• 대한화학회지
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• 제16권1호
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• pp.50-55
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• 1972

The mechanical degradation of $poly(\alpha-methyl$ styrene) in several mixed solvents (chlorobenzene-n-butyl alcohol, chlorobenzene-sec-butyl alcohol, chlorobenzene-Kerosene, chlorobenzene-methylketone) was studied using the capillary flow method. The velocity constant of scission reaction (K) and the limited degree of polymerization (g) were compared at the same value of [${\eta}$], which is considered as the parameter of molecular dimension of polymers in solution. As results, (K) did not change much, even if the species and the volume fraction of poor(non-) solvents changed, while the value of (g) changed according to the species of poor (non-) solvents and the value of [${\eta}$] these results were discussed.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.454-457
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• 2003

A new approach for groundwater treatment combines a permeable Fe(0) barrier to breakdown higher chlorinated solvents like PCE and TCE with a downgradient aerobic biological treatment system to biotransform less chlorinated solvents, such as DCE and vinyl chloride (VC). The expected bacterial performance downgradient of an Fe(0) barrier was evaluated through laboratory batch experiments with a toluene-degrading mixed culture that cometabolically transforms cis-1,2-DCE and VC. The amount of cis-1,2-DCE (initially at 2,000 ppb) and VC (initially at 2,000 ppb) transformed was controlled by the initial toluene (20,000 ppb) concentration. VC was removed much more effectively than Cis-1,2-DCE, and a higher toluene concentration in comparison to the co-substrate concentrations was needed for complete co-substrate removal. Overall, the coupling of an Fe(0) barrier and subsequent biodegradation appears feasible for remediation of complex mixtures of chlorinated solvents and petroleum hydrocarbons in groundwater

• 대한화학회지
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• 제17권3호
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• pp.207-212
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• 1973

毛細灌法을 利用하여 여러가지 混合溶媒系(dioxane-n-butanol, dioxane-sec-butanol, dioxane-ethyleneglycol, dioxane-kerosene)중에서 polyvinylacetate의 희박용액을 機械的으로 切斷하여 그 결과로 얻어진 平均切斷速度定數(k) 및 極限重合度(g)를 moleculare dimension이 동일한 조건하에서 比較검토하였다. 그 결과 k보다는 g의 값이 사용하는 solvent의 종류에 따라 크게 영향을 받음을 알았으며 이에 關하여 考察하였다.

• 폴리머
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• 제31권2호
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• pp.98-104
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• 2007

다양한 분자량의 폴리스티렌을 벤젠/n-헵탄, 1,4-다이옥산/이소프로판올, 1,4-다이옥산/n-헵탄과 같은 3종류의 혼합용매 계에 녹인 뒤 온도 상승에 따른 사슬의 팽창거동을 Flory $\Theta$온도 이상에서 점성도법으로 측정하였다. 온도 상승에 따라 두 종류의 영역, 즉 고분자 사슬이 팽창하는 영역과 수축하는 영역으로 구별되며, 분자량이 클수록 최대팽창온도가 높게 나타났다. 하나의 혼합용매 계 내에서는 $\tau/\tau_c$ 파라미터로 서로 다른 분자량의 사슬 팽창에 대하여 만능성이 나타나지만 서로 다른 혼합용매 계 사이에서는 각각의 기울기를 보임으로써 만능성이 관찰되지 않았다. 그러나 새로운 실험적 $b^{2/3}\tau/\tau_c$ 파라미터를 도입할 경우 모든 혼합용매 계의 사슬 팽창의 데이터들은 하나의 직선 위에 놓임으로써 만능성은 다시 회복되었다. 여기서 $\tau$는 $(T-\Theta)/\Theta$로 $\tau_c$는 $(\Theta-T_c)/T_c$로 각각 정의되며, $T_c$는 임계용액온도를 의미하며, b는 Schultz-Flory 식에서 $1/T_c$의 $1/M_w^{1/2}$에 대한 유효 기울기이다.

• 한국산업보건학회지
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• 제7권1호
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• pp.3-18
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• 1997

This study was conducted to evaluate desorption efficiencies by types of desorption solvent for polar and non-polar organic compounds collected on activated charcoal tubes. Analytes tested were toluene, m-xylene, isobutyl alcohol, n-butyl alcohol, cellosolve acetate, and butyl cellosolve. Three different concentration levels of spiked sample were made. Types of cosolvent mixed with the main solvent, $CS_2$, were methanol, pentanol, and dimethylformamide (DMF) and the cosolvent for methylenechloride was methanol. The amounts of cosolvent added to the main solvent were 1, 5, and 10% by volume (v/v%), respectively. The results were as follows: 1. For all mixed solvents except 1% methanol and 1% pentanol with $CS_2$, desorption efficiency significantly increased, compared with that of $CS_2$ alone. 2. Desorption efficiency increased by increasing analyte loading on charcoal tube regardless of mixed solvents used and the material polarity. 3. For all cosolvents mixed with $CS_2$ by 1% and 5% volume, desorption efficiency for non-polar compound was significantly higher than that of polar compound. For the 10% mixed solvents and the methylenechloride mixed with methanol, the results were opposite. 4. The lowest mean percent bias of 4.79% was obtained from the 5% DMF-$CS_2$ mixed solvent, followed by 4.82% from the 10% DMF-$CS_2$ solvent while the highest bias of 23.26% was from the solvent of $CS_2$ alone. Based on the results of this study, in order to increase desorption efficiency, it is recommended to add such cosolvents as methanol, pentanol, and DMF to $CS_2$, preferably 5% by volume for analyzing polar compounds collected in charcoal tubes.

