Takeshi Furuno

The modification of wood by treatment with low molecular weight phenol-formaldehyde resin: a properties enhancement with neutralized phenolic-resin and resin penetration into wood cell walls

To enhance dimensional stability and biological properties, low molecular weight phenolic resins of a conventional alkaline type and neutralized type were impregnated into Japanese cedar wood (Cryptomeria japonica D. Don) and heat-cured. The treatment with the neutralized type resin retained the original wood color, whereas the alkaline treatment changed the color of wood to red-brown. The concentrations of the resin solutions and the weight gains due to the resin loading of wood after treatment were highly correlated, and the target resin loading could be assessed from the solution concentration. A high dimensional stability of 60% antiswelling efficiency was attained when both types of resins were impregnated at about 30% resin loading and no significant difference was recognized between the two. To suppress decay attack from brown-rot and white-rot fungi, 15% and 10% resin loading due to treatment was required for the neutralized and alkaline types of phenolic resins, respectively. The penetration of resin into wood cell walls was investigated by means of light microscopy, Scanning Electron Microscopy (SEM), and Electron Probe X-ray Microanalysis (EPMA). A m-Bromophenol-formaldehyde resin of three levels of an average molecular weight was used to detect the presence of resin by bromine signals. The phenolic resins with low and medium molecular weights (290 and 470) were shown to penetrate into the cell walls the furthest, thereby contributing to the enhancement of dimensional stability and decay resistance in the resin-impregnated wood. Also, for phenolic resin with a high molecular weight (820), only the resin components of low molecular weight appeared to be present in the walls, making very little contribution to the dimensional stability.

Effect of bamboo vinegar on regulation of germination and radicle growth of seed plants

Abstract Two kinds of bamboo vinegar from madake bamboo (Phyllostachys bambusoides) and moso bamboo (Phyllostachys pubescens) were prepared to analyze their components by gas chromatography (GC). The original vinegar, distilled vinegar, ether-extracted vinegar, and three fractions including acidic, neutral, and phenolic fractions separated from ether-extracted vinegar were diluted with distilled water 102 to 107 times. These diluted vinegar solutions were used to investigate the effect of bamboo vinegar on the germination and radicle growth of seed plants. High concentrations of all kinds of treated bamboo vinegars (e.g., 102 of original vinegar and 103 of ether-extracted vinegar) showed strong inhibition against germination of the seeds. However, an appropriate dilution of bamboo vinegar showed an obvious promotional effect on germination and radicle growth for the four kinds of tested seeds (lettuce, watercress, honewort, chrysanthemum).

Chemical modification of wood by anhydrides without solvents or catalysts.

Acetylated, propionylated, butyrylated, isobutyrylated, and hexanoylated woods were prepared at several temperatures. The reaction rate, dimensional stability, and changes in the ratios of specific gravity and dimensions in the tangential and radial directions were estimated. The reaction rate of propionylation was slow at temperatures under 90°C but increased with the temperature. The butyrylated, isobutyrylated, and hexanoylated woods showed little or no weight percent gain (WPG) and little or no antiswelling efficiency (ASE) below 110°C even for 24h, but they achieved significant WPG and ASE values at 140°C with a longer reaction time. The acetylated, propionylated, and butyrylated woods showed almost the same values for dimensional stabilization efficiency based on WPG (DSE). The specific gravity and dimensions ratios for acetylated, propionylated, and butyrylated woods compared to those of untreated wood increased with an increase in WPG.

Effect of bamboo vinegar on regulation of germination and radicle growth of seed plants II: composition of moso bamboo vinegar at different collection temperature and its effects

Moso bamboo vinegar was treated with extractive and separation methods. The acidic, neutral, and phenolic fractions separated from ether-extracted vinegar were analyzed by gas chromatography and gas chromatography-mass spectrometry to identify the major components in moso bamboo vinegar. The compositions of eight moso vinegar fractions collected over different temperature ranges from 100°C to 480°C were also analyzed and their effects on regulation of germination and growth were studied by bioassay with seeds of watercress and chrysanthemum. The results showed that moso bamboo vinegar fractions with collection temperatures up to 250°C promoted radicle and hypocotyl growth and this effect became larger with increasing collection temperature for chrysanthemum. Moso bamboo vinegar collected from 250°C to 400°C had a strong inhibition on germination and radicle growth for both seed types when tested at 103 dilution.

Combinations of wood and silicate Part 6. Biological resistances of wood-mineral composites using water glass-boron compound system

SummaryWood-mineral composites were made by introducing inorganic substances into wood using the water glass (sodium silicate)-boron compound system (double treatment). Composites were also prepared with boron compounds alone (single treatment), and biological resistances of the two types of composites were evaluated and compared.After the leaching procedure, the composites using the water glass-boron compound system showed generally excellent termite resistances with the negligible weight losses of specimens and high mortalities of workers and soldiers. On the contrary, the single treatment and the double treatment using the reactants of non-boron compounds showed slight or little resistances against termite attacks, accounting for the high leachability of the inorganic substances formed in wood and/or low effectiveness of the chemicals.Also, the water glass-boron compound system was found to enhance greatly the decay resistances if water-soluble inorganic substances were fully removed out from the specimens. The formation of insoluble inorganic substances in the water glass-boron compound system proved to contribute much to the enhancement of biological resistances.

