• Journal of the Korea Furniture Society
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• v.12 no.2
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• pp.29-38
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• 2001

This study was carried out to develope a new process of flattening bamboo pieces(3 months old) by two steps of utilizing microwave oven and hot press. Internode bamboo pieces were impregnated with low molecular weight phenol formaldehyde resin (PF) under vacuum of 76 cmHg, heated in a household microwave oven in 1 minute, pressed on the temperature of $145^{\circ}C$ by the hot press for 10 minute, and then cooled by the cold press in their flattened form. The physical and mechanical . Properties of compressed flattened bamboo were as follows: 1) PF1(Mw:427) and PF2(Mw:246) sol. met the success of flattening of internode bamboo pieces in both of P. bambusoides and P. nigra var. PF2 showed the more plasticity to flatten the bamboo than PFI. The PF2 sol. with low molecular weight(Mw:246) gave the more weight gain than that of PF1 in the equal concentration. PF1 of 5% (NVC) and PF2 of 10% (NVC) sol. gave the best result for physical and mechanical properties and from a economical view point. 2) The PFI of 5% (NVC) sol. with low molecular weight decreased the water absorption of 62-63% and increased the bending strength (MaR) of 80-90%, compression strength of 43-54%. 3) The PF2 of 10% (NVC) sol. with low molecular weight decreased the water absorption of 56-57% and increased the bending strength (MaR) of 64-86%, compression strength of 39-63%.

• 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.28 no.2
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• pp.25-31
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• 2000

Low-density polyethylene (LDPE) powder was investigated as a hydrophobic additive component in particleboard (PB). PBs were manufactured using southern pine particles with a liquid phenolic resin binder at two press temperatures. LDPE at three application rates was used. PBs were tested for physical properties and water soak dimensional stability per the procedure ASTM D 1037. The results indicated that as the LDPE addition level and hot-press temperature were increased, the panel water absorption and thickness swell values decreased. However, the panel's physical properties were affected negatively by increased LDPE application rates. These results indicated that LDPE could be used only in limited amounts to improve the panel's water soak dimensional properties.

• Journal of the Korean Wood Science and Technology
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• v.32 no.6
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• pp.57-66
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• 2004

To study the efficient usage of small diameter logs and woods containing defects such as knots, slope of the grain and decay, six types of finger-jointed woods with various finger profiles were made of poplar, pine and oak with different density. We investigated the effect of finger profile on static bending strength performances of finger-jointed woods. The efficiency of bending MOE, MOR and deflection showed the highest value in poplar finger-jointed wood with the lowest density of three species, and the lowest value in oak finger-jointed wood with the highest density of three species. The values markedly decreased with increasing finger pitch for finger-jointed wood glued with polyvinyl acetate (PVAc) resin for all tested species, whereas for the finger-jointed wood glued with resorcinol-phenol formaldehyde (RPF) resin, the influence of finger pitch on the efficiency of MOE was not found in all tested species, and those on the efficiency of MOR and deflection indicated the same trend as finger-jointed wood glued with PVAc resin in the case of pine and oak finger-jointed wood with higher densities. It was found that the values tended to decrease with increasing density of species on the whole and the desirable finger pitches were L (6.8 mm) for poplar, M (4.4 mm) for pine and S (3.5 mm) for oak in a view of economy. For finger-jointed wood glued with PVAc resin, the fitness between a tip and a root width of a pair of fingers δ of 0.5 mm indicated the highest efficiency of MOE for all species. And, the influence of δ on MOR was only found in oak finger-jointed wood glued with RPF resin and the desirable δ value for oak was 0.1 mm. However, it was found that the influence of δ on the strength performance was very small.

