• 폴리머
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• 제24권1호
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• pp.8-15
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• 2000

본 연구에서는 초임계 이산화탄소를 반응 연속상으로 하여 졸-에멀젼-겔 방법에 의한 신합성 공정을 통해 1-6 $\mu\textrm{m}$의 평균 입자 크기를 갖는 페놀릭/퍼퍼랄(phenolic/furfural, P/F) 겔 입자를 성공적으로 제조하였다. 이때 초임계 이산화탄소에 잘 녹는 폴리디메틸실록산(poly-(dimethylsiloxane), PDMS)은 초임계 이산화탄소내에서 P/F 용액을 분산시키는 효과적인 안정제로 사용되었다. 입자 크기와 입자 크기 분포에 미치는 영향을 알아보기 위하여 고형분과 안정제 함량비를 변화시켜 실험한 결과, P/F 입자의 평균 입자 크기는 고형분의 함량비가 증가함에 따라 증가했으나, 안정제의 함량비에 따른 변화는 크지 않았다. 또한 P/F 겔 입자의 구조 및 열 안정성은 IR 분석과 TGA를 통해 확인하였다.

• 폴리머
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• 제32권3호
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• pp.219-229
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• 2008

A pH sensitive ternary copolymer gel was synthesized in the presence of ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent through radical polymerization of vinyl acetate (VA), acrylic acid (AA) and methyl acrylate(MA) with a weight ratio of 1 : 1.3 : 1. A number of experiments were carried out to determine the swelling behavior of the gel under a variety of pH conditions of the swelling medium. As the pH of the swelling medium was changed from 1.0 to 8.0 at $37^{\circ}C$, the gel showed a shift in the pH-dependent swelling behavior from Fickian (n=0.3447) to non-Fickian (n=0.9125). The resulting swelling parameters were analyzed using graphical and statistical methods. The results showed that the swelling of the gel was controlled by the pH of the medium, i.e. $n=n_o{\exp}(S_{C}pH)$, where n is the diffusion exponent, $n_o(=28.9645{\times}10^{-2})$ is the pre-exponential factor and $S_C$(=0.1417) is pH sensitivity coefficient. The swelling behavior of the gel was also examined in aliphatic alcohols. The results showed that the rate of swelling increased with increasing number of carbon atoms in the alcoholic molecular chain.

• Journal of Pharmaceutical Investigation
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• 제33권1호
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• pp.21-28
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• 2003

Ketorolac tromethamine(KT) is a nonsteroidal agent with potent analgesic and moderate anti-inflammatory activity. The lipid-water partition coefficient of KT was evaluated and KT gel was formulated as a gel containing different pH, different concentrations of polymer (poloxamer 407, carbopol 941), propylene glycol, ethanol and various enhancers. The resulting KT gels were evaluated with respect to their viscosity, in vitro drug permeation rate through hairless mouse skin and stability. In n-octanol and chloroform, the lipid-water partition coefficient of KT was the highest at pH 4 phosphate buffer. The apparent viscosity of KT gel increased with an increase in gel pH, polymer and enhancer concentration. But the apparent viscosity of KT gel decreased with an increase in ethanol concentration. The permeation rate of KT through hairless mouse skin from gels different pH was maximum at pH 4 which is close to KT $pK_{a}$ 3.54. The permeation rate decreased with an increase in polymer, propylene glycol concentration. But the permeation rate increased with an increase in ethanol. The increase of drug concentration from 1 to 3% induced linear increase in permeation rate. The best enhancer was the combination of $Labrasol^{\circledR},\;Transcutol^{\circledR}$, oleic acid and l-menthol. In the accelerated stability test(25, 40 and $50{\circ}C$), pH 5 gel was most stable and pH 4 gel was most unstable for 90 days.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.625-629
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• 2011

A quantitative analysis of the decreasing rate of the monomer and increasing rate of the polymerization was made by monitoring radiation level increments using Raman spectroscopy within the therapeutic radiation range for a normoxic polymethacrylic acid gel dosimeter. The gel dosimeter was synthesized by stirring materials such as gelatin, distilled water, methacrylic acid, hydroquinone and tetrakis phosphonium chloride at $50^{\circ}C$, and the synthesized gel was contained in a 10- mm diameter and 32-mm high vial to conduct measurement. 24 hours after gel synthesis, it was irradiated from 0 Gy to 20 Gy by 2 Gy using a Co-60 radiotherapy unit. With use of the Cryo FE-SEM, structural changes in the 0 Gy and 10 Gy gel dosimeters were investigated. The Raman spectra were acquired using 532-nm laser as the excitation source. In accordance with fitting the changes in C-COOH stretching (801 $cm^{-1}$), C=C stretching (1639 $cm^{-1}$) and vinyl $CH_2$ stretching (3114 $cm^{-1}$) vibrational modes for monomer and $CH_2$ bending vibrational mode (1451 $cm^{-1}$) for polymer, sensitive parameter S for each mode was calculated. The values of S for monomer bands and polymer band were ranged in $6.0{\pm}2.6$ Gy and $7.2{\pm}2.3$ Gy, respectively, which shows a relatively good conformity of the decreasing rate of monomer and the increasing rate of polymerization within the range of error.

