626 results about "Polyamic acid" patented technology

The invention provides a preparation method of an h-BN / PI high-temperature-resistant anticorrosive coating, and relates to the technical field of polymer composites.The preparation method of the h-BN / PI high-temperature-resistant anticorrosive coating comprises the steps that under the protection of inert atmosphere, aromatic diamine containing impurity element five-membered rings and aromatic dianhydride containing ether bonds are taken and subjected to a polymerization reaction in a polar aprotic solvent, and the h-BN / PI high-temperature-resistant anticorrosive coating is obtained. A polyamide acid solution is obtained; performing ultrasonic-assisted liquid phase stripping on the micron-sized hexagonal boron nitride to obtain single-layer hexagonal boron nitride; adding the single-layer hexagonal boron nitride into the polyamide acid solution for multiple times, and uniformly stirring to obtain a hexagonal boron nitride / polyimide composite solution; and coating the hexagonal boron nitride / polyimide composite liquid on a to-be-coated surface, and carrying out gradient heating curing to obtain the h-BN / PI high-temperature-resistant anticorrosive coating. The h-BN / PI high-temperature-resistant anticorrosive coating based on interaction of multiple hydrogen bonds has relatively good high temperature resistance, relatively good resistance mechanical property and excellent corrosion resistance.

The invention belongs to the technical field of aerogel, and particularly relates to high-conductivity aerogel powder as well as a preparation method and application thereof. The preparation method comprises the following steps: firstly preparing a graphene / polypyrrole nanosheet composite material with a three-dimensional structure, and then preparing the polyimide / graphene / polypyrrole ternary hybrid conductive aerogel by taking a polyamide acid solution as a precursor through a solution dipping and freeze drying process. Polyimide is used as a framework of high-conductivity aerogel powder, excellent mechanical strength and structural integrity are provided, the common brittleness problem of a pure graphene carbon material or polypyrrole conductive polymer aerogel is solved, and the three-dimensional graphene / polypyrrole nanosheet composite material has excellent elasticity and toughness and can be used for preparing a composite material with high conductivity. The polyimide aerogel prepared by the method can be dispersed in a polyimide matrix as a nano reinforcement, can effectively transfer stress and prevent crack propagation, and endows the aerogel with higher mechanical properties.

The invention belongs to the technical field of lithium ion batteries, and discloses a carboxyl-containing copolyimide binder, a lithium ion battery silicon negative electrode, a lithium ion battery and a preparation method, and polyamide acid is prepared by using a carboxyl-containing diamine monomer, an amino-terminated long aliphatic chain diamine monomer and an anhydride monomer as raw materials; and carrying out chemical imidization, precipitation and washing on the polyamide acid to obtain the carboxyl-containing copolyimide binder. The prepared carboxyl-containing copolyimide binder has good solubility in a conventional electrode manufacturing solvent, and the solution system of the obtained carboxyl-containing copolyimide binder is uniform and stable. When the carboxyl-containing copolyimide binder is applied to preparation of a silicon negative electrode of a lithium ion battery, the carboxyl-containing copolyimide binder can generate dual covalent interface interaction with silicon active material particles and conductive material particles, so that the migration efficiency of lithium ions in an electrode system is remarkably improved, the transmission dynamics performance is enhanced, and the high-rate charge-discharge capacity of the battery is effectively improved.

The invention discloses a wide-temperature energy storage aerogel / polymer composite material and a preparation method thereof.The preparation method comprises the steps that oxide aerogel with a three-dimensional skeleton structure is subjected to silanization treatment to obtain hydrophobic oxide aerogel, then the hydrophobic oxide aerogel is dispersed into a solvent to obtain dispersion liquid, and then the dispersion liquid is subjected to ultrasonic treatment to obtain the wide-temperature energy storage aerogel / polymer composite material. The preparation method comprises the following steps: sequentially adding a diamine monomer and an anhydride monomer into a dispersion liquid, reacting under stirring to obtain a polyamide acid precursor solution dispersed with hydrophobic oxide aerogel, carrying out film casting on the polyamide acid precursor solution to obtain a dry film, and carrying out imidization treatment on the dry film to obtain the aerogel / polymer composite material. The obtained aerogel / polymer composite material can still maintain high energy storage performance and stability even at extreme ambient temperature.

