Poly(m-phenylene isophthalamide)(PMIA),a key aromatic polyamide,is widely used for its outstanding mechanical strength,high thermal stability,and excellent insulation properties.However,different applications demand v...Poly(m-phenylene isophthalamide)(PMIA),a key aromatic polyamide,is widely used for its outstanding mechanical strength,high thermal stability,and excellent insulation properties.However,different applications demand varying dielectric properties,so tailoring its dielectric per-formance is essential.PMIA was first synthesized in this study,followed by introducing pores and developing porous PMIA films and PMIA-based composites with reduced dielectric constants.Porous PMIA films were fabricated using the wet phase inversion process with N,N-dimethylac-etamide(DMAC)solvent and water as the non-solvent.The impact of casting solution composi-tion and coagulation bath temperature on pore structures was analyzed.A film produced with 18%PMIA and 5%LiCl in a 35℃coagulation bath achieved the lowest dielectric constant of 1.76 at 1 Hz,48%lower than the standard PMIA film,which had a tensile strength of 18.5 MPa and an initial degradation temperature of 320℃.展开更多
In this review, our recent work in phase inversion emulsification （PIE） for polymer （especially epoxy resin） waterborne dispersions is summarized. Based on experimental results about PIE process, the physical mode...In this review, our recent work in phase inversion emulsification （PIE） for polymer （especially epoxy resin） waterborne dispersions is summarized. Based on experimental results about PIE process, the physical model is proposed which can guide the synthesis of the waterborne dispersions such as polymer/nanoparticle composite dispersion. In the presence of a latent curing catalyst, PIE can give a crosslinkable epoxy resin waterborne dispersion. The dispersions can form cured transparent coatings with some unique properties such as UV shielding. They are promising in functional coatings, waterborne resin matrices for composites, and sizing for high performance fibers.展开更多
In this work,a sponge-like polysulfonamide(PSA)/SiO_2 composite membrane is unprecedentedly prepared by the phase inversion method,and successfully demonstrated as a novel separator of lithium-ion batteries(LIBs).Comp...In this work,a sponge-like polysulfonamide(PSA)/SiO_2 composite membrane is unprecedentedly prepared by the phase inversion method,and successfully demonstrated as a novel separator of lithium-ion batteries(LIBs).Compared to the commercial polypropylene(PP) separator,the sponge-like PSA/SiO_2 composite possesses better physical and electrochemical properties,such as higher porosity,ionic conductivity,thermal stability and flame retarding ability.The LiCoO_2/Li half-cells using the sponge-like composite separator demonstrate superior rate capability and cyclability over those using the commercial PP separator.Moreover,the sponge-like composite separator can ensure the normal operation of LiCoO_2/Li half-cell at an extremely high temperature of 90 °C,while the commercial PP separator cannot.All these encouraging results suggest that this phase inversion based sponge-like PSA/SiO_2 composite separator is really a promising separator for high performance LIBs.展开更多
Waterborne ultrafine particles of epoxy resin were prepared by phase inversion technique. The results of SEM revealed that the particles diameter was in the range of 50 to 100 nm and the effects on amount of water req...Waterborne ultrafine particles of epoxy resin were prepared by phase inversion technique. The results of SEM revealed that the particles diameter was in the range of 50 to 100 nm and the effects on amount of water required at phase inversion point were also discussed.展开更多
The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterborne dispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne...The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterborne dispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne dispersions by PIET in our laboratory were summarized. Electrical properties, rheological behavior and morphological evolution during phase inversion progress were systematically characterized. The effects of the emulsifier concentration and emulsification temperature on phase inversion progress and the structural features of the waterborne particles were studied as well. The deformation and break up of water drops in a shear field were analyzed in terms of micro-theology, while the interaction and coalescence dynamics of water drops were discussed in terms of DLVO theory and Smoluchowski effective collision theory, respectively. Based on the experimental results and theoretical analysis, a physical model of phase inversion progress was suggested, by which the effects of the parameters on phase inversion progress and the structural features of the waterborne particles were interpreted and predicted.展开更多
The mechanism of phase inversion emulsification process （PIE） was studied for waterborne dispersion of highly viscous epoxy resin using non-ionic polymeric surfactants. Drop deformation and breakup, rheological prop...The mechanism of phase inversion emulsification process （PIE） was studied for waterborne dispersion of highly viscous epoxy resin using non-ionic polymeric surfactants. Drop deformation and breakup, rheological properties, conductivity, and particle size measurements reveal the micro-structural transition amid emulsification. It is revealed that strong flow causes water drop to burst with the formation of droplets and huge interface. Phase inversion corresponds to an abrupt rheological transition from a type of viscous melt with weak elasticity to a highly elastic type of aqueous gel. This implies that the phase inversion equivalent to a curvature inversion. Based on this, a geometric model is postulated to correlate process variables to the particle size. The coverage and conformation of the surfactant plays key role for the particle size of the final emulsion. The interactions of thermodynamic and hydrodynamic effects are also discussed. It is concluded that the thermodynamics control the PIE while the hydrodynamics drives the creation of interface and involves every step of PIE.展开更多
