• 한국막학회:학술대회논문집
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• 한국막학회 2005년도 춘계 총회 및 학술발표회
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• pp.95-99
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• 2005

• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 추계 총회 및 학술발표회
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• pp.37-38
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• 1998

물질을 분리하기 위해서는 두 물질간의 현저한 물리적 성질의 차가 있어야 한다. 일반적으로 막분리법을 이용하여 기체분리를 수행하느 경우에는 확산계수와 용해도 차이에 의한 투과선택도를 얻게 된다. 막분리를 위한 기체간의 물리적 성질로는 기체의 크기차이, 고분자에 대한 기체용해도 차이 등이 있다.(생략)

• 폴리머
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• 제24권2호
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• pp.281-286
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• 2000

분자량이 각각 500, 1000, 2500인 비정형 polyether와 sebacoyl chloride로부터 분자량이 약 8000~15000정도인 지방족 폴리에스테르 공중합체를 합성하였으며, $^1$H-NMR과 FT-IR을 이용하여 구조와 조성을 분석, 확인하였다. 합성된 폴리에스테르의 경우, 3가지 시료 모두 결정은 관찰되지 않았으며 사용된 polyether의 분자량에 관계없이 유리전이온도가 약 -77$^{\circ}C$인 완전한 비정형 물질을 얻을 수 있었다. 반면에 poly(ethylene glyool) (PEG)을 이용한 경우는 사용한 PEG의 분자량이 증가함에 따라 공중합체의 융점과 결정화도가 증가함을 알 수 있었다. 분자량이 200과 400인 PEG를 이용한 경우에는 약 -71$^{\circ}C$ 정도의 유리전이온도를 보였으며, 융점은 -42.4$^{\circ}C$와 -22.4$^{\circ}C$에서 관찰되었다. 그러나 분자량이 1000인 PEG를 이용한 경우에는 융점이 23.$0^{\circ}C$로 나타났다. 또한 사용된 PEG의 분자량이 증가할수록 공중합체의 결정화도는 8.8%, 16.2%와 46.7%로 증가하였다.

• 대한치과보철학회지
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• 제34권4호
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• pp.850-868
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• 1996

The accuracy and dimensional stability of impression materials are one of the most important factors for successful prosthodontic treatment. The purpose of this study was to evaluate the accuracy of several dental elastomeric impression materials used widely and clinically : Impregum-$F^{(R)},\;Permlastic^{(R)},\;Silascon^{(R)},\;Perfect^{(R)},\;Xantopren^{(R)}$. There have been many studies to evaluate the accuracy of impression materials. But it has not been decided yet, which method was most suitable for the evaluation of the accuracy. In this study, two resin teeth, #15 & 25, were prepared with rounded shoulder margin and 90 degree cavosurface angle. For the polysulfide rubber and polyether, the custom tray was made at least 24 hours prior to impression taking. For the silicone rubber materials, putty/wash impression technique was applied in taking impressions. Marginal openings of the castings on the master dies and prepared resin teeth were measured under stereomicroscope. The results were statistically analyzed and compared between tested impression materials. The results were as follows ; 1. In the overall accuracy of impression materials, polyether was the most accurate one, followed by polysulfide, additional silicone and condensation silicone. 2. On the first model pouring, condensation silicone had the largest discrepancies and there was significant difference compared to the other impression materials. 3. Polysulfide had the least discrepancies in the first model pouring, but showed larger discrepancies in the immediate second pouring than the first pouring. 4. On the immediate second pouring, the discrepancy of polyether was shown to be the smallest, while the largest one was additional silicone. 5. Polyether and polysulfide rubber using custom impression trays showed superior accuracy to silicone rubber, putty/wash impression technique.

• 접착 및 계면
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• 제23권1호
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• pp.8-16
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• 2022

본 연구에서는 폴리올의 혼합으로 폴리우레탄의 물성 저하를 보완하고자 하였다. 신발 및 소재 코팅용으로서 자가치유 기능을 가지는 수분산 폴리우레탄 수지를 합성하기 위해 내구성 및 내열성이 우수한 polyether 폴리올과 기계적 물성이 뛰어난 polycarbonate 폴리올을 병용하여 합성하였으며, 자가치유 기능의 부여를 위해 disulfide기를 도입하였다. 합성된 자가치유 기능 수분산 폴리우레탄은 fourier transform-infrared spectroscopy (FT-IR)을 통해 확인되었으며, universial testing machine (UTM)과 scanning electron microscope (SEM) 측정을 통해 물리적 특성 및 자가치유 특성을 확인하였다. Polycarbonate 폴리올을 병용함으로써 인장강도 및 경도가 증가하였고, 신장율은 감소하였다. 또한 열적 특성의 비교 결과, polycarbonate 폴리올의 함량이 증가함에 따라 열 안정성이 증가하였다. 치료효율은 poly(tetramethylene ether)glycol : polycarbonate polyol = 0.75 : 0.25일 때 가장 높은 효율을 보여주었으며, 현미경 및 SEM을 이용한 표면 관찰을 통해 손상 부분이 치유된 것을 확인하였다.

