Papers by Keyword: Phase Inversion

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Authors: Li Yang, Yun Peng An, Nan Tian, Jun Ma, Jian Hua Yao
Abstract: In order to reduce the flow resistance of a water-based drilling fluid, emulsifiers tend to be added into the drilling fluid mixed with oil at the same time. However, inappropriate proportion or oil-based pipe free agent with low HLB value could easily trigger the phase inversion of the drilling fluid, causing its stability loss or even water–solid separation. Therefore, starting from the root cause of the phase inversion, the surfactivity of solid-phase materials in the drilling fluid was changed from hydrophobicity to hydrophilicity by adding surfactants with high HLB value. Then its colloidal properties were reestablished by combining alkali diluting agent, and the drilling fluid with phase inversion of well Lianhua 000-X2# was treated indoors. The results of the field application in the well show that high-HLB surfactant can solve the phase inversion of a water-based drilling fluid properly, and that barite sedimentation and well control problem, caused by the phase inversion of the water-based drilling fluid with high-density, can be avoided.
Authors: Keila Machado Medeiros, Diego Farias Lima, Carlos Antônio Pereira de Lima, Edcleide Maria Araújo, Hélio Lucena Lira, Vanessa Nóbrega Medeiros
Abstract: Membrane is a barrier that separates two phases and limits wholly or partially carrying one or several chemical species present in the phases. In this study, membranes with a polyamide6 porogenic agent were obtained. The membranes were prepared as thin films by phase inversion method using the immersion technique, precipitation by varying the percentage of porogenic agent introduced and the time of exposure of the membranes during the process of immersion-precipitation. The membranes obtained were characterized by scanning electron microscopy (SEM). From the SEM photomicrographs, a large morphological change was observed over the entire surface layer of the membranes, significantly affecting the size and number of pores. Furthermore, porogenic agent promoted the formation of pores and the increase in planar microporous membranes obtained.
Authors: Zawati Harun, Sitikhadijah Hubadillah, Sulaiman Hasan, Muhamad Zaini Yunos
Abstract: In this present work, the effects of phase inversion ceramic membranes prepared by phase inversion were investigated. Kaolin with 25µm was used as the composition of membrane preparation. The amounts of kaolin investigated were 60g, 70g and 80g respectively while the temperature was conducted assist room temperature and 3°C. Non-solvent additive with 6g distilled water present formation of pore during phase inversion.The effects of phase inversion temperature and kaolin composition on morphology and porosity were investigated in detail. Result of porosity showed that by decreasingphase inversion temperature improve the membrane porosity up to 64%. In addition, the FESEM images explained that membrane morphology obviously change with the effect of temperature during phase inversion process.
Authors: Xue Wu Liu, Yong Qiang Du, Jie Tang
Abstract: Microporous polyvinylidene fluoride (PVDF) membranes were prepared by supercritical CO2-induced phase inversion. The structure and morphology of prepared PVDF membranes were characterized by SEM. The effects of processing parameters such as CO2 pressure, temperature and PVDF concentration on the membrane morphologies, pore size distribution and especially on the porosity of the membranes were investigated. The results showed that when the PVDF concentration was between 15-35wt.%, the temperature and the pressure were respectively in the range of 35-60°Cand 8-16MPa, the prepared PVDF membrane showed a cellular structure; the porosity changed in the range of 55.2~85.7% and showed a peak valuewith the increase of temperature, CO2 pressure and PVDF concentration. The effects of process parameters on the membrane porosity were explained based on the properties of supercritical fluids.
Authors: Chun Li Yang, Wei Li, Shang Quan Zhang, Jian Jun Liu, Chu Sheng Chen, Wei Liu
Abstract: YSZ electrolyte-supported hollow-fiber SOFCs were successfully fabricated and their electrical and mechanical properties were investigated. The as-prepared hollow fiber SOFCs show a high mechanical strength of 149.0 MPa and 177.9 MPa before and after reduction by hydrogen gas, respectively. The open circuit voltage (OCV) values are greater than 1.0 V and the maximum power densities reach 146 mW cm-2 at 800°C, using wet H2 (~3% H2O) and static air as fuel and oxidant gas, respectively. As a result of high packing densities, this kind of YSZ electrolyte-supported hollow-fiber SOFCs has a high potential for practical applications.
