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1.
The effect of tool angles on the shapes of chips generated by parallel-to-grain and end-grain milling was explored for China
fir and maple under fixed spindle and feed speeds and cutting depth. The milling path was up-milling by straight router-bits
with a diameter of 12 mm. The chip shapes could be distinguished as five types: spiral, splinter, flow, thin, and granules
or powder. The flow and thin chips were generated most often (on a weight percentage basis) for all tool angles investigated
for parallel-to-grain and end-grain milling of China fir and maple. More granule chips were produced with parallel-to-grain
milling than with end-grain milling for both woods. The measured chip thickness (t′) was thicker than the calculated thickness (t
max). Thicker and longer maple chips were produced by end-grain milling than by parallel-to-grain milling. The tool geometries
of 40°/15° (sharpness of the angle–rake angle), 50°/15°, and 60°/15° for China fir and 40°/25°, 50°/5°, and 60°/5° for maple
produced relatively more flow chips with parallel-to-grain milling. Furthermore, the tool geometries of 40°/5°, 50°/15° and
60°/25° produced more flow chips (weight percentage) by end-grain milling of China fir and maple.
Received: May 23, 2001 / Accepted: June 28, 2002
Acknowledgment This study was supported by a grant from the National Council of Science, Taiwan (NSC89-2313-B-415-011). 相似文献
2.
Subyakto Bambang Subiyanto Toshimitsu Hata Shuichi Kawai 《Journal of Wood Science》2003,49(3):241-247
Some tropical fast-growing woods were converted to edge-jointed lumber, and their fire-retardant properties due to chemical
coating were evaluated using cone calorimetry and a standard fire test. The woods used were Indonesian and Malaysian albizia
and gmelina plantation trees, with Japanese hinoki as a reference. The lumber was coated with 100 g/m2 of trimethylol melamine phosphoric acid in a 25% aqueous solution. The treated and untreated lumber was tested in a laboratory-scale
exposure furnace in accordance with JIS A 1304 and the cone calorimeter test with heat flux of 40 kW/m2 following the ISO 5660. Results showed that fire endurance of all lumber was enhanced by the treatment. The fire-retardant
properties were improved with increasing surface density. Though a similar trend was seen, the fire-retardant properties of
the lumber revealed by the cone calorimeter test were inferior to those seen with standard fire test. Addition of thermocouples
to the cone calorimeter allowed us to obtain information on the critical temperature (260°C) and charring temperature (300°C)
of the lumber.
Received: January 23, 2002 / Accepted: July 15, 2002
Acknowledgment The authors thank Dr. Shigehisa Ishihara, Professor Emeritus of the Wood Research Institute, Kyoto University for his suggestions
about this experiment. 相似文献
3.
Comparison of the decomposition behaviors of hardwood and softwood in supercritical methanol 总被引：2，自引：0，他引：2
The chemical conversion of Japanese beech (Fagus crenata Blume) and Japanese cedar (Cryptomeria japonica D. Don) woods in supercritical methanol was studied using the supercritical fluid biomass conversion system with a batch-type
reaction vessel. Under conditions of 270°C/27 MPa, beech wood was decomposed and liquefied to a greater extent than cedar
wood, and the difference observed was thought to originate mainly from differences in the intrinsic properties of the lignin
structures of hardwood and softwood. However, such a difference was not observed at 350°C/43 MPa, and more than 90% of both
beech and cedar woods were effectively decomposed and liquefied after 30 min of treatment. This result indicates that the
supercritical methanol treatment is expected to be an efficient tool for converting the woody biomass to lower-molecular-weight
products, such as liquid fuels and useful chemicals.
Received: December 19, 2001 / Accepted: March 15, 2002
Acknowledgments This research has been done under the research program for the development of technologies for establishing an eco-system
based on recycling in rural villages for the twenty-first century from the Ministry of Agriculture, Forestry and Fisheries,
Japan and by a Grant-in-Aid for Scientific Research (B)(2) (no.12460144, 2001.4–2003.3) from the Ministry of Education, Culture,
Sports, Science and Technology, Japan.
This study was presented in part at the 45th Lignin Symposium, Ehime, Japan, October 2000 and the 51st Annual Meeting of the
Japan Wood Research Society, Tokyo, Japan, April 2001.
Correspondence to:S. Saka 相似文献
4.
