Abstract: A process is provided for the selective oligomerization of C5 to C20 alpha-olefins to produce polyalphaolefin oligomers with a molecular weight distribution that is suitable for use in lubricant base oils.

Abstract: A coating for a medical device or appliance may include a fluoropolymer and a polyimide. Such coatings may provide a lubricious exterior surface that facilitates insertion or displacement of a medical device in a body lumen. Some coatings that include a fluoropolymer and a polyimide may, among other functions and characteristics, provide increased strength and/or durability relative to some other coatings.

Abstract: The invention concerns polyimide membranes, preferably composed of P84 type 70 or P84 HT, having improved chemical and physical properties, a method of producing same and also their use.

Abstract: The invention pertains to novel aromatic ether ketone polymers derived from bio-based feed-stocks, comprising recurring units of formula (Rb): wherein: —E is selected from the group consisting of: —each of R, equal to or different from each other, is selected from the group consisting of halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium; —j is zero or is an integer from 1 to 4, to a process for their manufacture and to the use of the same for manufacturing shaped articles.

Abstract: The present invention relates to new high-functionality, highly branched or hyperbranched polylysines, to processes for preparing them, and to their use.

Abstract: Provided are hyperbranched poly(ether-ketone)-based nanocomposites with the following generic formula: wherein n is the degree of polymerization and R is carboxylic acid (COOH) and various functional groups that could be derived from COOH, such as benzothiazole, benzoxazole, benzimidazole, esters, and amines. Also provided are a process for preparing the above composite and a chain-end conversion methodology to tailor thermal and solubility properties.

Abstract: A method for polymerizing 1,4-dioxane-2,5-diones in the presence of a generally protic initiator and at least one catalyst including at least one metal-free organic compound. The latter is a non-metal organic catalyst most often selected from among pyridines of which DMAP is a derivative, sulfonic acids, polycyclic tertiary amines, phosphazenes, thioureas, thioureas/amines, and guanidines. The invention also relates to polymers obtained by the method.

Abstract: A resin is based on ketones and aldehydes and is prepared in methanol or ethanol in the presence of a phase transfer catalyst. The resin features a very broad solubility and low intrinsic color.

Abstract: The present invention relates to a process for preparing polyketone with improved catalytic activity and intrinsic viscosity, and specifically a process for preparing polyketone, using a mixed solvent of 40 to 60 mol % acetic acid and 40 to 60 mol % water, as a liquid medium, and the precursor of palladium chloride-1,3-bis[di(methoxyphenyl)phosphino]propane, as a catalyst component.

Abstract: The present invention relates to new high-functionality, highly branched or hyperbranched polylysines, to processes for preparing them, and to their use.

Abstract: The invention relates to formaldehyde-free, carbonyl- and ring-hydrogenated ketone-aldehyde resins based on alkyl aryl ketones and formaldehyde and having a low OH-functionality, a low fraction of crystallisable compounds, low viscosity, very low colour number, and very high heat stability and light stability, and also to a process for preparing them.

Abstract: The invention relates to formaldehyde-free, carbonyl-hydrogenated ketone-aldehyde resins based on formaldehyde and having a low fraction of crystallizable compounds, low viscosity, very low color number, and very high heat stability and light stability, and also to a process for preparing them.

Abstract: The present invention provides crosslinkable compositions useful in the preparation of hydrophilic gels, and are prepared from polymers having pendent hydrophilic groups, and pendant Michael donor groups, and crosslinked by polyacryl Michael acceptor compounds.

Abstract: Functionalized porous poly(aryl ether ketone) articles are prepared by reacting ketone groups in the backbone of poly(aryl ether ketone) polymer with a primary amine reagent. Preferred functional primary amines are primary aliphatic amines or substituted hydrazines containing one or more target functional groups including polar groups, such as hydroxyl groups, ˜OH, amino groups, ˜NH2, ˜NHR, ˜NRR?, and ethylene oxide groups, ˜OCH2CH2—, negatively or positively charged ionic groups, such as ˜SO3?, ˜COO?, and ˜NH4+ groups, hydrophobic groups such as siloxane or perfluorcarbone groups, and non-polar groups, such as linear or branched hydrocarbon groups. The functionalized porous poly(aryl ether ketone) article can be prepared by reacting primary amine with a pre-formed, shaped porous poly(aryl ether ketone) article or by functionalizing the surface of a non-porous precursor article that is subsequently converted into a porous article.