The invention discloses a high-temperature-resistant and corrosion-resistant coating for an aluminum alloy heat exchange tube and a preparation method thereof, and relates to the technical field of coating materials. The method comprises the following steps that the aluminum alloy heat exchange tube is cleaned and deoiled, then a treating agent is sprayed, composite coating slurry is sprayed to the surface of the aluminum alloy heat exchange tube after curing, and the high-temperature-resistant and corrosion-resistant coating for the aluminum alloy heat exchange tube is obtained after curing treatment. Wherein the treating agent is prepared from NS-30 silica sol, deionized water and methyltrimethoxysilane; the composite coating slurry is prepared from a polyamide acid solution, a synergist, functionalized boron nitride nanosheets, modified hexagonal boron nitride, a flatting agent and a defoaming agent. The silane film introduced into the treating agent and the synergist, the functionalized boron nitride nanosheet and the modified hexagonal boron nitride introduced into the composite coating slurry effectively improve the high temperature resistance, the corrosion resistance, the adhesive force, the thermal conductivity, the aging resistance and the toughness of the coating. Therefore, the method has a wider application prospect.

The invention relates to the technical field of vacuum bag films for aeronautical manufacturing, and discloses an eleven-layer co-extruded film for aeronautical use and a preparation process thereof, and the preparation process specifically comprises the following steps: carrying out grafting modification treatment on polyamide acid by using a monoalkenyl diepoxy composite flexible compound through a carboxyl-epoxy ring-opening reaction to prepare alkenyl functionalized processable polyimide; the preparation method comprises the following steps: carrying out modification treatment on nylon 6 resin by using 3-mercaptopropionic acid through an amino-carboxyl condensation reaction to prepare mercapto functionalized nylon; under the hot melting condition, alkenyl functionalized processable polyimide and sulfydryl functionalized nylon are induced to be subjected to reactive compounding through a free radical initiator, PA-PI alloy master batch is prepared, the master batch serves as a functional modification component of copolymerized polyamide 6 / 66 resin, an eleven-layer co-extrusion film is prepared through an eleven-layer co-extrusion blow molding process, and the eleven-layer co-extrusion film is used as a functional modification component of the copolymerized polyamide 6 / 66 resin. The film product has excellent comprehensive performance and can be used as a high-temperature-resistant vacuum bag film for curing aviation composite materials.

The invention belongs to the technical field of aerogel, and particularly relates to polyimide aerogel for 3D printing as well as a preparation method and application of the polyimide aerogel. According to the preparation method disclosed by the invention, the polyaniline with a curved surface structure is prepared by taking ice micro powder as a synthesis template of an aniline monomer, and the polyaniline / polyimide composite aerogel is prepared by adopting a polyamide acid in-situ compounding method. The polyaniline with the curved surface structure is a three-dimensional conductive unit, and when the polyaniline is dispersed in a polyimide matrix, the curved surface structures can be in contact with one another, so that an efficient three-dimensional conductive network is constructed in the composite material. The curved surface structure has a relatively large specific surface area, so that a relatively large contact area is formed between polyaniline and a polyimide matrix, stress is favorably transferred from the matrix to a filler, the polyaniline with the curved surface structure is favorably prevented from being agglomerated in the matrix, the polyaniline is more uniformly distributed, and the flexibility of the polyimide aerogel is improved.