We investigated a method for measuring the refining degree of bamboo charcoal using an alternating current. The bamboo charcoal
was made under heating conditions of 400°–900°C (set temperature) and 0—3 h (holding time at each set temperature). The qualities
of the bamboo charcoal could not be estimated from the yield, and electric tests were required. The effect of the variation
in sample thickness on the impedance could be ignored. Attaching two plate electrodes to the same surface of a specimen enabled
high accuracy and practical use. The impedance was found to be a suitable index for estimating the refining degree of the
bamboo charcoal, such as the specific electric resistance. We believe that bamboo changes from an insulator to a conductor
suddenly when processed at 600°–750°C for 0–2 h. It is possible that the integral of temperature with time in a specimen during
heating is useful for approximately estimating impedance. 相似文献
5.
Raman spectra were measured for Japanese cedar wood and bark pyrolyzed in a nitrogen atmosphere at various temperatures (200°–1100°C).
Two characteristic bands, near 1340 and 1590 cm−1, denoted as the D-band and G-band due to graphitic carbon, respectively, appeared on all the spectra; and the spectral features
changed markedly with increasing heat-treatment temperature (HTT). The Raman parameters (band position, band width, D/G ratio)
of the bands were deconvolved using of a curve-fitting method. There was no significant difference in the values of the parameters
between the wood and bark. The D-band position and the G-band width showed a marked HTT dependence in the region of 400°–800°C.
We described the correlations of the Raman parameters with HTT and investigated the availability of Raman spectroscopy as
a means for evaluating HTT.
Received: January 28, 2002 / Accepted: June 14, 2002 相似文献
6.
Dynamic viscoelastic properties of wood acetylated with acetic anhydride solution of glucose pentaacetate 总被引：1，自引：0，他引：1
Spruce wood specimens were acetylated with acetic anhydride (AA) solutions of glucose pentaacetate (GPA), and their viscoelastic
properties along the radial direction were compared to those of the untreated and the normally acetylated specimens at various
relative humidities and temperatures. Higher concentrations of the GPA/AA solution resulted in more swelling of wood when
GPA was introducted into the wood cell wall. At room temperature the dynamic Young's modulus (E′) of the acetylated wood was enhanced by 10% with the introduction of GPA, whereas its mechanical loss tangent (tan δ) remained almost unchanged. These changes were interpreted to be an antiplasticizing effect of the bulky GPA molecules in
the wood cell wall. On heating in the absence of moisture, the GPA-acetylated wood exhibited a marked drop in E′ and a clear tan δ peak above 150°C, whereas the E′ and tan δ of the untreated wood were relatively stable up to 200°C. The tan δ peak of the GPA-acetylated wood shifted to lower temperatures with increasing GPA content, and there was no tan δ peak due to the melting of GPA itself. Thus the marked thermal softening of the GPA-acetylated wood was attributed to the
softening of wood components plasticized with GPA.
Received: March 29, 2002 / Accepted: May 21, 2002
Correspondence to:E. Obataya 相似文献
7.
Intercalation of wood charcoal with sulfuric acid (H2SO4) was investigated. Carbonized sugi (Japanese cedar) samples were prepared by heating at various temperatures in the range
1700°–2700°C. Electrochemical oxidization was carried out in H2SO4 and the feasibility of intercalation was determined. In potentiometric analysis, plateaus appeared for samples carbonized
at temperatures above 2300°C. In their X-ray diffraction profiles, the peak at around 26° was shifted to a smaller angle of
about 22.4°. These results can be considered as signs of intercalation with acid molecules. Fourier transform infrared analysis
of charcoal heated at 2700°C, following washing with water and drying of the sample, showed a band at 1220 cm−1 that was assigned to a sulfonate group. This band was not observed for samples heated at 1900°C. These observations suggest
the occurrence of intercalation in the former charcoal, but not in the latter. It is concluded that wood charcoal can undergo
intercalation when it has ordered stacking of hexagonal carbon layers.
Part of this article was presented at the 55th, 56th, and 57th Annual Meetings of the Japan Wood Research Society, Akita,
Hiroshima, and Tsukuba, August 2006, August 2007, and March 2008, respectively, and at the International Conference on Carbon
“CARBON 2008,” Nagano, July 2008 相似文献
8.
Relaxation mechanism of residual stress inside logs by heat treatment: choosing the heating time and temperature 总被引：1，自引：0，他引：1
Some methods to reduce residual stress inside logs have been reported, although the conditions for stress relaxation are
not yet clarified. Our study using precise experiments revealed that residual stress relaxation occurs only when both heat
and moisture exist inside the logs. We then determined the heating time and temperature required to relax the residual stress
inside the logs. Short air-drying treatments did not relax residual stress even though free water in the logs was greatly
reduced. The residual stress of the 33-h 80°C-heated bolts was relaxed, whereas that of the 48-h 70°C-heated bolts was not.