• 공업화학
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• 제5권3호
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• pp.443-450
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• 1994

Polyacrylic acid를 NaOH와 $NH_4OH$로 중화시켜 중화도가 다른 polyelectrolyte를 만든 후, 수용액 상에서 ethylene glycol diglycidyl ether(EGDE)로 가교시켜 안정한 상태의 젤을 얻었다. 안정한 젤이 얻어지는 가장 작은 polyelectrolyte의 농도인 $C_{gel}$은 polyelectrolyte의 extended from에도 불구하고 비슷한 분자량의 중성 고분자의 간과 비슷하였다. 전해질 고분자에 대한 scaling이론에 의하면 semi-dilute영역에서의 전해질 고분자용액은 분자량 의존성이 없어야 함에도 불구하고 gelation결과는 중성 고분자와 흡사한 분자량 의존성을 보이며 entanglement 농도인 $C^{**}$와 비교했을 때에도 $C_{gel}$은 훨씬 큰 값을 갖는다. 이는 고분자 전해질의 농도가 진해질수록 용액의 이온세기가 증가하여 extended from에서 coil form으로 변화되기 때문으로 보인다. 고분자 전해질의 중화도에 따른 gelation은 100% 중화된 시료의 $C_{gel}$값과 분자량 의존성에 있어 거의 비슷한 경향을 보이며 이는 고분자 전해질의 conformation변화가 이온세기에 상당히 민감함을 보여 준다. 고분자 전해질 수용액에 추가로 저분자량의 염을 가하면 고분자의 용액 속에서의 크기가 더욱 축소하여 더 큰 $C_{gel}$값을 보인다.

• 한국의류산업학회지
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• 제20권4호
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• pp.422-428
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• 2018

In this study, we developed honeycomb pads using foam and polymer gel and verified the impact protection performance of pads for the development of a fall protection pants for elderly women aged 65 and over who have a high risk of fracture due to falls. The results are as follows; In the first experiment, the impact protection performance was evaluated for four honeycomb pad samples (CR foam, EPDM foam, hardness 15 polymer gel, and hardness 30 polymer gel) manufactured to a thickness of 5 mm using a single material. When the force of about 10757N was applied to the specimens, all four pads reduced the impact force to 3100N or less. Polymer gels showed better protection than foam materials. In the second experiment, the thickness of the protective pad was set to 8 mm in order to improve the shock absorbing performance of the protective pad. As a result of evaluating the impact protection performance of the foam single pad and foam gel composite pad, the impact absorbing performance of the foam single pad was better. Finally, four kinds of protection pads were made by assigning the foam single pad and the foam gel composite pad to pants type and underwear type respectively. The pad thickness of the main protection area was set to 8 mm to enhance the protection, and gradually decreased to 5mm and 3mm toward the edge to improve the appearance and fit.

• Bulletin of the Korean Chemical Society
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• 제24권10호
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• pp.1485-1489
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• 2003

The gelation for di-(2-ethylhexyl) phthalate (DEHP)-plasticized poly(vinyl chloride) was studied by measuring time-resolved small-angle X-ray scattering (SAXS) and a flow of the solutions in test tube. It was found that for the gelation there were three regimes. At Regime I, the solution rapidly changed to a gel, and the SAXS intensity showed a peak and the peak intensity increased, keeping the peak angle constant. Applying the SAXS intensity to the kinetic analysis of the liquid-liquid phase separation, it was revealed that the spinodal decomposition proceeded to develop a periodic length of 29.9 nanometer in size, a hydrogen-bonding-type association in polymer rich phase followed, and then it induced fast gelation rate. At Regime II, the gelation slowly occurred and the SAXS intensity was not observed, suggesting that a homogeneous gel network was formed by a hydrogen-bonding. At regime III, the solution was a homogeneous sol.

