• 한국에너지공학회:학술대회논문집
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• 한국태양에너지학회, 한국에너지공학회 1993년도 춘계 공동학술발표회 초록집
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• pp.126-131
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• 1993

Differential Scanning Calorimetry (DSC) and solvent swelling technique have been applied for identifying physical transition temperatures in the macromolecular structure of coals. The transition processes seem to be associated with physical relaxation of the coal structure and are irreversible processes. In Pittsburgh No. 8 high volatile bituminous (hvb) coat one physical transition was noted at 250-30$0^{\circ}C$ (at 8$^{\circ}C$/min) without any significant accompanying weight loss. Coals of higher rank than high volatile bituminous, i.e., Upper Freeport medium volatile bituminous (mvb) and Pocahontas No.3 low volatile bituminous (lvb) coals, exhibit structural relaxation just before the major thermal decomposition process and a sharp increase in solvent swellability accompanies this relaxation. In the case of both the Pittsburgh No.8 and the Upper Freeport coat structural relaxations at around 36$0^{\circ}C$ seem to coincide with release of "guest molecules".les".uot;.

• 한국염색가공학회지
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• 제15권4호
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• pp.8-16
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• 2003

Poly(trimethylene terephthalate)(PTT) fiber was pretreated with organic solvent/water solution of various compositions. The organic solvents used in this experiment were benzyl alcohol, n-buthanol, and N,N-dimethylformamide(DMF). Density of the fibers were investigated as a measure of crystallite region. The dye uptake increased in the order of pretreatment with hot water < untreated < 5% benzyl alcohol < 100% benzyl alcohol < 90% benzyl alcohol; hot water < untreated $\risingdotseq$ 5% butanol < 100% beutanol < 90% butanol; hot water $\risingdotseq$ 5% DMF < untreated < 90% DMF < 100% DMF. The dye uptake increases with increase of crystallinity. It seems likely that the recrystallization process during the pretreatment with organic solvent/water solutions leads to an increase in the microvoid and then a large increase in the dye uptake. Also the dyeing rate increased and the dyeing transition temperature decreased with the pretreatments. The results obtained are corresponds with the plasticization of the fiber structure formed during the pretreatrnent.

• 약학회지
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• 제39권6호
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• pp.593-599
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• 1995

Erythromycin was formulated as enteric-coated pellets in order to reduce degradation in stomach and gastromtestmal irritation, and to maximize the absorption in intestine followmg its oral administration. Core pellets were prepared using fluid-bed granulator with two different methods (powder layering and solvent spraying) and enteric-coated with two different coating polymers (HPMCP and Eudragit E30D). Physical characteristics md dissolution rates of core pellets and enteric-coated pellets were evaluated to optimize the formulation. Powder layering method resulted in shorter initial dissolution time than solvent spraying method, but physicochmical properties of the product were worse than solvent spraying method with respect to hardness, ftiability and density. The dissolution rate of the drug was increased with the addition of surfactants, showing concentration-dependence. The scanning electron microscopic observation of pellets revealed significant differences on the surface appearances prepared with solvent spraying method. The core pellet made with powder layering method had crystals on the surface, which resulted in poor physical properties of the pellets. The dissolution profiles of erythromycin pellets coated with HPMCP or Eudragit L30D were close to that of commercially available erythromycin enteric-coated product.

• 한국염색가공학회지
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• 제17권5호
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• pp.1-12
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• 2005

Polyester fibers can be modified into cationic dyeable polyester fibers(CDP) by the copolymerization of terephthalic acid and 5-sodium sulphoisophthalic acid with ethylene glycol. The advantage of CDP on most cationic dyes is the conspicuous brilliance due to a narrow steep absorption band and the wash fastness and etc. Weight reduction by alkali hydrolysis, dyeing and solvent wicking properties of fabrics with cationic dyes, and change of fine structure were investigated. To obtain optimum splitting process parameters for dyeing and physical properties of micro CDP fiber, splitting method under various conditions was carried out. By means of SEM, it was confirmed that the splitting process of the micro CDP fiber be achieved at the weight reduction. A comparatively greater quantity of dye is necessary to dye microfiber than conventional fiber. The fastness and solvent wicking of regular CDP fiber is higher than that of micro CDP fiber.

