• Title/Summary/Keyword: temperature separation

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PREPARATION OF POLY(ETHYLENE-CO-VINYL ALCOHOL) MEMBRANE VIA THERMALLY INDUCED PHASE SEPARATION

  • Matsuyama, Hideto;Shang, Mengxian;Teramoto, Masaaki
    • Proceedings of the Membrane Society of Korea Conference
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    • 2004.05a
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    • pp.74-77
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    • 2004
  • Porous membranes were prepared via thermally induced phase separation (TIPS) of (ethylene-co-vinyl alcohol) (EVOH)/glycerol mixtures. The liquid-liquid (L-L) phase boundaries are shifted to higher temperature when the ethylene contents in EVOH increase. Moreover, the kinetic study proved that the growth of droplets formed by the general liquid-liquid (L-L) phase separation obeyed a power-law scaling relationship in the later stage of spinodal decomposition (SD). A new phase separation mechanism was presented, in which the L-L phase separation could be resulted from the crystallization. The hollow fiber membranes were prepared. The membranes showed asymmetric structures with skin layer near the outer surface, the larger pores just below the skin layer and the smaller pores near the inner surface. The effect of ethylene content (EC) in EVOH, cooling water bath temperature and take-up speed on membrane performance was investigated.

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A Study on Separation of $N_2-SO_2$ Mixed Gas by Polymer Membranes (고분자막을 이용한 $N_2-SO_2$ 혼합기체의 분리에 관한 연구)

  • 김성준;민병렬;이태희
    • Membrane Journal
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    • v.2 no.2
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    • pp.135-143
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    • 1992
  • Separation of $N_2-SO_2$ mixed gas by polymer membranes, SEPA-97(CA), TFC, and FT-30 membrane, was investigated by varying pressure and temperature. The permeability coefficients and the separation factors of mixed gases were measured, and the influence of various factors on the gas permeability characteristics and separation performance were investigated. The range of pressure was 0.1~1.0 MPa, and that of temperature was 283~303 K. The experimental results showed that the permeability coefficients and the separation factors were increased with an increase in pressure, but they were deereased with increasing temperature. Among the examined membranes, FT-30 possessed the best gas-separating characteristics.

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Studies on the Phase Separation of the Borosilicate Glass by Addition of Titanium Dioxide ($TiO_2$ 첨가에 따른 붕규산 유리의 분상에 관한 연구)

  • 박용완;민병욱
    • Journal of the Korean Ceramic Society
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    • v.18 no.4
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    • pp.257-261
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    • 1981
  • The tendency of glass containing titanium-dioxide to separate into two phases can be attributed to a change of the coordination number of titanium from six to four on increase of temperature and to "freezing" of the high temperature four fold coordination on cooling of the melt. Addition of TiO2 to the basic glass 8.7 $Na_2O$ 22.4B2O3 68.9 $SiO_2$ was varied 5 to 25 parts. The phase separation in the temperature range of transformation was examined with each heating temperature and soaking time. As the experimental results, the most distinct phase separation were obtained from alkali extraction method when $TiO_2$ was added 15 parts. The apparant activation energy was 30.5 Kcal/mole by alkali extraction method derived from Arrhenius plots.ius plots.

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Preparation of Porous Glasses by the Phase-separation of the Silicate Glass Containing $TiO_2$ ($TiO_2$를 함유한 규산염 유리의 상분리를 이용한 다공질 유리의 제조)

  • 김병훈;최석진;박태철
    • Journal of the Korean Ceramic Society
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    • v.28 no.1
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    • pp.29-36
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    • 1991
  • Microporous glasses in the system TiO2-SiO2-Al2O3-B2O3-CaO-Na2O were prepared by the phase-separation technique. Morphology and distribution of pore and specific surface area of glasses heated and leached out at various conditions were investigated by SEM and Porosimeter. Crystallization of glasses heated above transition temperature was also inspected by X-ray diffraction method. When the heating temperature and time increased, the pore size and volume increased, but the specific surface area decreased above the critical temperature. The phase-separation, specific surface area and pore size showed more sensitive change on the variation of heating temperature than of heating time. The specific surface area and micropore volume of porous glasses prepared in this study were about 120-330$m^2$/g and 0.001-0.01cc/g, respectively. Mean pore size of porous glasses were about 20-90$\AA$. Anatase phases was deposited when the parent glass was heat-treated at 75$0^{\circ}C$ for 6hrs.

