The effect of elevated temperature exposure on the fracture toughness of solid wood and structural wood composites

Fracture toughness of wood and wood composites has traditionally been characterized by a stress intensity factor, an initiation strain energy release rate (G _init) or a total energy to fracture (G _f). These parameters provide incomplete fracture characterization for these materials because the toughness changes as the crack propagates. Thus, for materials such as wood, oriented strand board (OSB), plywood and laminated veneer lumber (LVL), it is essential to characterize the fracture properties during crack propagation by measuring a full crack resistant or R curve. This study used energy methods during crack propagation to measure full R curves and then compared the fracture properties of wood and various wood-based composites such as, OSB, LVL and plywood. The effect of exposure to elevated temperature on fracture properties of these materials was also studied. The steady-state energy release rate (G _SS) of wood was lower than that of wood composites such as LVL, plywood and OSB. The resin in wood composites provides them with a higher fracture toughness compared to solid lumber. Depending upon the internal structure of the material, the mode of failure also varied. With exposure to elevated temperatures, G _SS for all materials decreased while the failure mode remained the same. The scatter associated with conventional bond strength tests, such as internal bond and bond classification tests, renders any statistical comparison using those tests difficult. In contrast, fracture tests with R curve analysis may provide an improved tool for characterization of bond quality in wood composites.     

Feasibility of supercritical carbon dioxide as a carrier solvent for preservative treatment of wood-based composites

 Supercritical carbon dioxide (SC-CO₂) was tested for its potential as a carrier solvent for preservative treatment of solid wood and wood-based composites. A preliminary trial showed that the treatability of solid wood varied with its original permeability and that the SC-CO₂ treatment was not promising for refractory timber species such a Larix leptolepis Gordon. In contrast, 3-iodo-2-propynyl butylcarbamate (IPBC)/SC-CO₂ treatment resulted in enhanced decay resistance without any detrimental physical or cosmetic damage in all structural-use wood-based composites tested: medium density fiberboard, hardwood plywood, softwood plywood, particleboard, and oriented strand board (OSB). Further trials under various treatment conditions [25°C/7.85 MPa (80 kgf/cm²), 35°C/7.85 MPa, 45°C/7.85 MPa, 35°C/11.77 MPa (120 kgf/cm²), and 45°C/11.77 MPa] indicated that although small changes in the weight and thickness of the treated materials were noted the strength properties were not adversely affected, except for a few cases of softwood plywood and oriented strand board. The results of this study clearly indicated that the treatment condition allowed SC-CO₂ to transport IPBC into wood-based composites, and the optimum treatment condition seemed to vary with the type of wood-based composite. Received: October 24, 2001 / Accepted: February 15, 2002 Part of this work was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001; and the 32nd Annual Meeting of the International Research Group on Wood Preservation, Nara, May 2001 Correspondence to:M. Muin     

Buttock temperature in a sedentary posture on plywood flooring of varying thickness over the ONDOL heating system

This study investigated the thermophysiological responses of healthy subjects that sat on the plywood covering of the ONDOL floor heating system. Environmental chambers were constructed for this study, wherein ambient temperature, and wall and ceiling surface temperature were controlled at 24°C, and relative humidity was 50%. The temperature of supply water (t _sw) flowing into the floor coil was altered from 15°C to 40°C at 5°C intervals. The floor covering materials used in this experiment were mortar and three types of plywood with thicknesses of 2.7, 7.5, and 12mm. The floor surface temperatures (t _f) and the skin temperatures of eight subjects were measured while they were sitting on the floor. Buttock temperature, in particular, was monitored. This experiment yielded the following results: (1) t _f was 17.0°–35.2°C on mortar finishing and 19.1°–30.2°C on 12-mm plywood covering; (2) the buttocks skin temperature increased with t _sw higher than 30°C on mortar finishing and for t _sw higher than 30°, 25°, and 20° on 2.7-, 7.5-, and 12-mm plywood finishing, respectively; (3) the differences of buttock temperature when t _sw was varied between 15° and 40°C were 11.4°C on mortar, 7.9°C on 2.7-mm plywood, 6.5°C on 7.5-mm plywood, and 5.0°C on 12-mm plywood; (4) using regression analysis, the neutral point temperature of buttocks was determined to be 32.8°C.Part of this report was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, Japan, March 2003     

Study of the release in water of chemicals used for wood preservation. Effect of wood dimensions