Abstract: The present invention relates to a process for preparing polyketone with improved catalytic activity and intrinsic viscosity, and specifically a process for preparing polyketone wherein an organometallic complex comprising acetate-palladium and 1,3-bis[bis(2-methoxy-5-methylphenyl)phosphino]propane is used as a catalyst component, and a mixed solvent of 70 to 90 vol % of acetic acid and 10 to 30 vol % of water is used as a liquid medium.

Abstract: The present invention provides crosslinkable compositions useful in the preparation of hydrophilic gels, and are prepared from polymers having pendent hydrophilic groups, and pendant Michael donor groups, and crosslinked by polyacryl Michael acceptor compounds.

Abstract: A curable composition is described comprising a Michael donor component, a polyacryl component, and a monoacryl component, where at least one of the Michael donor or monoacryl components comprises a pendent photoinitiator group. A Michael addition polymer that is the Michael addition reaction product of these components is also described.

Abstract: Functionalized porous poly(aryl ether ketone) articles are prepared by reacting ketone groups in the backbone of poly(aryl ether ketone) polymer with a primary amine reagent. Preferred functional primary amines are primary aliphatic amines or substituted hydrazines containing one or more target functional groups including polar groups, such as hydroxyl groups, ˜OH, amino groups, ˜NH2, ˜NHR, ˜NRR?, and ethylene oxide groups, ˜OCH2CH2—, negatively or positively charged ionic groups, such as ˜SO3?, ˜COO?, and ˜NH4+ groups, hydrophobic groups such as siloxane or perfluorcarbone groups, and non-polar groups, such as linear or branched hydrocarbon groups. The functionalized porous poly(aryl ether ketone) article can be prepared by reacting primary amine with a pre-formed, shaped porous poly(aryl ether ketone) article or by functionalizing the surface of a non-porous precursor article that is subsequently converted into a porous article.

Abstract: Disclosed is a method for preparing a biodegradable polymer in the form of uniform powder or spherical particles by dispersion polymerization without a grinding step. The method for preparing a biodegradable polyester includes dispersing a monomer in the presence of a catalyst in a dispersion solvent to form a solid or liquid phase for dispersion polymerization and thereby to yield a biodegradable aliphatic polyester in the form of spherical particles or powder, the monomer comprising a mixture of a first compound (e.g., lactide or glycolide) and a second compound being selected from the group consisting of polyhydric alcohols (e.g., glycerin, erythritol, penterythritol or dipentaerythritol) and carprolactone. The present invention readily prepares a biodegradable polymer having a high molecular weight in the form of uniform powder or spherical particles.

Abstract: The invention described herein provides ketone-aldehyde resins, especially cyclohexanone-formaldehyde resins, with low water content and high thermal stability and yellowing resistance, and to a process for preparing them and their use.

Abstract: By the present invention, there are provided a catalyst for polyester preparation, which comprises a solid titanium compound containing titanium, oxygen, carbon and hydrogen and having a Ti—O bond and which has a maximum solubility in ethylene glycol, as measured when the catalyst is dissolved in ethylene glycol under heating at 150° C., of not less than 3,000 ppm in terms of a titanium atom, a catalyst for polyester preparation, which comprises a titanium-containing solution wherein a contact product of a hydrolyzate of a titanium halide or a hydrolyzate of a titanium alkoxide with a polyhydric alcohol is dissolved in ethylene glycol in an amount of 3,000 to 100,000 ppm in terms of a titanium atom, a process for preparing a polyester using the catalyst, and a polyester prepared by the process.

Abstract: There are disclosed polymeric or oligomeric product obtainable from the reaction of an anthraquinone with an aromatic diamine, characterised in that the anthraquinone is substituted or is not substituted and in that the diamine is a diamino anthracene which is substituted or is not substituted. The anthraquinone may be of the general formula (I): where, R may be the same as or different to R′, and may be a hydrogen atom (when R=R′=H, the compound is anthraquinone), or CH3, CH3CH2—, —OCH3, —OCH2CH3, —CH2OCH3, —CH2OCH2CH2OCH3, methoxyethoxyethoxymethyl, aryloxymethyl, phenyl, Cl, Br, CN or NO2, —CH2COOR or CH2NHCOR″ (where R″ is C1-C6 alkyl or a phenyl or biphenyl group).