As for the influence of treatment time, bolts heated at 100°C were relaxed after 18 h of treatment. The 13-h heated bolts
did not show any relaxation. Therefore, residual stress relaxation occurred rapidly owing to the thermomechanical change of
the individual wood components comprising the cell wall. The moisture content inside all the bolts was much higher than the
fiber saturation point. This is because relaxation occurs only when the heating temperature is maintained above 80°C for a
particular duration of treatment.
Received: December 12, 2001 / Accepted: February 18, 2002
Present address: Institute for Structural and Engineering Materials, National Institute of Advanced Industrial Sciences and Technology, Independent
Administrative Institution, Nagoya 463-8560, Japan Tel. +81-52-736-7320; Fax +81-52-736-7419 e-mail: m.nogi@aist.go.jp
Part of this report was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000
Correspondence to:M. Nogi 相似文献
9.
To guide the development of thermal decomposition methods for disposal of CCA treated wood, reactions during the thermal
decomposition of CCA treated wood were modeled using thermogravimetric analysis (TGA), with special focus placed on arsenic
volatilization. Simple inorganic compounds, such as As2O5, CuO, and Cr2O3, were used to model the thermal behavior of the inorganics in CCA treated wood. In air and nitrogen, arsenic (V) oxide began
to volatilize at 600 °C during temperature ramps at 5 °C/min. During a 5 °C/min ramp in a hydrogen mix, arsenic (V) oxide
began decomposition at 425 °C. Arsenic volatile loss from CCA treated wood can depend strongly on the gases produced by wood
thermal decomposition. In the presence of As2O5, chromium (III) oxide and copper (II) oxide formed arsenates in air and nitrogen. Chromium arsenates began decomposition
as low as 790 °C. This suggested that chromium arsenates in CCA treated wood formed during original preservative fixation
may decompose as low as 790 °C. Copper arsenates were stable up to 900 °C in air, but showed only a limited range of stability
in nitrogen. Depending on process conditions, the formation of copper arsenates may limit arsenic loss during thermal decomposition
of CCA treated wood up to 900 °C. The thermal decomposition of inorganic oxides was influenced by interactions with wood and
wood decomposition products. In a dry YP sawdust/As2O5 mix, arsenic (V) oxide volatilized at 370 °C during inert pyrolysis at 5 °C/min and at 320 °C during smoldering combustion
at 5 °C/min. Thermal dwells of a dry YP/As2O5 mix showed no arsenic loss at 250 °C, but significant loss occurred during higher temperature dwells. During inert pyrolysis
at 5 °C/min, the formation of complexes and hydrates were shown to prevent arsenic loss up to 400 °C.
Received 14 July 1999 相似文献
10.
C and N stocks under three plantation forest ecosystems of Chinese fir, Michelia macclurei and their mixture 总被引：1，自引：0，他引：1
Chinese fir (Cunninghamia lanceolata), a type of subtropical fast-growing conifer tree, is widely distributed in South China. Its plantation area covers more
than 7 × 106 hm2, accounting for 24% of the total area of plantation forests in the country. In recent decades, the system of successive plantation
of Chinese fir has been widely used in southern China due to anticipated high economic return. However, recent studies have
documented that the practice of this system has led to dramatic decreases in soil fertility and forest environment as well
as in productivity.
Some forest ecologists and managers recognize the ecological role performed by broadleaf trees growing in mixtures with conifers,
and a great deal of studies on mixture effects have been conducted, particularly on mixture species of temperate and boreal
forests, but these research results were not completely consistent. Possibilities include dependence of the mixture effects
in large part to specific site conditions, the interactions among species in mixtures and biological characteristics of species.
Although some researchers also studied the effects of mixtures of Chinese fir and broadleaf tree species on soil fertility,
forest environment and tree growth status, little information is available about the effects of Chinese fir and its mixtures
with broadleaves on carbon and nitrogen stocks.
The experimental site is situated at the Huitong Experimental Station of Forest Ecology, Chinese Academy of Sciences, Hunan
Province (26°40′–27°09′ N, 109°26′–110°08′ E). It is located at the transition zone from the Yunnan-Guizhou Plateau to the
low mountains and hills of the southern bank of the Yangtze River at an altitude of 300–1,100 m above mean sea level. At the
same time, the site is also a member of the Chinese Ecosystem Research Network (CERN), sponsored by the Chinese Academy of
Sciences (CAS). This region has a humid mid-subtropical monsoon climate with a mean annual precipitation of 1,200–1,400 mm,
most of the rain falling between April and August, and a mean temperature of 16.5°C with a mean minimum of 4.9°C in January
and a mean maximum of 26.6°C in July. The experimental field has red-yellow soil.