In this work, new composite membranes were successfully prepared via phase inversion technique using polyvinyl chloride(PVC) and polyvinylpyrrolidone(PVP) as polymers and tetrahydrofuran(THF) and N-methyl-2-pyrrolidon...In this work, new composite membranes were successfully prepared via phase inversion technique using polyvinyl chloride(PVC) and polyvinylpyrrolidone(PVP) as polymers and tetrahydrofuran(THF) and N-methyl-2-pyrrolidone(NMP) as solvents. The prepared membranes have been characterized by scanning electron microscope(SEM), and fourier transforms infrared spectroscopy(FTIR). The scanning electron microscope results prove that the prepared membranes are smooth and their pores are distributed throughout the whole surface and bulk body of the membrane without any visible cracks. The stress–strain mechanical test showed an excellent mechanical behavior enhanced by the presence of PVP in the prepared membranes. The membranes performance results showed that the salt rejection reached 98% with a high flux. This, in turn, makes the prepared membranes can be applied for sea and brackish water treatment through membrane distillation technology.展开更多
One process based on phase inversion of fillers in microstructures for the fabrication of multi-level three-dimensional(3-D) microstructures is described using SU-8, a kind of epoxy photoresist, as the model construct...One process based on phase inversion of fillers in microstructures for the fabrication of multi-level three-dimensional(3-D) microstructures is described using SU-8, a kind of epoxy photoresist, as the model constructing materials. This process is depicted by use of the routine photolithography technique to construct the top layer of 3-D microstructures on the bottom layer of 3-D microstructures layer by layer. This process makes it possible to fabricate multi-level 3-D microstructures with connectors at desired locations, and to seal long span microstructures(e.g. very shallow channels with depth less than 50 μm and width more than 300 μm) without blockage. In addition, this process can provide a sealing layer by the solidification of a liquid polymer layer, which can be as strong as the bulk constructing materials for microstructures due to a complete contact and cross-linking between the sealing layer and the patterned layers. The hydrodynamic testing indicates that this kind of sealing and interconnection can endure a static pressure of more than 10 MPa overnight and a hydrodynamic pressure drop of about 5.3 MPa for more than 8 hours by pumping the tetrahydrofuran solution through a 60 μm wide micro-channels.展开更多
Adding Al is an important strategy to obtain ultrahigh specific strength in BCC refractory high-entropy alloys(RHEAs).However,the main structure typically transitions from disordered BCC to ordered B2 with increasing ...Adding Al is an important strategy to obtain ultrahigh specific strength in BCC refractory high-entropy alloys(RHEAs).However,the main structure typically transitions from disordered BCC to ordered B2 with increasing Al concentration,leading to poor ductility.In the present study,a phase inversion in a high-Al-content B2-RHEA(Zr_(40)Ti_(28)Nb_(12)Al_(20))was systematically studied through thermo-mechanical treatment.The grains of the single B2 phase transformed inversely to the BCC+B2 microstructure with a dispersion of spherical B2 precipitates in the BCC grains.The evolution of the microstructure began with the decomposition of the B2 phase into Al-rich and Al-poor regions.The subsequent coarsening of the Al-rich B2 precipitates continuously consumes Al and Zr atoms from the solution.The depletion of Al and Zr in the matrix drives it to gradually form the disordered BCC structure and eventually transform to a single BCC phase matrix.This phase inversion enhanced tensile ductility of the RHEA while still maintaining its high specific strength.The current study provides a novel idea for inhibiting Al-induced brittleness of RHEAs at high Al content.展开更多
Phase inversion emulsification technique is a recently developed method to achieve waterborne dispersions of polymer resin. It is found that the electrical and rheological properties of the system experience abrupt ch...Phase inversion emulsification technique is a recently developed method to achieve waterborne dispersions of polymer resin. It is found that the electrical and rheological properties of the system experience abrupt changes in the vicinity of the phase inversion point (PIP). Before PIP, the system is a Newtonian fluid. At PIP, the continuous phase transforms from polymer resin to water phase with the result that the electrical resistance of the system drops abruptly. Meanwhile, the system at PIP exhibits high viscoelasticity originated from the formation of a physical gel alike structure among the waterborne particles. Besides, the morphology evolution is observed by Scanning Electron Microscopy (SEM).展开更多
Microporous asymmetric polystyrene （PS） membranes were prepared by supercritical CO2-induced phase inversion. The effects of different process parameters, such as temperature, COe pressure and PS concentration in ca...Microporous asymmetric polystyrene （PS） membranes were prepared by supercritical CO2-induced phase inversion. The effects of different process parameters, such as temperature, COe pressure and PS concentration in casting solution, on the membrane morphologies, pore size distribution and especially on the porosity of the membranes were experimentally investigated. The porosity showed a tendency of increasing to a maximum and then decreasing with an increase of temperature, CO2 pressure or PS concentration. The effects of process parameters on the membrane porosity were explained based on the properties of supercritical fluids.展开更多
