• Journal of the Korean Wood Science and Technology
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• v.36 no.5
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• pp.42-48
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• 2008

This study was conducted to discuss the effects of hardener and extender contents on peak temperature, reaction enthalpy (${\Delta}H$), gelation time, viscosity change, and pH value in three types of UMF (urea-melamine- formaldehyde) resin with the help of perpHecT LogR meter, differential scanning calorimetry (DSC), and advanced rheometric expansion system (ARES), The results indicated that the pH value of Control A steeply decreased to 5,2 in the early stage but relatively remained constant thereafter as in Synthesis 1 and Synthesis 2, The peak temperature and time decreased as well, whereas ${\Delta}H$ and viscosity increased with the increase of hardener content. On the other hand, ${\Delta}H$ was not changed up to the extender content of 5% and then decreased with its further addition, And the pH value and peak temperature showed no change with the increase of extender content at the hardener content of 5% in three types of UMF resin, The effect of hardener content in this experiment, however, appeared more conspicuous in Control A than in the other two types of Synthesis 1 and Synthesis 2, These results might be caused by higher molecular weight with longer chains of methylene ($-CH_2-$) and methylene ($-CH_2-O-CH_2-$) ether bridges or much more branched chains in Control A.

• Journal of Forest and Environmental Science
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• v.3 no.1
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• pp.11-16
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• 1983

Two species which belong to a needle-leaf tree, three species which belong to a broad-leaved tree and three resins were selected and made into samples. They were glued in the amount of spread-$200g/m^2$, clamping pressure-$10kg/cm^2$ and room temperature during 48 hrs. This experiment was carried out to investigate results on gluing faculty tests with examining block shear strength, wood failure, tensile strength and bending strength. The result obtained may be summarized as follows. 1. Strength values of each resin made not difference, but those of each species had difference. 2. The result which Picea Koraiensis Nakai had good wood failure reveals better resin strength than wood strength. 3. Pinus Koreaiensis sieb. et Zucc. had poor tensile strength regardless of resins. 4. A broad-leaf tree, Robinia pseudoacacia Linne had good bending strength.

• Journal of the Korean Wood Science and Technology
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• v.45 no.6
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• pp.787-796
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• 2017

A low dimensional stability and poor bending strength properties were main problems in particleboard manufacturing. The objective of this research was to evaluate the effect of mixed wood species and urea-formaldehyde (UF) or urea-melamine-formaldehyde (UMF) resins on the physical and mechanical properties of three-layer particleboards. The ratio of face/core/back layer was 1 : 2 : 1. The resin content of 12% for both UF resins and UMF resins (UF/MF = 70/30% w/w) was used. The results of this study showed that the utilization of S.mahagony shaving using both UF and UMF resins caused a decrease in the thickness swelling and water absorption of the boards. Thickness swellings of particleboard made of Sengon/Sengon/Sengon (SSS), Mahogany/Mahogany/Mahogany (MMM), Sengon/Mahogany/Sengon (SMS), and Mahogany/Sengon/Mahogany (MSM) were in the range of 23%, 12~16%, 14~16%, and 13~21%, respectively. The board bonded with UMF resin demonstrated better dimensional stability than that bonded with UF resin alone. Modulus of elasticity (MOE) and modulus of rupture (MOR) of particleboards made of S. mahagony shaving in the surface layer in both MMM and MSM boards were better than those of the SSS and SMS. MOE of MMM and MSM board was in the ranges of 24,000 to $26,000kg.cm^{-2}$ and 18,000 to $21,000kg.cm^{-2}$ respectively. Meanwhile, the MOR of board was in the ranges of 200 to $240kg.cm^{-2}$ and 190 to $228kg.cm^{-2}$, respectively.

• Journal of Ocean Engineering and Technology
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• v.31 no.3
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• pp.241-247
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• 2017

Plywood, which is created by bonding an odd number of thin veneers perpendicular to the grain orientation of an adjacent layer, was developed to supplement the weak points such as contraction and expansion of conventional wood materials. With structural merits such as strength, durability, and good absorption against impact loads, plywood has been adopted as a structural material in the insulation system of a membrane type liquefied natural gas (LNG) carrier. In the present study, as an attempt to resolve recent failure problems with plywood in an LNG insulation system, conventional PF (phenolic-formaldehyde) resin plywood and its alternative MUF (melamine-urea-formaldehyde) resin bonded plywood were investigated by performing material bending tests at ambient ($20^{\circ}C$) and cryogenic ($-163^{\circ}C$) temperatures to understand the resin and grain effects on the mechanical behavior of the plywood. In addition, the failure characteristics of the plywood were investigated with regard to the grain orientation and testing temperature.

