyde oligomers

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Juris Grinins ◽  
Vladimirs Biziks ◽  
Janis Rizikovs ◽  
Ilze Irbe ◽  
Holger Militz
Keyword(s):  
Molecular Weight ◽  
Dimensional Stability ◽  
Phenol Formaldehyde ◽  
Treated Wood ◽  
Weight Percent Gain ◽  
Weight Percent ◽  
Solid Wood ◽  
Wood Products ◽  
Birch Wood ◽  
Molecular Weights

Abstract This study investigated the effect of phenol-formaldehyde (PF) resin treatment on the dimensional stability of birch solid wood and plywood. Therefore, three different low molecular weight PF resins with average molecular weights (M w ) of 292, 528, and 884 g/mol were synthesized and used for silver birch (Betula pendula) solid wood (20 × 20 × 20 mm3) and veneer (100 × 100 × 1.4 and 300 × 300 × 1.4 mm3) impregnation to produce plywood. The weight percent gain (WPG) and bulking after curing of resin treated wood specimens were determined. The leaching was performed to evaluate the PF resin fixation stability. All tested resins at all concentrations were similarly fixed in wood blocks after the leaching (1.5–2.0% WPG loss). The dimensional stability of birch wood after treatment with all tested PF resins was significantly improved. The anti-swelling efficiency (ASE) of birch wood blocks treated with PF resins after seven water soaking-drying cycles was in the range of 39–53%, 46–65% and 49–65% using 10, 15 and 20% solution concentrations, respectively. Whereas, the ASE of plywood obtained from veneers treated with 10% of PF solution was improved by 6–20%. The equilibrium moisture content (EMC) and volumetric swelling (VS) of PF treated plywood at 98% of relative humidity (RH) decreased significantly. All PF resin treated plywood surfaces were more hydrophobic compared to untreated plywood.

Importance and mobilization of nutrients in soft rot of wood

1991 ◽  
Vol 37 (11) ◽  
pp. 864-868 ◽  
Author(s):  
James J. Worrall ◽  
C. J. K. Wang
Keyword(s):  
Weight Loss ◽  
Key Words ◽  
Wood Decay ◽  
External Solution ◽  
Soft Rot ◽  
Chaetomium Globosum ◽  
Nutrient Concentrations ◽  
Nutrient Requirements ◽  
Low Levels ◽  
Scytalidium Lignicola

Soft rot of wood by Chaetomium globosum and Scytalidium lignicola was negligible in the absence of added nutrients. Independently varying the concentrations of nutrients in double Abrams' solution (which is often used for testing soft rot of wood) showed that these concentrations are higher than necessary, and in some cases supraoptimal, for soft rot as measured by weight loss. Optimal nutrient concentrations were lower in cases of low decay capacity than in cases of high decay capacity. A suitable, reduced solution contained, per litre, 1.5 g NH4NO3, 2.5 g KH2PO4, 2.0 g K2HPO4, and 1 g MgSO4∙7H2O. Best results were obtained when blocks were infiltrated with the solution. Increasing osmolality with KCl inhibited soft rot, suggesting that the solution satisfies specific nutrient requirements rather than an osmophilic requirement. P and especially N were actively mobilized into decaying blocks. As any of the nutrients were added at low levels to the external solution, decay and the influx of N increased. Key words: wood decay, soft rot, nutrients, translocation, osmophily.

Climate influences the effect of fungal decay type on regeneration of Picea jezoensis var. hondoensis seedlings on decaying logs

2020 ◽  
Vol 50 (1) ◽  
pp. 73-79
Author(s):  
Yu Fukasawa ◽  
Yoko Ando ◽  
Satoshi N. Suzuki ◽  
Mineaki Aizawa ◽  
Daisuke Sakuma
Keyword(s):  
Wood Decay ◽  
Brown Rot ◽  
Soft Rot ◽  
Climatic Conditions ◽  
White Rot ◽  
Seedling Density ◽  
Picea Jezoensis ◽  
Central Japan ◽  
Seedling Regeneration ◽  
Mountainous Regions

Hondo spruce (Picea jezoensis var. hondoensis (Mayr) Rehder)) is separately distributed among several mountainous regions in central Japan as remnant populations of the last glacial period. To identify factors that affect Hondo spruce seedling regeneration on decaying logs, we investigated the relationships between climatic conditions, log properties, including decay type by fungi, and Hondo spruce seedling density on logs using data from seven subalpine Hondo spruce forests in central Japan. The results showed that the presence of soft rot was associated with higher seedling density, and the effect of brown rot in sapwood and white rot in heartwood on the predicted number of spruce seedlings on logs switched from positive to negative with increasing temperature and precipitation. Because soft rot occurs under humid conditions, the use of forest management techniques that increase the number of logs with soft rot in sapwood (e.g., by keeping the forest floor moist) are recommended for the sustainable regeneration of Hondo spruce. However, the relationships between wood decay type and seedling regeneration can also be affected by climate condition and thus are more complex than previously thought.

