41 results about "Membrane thickness" patented technology

A method of making monovalent and multivalent anion selective membrane. Such membrane can be used for electrodialysis (“ED”) operation and applied towards the important Cl−—SO42− separation in lithium extraction. The membrane thickness is much less than 100 μm, preferably less than 50 μm, more preferably less than 40 μm, and most preferably 20-30 μm.

The invention relates to a preparation method of a microporous membrane based on PTFE (polytetrafluoroethylene) emulsion. The microporous membrane is obtained by taking the PTFE emulsion as a main body, mixing a water-soluble polymer material as a structural carrier, performing blade coating to form a membrane through a scraper blade, performing freeze pore forming and performing heat treatment. The PTFE membrane prepared by the method has a unique pore structure, and the thickness, porosity, section pore structure, membrane mechanical properties and the like of a membrane material can be regulated and controlled by regulating and controlling the composition of a structural carrier, blade coating conditions and freezing and sintering parameters. Compared with a PTFE membrane prepared through mechanical stretching, the method has the advantages of being simple in preparation process, uniform in pore structure, uniform in membrane thickness and the like, and can be suitable for precise separation of heterogeneous materials in a harsh separation environment.

This invention belongs to the field of membrane separation and functional membrane materials technology, and discloses a chiral graphene oxide-based separation membrane, its preparation method, and its application. The membrane is composed of graphene oxide and / or reduced graphene oxide sheets and a single-stranded DNA-single-walled carbon nanotube complex. The single-stranded DNA helically winds around the outer surface of the single-walled carbon nanotubes to form a one-dimensional chiral nanochannel and intercalates between the sheets, forming a three-dimensional chiral channel network connected in the membrane thickness direction. The preparation method includes: heating and decohexing salmon sperm double-stranded DNA in a urea-containing buffer to obtain single-stranded DNA; dispersing single-walled carbon nanotubes and then complexing them with the single-stranded DNA; further mixing with a graphene oxide or reduced graphene oxide dispersion; and vacuum filtration to form the membrane. This membrane exhibits a high separation factor for chiral enantiomers such as L / D-phenylalanine, with an excess value of up to 99.95% for L-phenylalanine enantiomers after multi-stage separation, making it suitable for the efficient separation of chiral drugs and amino acids.

The utility model discloses a device capable of adjusting the thickness of a lamination film, which relates to the technical field of lamination machines, and comprises a base, the top of the base is fixedly connected with a conveyor, a first fixing frame and a second fixing frame, the inner top wall of the first fixing frame is connected with two sliding frames in a sliding manner, the interior of each sliding frame is rotatably connected with a lamination film roller, and the lamination film roller is fixedly connected with the conveyor. The inner top wall of the first fixing frame is fixedly connected with a liquid dropping pipe, the liquid dropping pipe is fixedly communicated with a liquid conveying pipe, the two film spraying rollers are installed below the liquid dropping pipe, the distance between the two sliding frames is adjusted through a first adjusting mechanism, and therefore the gap value between the two film spraying rollers is adjusted, the film spraying liquid dropping speed is controlled, and the film spraying speed is improved. The surface of a material is scraped through the scraping plate, and the distance between the scraping plate and the material is adjusted by controlling the sliding rod to slide on the second fixing frame, so that the thickness of a coating film on the surface of the material is adjusted.

There is provided a porous membrane comprising: an upstream porous asymmetric layer having an asymmetric layer thickness and a porous structure that reduces passage of bacteria therethrough; a downstream porous isometric polymer layer in contact with the porous asymmetric layer, the porous isometric layer having an isometric layer thickness and a porous structure that reduces passage of bacteria therethrough; wherein the porous membrane has a total membrane thickness; and the isometric layer thickness is 45% to 80% (e.g., 48-80%) of the asymmetric layer thickness.

An object of an aspect of the present invention is to provide a new organic-inorganic hybrid membrane composite excellent in permeance and a relevant technique thereof. An organic-inorganic hybrid membrane composite in an aspect of the present invention includes a porous support layer and an organic-inorganic hybrid membrane formed on the porous support layer, an air permeation amount is 10000 L / (m2·h) or less, the organic-inorganic hybrid membrane contains a matrix polymer and a gas-selective inorganic filler, a contained amount of the gas-selective inorganic filler relative to the organic-inorganic hybrid membrane is 35% by mass or more, the gas-selective inorganic filler contains zeolite, a framework density in a case where all T elements of the zeolite are silicon is 16.0 T / 1000 Å3 or less, and a membrane thickness of the organic-inorganic hybrid membrane is 0.05 μm or more and 50 μm or less.

