The variation of microfibril angle (MFA) of the S₂ layer in latewood tracheids was investigated in the root and stem woods of Chamaecyparis obtusa. MFA at breast height became stable near the 20th growth ring. The stable value of MFA was reached earlier with increasing height above the ground and at 8 m height MFA became stable near the 10th growth ring. However, there was little difference between stable values at different heights in the tree. MFA in root wood became stable near the 10th ring without regard to the distance from basal part to root tip. There was also little difference between stable values of MFA according to root wood diameter. Using the root wood at 20 cm from the basal part, which it is easy to take, prediction of MFA of mature wood in the stem was possible. There was a significant correlation at the 1% level between stable MFAs in root and stem. There was also a significant rank correlation at the 1% level. There was a significant correlation at the 0.1% level between MFA in the 18th to 20th ring of root wood and MFA of mature wood in the stem, but early prediction was difficult because the correlation coefficient decreased in young growth rings. On the other hand, it was suggested that it is possible to predict MFA of mature wood in the stem using the outer part of root wood larger than 40 mm in diameter.

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Mechanical properties, namely modulus of rupture (MOR), modulus of elasticity in bending (MOE) and impact bending strength, were measured with small clear test specimens of new and aged wood. The test specimens of keyaki (Zelkova serrata MAKINO) aged 255 years and akamatsu (Pinus densiflora SIEBOLD et ZUCCARINI) aged 115, 270 and 290 years were made of the same wood described in the previous report of this work. A Monte Carlo simulation was done to adjust the distribution shape of density of new wood to that of aged wood. Comparison of mechanical properties of aged and simulated new wood are summarized as follows : MOR and MOE decreased 16.3% and 14.8%, respectively, in aged keyaki wood, and increased 17.3%, and 10.8%, respectively in akamatsu wood aged 270 years, and 42.1%, and 26.8%, respectively, in akamatsu wood aged 290 years. In akamatsu wood aged 115 years the difference between new and aged wood was not significant. The impact bending strength decreased in both keyaki and akamatsu aged wood. The rates of decrease were 15.2% in keyaki wood, and 27.1% and 22.1%, respectively, in akamatsu wood aged 270 and 290 years. The ratio of the stress at proportional limit to the ultimate stress increased 14.1-31.9% in akamatsu aged wood. Judging from the results of the series of these studies, including the previous reports, it is seen that the aged akamatsu wood developed a tendency toward brittleness with the lapse of time though the aged wood showed higher values of strength (compression, static bending and shear) than new wood. This tendency led to a decrease of the length of the failure surface (tension), an increase in the proportional limit (compression and static bending) and a decrease in strength (tension and impact bending).

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Treating temperature, wood moisture content, and treating time are considered to be important factors for the set recovery of compressed wood when using a closed heating system. Hence we investigated the influence of these factors on the maximum pressure in a closed space and the integration of pressure in sapwood specimens of sugi (Cryptomeria japonica D. Don) heat-compressed at different temperatures and moisture contents. Also, we examined the relationships between the set recovery of compressed wood and the maximum pressure in the closed space or the integration of pressure. The results obtained were as follows :
1) At the same moisture content of wood specimens, the maximum pressure in the closed space hardly changed as the treating times increased at any of treating temperatures. 2) The integration of pressure increased at each treating temperature as the treating time increased. 3) At a treating temperature of 120°C, the maximum temperature in the closed space hardly changed, and the set recovery of compressed wood decreased as the moisture content of wood specimens increased. On the other hand, the maximum pressure in the closed space increased and the set recovery of compressed wood decreased at 160°C and 200°C as the moisture content of wood specimens increased. 4) When the integration of pressure in the closed space increased, the set recovery of compressed wood hardly changed at 120°C, whereas it greatly decreased at 160°C and 200°C.

