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211.
Jianying Xu Ragil Widyorini Hidefumi Yamauchi Shuichi Kawai 《Journal of Wood Science》2006,52(3):236-243
Binderless fiberboards with densities of 0.3 and 0.5 g/cm3 were developed from kenaf core material using the conventional dry-manufacturing process. The effects of steam pressure (0.4–0.8
MPa) and cooking time (10–30 min) in the refining process, fiber moisture content (MC) (10%, 30%), and hot-pressing time (3–10
min) on the board properties were investigated. The results showed that kenaf core binderless fiberboards manufactured with
high steam pressure and long cooking time during the refining process had high internal bond (IB) strength, low thickness
swelling (TS), but low bending strength values. The binderless fiberboards made from 30% MC fibers showed better mechanical
and dimensional properties than those from air-dried fibers. Hot-pressing time was found to have little effect on the IB value
of the binderless board at the refining conditions of 0.8 MPa/20 min, but longer pressing time resulted in lower TS. At a
density of 0.5 g/cm3, binderless fiberboard with the refining conditions of 0.8 MPa/20 min recorded a modulus of rupture (MOR) of 12 MPa, modulus
of elasticity (MOE) of 1.7 GPa, IB of 0.43 MPa, and 12% TS under the optimum board manufacturing conditions.
Part of this article was presented at the 54th Annual Meeting of the Japan Wood Research Society, Hokkaido, August 3–5, 2004 相似文献
212.
Elastic moduli and stiffness optimization in four-point bending of wood-based sandwich panel for use as structural insulated walls and floors 总被引:1,自引:0,他引:1
Tamami Kawasaki Min Zhang Qian Wang Kohei Komatsu Shuichi Kawai 《Journal of Wood Science》2006,52(4):302-310
Several wood-based sandwich panels with low-density fiberboard core were developed for structural insulated walls and floors,
with different face material, panel thickness, and core density. The elastic moduli with and without shear effect (E
L, E
0) and shear modulus (Gb) were evaluated in four-point bending. Generally, the stiffer face, thicker panel, and higher core density were advantageous
in flexural and shear rigidity for structural use, but the weight control was critical for insulation. Therefore, optimum
designs of some virtual sandwich structures were analyzed for bending stiffness in relation to weight for fixed core densities,
considering the manufactured-panel designs. As a result, the plywood-faced sandwich panel with a panel thickness of 95 mm
(PSW-T100), with insulation performance that had been previously confirmed, was most advantageous at a panel density of 430
kg/m3, showing the highest flexural rigidity (E
L
I = 13 × 10−6 GNm2) among these panels, where E
L, E
0, and G
b were 3.5, 5.5, and 0.038 GN/m2, respectively. The panel was found to be closest to the optimum design, which meant that its core and face thickness were
optimum for stiffness with minimum density. The panel also provided enough internal bond strength and an excellent dimensional
stability. The panel was the most feasible for structural insulation use with the weight-saving structure. 相似文献
213.
KAWAI Shuichi 《中国林业科技(英文版)》2007,6(2):7-13
Light-weight composite panels were manufactured using kenaf core particles as core material and kenaf bast fiber-woven sheets as top and bottom surfaces. Methylene diphenyldiisocyanate (MDI) resin was used as the adhesive with the resin content of 4% for core particles and 50 g/m^2 for bast fiberwoven sheets. The target board densities were set at 0.35.0.45 and 0.55 g/cm^3. The composite panels were evaluated With Japanese Industrial Standard for Particleboards (JIS A 5908- 2003).The results show that the composite panel has high modulus of rupture and internal bonding strength. The properties of 0.45 g/cm^3 density composite panel are: MOR 20.4 MPa. MOE 1.94 MPa, IB 0.36 MPa, WA142%, TS 21%. Kenaf is a good raw material for making light-weight composite panels. 相似文献
214.
The thermo-oxidative degradation of various polyol-added isocyanate resins for wood adhesives was studied using differential scanning calorimetry and thermogravimetry. The degradation of the resin cured with water began at 150°C. When a certain polyol was added to the resin at an NCO/OH ratio of 25 in addition to water, the cured resin began to degrade at 200°C. To clarify the cause of the good thermal stability in polyol-added resins, the effect of various polyols on the reactivity of isocyanate was investigated. It was found that the reactivity of isocyanate was enhanced by the addition of a dipropylene glycol and glycerin-type polyols. In addition, the effect of the NCO/ polyol-OH ratio was investigated using dipropylene glycoltype polyol. The reactivity of isocyanate increased with increasing polyol content. The thermal stability of the resin was improved to a certain degree by addition of a small amount of the polyol but deteriorated when a large amount of the polyol was added.Part of this paper was presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 1998 相似文献
215.
Development of binderless particleboard from kenaf core using steam-injection pressing 总被引:3,自引:4,他引:3
Binderless particleboards were successfully developed from kenaf core using the steam-injection press. The effects of board density, steam pressure, and treatment time on the properties of the board were evaluated. The target board densities were relatively low, ranging from 0.40 to 0.70g/cm3. The properties [i.e., moduli of rupture (MOR) and elasticity (MOE) in both dry and wet conditions, internal bonding strength (IB), and water absorption (WA)] of the boards increased linearly with increasing board density. Steam pressure and treatment time also affected the board properties. The bending strength and IB were improved with increased steam pressure. A long steam treatment time contributed to low thickness swelling (TS) values and thus better dimensional stability. The appropriate steam pressure was 1.0MPa, and the treatment time was 10–15min. The properties for 0.55g/cm3 density boards under optimum conditions were MOR 12.6MPa, MOE 2.5GPa, IB 0.49MPa, TS 7.5%, and wet MOR 2.4MPa. Compared with the requirement of JIS 5908, 1994 for particleboard, kenaf binderless boards showed excellent IB strength but relatively poor durability.Part of this report was presented at the 19th Annual Meeting of the Japan Wood Technological Association, Tokyo, October 2001 相似文献
216.