• Bulletin of the Korean Chemical Society
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• 제15권3호
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• pp.214-221
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• 1994

We present some results obtained from theoretical study on a non-symmetrical A/BC polymeric system including solvent which consists of two phases, a polymeric phase A on one side and a mixture of polymers B (as a compatibilizer) and C on the other in the presence of a solvent. By employing the functional integral techniques we derive the mean-field equations and solve them numerically to deduce the physical properties of the interface involving the polymers and solvent concentration profiles in the limit that molecular weights of all the polymers involved tend to infinity. The calculations are performed for typical values of the Flory interaction parameters and for the volume fraction of polymer B in the asymptotic phase and of solvent. In the polymers/solvent blend under consideration the interfacial adsorption of polymer B, the solvent concentration, and degrees of the specific interaction between the polymers are found to play important roles in modification of the interfacial properties.

• 한국식품과학회지
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• 제21권6호
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• pp.851-856
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• 1989

추출방법을 달리하여 얻은 육두구 정유에 대한 물리적 성질을 측정하고, GC와 GC/MS를 이용하여 분석하였다. 추출수율은 용매추출이 23%로 가장 많았고 SDE 추출, $CO_2$ 추출순이었다. 육두구유에 대한 물리적 성질과 GC분석결과에서 본 실험에 사용한 육두구는 East Indies type에 가까운 것을 확인할 수 있었고 각각 추출물의 분석결과로부터 sabinene은 3.6-14.1%, miristicin은 28.4-48.7% elemicin은 1.2-2.1%이 함유되어 있음을 알 수 있었다. 또 발암물질로 알려진 safrole은 SDE 추출에서 3.8%, 용매추출에서 3.6%, $CO_2$추출에서 5.6% 함유하고 있는 것으로 나타났다. SDE 추출이나 용매추출에서 확인된 camphene은 $CO_2$추출에서 확인할 수 없었고 monoterpene, terpene alcohol 계통의 화합물은 SDE 추출이나 용매 추출에 많았다. 방향족 화합물은 $CO_2$추출에서 많이 추출됨을 확인할 수 있었다.

• Elastomers and Composites
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• 제29권3호
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• pp.226-233
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• 1994

The properties of the mixed prepolymer-urethane in the range of 10-40 phr were observed. LBR and LCR have same functional group but different in structure of molecular. The viscosity of mixture depending on content of rubber, adhesive strength, thermal property and compatibility with a diluted solvent are as follows: 1. The viscosity of the mixture was influenced by solubility of the diluent for urethane resin and liquid rubber. 2. Adhesive strength showed the highest value at 30phr rubber, decreased gradually at above 30phr rubber. And LBR revealed better physical property than that of LCR. 3. The most effective factors affecting adhesive strength are molecular structure of rubber, the type of solvent, and volatility. 4. Urethane resin containing LBR showed better compatibility for solvent and faster drying velocity. 5. LBR showed more favorable compatibility and dispersion state than those of LCR by analyzing the results of SEM.

• 한국환경과학회지
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• 제7권6호
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• pp.753-759
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• 1998

In physical and reactive extraction of acrylic acid using various solvents the equilibrium characteristics of extraction were investigated. The degree of extraction in reactive extraction with Tri-n-octylamine(TOA) was 1.5~3 times than that in physical extraction. Distribution ratio was constant in methyl isobutyl ketone(MIBK) and n-butylacetate(n-BAc) but was increased with increasing the concentration of acrylic acid in benzene and chloroform. It can be explained by formation of dimers. Maximum extraction leadings of acrylic acid were three in benzene and were two in MIBK, chloroform and n-BAc, and it was found that acrylic acid was extracted as the form of $A_3$R In benzene and $A_2R$ in MIBK, chloroform and n-BAc. In effect of solvent, the degree of extraction was increased as he difference of solubility parameter of solvent and solute was decreased, and as dielectric constant of solvent was increased.

• 한국군사과학기술학회지
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• 제4권1호
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• pp.216-224
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• 2001

HNS(hexanitrostilbene), one of the most important heat resistant explosive was recrystallized using organic solvent, nitric acid and dual solvent system of acetonitrile-toluene. The purification, analysis, type conversion method and its physical properties are described.

• 대한화학회지
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• 제57권5호
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• pp.599-605
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• 2013

Some N-acetyl pyrazoles including 1-(3-(3,4-dichlorophenyl)-5-(substituted phenyl)-4,5-dihydro-$^1H$-pyrazole- 1-yl) ethanones have been synthesised by solvent free cyclization cum acetylation of chalcones like substituted styryl 3,4- dichlorophenyl ketones using hydrazine hydrate and acetic anhydride in presence of catalytic amount of fly-ash: $H_2SO_4$ catalyst. The yield of these N-acetyl pyrazole derivatives are more than 75%. The synthesised N-acetyl pyrazoline derivatives were characterized by their physical constants and spectral data.