After a clear-cutting of the first generation Chinese fir (Cunninghamia lanceolata) plantation forest in 1982, three different plantation forest ecosystems, viz. mixture of Michelia macclurei and Chinese fir (MCM), pure Michelia macclurei stand (PMS) and pure Chinese fir stand (PCS), were established in the spring of 1983. A comparative study on C and N stocks
under these three plantation forest ecosystems was conducted in 2004. Results showed that carbon stocks were greater under
the mixtures than under the pure Chinese fir forest and the pure broad-leaved forest, and the broadleaves and the mixtures
showed higher values in nitrogen stocks compared with the pure Chinese fir forest. The spatial distribution of carbon and
nitrogen stocks was basically consistent, the value being greater in soil layer, followed by tree layer, roots, understory
and litter layer. The carbon and nitrogen stocks in soil layer were both highly correlated with the biomass in understory
and litter layer, indicating that understory and forest litterfall exerted a profound effect on soil carbon and nitrogen stocks
under plantation ecosystems. However, correlations among soil carbon, nitrogen stocks and below ground biomass of stand have
not been observed in this study.
Translated from Acta Ecologica Sinica, 2005, 25(12): 3,146–3,154 [译自: 生态学报] 相似文献
11.
The effects of pasture fertilization frequency and two vertical positions in the stem on elasticity and strength parameters
during static bending (modulus of elasticity, stress at proportional limit, modulus of rupture) of Pinus radiata wood growing in a silvopastoral system were evaluated. Twenty-seven trees were selected randomly from three silvopastoral
trials established at Tanumé Experimental Center (34°9′–34°15′ S; 72°53′–72°59′ W). The results indicated that pasture fertilization
frequency had no significant effect on the physical and mechanical parameters evaluated. However, the vertical position in
the stem did have a significant effect on stress at the proportional limit and on the modulus of rupture due to different
average values for the annual ring width and nominal density found in the specimens obtained from logs at two different heights
of the stem.
Received: February 20, 2002 / Accepted: June 5, 2002
Acknowledgments The authors thank the following institutions and people for their support: CONAF, VI Region; Dr. Rolando Rodríguez, CONAF
VIII Region; Cesar Cabrera, Forestry Engineer, CONAF VI Region; Osvaldo Herrera, Director of Experimental Center “Tanumé”;
Dr. Manuel Sánchez, Faculty of Forestry Sciences, University of Concepción; Dr. Glenn Hofmann, Faculty of Physics and Mathematics,
University of Concepción; Alex Opazo, M.Sc.(C), Faculty of Forestry Sciences, University of Concepción; Staff of Experimental
Center “Tanumé”.
Correspondence to:M.H.R. Vidal 相似文献
12.
Thermal conductivity and diffusivity of wood 总被引：5，自引：0，他引：5
Summary Transient simultaneous measurements of thermal conductivity and diffusivity of Swedish wood have been performed with the
plane source technique on oven-dry hardwood (birch) samples at room temperature and at 100 °C. The influences of temperature,
density, porosity and anisotropy on thermal conduction were investigated. The measurements were done in longitudinal (parallel
to the grain) and transverse (intermediate between radial and tangential) directions. As the temperature increased from 20
to 100 °C, the thermal conductivity of each sample increased slightly for both longitudinal and transverse directions. The
effect of density and porosity on the thermal conductivity may be related to the presence of other scattering mechanisms such
as voids and cell boundaries. It seems that the dominant mechanism of heat transfer across the cell lumina in these types
of wood is the heat conduction through the voids. An attempt was made to explain the behaviour of the effective thermal conductivity
by adopting a model based on the ratio between heat conduction in parallel and serial layers of gas, liquid, and solid phases.
Received 7 May 1997 相似文献
13.
