72 results about "Membrane porosity" patented technology

The invention belongs to the technical field of porous ceramic materials and their preparation and especially discloses a pure silicon carbide filtering membrane and a preparation method thereof. The pure silicon carbide filtering membrane has a high porosity, a low pressure drop, high strength, good thermal shock resistance and a high use temperature. The preparation method can be realized easily and can guarantee product performances. The pure silicon carbide filtering membrane comprises pure SiC, is a surface membrane layer obtained by pile-up and binding of fine SiC particles and has aperture sizes of 0.1 to 20 microns and membrane porosity of 25 to 50%. Fine SiC particles, silicon powder, a pore-forming additive and one or more organic resins as raw materials are prepared into a surface membrane layer by spraying or dipping and the surface membrane layer is dried and sintered to form the pure silicon carbide filtering membrane. The pure silicon carbide filtering membrane can be used in an oxidation atmosphere and in a reducing atmosphere, has strong acid corrosion and alkaline corrosion resistance, and can be used for various high/low temperature fluid filtering purification fields such as coal gasification chemical engineering, integrated gasification combined cycle (IGCC) and pressurized fluidized bed combustion (PFBC) coal gasification power generation, and high temperature flue gas, automobile exhaust and water purification.

The invention discloses a high-strength polyimide nano fiber porous membrane. The porosity of the polyimide nano fiber porous membrane is 70-85%, the average pore diameter is 100-250 nm, the glass transition temperature is 260-400 DEG C, the tensile strength is 8-70 MPa, and the dimensional shrinkage after high-temperature 200 DEG C heat treatment for 1 hour is less than 0.3%. The chemical composition of the polyimide nano fiber porous membrane is copolymerized polyimide or blended polyimide. The invention also discloses a preparation method and application of the polyimide nano fiber porous membrane. The polyimide nano fibrous membrane disclosed by the invention is a membrane material having the advantages of high strength, low dimensional change rate, high porosity and favorable thermal properties.

The invention discloses a porous membrane and a pore-forming method of the porous membrane. According to a preparation method, a foaming pore-forming agent is introduced into a membrane-forming system and can generate uniformly distributed trace air bubbles through reaction so as to form a porous structure; therefore, the porosity of the membrane is improved, and macropore defects of the membrane can be avoided. The pore-forming method is applicable to membrane preparation by a solution method and a melting method. The pore-forming method specifically comprises the steps of (1) membrane preparation by the solution method: uniformly mixing a membrane-forming polymer and the foaming pore-forming agent, dissolving the mixture in a solvent to obtain a membrane casting solution containing the foaming pore-forming agent, wherein the membrane casting liquid enters an acidic coagulating bath after being subjected to scraping or is spun through a hollow fiber spinning head, so that the membrane casting liquid is solidified and formed to obtain the porous membrane when the foaming pore-forming agent reacts to form the air bubbles; (2) membrane preparation by the melting method: uniformly mixing the membrane-forming polymer and the foaming pore-forming agent, and obtaining an initial hollow fiber containing the foaming pore-forming agent through conventional hollow fiber membrane melting spinning, and putting the obtained initial hollow fiber into the acidic coagulating bath, wherein the hollow fiber is solidified and formed to obtain the porous membrane when the foaming pore-forming agent reacts to form the air bubbles.

The invention provides a type-C core-shell nanofiber membrane and an eccentric-shaft electrostatic spinning preparation method thereof.The preparation method is characterized by comprising the steps that a hydrophobic polymer is dissolved in a solvent to obtain a shell-layer solution; a hydrophilic polymer is dissolved in a solvent to obtain a core-layer solution, the shell-layer solution and the core-layer solution are respectively injected into an outer needle and an inner needle of an eccentric-shaft electrostatic spinning needle at a certain flowing speed, and meanwhile a high-voltage electrostatic generator is connected with the eccentric-shaft electrostatic spinning needle to perform electrostatic spinning so as to obtain the core-shell nanofiber membrane.The hydrophobic type-C grooved core-shell nanofibers obtained by means of the preparation method and used for membrane distillation can remarkably improve the defects of low membrane porosity, low heat conversion efficiency, low water vapor flux and membrane pore wetting of a traditional distillation membrane based on the particular structural characteristics, the porosity, heat conversion efficiency and water vapor flux of a common electrostatic spinning membrane can be improved, a membrane distillation technology can compete with a reverse osmosis technology in the field of seawater desalination.