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Spinodal Phase Separation and Isothermal Crystallization Behavior in Blends of VDF/TrFE(75/25) Copolymer and Poly(1,4-butylene adipate) (I) -Spinodal Phase Separation Behavior-

  • Kim, Kap Jin;Kyu, Thein
    • Fibers and Polymers
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    • v.4 no.4
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    • pp.188-194
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    • 2003
  • Phase behavior and spinodal phase separation kinetics in binary blends of a random copolymer of vinylidene fluoride and trifluoroethylene (75/25) [P(VDF/TrFE)] and poly(l,4-butylene adipate) (PBA) have been investigated by means of optical microscopic observation and time-resolved light scattering. The blends exhibited a typical lower critical solution temperature (LCST)∼${34}^{\circ}C$ above the melting temperature of the P(VDF/TrFE) crystals over the entire blend composition range. P(VDF/TrFE) and PBA were totally miscible in the temperature gap between the melting point of P(VDF/TrFE) and the LCST. Temperature jump experiments of the 3/7 P(VDF/TrFE)/PBA blend were carried out on a light-scattering apparatus from a single-phase melt state (${180}^{\circ}C$) to a two-phase region (205∼${215}^{\circ}C$). Since the late stage of spinodal decomposition (SD) is prevalent in the 3/7 blend, SD was analyzed using a power law scheme. Self-similarity was preserved well in the late stage of SD in the 3/7 blend.

Adsorption Properties of Ca-exchanged Clinoptilolite under Low-temperature (Ca 이온교환 Clinoptilolite의 저온 흡착 특성)

  • Song Taek-Yong;Lee Young-Chul;Baek Young-Soon;Kim Jong-Nam
    • Journal of the Korean Institute of Gas
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    • v.8 no.4 s.25
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    • pp.36-41
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    • 2004
  • The breakthrough curve was obtained to evaluate separation efficiency of clinoptilolite as an methane/nitrogen separation adsorbent. The Ca-exchanged clinoptilolite showed improved separation efficiency. The nitrogen adsorption capacity of Ca-clinoptilolite was increased with decreasing temperature. The temperature was decreased from 293K to 253K(feed gas flow rate : 670ml/min, pressure : 333kPa). The adsorption capacity is increased with increasing pressure. The pressure was increased from 333kPa to 700kPa(feed gas flow rate : 670ml/min, temperature : 253K, 293K).

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The Effect of Temperature and Flow Rate of Eluent on the Separation of Adjacent Lanthanides (La : Ce, Ce : Pr, Pr : Nd) with Displacement Chromatography (치환크로마토그래피에서 온도와 용리액의 흐름속도가 란탄족 원소들 (La : Ce, Ce : Pr, Pr : Nd) 의 분리에 미치는 영향)

  • Ha, Yeong Gu;Song, Gi Hun
    • Journal of the Korean Chemical Society
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    • v.38 no.9
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    • pp.660-666
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    • 1994
  • The effects of temperature and flow rate of eluent on the separation of adjacent lighter lanthanide pairs (La : Ce, Ce : Pr, Pr: Nd) have been studied with displacement chromatography. Two serial columns packed with Amberlite 120 cation exchange resin are used for loading and separation. The retaining ion is $H^+$ ion and the eluent is 0.012M and 0.015M of EDTA solution. The columns and the eluent are maintained at the temperature of 90$^{\circ}C$ and pressurized to reduce vaporizing in the ion-exchange resin column. The eluated solution is analyzed directly with ICP-AES. The separation factors of the lanthanide pairs, La: Ce, Ce :Pr, and Pr: Nd, are 4.6, 2.8, and 1.9, respectively and are higher than that from theoretical calculation at 25$^{\circ}C$. When the flow rate is reduced from 2.5 ml/min to 1.5 ml/min, the HETP is reduced from 1.60 cm to 0.88 cm. The separation efficency can be improved at lower flow rate of eluent and higher operating temperature. The recoveries of pure lanthanides than 99.9% are 49∼77% from this separation.

