• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.203-208
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• 2008

Recently, the modern society in development and industrial growth is investing a lot of time and much effort to improvement and environment of life quality. Thus, the casting tape which uses environmentally friendly and human body friendly water hardening process Polymer is rapidly substituted for the gypsum cast product which has been plentifully used in medical treatment. Until currently, prior researches have a tendency to focusing the analysis about chemical creation expense and reaction quality rather than the issue about optimization of the process for this polymerization. In the polymerization process which has been accomplished with actual same chemical creation expense, there has been a problem which is the possibility of getting a different result. This is because the optimization of respectively control factors is not accomplished which affect at polymerization process. Therefore, this research sees the chemical qualities of casting tape Polymer, consequently selects the polymerization process which is suitable. And, by using a experimental design, this research will evaluate the affects which the respective factors have on remaining NCO and viscosity. futhermore, this research will carry out the process optimization which can get the above results.

• 폴리머
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• 제32권5호
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• pp.433-439
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• 2008

고분자 소재에 평판형 플라즈마 전처리 방식을 적용시켜 polyurethane foam(density : 0.27)과 rubber (butadiene rubber) 소재 표면의 접촉각 및 접착력을 향상시켰다. 플라즈마 반응기의 최적의 반응조건을 조사하기 위해서 전처리기류(질소, 아르곤, 산소, 공기), 기류의 유량($30{\sim}100\;mL/min$), 그리고 전처리 시간($0{\sim}30\;s$) 등을 변화시켜 전처리하고 polyurethane foam의 경우 진공식 플라즈마처리 방식과 상호 비교하였다. 분위기 기류인 $N_2$의 유량을 100 mL/min로 설정 후 polyurethane foam은 10 s, rubber는 3 s 동안 전처리 했을 때 가장 높은 접착박리강도를 나타내었다. 전처리 후 소재의 표면 변화는 SEM과 ATR-FTIR을 이용하여 측정하였다. 결과적으로 평판형 플라즈마 조작 방식에 의한 처리로 소재 표면의 젖음성과 접착박리강도가 개선되었음을 확인하였다.

• Elastomers and Composites
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• 제55권1호
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• pp.13-19
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• 2020

4,4'-Methylenebis(2-chlorobenzenamine) (MOCA)-free fast curing polyurethanes were prepared. In this study, the processibility of a fast curing polyurethane system was characterized by assessing the pot life. The obtained pot life of the polyurethane was 6-8 s, indicating that this prepolymer-curative system is appropriate for ribbon flow casting. The influence of the NCO index on the viscosity and mechanical properties was evaluated. The viscosity, tensile strength, tear strength, and hardness of the as-prepared polyurethanes showed an increasing trend, with an increase in the NCO index, whereas the elongation at break increased initially and then decreased with an increase in the NCO index. The gel fraction and crosslink density showed a direct correlation with the NCO index, which substantiated the improved mechanical properties at the higher NCO index. The coefficients of friction and abrasion deteriorated with an increase in the NCO index.

• 한국염색가공학회지
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• 제31권3호
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• pp.165-176
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• 2019

Polyurethane-ureas(PUUs) were prepared from 4,4'-methylenebis(cyclohexyl isocyanate) and various diols including isosorbide. Isosorbide is starch-derived monomer that exhibit a wide range of glass transition temperature and are therefore able to be used in many applications. PUU was synthesized by a pre-polymer polymerization using a catalyst. Successful synthesis of the PUU was characterized by fourier transform-infrared spectroscopy. Thermal properties were determined by differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. It was found that by tuning isosorbide content in the resin, their glass transition temperature(Tg) slightly decreased. Physical properties were also determined by tensile strength and X-ray diffraction. There is no significant differences between petroleum-derived diol and isosorbide in XRD analysis. Moreover, their physical and optical properties were determined. The result showed that the poly(tetramethylene ether glycol)/isosorbide-based PUU exhibited enhanced tensile strength, transmittance, transparency and biodegradability compared to the existing diols. After 11 weeks composting, the biodegradability of blends increased in ISB-PUU. The morphology of the fractured surface of blend films were investigated by scanning electron microscopy.

• 한국기계가공학회지
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• 제18권2호
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• pp.1-6
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• 2019

With the increase in number of the athletic population and elderly demographic, the demand for orthopedic splints, which are used to support a damaged body, has rapidly increased. Current splints mainly consist of inner and outer parts, which are multiple fabrics covered with polyurethane and nonwoven fabrics, respectively. However, the laminated materials with directly applied pre-polymer coating lead to a high defect rate because of the uneven thickness on the surface. Thus, this study proposes an indirect coating method using a precise clearance controller, which enables the even application of the coating material on multiple inner parts while maintaining a constant thickness. In addition, a roll-to-roll (R2R) technique is applied instead of the sewing mechanism to bond the inner and outer materials together and enhance the productivity in the final stage. In the advanced methods, there is a storage tank that contains polyurethane, a clearance controller, and pairs of rollers in the upper and lower rows. To improve the quality of the products and optimize the equipment, three controllable factors are determined: the viscosity of polyurethane, angle of the gap controller and number of pairs of rollers in the R2R system.