Provided are: a liquid crystal aligning agent which contains two or more polyamic acids and in which deterioration in liquid crystal aligning properties when stored at room temperature is suppressed; a liquid crystal alignment film obtained from the liquid crystal aligning agent; and a liquid crystal display element. The liquid crystal aligning agent is characterized by containing the following polymer (A) and polymer (B). Polymer (A): a polyamic acid (A) having a structural unit derived from a tetracarboxylic acid derivative and a structural unit derived from a diamine, the polyamic acid containing, as the structural unit derived from the tetracarboxylic acid derivative, a structural unit (a-1Ta) represented by formula (1Ta), and containing, as the structural unit derived from the diamine, a structural unit (a-1Da) represented by formula (1Da), at least a part of the terminal of the polyamic acid (A) contains a non-amino group, the non-amino group is a functional group represented by structural formula (E), and the presence rate of the terminal amino group in the polyamic acid (A) is 60% or less based on the total terminal of the polyamic acid (A). Polymer (B): a polyamic acid (B) having a structural unit derived from a tetracarboxylic acid derivative and a structural unit derived from a diamine, the polyamic acid including a structural unit (b-1Tb) represented by formula (1Tb) as the structural unit derived from the tetracarboxylic acid derivative, and including a structural unit (b-1Db) represented by formula (1Db) as the structural unit derived from the diamine. (Definition of each symbol is as defined in the specification) (Definition of each symbol is as defined in the specification) (Definition of each symbol is as defined in the specification) (Definition of each symbol is as defined in the specification)

The invention belongs to the technical field of carbon fiber composite materials, and particularly relates to a carbon fiber reinforced composite material for an aerospace low-temperature storage tank and a preparation method of the carbon fiber reinforced composite material. The preparation method of the carbon fiber reinforced composite material for the aerospace low-temperature storage tank comprises the following steps: (1) preparing a polyamide acid prepolymer solution; (2) adding the polyamide acid prepolymer solution, a phosphorus-containing flame-retardant monomer and nano nitrile rubber into a solvent for reaction to prepare a sizing agent; (3) carbon fibers are soaked in the sizing agent, taken out and dried, and sized carbon fibers are obtained; and (4) mixing nano nitrile rubber with a resin matrix, and then carrying out prepolymerization and thermal imidization curing molding on the mixture and the sized carbon fibers to obtain the carbon fiber composite material. The carbon fiber reinforced composite material obtained by the invention not only has excellent liquid oxygen compatibility, but also can maintain excellent leakage resistance and mechanical properties in an extremely high and low temperature cycle environment, and provides technical support for application of aerospace low-temperature storage tanks.

The invention discloses a binder and a preparation method thereof, a negative pole piece and a battery, and belongs to the technical field of batteries. The binder provided by the invention is a copolymer of linear polyamide acid and a diamino-containing aromatic compound; wherein the linear polyamide acid is a copolymer of a dianhydride monomer and a diamine monomer. The binder can alleviate the problem of volume expansion of the silicon-carbon negative electrode so as to alleviate the problem of capacity fading, and also can alleviate the capacity deterioration caused by the falling of active substances in the circulation process of the pole piece; and the conductivity of the pole piece is improved to a certain extent, and the dynamic performance of the battery is facilitated.

The application relates to the technical field of aerogel fiber preparation, and discloses a polyimide aerogel fiber and a preparation method and application thereof. The preparation method comprises the following steps: preparing a polyamide acid precursor spinning solution; spinning the polyamide acid precursor spinning solution through a wet spinning method, winding and standing in a coagulation bath to obtain a polyimide wet gel fiber; and performing solvent replacement on the polyimide wet gel fiber and rapidly drying the polyimide wet gel fiber under normal pressure to obtain a polyimide aerogel fiber. The preparation method is simple, avoids the use of a lengthy drying process and expensive drying equipment, and successfully realizes continuous molding preparation, and has a good large-scale preparation prospect. The aerogel fiber prepared by the application has excellent tensile strength, which can reach 20.5 MPa; and has low density (0.34-0.53 g.cm ‑3 -3), high porosity (63-76%) and excellent heat insulation performance, and the thermal conductivity can be as low as 36.9 W.m ‑1 -1.K ‑1 -1; and has good heat preservation effect in various complex occasions.

