• Journal of the Korean Wood Science and Technology
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• 제37권6호
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• pp.566-577
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• 2009

실내에서 일어나는 목재의 표면 열화특성을 재색, 화학적 및 해부학적 변화 차원에서 분석하였다. 실험대상으로는 실내에서 장기간 보관중인 삼나무 목제품을 사용하였다. 실내 보존 초기에는 황색도와 적색도가 급격히 변하였고 5년 사이에 백색도의 감소가 두드러졌다. 화학성분의 분석결과 셀룰로오스, 헤미셀룰로오스, 리그닌 성분 모두 감소하였으나 리그닌의 감소가 더 컸다. 현미경 관찰 결과 5년이 경과한 목제품에서는 목재표면에서 2~3개 층에서 리그닌이 분해되어 중간층이 분리되었다. 실내 환경조건에서 발생되는 표면 열화 특성은 야외에서 발생되는 표면열화 특성과 매우 유사하였으나 그 정도는 미약하였다.

• Journal of the Korean Wood Science and Technology
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• 제49권5호
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• pp.453-461
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• 2021

In wood-based composite panels, low-molar ratio (LMR) urea-formaldehyde (UF) resins usually result in reduced formaldehyde emission (FE) at the expense of poor adhesion. However, the FE and adhesion of medium-density fiberboard (MDF) bonded with LMR UF resins were both improved in this study. The modified LMR UF resins with transition metal ion-modified bentonite (TMI-BNT) nanoclay simultaneously improved the FE and adhesion of MDF panels. The modified LMR UF resins with 5% TMI-BNT resulted in a 37.1% FE reduction and 102.6% increase in the internal bonding (IB) strength of MDF panels. Furthermore, thickness swelling and water absorption also significantly decreased to 13.0% and 24.9%, respectively. These results imply that TMI-BNT modification of LMR UF resins could enhance the formation of a three-dimensional network rather than crystalline domains, resulting in improved cohesion.

• Journal of the Korean Wood Science and Technology
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• 제47권5호
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• pp.567-578
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• 2019

A common problem with fast-growing hardwoods is dimensional instability that limits use of their wood. In this study, we investigated the effects of pre-drying methods, temperatures, and heating duration on the specific gravity, water absorption, and dimensional stability of three tropical fast-growing hardwoods, jabon (Neolamarckia cadamba Roxb.), sengon (Falcataria moluccana Miq.), and mangium (Acacia mangium Willd.). Wood samples were pre-dried by two methods (fan and oven at $40^{\circ}C$), and heat treatments were performed at three temperatures (120, 150, and $180^{\circ}C$) for two different time periods (2 and 6 hours). The specific gravity, water absorption, dimensional stability, and structural changes of the samples were evaluated. The results revealed that heat treatments slightly reduced the specific gravity of all three wood species. In addition, the heat treatments reduced water absorption and significantly improved dimensional stability of the samples. Oven pre-drying followed by heat treatment at $180^{\circ}C$ for 6 hours resulted in good physical improvement of jabon and sengon wood. Fan pre-drying followed by heat treatment at $180^{\circ}C$ for 2 hours improved the physical properties of mangium wood. The heat treatment shows a promising technique for improving the physical characteristic of fast growing hardwoods.

• Journal of the Korean Wood Science and Technology
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• 제25권1호
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• pp.56-64
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• 1997

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 ${\beta}$-cyanoethyl ($-CH_2-CH_2$-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 $2250cm^{-1}$, 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.

• 펄프종이기술
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• 제45권2호
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• pp.33-40
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• 2013

Powdered additive or organic filler is used to improve paperboard thickness and to reduce drying energy consumption in the Korean paperboard industry. In a previous study, we identified alternative non-lignocellulosic resources to wood powder, specifically brewers grain and oil palm frond powders, and verified that these materials had the same functionality as wood powder. The main drawback of the use of such additives, including both lignocellulosic and non-lignocellulosic resources, is the deterioration in paperboard strengths. Therefore, we carried out a basic study on the surface modification of brewers grain and oil palm frond powders to improve the strengths of paperboard. Surface modification was performed using various types of cationic and oxidized starches. The streaming current and zeta-potential of the two non-lignocellulosic powders were measured and CLSM images were taken to assess the surface modification.

• Journal of the Korean Wood Science and Technology
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• 제39권2호
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• pp.148-155
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• 2011

Thermal treatment techniques are used for modifying wood and wood-based materials to improve dimensional stability and hygroscopicity. This study investigated the effects of press pressure and temperature on density, vertical density profile, thickness swelling and surface hardness of eucalyptus wood boards. The experimental wood boards were prepared from Turkish River Gum ($Eucalyptus$ $camaldulensis$ Dehn.). The surface hardness value increased with increasing press pressure in the treated groups. The application of a higher pressure at the same temperature level increased the amount of swelling of wood. It means that it is not needed for application of higher pressure to enhance the dimensional stability of wood. It is expected that it is possible to produce increased hardness, dimensional stability and durability by application of hot pressing treatment. This research showed that different press pressure and temperature values should be used to improve the performance properties of eucalyptus wood so that the end-use of the wood materials could be expanded.

• Journal of the Korean Wood Science and Technology
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• 제41권3호
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• pp.187-200
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• 2013

본 연구에서는 목재보존제의 최근 국제적 동향 중, 비 구리계 약제를 중심으로 조사되었다. 최근의 목재보존제 연구 분야에서 다루어지는 비 구리계 약제로는 환경친화적 수용성약제 성분의 대표적인 붕소계 화합물이 가장 많았고, 자연에서 얻어지는 천연물질을 이용한 약제, 화학처리목재, pyrethroid계 방충제 등이 포함되었다. 인축 및 환경에 대한 사용안전성이 고려된 약제들이 주 연구대상이 되는 경향이 있었다. 붕소의 경우에는 옥외 사용 시 물에 대한 용탈성을 개선하기 위하여 다양한 고분자 등의 물질을 도입하여 정착성을 높이고자 하는 연구들이 주요 이슈였다. 또한 의학 분야에서 많이 다루어지던 천연물질이 목재보존제로써 사용하고자 하는 시도와 치수안정성을 목적으로 개발되었던 아세틸화 목재와 같은 화학수식목재에 대한 옥외 사용 시도가 눈에 띄게 증가된 경향을 나타내었다.

• Journal of the Korean Wood Science and Technology
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• 제46권4호
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• pp.368-379
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• 2018

Objective of this work is to study the effects of a saline solution used to pretreat lignocellulosic material derived from champak timber. The native lignocellulosic solids, in powder form, were mixed with saline water solutions of three different concentrations and maintained for 2 weeks without stirring. The treated solids were washed, recovered, and then dried under sunlight. The substrates were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The crystallinity (CrI), lateral order index (LOI), total crystallinity index (TCI), and surface morphologies of all the samples were determined. The treated biomass structures were compared with controls. The data show that the structures of all the treated substrates changed, as indicated by CrI. CrI of the treated substrates decreased significantly compared with that of the original wood, as did LOI and TCI quantities, whereas the HBI parameter increased. The results indicate that the saline water pretreatment modified the wood samples.

• Journal of the Korean Wood Science and Technology
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• 제41권2호
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• pp.123-133
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• 2013

This paper presents experimental and numerical tests on a recently developed timber column concealed base joint. This joint was designed to replace the wood-wood connection found in the post-and-beam structure of Hanok, the traditional Korean timber house. The use of metallic connectors provides an increased ductility and energy dissipation for a better performance under reversed loading, especially seismic. In this study, we investigate the performance of the joint under pseudo-static reversed cyclic moment loading through the study of its ductility and energy dissipation. We first perform experimental tests. Results show that the failure occurs in the metallic connector itself because of stress concentrations, while no brittle fracture of wood occur. Subsequent numerical simulations using a refined finite element model confirm these conclusions. Then, using a practical modification of the joint configuration with limited visual impact, we improve the ductility and energy dissipation of the joint while retaining a same level of rotational strength as the originally designed configuration. We conclude that the joint has a satisfying behavior under reversed moment loading for use in earthquake resistant timber structure in low to moderate seismicity areas like Korea.

• Journal of the Korean Wood Science and Technology
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• 제49권3호
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• pp.226-233
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• 2021

This article aimed at thermally treating and charactering the Eucalyptus grandis wood under three different temperatures. For this, pristine eucalypt samples were treated by heating in a laboratory oven at 160 ℃, 200 ℃ and 240 ℃, always for 2 h. Treatment parameters (based on weight percentage loss and specific gravity), as well as mechanical (by hardness tests), chemical (by infrared spectroscopy), thermal (by thermogravimetry), and colorimetric (by CIELab method) features were evaluated. Compared to the pristine ones, the treated woods have there was a drop in apparent density at 12 % and consecutively greater thermal stability which is probably related to a previous partial degradation of some major amorphous components (namely cellulose, hemicellulose and lignin), as suggested by the treatment parameters and infrared spectra. Besides of that, the higher the temperature treatment, the higher the loss in surface hardness and the higher the colour darkening.