Delignified hinoki wood and cellulose as well as hinoki and lauan woods were carbonized at 590°C for 1 h. The dielectric properties
of these specimens were measured at 20°C in a frequency range of 20 Hz to 1 MHz. Inflection points in the dielectric constant
(ε′) versus the logarithm of frequency (log f) curves as well as in the logarithm of the electric conductivity (log σ) versus log f curves for all specimens prepared were recognized. Peaks in the dielectric loss and the imaginary part of the complex conductivity
versus the log f curves were detected in the frequency location corresponding to the inflection point in the ε′ and log σ versus log f curves. It was considered that this relaxation was responsible for the interfacial polarization observed in heterogeneous
materials because no permanent dipoles existed in the specimens carbonized above 500°C. The Cole–Cole circular arc law was
applied to account for this relaxation. Similar average relaxation times were obtained for all specimens. These results suggested
that the observed relaxation was ascribed to interfacial polarization at microscopic levels in the cell walls. 相似文献
14.
Somatic embryogenesis in Chamaecyparis pisifera Sieb. et Zucc. was initiated from immature seeds collected from the end of June to early July. Mass propagation through adventitious
shoot bud production from somatic embryo culture on Woody Plant (WP) medium and artificial seed production using sodium alginate
was achieved. A high bud forming index value (25.8) was obtained on medium supplemented with 1 μM 6-benzylaminopurine. The conversion rates from artificial seeds under aseptic and nonaseptic conditions were 60%–100% and
10%–12%, respectively. For germplasm conservation, somatic embryos and embryogenic cells were successfully stored at 4°C (medium-term
storage) and in liquid nitrogen for long-term storage.
Received: December 21, 2001 / Accepted: August 1, 2002
Acknowledgments This work was supported in part by the Japan Science and Technology Corporation and in part by a Grant for Research for the
Future Program from the Japan Society for the Promotion of Science.
Correspondence to:E. Maruyama 相似文献
15.
Guangjie Zhao Wensheng Luo T. Furuno Qiang Ren Erni Ma 《Frontiers of Forestry in China》2007,2(2):231-236
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] 相似文献
16.
A. Venkateswaran 《Wood Science and Technology》1974,8(1):50-55
Summary Wood thermal conductivities (from the literature) are directly related to the electrical properties of the same species (measured by the author) in the density range occurring in nature.The correlation coefficient between permittivity and conductivity was found to be higher than that between conductivity and density for various species of wood. Variation in the chemical components of woods results in variation in the thermal conductivities of woods.The author wishes to thank Dr. M. N. Carroll and Mr. D. G. Miller of this Laboratory for profitable discussions. 相似文献
17.
On the loss factor of wood during radio frequency heating 总被引：2，自引：0，他引：2
The radial direction loss factor of full-size western hemlock sapwood and heartwood, as well as western red cedar heartwood
timbers was measured using the direct calorimetric method with a laboratory-scale radio frequency/vacuum dryer at the frequency
of 13.56 MHz, moisture content range between 10 and 80%, temperature range between 25 and 55 °C, and root mean square (rms)
electrode voltages of 0.8 and 1.1 kV, respectively.
The results indicated that the moisture content, temperature, electric field strength and wood type significantly affected
the loss factor. Empirical regression equations were derived based on the experimental data that made possible the calculation
of the loss factor and power density within wood during RF heating.
Received 18 January 1997 相似文献
18.
The relations among internal temperature, internal pressure, and moisture content distribution in sugi square lumber during
high-frequency (HF) heating were determined to clarify the mechanism of water movement during the combination of HF heating
and hot air exposure. Green sugi square lumbers were subjected to HF heating under atmospheric pressure. The water movement
and pathways in the lumber during HF heating were also investigated. Results showed that internal pressure is the driving
force of water movement. HF heating causes a rise in the internal temperature and internal pressure in sugi square lumber.
Ordinarily, water in lumber evaporates from the surfaces of lumber during hot air drying. However, with HF heating the internal
pressure is generated by the increased temperature, and liquid water is driven not only parallel to the grain but also perpendicular
to the grain of the lumber. The ratio of the amount of liquid flow in the parallel and perpendicular directions ranged from
2 : 3 to 1 : 3. When the movement of water in the lumber was traced with a 0.5% aqueous solution of acid fuchsin, water was
found to move through the lumber in the longitudinal direction and then flow in a direction perpendicular to the grain or
in the radial and tangential directions.
Received: June 15, 2001 / Accepted: February 8, 2002
Acknowledgment The authors thank Dr. O.R. Pulido, Institute of Wood Technology, Akita Prefectural University, for discussions and for proofreading
this paper.
Part of this research was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001
Correspondence to:Y. Kawai 相似文献
19.
Feasibility of supercritical carbon dioxide as a carrier solvent for preservative treatment of wood-based composites 总被引：4，自引：0，他引：4
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 相似文献