Evaporative heat transfer system. The system includes a substrate and a plurality of substantially parallel, spaced-apart ridges extending from the substrate forming vertical liquid manifolds therebetween. A nanoporous membrane is supported on the ridges and a pump delivers a dielectric fluid across the ridges. The fluid is drawn through the liquid manifolds via capillarity provided by the nanoporous membrane and evaporates to dissipate heat flux through the substrate. A preferred dielectric fluid is pentane. It is preferred that membrane porosity vary across the membrane to tailor thermal resistances to limit temperature rises.

The invention belongs to the technical field of membrane science and provides a preparation method for a porous superhydrophobic membrane with structural gradient changes. The preparation method includes the following steps: utilizing a plasma technology to modify a basement membrane so that the porosity of the membrane can be increased; respectively adopting a coating method and an in-situ sol-gel method to prepare composite membranes with gradient changes of micron and nanoscale structures; and utilizing the surface chemical reaction of a low surface energy substance to obtain a superhydrophobic membrane through modification. The method utilizes plasma treatment to increase the surface porosity of the basement membrane; the basement membrane is coated with micron-sized particles; nanoscale particles can be generated on the surface of the basement membrane and the micron-sized particles in-situ; and the prepared superhydrophobic membrane can have characteristics of porousness and structural gradient changes by regulating the sizes and load capacity of the microparticles and nanoparticles on the surface of the basement membrane. The preparation method solves the problem of membranehole blockage caused by the direct coating method; new ideas of constructing multi-level rough structures can also be provided; and the preparation method is simple and low in cost, so that the preparation method has wide application prospects in the field of membrane separation.

The invention relates to a structure control method of the outer surface of a polypropylene separation membrane. The method comprises the steps that: (1) polypropylene and a diluent are added into a kettle with a stirring device; the mixture is heated and stirred, such that a membrane casting solution is prepared; (2) the membrane casting solution is filtered by using a filter; an inner core liquid is introduced into a spinning nozzle; the inner core liquid and the membrane casting solution are extruded by the spinning nozzle; the mixture is cooled and cured through 0-20 DEG C coagulation bath, such that a hollow fiber membrane is obtained; (3) the hollow fiber membrane is wound by using a winding machine, and is extracted in one or a plurality of extraction agents; and (4) the extracted membrane is fetched and dried; and the extraction agent is removed, such that the polypropylene hollow fiber separation membrane is obtained. According to the invention, variety and temperature conditions of the coagulation bath are improved, such that a problem of polypropylene separation membrane outer surface compact skin is solved. Polypropylene separation membrane porosity is improved from 44% to approximately 70%, and polypropylene separation membrane pore size is reduced from 0.45 to approximately 0.25. The increasing of porosity and the reduction of pore size show that the membrane pores are more uniform, and the probability of large pores is reduced or eliminated.

The invention discloses a method for synthesizing a nano silicon dioxide modified PVDF (polyvinylidene fluoride) hydrophobic microporous membrane in situ. The method comprises: preparing a PVDF solution, preparing a solution containing nano silicon dioxide, preparing a casting solution, casting, forming a membrane, drying and the like. According to the invention, the excellent characteristics of the PVDF hydrophobic microporous membrane are maintained, at the same time, the microstructure of the PVDF hydrophobic microporous membrane is improved, the membrane pore size, the membrane porosity and the membrane hydrophobicity are increased, the agglomeration of nanoparticles in the casting solution is overcome, the dispersibility of the nano silicon dioxide in the casting solution is improved,the hydrophobicity, membrane flux, chemical stability and membrane strength of the PVDF hydrophobic microporous membrane are enhanced, and the problem of reduction of the membrane flux caused by poordispersibility, prone agglomeration and easy blockage of membrane pores of the nanoparticles in the casting solution when inorganic nanoparticles are modified in the preparation of the PVDF hydrophobic microporous membrane is solved, so that the membrane is endowed with the characteristics of large water flux, high membrane flux, high hydrophobicity, high mechanical strength, and stable chemicalproperties.