This invention relates to a membrane tension compensation method based on the detection of uniformity in the thickness of water-soluble membranes produced by dishwashing pods. Addressing the problem that membrane thickness distribution is sensitive to nonlinear tension disturbances under high-speed operation conditions during water-soluble membrane production, and that traditional thickness control methods struggle to achieve precise closed-loop compensation, this invention proposes a method that continuously collects cross-sectional thickness information of the membrane material, constructs a time-space thickness sequence, extracts thickness gradient topological features, combines a multidimensional tension sensitivity feature vector with a dynamic thickness gradient topological graph, and uses a layer-by-layer sparsely connected lightweight graph convolutional network to infer the tension compensation amount. After median filtering and denoising, the result drives the actuator to adjust in real time, achieving high-precision closed-loop compensation for the uniformity of the water-soluble membrane thickness. This method improves the sensitivity and stability of thickness control under nonlinear disturbance environments, while also possessing both real-time performance and computational efficiency.

A fuel cell nitrogen emission strategy adjustment method and system based on membrane thickness change belong to the field of fuel cells, and the method comprises the following steps: acquiring the real-time thickness of a proton exchange membrane at the current moment, if the real-time thickness is greater than the historical thickness, reducing the opening duration of a nitrogen discharge valve, and if the real-time thickness is less than the historical thickness, increasing the opening duration of the nitrogen discharge valve. According to the present invention, the existing nitrogen removal strategy is adjusted according to the thickness change of the proton exchange membrane, and the proton exchange membrane is thickened, such that the nitrogen permeating from the cathode to the anode is reduced, and the content of the nitrogen accumulated on the anode side is reduced so as to reduce the opening time of the nitrogen removal valve in the nitrogen removal strategy; thinning of the proton exchange membrane indicates that nitrogen permeating from the cathode to the anode is increased, the content of nitrogen accumulated on the anode side is increased, the opening duration of a nitrogen removal valve in the nitrogen removal strategy is increased, and by setting the more reasonable nitrogen removal duration changing along with the thickness of the membrane, it is guaranteed that anode nitrogen is fully discharged, meanwhile, excessive discharge of anode hydrogen is avoided, and the nitrogen removal efficiency is improved. And the reasonability of the nitrogen removal strategy is improved.

This invention is for membranes with precision nanopores (also known as precision nanopore membranes or PNM) offering exceptional permeability and selectivity for separation of gas mixtures. Other applications include microfiltration. The subject PNM has high precision nanopores directly connecting the opposite sides of the membrane, thus avoiding a torturous path fort gas transport of prior art nanoporous membranes. Pores are oriented generally perpendicular to the membrane surface and may occupy a large fraction of membrane surface area. This beneficially offers reduction in membrane thickness and reduced operating pressures. This arrangement offers allow extreme reduction in membrane thickness ensuring high permeability and low driving pressures. The PNM allow for a simplified construction of the separator and a process with much reduced energy consumption compared to current commercial practice.

This invention proposes a Zr-based membrane for separating benzene / cyclohexane and its preparation method. The Zr-based membrane includes Zr-BDC membranes, Zr-BDC-PAA, or Zr-BDC-PVA. A polymer is introduced into the Zr-BDC framework via a secondary growth method to improve the membrane's selectivity for separating benzene / cyclohexane. The Zr-based membrane is directly synthesized using an in-situ growth method, which is simple in process. By adjusting the membrane growth time, good benzene / cyclohexane separation performance is achieved. Zr-BDC-PAA or Zr-BDC-PVA membranes are organic-inorganic hybrid membranes. The addition of polymers can adjust the membrane's pore structure, enhance its polarity, improve the size selectivity for separating benzene / cyclohexane, promote the intercalation of the Zr-BDC membrane, and influence the membrane thickness to some extent. The Zr-BDC membrane, by adjusting the growth time, grows more densely and continuously, thus exhibiting good benzene / cyclohexane separation performance.

Provided is a polyolefin microporous membrane containing a polyolefin, having a bubble point of 0.04-0.30 MPa, and having a value obtained by multiplying the membrane thickness (μm) and the bubble point (Mpa) of 2.0-4.5.

