• Elastomers and Composites
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• 제48권3호
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• pp.241-248
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• 2013

polyester형 polyurethane foam은 낮은 내가수분해성을 가지므로 quasi prepolymer법에 의한 acrylic polyol을 사용함으로써 극복될 수 있다. acrylic polyol을 함유한 polyurethane foam은 acrylic polyol 함량이 증가함에 따라 인장강도와 경도가 증가하였다. 하지만 split 인열강도와 인열강도는 약간씩 변화되었다. polyurethane foam의 내가수분해성은 인장강도의 손실 백분율로 측정하였으며 acrylic polyol 함량이 25.5g에서 102g으로 증가함에 따라 향상되었다.

• 접착 및 계면
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• 제3권2호
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• pp.1-8
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• 2002

물과의 발포반응에 의해 유츌유를 겔화할 수 있는 폴리우레탄 NCO prepolymer를 제조하기 위하여 폴리올(PTMG 및 GP)과 이소시아네이트(TDI)를 사용하여 NCO prepolymer를 합성하였다. 폴리올 각각의 분자량에 따라 합성한 NCO prepolymer를 이용하여 초기 유출유와 에멀젼된 유출유 그리고 유출유의 종류에 따라 유겔화율을 측정하였다. Bunker B 초기 유출유에 대하여 3관능성 폴리오인 GP1000의 경우 440%의 유겔화율은 나타내었으며, 유출유와 해수가 에멀젼(emulsion)된 상태에서는 2배 정도가 증가한 958%의 유겔화율을 나타내었다. 또한 Bunker B에 비해 점도가 높은 Bunker C의 에멀젼된 상태에서는 1098%의 유겔화율을 나타내었다. 사슬연장제가 투입된 2관능성 폴리올인 PTMG1000의 경우에는 에멀젼된 Bunker B에 대하여 910%의 유겔화율을 나타내었으며, 에멀젼된 Bunker C에 대하여 923%의 유겔화율을 나타내었다. 3관능성 폴리올을 사용하여 제조된 NCO prepolymer의 경우, 형성된 폴리우레탄 겔은 부드럽고 강한 특성을 가져 회수에 용이한 상태를 나타내었다.

• 한국염색가공학회지
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• 제27권3호
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• pp.184-193
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• 2015

In this study, dye encapsulated microcapsules were produced by polyurethane prepolymer synthesis method using hexamethylene diisocyanate, ethylene glycol and methyl ethyl ketone. The study showed that the average size of microcapsules were $4.697{\mu}m$ in normal distribution. These microcapsules were induced red color by thermochromic fluoran red dye with showing color change as temperature. After the textile finishing of microcapsules, durability of microcapsules were checked as crocking times and lightfastness. The microcapsules were pressed at protrusion of textile weave in 10 crocking times which meant that the microcapsules not fallen off. Lightfastness was acceptable giving rating 4. It means that the polyurethane microcapsules not affect to light durability.

• Elastomers and Composites
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• 제50권2호
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• pp.92-97
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• 2015

A study on reaction kinetics for a PTMG/TDI prepolymer with 2,2'-dichloro-4,4'-methylenedianiline (MOCA), of which formulations may be generally used for fabricating high performance polyurethane elastomers, was peformed using non-isothermal differential scanning calorimetry (DSC). A number of thermograms were obtained at several constant heating rates, and analysed using Flynn-Wall-Ozawa (FWO) isoconversional method for activation energy, $E_a$ and extended-Avrami equation for reaction order, n. Urea formation reaction of the present system was observed to occur through the simple exothermic reaction process in the temperature range of $100{\sim}130^{\circ}C$ for the heating rate of $3{\sim}7^{\circ}C/min$. and could be well-fitted with generalized sigmoid function. Though activation energy was nearly constant as $53.0{\pm}0.5kJ/mol$, it tended to increase a little at initial stage, but it decreases at later stage by the transformation into diffusion-controlled reaction due to the increased viscosity. Reaction order was evaluated as about 2.8, which was somewhat higher than the generally well-known $2^{nd}$ order values for the various urea reactions. Both the reaction order and reaction rate explicitly increased with temperature, which was considered as the indication of occurring the side reactions such as allophanate or biuret formation.

• 폴리머
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• 제29권2호
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• pp.156-160
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• 2005