The invention discloses a preparation method of corona-resistant oil-water-resistant low-dielectric polyimide. The preparation method comprises the following steps: S1, dissolving a fluorine-containing diamine monomer in an organic solvent; s2, adding an anhydride monomer into the diamine monomer solution obtained in the step S1 to obtain a polyamide acid solution, adding inorganic nanoparticles, and uniformly stirring; s3, adding methacryloyloxy propyl cage type polysilsesquioxane into the solution obtained in the step S2 to obtain polyimide slurry; the ratio of the total molar weight of the anhydride monomer to the total molar weight of the diamine monomer is (0.8-1.2): 1, the total solid content of the sum of the anhydride monomer and the diamine monomer in the solution is 5-50wt%, the proportion of the nanoparticles in the total solid content of the solution is 0.5-30wt%, and the proportion of the methacryloyloxy propyl cage type polysilsesquioxane in the total solid content of the solution is 0.5-30wt%. According to the preparation method of the low-dielectric polyimide, the corona resistance and oil-water resistance of a polyimide material are improved, and meanwhile, the dielectric constant of the material is reduced. The invention also provides the low dielectric polyimide.

The invention relates to the technical field of special cables, and discloses a high and low temperature resistant composite insulating layer cable and a preparation method thereof.The cable comprises a conductor core and a composite insulating layer wrapping the conductor core, and the composite insulating layer comprises a high temperature resistant heat conduction core layer and a low temperature resistant elastic layer; the high-temperature-resistant heat-conducting core layer is prepared from the following raw material: polyamide acid; hexagonal boron nitride; alpha-phase silicon carbide; the preparation method comprises the following steps: adding gamma-amino propyl triethoxy silane; nano barium titanate; the low-temperature-resistant elastic layer is prepared from the following raw materials: vinyl terminated polydimethylsiloxane; performing hydrophobic treatment on fumed silica; a Karstedt catalyst; a hydrogen-containing silicone oil crosslinking agent; the average particle size D50 of the 1-ethynyl-1-cyclohexanol and the alpha-phase silicon carbide is 0.5 to 2 mu m. According to the invention, by adopting a microwave selective heating and interlayer heat conduction mechanism, efficient and high-quality integrated curing of the composite insulating layer is realized.

The invention relates to the field of polyimide films, and discloses a catalytic polyimide film preparation method, which comprises: S1, preparing a prepolymer, dissolving a fluorine-containing diamine monomer in a polar solvent, placing in a reaction kettle, adding an aromatic dianhydride monomer at a low temperature of 0-10 DEG C, stirring, mixing, and reacting to generate a polyamide acid solution; s2, primary catalysis: adding an organic base catalyst into the polyamide acid solution prepared in the step S1; s3, second-stage catalysis: after the step S2 is completed, adding a coordination type organic basic catalyst into the first-stage catalyst; and S4, film formation and post-treatment. Amidation and ring-closure reactions are promoted in stages through the synergistic effect of the double catalysts, the reaction rate matching performance is remarkably improved, accurate control over molecular chains is achieved, a high-purity polymer matrix with uniform molecular weight distribution and complete ring closure is obtained, and the structural uniformity and mechanical strength of the film are fundamentally improved; the structure defect caused by incomplete reaction under a traditional single catalytic system is avoided.

The invention relates to the technical field of film strain, in particular to a preparation and installation method of a film strain sensor and a harmonic reducer. The preparation and installation method comprises the steps that the surface of a workpiece to be installed is coated with a polyamide acid solution, then heating is conducted, and polyamide acid is subjected to dehydration cyclization to form a polyimide film attached to the surface of the workpiece to be installed; and then, forming a laser-induced graphene electrode pattern on the polyimide film. The harmonic reducer comprises a wave generator, a rigid gear, a flexible gear and a thin film strain sensor, the flexible gear is connected into the rigid gear in a toothed mode, and the wave generator is arranged in the flexible gear; the film strain sensor comprises a strain film and a graphene electrode, the graphene electrode is formed on the strain film, and the strain film is in direct contact connection with the surface of the flexible gear. Through the film strain sensor adhered to the surface of the workpiece to be installed, in-situ torque detection can be achieved, measurement errors, hysteresis, instability and the like caused by a glue joint layer are avoided, and measurement is more accurate.