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Pervaporation Separation Characteristics for Water-Ethanol Mixtures Using Porous Hollow Fiber PVA Composite Membranes (미세 다공성 중공사 PVA복합막을 이용한 에탄올 수용액의 투과증발분리 특성)

  • Kim, Ji Seon;Park, Hun Whee;Seo, Chang Hee;Rhim, Ji Won
    • Membrane Journal
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    • v.23 no.5
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    • pp.360-366
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    • 2013
  • The Poly (vinylidene fluoride) and poly (acrylonitrile) (PAN) hollow fiber composite membranes coated with poly (vinyl alcohol) (PVA) and poly (acrylic acid) (PAA) as the crosslinkig agent are prepared. The resulting membranes were characterized for aqueous 90 wt% ethanol solution by pervaporation techniques in terms of the permeability and separation factor. In general, as both the crsslinking reaction temperature and the crosslinking agent concentration increase, the permeability decrease while the separation factor tends to increase. And also the permeability increased and the separation factor decreased as the feed temperature increased. Typically, the permeability $502g/m^2hr$ at the feed temperature $70^{\circ}C$ was obtained for PVDF hollow fiber membrane prepared with the crosslinking agent PAA 3 wt% at the reaction temperature $60^{\circ}C$ whereas the separation factor 218 was shown for the membrane reacted with PAA 11 wt% and at $100^{\circ}C$ for the feed temperature $50^{\circ}C$.

Structural Changes of PVDF Membranes by Phase Separation Control (상분리 조절에 의한 PVDF막의 구조 변화)

  • Lee, Semin;Kim, Sung Soo
    • Korean Chemical Engineering Research
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    • v.54 no.1
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    • pp.57-63
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    • 2016
  • Thermally induced phase separation (TIPS) and nonsolvent induced phase separation (NIPS) were simultaneously induced for the preparation of flat PVDF membranes. N-methyl-2-pyrrolidone (NMP) was used as a solvent and dibutyl-phthlate (DBP) was used as a diluent for PVDF. When PVDF was melt blended with NMP and DBP, crystallization temperature was lowered for TIPS and unstable region was expanded for NIPS. Ratio of solvent to diluent changed the phase separation mechanism to obtain the various membrane structures. Contact mode of dope solution with nonsolvent determined the dominant phase separation behavior. Since heat transfer rate was greater than mass transfer rate, surface structure was formed by NIPS and inner structure was by TIPS. Quenching temperature of dope solution also affected the phase separation mechanism and phase separation rate to result in the variation of structure.

Behaviors of Ionic Conductivity with Temperature for High-Temperature PEMFC Containing Room Temperature ionic Liquids Under Non-humidified Condition (상온 이온액을 이용한 고온 무수 PEMFC용 고정화 액막의 온도에 따른 이온전도도 거동)

  • Kim, Beom-Sik;Byun, Yong-Hoon;Park, You-In;Lee, Sang-Hak;Lee, Jung-Min;Koo, Kee-Kahb
    • Membrane Journal
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    • v.16 no.4
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    • pp.268-275
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    • 2006
  • Novel SILEMs were prepared by multi-stage phase separation process combined by the low temperature phase separation (LTPS) and the high temperature phase separation (HTPS) using room temperature ionic liquids (RTILs) which have a high ionic conductivity. PVDF and imidazolium series ionic liquids were used as membrane material and electrolyte, respectively. To study the ion conducting properties, the SILEMs were tested using LCR meter at temperature controlled from 30 to $130^{\circ}C$. Under humid conditions, with increasing temperature from 30 to $100^{\circ}C$, the ion conductivity of the cast $Nafion^{(R)}$ membrane increased linearly, but then started to decrease after $100^{\circ}C$. However, in the case of the SILEMs, with increasing operating temperature, the ion conductivity increased. Also, the ion conductivity behaviors of the SILEMs were almost same, regardless of humidity. The ion conductivity of the SILEMs was $2.7{\times}10^{-3}S/cm$ and increased almost linearly up to $2.2{\times}10^{-2}S/cm$ with increasing temperature to $130^{\circ}C$. The effects of an inorganic filler on the physical properties of the SILEMs were studied using the $SiO_2$. The addition of $SiO_2$ could improve the mechanical strength of the SILEMs, though the ionic conductivity was decreased slightly.