• 공업화학
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• 제21권5호
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• pp.500-504
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• 2010

다중벽 탄소 나노튜브(Carbon nanotube, MWNTs)의 우수한 전기적 기계적 특성과 폴리우레탄의 우수한 기계적 물성을 이용하여 우수한 전기 전도성 복합체를 제조하기 위하여 말단기가 polyurethane로 기능화 된 탄소 나노튜브(PU-g-MWNTs)를 제조하였다. 말단기에 형성된 폴리우레탄과 고분자 메트릭스 간의 상용성으로 인한 계면 접합력으로 인해 기능화된 CNT 복합체 기능화 되지 않은 CNT에 비해 우수한 분산성을 나타내었다. PU-g-MWNT/PU 복합체의 전기 전도성을 PU-g-MWNT의 농도에 따라 측정하였으며 percolation threshold 이론에 의해 해석하였다. 그 결과 PU-g-MWNT/PU 복합체의 전기전도성은 임계농도 0.78 wt%과 임계지수 0.945를 가짐을 확인하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.382.2-382.2
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• 2014

We explain a method to fabricate multi-layered transparent conductive films (TCF) using graphene oxide (GO), copper powder and polyurethane (PU) solution. The flexible graphene nanosheets (GNSs) serve as nanoscale connection between conductive copper nanoparticles (CuNps) and PU nanofibers, resulting in a highly flexible TCF. To fabricate conductive films with high transmittance, polyurethane (PU) nanofibers were used for a conductive network consisting of CuNps and GNSs (CuNps-GNSs). In this experiment, copper powder and graphene oxides were mixed in deionized water with the ultrasonication for 2 h. NaBH4 solution is used as a reduction agents of CuNps and GNSs (CuNps-GNSs) under a nitrogen atmosphere in the oil bath at 100% for 24 h to mixed. The purified and dispersed CuNp-GNS were obtained in deionized water, and diluted to a 10wt.% based on the contents of GNSs. Polyurethane (PU) nanofibers on a PET substrate were formed by electrospinning method. PET slides coated with the PU nanofibers were immersed into CuNp-GNS solution for several second, rinsed briefly in deionized water, and dried to obtain self-assembled CuNp-GNS/PU films. The morphology of the multi-layered films were characterized with a field emission scanning electron microscope (FE-SEM, Hitachi S-4700) and atomic force microscope (AFM, PSIA XE-100). The electrical property was analysed by the I-V measurement system and the optical property was measured by the UV/VIS spectroscopy.

• 패션비즈니스
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• 제23권2호
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• pp.1-17
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• 2019

The objective of this study was to investigate electrical conductivity of fabrics from polyester (PET) and Nylon (N) containing polyurethane (PU), with silver paste patterns screen-stenciled in three directions. The PET/PU and N/PU fabrics knitted or woven were uniaxially strain-recovered up to 22.5% in three times when each change in electrical resistance was simultaneously measured. This study established four variables that complexly affected electrical conductivity of these specimens; fabric structures, components, cover factors, and the percolation of silver particles. The woven or knitted fabric structures did not distinctively cause the changes in electrical resistance, however, the woven fabrics with the diagonal patterns showed their relatively high electrical resistance. The PET/PU fabrics with increasing the PET proportion generally presented the opposite propensity to its electrical conductivity. The changes in electric resistance of the PET/PU 85/15 2/1 twill and double plain fabrics instantaneously responded to the rate of elongation. The PET/PU group exhibited a reverse correlation between its cover factor and electrical resistivity. The highest electrical conductivity of the PET/PU 95/5 interlock fabric, with very few fluctuations, was attributed to the deep percolation of the silver particles that bridged the gaps between one loop and another. On the other hand, the occurrence of the silver cracks along with the elongated direction led to the immeasurably high change in electrical resistance as the strain increased.

• Journal of Microbiology and Biotechnology
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• 제13권1호
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• pp.70-76
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• 2003

The benzene removal characteritics of the polyurethane (PU) biofilter immobilized with S. maltophilia T3-c, that could efficiently degrade benzene, was investigated. Maximum capacity to eliminate benzene was maintained at $100-110g{\cdot}m^-3{\cdot}h^-1$ when space velocity (SV) ranged from 100 to $300 h^-1$ -1/, however, it decreased sharply to $55 g{\cdot}m^-3{\cdot}h^-1^$ as SV increased to $400 h^-1$. The critical elimination capacities that guaranteed $90\%$ removal of inlet loading of the PU biofilter were determined to be 70,30, and $15 g{\cdot}m^-3{\cdot}h^-1$ at SV 100,200, and $300 h^-1$, respectively. Based on the result of a kinetic analysis of the PU biofilter, maximum benzene elimination velocity ($V_m$) was $125 g{\cdot}m^-3^\;of\;PU{\cdot}h^-1$ and saturation constant ($K_m$) was $0.22 g{\cdot}m^-3^$ of benzene ($65{\mu}{\cdot}I^-1$). This study suggests that the biofilter utilizing S. maltophilia T3-c and polyurethane is a very promising technology for effectively degrading benzene.

• 한국염색가공학회지
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• 제23권2호
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• pp.118-130
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• 2011

In this study, hydrophilic polyurethane (PU) was synthesized by one shot process to get good non-swelling effect and to keep high breathability using reactive silicone oil of mono terminal and bi-terminal types. We also blended non reactive silicone oil with pure hydrophilic PU to compare non-swelling effect and breathability with hydrophilic PU synthesized by the two types of reactive silicone oils. The hydrophilic films were analyzed by nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscope (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photo electron (XPS) spectroscopy, energy dispersive spectrometry (EDS), breathability, waterproofness, tensile strength, contact angle and swelling effect. The results showed that the film made by hydrophilic PU which was synthesized with mono terminal type silicone oil provided good non-swelling effect and acceptable moisture permeability due to the modified surface properties.