scholarly journals Synthetic scheme to improve the solid content of biodegradable waterborne polyurethane by changing the association relationships of hydrophilic fragments

RSC Advances ◽  
2020 ◽  
Vol 10 (48) ◽  
pp. 28680-28694 ◽  
Author(s):  
Zhihui Yang ◽  
Guangfeng Wu
Keyword(s):  
Ethylene Glycol ◽  
Waterborne Polyurethane ◽  
Solid Content ◽  
Synthetic Method ◽  
High Solid Content ◽  
Poly Ethylene Glycol ◽  
High Solid ◽  
Molecular Weights ◽  
Waterborne Polyurethanes ◽  
Poly Ethylene

A synthetic method was developed to prepare biodegradable waterborne polyurethanes (BHPUs) with a high solid content by introducing different molecular weights of poly(ethylene glycol) (PEG) into poly(ε-caprolactone) (PCL)-based polyurethanes.

Weathering of a carbon nanotube/epoxy nanocomposite under UV light and in water bath: impact on abraded particles

Nanoscale ◽  
2015 ◽  
Vol 7 (44) ◽  
pp. 18524-18536 ◽  
Author(s):  
Lukas Schlagenhauf ◽  
Bahareh Kianfar ◽  
Tina Buerki-Thurnherr ◽  
Yu-Ying Kuo ◽  
Adrian Wichser ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Surface Properties ◽  
Uv Light ◽  
Water Bath ◽  
Epoxy Nanocomposite ◽  
Weathering Processes ◽  
Properties Of Composites

Weathering processes can influence the surface properties of composites with incorporated nanoparticles.

The effect of phenol-formaldehyde adhesive modification with fire retardant on the properties of birch plywood

2019 ◽  
Vol 106 ◽  
pp. 197-113
Author(s):  
JAKUB KAWALERCZYK ◽  
DOROTA DZIURKA ◽  
RADOSŁAW MIRSKI ◽  
ADRIAN TROCIŃSKI ◽  
MAREK WIERUSZEWSKI
Keyword(s):  
Weight Loss ◽  
Shear Strength ◽  
Phenol Formaldehyde ◽  
Fire Retardant ◽  
Solid Content ◽  
Burned Area ◽  
Gel Time ◽  
Bonding Quality ◽  
Resin Mixture ◽  
Gelling Time

The effect of phenol-formaldehyde adhesive modification with fire retardant on the properties of birch plywood. The study investigated how the modification of phenol-formaldehyde adhesive with a mixture of potassium carbonate and urea affect the properties of plywood. Based on the investigations of the viscosity, gel time and solid content of PF resin mixture containing various amounts of modifiers with various compositions it was found that modification led to major decrease in viscosity, caused the elongation of gelling time and reduced the solid content. In all variants modification of the resin led to significant improvement in plywood flammability evaluated on the basis of parameters such as: weight loss, time of ignition and burned area. The addition of fire retardant to the resin caused a decrease of shear strength. Composition of the modifier had a significant effect on bonding quality, however all plywood samples retained good values exceeding 1 N/mm2 required by EN 314-2 (1993).

scholarly journals Characterization of heterogeneous nuclear RNA-protein complexes in vivo with monoclonal antibodies.

1984 ◽  
Vol 4 (6) ◽  
pp. 1104-1114 ◽  
Author(s):  
G Dreyfuss ◽  
Y D Choi ◽  
S A Adam
Keyword(s):  
Monoclonal Antibodies ◽  
Uv Light ◽  
Protein Complexes ◽  
Cross Linking ◽  
Intact Cells ◽  
Molecular Weights ◽  
Nuclear Rna ◽  
Nonionic Detergent ◽  
Sufficient Intensity