• Fibers and Polymers
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• 제7권4호
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• pp.404-413
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• 2006

This study examines multiple quality optimization of the injection molding for Polyether Ether Ketone (PEEK). It also looks into the dimensional deviation and strength of screws that are reduced and improved for the molding quality, respectively. This study applies the Taguchi method to cut down on the number of experiments and combines grey relational analysis to determine the optimal processing parameters for multiple quality characteristics. The quality characteristics of this experiment are the screws' outer diameter, tensile strength and twisting strength. First, one should determine the processing parameters that may affect the injection molding with the $L_{18}(2^1{\times}3^7)$ orthogonal, including mold temperature, pre-plasticity amount, injection pressure, injection speed, screw speed, packing pressure, packing time and cooling time. Then, the grey relational analysis, whose response table and response graph indicate the optimum processing parameters for multiple quality characteristics, is applied to resolve this drawback. The Taguchi method only takes a single quality characteristic into consideration. Finally, a processing parameter prediction system is established by using the back-propagation neural network. The percentage errors all fall within 2%, between the predicted values and the target values. This reveals that the prediction system established in this study produces excellent results.

• 한국수소및신에너지학회논문집
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• 제28권1호
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• pp.17-23
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• 2017

Polyether ether ketone (PEEK) composite including tungstophosphoric acid(TPA) membranes have been intensively investigated for polymer electrolyte membrane water electrolysis (PEMWE) and thus covalently linked sulfonated polyether ether ketone (CL-SPEEK) with captured TPA composite membranes were prepared and characterized. Sulfonated polyether ether ketone (SPEEK) was prepared in sulfonation of PEEK and was cross-linked with 1,4 diiodobutane. The carbonyl group of SPEEK was reduced with $NaBH_4$ and 3-isocyanatepropyltriethoxysilane (ICPTES) was added. The TPA captured composite was prepared in reaction of TPA with 3-mercaptopropyltrime thoxysilane (MPTMS). The polymer composite membranes showed better thermostability and electrochemical properties than SPEEK. The membranes were prepared by sol-gel casting method. The polymer composite membrane featured 0.1285 S/cm of proton conductivity at $80^{\circ}C$ and outstanding durability.

• 한국수소및신에너지학회논문집
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• 제28권4호
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• pp.338-344
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• 2017

Polyoxometal molybdophosphoric acid (MoPA) bonded polyether ether ketone (PEEK) composite membrane for water electrolysis has been investigated. The composited membrane, covalently cross linked (CL) sulfonated polyether ether ketone (SPEEK) with a bonded MoPA, was prepared in sulfonation of PEEK, cross linkage reaction with 1,4-diiodobutane, and addition with MoPA. PEEK was covalently cross-linked with 1,4-diiodobutane to improve mechanical strength and was added with MoPA to increase proton conductivity. MoPA should be fixed to back bone of SPEEK to prevent bleeding out. Therefore, the carbonyl group of SPEEK was reduced with NaBH4 and 3-isocyanatepropyltriethoxysilane (ICPTES) was added. The MoPA bonded composite was produced in the reaction of MoPA with 3-mercaptopropyltrimethoxvsilane (MPTMS). In conclusion, MoPA bonded CL-SPEEK composite membrane featured 0.129 S/cm of proton conductivity at $80^{\circ}C$, and 2,156 hours of chemical stability in Fenton test. These properties are better than those of membranes of other SPEEK system.

• 대한치과보철학회지
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• 제30권2호
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• pp.233-245
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• 1992

The purpose of this study was to evaluate the demensioal stability and wettability of several rubber impression materials. Impressions were made from a metal master die machined to stimulate five full veneer crown preparations symmetrically placed in an arch form. Cast from impressions were measured about ; 1) intrapreparation distance 2) lower base diameter 3) length. For comparing materials were formed against a smooth surface. The advancing contact angle of a saturated aqueous solution of $CaSO_4$ on the impression materials was measured after 1 minute. Mean contact angle were calculated and results were analyzed. Results were as follows : 1. As the intrapreparation distance, hydrophilic addition-cured silicone had the smallest change and condensation-cured silicone had the largest one. 2. As the lower base diameter, traditional addition-cured silicone had the smallest change and polyether had the largest one. 3. As the height, traditional addition-cured silicone had the smallest change and polyether had the largest one. 4. As the contact angle, polyether had the smallest change and condensation-cured silicone had the largest one.

• 공업화학
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• 제10권4호
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• pp.615-619
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• 1999

스테아릴트리메틸암모늄 이온만 삽입된 몬모릴로나이트는 나노복합재료를 형성하지 못하였다. 그러나 스테아릴트리메틸암모늄과 m-페닐렌디암모늄 염이 함께 삽입된 몬모릴로나이트와 diglycidyl ether of bisphenol A(DGEBA)와 가열하면 중합반응이 일어나 폴리에테르-몬모릴로나이트의 나노복합재료를 합성하였다. 합성한 나노복합재료를 XRD과 TEM을 통하여 에폭시 메트릭스내의 몬모릴로나이트의 실리케이트층이 한층 균일하게 분산되어 있음을 확인하였다. 그리고 각각의 실리케이트 층간거리는 $250{\sim}500{\AA}$ 정도였다.