Ragil Widyorini Takashi Higashihara Jianying Xu Takashi Watanabe Shuichi Kawai 《Wood Science and Technology》2005,39(8):651-662
We investigated optimum self-bonding conditions of kenaf core composites manufactured by steam treatment, and discussed on
the roles of cinnamic acids in the self-bonding mechanism. The presence of cinnamic acids in the kenaf core and its composites
were analyzed by pyrolysis gas chromatography-mass spectrophotometry in the presence of tetramethyl ammonium hydroxide (TMAH/Py-GC-MS).
The results showed that the optimum bonding properties of kenaf core composites were achieved under these conditions: steam
pressure of 0.8–1.0 MPa and pressing time of 10–15 min were able to provide shear strength of 0.40–0.42 MPa while having 2–5%
of weight loss. Lignin analysis showed that steam-treated kenaf core composites had a lower proportion of syringyl- to guaiacyl-derived
moieties and also cinnamic acids to guaiacyl-derived moieties than its native counterpart. The results indicated that some
parts of the ester-linked cinnamic acids were also cleaved due to the degradation of hemicelluloses and lignin during steam
treatment. Based on these results, it was concluded that in addition to three main components, the cinnamic acid was also
suggested to participate in the self-bonding mechanism of non-wood lignocellulosic binderless boards. 相似文献
217.
Thomas Walther S. Nami Kartal Won Joung Hwang Kenji Umemura Shuichi Kawai 《Journal of Wood Science》2007,53(6):481-486
The development of oriented fiberboards made from kenaf (Hibiscus cannabinus L.) and their suitability as a construction material has been investigated. Three different types of boards consisting of
five layers with individual orientations were prepared using a combination of low molecular weight and high molecular weight
phenol-formaldehyde (PF) resin for impregnation and adhesion purposes. Additional boards with the same structure were prepared
using high molecular weight PF resin only. The mechanical properties of the boards have been examined as well as their resistance
against fungal decay and termite attack. All kenaf fiberboards showed elevated mechanical properties compared with medium-density
fiberboard made from wood fibers, and showed increased decay and termite resistance. Differences in the decay and termite
resistance between the board types were caused by the presence of the low molecular weight PF resin for the impregnation of
the fibers. No significant difference was found for the mechanical properties. The effect of the PF resin for impregnation
was much clearer in fungal decay resistance than for termite resistance; however, fiber orientation had no effect on both
decay and termite resistance of the specimens. 相似文献
218.
Water removal of wet veneer by roller pressing 总被引:2,自引:0,他引:2
Koji?AdachiEmail author Masafumi?Inoue Kozo?Kanayama Roger M.?Rowell Shuichi?Kawai 《Journal of Wood Science》2004,50(6):479-483
High moisture content, flat sawn Japanese cedar (Cryptomeria japonica D. Don) veneer was compressed using a roller press to mechanically remove water. The amount of water removed depended on the amount of compression applied. At 60% compression, 400kg/m3 of water was removed. The process was not dependent on the size of the wood, the degree of compression, or the feed speed of the specimen. After compression, the remaining water contents were evenly distributed throughout the veneer regardless of the length of the specimen. The specimens did not completely recover to original thickness. High compression ratio and low temperature intensified the reduction of thickness. The bending strength after compression decreased in an inversely proportional manner with the thickness of the specimen and the compression degree.Part of this study was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000 相似文献
219.
Sakae Horisawa Yoh Sakuma Yutaka Tamai Shuichi Doi Minoru Terazawa 《Journal of Wood Science》2001,47(2):154-158
The optimum environmental temperature for a biodegrading machine using wood particles as a matrix was investigated using a small-scale degradation reactor and model waste. The biodegradation rate was evaluated by weight loss of waste and CO2 evolution. The degradation reaction was restricted only by adjusting the environmental temperature while sufficient oxygen and substrates were supplied. Results suggested that the optimum temperature for degradation was 30°–40°C for exploiting biological activity effectively with the lowest use of energy. Bacteria from the environment propagated in the reactor with no inoculum added. The microbial flora changed during the operation time but had no effect on the biodegradation rate.Part of this report was presented at the 48th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1998 相似文献
220.
Kazufumi Nagata Tsuyu Ando Yasunori Nonoue Tatsumi Mizubayashi Noriyuki Kitazawa Ayahiko Shomura Kazuki Matsubara Nozomi Ono Ritsuko Mizobuchi Taeko Shibaya Eri Ogiso-Tanaka Kiyosumi Hori Masahiro Yano Shuichi Fukuoka 《Breeding Science》2015,65(4):308-318
Grain shape is an important trait for improving rice yield. A number of quantitative trait loci (QTLs) for this trait have been identified by using primary F2 mapping populations and recombinant inbred lines, in which QTLs with a small effect are harder to detect than they would be in advanced generations. In this study, we developed two advanced mapping populations (chromosome segment substitution lines [CSSLs] and BC4F2 lines consisting of more than 2000 individuals) in the genetic backgrounds of two improved cultivars: a japonica cultivar (Koshihikari) with short, round grains, and an indica cultivar (IR64) with long, slender grains. We compared the ability of these materials to reveal QTLs for grain shape with that of an F2 population. Only 8 QTLs for grain length or grain width were detected in the F2 population, versus 47 in the CSSL population and 65 in the BC4F2 population. These results strongly suggest that advanced mapping populations can reveal QTLs for agronomic traits under complicated genetic control, and that DNA markers linked with the QTLs are useful for choosing superior allelic combinations to enhance grain shape in the Koshihikari and IR64 genetic backgrounds. 相似文献