The utility model discloses a waterproof roll thickness detection device, and relates to the technical field of waterproof rolls. The device comprises a mounting bottom plate and further comprises a mounting support fixed to the center of the upper end face of the mounting bottom plate, rolling assemblies are evenly distributed in the mounting support, driving assemblies are symmetrically distributed on the left side and the right side in the mounting support, and detection assemblies are arranged on the rear sides of the rolling assemblies. According to the utility model, when the outer wall of the swing column body is contacted with the upper limit contact, an alarm can be given to indicate that the sunken part of the waterproof coiled material has reached the limit depth and the waterproof effect is influenced, when the waterproof coiled material is contacted with the convex part, the swing column body can move towards the inner side, and when the outer wall of the swing column body is contacted with the lower limit contact, the waterproof effect is influenced. The device can detect the upper surface and the lower surface of the waterproof coiled material at the same time, and it is guaranteed that the detection result is more accurate.

This invention provides a method for preparing a water-stable MOF-808 membrane and its application in the removal of organic pollutants from saline wastewater. The preparation steps of the MOF-808 membrane are as follows: a polymer-modified or seed-coated porous support is subjected to a solvothermal reaction with a precursor solution; after the reaction, the membrane is washed and dried to obtain a polycrystalline MOF-808 membrane. The MOF-808 membrane prepared by this invention has good intergrowth properties and uniform membrane thickness. When used for dye desalination, the obtained MOF-808 membrane has a thickness of 4.37 μm. ‑2 h ‑1 bar ‑1 The membrane exhibits high permeation flux and a salt / dye separation coefficient of 287.3, demonstrating excellent long-term operational stability. It is characterized by low cost / energy consumption and high separation efficiency. Even under acid, alkali, salt, and heating conditions, the MOF-808 membrane remains stable. Based on these characteristics, this membrane material demonstrates excellent separation performance for organic pollutants in high-salt environments, providing a feasible solution for the removal of organic pollutants from saline wastewater.

The invention provides a method for preparing an ultramicro filter membrane based on spray deposition of bacterial cellulose nanofibers, which comprises the following steps of: applying the bacterial cellulose nanofibers on the surface of a microfiltration membrane with a macroporous structure by adopting a spray method, so that the bacterial cellulose nanofibers are stacked and deposited to form a selective separation layer to obtain a composite ultramicro filter membrane; the preparation method comprises the following specific steps: 1) dispersing bacterial cellulose nanofibers in water to prepare a bacterial cellulose aqueous solution with the mass fraction of not less than 0.04 wt%; (2) spraying the bacterial cellulose nanofiber aqueous solution obtained in the step (1) on the surface of a micro-filtration membrane, and controlling the spraying amount of bacterial cellulose nanofibers to be 0.15-0.3 mL / cm < 2 > to obtain a composite ultra-micro filtration membrane; and 3) naturally drying the composite ultramicro filter membrane formed by spraying in the step 2) in air. The method provided by the invention has the advantages of simple preparation process, high efficiency and environmental protection, can accurately regulate and control the aperture and the membrane thickness of the separation layer, and can regulate the flux of the membrane within a certain range. And meanwhile, the preparation of the large-size nanofiber membrane is successfully realized by the method disclosed by the invention.

The present invention relates to a method for preparing a microporous membrane based on a PTFE emulsion. The microporous membrane is obtained by using a PTFE emulsion as a main body, mixing same with a water-soluble polymer material serving as a structural carrier, forming a membrane by means of blade coating, forming pores by means of freezing, and performing a heat treatment. The PTFE membrane prepared in the present invention has a unique pore structure, and the thickness, porosity, sectional pore structure, membrane mechanical properties, etc. of the membrane material can be adjusted by adjusting the composition of the structural carrier, blade coating conditions, and freezing and sintering parameters. Compared with the preparation of a PTFE membrane by means of mechanical stretching, the present invention has the advantages of a simple preparation process, uniform pore structure, uniform membrane thickness, etc., and is suitable for accurate separation of heterogeneous materials in a harsh separation environment.

This utility model relates to the field of waterproof membrane testing technology, specifically disclosing a waterproof membrane thickness testing device, including a support frame for support, a winding assembly disposed on one side of the support frame, and a testing component mounted on the winding assembly. The winding assembly includes a winding rod and a movable rod. A pulley and a drive motor mounted on the bottom of the pulley are disposed at the bottom of the winding rod. The drive motor is mounted inside the support frame. This utility model uses a flaw detector (such as an ultrasonic flaw detector) to test the waterproof membrane. This flaw detector utilizes the principle of ultrasonic waves propagating in different media and reflecting at interfaces, accurately measuring the thickness of the membrane without damaging it. This avoids the inaccurate test results caused by traditional testing methods that damage the outer surface of the membrane and have difficulty controlling the degree of damage. It can accurately measure the thickness of the membrane and detect internal defects such as bubbles and cracks, greatly improving the comprehensiveness and accuracy of the testing.