Octamethylcyclotetrasiloxane$(D_4)$과 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane$(D_3^{Me,Ph)$을 1,1,3,3-tetramethyl-1,3-divinyldisiloxane(MVS)과 평형중합시켜 실리콘의 Si원자에 dimethyl 및 methylphenyl기가 도입된 $\alpha,\omega-vinyl$ poly(dimethyl-methylphenyl) siloxane prepolymer(VPMPS)를 제조하였으며, 또한 $D_4$와 1,3,5-trimethylcyclotrisiloxane$(D_3^:Me,H})$을 1,1,3,3-tetramethyldisiloxane(MS)와 평형중합시켜 Si원자에 dimethyl 및 methylhydrogen기가 도입된 $\alpha,\omega-hydrogen$ poly (dimethyl-methyl) siloxane prepolymer(HPDMS)를 제조하였다. Poly(acrylic acid)(PAA)을 chelating agent로 하여 nickel(II) nitrate와 iron(III) nitrate를 솔-젤 방법으로 PAA 금속염을 제조하고 이틀을 소결시켜 nickel ferrite 나노 입자를 제조하였다. 제조한 nickel ferrite는 XRD 패턴으로 확인하고 입자의 크기를 TEM으로 측정하였다 1,3-Divinyltetramethyldisilazane(VMS)으로 표면처리한 나노 실리카, nickel ferrite, VPMPS, HPDMS 및 촉매를 고속 교반기에 가하고 $130^{\circ}C$에서 컴파운딩하여 poly(organosiloxane) rubber nanocomposites를 제조하였다. Nickel ferrite 함유한 nanocomposite, POX-30과 POX-50을 각각 제조하였으며 이들의 기계적 및 열전도 특성 그리고 체적 저항을 측정하였다.

• 한국미생물·생명공학회지
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• 제15권2호
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• pp.122-128
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• 1987

Candida rugosa와 Rhizopus arrhizus 리파제를 photocrosslinkable resin prepolymer에 고정화시켜서 이소옥탄을 유기용매로 사용한 이상계를 이용해서 유지분해 및 에스테르교환 반응을 보고자했다. Dioctylsulfosuccinate가 가장 좋은 surfactant였다. 소수성 젤인 ENTP-3000에 고정된 리파제가 좋은 활성을 나타냈고 친수성 젤인 ENT-4000에 고정된 리파제가 유기용매에 대해 안정했다. 고정화 matrix의 소수성이 증가될수록Vm(app)는 증가되었으나 Km(app)는 거의 일정했다. 리파제의 최적 pH는 소수성 젤인 ENTP-3000에 고정된 경우 C. rugosa와 R. arrhizus 리파제에 대해서 각각 6.0과 6.5였으나, 친수성 젤에 고정된 리파제는 짧은 시간 반응에는 pH에 크게 영향을 받지 않았으나 긴 시간 동안 반응시킬 때는 역시 pH6.0과 6.5에서 각각 C. rugosa와 R. arrhizus 리파제가 높은 양의 지방산을 분해시켰다. 리파제를 entrapment 시키면 열안정성이 증가됨을 알 수 있었다.

• 한국전기전자재료학회논문지
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• 제23권11호
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• pp.891-895
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• 2010

Polymer dispersed liquid crystal (PDLC) films were prepared by the phase separation method using the liquid crystal (E7) and prepolymers. This work investigated the electro-optical characteristics of various PDLC films. In order to have good contrast ratio, the polymer refractive index must be adjusted to the ordinary refractive index of the liquid crystal. The driving voltage of PDLC films were mainly affected by elastic deformation. E7-Ebecryl810-IOA-TMPTA-HMPPO system had good threshold voltage and driving voltage and E7-Ebecryl810-EHA-PEGDA-HMPPO system had good contrast ratio.

• 한국기계가공학회지
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• 제13권2호
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• pp.81-88
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• 2014

Synthetic products such as casting tape and splints are rapidly replacing conventional plaster casts to treat orthopedic patients. Most synthetic products are produced through a polymerization process with related chemical agents. In this study, the effect of the process parameters on the residual NCO content within a prepolymer for casting tape and the hardening temperature for casting tape were experimentally evaluated. In order to verify the effects of the process parameters, an experimental method was adopted. From an S/N ratio analysis, optimal parameter combinations were determined to produce a pre-polymer with a suitable residual NCO content and alower hardening temperature. Prediction models for the NCO content and the hardening temperature were developed and confirmed.

• Elastomers and Composites
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• 제48권4호
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• pp.276-281
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• 2013

acrylic polyol로 개질한 polyester형 polyurethane foam을 quasi prepolymer법으로 제조하였다. 열적 및 동적 기계적 성질은 thermal gravimetric analysis 및 dynamic mechanical analysis에 의하여 분석하였다. 또한 유리전이온도는 differential scanning calorimeter로 측정하였다. Acrylic polyol 함량이 증가함에 따라 TGA에 의해 측정한 열적 안정성은 약간 감소하였다. 그리고 acrylic polyol 함량이 증가함에 따라 저장 탄성률은 증가한 반면에 tan delta 값은 감소하였다.

• 한국응용과학기술학회지
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• 제24권1호
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• pp.23-30
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• 2007

Kevlar was chemically surface modified with resorcinol-formaldehyde(RF) prepolymer and VP rubber latex for application to high strength tirecords. RF prepolymer was easily obtained by polymerization at room temperature in the presence of a base catalyst. The mechanical and thermal properties of Kevlar were not significantly changed during surface treated under various conditions. The change of adhesion with rubber were investigated through H-test method. Maximum increase of adhesion force between rubber and Kevlar was obtained up to 40% than that of untreated one when the fiber was soaked in RFL dipping solution and thermally treated at $170^{\circ}C$ for 3 - 5min.