Summary Various chemicals are used for protecting wood samples against fungi, and some of them are released in water, leading to pollution of the water. The kinetics of pentachlorophenol release in water has here been studied by considering the diffusion through the wood along the three principal axes of diffusion. The experiments and the modelling of the process is successfully coupled. The numerical model takes into account the three principal diffusivities, the partition factor, the volumes of wood and water. The effect of wood sample length along the longitudinal axis of diffusion is studied especially, as longitudinal diffusivity is much higher than the other two principal diffusivities. The effects of the relative volumes of wood and water are also of considerable interest not only for the concentration of the chemical in water but also for the rate of release.Symbols C concentration of liquid (g/cm³)_ - C _c ,C _eq concentration of liquid on the surface, at equilibrium with the surrounding, respectively - C _i,j,k concentration of liquid in the wood at positioni, j, k - D diffusivity (cm²/s) - h coefficient of mass transfer on the surface (cm/s) - K partition factor - i, j, k integers characterizing the position in the wood - M _L ,M _R ,M _T dimensionless numbers - M _t ,M amount of chemical released after time t, after infinite time, respectively - t increment of time - L, R, T thickness of the slices taken in the wood for calculation - N _L ,N _R ,N _T number of slices taken in the wood - x, y, z coordinates - V _water volume of the surrounding water     

木质居室环境对哺乳动物一些生理指标的影响

用木材与木质材料组成的内装环境不但对居室的温度、湿度有调节作用,而且对动物体的生长、发育有一定的影响,这就是木材独有的环境学调节特性。近年来,中国台湾、日本和国内等学者相继开展了这方面的研究工作。王松永等(1997)、WangSongyong等(1994a ;1994b)对木质内装材料的房     

Carbon,Fossil Fuel,and Biodiversity Mitigation With Wood and Forests

Life-cycle analyses, energy analyses, and a range of utilization efficiencies were developed to determine the carbon dioxide (CO₂) and fossil fuel (FF) saved by various solid wood products, wood energy, and unharvested forests. Some products proved very efficient in CO₂ and FF savings, while others did not. Not considering forest regrowth after harvest or burning if not harvested, efficient products save much more CO₂ than the standing forest; but wood used only for energy generally saves slightly less. Avoided emissions (using wood in place of steel and concrete) contributes the most to CO₂ and FF savings compared to the product and wood energy contributions. Burning parts of the harvested logs that are not used for products creates an additional CO₂ and FF savings. Using wood substitutes could save 14 to 31% of global CO₂ emissions and 12 to 19% of global FF consumption by using 34 to 100% of the world’s sustainable wood growth. Maximizing forest CO₂ sequestration may not be compatible with biodiversity. More CO₂ can be sequestered synergistically in the products or wood energy and landscape together than in the unharvested landscape. Harvesting sustainably at an optimum stand age will sequester more carbon in the combined products, wood energy, and forest than harvesting sustainably at other ages.     

Effect of fire-retardant treatment on plywood pH and the relationship of pH to strength properties

Summary This paper investigates the relationship between wood pH and the strength properties of fire-retardant-treated (FRT) plywood, as it is affected by fire-retardant (FR) formulations, processing variables, and extended high temperature exposure conditions. The objectives of this study were to (1) identify the effect of post-treatment kiln-drying temperature, followed by high temperature exposure, on wood pH; (2) identify the effect of various mixtures of FR components, followed by high temperature exposure, on wood pH; (3) determine if treatment effects on strength and pH are affected by plywood thickness; and (4) quantify the relationship between changes in wood pH and strength loss and whether pH can be used as a predictor of strength loss. Results indicate that the differences in pH resulting from the initial redry temperature became insignificant after extended periods of high temperature exposure. All FR treatments studied caused large, rapid decreases in pH, with the most rapid decreases occurring with formulations containing phosphoric acid. Additions of borate compounds, especially disodium octaborate tetrahydrate (Timbor), produced a measurable buffering effect that slowed or lessened the decreases in pH. No differences in the effect of FRT on the wood pH-strength relationship were noted between the two plywood thicknesses evaluated. A strong relationship was noted between changes in pH of the plywood and reductions in strength and energy-related properties. These findings suggest that the pH of FRT plywood is a good indicator of its current condition and may have potential as a predictor of future strength loss as the plywood is subjected to elevated in-service temperatures. Received 8 January 1997     

