• Journal of the Korean Applied Science and Technology
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• v.28 no.4
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• pp.386-392
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• 2011

We are crystallized to the linear low density polyethylene(LLDPE) particles by a thermally induced phase separation(TIPS). TIPS process based on the phase separation mechanism was performed for the LLDPE system which undergoes liquid-solid phase separation. The linear low density polyethylene particle formation occurred by the nucleation and growth mechanism in the metastable region. Although the growth rates depended on the experimental conditions such as the polymer concentration and temperature, the particles were larger when the polymer concentration was higher or temperature was higher. The particles were observed by SEM. The LLDPE particle size distribution became broader when the polymer concentration was higher.

• 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.

• Journal of the Korean Applied Science and Technology
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• v.28 no.3
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• pp.306-312
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• 2011

In this study, we are crystallized to the low density polyethylene (LDPE) micro-particles in $n$-dodecanol solution by thermally induced phase separation(TIPS) method. The Low density polyethylene micro-particles is used in a wide variety of polymer coatings and industrial application. The utility of that for a particular application depends on a number of factors such as the particle size and distribution, and chemical composition of the materials. However, there are still needs for new methods of preparation which will provide the structure with unique sizes. The widely used processes for micro-size particles are crystallization method and thermally induced phase separation. TIPS process based on the phase separation mechanism was performed for the LDPE system which undergoes liquid-solid phase separation. Effects of various operating parameters were examined on the structure variation of the particles. Professionality, take-up speed and crystallization rate depended on temperature and concentration of polymer in solution.

• Textile Coloration and Finishing
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• v.15 no.4
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• pp.57-64
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• 2003

Poly(ethylene-co-vinyl acetate)(EVA) microspheres were prepared by a thermally induced phase separation. The microsphere formation occurred by the nucleation and growth mechanism in the metastable region. The diluent used was toluene. The microsphere formation and growth was followed by the cloud point of the optical microscope measurement. The microsphere size distribution, which was obtained by SEM observation and particle size analyzer, became broader when the polymer concentration was higher, the content of vinyl acetate in EVA copolymer was higher, and the cooling rate of EVA copolymer solution was lower.

• 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.

• Proceedings of the Membrane Society of Korea Conference
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• 1992.10a
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• pp.41-42
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• 1992

고내열 및 고내화학적 특성을 갖는 미세다공성 고분자막의 개발을 위한 기초연구가 수행되었다. 본 연구에서는 고분자막 제조기법의 첨단기술로 등장한 열유도상 분리공정(Thermally Induced Phase Separation, 이하 TIPS)이 도입되었다. TIPS 공정은 고분자를 고분자의 용융점을 상회하는 온도에서 매우 미세하게 분산시킬 수 있는 희석제를 고분자와 함께 melt-blending하여 균일한 single phase의 용액을 만들고 이를 적당한 막의 형태로 성형한 후, 가해진 열을 제거하여 냉각시킴에 따라 polymer-rich phase 와 polymer-poor phase 로 구성되는 two phase system으로 상분리를 일으키는 방법이다. 이때 polymer-poor phase를 차지하는 희석제를 제거함에 따라 고분자 matrix 내에는 void volume이 형성되고, 그 결과 고분자 matrix 전체적으로 다공성이 부여되어 고분자막으로서의 기본적인 기능을 갖추게 된다.

• Polymer(Korea)
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• v.26 no.6
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• pp.821-828
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• 2002

Regular and highly interconnected macroporous poly(L-lactic acid) (PLLA) scaffolds with pore size of 10∼300 ㎛ were fabricated through thermally induced phase separation of a PLLA-dioxane-water ternary system in the presence of a small amount of Pluronics. Addition of Pluronics to the ternary system raised the cloud-point temperature curve in the order of P-123< F-68< F-127. The Pluronics act as nuclei for the phase separation. This assistance is enhanced with increasing length of the hydrophilic PEO blocks in the Pluronics molecules. Liquid-liquid spinodal phase separation was induced at higher temperatures in the systems containing Pluronics because the spinodal region is raised to higher temperature. The absorption of Pluronics onto the interface stabilizes a macro scale structure and increases the interconnection of pores.

• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.942-952
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• 2013

Monoliths are functional porous materials with a three-dimensional continuous interconnected pore structure in a single piece. A monolith with uniform shape based on poly(${\gamma}$-glutamic acid) (PGA) has been prepared via a thermally induced phase separation technique using a mixture of dimethyl sulfoxide, water, and ethanol as solvent. The morphology of the obtained monolith was observed by scanning electron microscopy and the surface area of the monolith was evaluated by the Brunauer Emmett Teller method. The effects of fabrication parameters such as the concentration and molecular mass of PGA and the solvent composition have been systematically investigated. The PGA monolith was cross-linked with hexamethylene diisocyanate to produce the water-insoluble monolith. The addition of sodium chloride to the phase separation solvent affected the properties of the cross-linked monolith. The swelling ratio of the cross-linked monolith toward aqueous solutions depended on the buffer pH as well as the monolith fabrication condition. Copper(II) ion was efficiently adsorbed on the cross-linked PGA monolith, and the obtained copper-immobilized monolith showed strong antibacterial activity for Escherichia coli. By combination of the characteristic properties of PGA (e.g., high biocompatibility and biodegradability) and the unique features of monoliths (e.g., through-pore structure, large surface area, and high porosity with small pore size), the PGA monolith possesses large potentials for various industrial applications in the biomedical, environmental, analytical, and separation fields.

• Proceedings of the Membrane Society of Korea Conference
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• 2001.11a
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• pp.96-99
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• 2001

• Membrane Journal
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• v.28 no.6
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• pp.395-405
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• 2018

Poly(ethylene-co-vinylalcohol) EVOH hollow fiber membranes were successfully fabricated via a thermally induced phase separation (TIPS) method. It was observed that all membranes fabricated under different spinning conditions had interconnected and bicontinuous structures through liquid-liquid phase separation. Glycerol and poly(ethylene glycol) 200 were used as diluents for the TIPS method. Glycerol was used as a mixing component in quenching bath to control pores on the outer surface of the hollow fiber membrane. Hot quenching bath with a mixing component to generate large pores on the outer surface of the hollow fiber membrane. The effects of polymer concentration, diluent and quenching bath on the morphologies, water permeabilities, and mechanical properties of the EVOH hollow fiber membranes were systematically investigated. The relationship between water permeability, mechanical properties and spinning conditions was discussed in detail.