• Journal of Radiation Protection and Research
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• 제36권3호
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• pp.107-118
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• 2011

Conventional (SRS) and fractionated (FSRS) stereotactic radiosurgery necessarily require stringent overall target point accuracy and precision. We determine three-dimensional intracranial target point deviations (TPDs) in a whole treatment procedure using magnetic resonance image (MRI)-based polymer-gel dosimetry, and suggest a technique for overall system tests. TPDs were measured using a custom-made head phantom and gel dosimetry. We calculated TPDs using a treatment planning system. Then, we compared TPDs using mid bi-plane and three-dimensional volume methods with spherical and elliptical targets to determine their inherent analysis errors; finally, we analyzed regional TPDs using the latter method. Average and maximum additive errors for ellipses were 0.62 and 0.69 mm, respectively. Total displacements were 0.92 ${\pm}$ 0.25 and 0.77 ${\pm}$ 0.15 mm for virtual SRS and FSRS, respectively. Average TPDtotal at peripheral regions was greater than that at central regions for both. Overall system accuracy was similar to that reported previously. Our technique could be used as an overall system accuracy test that considers the real radiation field shape.

• 대한환경공학회지
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• 제31권8호
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• pp.603-610
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• 2009

본 연구는 휘발성유기화합물질의 분해능력을 가진 yeast인 Candida tropicalis를 이용하여, 대표적인 휘발성 유기화합물질인 톨루엔과 MEK의 제거효율을 향상시키기 위하여 수행되었다. 반응기는 가스상으로 유입되는 톨루엔과 MEK의 물질전달 능력을 향상시키기 위하여 airlift loop 형태로 선택하였고, yeast 미생물의 효과적인 포괄고정화를 위해 분말활성탄(PAC)과 알지네이트(Alginate), PEG로 고분자 담체를 형성하였다. Airlift loop bioreactor의 물질전달성능을 평가하기 위한 실험을 수행하였으며, 기체체류시간 15초에서 담체를 첨가하지 않은 액상의 톨루엔 물질전달계수($K_La$) 값이 1.29 $min^{-1}$이었으나, 고분자 담체를 첨가한 경우 톨루엔의 $K_La$는 4.07 $min^{-1}$로 증가하였다. 따라서 고분자담체를 적용하는 것이 기상으로 유입되는 휘발성유기화합물의 물질전달을 향상시키는 것으로 확인되었다. 이러한 airlift loop bioreactor와 yeast 포괄고정 담체를 적용하여 체류시간을 60초, 30초, 15초에서 유입부하에 변화를 주며 실험을 진행한 결과, 톨루엔 5, 10, 19, 37 g/$m^3$/hr, MEK 4.5, 8.9, 17.8, 35.1 g/$m^3$/hr의 유입부하 변화에도 전체 80% 이상의 안정적인 처리효율을 나타내었다. 또한 airlift loop bioreactor의 분해능을 확인하기 위하여 유입부하를 단기간 변화시켜 주며 실험한 결과, 톨루엔과 MEK의 최대분해능은 각각 70.4 g/$m^3$/hr, 56.4 g/$m^3$/hr로 확인되었다.

• 화약ㆍ발파
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• 제36권4호
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• pp.35-47
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• 2018

본 연구에서는 콘크리트 블록발파 실험과 AUTODYN 수치해석을 통해 몇 가지 전색제 및 충전재가 폭발결과에 미치는 효과를 분석하였다. 전색제와 충전재는 공기, 모래, 폴리머 겔을 이용하였다. 이들 재료들의 전색효과 및 충전효과는 밀장전 조건의 경우와 비교하였다. 매립된 콘크리트 블록을 사용하여 현장 누두공 시험을 실시하였다. 콘크리트 블록 실험 및 수치해석 결과 폴리머 겔을 사용한 경우가 모래 및 디커플링의 경우에 비해 누두공의 크기와 발파공 주위의 최대압력이 더 크게 나타나는 것을 확인하였다. 또한, 수치해석 결과는 현장시험 결과와 잘 일치하는 경향을 보여주었다. 주변암반 중에서 계산된 최대압력은 폴리머 겔, 모래, 무전색 및 디커플링 조건일 때 각각 37, 30, 16 MPa로 나타났다. 수치해석 모델 내 밀장전 시 최대 압력은 52 MPa로 가장 높게 나타났다. 그러나 손상영역의 크기는 폴리머 겔을 사용한 경우보다 작게 나타났다. 또한, 밀장전은 기준 실험으로 사용되었다.