The present application relates to the technical field of separation membrane, and in particular to a metal ring water channel membrane, a preparation method and application thereof, wherein after introducing a metal ring compound into a base membrane structure by using an interface polymerization technology, the microstructure of the base membrane can be effectively controlled, and a metal ring water channel membrane is successfully constructed. According to SEM verification, the thickness of the metal ring water channel membrane is about 163 nm, which is obviously thinner than the thickness of the base membrane without introducing the metal ring compound. The thinning of the base membrane thickness is beneficial to reducing the water molecule transmission resistance, and thus the water flux can be significantly improved. Meanwhile, through the synergistic effect of the metal ring compound and the base membrane, the interception performance of the base membrane can be optimized, and efficient selective interception of different types of dye molecules is realized. The test results of the membrane separation performance show that after introducing the metal ring compound into the base membrane, the water permeation efficiency is greatly improved, and the interception efficiency of various types of dye molecules is not reduced, and the synergistic balance of high flux and high interception rate is successfully realized.

The application discloses a kind of high-stability MOF membranes and its preparation and gas-liquid separation application.First, dense MIL-140s seed layer is deposited on porous support;Then it is placed in precursor liquid containing metal source and organic ligand, and gradually fills the gap between seed layer by coordination reaction of metal source and organic ligand through certain period of thermally induced growth, finally forming continuous well anastomosed MIL-140s membrane layer;Gas (liquid) body separation test shows that MIL-140s membrane has excellent gas-liquid separation performance.It is particularly pointed out that changing thermally induced growth temperature can significantly control and optimize MIL-140s membrane microstructure (such as crystal orientation, membrane thickness, intercrystalline defect, etc.), thereby changing MIL-140s membrane separation channel size and corresponding separation system.The above research results are expected to realize the directional design and controllable optimization of MOF membrane microtopography and separation performance, and have good industrial application prospect.

An object of the present invention is to suppress a defect in a carbon membrane for fluid separation use with a dense carbon layer formed on a porous carbon support. The present invention is a carbon membrane for fluid separation use, including a dense carbon layer formed on a porous carbon support, wherein X<Y when the ratio of the content of silicon atoms to the total content of carbon atoms and silicon atoms at the center position in the membrane thickness direction of the porous carbon support is X (atomic %), and the ratio of the content of silicon atoms to the total content of carbon atoms and silicon atoms at the position of 3 μm from the interface between the porous carbon support and the dense carbon layer to the porous carbon support side is Y (atomic %).

The invention relates to the field of fuel cells, and discloses a preparation method of a proton exchange membrane with MXene directionally arranged along the membrane thickness direction, and the preparation method comprises the following steps: 1, depositing a Ti3AlC2 film on the surface of a substrate through direct current magnetron sputtering; step 2, etching the Ti3AlC2 thin film by using an NH4HF2 solution, so as to prepare an MXene film; 3, the MXene film is cut in the radial direction; 4, carboxylating the MXene film obtained in the step 3, and modifying the MXene film by using a polymer containing amido to form an N-Ti bond; and step 5, soaking the modified MXene membrane in a Nafion solution, and carrying out drying, hot pressing and heat treatment to prepare the proton exchange membrane in which MXene is directionally arranged along the membrane thickness direction. The proton exchange membrane disclosed by the invention is based on Nafion and MXene, and the MXene is orderly and directionally arranged along the membrane thickness direction, so that the proton transmission curvature can be effectively reduced; and the modified MXene has a large amount of proton exchange capacity, and the thermal stability of the Nafion matrix can be improved.

The application relates to a cellulose composite virus-removing membrane and a preparation process thereof. The composite virus-removing membrane comprises a microporous membrane support layer and a cellulose layer. A region for capturing 40nm colloidal gold in the virus-removing membrane is D 40 The membrane layer junction is taken as a position with a membrane thickness of 0%, the liquid inlet surface is taken as a position with a membrane thickness of -100%, and the liquid outlet surface is taken as a position with a membrane thickness of 100%. A region with a membrane thickness of -10% to 0% is a pre-retention region. The absorption peak height of D 40 gradually increases in the pre-retention region. The absorption peak of D 40 is the highest in a region with a membrane thickness of 1% to 40%. The application further discloses a preparation process of the composite virus-removing membrane. The composite virus-removing membrane has a pre-retention region for the 40nm colloidal gold retention capacity, and the retention peak value is controlled to be in the cellulose layer, so that the pre-retention region has the impurity retention capacity but does not cause concentrated impurity retention. The composite virus-removing membrane not only has high pressure resistance, but also has high loading capacity.

