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Creep of Chinese Fir Wood Treated by Different Reagents

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Forestry Studies in China 2005年第1期7卷 40-45页

作者： XueFeng-lian ZhaoGuang-jie LuWen-hua collegeofmaterialsciencesandtechnology BeijingForestryUniversityBeijing100083ER.China

In order to investigate the effect of different reagents on changes of the crystalline region and amorphous region (Matrix) in wood cell walls, the creep behavior of Chinese fir (Cunninghamia lanceolata) wood treated with dimethyl sulfoxide (DMSO) and diethyl amine, sulfur dioxide and dimethyl sulfoxide mixture (DEA-SO2-DMSO), and the untreated wood at oven-dried, air-dry and water-saturated states during adsorption and desorption processes were all examined in air or in water. The measurements were carried out at ambient temperature and atmospheric pressure. The load is constant with 62 g or 0.607 6 N. The results obtained were as follows: 1) The instantaneous compliance J0 and the creep compliance J of specimens decrystallized with DEA-SO2-DMSO solution were bigger than those of DMSO swollen wood, and the latter was still much bigger than those of untreated wood. 2) For untreated wood, J0 and J increased with equilibrium moisture content (EMC) of wood, but there was not apparent correlation between wood EMC and the relative compliance. 3) Specimens treated with DMSO and DEA-SO2-DMSO mixture were recrystallized after immersion in water, and the degree of recrystallization of the former was larger. 4) For oven-dried specimens, the creep compliances in water were bigger than those in air. But for fiber-saturated and water-saturated specimens they were nearly equivalent to each other.

关键词： Chinese fir creep DMSO DEA-SO2-DMSO

Induced Discoloration of Buerger Maple during Drying Process

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Forestry Studies in China 2004年第2期6卷 50-55页

作者： GaoJianmin ZhangBiguang ChangJianmin collegeofmaterialsciencesandtechnology BeijingForestryUniversityBeijing100083P.R.China

Buerger maple (Liquidambar formosana Hance) is a kind of wood that is easily discolored. This paper tries to obtain satisfactory color and a broad prospect in the utilization of buerger maple by induced discoloration. The authors analyze the mechanism of induced discoloration of buerger maple based on the analysis of visual physical parameter, the infrared spectrum (IRS) and the scanning electron microscope (SEM) under different drying conditions. The result shows that it is feasible to induce discoloration during the drying process. The wood color tends to be red and fuscous during inducing discoloration of buerger maple. The induced discoloration mechanism is: 1) the high temperature and humidity accelerates the oxidation reaction of polyphenol, leuco-fancy pigment and tannin, which changes the wood color to red; 2) the hydroxy ( OH) is oxidized and the carbonyl ( C O), carboxyl ( COOH), ester and ketone groups form during the high temperature steaming, which results in wood piece discoloration.

关键词： buerger maple drying process induced discoloration

Drying Characteristics of Wood under Vacuum-superheated Steam

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Forestry Studies in China 2004年第2期6卷 41-45页

作者： YiSonglin ZhangBiguang ChangJianmin DuChaogang collegeofmaterialsciencesandtechnology BeijingForestryUniversityBeijing100083P.R.China

This paper presents comparison and analysis of thermal-dynamic characteristics of air-drying and superheated steam drying under vacuum. The result reveals that for both convective heat transfer coefficient and resistance of mass transfer on the surface, superheated steam drying under vacuum is superior to air-drying under the same condition. With Masson pine as specimen, we found that the inversion temperature really exists through comparable experiments of air-drying and superheated steam drying under vacuum. When temperature is above inversion point of temperature, drying speed is faster than that of air-drying; however, if temperature is below the point, the result is opposite. The inversion temperature of experiment ranges from 80 to 85 ℃.

关键词： wood drying vacuum superheated steam inversion temperature

Effects of Phosphoric Acid on Liquefaction of Wood in Phenol and Optimum Liquefaction Processing Parameters

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Forestry Studies in China 2004年第3期6卷 50-54页

作者： ZhangQiuhui ZhaoGuangjie JieShujun collegeofmaterialsciencesandtechnology BeijingForestryUniversityBeijing100083P.R.China

To clarify the influencing factors of liquefaction of wood in phenol using phosphoric acid as a catalyst and get its liquefaction technology, a study on the liquefaction technology of Chinese fir (Cunninghamia lanceolata) and poplar (triploid Populus tomentosa Carr) under different conditions was conducted. The results indicate that the residue rate decreases with the increase of liquefaction temperature, liquefaction time, catalyst content or liquid ratio. It is also found that the optimum condition of liquefaction for poplar is estimated as: the reaction temperature of 180 C, the reaction time of 2.5 h, liquid ratio (phenol/wood ratio) of 4.5 and catalyst content of 8%, and 4.2% residue rate could be obtained. Under the processing parameters of temperature 180 C, the reaction time of 2.5 h, liquid ratio (phenol/wood ratio) of 4 and catalyst content of 10%, the residue rate of Chinese fir can reach 5.6%.

关键词： wood liquefaction phenol residue rate liquefaction processing parameters

Identification and Evaluation of Antioxidant Activities of Bamboo Extracts

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Forestry Studies in China 2004年第2期6卷 1-5页

作者： MuJun UeharaTohru LiJianzhang FurunoTakeshi FacultyofScienceandEngineering ShimaneUniversityMatsue690-8504Japan collegeofmaterialsciencesandtechnology BeijingForestryUniversityBeijing100083P.R.China

The antioxidant activity of solvent extracts from two main bamboo species, moso bamboo (Phyllostachys pubescens) and madake bamboo (P. bambusoides) in Japan, was first evaluated by scavenging free radical of 1,1-diphenyl-2-picrylhydrazyl (DPPH), the inhibition activity for peroxidation of linoleic acid, and the reduction power. The methanol-extracts of moso bamboo culms and madake bamboo leaves presented stronger antioxidant activity compared with DPPH scavenging activity. Methanol-extract of moso bamboo culms was further fractionated by different solvents and n-butanol soluble fraction exhibited the most significant activity in the DPPH scavenging assay. The fractionation of n-butanol soluble extract was isolated by silica gel column with gradient mixture solvent of chloroform and methanol. The isolated fractions were directed by the antioxidant activity measured by scavenging the stable DPPH free radical. It was observed that most of the eluted fractions showed the antioxidative activity. Fractions acquired from elution with the mixture solvent of chloroform and methanol (10:1–5:1) showed stronger antioxidant activity than the other fractions.

关键词： bamboo extract moso bamboo antioxidant activity DPPH radical