• Journal of the Korean Wood Science and Technology
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• v.39 no.1
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• pp.21-27
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• 2011

This study was carried out to examine properties of water resistant plywood by using serum protein adhesive which is natural, environment-friendly and human-friendly. For the preparation of the serum protein adhesive, pig blood from slaughterhouse was centrifuged and serum was separated from corpuscles and concentrated to 30% by dry weight basis. This concentrated serum protein was modified with PF resin (50% NVC) with the ratio of 9 : 2.5. Plywood made by this modified serum protein gave 1.21 N/$mm^2$ of dry bonding strength, 0.80 N/$mm^2$ of wet boil bonding strength, 0% of cyclic delamination test value, and 0.025 ppm of HCHO emission, which met the excellent super $E_0$ grade and water resistant plywood.

• Journal of the Korean Wood Science and Technology
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• v.40 no.2
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• pp.110-122
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• 2012

This study investigated the effects of layered clay on the thermal curing behavior and tensile properties of resole phenol-formaldehyde (PF) resin/clay/cellulose nanocomposites. The thermal curing behavior of the nanocomposite was characterized using conventional differential scanning calorimetry (DSC) and temperature modulated (TMDSC). The addition of clay was found to accelerate resin curing, as measured by peak temperature ($T_p$) and heat of reaction (${\Delta}H$) of the nanocomposite’ curing reaction increasing clay addition decreased $T_p$ with a minimum at 3~5% clay. However, the reversing heat flow and heat capacity showed that the clay addition up to 3% delayed the vitrification process of the resole PF resin in the nanocomposite, indicating an inhibition effect of the clay on curing in the later stages of the reaction. Three different methods were employed to determineactivation energies for the curing reaction of the nanocomposite. Both the Ozawa and Kissinger methods showed the lowest activation energy (E) at 3% clay content. Using the isoconversional method, the activation energy ($E_{\alpha}$) as a function of the degree of conversion was measured and showed that as the degree of cure increased, the $E_{\alpha}$ showed a gradual decrease, and gave the lowest value at 3% nanoclay. The addition of clay improved the tensile strengths of the nanocomposites, although a slight decrease in the elongation at break was observed as the clay content increased. These results demonstrated that the addition of clay to resole PF resins accelerate the curing behavior of the nanocomposites with an optimum level of 3% clay based on the balance between the cure kinetics and tensile properties.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.171-176
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• 2013

The need of volatile organic compound (VOC) free coating material has been increased to solve environmental problems such as the global warming. Nowadays, about 70~80% of coating materials used in the worldwide are a liquid type. Therefore, the development of non-solvent coating material that can minimize VOCs emissions is necessary to solve the global warming problem. In this study, acrylic monomers were added to develop non-solvent paints in order to improve disadvantages of the poor adhesion of a conventional phenolic resin caused by acidification. As a result, the blend resins of 2.818 Mpa phenol- formaldehyde resin/poly methyl methacrylate (PE/PMMA) has the best properties and performances for the adhesives.

• Journal of the Korean Wood Science and Technology
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• v.32 no.3
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• pp.25-32
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• 2004

This research work explored physical and mechanical properties of impregnated sawdust boards from three softwood species (P, densifora, L. kaemferi, and P. koraiensis) with phenol-formaldehyde (PF) resin by various vacuum treatment methods of combining pressure, vacuum, and ultrasonic waves. Simultaneous vacuum and ultrasonic wave treatments with no pressure resulted in the greatest increase in resin content, density, dimensional changes (thickness and length), bending strength, and hardness of impregnated board. This result seemed to be attributed to the ultrasonic wave treatment.

• 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.

• Journal of the Korean Wood Science and Technology
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• v.48 no.5
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• pp.722-731
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• 2020

The purpose of this research is to determine the efficiency of impregnation using phenol formaldehyde resin to enhance Falcataria wood's stability and better mechanical properties. Impregnation process was carried out after moisture content stabilized at 12% on samples with a dimension of 20 mm × 20 mm × 300 mm at various concentrations and pressure time. Dimensional stability was evaluated by thickness swelling (TS) and anti-swelling efficiency (ASE) and the young's modulus was conducted according to BS 573. The mechanical properties and dimensional stability of impregnated wood were evaluated. Dimensional stability and mechanical properties of Falcataria wood were successfully increased after impregnation. PF impregnation can improve the mechanical properties and the density from 0.26 g/㎤ to 0.30 g/㎤ even with only 10% of weight percent grain. Dimensional stability increases with increasing resin concentration and time pressure. The highest increase in mechanical properties was found at a higher concentration of PF. The penetration of PF into the wood's cell darkens the color of impregnated wood.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.599-612
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• 2017