The invention relates to a microsensor (10) for measuring a measurement variable, having: an edge region (14) which surrounds a free region (16) and is formed by multiple individual anchor elements (18) which are laterally offset with respect to one another perpendicularly to a normal direction (22) and each extend with a width (20) and a length (60) greater than the width (20) through a layer structure (24) formed in the normal direction (22); and also having at least one membrane (26) which is self-supportingly connected to the anchor elements (18) with a uniform membrane thickness (28) and, depending on the measurement variable, can be deflected into the free region (16) in the normal direction (22), starting from a membrane edge (32) formed by the connection (30) and extending along the connection (30) to the anchor elements (18), wherein, in the normal direction (22), the individual anchor elements (18) each have a uniform width (20) and a uniform length (60) along all of at least one first layer (36) of the layer structure (24) adjacent to the membrane (26) in the normal direction (22), and wherein, along their respective lengths (60), the anchor elements (18) are oriented parallel to the membrane edge (32) adjacent to the anchor elements (18) and / or at least at an edge section of the membrane edge (32) form an edge contour (68) forming a non-linear membrane edge (32).

The utility model relates to the technical field of waterproof coiled material production, in particular to a waterproof coiled material thickness measuring device, which is characterized in that when the waterproof coiled material thickness measuring device is used, a worker flatly lays a cut waterproof coiled material to be measured on a bottom plate and then rotates a two-way screw rod, and because the lower end of a movable block is abutted against and in sliding fit with the upper surface of the bottom plate, the thickness of the waterproof coiled material is measured; under the action of threaded connection, the two movable blocks can relatively move close to each other or away from each other, that is, the movable blocks can drive the mounting plate to synchronously move, the mounting plate drives the flattening pressing plate to synchronously move, and a gap is reserved between the flattening pressing plate and the bottom plate; the flattening pressing plate can be tightly attached to the waterproof coiled material, folding or edge warping of the waterproof coiled material is prevented, errors of measurement results are avoided, measurement accuracy and flattening performance are guaranteed, the waterproof coiled material thickness detection device is suitable for thickness detection of various waterproof coiled materials with different thicknesses, and reliability and consistency of the measurement results are guaranteed.

The application provides a hydrogen and methane separation method. The separation method comprises: carrying out membrane separation on mixed gas containing hydrogen and methane through a hollow carbon molecular sieve membrane, preferably, the pore size of the hollow carbon molecular sieve membrane is 0.3-0.9 nm, the hollow carbon molecular sieve membrane has a bimodal distribution of 0.35+ / -0.05 nm and 0.5+ / -0.05 nm pore size, and / or the membrane thickness of the hollow carbon molecular sieve membrane is 20-30 microns; and / or the diameter of the hollow carbon molecular sieve membrane is 160-230 microns; the carbon source for preparing the hollow carbon molecular sieve membrane is microcrystalline cellulose or cellulose acetate, preferably microcrystalline cellulose. The application separates the mixed gas containing hydrogen and methane by using a multi-stage hollow carbon molecular sieve membrane, and high molar concentration hydrogen can be obtained to meet the subsequent hydrogen terminal process requirements.

The present application belongs to the field of medical device technology, and in particular, relates to a manufacturing method, device and ultrasonic scalpel of an ultrasonic scalpel head, wherein the scalpel head includes a surface texture structure, and the method includes: determining a first dimension based on plane strain shear stress, a first direction axis coordinate value, a maximum value of contact normal stress, a friction coefficient, a normal line load, a comprehensive equivalent elastic modulus of a contact body, a circumferential coefficient and a first preset condition; determining a depth through a film thickness equation of a water vapor film based on a total thickness of a water vapor film and a surface water vapor film thickness outside a surface texture structure; determining a density of a surface texture structure based on a first dimension, a depth, a density friction curve and a second preset condition, wherein the density of a surface texture structure is the number of surface texture structures per unit area on a biological tissue surface; manufacturing a scalpel head of an ultrasonic scalpel based on the first dimension, depth and density of the surface texture structure; reducing the risk of biological tissue adhesion to the ultrasonic scalpel and improving cutting and coagulation efficiency.