Exposure of cells to UV light of sufficient intensity brings about cross-linking of RNA to proteins which are in direct contact with it in vivo. The major [35S]methionine-labeled proteins which become cross-linked to polyadenylated heterogeneous nuclear RNA in HeLa cells have molecular weights of 120,000 (120K), 68K, 53K, 43K, 41K, 38K, and 36K. Purified complexes of polyadenylated RNA with proteins obtained by UV cross-linking in intact cells were used to immunize mice and generate monoclonal antibodies to several of these proteins. Some properties of three of the proteins, 41K, 43K, and 120K, were characterized with these antibodies. The 41K and 43K polypeptides are highly related. They were recognized by the same antibody (2B12) and have identical isoelectric points (pl = 6.0 +/- 0.2) but different partial peptide maps. The 41K and 43K polypeptides were part of the 40S heterogeneous nuclear ribonucleoprotein particle and appear to correspond to the previously described C proteins (Beyer et al., Cell II:127-138, 1977). A different monoclonal antibody (3G6) defined a new major heterogeneous ribonucleoprotein of 120K. The 41K, 43K, and 120K polypeptides were associated in vivo with both polyadenylated and non-polyadenylated nuclear RNA, and all three proteins were phosphorylated. The monoclonal antibodies recognized similar proteins in human and monkey cells but not in several other vertebrates. Immunofluorescence microscopy demonstrated that these proteins are segregated to the nucleus, where they are part of a fine particulate nonnucleolar structure. In cells extracted in situ with nonionic detergent, all of the 41K and 43K polypeptides were associated with the nucleus at salt concentrations up to 0.5 M NaCl, whereas the 120K polypeptide was completely extracted at this NaCl concentration. A substantial fraction of the 41K and 43K polypeptides (up to 40%) was retained with a nuclear matrix--a structure which is resistant to digestion with DNase I and to extraction by 2 M NaCl, but the 41K and 43K polypeptides were quantitatively removed at 0.5 M NaCl after digestion with RNase.

Fabrication of 3D photocatalytic α-Fe2O3 structure using direct ink writing method

2014 ◽  
Vol 28 (07) ◽  
pp. 1450051 ◽  
Author(s):  
Yayun Li ◽  
Bo Li ◽  
Longtu Li
Keyword(s):  
Uv Light ◽  
Three Dimensional ◽  
Bulk Sample ◽  
Potential Method ◽  
Optical Microscope ◽  
Solid Content ◽  
X Ray Diffraction ◽  
Direct Ink Writing ◽  
Shaping Process ◽  
Better Than

Three-dimensional (3D) photocatalytic devices are economical and environmental, since they can be easily recycled and reused. In this paper, a kind of 3D photocatalytic device with a rod diameter of 250 μm was fabricated using the aqueous-based α- Fe 2 O 3 ceramic inks by direct ink writing (DIW) method. The properties of the DIW woodpile samples were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and optical microscope. The result shows that the ink with solid content of 71.4 wt.% exhibits a shear thinning behavior and proper viscoelastic properties, which ensure a feasible extrusion in the whole shaping process. The sample sintered at 800°C in air causes photocatalytic degradation of methylene blue (MB) solution under the ultraviolet (UV) light. The photocatalytic properties of the α- Fe 2 O 3 woodpile structure was characterized by the UV-visible light spectrophotometer, and it was found to be better than that of bulk sample with same weight for its higher specific surface. The DIW technique would offer a potential method for the design and fabrication of 3D photocatalytic devices.

Triply-Responsive Poly(N,N-Dimethylaminoethyl Mathacrylate) with an Azobenzene Moiety

2010 ◽  
Vol 663-665 ◽  
pp. 1049-1052
Author(s):  
Xin De Tang ◽  
Xin Wang ◽  
Yuan Yuan Dou
Keyword(s):  
Uv Light ◽  
Aqueous Media ◽  
Gel Permeation Chromatography ◽  
Terminal Group ◽  
Light Irradiation ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Molecular Weights ◽  
Azobenzene Moiety ◽  
Azobenzene Group

A serious of triply-responsive poly(N,N-dimethylaminoethyl methacrylate) (PMAEMA) containing an azobenzene group as the terminal group were synthesized by atom transfer radical polymerization (ATRP). The ATRP process of DMAEMA was initiated by an azobenzene derivative substituted with a 2-bromoisobutyryl group (Azo-Br) using CuCl/Me6TREN as catalyst and the mixture of DMA and H2O (v/v = 3:1) as solvent. The molecular weights and their distributions of the resulting homopolymers (Azo-PDMAEMA) were characterized by gel permeation chromatography (GPC). The polymers are soluble in aqueous media and exhibit a lower critical solution temperature (LCST) that alternated reversibly in response to pH and photoisomerization of the terminal azobenzene moiety. It was found that the LCST increased as pH decreased in the range of testing. Under UV light irradiation, the trans-to-cis photoisomerization of the azobenzene moiety resulted in a higher LCST, while it recovered under visible light irradiation.

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