The invention discloses a photosensitive polyimide, a negative photoresist and an application of the photosensitive polyimide in preparation of a film, the structure of the photosensitive polyimide is shown in the specification, X is a tetravalent organic group and is a residue X of a polyimide polymerization monomer tetracarboxylic dianhydride; y is a divalent organic group and is a residue Y of a polyimide polymerization monomer diamine; r1 and R2 are monovalent organic groups and are residues of primary alcohol forming side chain ester bonds of side chain polyamic acid ester; side chains R1 and R2 at least contain tertiary amine structures, and at least one of the side chains R1 and R2 containing the tertiary amine structures can form ammonium salt with phosphate containing an allyl structure; and n is an integer from 2 to 150. The invention provides a photosensitive polyimide which can be developed by adopting an alkaline aqueous solution, can be cured at low temperature and can form a negative pattern, a preparation method of a photoresist composition of the photosensitive polyimide, and a photoetching curing film, which can be applied to display industry or semiconductor industry as an insulating layer, a passivation layer or an interlayer dielectric layer and the like.

The invention discloses a fireproof flame-retardant battery diaphragm, a preparation method thereof and a fireproof flame-retardant battery, and relates to the technical field of battery diaphragms. When the fireproof flame-retardant battery diaphragm is prepared, boric acid diglyceride and chlorinated trimellitic anhydride mixed liquor react to prepare a flame-retardant monomer; the preparation method comprises the following steps: polymerizing 4, 4 '-diaminodiphenyl ether and a flame-retardant monomer, and carrying out electrostatic spraying to prepare polyamide acid microspheres; dehydrating and drying the polyamide acid microspheres to obtain polyimide microspheres; performing etching-acidification on the polyimide microspheres to prepare carboxylated polyimide microspheres; allyl phosphoric acid and acrylic acid are copolymerized and grafted on the surface of a polyethylene film to prepare a modified polyethylene film; and coating the surface of the modified polyethylene film with the carboxylated polyimide microspheres to prepare the fireproof flame-retardant battery diaphragm. The prepared fireproof flame-retardant battery diaphragm has excellent flame retardance, wetting performance and thermal stability.

The invention relates to the technical field of diaphragm materials, in particular to a polyimide aerogel diaphragm material and a preparation method thereof. The embodiment of the invention provides a preparation method of a polyimide aerogel diaphragm material. The preparation method comprises the following steps: preparing a spinning solution with polyamide acid as a solute; utilizing roll-to-roll spinning, and outputting the spinning solution through electrostatic spinning / spraying so as to prepare a film on a sheet-shaped substrate; and heating the film to obtain the polyimide aerogel diaphragm material. According to the polyimide aerogel diaphragm material and the preparation method thereof provided by the embodiment of the invention, continuous, efficient and low-cost production of a polyimide aerogel diaphragm is realized, and the obtained product has excellent thermal stability, mechanical properties and electrochemical properties and is particularly suitable for a new energy battery diaphragm.

The invention provides polyamide acid ester, photosensitive polyimide resin, a negative photoresist composition and application thereof. A covalent bond on a side chain of the polyamic acid ester contains a benzoylmethyl-containing structure, the structure has an ultraviolet light sensing function and can realize light degradation, so that the polyamic acid ester is converted into polyamic acid and primary alcohol, and the formed polyamic acid can be dissolved in a water-based developing agent, so that the targets of water-based developing and photoetching are realized. Besides, after the polyamic acid ester provided by the invention is imidized, no crosslinking component is left, and the polyamic acid ester has high mechanical property, high resolution, high film thickness and depth-to-width ratio gt; and 2.0, good performance can be achieved even if low-temperature curing is carried out.