• Journal of the Korean Wood Science and Technology
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• v.43 no.4
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• pp.528-537
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• 2015

To reuse the waste bone from restaurants or butcher houses, the possibility of using waste bone powder after cooking as a filler for wood adhesives used in manufacturing plywood was investigated. Radiata pine (Pinus radiata D. Don) plywoods were manufactured by using commonly used wood adhesives such as urea-melamine formaldehyde (UMF) resin, urea-formaldehyde (UF) resin, and phenol-formaldehyde (PF) resin and the prepared fillers from cattle bone powder, pig bone powder, and seashell powder. Plywood fabricated by using cattle bone powder, pig bone powder, and seashell powder showed weaker performance in dry and wet glue-joint shear strength and wood failure than those of the plywood with wheat flour. The result showed that it was hard to use only bone powder for the replacement of wheat flour. However, the filler mixed with wheat flour and bone powders showed equivalent dry bonding strength and better water resistance than the wheat flour, indicating that bone powders mixed with wheat flour might be used for the manufacture of plywood. When bone powders were mixed with wheat flour as adhesive fillers the shell powder showed the lowest bonding properties and there was no big difference between the cattle bone powder and the pig bone powder.

• Journal of the Korean Wood Science and Technology
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• v.45 no.1
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• pp.126-138
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• 2017

This study was conducted to investigate the potential of chicken feather (CF), which is a by-product in poultry industry, as a raw material of wood adhesives. For the purpose, adhesive resins were formulated with NaOH- and $H_2SO_4$-hydrolyzed CF as well as crosslinkers, and then the properties and water resistance of the adhesive resins against hot water were measured. CF was made of mainly keratin-type protein, and no or very low content of heavy metals was detected. Hydrolysis rate of CF increased as NaOH concentration in hydrolysis solutions increased. However, in order to minimize the loss of adhesive property of protein itself by the severe hydrolysis of CF and to seek its proper hydrolysis conditions, NaOH concentrations in hydrolysis solution determined to adjust to 5%, 7.5% and 10%. In the NaOH-hydrolyzed CF, $H_2SO_4$-hydrolyzed CF as a hardener and crosslinker were added to formulate CF-based adhesive resins. Solid content of the resins ranged from 28.3% to 44.8% depending on hydrolysis conditions and type of crosslinker. Viscosity of the resins at $25^{\circ}C$ was very high. However, when the temperature of the resins was increased to $50^{\circ}C$, the viscosity decreased greatly and thus the resins could be applied as a sprayable resin. Retention rate measured to evaluate the water resistance of adhesive resins was the highest in the cured resin formulated with 5% NaOH-hydrolyzed CF and 5% $H_2SO_4$-hydrolyzed CF of 10% based on the solid weight as a hardener. Retention rate depending on crosslinkers added into adhesive resins was the highest phenol-formaldehyde (PF) followed by melamine-urea-formaldehyde (MUF) and formalin. The retention rate of CF-based adhesives formulated with 5% NaOH-hydrolyzed CF, PF and $H_2SO_4$-hydrolyzed CF of 10% and over did not differ statistically from that of commercial MUF resins. All of CF-based adhesives formulated with PF as a crosslinker and one with 5% NaOH-hydrolyzed CF of 55%, 5% $H_2SO_4$-hydrolyzed CF of 15%, and MUF of 30% on the basis of solid weight could be substituted for commercial urea-formaldehyde resins, From the results, CF can be used as a raw material of wood adhesives if hydrolyzed in proper conditions.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.580-587
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• 2017

Woodfiber insulation board can be considered as a one of the key material for low energy consumption, comfortable and safety construction of residential space because of its eco-friendly and high thermal insulation performance. This study was carried out to investigate the formaldehyde (HCHO) total volatile organic compounds (TVOC) emission properties and combustion shapes by flame test of low density fiberboards (LDFs) prepared with different adhesives. HCHO TVOC emission and combustion properties of LDFs prepared by melamine urea formaldehyde (MUF), phenol formaldehyde (PF), emulsified methylene diphenyl diisocyanate (eMDI) and latex resin adhesives were measured by desiccator method, 20 L chamber method, and flame test, respectively. As results, LDFs manufactured by MUF, eMDI and latex resin adhesives satisfied the Super $E_0$ grade of HCHO emission performance except PF resin. Furthermore, TVOC emission of all LDFs were satisfied the Korean indoor air quality standard (below $400{\mu}g/m^2{\cdot}h$). Especially, LDF with eMDI resin adhesive showed the lowest HCHO and TVOC emissivity, that $0.14mg/{\ell}$, $12{\mu}g/m^2{\cdot}h$, respectively. However, eMDI emitted the small amount ($3{\mu}g/m^2{\cdot}h$) of toluene in VOC components. In the flame test, LDF with MUF resin adhesives showed the most favorable shape after flame test compare to LDFs prepared other adhesives. Based on HCHO and TVOC emission, and combustion shapes, MUF resin adhesive may be recommended to prepare LDF for insulation purpose.

• 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.