• 한국염색가공학회지
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• 제24권1호
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• pp.69-78
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• 2012

This paper surveys the physical properties of the MWNT dispersion solution dispersed with the three types of solvents and of the polyurethane composite film for improvement of mechanical properties and electrical characteristics of PU/MWNT composite film. For this purpose, the MWNT dispersed solution was mixed with three types of solvent such as IPA, MEK and Toluene and then mixed with polyurethane (100part) with variation of loading content (0, 10, 20, 30, 40, 50 part) of MWNT dispersed solution in the ultrasonic wave dispersion apparatus. And eighteen PU/MWNT composite films were prepared as specimens. The various physical properties of these PU/MWNT films were measured and discussed with the loading content of three types of MWNT dispersed solutions. The highest absorbancy among the three types of dispersed solutions was shown in the IPA/MWNT solution. But the absorbancy of PU/MWNT films was not same as the solution. The low electrical surface and volume resistivity of PU/MWNT film were shown at the condition of 20 and 10 parts loading of IPA/MWNT dispersed solution, respectively. The low triboelectricity of PU/MWNT film was shown at the condition of above 30part loading of IPA/MWNT dispersed solution. The breaking strength and strain of PU/MWNT film prepared with IPA/MWNT dispersed solution were decreased with increasing loading content of IPA/MWNT from 10 to 40 parts. The maximum breaking strength and breaking strain according to the dispersion solution were shown on the IPA/MWNT dispersed solution. The uniform dispersion of PU/MWNT film according to the loading content of MWNT solution was shown by surface image analysis on the films dispersed with IPA.

• 한국염색가공학회지
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• 제22권2호
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• pp.118-122
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• 2010

The interest in textile which has far-infrared ray emissive property has been increased in the field of biophysics and medicine. In this study, far-infrared ray emissive polyurethane nano-web was obtained using electrospinning of polyurethane(PU) solution mixed with ceramics powder and far-infrared ray emissive properties of nano-web were evaluated by measuring far-infrared ray emission power and emissivity(%). To investigate the influence of concentration of ceramics powder in PU solution and temperature for far-infrared ray emissive properties, far-infrared ray emissivity was measured at varied temperature using various nano-web including varied concentration of ceramics powder. Polyurethane nano-web was characterized by SEM to observe the deposition of ceramics powder on polyurethane nano-web surface. The far-infrared ray emissivity was increased with the concentration of ceramics powder in the nano-web. The far-infrared ray emission power was enhanced with increasing temperature of the samples; however, far-infrared ray emissivity was decreased with increasing temperature because the increase of emission power of ceramic containing nano-web was lower than the emission power of black body one.

• Elastomers and Composites
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• 제34권5호
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• pp.399-406
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• 1999

Polytetramethylene ether glycol (PTMG)와 4,4'-diphenylmethane diisocyanate (MDI), toluene 2,4-diisocyanate(TDI), isophoron diisocyanate(IPDI)로 polyurethane (PU) prepolymer를 합성하고, dimethylol propionic acid(DMPA)로 쇄연장시킨 후 triethyl amine(TEA)으로 중화시켜서 안정한 수분산성의 음이온성 폴리우레탄을 제조하였다. 음이온성 폴리우레탄의 합성과정에서 쇄연장제의 함량과 중화비에 따른 에멀젼의 유화안정성, 접착강도, 점도, 유리전이온도 및 cast film의 물리적 성질을 UTM, Viscometer와 DSC를 사용하여 검토하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.104-107
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• 2004

In this work, the blend of diglycidylether of bisphenol A (DGEBA) and modified polyurethane (PU) was prepared and characterized in the cure behaviors and mechanical interfacial properties. The N-benzylpyrazinium hexafluoroantimonate was used as a cationic initiator for cure, and the content of PU was varied within 0-20 phr. The cure behaviors and mechanical interfacial properties were studied by DSC, near­IR, and the critical stress intensity actor $(K_{IC})$ measurements. Also thermal stabilities were carried out by TMA and TGA analyses. As a result, the cure activation energy $(E_a)$ and the conversion $(\alpha)$ were slightly increased with increasing the PU content, and a maximum value was found at 10 phr PU. The mechanical interfacial properties measured from $K_{IC}$ showed a similar behaviors with the results of conversion. These results were probably due to the increase of the hydrogen bonding between the hydroxyl groups of DGEBA and isocyanate groups in PU.

• Transactions on Electrical and Electronic Materials
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• 제18권4호
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• pp.211-216
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• 2017

The dielectric properties of two polyurethanes (PUs) with different hard segments, i.e., aromatic methylene di-p-phenyl diisocyanate (MDI) and aliphatic hexamethylene diisocyanate (HDI), were investigated in the temperature range of -100 to $100^{\circ}C$ and in the frequency range of 1 Hz to 3 kHz. The ${\alpha}$-relaxations induced by the glass transition of the equivalent soft segments in the two PUs occurred at relaxation times of ${\tau}=3.46{\times}10^{-3}s$ for MDI-PU and ${\tau}=3.39{\times}10^{-2}s$ for HDI-PU at $-20^{\circ}C$, in accord with the temperature-frequency superposition principle, resulting in similar shifting factors. However, different I-relaxations were observed for the two PUs. The I-relaxation of MDI-PU occurred due to the mobility of the chain extenders near $80^{\circ}C$ with a slower shifting rate than the ${\alpha}$-relaxation. On the other hand, I-relaxation arising from both the extender and the unconstrained hard segments of HDI-PU occurred at $70{\sim}100^{\circ}C$, indicating complicated dielectric behavior due to partial interaction with the ${\alpha}$-relaxation at high frequencies. Thus, the I-relaxation of HDI-PU did not follow the superposition principle. The dielectric behaviors of the PUs were mainly influenced by their phase transitions, which were affected by the structure and components of the materials.

