Cellulose is a major chemical component of woody biomass. Accordingly, better understanding of the chemistry involved in cellulose pyrolysis is important for improving the conversion technologies based on woody biomass pyrolysis, which include fast pyrolysis, gasification, carbonization and torrefaction for production of bio-fuels, bio-chemicals and bio-materials. Such information would also be suggestive of effective treatment of wood and other cellulosic materials at high temperatures, including wood drying and production of cellulose-plastics composites. Cellulose decomposition occurs rapidly in the temperature range > 300°C, whereas some relevant reactions occur even at temperatures lower than 200°C. In this review, cellulose pyrolysis is discussed, focusing on the reactions and molecular mechanisms.

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Taking Hiwada bark for roof plates from Japanese cypress, (Hinoki, Chamaecyparis obtusa), is sustainable because the cambium zone is carefully left without damage by traditional technicians (Motokawa-shi). This study aimed to clarify whether bark decortication for Hiwada changes the mechanical properties of the wood of the decorticated tree, focusing on changes in Young's modulus and cellulose microfibril angle (MFA) in the secondary cell wall of tracheids. Several pairs of Japanese cypress trees, planted in similar environmental conditions and aged > 69 years, were carefully selected. One tree of each pair was decorticated, and the other (control) was left without any treatment. In order to remove the variability at each cell level, serial sections having the same mother cells were collected by sampling along the radial direction. The Young's modulus and MFA of the specimens were tested and the measured values were averaged for each annual ring. Then, five to nine annual rings each before and after decortication, and their changes over time were compared to the control, and the impact of decortication itself was discussed and investigated. In order to remove individual variability, we suggested the value of v=(Xn-Xn_-1)/Σ|(Xn-Xn_-1)|, where Xn and Xn_-1 are the measured values of current and previous years, respectively. The value Xn-Xn_-1 represents the level of change in the year. Individual variability was removed by dividing by Σ|(Xn-Xn_-1)|. The difference in v of the decorticated and untreated trees was plotted for each annual ring, but a conspicuous change was absent for both Young's modulus and MFA. These findings indicate that the xylem part was not affected by Hiwada decortication any more than by the usual climate impact. The Hiwada decortication by master technicians therefore does not affect the wood properties.

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To evaluate the effect of tightening velocity on the torque coefficient of timber jointing with bolts, the tightening tests were carried out for 4 conifers used in wooden buildings under 5 tightening velocities. As a result, it was found that the torque coefficient decreased as the tightening velocity increased. Furthermore, it would appear that the difference in torque coefficients among species also decreases under 20 rpm. In addition, the torque coefficient of timber jointing with bolts had the same properties as joints without timber. Therefore, it seemed that the torque coefficient of bolted timber joints can be considered the same as the torque coefficient of joints without timber. The spread of torque coefficients might diminish when the tightening velocity was set at 20 rpm.

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Simulating a nail-joint of wood-based panel onto lumber, a new test method of lateral nail resistance (LNR) was devised. The test jig is a one-plane-shear (OPS) type that does not induce a compulsory pull-through of the nail head. The LNR of particleboard with a thickness of 12 and 15 mm was tested to compare this method and the two-plane-shear (TPS) type of test according to ASTM D 1037. The LNR by the OPS type was found to be forty to sixty percent of that by the TPS type. The rate of increase of LNR due to increase of nail edge distance (de) of nail from 12 up to 24 mm was lower in the OPS type than in the TPS type. There was no significant difference of LNR tested at two nail positions, at the center of the specimen's width and at a corner, for both the OPS and TPS types in the range of de from 12 to 24 mm. The retention of LNR after two types of accelerated aging that combined water-soaking and drying was found to be two to ten percent higher in the OPS type than in the TPS type.

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