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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Wood Science and Technology
Journal Basic Information
Journal DOI :
The Korean Society of Wood Science Technology
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Volume & Issues
Volume 25, Issue 4 - Dec 1997
Volume 25, Issue 3 - Sep 1997
Volume 25, Issue 2 - Jun 1997
Volume 25, Issue 1 - Mar 1997
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Synthesis of Aromatic and Aliphatic Compound from Kraft Oak Lignin and Acetosolve Straw Lignin by Thermochemical Liquefaction
Lee, Byung-G. ;
Journal of the Korean Wood Science and Technology, volume 25, issue 1, 1997, Pages 1~7
Kraft oak lignin and ricestraw lignin from acetosolve pulping were dissolved in 50/50 mixture of tetralin/m-cresol solvent. The dissolved lignin was reacted in the pressurized autoclave which was operating at
of reaction temperature and 10~20 atms of reaction pressure respectively_Hydrogen pressure of 60~80kg/
was exercising into the pressurized autoclave reactor to create thermochemical hydrogenolysis reaction. It was identified by GLC, GC-MS and HPLC that the alkyl-aryl-
-O-4 ether bond of lignin was cleaved and degraded into various smaller molecules of aromatic compound such as phenols and cresols under the reaction conditions around
and 10 atms of reaction temoerature and pressure. Hydrogenolysis reaction of lignin compound which was done above
of reaction temperature and 20 atms of reaction pressure showed that the amount of aromatic compound such as phenols and cresols degraded from reactant lignin was decreasing with newly present and increasing water out of product mixtures. It was supposed that new aliphatic compound of high molecular weight hydrocarbon is composed due to higher reaction temperature and pressure of hydrogenolysis reaction such as
and 20 atms, even though it was almost impossible, to identify what kind of degraded products it was by HPLC.
Evaluation of Static Bending Properties for Some Domestic Softwoods and Tropical Hardwoods Using Sonic Stress Wave Measurements
Lee, Do-Sik ; Jo, Jae-Sung ; Kim, Gyu-Hyeok ;
Journal of the Korean Wood Science and Technology, volume 25, issue 1, 1997, Pages 8~14
Stress wave velocity, wave impedance, and stress wave elasticity of small, clear bending specimens of five domestic softwoods (Pinus densiflora, Pinus koraiensis, Chamaecyparis obtusa, Cryptomeria japonica, and Larix leptolepis) and four tropical hardwoods(Kempas, Malas, Taun, and Terminalia) were correlated with static bending modulus of elasticity(MOE) and modulus of rupture(MOR). The degree of correlation between stress wave parameters and static bending properties was dependent on wood species tested. Stress wave elasticity and wave impedance were better predictors for static bending properties than stress wave velocity for each species individually and for softwood or hardwood species taken as a group, even though elasticity and impedance were nearly equally correlated with static bending properties apparently. Based upon the correlation coefficient between stress wave parameters and static properties, stress wave elasticity and wave impedance were found as stress wave parameters which can be used for the purpose of the reliable and successful prediction of bending properties. The degree of correlation between static MOE and MOR was also different according to wood species tested. Static MOE was nearly as well correlated with MOR as was stress wave elasticity. The results of this research are encouraging and can be considered as a basis for further work using full-size lumber. From the results of this study, it was concluded that stress wave measurements could provide useful predictions of static bending properties and was a feasible method for machine stress grading of domestic softwoods and tropical hardwoods tested in this study.
Studies on Improving Preservative Treatability of Japanese Larch Heartwood by Presteaming
Kang, Sung-Mo ; Paik, Ki-Hyon ; Kim, Gyu-Hyeok ;
Journal of the Korean Wood Science and Technology, volume 25, issue 1, 1997, Pages 15~22
The effectiveness of presteaming for improving CCA treatability on refractory Japanese larch heartwood was investigated in this study. Presteaming was effective on improving treatability, and the extent of improvement was dependent on moisture contents of wood specimen and steaming conditions. Green wood showed higher average value in both preservative retention and penetration than dry wood, and steaming under pressure conditions also had higher treatability than steaming at atmospheric conditions. The degree of improvement for treatability was increased with the extension of steaming period. Treatability of dry wood pres teamed under pressure conditions more than 6 hours and green wood for 3 hours was similar to that enhanced by conventional incising. Presteaming green wood under pressure conditions more than 6 hours was more effective than conventional incising in improvement of CCA treatability, and resultant treatability satisfied a minimum value required for CCA-treated wood for being used at the regions of hazard class H3 and H4. In addition, an improvement of treatability by presteaming was due to an increase in permeability resulted from the degradation of hemicelluloses within aspirated pit membrane and cell wall, not the removal of extractives from pit membrane. The reduction in strength, measured as longitudinal compressive strength, due to pres teaming was related with the degradation of hemicelluloses, and was increased as steaming conditions were severe. The degree of strength reduction associated with presteaming treatment to obtain required treatability could be quantified from the relatively good relation between the increase in treatability and the decrease in strength.