Authors: Vanessa Nóbrega Medeiros, Thamyres Cardoso de Carvalho, Amanda Melissa Damião Leite, Edcleide Maria Araújo, Renê Anísio da Paz, Hélio Lucena Lira
Abstract: Polymeric membranes were produced from the nanocomposites of polyethersulfone and clay (untreated-MMT and treatment-OMMT), by phase inversion technique, in the proportions of 3 and 5% w/w, using as the solvent N, N dimethylformamide (DMF). From XRD results it was noted a change in the structure of the MMT by organophilization process with increase of the interplanar basal distance. To the membranes it was observed an exfoliated and/or partially exfoliated structure. From SEM images the nanocomposite membranes showed a surface apparently exempt of pores, however in the cross-section images shows an anisotropic structure, where the skin is dense and the porous support displays macrovoids. By the flow measurement, it was found that the compositions presented the same tendency in the flow lines, where the flow is high on the beginning and drops over time; and the inclusion of clay increases the flow, especially to the membranes with MMT 5%.
Authors: Elieber Barros Bezerra, A.M.D. Leite, E.M. Araújo, T.J.A. Melo, C.T. Cunha, Larissa Fernandes Maia
Abstract: Polymer blend is the name for the physical mixture of two or more polymers and/or copolymers, and this allows the obtention of new materials with superior properties to those of the pure components. The blends have been used in obtaining membranes in order to improve the barrier properties so that it can separate two phases totally or partially, restricting the transport of one or more chemical species. In this work, polymer membranes were obtained from blends of PA6/PPgAA and PA6/PP/PPgAA by phase inversion method and were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was observed through the diffractograms that there were no significant variations in the characteristic peaks of PA6, and through SEM, it was observed the formation of microporous asymmetric membranes, where they showed a surface with higher porosity to the binary and ternary blends and presented smallest pore diameter for binary blends.
Authors: Károly Dobrovszky, Ferenc Ronkay
Abstract: Blending polymers is an effective method to develop novel materials, tailoring the properties of the components. However, different morphology structures can be formed during the preparation, which could result in a wide diversity of mechanical and physical properties. The properties of polymer blends are most significantly influenced by the emerging range of phase inversion, which depends on the composition ratio and the viscosity ratio. In this paper various blends were prepared, utilizing polyethylene terephthalate (PET), polystyrene (PS) and two high density polyethylenes (HDPE), which differ in flowability. After preliminary homogenization by twin screw extruder, standard injection moulded specimen were prepared in order to present the effects of phase inversion on tensile properties, shrinkage and burning characteristics in binary polymer blends.
Authors: Xiao Zhen Zhang, Yong Qing Wang, Jing Zhang, Qi Bing Chang, Yu Hua Jiang, Jian Er Zhou
Abstract: A cobalt-free perovskite oxide Ba0.5Sr0.5Fe0.8Cu0.2O3−δ (BSFCu) is applied as the cathode material for intermediate temperature micro-tubular solid oxide fuel cells (SOFCs) with asymmetric structure anode. The NiO-YSZ hollow fiber anode as support was prepared by the phase inversion technique. The as-prepared fiber anode shows a special asymmetric structure consisting of porous sponge-like structure in the middle and finger-like porous structure on the inner and outer side. Dense thin YSZ electrolyte membrane and SDC transition layer were deposited on the NiO-YSZ hollow fiber anode by a vacuum-assisted dip-coating and co-sintering technique. Laboratory-sized micro-tubular single cells of NiO-YSZ/YSZ+SDC/BSFCu-SDC were tested at 650-750°C with humidified H2 as the fuel and static ambient air as the oxidant. The peak power densities of 437.2, 326.5 and 214.4 mWcm-2 can be obtained at 750, 700 and 650°C, respectively. The experimental results indicate that the cobalt-free perovskite oxide BSFCu is a promising cathode material candidate for the developed intermediate temperature micro-tubular SOFC with asymmetric hollow fiber anode.
Authors: Samaneh Shahgaldi, Zahira Yaakob, Mostafa Ghasemi, Wan Ramli Wan Daud, Dariush Jafar Khadem
Abstract: One dimensional (1D) nanostructure materials such as nanowires, nanofibers, and nanorods with porous structures have potential for use in various applications. Electrospinning is one of the versatile techniques with the ability of producing cost-effective, large production, highly porous nanofibers and membrane with large surface to volume ratios. Poly ether sulfone (PES) is a kind of special engineering plastic with good processing characteristics. In this paper, synthesis of PES membrane was investigated by two main methods, i.e. phase inversion and electrospiing. For electrospining, the main effective parameters such as concentration of polymer and solvent, for finding the optimized condition of electrospun PES membrane was studied. The produced membranes were characterized by SEM for morphology and BET observation of surface area, permeability, flux, and mechanical propertise for different applications.
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