A general equilibrium analysis of the economic aspects of the imposition of an export tax on the plywood sector in Indonesia

Computable general equilibrium (CGE) models are extensively used to simulate the economic impact of forest policies. In this study, we conduct a counterfactual analysis to assess the impact of an export tax ranging from 5 to 20% on the plywood sector to the Indonesian economy. The indonesian economy is aggregated into 5 sectors: 2 sectors are related to forest,i.e., (1) log, and (2) plywood. The other three sectors are not related to forest,i.e., (3) non-wood manufacturing, (4) agriculture, quarrying, and services, and (5) construction. The simulation results show that an export tax on the plywood processing sector is negatively correlated with real GDP and labor demand in log and plywood sectors, but is positively correlated with total labor demand, government revenue, income distribution, wood resources and social welfare. Reduction in labor demand by log and plywood sectors, due to a plywood export tax, can be absorbed in other sectors. The simulated policy of an export tax on plywood can reserve trees in production forests for future use.     

杨木胶合板沙发框架的制作工艺与结构性能分析

介绍杨木胶合板应用于沙发框架的制作工艺及结构性能。以杨木胶合板沙发框架实例,进行了角部接合抗弯刚度和整体耐久性的试验。结果表明:杨木胶合板替代实木应用于沙发框架的生产,能充分体现出板式零部件曲(直)边组合及叠加的造型优势,沙发框架整体具有稳定的力学性能。     

Energy wood resources availability and delivery cost in Northwest Russia

Availability of solid by-products from wood harvesting and mechanical wood processing was estimated as sources for energy production based on recent actual harvesting, sawmill, and plywood production in Northwest Russia at 30 million m³. Nearly 70% of the energy wood, 20 million m³, was from harvesting, consisting of non-industrial round wood, unused branches and tops, defective wood resulting from logging, and spruce stumps removed after final felling. Over 30%, 10 million m³, of the available volume was from sawmills and plywood mills, i.e. wood chips, sawdust, and bark. Due to current low utilization of energy wood for bioenergy in Northwest Russia, delivery cost of energy wood to the potential border-crossing points in Finland was analyzed for three means of transport: railways, roadways, and waterways. Nearly 28 million m³ of the energy wood could be transported by railways and 2 million m³ by roadways and waterways. The costs were lowest by roadways from the nearby border areas (10–15 €/m³ for wood processing by-products and 16–22 €/m³ for forest chips). The costs by railways varied from 12 to 27 €/m³ on shorter distances to 47–58 €/m³ on longer distances. Waterway transportation was the most expensive, about 28–48 €/m³. It should be emphasized that we have estimated availability and delivery costs of energy wood, not prices which are defined by the market based on supply and demand.     

Extraction and decomposition of hiba wood into valuable chemicals using stepwise temperature supercritical carbon dioxide treatment

Hiba (Thujopsis dolabrata) wood was treated with supercritical carbon dioxide (scCO₂) at stepwise temperature increments from 50° to 400°C continuously so that extractives (dichloromethane-soluble and -insoluble phases) and solid residues were obtained. The yield of extractives from hiba wood increased with increasing extraction temperature. The volatile compounds in the dichloromethane-soluble phase from scCO₂ extraction at 50°C contained only terpenoids. However, the volatile compounds in the dichloromethane-soluble phase from scCO₂ extraction at 300°C not only contained terpenoids but also phenols, furans, hydrocarbons, and organic acids. The yield of β-thujaplicin, which is a useful compound in hiba wood, increased with increasing extraction temperature from 50°C to 300°C; the optimal conditions for extracting β-thujaplicin were 300°C and 19.61 MPa. Further study of degradated compounds from the cellulosic and lignic materials of hiba wood after stepwise high-temperature scCO₂ treatment above 300°C may provide clues to its efficient use.     