The invention relates to a low-shielding large-area perovskite solar cell which has component photoelectric conversion efficiency of 14% to 15%. According to the perovskite solar cell, a light absorption layer porous skeleton is a porous skeleton thin film formed by doping tin oxide transparent conductive nano particles and transparent nonconductive nano particles Al2O3, ZrO2 or SiO2 and carrying out high-temperature sintering, a porosity of the thin film is 30% to 50%, a porosity diameter is 5 to 20nm, a thickness of the thin film is 400 to 800nm, light transmittance is 80% to 95%, and a surface square resistance is 102 to 103ohm; a perovskite absorbing material is a smooth and uniform CH3NH2PbI3 crystallized film; and a hole transmission layer is a smooth and uniform molybdenum trioxide-silicon dioxide gel film. According to the low-shielding large-area perovskite solar cell disclosed by the invention, by regulating and controlling light transmittance, the porosity and the surface square resistance of the light absorption layer porous skeleton, shielding of the porous skeleton for the sunlight is reduced, light transmission is improved, electrical conductivity is improved, and photoelectric conversion efficiency of the large-area perovskite solar cell is improved.

The invention provides a lithium ion battery and its preparation method. The lithium ion battery comprises a housing, an electrode group and an electrolyte, and the electrode group and the electrolyte are sealed in the housing, the electrode group comprises a positive electrode, a negative electrode and an inorganic membrane arranged between the positive electrode and the negative electrode, the inorganic membrane includes lithium manganese phosphate and a binder, in relative to 100 parts by weight of the lithium manganese phosphate, the content of the binder is 1-15 parts by weight; and the inorganic membrane porosity is 30-80%. The prepared lithium ion battery has the advantage of inorganic membrane safety performance, the charge and discharge capacity of the battery is higher, and the cycling performance is better.

The invention discloses a preparation method of a three-dimensional hydrophobic tubular nanofiber membrane. The preparation method comprises the following steps: uniformly dissolving a hydrophobic polymer in a mixed solvent to form a first membrane casting solution; taking a solution of hydrophobic nanoparticles as a second membrane casting solution; respectively putting the first membrane castingsolution and the second membrane casting solution into a first spinning injector and a second spinning injector, and collecting nanofibers on a receiver filled with a tubular support material under certain conditions; and taking down a tubular braided tube after spinning, and volatilizing solvents to obtain the nanofiber membrane, wherein the first spinning injector and the second spinning injector are located on the front upper portion and the rear upper portion of the receiver respectively and located in a plane which passes through the center of the receiver in the width direction and is perpendicular to the axis of the receiver. The membrane prepared by using the method is high in porosity, high in mechanical strength, good in thermal stability, good in lipophilicity and hydrophobicity and excellent in separation stability and reusability, and has long-time separation efficiency of greater than 95%.

The invention provides a cellulose polymer electrolyte membrane, and a preparation method and application thereof. According to the invention, cellulose is used as a raw material, so the membrane has high porosity, electrolyte absorption performance and electrolyte retention performance due to reassembling of molecular structures of cellulose and a great amount of mesoporous structures among the molecular structures and is thus improved in ionic conductivity; and the membrane has good mechanical properties due to action of a great number of hydrogen bonds among the molecular chains of cellulose and formation of a three-dimensional homogeneous system. The cellulose polymer electrolyte membrane provided by the invention can be repeatedly folded, has good surface flexibility and transparency, abundant mesoporous structures and adjustable pore diameters; the pore diameters become larger and more uniform with prolongation of humidification time; the cellulose polymer electrolyte membrane porosity of 71.78%, ionic conductivity of 0.325 s/cm and good mechanical properties. As the cellulose polymer electrolyte membrane provided by the invention is applied to a flexible all-solid-state supercapacitor and a minisized supercapacitor, the membrane has good electrochemical performance and the prepared supercapacitors have scalability.

The invention discloses a multifunctional load type nano multilayer composite membrane, and a preparation method and application thereof. The composite membrane comprises a polymer microporous supporting layer, an amination cross-linked transition layer and a nano-hybridized multifunctional skin layer. The preparation method comprises the following steps: preparing and generating the polymer microporous support layer on a super-hydrophobic rough substrate, and then preparing the aminated cross-linked transition layer and the nano-hybridized multi-skin layer in sequence. The polymer microporous membrane in the multifunctional load type nano multilayer composite membrane is high in porosity, large in aperture and high in water molecule permeation rate, and meanwhile, the super-hydrophobic rough surface prevents reverse circulation of water molecules; the aminated cross-linked transition layer is compact and has no defect, so that the separation performance of the membrane material is improved, and active sites are provided for loading of the nano material; and the nano-hybridized multifunctional skin layer can catalytically degrade small molecular substances, has a sterilization/bacteriostasis effect, prolongs the service life of the membrane material, complements advantages of multiple layers, couples multiple functions, and can realize seawater desalination, sewage purification, oil-water separation and the like.

