• Textile Coloration and Finishing
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• v.19 no.4
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• pp.26-31
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• 2007

Nanocomposite resin(PUD-CNT) composed of Carbon nanotube(CNT) and Polyurethane Dispersion (PUD) was prepared by different contents of CNT($0{\sim}5%$). PUD-CNT was coated on samples, and their electrical conductivity was investigated. With increasing CNT content, static change, half life and surface resistance decreased. Composites having 5% CNT showed $10^9{\Omega}/cm$(surface resistance), and 40V (stactic charge). Respectively, From this results, PUD-CNT can be used as a antistatic material.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1357-1359
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• 1994

In this study, in order to improve the problem that dielectric breakdown strength decrease remarkably at high temperature, simultaneous interpenetrating polymer networks method was Introduced so that epoxy insulating material could have stable temperature characteristics and stable dielectric breakdown characteristics at whole temperature range. So network structure of epoxy/$SiO_2$ composite material was changed by adding MA and MA/PU into epoxy resin. DC voltage is applied into the specimen fabricated by this method, and then the result was compared and investigated.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.194-197
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• 2004

In this paper, compressive characteristics of carbon fabric skin with polymeric foam core sandwich structure were investigated by FE analyses and compressive tests of polyurethane foam were also conducted with respect to temperature changes, which were determined by curing processes of epoxy or polyester resin to obtain mechanical behaviour of polyurethane foam. FE analyses indicated variation of parameters with respect to manufacturing pressure, which have comparatively massive effect upon mechanical properties of sandwich structures, i.e. wavelength as well as crimp angle of carbon fabric

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3177-3183
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• 2012

The carbon nanofibers (CNFs) used in this study were synthesized with an iron catalyst and ethylene as a carbon source. A concentration of 30 wt % iron(III) acetylacetonate was dissolved in resol type phenol resin and polyurethane foam was put into the solution. The sample was calendered after being cured at $80^{\circ}C$ in air for 24 h. Stabilization and carbonization of the resol type phenol resin and reduction of the $Fe^{3+}$ were completed in a high-temperature furnace by the following steps: 1) heating to $600^{\circ}C$ at a rate of $10^{\circ}C/min$ with a mixture of $H_2/N_2$ for 4 h to reduce the $Fe^{3+}$ to Fe; 2) heating to $1000^{\circ}C$ in $N_2$ at a rate $10^{\circ}C/min$ for 30 minutes for pyrolysis; 3) synthesizing CNFs in a mixture of 20.1% ethylene and $H_2/N_2$ at $700^{\circ}C$ for 2 h using a CVD process. Finally, the structural characterization of the CNFs was performed by scanning electron microscopy and a synthesis analysis was carried out using energy dispersive spectroscopy and X-ray photoelectron spectroscopy. Specific surface area analysis of the CNFs was also performed by $N_2$-sorption.

• Journal of the Korean Wood Science and Technology
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• v.30 no.2
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• pp.172-179
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• 2002

In this study, two materials treated with a flame retardant were examined for their fire resistance. The first, MDF (medium density fiberboard) was overlaid by an oak sliced veneer, which was either treated by soaking in a 6wt.% solution of flame retardant chemicals (pentabromine-chlorinated paraffin) or non-treated and then was coated with either a flame retardant polyurethane coating or with a common polyurethane coating. The second material, Pinus koraiensis penal was either treated by a spray treatment using a flame retardant solution or non-treated and then was coated with either a flame retardant polyurethane coating or with a common polyurethane coating. Pentabromine-chorinated paraffin chemicals were added (6 part of urethane resin) as the flame retardant chemicals in the polyurethane coatings. In the fire resistance test, the th𝜃(℃·min) decreased with the flame retardant treatment or/and the flame retardant coatings, compared to the untreated sample Weight loss (%) decreased with the flame retardant treatment or/and the flame retardant coatings. The ignition time (sec.) increased and the residual flame time (sec.) decreased with the flame retardant treatment or/and flame retardant coatings. Therefore, the flame retardant treatment or/and flame retardant polyurethane coatings have excellent incombustibility.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.134-152
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• 2020