The demand for wearable electronics is still growing,and the rapid development of new electrochemical materials and manufacturing processes allows for innovative approaches to power these devices.Here,three-dimensiona...The demand for wearable electronics is still growing,and the rapid development of new electrochemical materials and manufacturing processes allows for innovative approaches to power these devices.Here,three-dimensional(3D)self-supported reduced graphene oxide/poly(3,4-ethylenedioxythiophene)(rGO/PEDOT)hybrid fiber fabrics are systematically designed and constructed via phase inversion-based microfluidic-fiber-spinning assembly(MFSA)method,followed by concentrated sulfuric acid treatment and chemical reduction.The rGO/PEDOT fiber fabrics demonstrate favorable flexibility,interconnected hierarchical network,large specific surface area,high charge storage capacity,and high electrical conductivity.In addition,the all-solid-state supercapacitor made of these rGO/PEDOT fiber fabrics proves large specific capacitance(1028.2 mF cm^(−2)),ultrahigh energy density(22.7μWh cm^(−2)),long-term cycling stability,and excellent flexibility(capacitance retention remains at 84%,after 5000 cycles of continuous deformation at 180o bending angles).Further considering those remarkable electrochemical properties,a wearable self-powered device with a sandwich-shaped supercapacitor(SC)is designed to impressively light up LEDs and power mini game console,suggesting its practical applications in flexible and portable smart electronics.展开更多
As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding...As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding scenarios.This paper discusses interferogram modeling and phase distortion cor-rection techniques for spaceborne DASH interferometers.The modeling of phase distortion interferograms with and without Doppler shift for limb observation was conducted,and the effectiveness of the analytical expression was verified through numerical simulation.The simulation results indicate that errors propagate layer by layer while using the onion-peeling inversion algorithm to handle phase-distorted interferograms.In contrast,the phase distortion correction algorithm can achieve effective correction.This phase correction method can be successfully applied to correct phase distortions in the interferograms of the spaceborne DASH interferometer,providing a feasible solution to enhance its measurement accuracy.展开更多
Experiments of phase inversion characteristics for horizontal oil-water two-phase flow in a stainless steel pipe loop （25.7 mm inner diameter,52 m long） are conducted. A new viewpoint is brought forward about the pr...Experiments of phase inversion characteristics for horizontal oil-water two-phase flow in a stainless steel pipe loop （25.7 mm inner diameter,52 m long） are conducted. A new viewpoint is brought forward about the process of phase inversion in oil-water two-phase pipe flow. Using the relations between the total free energies of the pre-inversion and post-inversion dispersions, a model for predicting phase inversion in oil-water two-phase pipe flow has been developed that considers the characteristics of pipe flow. This model is compared against other models with relevant data of phase inversion in oil-water two-phase pipe flow. Results indicate that this model is better than other models in terms of calculation precision and applicability. The model is useful for guiding the design for optimal performance and safety in the operation of oil-water two-phase pipe flow in oil fields.展开更多
A new ultrasound contrast imaging technique was proposed for eliminating the harmonic components from the emission signal transmitted by the broadband ultrasonic system.Reversal phase-inversion pulse was used for the ...A new ultrasound contrast imaging technique was proposed for eliminating the harmonic components from the emission signal transmitted by the broadband ultrasonic system.Reversal phase-inversion pulse was used for the first time to separate the contrast harmonics from the harmonics in the emission signal to improve the detection of contrast micro-bubbles.Based on the nonlinear acoustic theory of finite-amplitude effects and the associated distortion of the propagating wave,the Bessel-Fubini series model was applied to describe the nonlinear propagation effects of the reversal phase-inversion pulse,and the Church's equation for zero-thickness encapsulation model was used to produce the scattering-pulse of the bubble.For harmonic imaging,the experiment was performed using a 64-element linear array,which was simulated by Field II.The results show that the harmonic components from the emission signal can be completely cancelled,and the harmonics generated by the nonlinear propagation of the wave through the tissue,can be reduced by 15-30 dB.Compared with the short pulse,the reversal phase-inversion pulse can improve the contrast and definition of the harmonic image significantly.展开更多
A delay time was observed for both W/O inversion to O/W and the opposite inversion process. The delay time decreased with increasing stirring speed. For O/W inversion to W/O, the delay time was very sensitive to the o...A delay time was observed for both W/O inversion to O/W and the opposite inversion process. The delay time decreased with increasing stirring speed. For O/W inversion to W/O, the delay time was very sensitive to the oil volume fraction and the initial stirring speed. Increased oil volume fraction and increased initial stirring speed both reduced the delay time. Inversion from W/O to O/W was a gradual process. But inversion from O/W to W/O had two stages: the preparation stage and the phase inversion stage. The time needed in the first stage was the delay time.展开更多