Interception of photosynthetic photon flux density in a mangrove stand of <Emphasis Type="Italic">Kandelia candel</Emphasis> (L.) Druce

The canopy structure and interception of photosynthetic photon flux density (PPFD) in a 10-year-old Kandelia candel (L.) Druce stand were investigated before and after artificial defoliation. Leaf and wood areas for different layers were measured through area–weight relationships of subsamples. PPFD was measured at specified heights before and after leaf clipping. The leaf area index (LAI) and wood area index (WAI) were 4.501m²m^–2 and 1.412m²m^–2, respectively. There was a strong linear relationship between the cumulative wood area © and leaf area (F) densities from the top down to a given depth of the canopy, C = aF (r ² = 0.950), with a proportional constant a of 0.096 ± 0.008 (mean ± SE). The PPFD relative to that above the canopy (relative PPFD; I _R) at a given depth of the canopy was assumed to be given by the equation I _R = e^–(KCC+KFF ) = e^–KF , where the apparent light extinction coefficient K (= K _F + aK _C , where K _F and K _C are respectively the light extinction coefficient of leaves and woody organs) was calculated to be 0.502 ± 0.041 (mean ± SE) m^–2m² before leaf clipping. After leaf clipping, I _RC = e^–KCC is satisfied. As a result, the value of K _C was estimated to be 0.785 ± 0.046 (mean ± SE) m^–2m². The light extinction coefficient of leaves K _F was calculated to be 0.427m^–2m² using the indirect method, K _F = K – aK _C, and 0.432 ± 0.026 (mean ± SE) m^–2m² using the direct method, I _R/I _RC = e^–KFF . Of the total PPFD intercepted by the canopy, the fraction K _F/K due to leaves alone was estimated to be 85.0%–86.1% and the rest was contributed by woody organs.     

Improvement of wood properties by urea-formaldehyde resin and nano-SiO2

In order to improve wood properties of triploid clones of Populus tomentosa, urea-formaldehyde (UF) resin was compounded with nano-SiO₂, coupling agents and flame retardants in different ways to prepare five kinds of modifiers. The poplar wood samples were impregnated with the modifiers and heated to prepare UF-SiO₂-wood composites. The antiswelling efficiency, resistance of water absorption, oxygen index and hardness of the composites were measured. Results show that all of the modifiers reduced water absorption of poplar wood and enhanced flame resistance and hardness. Nano-SiO₂ showed a marked effect in improving the hardness of wood. In addition, all of the modifiers, except UF-C-SiO₂-polymer, improved the dimensional stability of poplar wood. The UF resin and nano-SiO₂ compound improved general properties of poplar wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(2): 123–128 [译自: 北京林业大学学报]     

Methods for the determination of wood properties,Kraft pulp yield and wood fibre dimensions on small wood samples.

A trial set-up with methods for sampling, treatment and analysis of small wood chips are presented in this paper, to determine important wood and fibre properties, like basic density, dry density, volume swelling of wood, Kraft pulp yield, fibre length, fibre coarseness, fibre width, lumen width and fibre wall thickness. The required time for one sample is about 1.5 man-hour, but this requires relatively larger series and trained personnel. Acceptable measurement accuracy is achieved when the volume of the wood sample is at least 1.5 ml, except that of wood volume swelling. To gain acceptable measurement accuracy for volume swelling, the wood volume should be increased to at least 3 ml, and preferably more than 5–6 ml per sample. The level of pulp yield and wood density do not show a significant effect on the measurement accuracy for fibre cross-section dimensions. Fibre coarseness, on the other hand, has a significant influence on these accuracies. A double measurement of fibre coarseness will improve the accuracy to an acceptable level. The method presented here may, together with information about trees and growth locations, form the basis for greater insight into the mechanisms involved in development of wood and fibre properties in trees, which in turn may provide better control and utilisation of wood for pulp and paper production.Abbreviations CWD cell wall density in dry wood=1500 kg/m³ - Ww dry weight of wood (kg) - Vmax green (wet) volume of wood (m³) - Vmin dry volume of wood (m³) - BD basic wood density (kg/m³) - DD dry wood density (kg/m³) - VS maximum volume swelling of wood (%) - Wp dry weight of pulp (kg) - PY pulp yield (%) - C fibre coarseness, the average weight of a unit length of fibre (g/m) - CL average chip length (mm) - CWT average cell wall thickness (m) - FW average fibre width (m) - l average native fibre length in solid wood - L chip length - lc average fibre length in wood chip (mm) - Lc length-weighted fibre length in wood chip (mm) - lw native average fibre length in wood (mm) - Lw native length-weighted fibre length in wood (mm) - LW average lumen width (m) - llw average native fibre length, length weighted, in wood - X average fibre length in chip - Xlw average fibre length, length weighted, in chip     

Study of the release in water of a chemical used for preservation of wood. Effect of the dimensions of the wood