Quantitative Variation of Alkali-soluble Extracts from Coniferous Barks for Tannin-based Adhesives
Cho, Nam-Seok ; Kim, Young-Sin ; Han, Gyu-Seong ;
Journal of the Korean Wood Science and Technology, volume 25, issue 1, 1997, Pages 23~27
Alkali-soluble extracts were prepared from barks of Japanese larch(Larix leptolepis). Siberian larch(Larix gmelineii) and Radiata pine(Pinus radiata) The effect of various factors, such as particle size, liquor ratio, extraction temperature, and reaction time, on the extracts yield was investigated. Particle sizes affected the alkali-soluble extracts; the finer the particle size, the higher extracts and extract efficiency. High temperature and high liquor ratio were more effective. In the range of 0.25% to 1% NaOH concentration, alkali extracts were increased with the increasing alkali concentration. However, extract yields were leveled off above 0.5% alkali concentration. Extractions with NaHCO3 were almost equivalent to those of NaOH extraction. 1% NaOH and 1% NaHCO3 resulted in the highest yields of alkaline extracts. Extracts from Japanese larch were lower than those from Siberian larch and Radiata pine barks. Siberian larch bark was the best raw material for tannin adhesives, because its extractive yield was higher than those of the other barks. Concerning pH of alkaline media during extraction, small increases of the extract yields were resulted at range of pH 7 to pH 9, while a large increases from pH 9.0 to pH 12. This phenomenon is attributed to higher alkalinity.
Comparison of Air-Drying Process in Four Seasons for Some Softwood Lumbers
Jung, Hee-Suk ; Lee, Nam-Ho ; Lee, June-Ho ; Kwon, Ju-Yong ;
Journal of the Korean Wood Science and Technology, volume 25, issue 1, 1997, Pages 28~36
Several thick board and dimension lumbers of Japanese larch(Larix leptolepis), Dahurian larch(Larix gmelini) and radiata pine(Pinus radiata) air-dried in four different seasons to compare air-drying process. Patterns of air-drying curves were influenced by climatological conditions and limber thickness. The initial drying rates of summer were the highest, followed those of fall, spring and winter. The drying times to equilibrium moisture contents for four seasons were nearly the same except for winter. However, the drying time for winter required twice more time than the other seasons. The drying time of dimension lumbers required 1.3 times more than boards. The final moisture contents were lowest during spring, highest during winter and similar between summer and fall.
Ultrafiltration Characteristics of Hot-Water Extracts from Siberian Larch Barks for Tannin-based Adhesives
Cho, Nam-Seok ;
Journal of the Korean Wood Science and Technology, volume 25, issue 1, 1997, Pages 37~41
Hot-water soluble extracts were prepared from medium-sized barks of Siberian larch (Larix gmelineii). The extracts were fractionated by ultrafiltration method for producing uniform quality of adhesives. Molecular weight distribution of the extracts was ranged of 100 to 300.000. pH of the extracts affected amounts of flux, and the range of pH 6~pH 8 was proper for wood adhesives, because of easy concentration and fast gelation time. Removal of particles greater than
from the extracts increased both filtration speed (flux) and yields of solids in the filtrates. In ultrafiltration process. operating pressure, filtrate temperature, and flow rate significantly increased with the increase of individual condition. Ultrafiltration using PM10 membrane was very effective to fractionate and concentrate the extracts. Removal of large particles greater than 0.45 m from the extracts increased filtration speed(flux) and yields of solids in the filtrates. A gelation time was accelerated with the increasing pH of the extracts and its concentration. The Stiasny precipitate(26%) from the filtrate obtained by PM 10 membrane was very lower than that(78%) of the retentates. This ultrafiltration method was efficient for obtaining high yield purified phenolic compounds.
