• Journal of the Korean Wood Science and Technology
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• v.35 no.5
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• pp.67-75
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• 2007

As a part of abating the formaldehyde emission of urea-formaldehyde (UF) resin adhesive by lowering formaldehyde to urea (F/U) mole ratio, this study was conducted to investigate properties of UF resin adhesive with different F/U mole ratios. UF resin adhesives were synthesized at different F/U mole ratios of 1.6, 1.4, 1.2, and 1.0. Properties of UF resin adhesives measured were non-volatile solids content, pH level, viscosity, water tolerance, specific gravity, gel time and free formaldehyde content. In addition, a linear relationship between non-volatile solids content and sucrose concentration measured by a refractometer was established for a faster determination of the non-volatile solids content of UF resin. As F/U mole ratio was lowered, non-volatile solids content, pH, specific gravity, water tolerance, and gel time increased while free formaldehyde content and viscosity were decreased. These results suggested that the amount of free formaldehyde strongly affected the reactivity of UF resin. Lowering F/U mole ratio of UF resin as a way of abating formaldehyde emission consequently requires improving its reactivity.

• Textile Coloration and Finishing
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• v.24 no.3
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• pp.221-231
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• 2012

Rayon fabrics were treated with some commercial non-formaldehyde and low-formaldehyde resins, and then their effect on the physicochemical properties of fabrics, including formaldehyde release, tear strength, shrinkage, and wrinkle recovery, were investigated respectively. Rayons treated with non-formaldehyde resin, little formaldehyde release was observed. Considering other factors, the optimal concentration of non-formaldehyde resin was shown to be 11-13%, and curing temperature was $170{\sim}175^{\circ}C$. In case of low-formaldehyde type, 9-11% resin concentration and curing temperature of $170{\sim}180^{\circ}C$ were recommended for optimal finishing condition. The choice and combination of resins and catalysts were also important factors, and preliminary considerations before resin-finishing of rayon are also important to get much better results.

• Textile Coloration and Finishing
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• v.24 no.2
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• pp.121-130
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• 2012

Cotton fabrics were treated with some commercial non-formaldehyde and low-formaldehyde resins, and then their effect on the physicochemical properties were respectively investigated including formaldehyde release, tear strength, shrinkage, and wrinkle recovery. Formaldehyde release less than 10ppm was obtained only by non-formaldehyde resin. Considering other factors, the optimal concentration of non-formaldehyde resin was shown to be 9-11%. In case of low-formaldehyde type, 5-7% resin concentration and curing temperature of $160{\sim}170^{\circ}C$ were recommended for optimal finishing condition. The choice and combination of resins and catalysts were also important factors, and preliminary considerations before treating cotton fabrics with resins used in this study are also important to get much better results.

• Journal of the Korean Home Economics Association
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• v.25 no.1
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• pp.35-42
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• 1987

Since the 1930's, a rapid development of resin processing has contributed to making our clothing life convenient and rich. Wrinkle considered as the largest defect of cellulose fiber is generated from fixation of molecules which are divided by compression or crookedness. It can be protected by building a bridge between the molecules the joint combination of the inside of the fiber. The formaldehyde reactive resin which is used in processing resin is a chemical compound with more than 2 N-methylol or N-alkoxymethylol group and a chemical compound with N-methylol shows the property of W.W and D.P through the very complex bridge-bonding reaction under the OH group of cellulose and acid catalyst. However, if the processing is excessively carried out, resin-processed textile emits the formaldehyde when the bridge bonding agent reacts to amine type under the acid condition or the formaldehyde remains in the condition of non-reaction or the resin combinates by itself, or the methylol group of non-reactive resin is hydrolyzed due to the insufficient themomagnetic treatment.

• Journal of the Korean Wood Science and Technology
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• v.4 no.1
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• pp.28-32
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• 1976

This study was carried out to know the adaptability of barley flour, potato flour and white ash as extender and filler of urea-formaldehyde resin for plywood as a substitute material of wheat flour. The extenders and filler used at this study were extended by several groups of percentages. Shear strength, moisture contents, and specific gravities were compared among tested groups. The results obtained are summarized as follows. 1) Wet and dry shear strength of plywoods extended by 10% barley flour, 30% potato flour, and wheat flours were shown better results than non extended plywoods. 2) There was no significant difference between plywoods extended until 50% barley flours and non extended plywoods. 3) Shear strength of plywoods extended by 50% potato and 100% barley flours were shown worse result than non extended. 4) Dry and wet shear strength of plywoods extended by white ash were shown worst result. 5) The plywoods extended by potato flours were shown not only better shear strength, but also considered more profitable cost for extending.

• Journal of the Korean Wood Science and Technology
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• v.48 no.2
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• pp.136-153
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• 2020

In this paper, the influence of initial formaldehyde/urea (F/U) molar ratios on the performance of low molar ratio (1.0) urea-formaldehyde (UF) resin adhesives has been investigated. Two initial F/U molar ratios, i.e., the first and second initial molar ratios were used for the alkaline addition reaction. Three levels of the first initial F/U molar ratios (2.0, 3.0, and 4.0) and two levels of the second initial molar ratios (2.0 and 1.7) were employed to prepare a total of six UF resins with an identical final molar ratio (1.0). The basis properties, functional groups, molecular weight, crystallinity, and thermal curing properties of the UF resins were characterized in detail. Higher levels (3.0 and 4.0) of the first initial F/U molar ratio provided the UF resins with better properties (non-volatile solids content, viscosity, gelation time, pH, and specific gravity) than those of the resins prepared with the conventional level F/U molar ratio of 2.0. Statistical analysis suggested that combining the first and second initial molar ratio of 4.0 with 1.7 would result in UF resins with greater adhesion strength and lower formaldehyde emission than those of the resins prepared with other molar ratios. The results showed that higher levels of the first initial molar ratio resulted in a more branched structure, as indicated by GPC, FTIR, DSC, XRD, and greater adhesion strength than those of the other UF resins with an identical final molar ratio of 1.0.