• 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 Applied Science and Technology
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• v.33 no.1
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• pp.168-175
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• 2016

The surface of glass fiber bundle was modified with functionalized silanes and phenolic resin to improve the tensile strength as well as the adhesion of glass fiber to matrix phenolic resin. The surface modification of reinforcing glass fiber can play a significant role in controlling whole composite characteristics. We applied surface modification of glass fiber with two different functionalized silanes, such as glycidyltrimethoxysilane(G-silane) and aminopropyltriethoxysilane (A-silane), and phenol formaldehyde(PF) resin in one pot or separated process under different coating compositions and temperatures. Thermal treatment temperature is very important factor to improve the mechanical properties of modified glass fiber. Modified glass fiber bundle treated at $170^{\circ}C$ showed the highest tensile strength of $10.05g_f/D$. Surface analyses by scanning electron microscope(SEM) and FT-IR spectroscopy were used to characterize the surface coatings on glass fiber bundles. Mechanical property changes as functions of treatment conditions and coupling agent types were also explained.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.767-771
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• 1999

Poly(ester-imide)(PEI) for the electrical insulation coating was synthesized and evaluated with one-step method as well as two-step method. For the synthesis of poly(ester-imide), imide repeat unit of N,N'-(4,4'-diphenylmethane) bistrimellitimide(DID) was initially made from trimellitic anhydride(TMA) and methylene dianiline(MDA), followed by the second stage reaction of esterification. One-step reaction was performed by reaction of TMA, MDA, dimethyl terephthalate(DMT), ethylene glycol(EG), and 1,3,5-tris-(2-hydroxy ethyl) isocyanurate(THEIC) in m-cresol solvent at a time. The synthesized poly(ester-imide) was cured with xylene, P-5030K(phenol-formaldehyde resin), TK-8(TDI type blocked polyisocyanate) and tetrapropyltitanate(TPT). It was found that the content of hydroxyl group, amount of DMT, and imide repeat unit played important role for the properties of electrical insulation coating film.

• Journal of the Korean Wood Science and Technology
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• v.45 no.3
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• pp.243-249
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• 2017

This study was performed to find out the optimum adhesive conditions on manufacturing a cross-laminated timber (hereinafter CLT) with using domestic Korean Pine (Pinus koraiensis). The adhesive conditions including a applied amount of the glue and a Pressure are the one of the most important key factors on establishing CLT production process. The shear strength was examined with differing the adhesive conditions while using Phenol Resorcinol Formaldehyde Resin Adhesive (PRF resin). The optimum adhesive conditions was confirmed to be: glue spread of $250g/m^2$ and Pressure of 0.8 MPa respectively. The grain directions of glued specimens were also considered, perpendicularly bonded and parallelly bonded groups. Shear strength of the former group showed lower values than the latter group which is considered to be the effect of a rolling shear. Meanwhile the shear strength of both group satisfied the Korean Standard (KS F 3021) and the European Standard (EN 14080 and EN 16351). The results derived from this study can be used as the basic data for manufacturing the CLT with domestic Korean Pine. And additional researches for the other species including domestic Korean Larch and Pitch Pine is also now being performed.

• Journal of the Korean Electrochemical Society
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• v.2 no.3
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• pp.134-137
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• 1999

The polyacenic semiconductor material (PAS) electrode prepared by the pyrolytic treatment of phenol-formaldehyde resin is one of useful electrodes. As an anode material of lithium rechargeable batteries, amorphous carbon materials have been studied extensively because of their high electrochemcal performance and cyclicability. Carbon materials do not lead to the formation of lithium dendrite which is one of the most serious problems in applying Li-based materials to an electrode of batteries. The polyacene materials prepared from phenol resin at relatively low temperatures $(550\~750^{\circ}C)$ show a highly Li\doped state up to $C_2Li$ state without liberation of Li cluster. We prepared each polyacene materials at various temperature and investigated electro- chemical properties. We tried to change the mole ratio of [H]/[C] which is $0.24\~0.4$ range. Considering of electrochemical properties of PAS material, the PAS material is one of the most suitable materials for electrodes of a polymer battery.

• 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.