Estimation of the Dynamic MOE in Woods with Resonance Frequency
Lee, Weon-Hee ; Hwang, Kweon-Hwan ;
Journal of the Korean Wood Science and Technology, volume 25, issue 1, 1997, Pages 42~49
The purpose of this study was to investigate the relationships among density, moisture content, and modulus of elasticity in which are important characteristics in physical and mechanical properties of woods. In this study, the dynamic MOE was calculated through the combination with resonance frequency of transverse vibration method and density, and the estimated moisture contents were calculated with two different equations (1, 2) in order to compare with experimental moisture contents. The following results from this study were obtained: 1. According to the regression analysis with two different parameters (E and density), the two regression lines appeared to be straight intersecting at 0.6 density. As another factor, moisture contents in wood also influenced on the analysing regression at the below F.S.P. 2. When considering the relationship between moisture contents and E, the tendency of each moisture content and E showed very similar pattern suggesting that moisture contents in addition to density are very important parameter. 3. When together with moisture contents and density as parameters for multiple regression analysis, coefficiences of determinations are dramatically improved. Interestingly, the coefficiences of determinations are further increased when analysing at the below point of F.S.P. and when analysing higher and lower density separately. In summary, more correct estimation of the dynamic MOE of woods can be possible with only transverse vibration and density in wood. Therefore, with this indirect method, the calculation of MOE in all kinds of woods including timber, live tree and wood products can be feasible resulting in accelerating the efficiency of time and labor.
Manufacture and Its Properties of MDF Using Paper Sludge and ONP
Kim, Bong-Yong ;
Journal of the Korean Wood Science and Technology, volume 25, issue 1, 1997, Pages 50~55
This study was carried out to utilize old newspaper(ONP) and paper sludge more effectively, and also to elucidate the influences of pressing conditions on the medium density fiberboard(MDF) properties. MDFs were made from ONP and low grade of paper sludge by wet process with change of pressing time, temperature and pressure. MDFs of ONP were more affected by pressing conditions, especially pressing pressure, but temperature and pressing time were also important. According to mixing paper sludge to ONP tensile and bending strength of MDF were decreased, but density and dimensional stability were improved. These results indicated that some physical properties of MDF can be improved by paper sludge and it is possible to use it in MDF.
A Study on Chemical Modification Effect of Papermaking Fiber by Cyanoethylation
Yoon, Se-Young ; Jo, Byoung-Muk ; Oh, Jung-Soo ;
Journal of the Korean Wood Science and Technology, volume 25, issue 1, 1997, Pages 56~64
Since there are three hydroxyl groups on each anhydroglucose ring of the cellulose, the renewable resources, we can get various functional papers by the chemical modification of cellulose. The reaction involving the introduction of the
-CN) group into organic substances containing reactive hydrogen atoms is known as cyanoethylation. Cellulose reacts with acrylonitrile in the presence of strong alkalis in a typical manner of primary and secondary alcohols to form cyanoethyl ethers. In cyanoethylation, important factors of reaction are temperature, concentration of the NaOH, and addition rate of acrylronitrile. FT-IR spectra of cyanoethyl group was confirmed at
, which corresponds the introduction of aliphatic nitrile group. Effect of cyanoethyl DS(degree of substitution) on strength properties was resulted that cyanoethylated BKP of DS 0.04 appeared to be the best choice for overall strength properties. Also, excellent thermal stability in aging characteristics was obtained.
The Production of Alcohol from Municipal Waste(II) - The Effects of Physical or Chemical Treatment on the Enzymatic Hydrolysis of Waste Paper -
Lim, Bu-Kug ; Yang, Jae-Kyung ; Lee, Jong-Yoon ;
Journal of the Korean Wood Science and Technology, volume 25, issue 1, 1997, Pages 65~70
The effects on the enzymatic hydrolysis of waste paper treated with physical or chemical treatment were investigated. To gain the higher saccharification rate, physical or chemical treatment are necessary in enzymatic conversion process of waste paper. The major deterrents to the effective utilization of waste paper for enzymatic conversion process are phenolic compounds, cellulose crystallinity and coating materials. In the enzymatic hydrolysis of waste paper, the deterrents through enzymatic conversion process can be eliminated by the physical or chemical treatment. This study was performed to obtain the optimal condition for enzymatic conversion process of non-treated waste paper and to review effects on enzymatic conversion process of waste paper treated with physical or chemical methods. In the aspect of saccharification rate, waste paper treated with 1.5% sodium hypochlorite was the most effective and in physical treatment methods, multi-stage treatment(autohydrolysis+refining treatment) was more effective than the other physical treatment.