• Archives of Plastic Surgery
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• v.35 no.6
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• pp.716-722
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• 2008

Purpose: Split or full thickness skin graft is generally used to reconstruct the palmar skin and soft tissue defect after release of burn scar flexion contracture of hand. As a way to overcome and improve aesthetic and functional problems, the authors used the preserved superficial fat skin(PSFS) composite graft for correction of burn scar contracture of hand. Methods: From December of 2001 to July of 2007, thirty patients with burn scar contracture of hand were corrected. The palmar skin and soft tissue defect after release of burn scar contracture was reconstructed with the PSFS composite graft harvested from medial foot or below lateral and medial malleolus, with a preserved superficial fat layer. To promote take of the PSFS composite graft, a foam and polyurethane film dressing was used to maintain the moisture environment and Kirschner wire was inserted for immobilization. Before and after the surgery, a range of motion was measured by graduator. Using a chromameter, skin color difference between the PSFS composite graft and surrounding normal skin was measured and compared with full thickness skin graft from groin. Results: In all cases, the PSFS composite graft was well taken without necrosis, although the graft was as big as $330mm^2$(mean $150mm^2$). Contracture of hand was completely corrected without recurrence. The PSFS composite graft showed more correlations and harmonies with surrounding normal skin and less pigmentation than full thickness skin graft. Donor site scar was also obscure. Conclusion: The PSFS composite graft should be considered as a useful option for correction of burn scar flexion contracture of hand.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.131-134
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• 2004

The object of this study is to design the Radar Absorbing Structures (RAS) having sandwich structures in the X-band $(8.2\~12.4GHz)$ frequencies. Glass fabric/epoxy composites containing conductive carbon blacks and carbon fabric/epoxy composites were used for the face sheets. Polyurethane (PU) foams containing multi­walled carbon nanotube (MWNT) were used for the core. Their permittivities in the X-band were measured using the transmission line technique. The reflection loss characteristics for multi-layered sandwich structures were calculated using the theory of transmission and reflection in a multi-layered medium. Three kinds of specimens were fabricated and their reflection losses in the X-band were measured using the free space technique. Experimental results were in good agreements with simulated ones in 10dB absorbing bandwidth.

• Science of Emotion and Sensibility
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• v.19 no.3
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• pp.43-50
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• 2016

The uniform nanofibers of polyurethane with different contents of Juniperus Chinensis extracts were successfully prepared by electrospinning method. Polyurethane is widely used as functional polymers in the industrials, medical field as their properties can be tailor-made by adjusting their compositions. Juniperus Chinensis has been reported for anti-tumor, anti-bacterial, anti-fungal, and anti-viral activities. PU/Juniperus Chinensis extracts composite nanofibers were produced at different Juniperus Chinensis extracts concentrations (0.25, 0.5, 1, 1.5wt.%). The effects of the major parameters in electrospinning process such as tip to collector distance (TCD), voltage, polymer concentration on the average diameter of electrospun nanoweb were investigated. As results, 12wt% PU solution concentration, 8kV applied voltage and 15cm tip to collector distance were identified as optimum conditions for electrospinning the composite nanofibers. The diameter and morphology of the nanocomposite nanofibers were confirmed by a scanning electron microscopy (SEM). The resulting fibers exhibited a uniform diameter ranging from 435nm~547nm. It has been found that the average diameters of fibers decreased by the adding of Juniperus Chinensis extracts. These nanowebs can be used for medical materials, protective clothing, and antimicrobial filters.

• Polymer(Korea)
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• v.31 no.4
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• pp.308-314
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• 2007

A composite film of polyurethane(PU)-graft-poly(acrylic acid) (PAAc)/polyaniline (PU-g-AAc/PANI) was successfully fabricated for the purpose of adding conductivity on the surface of a general purpose polymer and improving adhesive property between the general purpose polymer and conducting polymer layer. The results from ATR-FTIR and XPS analyses also supported the successful synthesis of the composite film by showing characteristic peaks for every step. A low surface resistivity of $2{\times}10^3\;ohm/sq$ proved the surface conductivity of synthesized PU-g-AAc/PANI film and the surface resistance decreased with increasing the amount of grafted AAc, which acted as a dopant for PANI film.

• Composites Research
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• v.33 no.1
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• pp.1-6
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• 2020

Dispersion and electrical resistance (ER) properties of polyurethane (PU) type topcoat were evaluated using carbon nanotube (CNT) with different CNT weight fraction. CNT was dispersed in PU type topcoat using ultra sonication dispersion method. CNT/PU topcoat was coated on carbon fiber reinforced epoxy composite (CFRC) surface using gravity feed spraying method. Static contact angles of CFRC and CNT/PU topcoat were performed using 4 types of solvents to calculate the work of adhesion between CNT/PU topcoat and CFRC surface. Surface resistance of CNT added PU topcoat was measured to determine CNT dispersion. Adhesion property between CNT/PU topcoat and CFRC was determined via cross hatch cutting test based on ASTM D3359. The optimized condition of CNT weight fraction was found.