Objectives: The objective of this study was to evaluate volatile organic compounds (VOCs) and toluene diisocyanates (TDIs) exposure among polyurethane waterproofing workers in the construction industry. Methods: Task-based personal air samplings were carried out at seven construction sites using organic vapor monitor for VOCs (n=88) and glass fiber filters coated with 1-(2-pyridyl)piperazine(1-2PP) for TDIs (n=81). The concentration of VOCs and TDIs were shown for four different work types(mixing paint, primer roller painting, urethane resin spread painting, painter assistant) at five different worksites (rooftop, ground parking lot, piloti, bathroom, and swimming pool). The two TDI sampling methods (filter vs impinger) were evaluated in parallel to compare the concentrations. Results: The geometric mean(GM) concentration of VOCs Exposure Index (EI) was highest for primer roller painting (1.4), followed in order by, urethane resin spread painting (0.85), mixing paint (0.53), and painter assistant (0.35) by work types. The GM of VOCs EI was highest for bathroom (1.4) followed in order by, swimming pool (0.85), piloti (0.89), ground parking lot (0.82) and rooftop (0.57) by worksites. The GM of 2,4-/2,6-TDI concentration was 0.052 ppb and 0.432 ppb each. There was no statistical difference in TDIs concentrations among worksites. The concentration of 2,6-TDI was ten times higher than that of 2,4-TDI. The concentration of 2,6-TDI by impinger method was 5.7 times higher than that by filter method. Conclusions: In this study, we found 38.6% of the VOCs samples exceeded the occupational exposure limits and 19.8% of the 2,6-TDI samples exceeded 1 ppb among polyurethane waterproofing workers. The most important determinants that increase the concentration of VOCs and TDIs was indoor environment and primer painting work.

• Elastomers and Composites
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• v.39 no.1
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• pp.42-50
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• 2004

In this work, the diglycidylether of bisphenol A (DGEBA) and modified polyurethane (PU) blends were initiated by N-benzylpyrazinium hexafluoroantimonate (BPH). The cure and fracture toughness of neat DGEBA with the addition of PU were investigated. The cure properties of DGEBA/PU blend system were examined by DSC and near-IR measurements. The fracture touhtness were investigated by measuring the critical stress intensity factor ($K_{IC}$) and the critical strain energy release rate ($G_{IC}$). According to the results, the maximum values of owe activation energy ($E_a$) and conversion (${\alpha}$) were found at 10 phr of PU. Also the $K_{IC}$ showed a similar behavior with the results of conversion. These results were probably due to increase of crosslinking density in the blends resulted from increase of the hydrogen bonding between the hydroxyl groups of DGEBA and isocyanate groups of PU.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.283-284
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• 2003

습식응고법에 의한 다공성 폴리우레탄-부직포 합성피혁은 일반적으로 DMF 또는 MEK 둥의 용제로 희석한 폴리우레탄 수지에 니들펀칭 부직포를 함침하여 기포를 준비한 후, 폴리우레탄으로 코팅하여 비용매인 물에서 응고하는 방법으로 제조한다. 따라서 합성피혁은 부직포의 물성, 함침조건, 코팅조건 및 응고조건에 따라 물성의 차이를 나타낼 것으로 판단된다[l]. 특히 합성피혁의 물성은 폴리우레탄 코팅층의 내부에 형성되는 셀(cell)의 크기, 분포 및 형태에 크게 의존한다. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.285-286
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• 2003

폴리우레탄은 복합재료의 함침 및 코팅용으로 가장 보편적으로 사용되는 수지이다. 폴리우레탄-부직포 복합소재는 폴리에스테르 또는 나일론과 같은 합성섬유로 제조된 부직포에 폴리우레탄으로 함침한 후 다시 폴리우레탄으로 코팅함으로써 소재의 단위 무게 당 폴리우레탄이 차지하는 비율이 매우 높고, 최종제품의 물성에 많은 영향을 끼치므로 이와 관련한 연구는 주로 기능성 및 내구성을 부여하는데 맞춰지고 있다[1]. (중략)

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.24.2-24.2
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• 2010

고분자 몰드를 이용한 nanoimprint lithography (NIL)는 고분자소재의 유연성과 투명성으로 인하여, 유기전자소자나 유연한 디스플레이소자 등 다양한 응용이 가능하다. 하지만, 고분자소재는 일반적으로 열저항성과 내구성이 낮아서, 고분자 몰드를 이용한 패턴형성 시, 자외선 경화방식이 주로 사용된다. 만약 복제가 쉽고, 가격이 저렴하며, 열저항성과 내구성이 강한 고분자 몰드를 제작한다면, thermoplastic-NIL 기술에 적용할 수가 있기 때문에, 고온을 요구하는 소자의 패턴형성 공정에 사용 가능하다. 본 연구에서는 이러한 고분자 몰드 제작을 위하여, 열저항성과 내구성이 강한 polyimide 필름과 polyurethane acrylate (PUA)를 기반으로 제작된 resin을 이용하였다. 먼저 Polyimide 필름 위에 자외선 노광을 사용하여, PUA resin 을 경화시킴으로써 패턴을 형성하였다. 이렇게 만들어진 몰드를 thermoplastic-NIL기술에 적용함으로써, Si 기판 위에 sub-마이크로 급 패턴을 형성하였다. 또한, 제작된 고분자 몰드를 사용하여 반복적인 NIL 공정을 수행함으로써 몰드의 내구성을 확인하였으며, 곡면 기판 위에 NIL을 함으로써 몰드의 유연성을 확인 할 수 있었다.