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Phenol-formaldehyde resin (PF resin) solution was impregnated by a roller-press into Sugi (Cryptomeria japonica D. Don) sapwood, spruce (Picea spp.) heartwood, and Douglas-fir (Pseudotsuga menziesii Franco) heartwood, in the green or the air-dry condition and of various dimensions.
In case of sugi sawn timber, green specimens showed higher volume retention than air-dried specimens. At 45% compression, volume retention and the distribution of the solution in the longitudinal direction of 10 and 20 mm-thick specimens were almost the same. The distribution of volume retention in a cross section in the middle of those specimens was uniform in the 10 mm-thick specimens, but was concentrated in a marginal layer of the surface in the 20 mm-thick specimens. Volume retention and uniformity of distribution of the retention was enhanced with increasing of cyclic compression.
In the case of spruce and Douglas-fir sawn timber, volume retention of green specimens after cyclic compression showed a much greater increase than that of air-dried wood. This suggests that the green wood has a lower amount of pit aspiration (i.e., higher permeability of the aqueous solution and higher recovery of cell deformation) than that of air-dried wood.
In the case of sugi rotary veneer in the green condition, the time required for reaching the same volume retention as sawn timber was relatively short. The bending properties of LVL made of roller-pressed rotary veneer were not changed.

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In order to study the flow properties of wood powder-plastic mixture with a high proportion of wood powder, flow tests using capillaries of various sizes were performed. After starting to load, the mixture did not flow for a while but was only compressed. When the load increased to some extent and the mixture started to flow, a yield point of load was observed. As the mixture began to flow out continuously, flow resistance of the mixture and load generally balanced and a dynamic equilibrium state appeared. A high correlation was observed between yield load and dynamic equilibrium load. By using capillaries of various sizes, extrusion molded material with greatly differing bulk densities and surface characteristics was obtained. As for the surface characteristics, the same phenomenon as the defective molding called melt fracture in plastic molding was observed.

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Capillary flow tests were conducted on wood powder-plastic mixtures, and the analysis and evaluation of flow properties were performed based on a generally steady state. Apparent viscosity and slip velocity at the capillary wall were found analytically, and flow velocity distribution and details of the flow state were considered.
Consequently, it was inferred that the flow of the wood powder-plastic mixture was a composite of significant non-Newtonian flow and slip at the capillary wall. The proportion of flow attributed to the existence of slip at the capillary wall was sizeable among the entire flow. It was suggested that the rate would be large when the capillary diameter was small and the shear stress was high.

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In the consumer market, a specification for wood vinegar has not yet been established due to many different methods of production and kinds of raw material. As wood vinegar becomes more accepted in the consumer market, a standard specification is needed to guarantee safety and effectiveness. Currently there is no specification for quantifying the constituents of wood vinegar. This study was conducted to determine standard proportions and reproducibility of the constituents of distilled wood vinegar produced by a controlled distilling method. We examined a method of distillation which offered the possibility of establishing a stable specification for the proportions of the constituents. Based on this study we discussed the possibility of establishing an official quality specification for distilled wood vinegars. Five hundred and fifty-one samples of distilled wood vinegar were used in this study. Fifteen constituents were selected from all of the constituents of distilled wood vinegar. The proportion of constituents was investigated in order to determine the existence of a standard proportion and its reproducibility.
The following results were obtained.
1) The deviations of the constituent proportions of 13 compounds out of 15 showed a normal distribution.
2) A regular rule was found for the relationship between the change of concentration of acetic acid and that of the constituent proportion.
3) The deviation of the constituent proportion of each compound was investigated as to whether it was within the range of three standard deviations, which is generally recognized as a control limit. In 93.6% of the samples, all 15 compounds satisfied this range.
Furthermore, 15 compounds contained in wood vinegar before distillation were assayed, and their deviation was compared with that of distilled wood vinegar. As a result, the deviation of the compounds contained in distilled wood vinegar was about 1/4 of that in the undistilled wood vinegar. These results suggest the possibility of establishing an official specification for distilled wood vinegar, which is produced by a standard controlled distilling method, through the assay of each compound and its quality control in accordance with a quality specification.

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Tensile strength property of sugi wood (Cryptomeria japonica D. Don) compressed to various ratio was examined, and the relationship between the effect of compression volume and the morphological break was investigated for tensile strength. Focusing on the change in wood pore volume by compression, density, elastic modulus and tensile strength of the compressed wood were estimated by the law of mixture. The results showed that the density and elastic modulus obtained in this experiment could almost be estimated by the law of mixture, but this law of mixture could not be applied to tensile strength at the high compression ratio. The tensile strength of the compressed wood was almost the same for compression ratio of more than fifty percent, and did not correspond to the change of elastic modulus in tension, whereas the elastic modulus increased exponentially with the increase in compression volume. Observations of fracture morphological suggested that the lowering of the tensile strength in the cell wall, which was produced at exceeding the compression ratio of fifty percent, was coursed by the superposition action of the brittleness with the increase in compressive deformation of earlywood and latewood.

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