Abstract: The invention concerns a process for preparing linear or branched sulphurous polymers such as polyarylene sulphides, in particular polyphenylene sulphide, from an aromatic dihalide compound and a sulphide in a solvent, wherein a) the aromatic dihalide compound and the sulphide are partially reacted; b) the resultant salt which is not dissolved in the reaction medium is separated off; and c) the reaction mixture largely freed of the salt is further polymerized.

Abstract: A photoactivatable reagent useful as a chain transfer reagent for providing a semitelechelic polymer having one or more terminal photoactivatable groups. The reagent provides one or more photoactivatable groups and one or more sulfhydryl (or other chain transfer) groups, the photoactivatable and chain transfer groups optionally being joined together by a spacer group. The reagent can be used to prepare a polymer by serving to initiate the polymerization of ethylenically unsaturated monomers. The reagent itself becomes an integral part of the resultant polymer, thereby providing the polymer with a terminal photoactivatable nature. The method provides a number of benefits, including the ability to provide homogeneous photoactivatable polymer compositions, e.g., in terms of the uniform location of the photogroup(s) on the terminal portion of each polymer molecule and the ability to build a desired nonpolar quality, and in turn improved surfactancy, into otherwise polar polymers.

Abstract: A polyketone solution is prepared by the dissolution of alternating aliphatic polyketone in a solution of ZnX.sub.2. X can be Cl, Br, or I. At a given temperature, these solvents completely dissolve polyketone when aqueous or organic solutions are made from particular concentrations.

Abstract: A magnetic recording medium has a substrate and an non-magnetic underlayer formed on the substrate and a magnetic layer formed on the non-magnetic layer. The magnetic layer include a magnetic powder and a binder for binding the magnetic powder on the non-magnetic layer. The binder includes at least a resin component containing at least an aminoquinone structure selected from an aminoquinone structure group shown with formulas (1-1) and (1-2) as a constitutional unit. As the magnetic powder, a metal magnetic powder mainly made of Fe and having a saturation magnetization .sigma.s is used. The magnetic layer has a saturation flux density Bm of 3500 to 5000 G and a coercive force of 1800 to 3000 Oe and a surface roughness SRa of 1 to 10 nm and a thickness of not more than 1.0 .mu.m.

Abstract: A process for the production of biodegradable aliphatic polyester particles by (co)polymerizing 2-oxetanone or a mixture containing at least 80% by weight of 2-oxetanone and up to 20% by weight of a cyclic ester or cyclic ether other than 2-oxetanone in the presence of a polymerization initiator supported on a carrier in which an ion polymerization initiator is supported on poly(2-oxetanone) in a liquid medium having a solubility parameter of about 15 to about 18 MPa.sup.1/2 and being capable of dissolving 2-oxetanone, and in a polymerizing apparatus having an internal surface formed of a material which is free of polarity or whose polarity is very small, to form a particulate aliphatic polyester; and a biodegradable aliphatic polyester melt-extrusion film, which comprises the biodegradable aliphatic polyester having a weight average molecular weight of 20,000 to 2,000,000, and having a water vapor transmission rate of 300 to 700 g/m.sup.2 .multidot.24 hours.multidot.25 .mu.

Abstract: Polyarylketones are made by electrophilic substitution using a dispersant for the polymer. The dispersant comprises a polymer having first pendent groups which are substantially compatible with the reaction mixture but are substantially incompatible with the polymer and second pendent groups which comprise Lewis bases. Preferred dispersants are copolymers of aliphatic vinyl compounds and N-vinyl pyrollidone, particularly of 1-eicosene (CH.sub.3 (CH.sub.2).sub.17 CH.dbd.CH.sub.2) and N-vinyl pyrollidone in which the ratio of first groups to second groups is in the range 1.5:1 to 0.5:1, and more preferably is 1:1.