Formaldehyde emission from wood products: relationship between the values by the Chamber method and those by the Desiccator test

The formaldehyde off-gassing properties of various wood products were evaluated under environment conditions that simulate conditions of mobile home. The formaldehyde concentrations observed in the chamber were correlated to the 24-h desiccator formaldehyde potentials. It was found that 24-h desiccator values did correlate to formaldehyde levels in the chamber at a given temperature, relative humidity, air change rate, and sample loading. The 24-h desiccator method correlated to each other for a given wood product. Formaldehyde levels of wood products tested in combination reflected the levels of the highest single emitter. Formaldehyde concentrations from combinations of particleboards and plywood panels may be predicted from their single chamber K factor using the modified Hoetjer equation. Double loading of a single wood product did not double the chamber concentration at the low air change rate and sample loading. Finally, the formaldehyde concentrations observed in the chamber under conditions that simulated mobile loadings of wood product, air change rate, temperature, and humidity relate to real wood formaldehyde levels.

Properties of gypsum particleboard reinforced with polypropylene fibers

This paper details the influence of the length and content of polypropylene (PP) fibers on the physical and mechanical properties of gypsum particleboard (GPB). The length and amount of PP fibers added had a significant effect on the internal bond strength (IB) and the modulus of rupture (MOR) of GPB. The highest IB value was shown at 9 mm length and 9% content of PP fibers. The MOR was highest when the board was made with PP of 12 mm fiber length and 12% content. Suitable contents of PP fibers were advantageous in that they reinforced the properties of GPB so it achieved high performance. In contrast, a high content of PP fibers reduced the IB, MOR, and modulus of elasticity (MOE) of GPB. The thickness swelling was reduced with an increase in PP length and content. It was concluded that the combination of 12 mm length and 12% content or 3mm length and 9% content was optimum for producing good performance of GPB.

Study on Gypsum-Bonded Particleboard Reinforced with Jute Fibres

Summary This paper deals with the influence of length and content (based on a percentage of wood particles) of jute fibers on the physical and mechanical properties of gypsum-bonded particleboard (GPB). The length and amount of jute fibers had a significant effect on the internal bond strength (IB) and the modulus of rupture (MOR) of GPB. The addition of jute fibers did not obviously influence the modulus of elasticity (MOE), the thickness swelling (TS) or water absorption (WA). The values of IB were prominently high at the 3 mm length and 9–12% contents of jute fibers. The highest value of MOR was attained when the board was made with fibers 12 mm in length and a fiber content of 15%. The optimal amount of jute fibers reinforced the mechanical properties of GPB to achieve high performance. However, too much jute fiber reduced the IB, MOR (except for 12 mm length), and MOE of GPB. The values of TS and WA decreased gradually with an increase in the fiber content for all fiber lengths. In addition, the GPB gave very low weight loss on exposure to wood-decaying fungi of both Tyromyces palustris (TYP) and Coriolus versicolor (COV) as compared with untreated wood. It was concluded that the combination of 3 mm length and 9–12% content or 12 mm length and 15% content of jute fibers was the optimum for producing good performance of

Leachability, decay, and termite resistance of wood treated with metaborates

The formation of insoluble metaborates in wood was investigated by impregnating the wood with borax and metallic salts, after which their properties (e.g., leachability in running water and biological resistance) were evaluated. The solubility of three metaborates in acidic solutions was also evaluated. Double-diffusion treatment was carried out to form the precipitates of metaborates in sapwood specimens of Japanese cedar (Cryptomeria japonica) at room temperature. Water-saturated wood specimens were first impregnated by a saturated borax solution and then diffuse-penetrated with Zn2+, Ca2+, or Pb2+ solution. The precipitates of the three metaborates in the wood proved to be insoluble or hardly soluble in water by the leaching test. With the decay test using a brown-rot fungus (Fomitopsis palustris) and a white-rot fungus (Trametes versicolor) and with the termite test using a virulent subterranean termite (Coptotermes formosanus), the metaborate-treated woods showed generally good decay and termite resistance with negligible mass loss of the specimens. Particularly, the lead metaborate formed in the wood provided superb biological resistance against decay and termite attacks. In addition, the precipitates of these metaborates were found to be soluble in acidic solution, suggesting a way to remove these chemicals from wood when disposing of waste materials.

The fractal estimation of wood color variation by the triangular prism surface area method

Abstract Color variations of the surfaces of fifteen wood species were characterized by fractal dimension of the triangular prism surface area method. Softwood and hardwood indicated apparently different in the mean fractal dimensions of red and green colors. Red color behaved steadier in softwood than in hardwood and green color varied comparatively stronger in hardwood than in softwood. No evident differences between softwood and hardwood were found in the variation of blue color of all the specimens. Following the low-to-high value order of the mean fractal dimensions, three types of combination of red (R), green (G) and blue (B) colors were found: RGB, RBG and BGR. There also existed six types of fractal dimension distribution; namely, plane, included plane, concave, convex, zigzag, and hilly distributions. Fractal dimensions across the grain changed greatly whereas those along the grain became relatively steady. The characteristic difference of color variation was defined for each species, which was inferred to characterize its own unique appearance of surface color. For color matching of wood parts, fractal dimension quantitatively furnishes essential information of color variation in local and overall features. Such evaluation can be efficiently carried out with few measurements along the grain and by detecting a single color (red, green or blue) only.