• Journal of the Korean Wood Science and Technology
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• v.26 no.4
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• pp.43-49
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• 1998

The availability of large quantities of waste woods provides an impetus for investigating woody biomass potential uses. Polyurethane (PU) foams are prepared with reacting isocyanates and polyols, and are used. in various industry fields. Thus, lignocellulosic waste raw-materials are proposed as replacement for synthetic polyol to PU foam formulation. In this study PU foams were manufactured from liquefied woods, methanediisocyanate(MDI), catalyst, foaming stabilizer, and viscosity aids. The polyol content, isocyanate.hydroxyl group (NCO/OH) ratio, and water content were varied to evaluate their effects on the foaming and water absorption of the PU foams. Less than 400 Molecular weight. of polyethylene glycol(PEG) and 1 to 3 solvent to woody raw-material ratio were desirable for liquefying woody materials. Liquefying rate was increased with more than 3 % addition of inorganic and organic catalysts and raising reaction temperature more than $150^{\circ}C$. Addition of starch enhanced liquefying of woody materials. Fourty percents of starch resulted in about 90% liquefying rates. Foaming rates were increased with increasing moisture contents of liquefied wood. Moisture contents of 0.6% resulted in 5 time-foaming rates, and seven percents of moisture contents more than 30 time-foaming rates. But, an increase in water content may result in a decrease in cross-links between wood polyol and isocyanate, because the NCO/OH ratio is constant. Increasing moisture contents have significantly decreased density of PU foams. The optimum water content should be about 2.5% or less in this adopted condition.

• Elastomers and Composites
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• v.35 no.4
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• pp.296-302
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• 2000

The surfaces of injection and pressure-molded sheets of poly(ethylene-covulylacetate)(EVA) foams used for shoe mid-sole were treated with low temperature plasma to improve adhesion with a water-based polyurethane adhesives. Several experimental variables were considered, such as radio frequency power, treating time, type of gas. gas flow, and distance between electrode and sample. The modificated surface by plasma treatment were characterized using contact angle meter, scanning electron microscopy(SEM), universal testing machine(UTM). Adhesion was tested by T-peel tests of treated EVA foams/polyurethane adhesive joints. The treatment in the low temperature plasma produced a noticeable decrease in contact angle. The peel strength of EVA foams treated with plasma was increased with plasma treating time, and gas flow.

• KSBB Journal
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• v.18 no.5
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• pp.412-417
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• 2003

We first investigated basic characteristics of reticulated polyurethane (PU) foams as microbial carriers. In general, the specific surface area of PU foams increases with respect to decreasing pore sizes. However, the number of microbes adhered on the unit surface of reticulated PU foams decreases with respect to decreasing pore sizes. Thus, as a result of totally considering all effects such as apparent density, hydrolysis rate, and adhesion, we can know that PU foams with 45 PPI is the most appropriate microbial carrier. In this study, we can also investigate the effect of various physico-chemical surface treatments on the adhesion of microbes on the surface of PU foams. We used a chitosan treatment, a PEI (Polyethylene Imine) treatment, a xanthane treatment and a plasma treatment. As a result of comparing all surface treatments, the plasma surface treatment was the best.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.373-373
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• 2006

Rigid polyurethane foams(PUFs) are widely used in most areas of insulations such as storage tank and pipe line for transporting liquefied gas. Glass fiber and nanoclay are used for improvement in mechanical property and thermal insulation of rigid PUF at very low temperature(<$-150^{\circ}C$). These rigid PUFs have been characterized in terms of thermal, mechanical, dynamic mechanical properties and cell morphology. It was found that mechanical properties, thermal conductivity and dimensional stability of rigid PU foams were improved by glass fiber and nanoclay.

• Elastomers and Composites
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• v.50 no.2
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• pp.81-86
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• 2015

In this study, natural rubber latex foam was prepared in order to replace commercialized polyurethane foams as a car seat material. Physical properties of the latex foam were investigated and the light stability was improved. The latex foam was mixed in an aqueous solution state, and the degree of foaming and the accelerator ratios were appropriately controlled. Tensile properties, hysteresis and dynamic mechanical properties of the latex foam were measured to compare with those of polyurethane foams. UV light absorbers and radical scavengers were added for improving light stability of the latex foam. Xenon lamp test was conducted to investigate the effects of the reagents on light stability. Our results revealed that the prepared latex foam including a light absorber with an antioxidant showed excellent light stable performances.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.5
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• pp.209-214
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• 2016

Foam reaction injection molding (FRIM) is a widely used process for manufacturing polyurethane foam with complex shapes. Numerical model for polyurethane foam forming reaction during FRIM process has been intensively investigated by a number of researchers to precisely predict final shapes of polyurethane foams. In this study, we have identified a problem related with a previous theoretical model for polyurethane foam forming reaction. Thus, previous theoretical model was modified based on experimental and computational results.

• Elastomers and Composites
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• v.40 no.4
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• pp.242-248
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• 2005

To study the fatigue properties of three type of foams for footwear midsole, polyurethane(PU), phylon(PH) and injection phylon(IP) foams were prepared with different hardnesses. Three types of foams were repetitively compressed for 50,000 cycles at 50 rpm. Cell shapes of foams were deformed with repetitive compression. The extent of cell deformation of IP was larger than those of PH and PU. Permanent strain of foam was made by repetitively compressing the foam, and the extent of IP was larger than those of PU and PH. Maximum compression forces of three types of the foams were decreased with the repetitive compression, and IP had the largest decrease in compression load of foam with compression. Decreases in maximum compression force of three types of foams were increased with increase of the hardness of foam.

• Elastomers and Composites
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• v.39 no.4
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• pp.274-280
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• 2004

Sorage modulus(G'), Impact and rebounding properties of polyurethane(PU), phylon(PH) and injection phylon(IP) foams were studied. The storage modulus of PU foam was dramatically increased with decreasing temperature. But the storage modulus(G') of IP and PH foams were not affected by temperature. The Impact force of PU foams was increased with decreasing temperature. But in the cases of IP and PH foams, the impact forces were not changed with temperature below $20^{\circ}C$. Impact farces of IP and PH foams were increased with the temperature above $20^{\circ}C$, but that of PU foam was not changed. Rebounding resilience of PU foam was lower than those of IP and PH foams from $-20^{\circ}C$ to $40^{\circ}C$.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2000.04a
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• pp.62-67
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• 2000

• Carbon letters
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• v.22
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• pp.60-69
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• 2017

Nitrogen-doped carbon nanosheets with a developed porous structure were prepared from polyurethane foams by hydrothermal carbonization following $ZnCl_2$ chemical activation. Scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, solid state $^{13}C$ nuclear magnetic resonance (NMR) spectra and X-ray photoelectron spectroscopy were used to characterize the nitrogen-doped carbon nanosheet structure and composition. The removal of Cr(VI) by the N-doped carbon nanosheets was investigated. The results showed that the maximum removal capacity for chromium of 188 mg/g was found at pH=2.0 with PHC-Z-3. pH had an important effect on Cr(VI) removal and the optimal pH was 2.0. Moreover, amino groups and carboxyl groups in the nitrogen-doped carbon nanosheet played important roles in Cr(VI) removal, and promoted the reduction of Cr(VI) to Cr(III).