Abstract: A process for the production of biodegradable aliphatic polyester particles by (co)polymerizing 2-oxetanone or a mixture containing at least 80% by weight of 2-oxetanone and up to 20% by weight of a cyclic ester or cyclic ether other than 2-oxetanone in the presence of a polymerization initiator supported on a carrier in which an ion polymerization initiator is supported on poly(2-oxetanone) in a liquid medium having a solubility parameter of about 15 to about 18 MPa.sup.1/2 and being capable of dissolving 2-oxetanone, and in a polymerizing apparatus having an internal surface formed of a material which is free of polarity or whose polarity is very small, to form a particulate aliphatic polyester; and a biodegradable aliphatic polyester melt-extrusion film, which comprises the biodegradable aliphatic polyester having a weight average molecular weight of 20,000 to 2,000,000, and having a water vapor transmission rate of 300 to 700 g/m.sup.2.24 hours.25 .mu.m and heat-fusing strength of 500 to 5,000 gf/15 mm.

Abstract: A process for the preparation of a linear alternating copolymer of carbon monoxide with ethene and another olefinically unsaturated compound (A) wherein a copolymer of which the molar ratio (r.sub.1) of the monomer units originating in the olefinically unsaturated compound A to the monomer units originating in ethene is in the range of from 1:100 to 1:3, is prepared by contacting the monomers in the presence of a liquid diluent with a catalyst composition which is based on(a) a source of a Group VIII metal, and(b) a bidentate ligand of the general formula R.sup.1 R.sup.2 M.sup.1 --R--M.sup.2 R.sup.3 R.sup.4 (I) wherein M.sup.1 and M.sup.2 independently represent a phosphorus, arsenic or antimony atom, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently represent unsubstituted or substituted hydrocarbyl groups and R represents a bivalent bridging group which consists of three atoms in the bridge of which the middle atom is a carbon or silicon atom which carries two monovalent substituents R.sup.5 and R.sup.

Abstract: Liquid polyamine crosslinking agent formulations based on trimerized toluylene 2,4- and/or 2,6-diisocyanate, with formation of an isocyanurate structure and hydrolysis of the isocyanate groups to amine groups, are described. The novel crosslinking agent formulations have a content of 40 to 80% of the total weight of the solids content of the crosslinking agent formulation of 1,3,5-tris-(3-amino-4-methyl-phenyl,2-methyl-3-aminophenyl) isocyanurate (I) which is not further condensed, and a content of not more than 1.0% of the total weight of the crosslinking agent formulations of toluylene-2,4- and/or -2,6-diamine (III). For the preparation, toluylene diisocyanate is trimerized, to form the isocyanurate structure, until 10 to 25% of the NCO groups have been reacted.

Abstract: The invention relates to novel compositions comprising ene and free radical adducts of unsaturated and saturated hydrocarbons, and acyclic and cyclic vicinal polycarbonyl compounds such as diethyl ketomalonate and indantrione. The adducts are reacted with nucleophiles such as amines, electrophiles such as anhydrides and esters, and metal ions. Post-products are obtained via reaction of said products with capping reagents such as boric acid. Compositions containing said adducts, products and post-products include oleaginous substances such as fuels and lube oils.

Abstract: Polyaryl ether ketones are prepared by electrophilic polycondensation using acyl halides as monomer components in the presence of a Lewis acid, by a process in which from 0.001 to 60% by weight of an inert filler or of a component which can be converted into an inert filler during working up are added to the reaction mixture before or during the polycondensation.

Abstract: The invention is an improved method for the preparation of poly-amine-quinone polymers using external oxidizing agents. The polymer produced has the general chemical formula: ##STR1## where each R is independently selected from the group of alkyl, cycloalkyl, aralkyl, aryl, silyl, siloxyl and the alkyl, alkoxy, aryl, carboxyl, amino, sulfhydryl, sulfoxyl, sulfonyl substituted derivatives thereof and n is about 50-2,000, and the molecular weight of the polymer is about 10,000 to 1,000,000, preferably about 10,000 to 40,000. The polymer can be used in anticorrosion paints and coatings, such as automotive and marine paints and coatings, and can also be used as a curing agent for epoxy resins.