In this paper we report results from on-going theoretical and experimental studies carried out jointly at Imperial College London and University College London. Laser-induced fluorescence （LIF） is used to investigat...In this paper we report results from on-going theoretical and experimental studies carried out jointly at Imperial College London and University College London. Laser-induced fluorescence （LIF） is used to investigate liquid-liquid phase inversion experimentally and to observe in detail phenomena that accompany the inversion process, such as secondary dispersions and drop coalescence and breakup. Theoretically, a two-region model together with a criterion based on a dynamic balance between drop coalescence and breakup is employed to predict phase inversion. The concept of a radial distribution function for hard spheres was also utilized in order to better model the interaction of drops at high dispersed phase holdup, The modeling work is capable of predicting the existence of ambivalent ranges which are in good agreement with experimental observations.展开更多
This study investigated the effect of poly(ethylene glycol)(PEG)additive as a pore-former on the structure formation of membranes and their permeation properties connected with the changes in thermodynamic and kinetic...This study investigated the effect of poly(ethylene glycol)(PEG)additive as a pore-former on the structure formation of membranes and their permeation properties connected with the changes in thermodynamic and kinetic properties in the phase inversion process.The membranes were prepared by using polyetherimide/Nmethyl-2-pyrrolidone/PEG(PEI/NMP/PEG)casting solution and water coagulant.The resulting membranes,prepared by changing the ratio of PEG to PEI,were characterized by scanning electron microscope(SEM)observations,measurements of water flux andγ-globin rejection.The thermodynamic and kinetic properties of the membrane-forming system were studied through viscosity.The pore radius distribution curves were especially obtained by differential scanning calorimetry(DSC).Furthermore,the membranes were characterized for pure water flux and rejection of solute and by SEM observation.The filtration results agreed well with the SEM observations.As expected,PEG with a fixed molecular weight(PEG 600)acted as a pore forming agent,and membrane porosity increased as the PEG content of the casting solution increased.展开更多
This study proposes a novel and sustainable method for fabricating 3D-printed carbon-based electrodes for electrochemical wastewater treatment.We prepared B,N-doped carbon electrodes with hierarchical porosity and a s...This study proposes a novel and sustainable method for fabricating 3D-printed carbon-based electrodes for electrochemical wastewater treatment.We prepared B,N-doped carbon electrodes with hierarchical porosity and a significantly enhanced surface area-to-volume ratio(up to 180%)compared to non-optimized analogues using a synergistic combination of 3D printing,phase inversion,and microwave plasma-enhanced chemical vapor deposition.This process allows the metal-free growth of vertically aligned carbon nanostructures directly onto polymer-derived substrates,resulting in a 20-fold increase in the electrochemically active surface area.Computational fluid dynamics simulations were used to improve mass transport and reduce pressure drop.Electrochemical characterization demonstrated that the optimized electrodes performed significantly better,achieving 4.7-,4-,and 6.5-fold increases in the degradation rates of atenolol,metoprolol,and propranolol,respectively,during electrochemical oxidation.These results highlight the efficacy of the integrated fabrication and simulation approach in producing high-performance electrodes for sustainable wastewater treatment applications.展开更多
Experiments were carried out to investigate the influences of cation from electrolytes and acidity/alkalinity on the phase behavior of sodium dodecyl sulfate-n-butanol-organics-water （with electrolytes） microemulsio...Experiments were carried out to investigate the influences of cation from electrolytes and acidity/alkalinity on the phase behavior of sodium dodecyl sulfate-n-butanol-organics-water （with electrolytes） microemulsion sys-tem. The organics used is commercial kerosene. The volume ratio of water to organics is 1︰1. The results show that the type and valence of electrolyte cations are important factors influencing the microemulsion behavior. Biva-lent Ca2＋is more effective than monovalent K＋and Na＋for the formation of Winsor type III and II microemulsion. For electrolytes with the same monovalent cation Na＋, i.e. NaCl and Na2CO3, anions in the electrolyte have some effect. Bivalent anion 23CO - leads to a lower activity of cation Na＋than monovalent anion Cl-. NaOH （or KOH） behaves similar with NaCl （or KCl）. When HCl is used as electrolyte, its acidity plays an important role. Phase in-version of microemulsion from type III （or II） to type I is observed through precipitation of Ca2＋using Na2CO3, neutralization of HCl by NaOH, and addition of water to the system, which releases the oil from the microemulsion.展开更多
文摘Poly(m-phenylene isophthalamide)(PMIA),a key aromatic polyamide,is widely used for its outstanding mechanical strength,high thermal stability,and excellent insulation properties.However,different applications demand varying dielectric properties,so tailoring its dielectric per-formance is essential.PMIA was first synthesized in this study,followed by introducing pores and developing porous PMIA films and PMIA-based composites with reduced dielectric constants.Porous PMIA films were fabricated using the wet phase inversion process with N,N-dimethylac-etamide(DMAC)solvent and water as the non-solvent.The impact of casting solution composi-tion and coagulation bath temperature on pore structures was analyzed.A film produced with 18%PMIA and 5%LiCl in a 35℃coagulation bath achieved the lowest dielectric constant of 1.76 at 1 Hz,48%lower than the standard PMIA film,which had a tensile strength of 18.5 MPa and an initial degradation temperature of 320℃.
