Fungal decomposition of wood severely affects the soundness of timber constructions. The diagnosis of wood decay requires direct observations or sampling by skilled experts. Wood decay often occurs ...in obscure spaces, including the enclosed inner spaces of walls or under the floor. In this study, we examined the ability of machine olfaction to detect odors of fungi grown on common construction softwoods to provide a novel diagnostic method for wood construction soundness. The combination of a simple device equipped with semiconductor gas sensors (gas sensor array) and multivariate analysis discriminated a fungi-related odor from control odor without instrumental analysis (e.g., gas chromatography). This method is often referred to as machine olfaction or electronic nose. We measured the odor of wood test pieces that were infected with
Fomitopsis palustris
or
Trametes versicolor
and sound test pieces using a gas sensor array. The sensor responses of the specimens showed different patterns between the inoculated and control samples. Each specimen class formed independent groups in a principal component score plot, almost regardless of wood species, fungal species, or cultivation period. This method provides a new decay diagnosis method that is cost-effective and easy to operate.
The effects of copper monoethanolamine (CuA) treatment of wood surfaces on the surface weathering and durability of a semitransparent penetrating stain were compared with those of chromic acid (CrA) ...treatment which is known as a photoprotective primer, using artificial weathering trials. Chemical changes in chemically treated and untreated wood surfaces during artificial weathering were investigated using Fourier transform infrared (FTIR) spectroscopy. Surface roughness, water contact angle measurements and scanning electron microscopy observations were performed to assess stain durability. Results of FTIR analyses indicated that lignin losses following CuA and CrA treatment were less than those of the untreated wood surfaces during the initial stage of artificial weathering. CuA pretreatment prior to staining also retarded the increase in the average surface roughness compared with that observed for the CrA-pretreated surface and untreated control (only stained) during artificial weathering. Furthermore, CuA pretreatment retarded the decrease in the contact angle compared with that observed for the untreated control, although the use of a highly concentrated CuA solution led to a decrease in the water repellency of the stained wood surface. These results indicated that CuA solution could be used for the pretreatment of wood surfaces to enhance the durability of semitransparent penetrating stains, as long as excessive CuA concentrations are avoided.
The objective of this study is to investigate the effect of surface processing on the natural weathering performance of coated wood. The surface processing of four different roughness categories ...(processed by planing, sawing, wire-brushing, and sanding) was used for treating wood substrates (Sugi: Cryptomeria japonica D. Don). A preservative semi-transparent coating was applied on the wood substrates and exposed to natural weathering for 7 years. The coated wood surfaces were assessed using color difference (JIS K 5600-4-6), water repellency index, and visual assessment (JIS K 5600-8-4 and JIS K 5600-8-5). The difference in surface processing influenced the coating weights and the degradation speed of the coatings. The water repellency index of rough-sawn specimens maintained more than 80 % up to 5 years of natural exposure and the specimens exhibited lower flaking throughout 7 years of exposure, which has higher performance than other processing. The results indicated rough-sawn lumber was effective surface processing to improve natural weathering performance of preservative semi-transparent coatings.
Utilization of rapidly growing trees, such as eucalypts, for high-yield mechanical pulps is limited by low brightness owing to high contents of alkali and neutral extractives. Wood supply problems ...have developed in many areas of the world and new sources of high-yield pulp are needed. Ten Eucalyptus globulus trees were selected from two plantation sites to evaluate suitability as raw material for high-quality and high-yield pulp. Chemithermomechanical pulp (CTMP) was prepared from tree chips pretreated with sodium sulfite prior to refining. Characteristics of the CTMP were correlated with chemical and physical properties of the wood. There was a linear relationship between the content of alcohol-benzene extractives in wood and CTMP brightness. Klason lignin content in wood was inversely correlated with pulp sheet density, which is an important characteristic affecting the physical properties of pulp. The content of alkali extractives were inversely correlated with pulp yields. Color reversion was tested by exposing CTMP sheets to heat and light. Heat-induced yellowing of CTMP was of a low level and satisfied requirements for printing paper. The rate of yellowing was inversely associated with extractives and can be reduced by antioxidants.
The purpose of this study was to investigate the freeze-thaw resistance of water-borne wood coatings. The resistance of karamatsu heartwood specimens finished with 8 waterborne(WB)and 3 ...solvent-borne(SB)wood coatings was assessed by a 24-month natural weathering test, and a freeze-thaw cycle test. The natural weathering test was started in winter in order to examine the resistance. Water permeability of coated surface and coating film flexibility by a coating bending test were also examined to determine their relationships to the resistance. The percentage areas of coating flaking of one WB and SB coatings were over 80% after 3 months of natural exposure and 30 cycles of freezingthawing. These coatings showed high water permeability and low flexibility. The results showed that some coatings were damaged by the freezing and thawing, regardless of the type of coating(water- or solvent-borne), and suggested that flexible coatings might be less susceptible to freezing and thawing.
PDF