• Polymer(Korea)
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• v.36 no.5
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• pp.643-650
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• 2012

In order to improve the thermal stability of polyurethane, we synthesized poly(adipate urethane) (PAU) and three PAU composites, PAU/30B (2.7 wt% 30B), PAU/MP (2.2 wt% MP), PAU/30B/MP (2.2 wt% 30B and 2.2 wt% MP), from poly(oxydiethylene adipate)-diol (PAD), 4,4'-methylene diphenyl diisocyanate (MDI), Cloisite 30B (30B), and melamine phosphate (MP). 30B and MP were introduced into the reactant mixture at the initial stage of the esterification between adipic acid and diethylene glycol, so 30B and MP were evenly dispersed in the PAU composites for long period. At temperatures lower than $250^{\circ}C$, the PAU composites were degraded faster than pristine PAU, mainly due to the decomposition of 30B and MP. At higher temperatures, the 30B and MP enhanced the thermal stability of the PAU composites. Compared with the pristine PAU, the thermal decomposition rates of the PAU composites decreased by 13~17%. In air, the residual weights of PAU/30B, PAU/MP, and PAU/30B/MP were 2.4, 2.3, and 7.3 wt% at $700^{\circ}C$, respectively.

• Composites Research
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• v.24 no.6
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• pp.7-11
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• 2011

Polyurethane oligomers (PUOs) such as UA8297, UP127 and EB8200 were utilized to enhance the anti-bullet property of Dyneema$^{(R)}$/vinylester composites. First, prepregs of PUO and vinylester (XSR10) were prepared via spray coating on Dyneema$^{(R)}$ fabric at 21 % resin content (by volume). In addition, spray coating and film lamination were also carried out with a mixture of XSR10/PUO for selected PUOs. Next, the prepregs were dried at RT for 1-2 h and then at $100^{\circ}C$ for 30 min to remove the solvent and to provide partial cure when necessary. The prepregs were stacked in 24 layers and cured at $120^{\circ}C$ for 5 min under the contact pressure and for additional 25 min at 150 $kg/cm^2$. Finally, the anti-bullet properties of composite samples were evaluated by measuring $V_{50}$ with simulated fragment projectile (SFP, 17 gr). The results showed a 6.5 and 9.0 % increase of $V_{50}$ with UP127 and EB8200, respectively.

• Journal of Korean Society on Water Environment
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• v.23 no.2
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• pp.281-286
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• 2007

A chemical and biological permeable barrier with economic feasibility is suggested to treat landfill leachate in this study. The proposed composite layers consist of bentonite, and polyurethane (PU) foam that is mixed with powdered activated carbon (PAC) and inoculated with microorganisms from local wastewater treatment plant. Each layer is mixed with local sand, and yellow brown soil. Batch tests were conducted to investigate the sorptions of nitrate on the PU foam and PAC, and nitrification/denitrification rate of each layer material. Nitrification occurred in 30 minutes with initial ammonia concentration of 100 mg/L, and the concentration of nitrate attached in the PU foam increased after 270 minutes. Results of denitrification batch tests showed 76.6%, 87.3% and 88% of nitrate removal efficiency at 10%, 20% and 30% of the volume ratio of PU foam, respectively. The pH increased from 7 to 9.42, and alkalinity increased from 980 mg/L to 1720 mg/L during the denitrification batch tests. In the column experiments using the proposed composite layers with 20% of the volume ratio of the PU foam, about 96% of BOD, 63% of COD, 58.1~79.5% of total nitrogen were removed.

• The Korean Fashion and Textile Research Journal
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• v.20 no.3
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• pp.353-359
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• 2018

In this study, fused deposition modellig(FDM) 3D printing technology has been applied directly to polyester voil fabric to produce 3D printed lace/voil composite fabrics. A stereolithograpy(STL) file with a lace type 3D modelling under the various thickness were prepared and transformed into a g-code file using a g-code generator. The extrusion conditions for FDM 3D printing were controlled by 50mm/s of nozzle speed, $235^{\circ}C$ of nozzle temperature, $40^{\circ}C$ of heating bed temperature. 3D printed lace/voil composite fabriscs manufactured by 3D printing based on FDM using a thermoplactic polyurethane(TPU) filaments were obtained. To evaluate the mechanical properties and washability of the fabricated 3D printed lace/voil composite fabric, KES-FB system test, washing fastness test and dry cleaning resistance test were conducted. As 3D printing thickness increased, KOSHI, NUMERI, and FUKURAMI of 3D printed lace/voil composite fabric increased. From the results of the primary hand value test, 3D printed lace/voil composite fabrics were confirmed to be applicable to women's summer garments. As a result of the washability and dry cleaning resistance test of the 3D printed lace/voil composite fabrics, all samples were graded 4-5.

• Journal of Fashion Business
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• v.23 no.2
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• pp.77-88
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• 2019

One way of appling 3D printing to garments is through the combination of 3D polymer filaments in textile fabrics. it is essential to understand the interface between the polymer and the 3D composite fabric in order to enhance the adhesion strength between the polymers and the peeling strength between the fabric and the polymer. In this study, the adhesion of composite printed specimens using a combination of fabric and polymers for 3D printing was investigated, and also the change in adhesion was investigated after the composite fabric printed with polymers was subjected to constant pressure. Through this process, the aims to help develop and utilize 3D printing textures by providing basic data to enhance durability of 3D printing composite fabrics. The measure of the peeling strength of the composite fabric prepared by printing on a fabric using PLA, TPU, Nylon polymer was obtained as follows; TPU polymer for 3D printing showed significantly higher peel strength than polymers of composite fabric using PLA and Nylon polymer. In the case of TPU polymer, the adhesive was crosslinked because of the reaction between polyurethane and water on the surface of the fabric, thus increasing the adhesion. It could be observed that the adhesion between the polymer and the fiber is determined more by the mechanical effect rather than by its chemical composition. To achieve efficient bonding of the fibers, it is possible to modify the fiber surface mechanically and chemically, and consider the deposition process in terms of temperature, pressure and build density.