The invention relates to the technical field of lithium-ion solid-state batteries, in particular to a three-dimensional polymer modified intermediate layer for a lithium-ion solid-state battery and a preparation method of the three-dimensional polymer modified intermediate layer, and the preparation method comprises the following steps: adding polyacrylonitrile into N, N-dimethylformamide, and stirring until the polyacrylonitrile is completely dissolved; and then adding the modified polyamide acid-phosphonate copolymer, continuously stirring to obtain an electrostatic spinning precursor solution, and carrying out electrostatic spinning on the electrostatic spinning precursor solution to obtain the composite nanofiber membrane. According to the invention, the indium-containing heterocyclic modified diamine is used as a core monomer of the polyamide acid-phosphonate copolymer, the lithium deposition nucleation overpotential can be reduced by the excellent lithium-loving activity of the indium-containing heterocyclic modified diamine, the lithium is enabled to be compact and free of dendritic crystal deposition, and the indium-containing heterocyclic group is uniformly dispersed in a three-dimensional framework through a cross-linked network of the modified polyamide acid-phosphonate copolymer, so that the performance of the polymer is improved. The contact interface of the intermediate layer and the lithium metal forms a global uniform lithium-loving site, and concentrated deposition of lithium atoms caused by local lithium-loving activity difference is avoided.

The invention belongs to the technical field of aerogel, and particularly relates to high-strength conductive aerogel powder as well as a preparation method and application thereof. A high-conductivity polypyrrole composite material with a three-dimensional porous structure is prepared by taking thiolated graphene oxide as a carrier, polyamide acid salt is adopted as a precursor of polyimide, the solubility of the polyamide acid salt in a solvent is better, the solution is more stable, phase separation or gelation is not prone to occurring in advance, and uniform impregnation of the three-dimensional porous conductive material is facilitated; and the polyimide precursor is ensured to be fully permeated into pores of the graphene / polypyrrole network to form a more uniform composite structure. A polyimide framework in the aerogel powder wraps and fixes brittle graphene and polypyrrole in a three-dimensional network of the aerogel powder, so that the solvent resistance and the aging resistance of polypyrrole are improved, physical protection is provided for a conductive path, and the conductivity and the mechanical property of the composite material are improved.

The invention belongs to the field of electronic device protective coatings, and particularly relates to a water-based polyimide / POSS-GO composite coating and a preparation method and application thereof.The method comprises the steps that firstly, dianhydride and diamine monomers react to prepare polyamic acid, then tertiary amine is made into a salt agent to prepare water-soluble polyamic acid salt, and then the water-soluble polyamic acid salt is prepared into a water-soluble polyimide / POSS-GO composite coating; the preparation method comprises the following steps: modifying graphene oxide with aminated polyhedral oligomeric silsesquioxane to prepare a POSS-GO filler, uniformly dispersing the filler and water-based polyamic acid salt, spraying on the surface of a base material, and then carrying out thermal imidization treatment to prepare the water-based polyimide / POSS-GO composite coating. The composite coating prepared by the method is a novel coating material with excellent corrosion resistance and low dielectric property, not only provides a new thought for the design of a high-performance anticorrosive coating, but also provides a potential material strategy for a multifunctional protective coating of an electronic device.

The invention belongs to the technical field of coatings, and particularly relates to polyester resin for a powder coating as well as a preparation method and application of the polyester resin. The polyester resin for the powder coating is prepared from the following raw materials: polyol, polyacid, polyamide acid oligomer and an acidifying agent. The polyamide acid oligomer is introduced in the synthesis of the polyester resin, an amide structure in the polyamide acid oligomer can improve the electrification property of polyester, the improvement of the electrification property is beneficial to improving the powdering rate of powder, and meanwhile, an N-H bond in the amide structure has relatively strong polarity and hydrogen-bond interaction; the wettability of the base material is obviously improved through the synergistic effect of the two. Therefore, the polyamide acid oligomer is introduced into the polyester resin and is combined with other components, so that the corner coverage rate of the powder coating can be obviously increased.

