A fast-response thermoplastic shape-memory polyimide and a preparation method thereof, related to a polyimide and a preparation method thereof. The present invention aims to solve the problem in high-temperature conditions of slow shape recovery poor stability, and poor mechanical properties of a shape-memory polymer prepared by utilizing an existing method. The structural formula of the polyamide of the present invention is as represented by formula (I). The preparation method is: 1. preparation of a diamine solution; 2. preparation of an anhydride-terminated high molecular weight polyamic acid; 3. preparation of a viscous sol-gel; and, 4. preparation of the thermoplastic shape-memory polyimide. The thermoplastic shape-memory polyimide prepared per the present invention is provided with a very fast shape recovery rate and improved shape-memory effect. The present invention is applicable in the field of polyimide preparation.

The invention relates to a process for producing aromatic polyimides, comprising the following steps: (a) preparation of one or more solid salt(s) by reacting one or more aromatic tetracarboxylic acid(s) and one or more diamine(s) according to a mole ratio ranging from 0.95 to 1.05; (b) drying of the solid salt(s), (c) addition, to the dry salt resulting from step (b), of one or more compound(s) (C) comprising one or more group(s) chosen from a carboxylic acid group, an anhydride group, an ester group and an acyl chloride group; (d) solid-state polymerization of said solid salt(s) in the presence of the compound(s) (C).

The invention relates to a process for producing an aromatic polyimide, comprising the following steps: (a) preparing one or more salt(s) by reacting one or more aromatic tetracarboxylic acid(s) in the solid state and one or more diamine(s), optionally in the presence of one or more chain limiter(s), in the presence of one or more binder(s), comprising one or more organic liquid(s), in an amount of from 1% to 25% by weight relative to the total weight of the aromatic tetracarboxylic acid(s), of the diamine(s) and of the optional chain limiter(s), then; (b) polymerising the salt(s) obtained in step (a).

A polyimide resin containing a repeating structural unit of the following formula (1), a repeating structural unit of the following formula (2), and a repeating structural unit of the following formula (A) or a repeating structural unit of the following formula (B), a content ratio of formula (1) with respect to the total of formula (1) and formula (2) being from 40 to 70 mol %, and a content ratio of formula (A) or formula (B) with respect to the total of formula (1) and formula (2) being more than 0 mol % and 25 mol % or less: ##STR00001##
wherein R.sub.1 represents a divalent group having from 6 to 22 carbon atoms containing at least one alicyclic hydrocarbon structure; R.sub.2 represents a divalent chain aliphatic group having from 5 to 20 carbon atoms; R.sub.a represents a divalent group containing at least one aromatic ring which is bonded to a monovalent or divalent electron-attracting group; R.sub.b represents a divalent group containing SO.sub.2 or Si(R.sub.x)(R.sub.y)O wherein R.sub.x and R.sub.y each independently represent a chain aliphatic group having from 1 to 3 carbon atoms, or a phenyl group; and X.sub.1, X.sub.2, X.sub.a, and X.sub.b each independently represent a tetravalent group having from 6 to 22 carbon atoms containing at least one aromatic ring.

A method for using citraconic anhydride and itaconic anhydride as addition cure end caps in reactions for forming polyamic acid oligomers and polyimide oligomers, is provided. Prepregs and high temperature adhesives made from the resulting oligomers, as well as, high temperature, low void volume composites made from the prepregs, are also provided.

The present invention relates to a polyimide film and a preparation method thereof. According to the present invention, a polyamic acid solution having a high weight-average molecular weight may be obtained by adjusting viscosity and solid content of the polyamic acid solution, and thus, a desired polyimide film may be prepared therefrom. Furthermore, since a length of carbon chains rearranged during graphitization is increased, a graphite sheet having excellent thermal conductivity can be prepared from the polyimide film of the present invention. Also, since the polyimide film has improved windability by further including inorganic particles as a filler, it may facilitate the wind operation.

This application provides a polyimide fiber and a preparation method thereof. This method comprises first subjecting a dianhydride compound and a diamine compound to a polymerization reaction in a solvent to obtain a polyamic acid solution, wherein said diamine compound comprises a diamine having a structure of Formula 12 or Formula 13, wherein A is S or O; said dianhydride compound comprises one or more of dianhydrides having structures of Formula 14 and Formula 15; and t is 0 or 1; then subjecting said polyamic acid solution to spinning to obtain a polyamic acid fiber; and sequentially subjecting said polyamic acid fiber to imidization and thermal drawing to obtain a polyimide fiber. The polyimide fiber having the above structure has a higher rigidity and can introduce a hydrogen bond to provide an interaction between molecular chains so as to influence the arrangement of the molecular chain in the polymer and the crystallinity, which imparts more excellent mechanical properties to the polyimide fiber. The polyimide fiber obtained has a higher glass transition temperature (Tg) and a better heat resistance.

##STR00001##

A poly(amide-imide) copolymer that is a reaction product of a diamine represented by Chemical Formula 1, a diamine represented by Chemical Formula 2, a dicarbonyl compound represented by Chemical Formula 3, and a tetracarboxylic acid dianhydride represented by Chemical Formula 4, a composition for preparing the poly(amide-imide copolymer, and an article including the copolymer, e.g., a film are provided: ##STR00001## wherein, in Chemical Formulae 1 to 4, R.sup.a, L.sup.1, L.sup.2, n1, A, R.sup.3, X, R.sup.10, R.sup.12, R.sup.13, n7 and n8 are the same as defined in the specification.

A polyamic acid manufacturing system for manufacturing a polyamic acid is disclosed using, as raw materials, a first solution in which a polyaddition-type first polymerizable compound is dissolved and a second solution in which a polyaddition-type second polymerizable compound that reacts with the first polymerizable compound through polyaddition is dissolved. The polyamic acid manufacturing system may include: a first supply part for supplying the first solution; a second supply part for supplying the second solution; a first combining part; and a first reaction part, thereby producing a first polymerization solution in which the polyamic acid is dissolved. Further, the polyamic acid manufacturing system may include: a first supply step of supplying the first solution; a second supply step of supplying the second solution; a first combining step; and a first reaction step, thereby producing a first polymerization solution in which the polyamic acid is dissolved.

A resin composition comprises a modified polyimide compound, an epoxy resin, and a solvent. The modified polyimide compound has a chemical structural formula of

##STR00001##

the Ar represents a group selected from a group consisting of phenyl having a chemical structural formula of

##STR00002##

diphenyl ether having a chemical structural formula of

##STR00003##

biphenyl having a chemical structural formula

##STR00004##

hexafluoro-2,2-diphenylpropane having a chemical structural formula of

##STR00005##

benzophenone having a chemical structural formula of

##STR00006##

and diphenyl sulfone having a chemical structural formula of

##STR00007##

and any combination thereof, the epoxy resin and the modified polyimide compound are in a molar ratio of about 0.1:1 to about 1:1. A polyimide film and a method for manufacturing the polyimide film using the resin composition are also provided.