基金This project is supported by NSF of China(Nos. 20104008 and 29774038)State Key Laboratory of Polymer Physics and Chemistry.
文摘In this review, our recent work in phase inversion emulsification （PIE） for polymer （especially epoxy resin） waterborne dispersions is summarized. Based on experimental results about PIE process, the physical model is proposed which can guide the synthesis of the waterborne dispersions such as polymer/nanoparticle composite dispersion. In the presence of a latent curing catalyst, PIE can give a crosslinkable epoxy resin waterborne dispersion. The dispersions can form cured transparent coatings with some unique properties such as UV shielding. They are promising in functional coatings, waterborne resin matrices for composites, and sizing for high performance fibers.
基金Supported by the funding from "135" Projects Fund of CAS-QIBEBT Director Innovation FoundationThink-Tank Mutual Fund of Qingdao Energy Storage Industry Scientific Research+3 种基金Qingdao Key Lab of Solar Energy Utilization and Energy Storage Technologythe Strategic Priority Research Program of the Chinese Academy of Sciences(XDA09010105)National Natural Science Foundation of China(51502319)Shandong Provincial Natural Science Foundation(ZR2016BQ18)
文摘In this work,a sponge-like polysulfonamide(PSA)/SiO_2 composite membrane is unprecedentedly prepared by the phase inversion method,and successfully demonstrated as a novel separator of lithium-ion batteries(LIBs).Compared to the commercial polypropylene(PP) separator,the sponge-like PSA/SiO_2 composite possesses better physical and electrochemical properties,such as higher porosity,ionic conductivity,thermal stability and flame retarding ability.The LiCoO_2/Li half-cells using the sponge-like composite separator demonstrate superior rate capability and cyclability over those using the commercial PP separator.Moreover,the sponge-like composite separator can ensure the normal operation of LiCoO_2/Li half-cell at an extremely high temperature of 90 °C,while the commercial PP separator cannot.All these encouraging results suggest that this phase inversion based sponge-like PSA/SiO_2 composite separator is really a promising separator for high performance LIBs.
基金This project is supported by the Scientific Fund of Polymer Physics Laboratory,Institute of Chemistry,Chinese Academy of Sciences.
文摘Waterborne ultrafine particles of epoxy resin were prepared by phase inversion technique. The results of SEM revealed that the particles diameter was in the range of 50 to 100 nm and the effects on amount of water required at phase inversion point were also discussed.
基金This work was supported by the National Key Project for Fundamental Research, "Macromolecular Condensed State" of Ministry of Science and Technology of China and National Natural Science Foundation of China 29774038.
文摘The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterborne dispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne dispersions by PIET in our laboratory were summarized. Electrical properties, rheological behavior and morphological evolution during phase inversion progress were systematically characterized. The effects of the emulsifier concentration and emulsification temperature on phase inversion progress and the structural features of the waterborne particles were studied as well. The deformation and break up of water drops in a shear field were analyzed in terms of micro-theology, while the interaction and coalescence dynamics of water drops were discussed in terms of DLVO theory and Smoluchowski effective collision theory, respectively. Based on the experimental results and theoretical analysis, a physical model of phase inversion progress was suggested, by which the effects of the parameters on phase inversion progress and the structural features of the waterborne particles were interpreted and predicted.
基金This project was supported by the National Natural Science Foundation of China (No. 20490220)Major State Basic Research Projects (No. 2003CB615604), Shengli Oilfield, SINOPEC.