This invention discloses an MPP pipe for power cables and its preparation method, relating to the field of polymer materials technology. The invention comprises, by weight, 80-90 parts of a toughening nucleating agent; 40-45 parts of an insulating nucleating agent obtained by in-situ composite and gradient temperature imidization treatment of a polyamic acid prepolymer prepared from hexagonal boron nitride nanosheets (prepared by surface modification with dopamine hydrochloride, followed by modification with octyltriethoxysilane) to obtain a silanized boron nitride suspension; 40-45 parts of melamine cyanurate; 2.1-2.4 parts of an antioxidant; 2.6-3 parts of a light stabilizer; 8-9 parts of a lubricant; and 1340-1500 parts of polypropylene. The introduction of the toughening nucleating agent and insulating nucleating agent in this invention effectively improves the flame retardancy, low-temperature rigidity-toughness balance, and aging resistance of the MPP pipe.

Provided are: a liquid crystal aligning agent which contains two or more types of polyamic acids and which suppresses variations in the pretilt angle of a liquid crystal aligning film when stored at room temperature; a liquid crystal aligning film obtained from the liquid crystal aligning agent; and a liquid crystal display element. The liquid crystal aligning agent is characterized in that the liquid crystal aligning agent can form a liquid crystal alignment film with a pretilt angle of more than 0 degree and less than 3 degrees, and the liquid crystal aligning agent contains the following polymer (A) and polymer (B) or the following polymer (B) and polymer (B '). (Here, polymer (A) does not include polymer (B)) Polymer (A): a polyamic acid (A) having a structural unit derived from a tetracarboxylic acid derivative and a structural unit derived from a diamine, the polyamic acid containing, as the structural unit derived from the tetracarboxylic acid derivative, a structural unit (a-1Ta) represented by formula (1Ta) and containing, as the structural unit derived from the diamine, a structural unit (a-1Da) represented by formula (1Da). Polymer (B): a polyamic acid (B) having a structural unit derived from a tetracarboxylic acid derivative and a structural unit derived from a diamine, the polyamic acid containing, as the structural unit derived from the tetracarboxylic acid derivative, a structural unit (b-1Tb) represented by formula (1Tb), and containing, as the structural unit derived from the diamine, a structural unit (b-1Db) represented by formula (1Db). At least a part of the terminal of the polyamic acid (B) contains a non-amino group, the non-amino group is a functional group represented by structural formula (E), and the presence rate of the terminal amino group in the polyamic acid (B) is 60% or less based on the total terminal of the polyamic acid (B). Polymer (B '): a polyamic acid (B') having a structural unit derived from a tetracarboxylic acid derivative and a structural unit derived from a diamine, the polyamic acid containing a structural unit (b-1Tb) represented by formula (1Tb) as the structural unit derived from the tetracarboxylic acid derivative and not containing a structural unit (a-1Da) represented by formula (1Ta), and the polyamic acid containing a structural unit (b-1Da) represented by formula (1Ta) as the structural unit derived from the diamine as the structural unit derived from the diamine. The polyamic acid (B) contains a structural unit (b-1Db) represented by formula (1Db) or a structural unit (b-1Db ') represented by formula (1Db'), and the content of terminal amino groups in the polyamic acid (B ') is greater than 60% based on the total terminals of the polyamic acid (B). (Definition of each symbol is as defined in the specification) (Definition of each symbol is as defined in the specification) (Definition of each symbol is as defined in the specification) (Definition of each symbol is as defined in the specification) .

The invention relates to the technical field of high polymer materials, and particularly discloses modified polyamide, an acid dyeable nylon 66 fiber as well as a preparation method and application of the acid dyeable nylon 66 fiber. The acid dyeable nylon 66 fiber disclosed by the invention has in-situ leveling property, modified monomers, adipic acid and hexamethylenediamine are polymerized to obtain modified polyamide, then the modified polyamide is prepared into pre-oriented yarns, and the pre-oriented yarns are elasticized to obtain the acid dyeable nylon 66 fiber. The ionic group of the modified monomer has an in-situ retarding effect in the nylon 66 fiber and is not combined with a dyeing seat, and an excellent level dyeing effect and a high dye uptake can be obtained without using a leveling agent. The addition amount of the modified monomer is small, the molecular size of the modified monomer is similar to that of adipic acid and hexamethylenediamine monomers, adverse effects on a polymerization process and a nylon 66 molecular structure are small, and the prepared acid dyeable nylon 66 fiber has excellent mechanical properties. The preparation cost of the acid dyeable nylon 66 fiber is low, the process is simple and convenient, and the acid dyeable nylon 66 fiber has a wide application prospect.