The purpose of one embodiment of the present invention is to achieve a porous support-zeolite membrane composite having excellent separation performance. A porous support-zeolite membrane composite according to one embodiment of the present invention has a CF4 permeation amount of 5.0 * 10 <-9 > mol / (m < 2 >. S. Pa) or less, and the zeolite membrane has a membrane thickness of 15 [mu] m or less.

The invention relates to a method for regulating and controlling a cardiolipin-containing membrane structure by utilizing mid-infrared light and application, and belongs to the field of biophysical regulation and control. The method comprises the following steps: applying a mid-infrared electric field with specific frequency and intensity to the mitochondrial-like phospholipid bilayer membrane system containing cardiolipin, and triggering the change of membrane structure parameters and cardiolipin behaviors of the mitochondrial-like phospholipid bilayer membrane system. The method comprises the following steps: constructing a mitochondrial membrane model through CHARMM-GUI, applying alternating electric fields with different frequencies and intensities by using a GROMACS platform, analyzing by combining indexes such as membrane thickness, cardiolipin orientation angle and cardiolipin density distribution, and determining 53.04 THz and 53.16 THz as characteristic frequencies of cardiolipin; 0.7 V / nm is determined as the optimal intensity. The mid-infrared light non-contact operation is adopted, the method has the advantages of being high in frequency selectivity and reversible in regulation and control, moderate change of the membrane structure can be caused under the specific frequency and proper electric field intensity, and a theoretical basis is provided for light regulation and control of the mitochondrial function, drug delivery and disease intervention.

The present application relates to the field of membrane separation, in particular to a self-repairable ultra-thin polymer / hollow fiber composite membrane module and a preparation method thereof, the present application proposes to bind the hollow fibers on the center tube in a "bundling type", to establish a standardized membrane coating production line, to carry out orthogonal cross test on the polymer coating liquid coating process of different materials based on the membrane preparation process of differential pressure pore permeation method, to unify the corresponding membrane preparation parameters, to carry out rapid gas blowing and other post-treatment processes after the coating is completed, so as to realize relatively uniform membrane thickness and dense and defect-free membrane layer, and to avoid the blockage of the inner cavity of the hollow fiber; at the same time, after the crosslinking agent is reacted with the polymer chain amide, a large number of carboxyl groups will still remain on the crosslinking agent, so that the new chemical crosslinking reaction of carboxyl and amino group, carboxyl and carboxyl occurs under a certain temperature and time, so as to realize the self-repair of the membrane layer defects, and the self-repair still maintains good separation performance.

The present disclosure relates to a fluid-applied membrane for radon mitigation in construction applications. It is disclosed a fluid-applied membrane for radon mitigation in construction applications comprising a fluid composition comprising a paraffin-based hydrophobic phase forming a continuous matrix after curing; at least one polymeric binder selected from a list comprising: acrylic, styrene-acrylic, ethylene-vinyl acetate or hydrocarbon resins, or their combinations, and mineral fillers, with a density greater than 3.5 g / cm3, selected from a list comprising: barite, hematite, magnetite, tungsten powder, bismuth powder or combinations thereof, wherein the viscosity of the fluid composition ranges from 0.5 Pa.s to 5 Pa.s at 20°C, interacting with radon gas to prevent radon migration primarily by diffusion resistance and barrier continuity; wherein the fluid-applied membrane thickness, after curing at ambient temperature, ranges from 0.5 mm and 10 mm; wherein the cured membrane exhibits a radon gas diffusion coefficient of 1×10-13 m2 / s or lower, thereby acting as a diffusion barrier preventing radon migration from a sub-floor region into habitable spaces.

The application relates to the technical field of gas separation, in particular to an asymmetric copolyimide membrane and a preparation method and application thereof. The asymmetric copolyimide helium separation membrane with a selection layer thickness of 300 nm is prepared by optimizing casting solution conditions and using a non-solvent induced phase separation technology. The membrane is dense in the outside and porous in the inside, the helium permeability reaches 87 GPU, the membrane thickness is reduced by one order of magnitude compared with a self-supporting membrane, the membrane also has good gas separation selectivity, the membrane also has good gas separation performance when the helium feed composition is changed, and the membrane also has excellent impurity resistance and stable separation performance when impurities C2H6 and CO2 are introduced.