• 멤브레인
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• 제25권1호
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• pp.48-59
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• 2015

순수용매와 혼합용매를 사용한 상전이를 통하여 poly(L-lactic acid) (PLLA) 스캐폴드 막을 제조하였다. 순수용매로서 chloroform과 1,4-dioxane을 사용하였으며, 이들 순수용매를 혼합하여 혼합용매를 제조하였다. 스캐폴드 막의 모폴로지, 기계적 특성 그리고, 물질전달 특성을 각각 SEM, 인장강도실험 및 당 확산실험을 통하여 측정, 평가하였다. 순수 chloroform 용매를 사용한 용액으로부터는 격벽-공극 구조(solid-wall pore structure)의 스캐폴드 막이 제조되었다. 반면, 순수 1,4-dioxane 용매를 사용한 용액으로부터는 나노섬유 구조의 스캐폴드 막이 제조되었다. 혼합용매의 경우 용매 내의 조성이 변화하면서 다양한 구조의 스캐폴드 막이 제조되었다. 혼합용매 내 1,4-dioxane 함량이 20% 이하인 경우에는 격벽-공극 구조의 스캐폴드 막이 제조되었으며, 1,4-dioxane 함량이 20%인 경우에는 최대직경 $100{\mu}m$의 거대공극을 갖는 구조를 보였다. 1,4-dioxane 함량이 25% 이상인 구간에서는 나노섬유 구조의 스캐폴드 막이 제조되었다. 이 구간에서는 혼합용매 내 1,4 dioxane 함량이 변화함에 따라 나노섬유의 직경이 함께 변화하였다. 나노섬유의 최소직경은 15 nm 가량이었으며, 혼합용매 내의 1,4-dioxane 함량이 80 wt%일 때에 얻어졌다. 이상의 결과를 통하여 용매의 조성은 스캐폴드 막의 구조를 결정짓는 중요한 요소가 된다는 결론을 얻을 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3267-3273
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• 2011

Ag(I) carboxylate gelators with mixed-ligands were systemically investigated to understand the mechanism of the organic gel formation. The gelators constructed 3-D networks of nanometer-sized thin fibers which facilitated gel formation in various aromatic organic solvents, even at very low concentrations. The loss of reflection peaks in the X-ray diffraction data indicated the reduction of strong interactions between the long alkyl chains as the Ag(I) carboxylates formed gels by maximizing their interactions with the organic solvents. The gelation temperature ($T_{gel}$) was measured to explore the interaction between the gelator molecules and solvents depending on their composition and concentration. Based on the gelation phenomena, a dissociation/re-association mechanism was proposed.

• 한국포장학회지
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• 제9권1호
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• pp.1-6
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• 2003

The partitioning behavior of five printing ink solvents was studied in various cookie ingredients before and after baking which had different water content and different structure. Solvents were ethyl acetate, hexane, isopropanol, methyl ethyl ketone, and toluene which represent different characteristic functional groups. Gas chromatography (G.C.) was used to measure partitioning values at $25^{\circ}C$ on each raw and baked cookie ingredients. Baking condition of cookie ingredients was $260^{\circ}C$ for 10 min. In cookie ingredients, decreases in water content generally affected Kp of polar solvents, but did not affect that of the non-polar solvents. However, as water content decreased in the cookie ingredient, the Kp of the non-polar and polar solvents showed mixed results.

• 한국의류산업학회지
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• 제7권6호
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• pp.680-688
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• 2005

This study was carried out to investigate on the removal of oily and particulate soils from silk fabrics. Various kinds of solvents were used on the removal of two kinds of soils treated into the silk fabrics. The removal of oily soil was analyzed by liquid scintillation counting method, and the removal of oil and carbon particulate mixed soils was evaluated by measuring of reflectance on the surface of soiled fabrics with/without drysoap in solvent washing by Terg-o-tometer. The surfaces of fabrics were also observed by SEM before and after washing. The results obtained were as follows : oily soils were removed efficiently by various kinds of solvents regardless of kinds of silk fabrics in short washing time. The removal effect of solvents from the soiled silk fabrics were high in the order of isopropyl alcohol>trichloroethane>monochlorobenzene>ethylether>perchloroethylene. Oil and carbon particulate mixed soils could be efficiently removed by adding of drysoap in solvent washing. The removal of mixed soils were increased drastically with rinsing and increased drysoap. The removal of soils was more efficiently removed from degummed silk fabrics than from the raw silk fabrics.

• 분석과학
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• 제8권4호
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• pp.481-486
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• 1995

Quenching experiments by photoinduced electron transfer between a charged donor and a neutral acceptor were carried out in acetonitrile, dichloromethane and mixed solvents of acetonitrile and dichloromethane. Tris(2, 2'-bipyridine) ruthenium(II) ($[Ru(bpy)_3]^{2+}$) which has 2+ charge and dicyanobis (2, 2'-bipyridine) ruthenium(II) ($Ru(bpy)_2(CN)_2$) which has no charge were used as electron donors, and a series of tris(${\beta}$-diketonato) ruthenium (III) was used as acceptor. In dichloromethane, $[Ru(bpy)_3]^{2+}$ and its counter ions ($ClO{_4}^-$) form ion pair. In the estimate of ${\Delta}G$ of electron transfer, the electrostatic potential between counter ions and product ion pair produced by electron transfer must be taken into account. A similar effect of counter ions was found in mixed solvents of 10, 30, 50, 70 and 90% acetonitrile ratio in volume. The effect of counter ion on ${\Delta}G$ became smaller with the increase in acetonitrile ratio. The result in mixed solvents suggests that $[Ru(bpy)_3]^{2+}$ and its counter ions form ion pair even in 90% acetonitrile solution.