The invention discloses amino-terminated hyperbranched polyamide acid as well as a preparation method and application thereof. The amino-terminated hyperbranched polyamide acid is formed by polymerizing an aromatic anhydride monomer, an aromatic triamine monomer and an aromatic diamine monomer; the mole numbers of the aromatic anhydride monomer, the aromatic triamine monomer and the aromatic diamine monomer are a, b and c respectively, a: (b + c) = 1: 1-1: 1.5, and the proportion of b to c is any proportion. The amino-terminated hyperbranched polyamide acid disclosed by the invention not only has abundant terminal amino groups, but also contains a large number of polar groups such as ether bonds, imidazole rings, amide groups and carboxyl groups in molecular chains. Therefore, a stable water-based colloid emulsion can be formed in the presence of water and a small amount of organic solvent, other auxiliaries are not needed, and the interface performance and the mechanical performance of the composite material can be greatly improved.

The application provides a kind of composite 3D printing ink and its preparation method and application, belong to 3D printing technical field.The composite 3D printing ink provided by the application includes polyamide acid salt, graphene oxide, photoinitiator and organic solvent;The polyamide acid salt has the structure shown in formula I.Using the composite 3D printing ink provided by the application for 3D printing, the printing product with excellent mechanical properties, thermal performance and high-precision customized geometric shape can be obtained, which greatly expands the application of 3D printing technology in high temperature and high strength field.

The invention provides a preparation method of a heat insulation aluminum profile, and belongs to the technical field of heat preservation materials, and the preparation method comprises the following steps: (1) depositing a polydopamine layer in a heat insulation cavity of the aluminum profile, and then grafting an amino silane coupling agent on the surface of the polydopamine layer to obtain a pretreated aluminum profile; (2) in an organic solvent, carrying out polymerization reaction on a diamine monomer, a dianhydride monomer and a cross-linking agent to obtain a polyamide acid precursor solution; (3) the polyamide acid precursor solution is injected into a heat insulation cavity of the pretreated aluminum profile, the pretreated aluminum profile is immersed into a coagulating bath to be subjected to phase inversion, and polyamide acid wet gel is formed; and (4) carrying out solvent replacement on the polyamide acid wet gel, and then carrying out gradient heating drying and thermal imidization treatment to obtain the thermal insulation aluminum profile. According to the preparation method, a chemical bonding interface of polydopamine and amino silane is constructed on the surface of the aluminum material, and in-situ injection-phase inversion and gradient normal-pressure drying processes are combined, so that the heat insulation performance and the mechanical stability of the aluminum material are improved.

The application provides a porous carbon nanofiber electrocatalyst loaded with cobalt / lanthanum hydroxide heterojunction and a preparation method. The preparation method comprises the following steps: adding 4,4-diamino diphenyl ether and pyromellitic dianhydride into a solvent, uniformly mixing, and preparing a polyamide acid precursor spinning solution; electrospinning the prepared polyamide acid precursor spinning solution to prepare polyamide acid nanofibers; immersing the prepared polyamide acid nanofibers in a mixed metal salt solution containing cobalt salt, lanthanum salt and zinc salt to prepare polyamide acid nanofiber precursors loaded with metal ions; and performing programmed temperature heat treatment on the prepared polyamide acid nanofiber precursors loaded with metal ions in a protective atmosphere to prepare the porous carbon nanofiber electrocatalyst loaded with cobalt / lanthanum hydroxide heterojunction. The prepared porous carbon nanofiber electrocatalyst loaded with cobalt / lanthanum hydroxide heterojunction has excellent electrochemical oxygen reduction reaction and oxygen evolution reaction bifunctional catalytic activity.