Разработка и тестирование высокопористых анодов твердооксидных топливных элементов микротрубчатого типа

In this paper, to study the influence of geometric size on the swell of extrusion forming of plastic micro-pipe, we performed the numerical simulation based on the finite element software Polyflow. The geometric models of plastic micro-pipes with different inner diameters but same wall thickness were established. Under the same boundary conditions and material parameters, the extrusion forming and swell ratios of plastic micro-pipes with different sizes were obtained. At the same time, the numerical results of traditional extrusion forming were compared with that of the gas-assisted extrusion forming. Numerical results show that the swell ratio of outer diameter and wall thickness increase with the decreasing of the geometric size for the traditional extrusion, but the extrudate swell of plastic micro-pipe is well eliminated by using the gas-assisted method.

Study of gas separation properties of ethylene vinyl acetate (EVA) copolymer membranes prepared via phase inversion method

Influence of quench medium on the structures and gas permeation properties of polysulfone membranes made by wet and dry/wet phase inversion

Effects of Pluronic F127 on phase inversion and membrane formation of PAN hollow fibers for air filtration

In this study, the effect of wall thickness on the extrudate swell of plastic microtubules was investigated by using the finite element numerical method. For the traditional extrusion and gas-assisted extrusion, under the same process parameters, the extrudate swell ratios of plastic microtubules with the different wall thicknesses were all obtained. Moreover, to analyze the difference between the traditional extrusion and gas-assisted extrusion, the physical fields distributions, such as flow velocities, pressure and the stresses distributions of plastic microtubules with the different wall thicknesses under two kinds different extrusions were also obtained and compared. Numerical results show that, for the traditional extrusion, the extrudate swell ratio decreases with the increasing of the wall thickness, but for the gas-assisted extrusion, the swell ratios are equal to 0 and not changed. In addition, from the viewpoints of physical fields distributions, for the traditional extrusion, with the increasing of the wall thickness, the velocities, pressure and stresses of melt are all decreased, which result in the reducing of the extrudate swell phenomenon. However, for the gas-assisted extrusion, the X velocity, pressure, and stresses are all equal to 0, which results in the elimination the extrudate swell phenomenon of plastic microtubules.

The effect of the second phase inversion on microstructures in phase inversion EVAL membranes

The incorporation of inorganic nanomaterials into polymer matrix can result a wide range of property enhancement. Hence, mixed matrix membranes composed of polymeric thin film and well-dispersed nanoparticles have been extensively studied in CO2 separation. In this work, polyhedral oligomeric silsesquioxanes (POSS) with amino functionality was incorporated into polysulfone (PSf) membrane. After phase inversion, PSf/POSS membrane was impregnated with the gas selective ionic liquid (IL), [emim][TF2N] to enhance CO2 separation. was further used to modify the membrane after the phase inversion process. The membranes were characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM) with energy dispersive X-ray analysis (EDX). The SEM images showed that the POSS particles were well distributed on the membrane surface without interfacial defects due to their compatibility with the polymer. However, the large nanocage structure of POSS allow gas permeation without much selectivity. After incorporating IL as proven in EDX results, PSf/POSS-IL exhibited an increment about 454 % and 430 % in CO2 permeance and CO2/N2 selectivity, respectively.

In this study, a series of nonsolvents including ethyl acetate (EAC), acetic acid (HAC), n‐butyl alcohol (NBA), iso‐propyl alcohol (IPA) and ethanol (EA) were selected during the phase inversion process of poly(arylene ether nitrile) (PEN) films. The mechanism of film formation was tightly related with the interactions among polymer, solvent and nonsolvent. In the case of EAC, the aggregated sphere in P‐EAC confirmed the in situ aggregate mechanism of polymer chains during the phase inversion process. As the nonsolvent‐polymer interaction increases from HAC, NBA, IPA to EA, the phase inversion mechanism was gradually changed from the delayed to transient, as verified by the morphology transformation from spongy‐like to finger‐like. Dielectric, mechanical properties of these PEN films are tightly related with the morphological features, while their thermal properties are similar. Among them, P‐EAC show the optimal properties for potential application in the low‐k films, with a dielectric constant, Td5%, tensile strength of 1.99, 515.84°C, and 36.08 MPa, respectively. This work can provide references for tailoring the structures and properties of PEN films through rational selection of nonsolvent via the phase inversion method.