• 한국막학회:학술대회논문집
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• 한국막학회 2003년도 The 4th Korea-Italy Workshop
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• pp.81-85
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• 2003

PU block polymers are constituted by sequences of constitutional units CU which are : a diisocyanate T, a polyol or a polyamine V, an extensor E .Due to the CU different solubility parameters ,hard and soft micro domains are formed;they can aggregate into different phases. A linear PU can be described by two parameters R=T/N and $R_{E}$=(R-1)V/E.A stoichiometric model is proposed which gives the general formula of all the possible PU: X((TV)$_{k}$(TE)$_{n}$)$_{m}$X , where k and m can be calculated from the experimental molecular weights respectively of pre polymer and polymer and n= R-1.Physical properties depend on PU composition and on nature of CU. I.R. analysis is useful for discovering the hydrogen bonds location : DSC gives informations on the presence of the different phases .PALS analysis shows that nano cavities become tighter on increasing n. A series of particular Pus ,obtained from :TDI, a low molecular weight polyol, a cyclic extensor, at different R and RE was prepared and analysed. These PU are amorphous, monophasic and appear to be good candidates for membranes.nes.nes.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.426-428
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• 2007

A simple method is presented for fabricating micro/nanoscale combined hierarchical structures using a two-step UV-assisted capillary molding technique. This lithographic method consists of two steps: (i) fabrication of partially cured polymer microstructures using a PDMS mold and (ii) subsequent nanofabrication using a high-resolution polyurethane acrylate (PUA) mold on top of the pre-formed microstructures. Using this technique, various micro/nano hierarchical structures were fabricated with minimum resolution down to 70 nm over a large area with very good reproducibility.

• 보존과학회지
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• 제26권3호
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• pp.335-340
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• 2010

유구 전사용으로 수입되어 사용되는 우레탄 수지 NS-10을 대체하기 위하여 1 차 유구 전사용과 토층 전사용 우레탄 수지를 합성하였다. 합성된 우레탄 수지는 NS-10과 비교하여 볼 때, 수분을 함유하는 토양에서 같은 침투력을 갖고 있으며, 유구 전사 시, 최종생성물인 에폭시 표면과 우레탄 pre-polymer 층의 박리에도 안정한 도막층을 형성하였다. 1 차 유구 전사용으로 사용될 우레탄은 NS-10과 같이 강한 인장 강도를 부여하고자 했으며, 토층 전사용 우레탄의 경우에는 역시 NS-10과 같은 인장 강도를 가지되 NS-10보다 경질성을 증가시켰다. 이 경질성의 증가로 인하여 토층 전사 후에도 토층 전사체 후면의 작업을 최소화할 수 있는 장점을 갖게 되었다. 최종적으로 합성된 우레탄 수지들을 실험실에서 제작한 압착 토양과 실제 유구와 유사한 토양에 직접 적용하여 본 결과, 기존에 사용하였던 NS-10과 비교하여 만족스런 침투력과 안정성을 가지고 있는 전사체를 형성함을 보여 작업자에게 편의성을 주는 우수한 전사용 수지였다.

• Korean Chemical Engineering Research
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• 제47권6호
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• pp.669-675
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• 2009

연질 PVC 대체를 위한 비변색 타입의 무용제형 상온 액상수지를 폴리올을 경화제로 사용하는 폴리우레탄수지 구조제어 설계를 통한 프리폴리머 합성방법을 응용하여 제조할 수 있었다. Macro-glycol, 분자량 및 반응조건의 영향 등을 고찰하여 최적의 작업성과 물성을 가지는 무용제형 상온액상수지를 제조하였으며, 우수한 기계적인 특성과 함께 유색작업을 위한 안료의 분산성 등에서도 우수하였고, Tg가 $-40^{\circ}C$의 값을 나타내었다. 또한 자외선 노출이나 질소산화물에 의한 황변특성도 개선할 수 있었다.

• 한국응용과학기술학회지
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• 제24권2호
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• pp.124-139
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• 2007

In order to obtain the maximum flame retardancy with the minimal deterioration of physical properties of PU flame-retardant coatings, chlorine and phosphorous functional groups were introduced into the pre-polymer of modified polyesters. In the first step, the tetramethylene bis(orthophosphate) (TBOP) and neohexanediol dichloroacetate (DCA-adduct) intermediates were synthesized. In the second step, 1,4-butanediol and adipic acid monomers were polymerized with the two kind of intermediates to obtain copolymer. The modified polyesters containing chlorine and phosphorous (ATBA-10C, -20C, and -30C) were synthesized by adjusting the contents of chlorine compound (dichloroacetic acid, 10, 20, 30 wt%) with fixed the content of phosphorous compound (2 wt%). The PU flame-retardant coatings (TTBAH -10C, -20C, and -30C) were prepared using the synthesized ATBAs and HDI-trimer as curing agent at room temperature. The physical properties of PU flame-retardant coatings with chlorine and phosphorous were inferior to those with phosphorous only and the properties were getting worse with increasing chlorine content. Flame retardancy was tested with three methods. With the vertical method, Complete combustion time of ATBAHs were $259^{\sim}347$ seconds, which means that the prepared coatings are good flame-retardant. With the $45^{\circ}$ Meckel burner method, char lengths of the three prepared coatings were less than 2.9 cm, which indicates that the prepared coatings are 1st grade flame retardancy. With the limiting oxygen index (LOI) method, the LOI values of the three prepared coatings were in the range of $30^{\sim}35%$, which proves good flame retardancy of the prepared coatings. From the results of flame retardancy tests of the specimens that contain the same amounts of flame retarding compounds, it was found that the coatings containing both phosphorous and chlorine show higher flame retardancy than the coatings containing phosphorous alone. This indicates that some synergy effect of flame retardancy exists between phosphorous and chlorine.