Human hair (HH) is produced as a waste from beauty parlor and barbershop. HH-based adhesives were formulated with NaOH-hydrolyzed HH, $H_2SO_4$-hydrolyzed chicken blood (CB) and PF as a crosslinking agent. Physicochemical properties and retention rate against hot water of the adhesives were measured to investigate the potential of HH as a raw material of wood adhesives. HH was composed of keratin-type protein of 80% and over. Ash of less than 0.1% was contained in HH. Among the amino acids included in HH, glutamic acid showed the highest content, followed by cysteine, serine, arginine and threonine. Solid content of the adhesives ranged from 33.2% to 41.8% depending on hydrolysis conditions of HH and PF type. Viscosity at $25^{\circ}C$ ranged from 300 to $600mPa{\cdot}s$ resulting in a sprayable adhesive. Retention rate against hot water measured to evaluate the water resistance of adhesives was the highest in the cured resin formulated with 5% NaOH-hydrolyzed HH and 5% $H_2SO_4$-hydrolyzed CB. Meanwhile, the molar ratio of formaldehyde to phenol in PF did not have a significant impact on the retention rate of HH-based adhesives. When the retention rates of HH-based adhesives were compared to those of conventional wood adhesive resins used for the production of wood-based panels extensively, HH-based adhesives formulated with 30 wt% PF showed lower retention rate than commercial urea-formaldehyde resin. However, when PF content was increased to 35 wt%, the retention rate greatly increased and approached to that of commercial melamine-urea-formaldehyde resin. Except for the results mentioned above, the analysis of economic feasibility suggests that HH-based adhesives can be used for the production of wood-based panels if HH is hydrolyzed in proper conditions and then the HH-based adhesives are formulated by the HH hydrolyzates with 35 wt% PF.

• Journal of the Korean Wood Science and Technology
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• v.26 no.1
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• pp.14-18
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• 1998

A low density polyethylene(LDPE) was examined as an additive in phenol-formaldehyde(PF) resin adhesive for bonding radiata pine plywood. The LDPE was supplied by the commercial manufacturer. The LDPE was compared to a commercial filler commonly used in structural plywood adhesives in the United States. The adhesive mixes were made by following the recommended procedure of Georgia-Pacific Resins Inc.. using plywood-type PF resin. A total of 48 three-ply plywoods. 6.3 mm nominal thickness and 30 by 30 em in size, were made at two press times (4 and 5 min). two press temperatures (150 and $160^{\circ}C$) and 30 minute assembly times for four adhesive mixing types. Evaluations of the LDPE addition were carried out by performance tension shear tests after two cycle boil aging tests on plywood per the U.S. Product Standard PS I-83. After accelerated-aging tests. plywoods were exhibited no delamination. The test results included tension shear strength and estimated wood failure values. The plywood test results support the use of polyethylene as an additive in plywood adhesives.

• Textile Coloration and Finishing
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• v.5 no.4
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• pp.79-91
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• 1993

The purpose of this study is to prepare the newer, more comfortable of urea-formaldehyde resin finished fabrics. The methods of this study are by making examinations and comparisons the relations between the thickness, fabrics counts, weight, moisture regain and crease recovery of cotton and viscose rayon fabrics caused by condition of urea-formaldehyde resin finishing and warm retaining ability and warm-cool sense. The analytic results of thermal character in state of fabrics material finished with urea-formaldehyde are as follows: 1. The warm retaining ability has no correlation with mixing ratio of resin but the increase of the warm retaining ability has correlation with the increase of concentration of urea-formaldehyde resin. 2. The result pf multiple regression analysis for effect of physical property according to the concentration of resin to the warm retaining ability revealed as below. As the weight, thickness and density increase and moisture regain decreases, the warm retaining ability increases. 3. The qmax value has no correlation with mixing ratio of resin but the increase of the qmax value has correlation with the increase of resin concentration. In the end, the effect of it promotes cool sense. 4. The result of multiple regression analysis for effect of physical property according to the concentration of resin to the qmax value revealed as below. As he weight and thickness increase, the qmax value decrease. But, as the density and crease recovery increase, the qmax value increase.

• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.27-35
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• 2001

Four different sources of wood-fibers from Eucalyptus, Italian poplar, hemlock, and mixed species fibers were used to study the influence of their fiber characteristics on the performance of medium density fiberboard (MDF) panels bonded with both urea-formaldehyde (UF) and phenol-formaldehyde (PF) adhesives. Included fiber characteristics were fiber length, size distribution, bulk density, and acidity. Physical and mechanical properties of MDF panels manufactured by dry process using these different fibers were determined for the comparison of board performance. Two hardwood species had a large fraction of short fibers resulting in a higher bulk density while very long hemlock fibers had lower bulk density. Fiber acidity was revealed to strongly affect the internal bond (IB) strength of MDF panels bonded with UF resins. MDF panels made from mixed species fibers showed highest IB strength of all panels prepared. UF-bonded MDF panels showed poor dimensional stability. In conclusion, the present study showed that wood-fiber characteristics such as fiber length, bulk density, and acidity affect the performance of MDF boards, and also suggested that fiber characteristics be considered for MDF panel manufacture.