Tiny water droplets in oil emulsions are commonly encountered in the petroleum industry. The high viscosity of the oil hampers the physical separation of the water droplets from the oil.1 Phase inversion could be a potential workaround for this problem by making water, a much less viscous phase, the continuous medium. In the present work, we focused on triggering phase inversion of a solid‐stabilized emulsion. We induced a catastrophic phase inversion by the continuous addition of a dispersed phase. The evolution of droplet morphology during the phase inversion process was observed and was measured in‐line using a particle vision microscope, which proved to be a powerful tool for monitoring this rapid, unstable process. A linear relationship between the droplet size and the dispersed phase volume fraction before the phase inversion was observed, indicating that a higher dispersed phase volume fraction was needed for the phase inversion to occur with higher particle concentrations. The phase inversion conditions were applied in a regime where the particles were insufficient to fully cover the interface. Our findings indicated that the number of particles per surface area appears to be a crucial parameter in triggering phase inversion, regardless of the particle concentration. The phase inversion mechanism of our solid‐stabilized emulsion can be explained by the relationship between the initial particle coverage of the interface and the coalescence rate of the system.

A defect‐free polyether sulfone (PES) asymmetric membrane was prepared by a one‐step phase inversion process and applied gas separation process in this article. The morphology of the PES asymmetric membrane formed via phase inversion that was correlated with the solvent composition, evaporation environment, coagulation bath, and so forth. The results reveal two kinds of coagulation phenomena that lead to different membrane structures and separation results. An instantaneous coagulation PES membrane formed a finger‐like structure within the membrane, and a delayed coagulation PES membrane resulted in a sponge‐like structure membrane. The selectivity of O2/N2 for membrane gas separation indicated that the asymmetric membranes prepared via a one‐step process in this study were defect‐free. Using the phase inversion method to fabricate asymmetric membranes improved the low permeability characteristic of glassy polymers. The maximum permeability of CO2 for the PES asymmetric membrane in the text can approach 30 Barrer. The results of gas separation for the sponge‐like PES membrane showed that the selectivity of O2/N2 and CO2/N2 was 7.1 and 35.6, respectively. This research showed that a PES asymmetric membrane was fabricated via a one‐step process without further defect repair and was applied effectively for CO2 membrane gas separation.

Chapter 3 - Formation of Flat Sheet Phase Inversion MD Membranes

Experimental investigation of phase inversion in a stirred vessel using LIF

The effects of fluorocarbon special surfactant (FS-30) additive on the phase inversion, morphology and separation performance of poly(vinylidene fluoride) (PVDF) membranes

Waterborne dispersions of bisphenol A epoxy resin were prepared by the so-called phase-inversion emulsification technique. The electrical properties, rheological behavior and morphological evolution during the phase inversion process were characterized systematically. It was shown that both emulsifier concentration and emulsification temperature play great roles in controlling the phase inversion process as well as the structural features of the waterborne particles. A high emulsifier concentration, i.e. 10.90 wt% and a low emulsification temperature, i.e. 73 °C, facilitate complete phase inversion, in which all water droplets in the system are simultaneously transformed into the continuous phase at the phase-inversion point (PIP). In this case, sub-micron-sized, discrete waterborne particles were formed. In contrast, a complex water-in-oil-in-water structure was achieved by incomplete phase inversion at a low emulsifier concentration, i.e. 2.33 wt%, and a high temperature of 80 °C. The morphological evolution observed by scanning electron microscopy revealed that not all the water droplets in the system were converted into the continuous phase at the PIP and that some small water drops were trapped within the waterborne structure.

Spherical polyimide (PMDA-ODA) shells with high aspect ratio (OD = 900 to 1020 μm and wall thickness = 0.7 to 8.0 μm) were successfully fabricated by the vapor deposition method. These shells were characterized in terms of gas permeability, Young’s modulus, tensile strength, and ultimate elongation. The measured properties of the shells agreed with those of commercial films (Kapton®). Post-coating treatments of the shells, including thermal imidization in air and biaxial expansion, effectively increased gas permeability. Air-curing resulted in shells that were more brittle and twice as permeable as those cured in nitrogen. Since no difference in chemical composition was found between the N2- and air-cured shells, the effect of air-curing may be attributed to morphological or microstructural changes due to oxygen or water vapor in air. Shells that were expanded plastically showed over 300-fold increase in gas permeability, while retaining half of the original Young’s modulus. The effect of expansion on permeability may have arisen from localized plastic deformation. Both treatments will be useful for preparing ICF targets that allow a rapid fill with DT fuel for cryogenic experiments.