• 한국염색가공학회지
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• 제15권3호
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• pp.168-175
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• 2003

Ultramicrofiber(UMF) PET knitted fabric and regular PET plain woven fabric as reference sample were impregnated with waterborne polyurethane(PU) in a two-step process with dyeing/PU treatment and PU treatment/dyeing to investigate the effect of the treatment sequence. The waterborne PU impregnated fabrics were dyed with two kinds of vat and disperse dyes to investigate the dyeing properties and the dyeing fastnesses. In vat dyeing the rank of color strength(K/S) was in order of dyeing/PU impregnation > dyeing only > PU impregnation/dyeing, whereas in case of disperse dyeing, the order was dyeing/PU impregnation > PU impregnation/dyeing >dyeing only. Wash fastness of vat dyeing showed a higher 2-3 grade than disperse dyeing, while rubbing and light fastnesses were not good for disperse dyes.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2002년도 봄 학술발표회 논문집
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• pp.474-477
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• 2002

열가소성 폴리우레탄(PU)은 우수한 탄성을 갖는 유용한 고분자중의 하나로 섬유나 플라스틱에 널리 사용되고 있다. PU는 상온보다 높은 유리전이 온도(T$_{g}$)를 갖는 유리상의 hard segment와 상온보다 낮은 유리전이 온도(T$_{g}$)를 갖는 고무상의 soft segment로 구성되어 있으며 열역학적으론 비상용성으로 인하여 미세 상분리 구조를 가지게 되어 고무보다 높은 탄성률과 우수한 인장 회복거동을 갖게 된다[1-3]. (중략)

• Elastomers and Composites
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• 제35권4호
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• pp.281-287
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• 2000

폴리테트라메틸렌글리콜(PTMG) 및 디메틸올프로피온산(DMPA)의 몰비를 변화시키며 수분산성 폴리우레탄 마이크로겔 분산체를 합성하였다. 합성한 폴리우레탄 마이크로겔의 입도분포, 열적 및 기계적특성을 실험하였다. 마이크로겔의 입자크기는 $98{\sim}$680{\mu}m 범위에 분포되어 있으며, DMPA와 1,2,6-hexanetriol의 몰비가 증가함에 따라 감소하였다. 마이크로겔의 유리전이온도 및 융점은 각각 $-79.7 {\sim}-78.1^{\circ}C$, $22{\sim}24^{\circ}C$ 범위였으며, PTMG/DMPA의 몰비가 60/40인 폴리우레탄 마이크로겔 필름의 인장강도 및 신장률이 최대값을 나타내었다.

• 공업화학
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• 제31권5호
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• pp.487-494
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• 2020

기존의 방열필름의 연소문제를 해결하기 위해 poly(tetra methylene glycol) (PTMG), 4,4'-methylenebis(phenyl isocyanate) (MDI)와 유기인이 도입된 실란 커플링제로 표면개질한 질화붕소를 사용하여 폴리우레탄과 개질된 질화붕소로 이루어진 복합체를 제작하였다. Fourier transform-infrared (FT-IR) 분광 분석을 통해 질화붕소의 개질과 복합체의 합성 여부를 확인하였다. 또 universal testing machine (UTM) 측정을 통해 개질된 질화붕소의 함량에 따른 복합체의 기계적 물성 변화를 확인하였으며, layser flash analysis (LFA)와 UL94 측정을 통해 열적 특성을 조사하였다. 그 결과, 복합체의 열전도도가 1.19 W/m·K로 증가하였으며, 자기소화성이 없어 타기 쉬운 폴리우레탄의 난연성이 UL94 V-1 등급으로 향상되었다.

• Macromolecular Research
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• 제17권7호
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• pp.458-463
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• 2009

Polyurethane (PU) is widely used as a cardiovascular biomaterial due to its good mechanical properties and hemocompatibility, but it is not adhesive to endothelial cells (ECs). Cell adhesive peptides, GRGDS and YIGSR, were found to promote adhesion and spreading of ECs and showed a synergistic effect when both of them were used. In this study, a surface modification was designed to fabricate an EC-active PU surface capable of promoting endothelialization using the peptides and poly(ethylene glycol) (PEG) spacer, The modified PU surfaces were characterized in vitro. The density of the grafted PEG on the PU surface was measured by acid-base back titration to the terminal-free isocyanate groups. The successful immobilization of pep tides was confirmed by amino acid analysis, following hydrolysis, and contact angle measurement. The uniform distribution of peptides on the surface was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). To evaluate the EC adhesive property, cell viability test using human umbilical vein EC (HUVEC) was investigated in vitro and enhanced endothelialization was characterized by the introduction of cell adhesive peptides, GRGDS and YIGSR, and PEG spacer. Therefore, GRGDS and YIGSR co-immobilized PU surfaces can be applied to an EC-specific vascular graft with long-term patency by endothelialization.