Abstract: Synthesis of crystalline polyaniline, its derivatives and its co-polymers with other conjugated monomers by melt poly-condensation of bifunctional starting materials having a quinone and N-protected amine group, and conversion of such polycondensation polymers to corresponding doped and conductive form of said polymers.

Abstract: A method for the alkylsulfonation of polymeric and cyclic trimer phosphazenes that includes reacting the phosphazene with a sultone. This method can be used to prepare sulfonated phosphazenes that are useful as biomedical materials, membranes, reversibly cross-linkable polymers, surfactants, and polyelectrolytes.

Abstract: An RIM method of thermoplastic resin comprises a process for preparing materials in which one compound (i) is mixed with a material for thermoplastic resin to prepare one mixture (I), and the other compound (ii) is mixed with a material for thermoplastic resin to prepare the other mixture (II), each of two compounds (i) and (ii) being inactive to the material for thermoplastic resin but producing a high-active anionic polymerization catalyst by their reaction, a process for polymerization in which the mixture (I) and the mixture (II) are mixed, injected into a mold, and polymerized by the anionic polymerization catalyst, an ejecting process in which a solidified thermoplastic resin molded body is ejected from the mold. Therefore, a polymerization reaction cannot be started before the material for thermoplastic resin is injected into the mold, and it begins soon after the material for thermoplastic resin is injected into the mold.

Abstract: A polyketone is contacted with an organic peroxyacid in a reactive, oxidization, slurry process to produce a polyester polymer.

Abstract: Electroactive polymers are provided which contain alternating phenyl rings and nitrogen atoms, and which contain both quinoid mer units and benzenoid mer units. The polymers are formed by poly(condensation) of N-phenylhydroxylamine or derivatives thereof under anhydrous conditions in the presence of a Lewis acid catalyst. Methods for producing films, fibers and shaped articles of the polymers are provided as well.

Abstract: Disclosed herein are an aromatic thioether ketone/thioether sulfone random copolymer comprising phenylene thioether ketone recurring units (I) and phenylene thioether sulfone recurring units (II), (a) the compositional ratio (I:II) of the recurring units (I) to the recurring units (II) ranging from 98:2 to 65:35, (b) the solution viscosity (.eta..sub.inh) being at least 0.3 dl/g, (c) the melt crystallization time (.tau.) being at least 3 minutes, (d) the melting point (Tm) being 300.degree.-350.degree. C., (e) the glass transition temperature being at least 125.degree. C., (f) the retention (400.degree. C./20 min) of melt crystallization enthalpy (.DELTA.Hmc) being at least 60%, and (g) the average particle size being at least 0.1 mm, and the production process thereof.

Abstract: Reactive aminoquinones of formula I or II ##STR1## wherein R is hydrogen, branched, linear or cyclic C.sub.1 -C.sub.6 alkyl, aralkyl, or phenyl which may be substituted by linear, branched or cyclic C.sub.1 -C.sub.4 alkyl, --NO.sub.2, F, OR.sup.2, NR.sup.3.sub.2, wherein R.sup.2 and R.sup.3 are linear, branched or cyclic C.sub.1 -C.sub.6 alkyl, aralkyl or phenyl,R.sup.1 is a linear, branched or cyclic C.sub.2 -C.sub.18 alkylene chain, phenylene, aralkylene, alkarylene, or --(CH.sub.2 CH.sub.2 --O).sub.n --CH.sub.2 --CH.sub.2 --, wherein n is an integer from 1 to 50,X is hydroxy, epoxy, vinyl, vinyloxy, acrylate, methacrylate or acylchloroY is N or CH; andR.sup.4 is linear or branched C.sub.1 -C.sub.6 alkyl which are useful in forming copolymers to prepare corrosion resistant binder compositions for magnetic information storage media, the copolymers formed, the magnetic information storage media and a method for improving corrosion resistance in magnetic particles are provided.

Abstract: A polyketone is contacted with an organic peroxyacid in a reactive, oxidization, slurry process to produce a polyester polymer.

Abstract: This invention relates to a polyester comprising repeating units having the structure: ##STR1## wherein R.sup.1 is selected from the group consisting of hydrogen, alkyl having 1 to 6 carbon atoms and aryl having 6 to 10 carbon atoms and R.sup.2 is selected from the group consisting of hydrogen, alkyl having 1 to 6 carbon atoms, and aryl having 6 to 10 carbon atoms.