Summary Various chemicals are used for protecting wood samples against fungi, and some of them are released in water, leading to pollution of the water. The kinetics of release of pentachlorophenol in water has here been studied, by considering the diffusion through the wood along the three principal axes of diffusion. The experiments and the modelling of the process is successfully coupled. The numerical model takes the three principal diffusivities, the partition factor, the volumes of wood and water into account. The effect of the length of the wood sample taken along the longitudinal axis of diffusion is especially studied, as the longitudinal diffusivity is much higher than the other two principal diffusivities. The effect of the relative volumes of wood and water is also of considerable interest not only for the concentration of the chemical in water but also for the rate of release.Symbols C concentration of liquid (g/cm³) - C_s, C_eq,t concentration of liquid on the surface, at equilibrium with the surrounding, respectively - C_i,j,k concentration of liquid in the wood at position (i, j, k) - D diffusivity (cm²/s) - h coefficient of mass transfer on the surface (cm/s) - i, j, k integers characterizing the position in the wood - K partition factor - L, R, T dimensions of the parallelepipedic wood sample - Mini amount of chemical contained in the wood at the beginning of the desorption - M_L, M_R, M_T dimensionless numbers - M_t, M amount of chemical released up to time t, up to infinite time, respectively - N half-number of slices taken in the wood parallelepiped along each dimension - V_water volume of the surrounding water - x, y, z coordinates - L, R, T thickness of the slices taken in the wood for calculation - t increment of time     

Financial feasibility of increasing carbon sequestration in harvested wood products in Mississippi

Longer forest rotation ages can potentially increase accumulation of carbon in harvested wood products due to a larger proportion of sawlogs that can be used for manufacturing durable wood products such as lumber and plywood. This study quantified amounts of carbon accumulated in wood products harvested from loblolly pine (Pinus taeda L.) stands grown in Mississippi by extending rotation ages traditionally used to manage these stands for timber. The financial viability of this approach was examined based on carbon payments received by landowners for sequestering carbon in standing trees and harvested wood products. Results indicated a potential to increase carbon accumulated in wood products by 16.11 metric tons (t) of carbon dioxide equivalent (CO₂e) per hectare (ha) for a rotation increase of 5 years and 67.07 tCO₂e/ha for a rotation increase of 65 years. Carbon prices of $50/tCO₂e and $110/tCO₂e would be required to provide a sufficient incentive to forest landowners to extend rotations by 5 and 10 years, respectively. With 2.8 million ha of loblolly pine stands in Mississippi, this translates to a possible increase in wood products carbon of 45 million tCO₂e and 80 million tCO₂e for harvest ages increased by 5 and 10 years, respectively. Higher carbon prices lengthened rotation ages modestly due to low present values of carbon accumulated with long rotations.     

HTST hydrolysis of wood: Modelling of the kinetics and projections on reactor configuration

Summary We present experimental data on hydrolysis of wood in high temperature short residence time (HTST) and low acid concentration conditions. Effects of temperature, acid concentration, particle size and liquid/solid ratio are discussed. A kinetic model is proposed which accounts for effects of temperature and acid concentration. This kinetic model is used to predict performance of a twin-screw extruder as a hydrolyser which consists of ideal mixed flow or plug flow reactor units in series.Symbols A Acid concentration in liquid phase - A Acid concentration in solid phase - A₀ Initial mass of sulphuric acid, g - C Cellulose content of solid phase, % - d Diameter of wood particles, m - E₁ Activation energy of cellulose hydrolysis, cal. mol^-1 - E₂ Activation energy of glucose degradation, cal. mol^-1 - F Objective function, refers to Eq. (5) - G Glucose yield - G_e Glucose yield at equilibrium - G_{i, exp} Experimental glucose yield (Eq. (5)) - G_{i, th} Calculated glucose yield (Eq. (5)) - G_max Maximum glucose yield - k^* Parameter defined by Eq. (9) - k₁ Rate constant of cellulose hydrolysis, s^-1 - k₂ Rate constant of glucose degradation, s^-1 - k ₁ ^* Apparent rate constant of cellulose hydrolysis, s^-1 - k ₂ ^* Apparent rate constant of glucose degradation, s^-1 - k₁₀ Pre-exponential factor of constant k₁, s^-1 - k₂₀ Pre-exponential factor of constant k₂, s^-1 - K Parameter defined in Table 3 - m Constant - m_g Mass of glucose produced, g - M₀ Initial mass of wood, g - M Mass of saturated steam delivered, g - M Mass of saturated steam delivered after 120 s of reaction time, g - m₀ Initial mass of water, g - n Constant - N Number of reactor units - q_i Volume flow rate in reactor units, m³ · s^-1 - r_g Conversion rate of glucose, s^-1 - R Ideal gas constant, 1.987 cal · mol^-1 K^-1 - t Reaction time, s - T Temperature, K - V_i Volume of reactor units, m³ - W Water content of wood sample, % - X, X Parameters defined in Table 3 - Y, Z Parameters defined in Table 3 - Constant defined in Eq. (4), s^-1 - v Number of experimental points (Eq. (5)) - _i Residence time in plug flow unit, s - _i Residence time in mixed flow unit, s     