The invention relates to a production method of a thermoplastic high-molecular material hollow fiber micro-pore membrane and belongs to the technical field of membrane separation. The method includes the following steps: 1) mixing a thermoplastic high-molecular material and CAB, of which the melting points are similar; 2) spinning the mixture through melt spinning method at 180-240 DEG C to prepare untwisted yarns; 3) drafting the untwisted yarns at 80-130 DEG C; 4) performing thermal treatment at 140-180 DEG C to obtain thermoplastic high-molecular material/CAB blended hollow fibers; and 5) placing the blended hollow fibers in acetone to dissolve the CAB phase to prepare the thermoplastic high-molecular material hollow fiber micro-pore membrane which is 30-45% in hollowness degree and 40-55% in porosity. The hollow fiber micro-pore membrane is high in porosity, is uniform in pore size distribution, is strong in mechanical performance and excellent in filtering performance, is low in processing cost, has a high additional value, is environment-friendly, and is an excellent basic material for the field of membrane separation.

The invention relates to a method using metal hydroxide nano fibers to prepare a high-throughput polyvinylidene difluoride (PVDF) porous film. The method includes the steps of firstly, adding the metal hydroxide nano fibers into a solvent, and stirring to prepare metal hydroxide nano fiber dispersion liquid; secondly, adding PVDF and a pore-forming agent into the metal hydroxide nano fiber dispersion liquid, evenly stirring, and ultrasonically defoaming to obtain film casting liquid; thirdly, using an immersion precipitation phase inversion process to scrape the prepared film casting liquid to obtain a flat PVDF film; fourthly, placing the flat PVDF film into an acetic acid solution to remove the metal hydroxide nano fibers, washing with deionized water, and airing to obtain the high-throughput PVDF porous film. Compared with a traditional method for preparing a teflon film, the method has the advantages that the porosity of the prepared polyvinylidene difluoride film is increased evidently, and the throughput of the film is increased evidently.

The invention relates to a full-ceramic diaphragm for a lithium ion battery and a preparation method thereof, and belongs to the field of diaphragm materials. According to the method, natural porous mineral diatomite is used as a main raw material, lithium carbonate and a small amount of titanium dioxide are added, a small amount of binder is used, high-temperature calcination is performed after compression molding, and the full-ceramic diaphragm for the lithium ion battery taking titanium-doped lithium silicate as the main component can be obtained. The thermal stability temperature of the full-ceramic diaphragm exceeds 800 DEG C, so that the problem of short circuit and fire in the battery caused by thermal shrinkage deformation of the diaphragm of the traditional lithium ion battery iseffectively avoided, and the safety of the lithium ion battery is remarkably improved. The full-ceramic diaphragm is high in porosity and large in liquid absorption rate, the titanium-doped lithium silicate component in the diaphragm can promote dissociation of lithium salt in electrolyte of the lithium ion battery, lithium ion transmission is promoted, and the capacity retention ratio of the battery during large-current charging and discharging and long-time operation is increased.

The invention discloses a hydrophilic single-layer porous membrane as well as a preparation method and application thereof, and belongs to the technical field of functional material preparation. The hydrophilic single-layer polymer porous membrane is finally prepared by preparing a membrane casting solution, scraping the membrane and utilizing a phase inversion method in sequence; by changing theinitial concentration of the membrane casting solution, the thickness of membrane scraping, the composition of a phase inversion solvent and the proportion of a mixed phase inversion solvent, asymmetric micro-nano holes with different pore sizes are controlled to be prepared in the opposite surfaces of the single-layer polymeric membrane, so that intelligent control on different permeation statesof the liquid is realized. The preparation method of the hydrophilic single-layer porous membrane disclosed by the invention is simple and feasible; the thickness, porosity and pore size of the prepared porous membrane are easy to control, and the porous membrane is low in cost, environment-friendly, safe, reliable and easy for industrial large-scale production, and can be well applied to the fields of liquid one-way permeation, dressings or functional textiles for quickly drying wounds and directional transportation.