文摘The mechanism of phase inversion emulsification process （PIE） was studied for waterborne dispersion of highly viscous epoxy resin using non-ionic polymeric surfactants. Drop deformation and breakup, rheological properties, conductivity, and particle size measurements reveal the micro-structural transition amid emulsification. It is revealed that strong flow causes water drop to burst with the formation of droplets and huge interface. Phase inversion corresponds to an abrupt rheological transition from a type of viscous melt with weak elasticity to a highly elastic type of aqueous gel. This implies that the phase inversion equivalent to a curvature inversion. Based on this, a geometric model is postulated to correlate process variables to the particle size. The coverage and conformation of the surfactant plays key role for the particle size of the final emulsion. The interactions of thermodynamic and hydrodynamic effects are also discussed. It is concluded that the thermodynamics control the PIE while the hydrodynamics drives the creation of interface and involves every step of PIE.
文摘In this work, new composite membranes were successfully prepared via phase inversion technique using polyvinyl chloride(PVC) and polyvinylpyrrolidone(PVP) as polymers and tetrahydrofuran(THF) and N-methyl-2-pyrrolidone(NMP) as solvents. The prepared membranes have been characterized by scanning electron microscope(SEM), and fourier transforms infrared spectroscopy(FTIR). The scanning electron microscope results prove that the prepared membranes are smooth and their pores are distributed throughout the whole surface and bulk body of the membrane without any visible cracks. The stress–strain mechanical test showed an excellent mechanical behavior enhanced by the presence of PVP in the prepared membranes. The membranes performance results showed that the salt rejection reached 98% with a high flux. This, in turn, makes the prepared membranes can be applied for sea and brackish water treatment through membrane distillation technology.
基金financially supported by the National Science Foundation of China(No.50971010)New Teacher Foundation of Beihang University(211109)+1 种基金New Teacher Funds of Education Ministry of China(2008-00061025)SRF and SEM funds of Education Ministry of China
文摘One process based on phase inversion of fillers in microstructures for the fabrication of multi-level three-dimensional(3-D) microstructures is described using SU-8, a kind of epoxy photoresist, as the model constructing materials. This process is depicted by use of the routine photolithography technique to construct the top layer of 3-D microstructures on the bottom layer of 3-D microstructures layer by layer. This process makes it possible to fabricate multi-level 3-D microstructures with connectors at desired locations, and to seal long span microstructures(e.g. very shallow channels with depth less than 50 μm and width more than 300 μm) without blockage. In addition, this process can provide a sealing layer by the solidification of a liquid polymer layer, which can be as strong as the bulk constructing materials for microstructures due to a complete contact and cross-linking between the sealing layer and the patterned layers. The hydrodynamic testing indicates that this kind of sealing and interconnection can endure a static pressure of more than 10 MPa overnight and a hydrodynamic pressure drop of about 5.3 MPa for more than 8 hours by pumping the tetrahydrofuran solution through a 60 μm wide micro-channels.
基金support from the National Key Research and Development Program of China (No.2017YFB0702003)the National Natural Science Foundation of China (No.51871217)+2 种基金Yong Zhang thanks the Guangdong Basic and Applied Basic Research Foundation (No.2019B1515120020)the State Key Laboratory for Advanced Metals and Materials in the University of Science and Technology Beijing (No.2020Z-08)the Funds for Creative Research Groups of China (No.51921001).
文摘Adding Al is an important strategy to obtain ultrahigh specific strength in BCC refractory high-entropy alloys(RHEAs).However,the main structure typically transitions from disordered BCC to ordered B2 with increasing Al concentration,leading to poor ductility.In the present study,a phase inversion in a high-Al-content B2-RHEA(Zr_(40)Ti_(28)Nb_(12)Al_(20))was systematically studied through thermo-mechanical treatment.The grains of the single B2 phase transformed inversely to the BCC+B2 microstructure with a dispersion of spherical B2 precipitates in the BCC grains.The evolution of the microstructure began with the decomposition of the B2 phase into Al-rich and Al-poor regions.The subsequent coarsening of the Al-rich B2 precipitates continuously consumes Al and Zr atoms from the solution.The depletion of Al and Zr in the matrix drives it to gradually form the disordered BCC structure and eventually transform to a single BCC phase matrix.This phase inversion enhanced tensile ductility of the RHEA while still maintaining its high specific strength.The current study provides a novel idea for inhibiting Al-induced brittleness of RHEAs at high Al content.
基金This project is supported by Polymer PhysicsLaboratory, Institute of Chemistry the Chinese Academy of Sciences
文摘Phase inversion emulsification technique is a recently developed method to achieve waterborne dispersions of polymer resin. It is found that the electrical and rheological properties of the system experience abrupt changes in the vicinity of the phase inversion point (PIP). Before PIP, the system is a Newtonian fluid. At PIP, the continuous phase transforms from polymer resin to water phase with the result that the electrical resistance of the system drops abruptly. Meanwhile, the system at PIP exhibits high viscoelasticity originated from the formation of a physical gel alike structure among the waterborne particles. Besides, the morphology evolution is observed by Scanning Electron Microscopy (SEM).
文摘Microporous asymmetric polystyrene （PS） membranes were prepared by supercritical CO2-induced phase inversion. The effects of different process parameters, such as temperature, COe pressure and PS concentration in casting solution, on the membrane morphologies, pore size distribution and especially on the porosity of the membranes were experimentally investigated. The porosity showed a tendency of increasing to a maximum and then decreasing with an increase of temperature, CO2 pressure or PS concentration. The effects of process parameters on the membrane porosity were explained based on the properties of supercritical fluids.
基金supported by National Natural Science Foundation of China(11572160,22278225).
文摘The demand for wearable electronics is still growing,and the rapid development of new electrochemical materials and manufacturing processes allows for innovative approaches to power these devices.Here,three-dimensional(3D)self-supported reduced graphene oxide/poly(3,4-ethylenedioxythiophene)(rGO/PEDOT)hybrid fiber fabrics are systematically designed and constructed via phase inversion-based microfluidic-fiber-spinning assembly(MFSA)method,followed by concentrated sulfuric acid treatment and chemical reduction.The rGO/PEDOT fiber fabrics demonstrate favorable flexibility,interconnected hierarchical network,large specific surface area,high charge storage capacity,and high electrical conductivity.In addition,the all-solid-state supercapacitor made of these rGO/PEDOT fiber fabrics proves large specific capacitance(1028.2 mF cm^(−2)),ultrahigh energy density(22.7μWh cm^(−2)),long-term cycling stability,and excellent flexibility(capacitance retention remains at 84%,after 5000 cycles of continuous deformation at 180o bending angles).Further considering those remarkable electrochemical properties,a wearable self-powered device with a sandwich-shaped supercapacitor(SC)is designed to impressively light up LEDs and power mini game console,suggesting its practical applications in flexible and portable smart electronics.
文摘As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding scenarios.This paper discusses interferogram modeling and phase distortion cor-rection techniques for spaceborne DASH interferometers.The modeling of phase distortion interferograms with and without Doppler shift for limb observation was conducted,and the effectiveness of the analytical expression was verified through numerical simulation.The simulation results indicate that errors propagate layer by layer while using the onion-peeling inversion algorithm to handle phase-distorted interferograms.In contrast,the phase distortion correction algorithm can achieve effective correction.This phase correction method can be successfully applied to correct phase distortions in the interferograms of the spaceborne DASH interferometer,providing a feasible solution to enhance its measurement accuracy.
基金Project supported by the National Natural Science Foundation of China (Grant No:50474061)
文摘Experiments of phase inversion characteristics for horizontal oil-water two-phase flow in a stainless steel pipe loop （25.7 mm inner diameter,52 m long） are conducted. A new viewpoint is brought forward about the process of phase inversion in oil-water two-phase pipe flow. Using the relations between the total free energies of the pre-inversion and post-inversion dispersions, a model for predicting phase inversion in oil-water two-phase pipe flow has been developed that considers the characteristics of pipe flow. This model is compared against other models with relevant data of phase inversion in oil-water two-phase pipe flow. Results indicate that this model is better than other models in terms of calculation precision and applicability. The model is useful for guiding the design for optimal performance and safety in the operation of oil-water two-phase pipe flow in oil fields.
基金Project(20070533131) supported by the National Research Foundation for the Doctoral Program of Higher Education of ChinaProject(50275150) supported by the National Natural Science Foundation of China
文摘A new ultrasound contrast imaging technique was proposed for eliminating the harmonic components from the emission signal transmitted by the broadband ultrasonic system.Reversal phase-inversion pulse was used for the first time to separate the contrast harmonics from the harmonics in the emission signal to improve the detection of contrast micro-bubbles.Based on the nonlinear acoustic theory of finite-amplitude effects and the associated distortion of the propagating wave,the Bessel-Fubini series model was applied to describe the nonlinear propagation effects of the reversal phase-inversion pulse,and the Church's equation for zero-thickness encapsulation model was used to produce the scattering-pulse of the bubble.For harmonic imaging,the experiment was performed using a 64-element linear array,which was simulated by Field II.The results show that the harmonic components from the emission signal can be completely cancelled,and the harmonics generated by the nonlinear propagation of the wave through the tissue,can be reduced by 15-30 dB.Compared with the short pulse,the reversal phase-inversion pulse can improve the contrast and definition of the harmonic image significantly.
基金the 34th International U NESCO Coursefor Advanced Research in Chemistry and Chem icalEngineeringand the National Natural
文摘A delay time was observed for both W/O inversion to O/W and the opposite inversion process. The delay time decreased with increasing stirring speed. For O/W inversion to W/O, the delay time was very sensitive to the oil volume fraction and the initial stirring speed. Increased oil volume fraction and increased initial stirring speed both reduced the delay time. Inversion from W/O to O/W was a gradual process. But inversion from O/W to W/O had two stages: the preparation stage and the phase inversion stage. The time needed in the first stage was the delay time.
基金Supported by the EPSRC (Nos. GR/R54699/01 and GR/R56044/01).
文摘In this paper we report results from on-going theoretical and experimental studies carried out jointly at Imperial College London and University College London. Laser-induced fluorescence （LIF） is used to investigate liquid-liquid phase inversion experimentally and to observe in detail phenomena that accompany the inversion process, such as secondary dispersions and drop coalescence and breakup. Theoretically, a two-region model together with a criterion based on a dynamic balance between drop coalescence and breakup is employed to predict phase inversion. The concept of a radial distribution function for hard spheres was also utilized in order to better model the interaction of drops at high dispersed phase holdup, The modeling work is capable of predicting the existence of ambivalent ranges which are in good agreement with experimental observations.
基金the financial support of the Major State Basic Research Program of China(2009CB623404)the National Natural Science Foundation of China(Grants No.20736003 and 20906056)+3 种基金the National High Technology Research and Development Program of China(2007AA06Z317,2008EG111021)the Foundation of Ministry of Education of China(20070003130)the Foundation of the State Key Laboratory of Chemical Engineering(SKL-ChE-08A01)the Postdoctor Science Foundation of China(023201069).
文摘This study investigated the effect of poly(ethylene glycol)(PEG)additive as a pore-former on the structure formation of membranes and their permeation properties connected with the changes in thermodynamic and kinetic properties in the phase inversion process.The membranes were prepared by using polyetherimide/Nmethyl-2-pyrrolidone/PEG(PEI/NMP/PEG)casting solution and water coagulant.The resulting membranes,prepared by changing the ratio of PEG to PEI,were characterized by scanning electron microscope(SEM)observations,measurements of water flux andγ-globin rejection.The thermodynamic and kinetic properties of the membrane-forming system were studied through viscosity.The pore radius distribution curves were especially obtained by differential scanning calorimetry(DSC).Furthermore,the membranes were characterized for pure water flux and rejection of solute and by SEM observation.The filtration results agreed well with the SEM observations.As expected,PEG with a fixed molecular weight(PEG 600)acted as a pore forming agent,and membrane porosity increased as the PEG content of the casting solution increased.
基金the National Science Centre,Poland,under the Agreement 2022/45/B/ST8/02847 is acknowledged(M.P.).
文摘This study proposes a novel and sustainable method for fabricating 3D-printed carbon-based electrodes for electrochemical wastewater treatment.We prepared B,N-doped carbon electrodes with hierarchical porosity and a significantly enhanced surface area-to-volume ratio(up to 180%)compared to non-optimized analogues using a synergistic combination of 3D printing,phase inversion,and microwave plasma-enhanced chemical vapor deposition.This process allows the metal-free growth of vertically aligned carbon nanostructures directly onto polymer-derived substrates,resulting in a 20-fold increase in the electrochemically active surface area.Computational fluid dynamics simulations were used to improve mass transport and reduce pressure drop.Electrochemical characterization demonstrated that the optimized electrodes performed significantly better,achieving 4.7-,4-,and 6.5-fold increases in the degradation rates of atenolol,metoprolol,and propranolol,respectively,during electrochemical oxidation.These results highlight the efficacy of the integrated fabrication and simulation approach in producing high-performance electrodes for sustainable wastewater treatment applications.
基金Supported by the National Natural Science Foundation of China(21106187)Promotive Research Funds for Excellent Young and Middle-aged Scientists of Shandong Province(BS2011NJ021)+1 种基金the Fundamental Research Funds for the Central Universities(11CX05016A)the Graduate Innovation Project of CUP 2012(CX-1214)
文摘Experiments were carried out to investigate the influences of cation from electrolytes and acidity/alkalinity on the phase behavior of sodium dodecyl sulfate-n-butanol-organics-water （with electrolytes） microemulsion sys-tem. The organics used is commercial kerosene. The volume ratio of water to organics is 1︰1. The results show that the type and valence of electrolyte cations are important factors influencing the microemulsion behavior. Biva-lent Ca2＋is more effective than monovalent K＋and Na＋for the formation of Winsor type III and II microemulsion. For electrolytes with the same monovalent cation Na＋, i.e. NaCl and Na2CO3, anions in the electrolyte have some effect. Bivalent anion 23CO - leads to a lower activity of cation Na＋than monovalent anion Cl-. NaOH （or KOH） behaves similar with NaCl （or KCl）. When HCl is used as electrolyte, its acidity plays an important role. Phase in-version of microemulsion from type III （or II） to type I is observed through precipitation of Ca2＋using Na2CO3, neutralization of HCl by NaOH, and addition of water to the system, which releases the oil from the microemulsion.