Pyrolytic characteristics of burning residue of fire-retardant wood

In order to investigate the pyrolytic characteristics of the burning residue of fire-retardant wood, a multifunctional fire-resistance test oven aimed at simulating the course of a fire was used to burn fire-retardant wood and untreated wood. Samples at different distances from the combustion surface were obtained and a thermogravimetric analysis (TG) was applied to test the prrolytic process of the burning residue in an atmosphere of nitrogen. The results showed that: 1) there was little difference between fire-retardant wood and its residue in the initial temperature of thermal degradation. The initial temperature of thermal degradation of the combustion layer in untreated wood was higher than that in the no burning wood sample; 2) the temperature of the flame retardant in fire-retardant wood was 200°C in the differential thermogravimetry (DTG). The peak belonging to the flame retardant tended to dissipate during the time of burning; 3) for the burning residue of fire-retardant wood, the peak belonging to hemicellulose near 230°C in the DTG disappeared and there was a gentle shoulder from 210 to 240°C; 4) the temperature of the main peaks of the fire-retardant wood and its burning residue in DTG was 100°C lower than that of the untreated wood and its burning residue. The rate of weight loss also decreased sharply; 5) the residual weight of fire-retardant wood at 600°C clearly increased compared with that of untreated wood. Residual weight of the burning residue increased markedly as the heating temperature increased when burning; 6) there was a considerable difference with respect to the thermal degradation temperature of the no burning sample and the burning residue between fire-retardant wood and untreated wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(3): 133–138 [译自: 北京林业大学学报]     

Index selection for growth and construction wood properties in Pinus elliottii open-pollinated families in southern China

The initial introduction of Pinus elliottii (PEE) to China occurred in the 1930s, and the planting of this conifer species has now attained close to 3 million ha in the subtropical zone of southern China. A large-scale genetic improvement program for PEE was implemented in southern China to produce fast-growing trees with high wood quality to address the severe shortage of timber production over the last two decades. In this paper, selection for stem volume, basic wood density (DEN) and modulus of elasticity (MOE) was based on the Smith–Hazel index, and a total of approximately 2 000 individual trees from 158 PEE open-pollinated families were selected at 22 years of age. The DEN and MOE for each tree were determined by non-destructive evaluation techniques using the Pilodyn and Hitman Director ST300® acoustic velocity device. The heritabilities and genetic and phenotypic correlations for the traits that were measured were estimated using the residual maximum likelihood approach in the flexible mixed modelling program ASReml-R. The results showed that the heritability estimates for the wood properties were between 0.292 and 0.309, and the heritabilities of the growth traits ranged from 0.129 to 0.216. The genetic correlation between the DEN_P and acoustic velocity (V?) with MOE_P was 0.45 and 0.95, respectively. An indirect selection based on V was observed to be highly effective for determination of MOE. It indicated that V can be integrated into tree improvement programs as a useful index of MOE by ranking candidate families or individuals within the selection population. The genetic correlations between the growth traits and wood properties were not significant. By contrast, the phenotypic correlations between them were significantly positive, but the correlation coefficients were very low. The appropriate selection index (I₄), which placed 10 times as much weight on DEN and MOE as the equal emphsis method, was determined as the appropriate selection index.     

Properties of the cell wall constituents in relation to the longitudinal elasticity of wood

This study examined the origin of the moisture dependency of the longitudinal Youngs modulus of wood (E _L ) in relation to the microfibril angle (MFA) of the S2 layer of the secondary wall. Microtomed early wood specimen of sugi (Cryptomeria japonica D.Don) were used for the experiment. The following was revealed: