• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.41-50
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• 2000

Cement-bonded particleboard is being used as outdoor siding material all over the world, because this composite particularly bears a light weight, high resistance against fire, decay, and crack by cyclic freezing and thawing, anti-shock property, and strength enhancement. Construction systems are currently changing into a frame-building style and wooden houses are being constructed with prefabrication type. Therefore, they require a more durability at outdoor-exposed sides. In this study, the cement hydration property for Korean pine particle, Japanese larch particle and face- and middle layer particles (designated as PB particle below) used in Korean particleboard-manufacturing company was investigated, and the rapid manufacturing characteristics of cement-bonded particleboard by supercritical $CO_2$ curing was evaluated. Korean pine flour showed a good hydration property, however, larch flour showed a bad one. PB particle had a better hydration property than larch flour. The addition of $Na_2SiO_3$ indicated a negative effect on hydration, however, $MgCl_2$ had a positive one. Curing by supercritical $CO_2$ fluid gave a conspicuous enhancement in the performances of cement-bonded particleboards compared to conventional curing. $MgCl_2$ 3%-added PB particle had the highest properties, and $MgCl_2$ 1%-added Korean pine particle had the second class with the conditions of cement/wood ratio of 2.7, a small fraction-screened particle and supercritical curing. On the contrary, the composition of non-hammermilled or large fraction-screened particle at cement/wood ratio of 2.2 was poorer. Also, the feasibility for actual use of 3%-added, small PB particle-screened fraction was greatest of all the conventional curing treatments. Relative superiority of supercritical curing vs. conventional curing at dimensional stability was not so apparent as in strength properties. Through the thermogravimetric analysis, it was ascertained that the peak of a component $CaCO_3$ was highest, and the two weak peaks of calcium silicate hydrate and ettringite and $Ca(OH)_2$ were present in supercritical treatment. Accordingly, it was inferred that the increased formation of carbonates in board contributes to strength enhancement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.65-71
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• 2001

Absorbers such as porous materials and panels have limited absorption characteristics to some frequency bands. There is a need for absorbers with high absorption coefficients in a wide frequency ranges to make good response of room acoustics. This is almost impossible for a single absorption material. Composite absorption structure with cover, porous material. and air gap is known to have those wide frequency characteristics. In this basis. various composite absorption structures are measured and investigated as wide range absorption structures. Measurements are performed according to an international standard, ISO 354. Various surface types such as wooden slits, wood/steel perforated panels are selected as surface covers, and also various porous materials such as polyurethanes, polyesters, and glasswools are used inside the covers. Result shows that the area of void parts of surface materials is critical to high frequency absorptions, and thickness of air gaps are critical factor of the peak absorptions of low frequency bands.

• Journal of the Korea Furniture Society
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• v.14 no.1
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• pp.1-9
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• 2003

This research was carried out for packing materials and building materials to examine thylene gas adsorption and effect of keeping fruit fresh of wet formed charcoal-fiber mposite made from defibrated fiber of Pinus densiflora Sieb. et Zucc. and white charcoal from uercus variabilis Bl.(wood fiber: charcoal=8:2, 6:4, 4:6, 2:8), with/without phenol formaldehyde resin(PF, Non volatile content:$52\%$, resin content $1,3,5\%$). The results are summarized as follows: 1. The higher the charcoal content, the more the ethylene gas adsorption. At the same mixing ratio of fiber to charcoal, $\#100-200$ of charcoal particle size gave the better reslts than $\#60-100$. 2. Adding PF into the charcoal fiber composite decreased the capacity of ethylene gas adsorption but there was no significant difference until $5\%$ adding amount of PF. 3. For keeping fruit fresh for a long time, Charcoal fiber composite was $66\%$ longer than control. The higher the white charcoal content, the longer fresh time.

• Polymer(Korea)
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• v.37 no.5
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• pp.613-617
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• 2013

The effects of nano size kenaf cellulose fiber on mechanical property of polypropylene (PP) composite were investigated. The addition of nano-kenaf in place of natural kenaf showed higher tensile strength, flexural strength, impact strength, and heat deflection temperature compared to the natural kenaf filled PP composite, while it shows lower melt flow index, elongation%, and flexural modulus. These seemed to be due to the increased surface area of nano-kenaf fiber contacting PP matrix and reduced impurities such as volatile extractives on the fiber surface.

• Advances in materials Research
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• v.12 no.2
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• pp.119-131
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• 2023

The development of sustainable composites materials, from recycled polymeric materials and waste from the wood industry and stone processing, allows reducing the volume of these by-products, minimizing impacts on health and the environment. Nowadays, Polypropylene (PP) is the most recycled polymer in industry, while the furniture industry has increasingly used timber felled from sustainable forest plantations as a eucalypt. The powder tailing from the ornamental stone extraction and processing industry is commonly disposed of in the environment without previous treatment. Thus, the technological option for the development of composite materials presents itself as a sustainable alternative for processing and manufacturing industries, enabling the development of new materials with special technical features. The results showed that powder granite particles may be incorporated into the polypropylene matrix associated with short eucalyptus fibres forming green hybrid composites with potential application in structural engineering, such as transport and civil construction industries.

• Journal of the Korean Wood Science and Technology
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• v.12 no.3
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• pp.25-34
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• 1984

This experiment was carried out to investigate the effects of monosaccharides extracted by saturated portland cement solution on the cement setting in comparision with the inhibitory index (I) of each lignocellulosic-cement system. The wood species which have been widely reforested in Korea, Populus alba-grandulosa, Larix leptolepis, Abies holophylla, Pinus koraiensis, Pinus rigida, Pinus densiflora and agricultural wastes of rice husk and rice stalk were used at this study. The wood meal, 0.50g on dry weight basis, through 0.83 mm(20 mesh) and retained on 0.35mm (40 mesh) screen was extracted by 25 ml saturated portland cement solution and the pH of saturated portland cement solution Was 12.7. To eliminate cation exsisting in the extracted solution, the cation exchange column was used (Fig. 4). Afterwards the extracted monosaccharides were reduced into alditols with sodium borohydride and analyzed by the gas-liquid chromatography for xylan, mannan, arabinan, galactan, gluean. The heat of cement hydration for lignocellulosic-cement system was measured in Dewar flask (Fig. 2). And then the inhibitory indices were calculated from maximum hydration temperature, time and maximum slops of hydration curve of ligno cellulosic-cement systems. The results obtained were as follows; (1) The inhibitory index of pines-Pinus rigida (I=29.33) and Pinus densiflora (I=35.76), were lower than that of poplar-Populus alba-glandulosa (I=41.48), and the index of Larix ieptoiepis (I=73.00) was the highest among eight lignocellulosic-cement systems, and accordingly both Pinus rigida and Pinus des(flora were seemed to be good wood species for wood-cement composite manufacture. (2) In case of Pinus rigida, the inhibitory index was 29.33 and the ratio of the hexoses to the pemoses was 6.04 and in case of Larix leptolepis, the index and the ratio were 73.00 and 35.19, respectively. Therefore the inhibitory index increased with increasing the ratios of the hexoses to the pentoses. (3) The richer amount of xylose and mannose in species caused decreasing the slops of the hydration curve of the lignocellulosic-cement system, prohahly due to the chemical adsorption of the acetyl groups in the hemicellulose on the surface of cement grains. (4) The amoun of xylose and mannose were significant to the inhibitory index of each lignocellulosic-cement system but any specific relation between the amount of glucose and inhibitory index was not found.

• Journal of the Korean Wood Science and Technology
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• v.39 no.3
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• pp.197-205
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• 2011

Cellulose nanofibrils (CNF) with 50~100 nm diameter were manufactured from micro-size cellulose by an application of a high-pressure homogenizer at 1,400 bar. High strength nanopapers were prepared over a filter paper by a vacuum filtration from CNF suspension. After reinforcing and dispersing CNF suspension, hydroxypropyl cellulose (HPC) and polyvinyl alcohol (PVA)-based composites were tailored by solvent- and film-casting methods, respectively. After 2, 4, 6 and 8 passes through high-pressure homogenizer, the tensile strength of the nanopapers were extremely high and increased linearly depending upon the pass number. Chemical modification of 1H, 1H, 2H, 2H-perfluorodecyl-triethoxysilane (PFDTES) on the nanopapers significantly increased the mechanical strength and water repellency. The reinforcement of 1, 3, and 5 wt% CNF to HPC and PVA resins also improved the mechanical properties of the both composites.

• International Journal of Industrial Entomology and Biomaterials
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• v.26 no.2
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• pp.81-88
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• 2013

Wet-spun silk fibers have attracted the attention of many researchers because of 1) the unique properties of silk as a biomaterial, including good biocompatibility and cyto-compatability and 2) the various methods available to control the structure and properties of the fiber. Cellulose nanofibrils (CNFs) have typically been used as a reinforcing material for natural and synthetic polymers. In this study, CNF-embedded silk fibroin (SF) nanocomposite fibers were prepared for the first time. The effects of CNF content on the rheology of the dope solution and the characteristics of wet-spun CNF/SF composite fibers were also examined. A 5% SF formic acid solution that contained no CNFs showed nearly Newtonian fluid behavior, with slight shear thinning. However, after the addition of 1% CNFs, the viscosity of the dope solution increased significantly, and apparent shear thinning was observed. The maximum draw ratio of the CNF/SF composite fibers decreased as the CNF content increased. Interestingly, the crystallinity index for the silk in the CNF/SF fibers was sequentially reduced as the CNF content was increased. This phenomenon may be due to the fact that the CNFs prevent ${\beta}$-sheet crystallization of the SF by elimination of formic acid from the dope solution during the coagulation process. The CNF/SF composite fibers displayed a relatively smooth surface with stripes, at low magnification (${\times}500$). However, a rugged nanoscale surface was observed at high magnification (${\times}10,000$), and the surface roughness increased with the CNF content.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.11a
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• pp.168-182
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• 2001

A new concept of stock preparation for the increase of bending stiffness in paper and board was proposed. The 'stiff' fibers, which were mechanically not treated or treated slightly to remove fiber curls, were combined with extensively refined fibers (ERF) to produce higher stiffness papers than those where the whole fibers were refined. The combination of 'stiff' fibers and extensively refined fibers produced higher stiffness at the same tensile strength than the control furnish, in which all the fibers are refined together. In this concept, the fibers from recycled papers could be as much useful as the virgin fibers as long as they are stiff enough or they can produce highly bondable fiber fractions by extensive refining. Use of the concept in real paper mill needs considerations such as increase of refining energy, slower drainage, and added drying burden, but savings of wood fibers, utilization of more recycled fibers, and increase of physical properties may offset the negative concerns. The success of this concept implementation in mills, therefore, depends on the wood fiber market around the mills and the proper decision making for the papermakers about how to apply this concept.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.4
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• pp.31-39
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• 2011

One of the main drawbacks of wood fibers based composite materials are their tendency to swell due to moisture uptake in wet and moist environments. The main contribution to the hygroexpansion usually comes from the hydrophilic wood fibers. Recent trend toward the high speed printing, copying, and precision converting precesses demands a high level of dimensional stability under various environmental conditions. The purpose of this study was to investigate the dimensional stability of softwood bleached kraft pulp handsheets depending on wet pressing conditions. By increasing the number of wet pressing, dimensional stability was decreased because of increased fiber-to-fiber bonding. Hygroexpansion of handsheets had a linear relationship with the relative bonded area and equilibrium moisture contents. Dip elongation was decreased when the number of wet pressing was increased because of increased fiber-to-fiber bonding to resist low load in water.