• Journal of the Korean Wood Science and Technology
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• v.31 no.6
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• pp.83-88
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• 2003

The woodceramics are porous amorphous carbon and glassy carbon composite materials. Woodceramics attracted a lot of attention in recent years because they are environmentally friendly and because of their unique functional characteristics such as catalysis, moisture absorption, deodorization, purification, carrier for microbial activity, specific stiffness, corrosion and friction resistance, and their electromagnetic shielding capacity. In this paper, we made new products of clay-woodceramics to investigate the industrial analysis and ethylene gas adsorption for basic data of building- and packging- materials keeping fruit fresh for a long time. Clay-woodceramics were carbonized for 3 h of heating in a special furnace under a gas flow of nitrogen(15 ml/min.) from 3 layers-clay-woodparticleboard made from pallet waste wood, phenol- formaldehyde resin(hereafter PF, Non volatile content:52%, resin content 30%), and clay(10%, 20% and 30%). Carbonization temperature was 400℃, 600℃ and 800℃. Experimental results shows that the higher the carbonization temperature, the higher the fixed carbon and the lower the volatile contents. The higher the clay content, the more the ash content. The higher the carbonization temperature, the more the ethylene gas adsorption. Carbonization temperature of 800℃ gave the best reslts as same as that of white charcoal and activated carbon.(800℃-clay-woodceramic: 5.36 ppm, white charcoal: 5.66 ppm, activated carbon: 5.79 ppm) The clay contents did not make difference of ethylene gas adsoption.

• Korea-Australia Rheology Journal
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• v.20 no.2
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• pp.59-63
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• 2008

A theoretical model was developed to describe the flow behavior of a filled polymer in the packing stage of reaction injection molding and predict the residual stress distribution of thin injection-molded parts. The model predictions were compared with experiments performed for phenol-formaldehyde resin filled with wood dust and cured by urotropine. The packing stage of reaction injection molding process presents a typical example of complex non-isothermal flow combined with chemical reaction. It is shown that the time evolution of pressure distribution along the mold cavity that determines the residual stress in the final product can be described by a single 1D partial differential equation (PDE) if the rheological behavior of reacting liquid is simplistically described by the power-law approach with some approximations made for describing cure reaction and non-isothermality. In the formulation, the dimensionless time variable is defined in such a way that it includes all necessary information on the cure reaction history. Employing the routine separation of variables made possible to obtain the analytical solution for the nonlinear PDE under specific initial condition. It is shown that direct numerical solution of the PDE exactly coincides with the analytical solution. With the use of the power-law approximation that describes highly shear thinning behavior, the theoretical calculations significantly deviate from the experimental data. Bearing in mind that in the packing stage the flow is extremely slow, we employed in our theory the Newtonian law for flow of reacting liquid and described well enough the experimental data on evolution of pressure.

• Journal of the Korean Wood Science and Technology
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• v.31 no.5
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• pp.80-87
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• 2003

This research was carried out to examine physical and mechanical properties of clay-woodceramics which were carbonized for 3 hours in a special furnace from 3 layers-clay-woodparticleboard made from pallet waste wood, phenol formaldehyde resin(hereafter PF, Non volatile content 52%, resin content 30%) and clay(10%, 20% and 30%). Carbonization temperature was 400℃, 600℃ and 800℃. The results are summarized as follows: 1. The higher the carbonization temperature, the higher the dimensional shrinkage and the lower the carbonization yield ratio. But the higher the clay addition, the lower the dimensional shrinkage and the higher carbonization yield ratio. 2. The higher the carbonization temperature, the higher the water absorption and the density. The higher the clay content, the higher the density. 3. The higher the carbonization temperature, the higher the bending Modulus of Rupture and bending Modulus of Elasticity.

• Journal of the Korean Wood Science and Technology
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• v.47 no.4
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• pp.519-532
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• 2019

The objectives of this study were to evaluate the effects of shelling ratio and resin content on the properties of bamboo oriented strand board (BOSB) from betung (Dendrocalamus asper) and to determine the correlation between the results of dynamic and static bending tests. Strands were steam-treated at $126^{\circ}C$ for 1 h under 0.14 MPa pressure and followed by washing with 1% NaOH solution. Three-layer BOSB with the core layer perpendicular to the surface was formed with shelling ratios (face:core ratio) of 30:70; 40:60; 50:50; 60:40 and binded with 7% and 8% of phenol formaldehyde (PF) resin with the addition of 1% of wax. The evaluation of physical and mechanical properties of BOSB was conducted in accordance with the JIS A 5908:2003 standard and the results were compared with CSA 0437.0 standard for commercial OSB (Grade O-1). Non-destructive testing was conducted using Metriguard Model 239A Stress Wave Timer which has a wave propagation time from 1 to $9,999{\mu}s$ and a resolution of $1{\mu}s$. BOSB with 8% resin content showed better physical and mechanical properties than those with 7% resin content. The increase of the face layer ratio improved the strength of BOSB in parallel direction to the grain. The results suggested that shelling ratio of 50:50 could be used as a simple way to reduce PF resin requirements from 8% to 7% and to meet the requirements of CSA 0437.0 standard. The results of non-destructive and destructive tests showed a strong correlation, suggesting that non-destructive test can be used to estimate the bending properties of BOSB.