Induced Phase Separation (induced + phase_separation)

Distribution by Scientific Domains

Selected Abstracts

Janus Supraparticles by Induced Phase Separation of Nanoparticles in Droplets

Rhutesh K. Shah
Biphasic Janus particles with a precisely tunable internal morphology are fabricated using a novel, versatile, and robust technique. This technique can be used in conjunction with microfluidics to produce monodisperse particles, or can be combined with bulk emulsification techniques to produce large quantities of particles. [source]

Rheology behavior of high-density polyethylene/diluent blends and fabrication of hollow-fiber membranes via thermally induced phase separation

Jianli Wang
Abstract The phase-separation behavior of high-density polyethylene (HDPE)/diluent blends was monitored with a torque variation method (TVM). The torque variation of the molten blends was recorded with a rheometer. It was verified that TVM is an efficient way to detect the thermal phase behavior of a polymer,diluent system. Subsequently, polyethylene hollow-fiber membranes were fabricated from HDPE/dodecanol/soybean oil blends via thermally induced phase separation. Hollow-fiber membranes with a dense outer surface of spherulites were observed. Furthermore, the effects of the spinning temperature, air-gap distance, cold drawing, and HDPE content on the morphology and gas permeability of the resultant membranes were examined. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Effect of the preparation conditions on the permeation of ultrahigh-molecular-weight polyethylene/silicon dioxide hybrid membranes

Nana Li
Abstract Porous ultrahigh-molecular-weight polyethylene/SiO2 membranes were prepared by thermally induced phase separation (TIPS) with white mineral oil as the diluent and SiO2 as an additive. Influential factors, including extraction method, SiO2 content, and cooling rate, were investigated. The results suggest that the both porosity and pure water flux of the membranes by extraction of the solvent naphtha in the tension state with alcohol were the best among our research. With increasing SiO2 content, the porosity, pure water flux, and pore diameter increased. However, with excessive SiO2 content, defects formed easily. Moreover, SiO2 improved the pressure resistance of the membranes. The cooling rate directly effected the crystal structure. A slow cooling rate was good for crystal growth and the integration of the diluent. Therefore, the porosity, pure water flux, and bubble-point pore diameter increased with decreasing cooling rate. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

A new technique for foaming submicron size poly(methyl methacrylate) particles

Hiroyuki Ogawa
Abstract About 0.7,2 ,m diameter poly (methyl methacrylate) (PMMA) foamed particles were prepared via thermally induced phase separation (TIPS) from a PMMA/ethanol mixture and vacuum dried. It was found that ethanol, known to be a poor solvent to PMMA, could dissolve PMMA when the temperature was over 60C. The solubility of PMMA (Mw = 15,000 and Mw = 120,000) in ethanol was measured and was found to increase as the temperature increased. PMMA particles on the scale of submicron and single micron diameter could be precipitated from the PMMA/ethanol solution by temperature quenching. Then, since the precipitated particles contained a certain amount of ethanol, the precipitated particles could be foamed using the ethanol as a foaming agent in a vacuum drying process. Vacuum drying at temperatures slightly below the glass transition temperature of the polymer could make the particles foam. The effects of foaming temperature and the molecular weight of the polymer on the size of foamed particles were investigated. The experimental results showed that the vapor pressure and the molecular weight of the polymer are key factors determining the expandability of the micro particles. 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

Preparation and properties of poly(L -lactic acid) scaffolds by thermally induced phase separation from a ternary polymer,solvent system

Shirong Li
Abstract Poly(L -lactic acid) (PLLA) foams for tissue engineering were prepared via thermally induced phase separation of a ternary system PLLA/dioxane/tetrahydrofuran (THF) followed by double solvent exchange (water and ethyl alcohol) and drying. An extension to solidification from solution of a previously developed method for solidification from the melt was adopted. The technique is based on a continuous cooling transformation (CCT) approach, consisting in recording the thermal history experienced by rapidly cooled samples and then analyzing the resulting sample morphology. Different foams were produced by changing the relative amount of dioxane and THF in the starting solution while the amount of polymer was kept constant. Results show that the final morphology and crystallinity (measured by DSC) depend on solvent power, which in its turn was determined by the ratio dioxane/THF, and a minimum of pore size, optimum final crystallinity and crystallization rate were achieved for a system containing 70 % of dioxane. Under this condition, a higher bulk density (evaluated by Hg intrusion porosimetry) and a larger specific surface area (measured by BET N2 sorption technique) was achieved. Copyright 2004 Society of Chemical Industry [source]