• 한국염색가공학회지
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• 제18권4호
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• pp.28-36
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• 2006

The polyurethane prepolymers, which were previously synthesized from 2,4-toluene disocyanate(2,4-TDI) and polypropylene glycol(PPG), were chain extended by ethylene diamine or hydroxyl terminated polydimethylsiloxane(HTPMS) having hydroxy group at both ends of the chain, giving polyurethaneurea(PU) and polyurethane containing HTPMS segment(SiPU), respectively. In thermal gravimetric analysis, PU was almost completely degraded at $500^{circ}$ but SiPU showed about 11% residue at the same temperature. Suspension of SiPU and pigment showed more good compatibility than that of PU and pigment. The crocking fastness, migration fastness and solvent wicking were enhanced to 4.5 grades, 4 grades and 4 grades, respectively.

• 대한의용생체공학회:의공학회지
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• 제38권5호
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• pp.248-255
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• 2017

Polyurethane/polyethylene glycol(PU/PEG) hybrid scaffolds with various concentrations of PEG (0 to 50wt%) were prepared by electrospinning to evaluate the mechanical properties and the biocompatibility of the PU/PEG blend scaffolds. The 12wt% PU/PEG polymers were studied due to the absence of beads. The ultimate tensile strength of 12wt% PU was $8.2{\pm}0.5MPa$. The strength increased to $9.2{\pm}0.7MPa$ when 10% PEG was added to PU. However, the dry and the wet strength of PU/PEG scaffolds began to decrease dramatically when the PEG content was more than 10wt%. No cytotoxicity was observed for all the PU/PEG scaffolds investigated, indicating that the PU/PEG hybrid scaffolds are clinically safe and effective to small-diameter vascular grafts. In addition, the L-929 cells attached and proliferated well on the PU/PEG hybrid scaffolds.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.55-58
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• 2004

Cell separation from peripheral blood was investigated using surface-modified polyurethane (PU) membranes with different functional groups. Both red blood cells and platelets could pass through unmodified PU and PU-SO$_3$H membranes, while the red blood cells preferentially passed through PU-N(C$_2$H$_{5}$ )$_2$ and PU-NHC$_2$H$_4$OH membranes. The permeation ratio of T and B cells was less than 25% for the surface-modified and unmodified PU membranes. CD34$^{+}$ cells have been recognized as various kinds of stem cells including hematopoietic and mesenchymal stem cells. The adhesiveness of CD34$^{+}$ cells on the PU membranes was found to be higher than that of red blood cells, platelets, T cells or B cells. Overall, the adhesiveness of blood cells on the PU membranes increased in the following order: red blood cells $\leq$ platelets ＜ T cells $\leq$ B cells ＜ CD34$^{+}$ cells. Treatment of PU-COOH membranes with a human albumin solution to detach adhered blood cells, allowed recovery of mainly CD34$^{+}$ cells in the permeate, while both red blood cells and platelets could be isolated in the permeate using unmodified PU membranes. The PU membranes showed different permeation and recovery ratios of specific cells depending on the functional groups attached to the membranes.mbranes.

• 한국결정성장학회지
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• 제28권1호
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• pp.1-8
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• 2018

The 23 wt% polyvinylidene fluoride (PVDF)/15 wt% polyurethane (PU) fibers were electrospun using the conjugated nozzle at a flow rate of 1.0 mL/h and an electric field of 1 kV/cm. The formation of ${\beta}$ crystal phase in the PVDF and the PVDF/PU fibers was confirmed by Fourier transform infrared spectroscopy. After electrospinning, the asspun fibers were immersed in a boiling water and then dried at $100^{\circ}C$ in a convection oven to make a crimp phenomenon. The crimps with a diameter of $2.0{\pm}0.08{\mu}m$ were observed for the PVDF/PU fibers after hydrothermal treatment without sacrificing the extent of ${\beta}$ crystal phase. All the PU, PVDF and PVDF/PU fibers exhibited average cell viability of more than 98 %. The cell proliferation results suggested that L-929 cells adhered well to the PU, PVDF and PVDF/PU fibers and proliferated continuously with increasing time, indicating that the PVDF/PU fibers are highly applicable to the biomedical applications.

• Macromolecular Research
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• 제14권3호
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• pp.331-337
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• 2006

In the present study we investigated the relationship between the morphology and mechanical properties of electrospun polysulfone (PSF)/polyurethane (PU) blend nonwovens, by using the electrospinning process to prepare three types of electrospun nonwovens: PSF, PU and PSF/PU blends. The viscosity, conductivity and surface tension of the polymer solutions, were measured by rheometer, electrical conductivity meter and tensiometer, respectively. The electrospun PSF/PU blend nonwovens were characterized by scanning electron microscopy (SEM) and with a universal testing machine. The SEM results revealed that the electrospun PSF nonwoven had a structure consisting of cross-bonding between fibers, whereas the electrospun PU nonwoven showed a typical, point-bonding structure. In the electrospun PSF/PU blend nonwovens, the exact nature of the point-bonding structure depended on the PU contents. The mechanical properties of the electrospun PSF/PU blend nonwoven were affected by the structure or the morphology. With increasing PU content, the mechanical behaviors, such as Young's modulus, yield stress, tensile strength and strain, of the electrospun PSF/PU blend nonwovens were by up to 80%.