Abstract: This invention relates primarily to organofunctional monomers, predominantly dimethacrylates and/or diacrylates containing one or more (predominantly two carboxyl groups, with moieties that provide sufficient affinity with water to allow any desired amount of water and/or miscible fugitive solvents to be mixed homogeneously with these monomers and formulations containing them. The activity of water in the monomer formulations can be adjusted so that it is equal to the water activity in biological tissues. This promotes biocompatibility and enhances the adhesive characteristics of polymers prepared from these formulations. Probability statistics are disclosed that optimize the compositions of polymer reaction products.

Abstract: Electroactive polymers are provided which contain alternating phenyl rings and nitrogen atoms, and which contain both quinoid mer units and benzenoid mer units. The polymers are formed by poly(condensation) of N-phenylhydroxylamine or derivatives thereof under anhydrous conditions in the presence of a Lewis acid catalyst. Methods for producing films, fibers and shaped articles of the polymers are provided as well.

Abstract: A granular, high-melt-stable poly(arylene thioetherketone) has a solution viscosity (.eta..sub.inh) of at least 0.30 dl/g, a retention (400.degree. C./20 min) of melt crystallization enthalpy (.DELTA.Hmc) of at least 60%, a melting point of 340.degree.-360.degree. C., a glass transition temperature of at least 125.degree. C. and an average particle diameter of 0.1-2 mm. A production process of a granular, high-melt-stable poly(arylene thioether-ketone) comprises reacting an alkali metal sulfide and a dihalogenated aromatic compound consisting principally of a 4,4'-dihalobenzophenone in an organic amide solvent containing water. In the first step, (1) the ratio of the amount of the charged dihalogenated aromatic compound to the amount of the charged alkali metal sulfide is controlled to 0.95-1.2 (mole/mole), (2) the ratio of the water content to the amount of the charged organic amide solvent is controlled to 1-15 (mole/kg), and (3) the reaction is conducted for 3-30 hours at 180.degree.-260.degree. C.

Abstract: Aromatic polyimides with acetylenic end groups are cured by coupling together thermally or catalytically using cuprous salts as catalysts to increase molecular weight with little or no by-product formation. These polyimides can be shaped and formed prior to the coupling.The acetylenic end-capped aromatic polyimides are formed by the reaction of an aromatic dianhydride, an acetylenic organic monoamine compound which will provide the reactive end groups and optionally an aromatic diamine.

Abstract: Accordingly, novel carbonyl containing compositions are prepared by contacting, in the presence of a free radical initiator, a compound selected from the group consisting of saturated hydrocarbons, substituted saturated hydrocarbons, polymers and mixtures thereof with a carbonyl containing compound or mixtures thereof having the structures: ##STR1## wherein Q.dbd.HOH, MeOH, EtOH, or n-BuOH; n.dbd.0,1,>; and X and Y are independently selected from the group consisting of CH.sub.2, C.dbd.O; W is independently selected from the group consisting of CH.sub.2, C.dbd.O, O, NH, CMe.sub.2, C.dbd.N-alkyl and N-alkyl, wherein alkyl is 1 to 18 carbons; U and V are independently selected from the same groups as W and dependently selected so that U and V taken together are one of 1,2-phenylene, 1,8-naphthalene-diyl, and 1,2-naphthalene-diyl.

Abstract: A thermally stable polyimide which is blocked at the polymer terminal with a dicarboxylic acid anhydride represented by the formula (III): ##STR1## wherein Z is a divalent radical selected from the group consisting of a monoaromatic radical which is substantially unsubstituted or substituted with a radical having no reactivity with amine or dicarboxylic acid anhydride and has from 6 to 15 carbon atoms, a condensed polyaromatic radical or a noncondensed aromatic radical connected each other with a direct bond or a bridge member, and has a fundamental skeleton represented by recurring structural units of the formula (IV): ##STR2## and a process of preparing the polyimide.

Abstract: A readily processable polyimide being blocked at the terminal of a polymer molecule with a divalent radical derived from dicarboxylic acid anhydride represented by the formula (IV): ##STR1## wherein Z is a divalent radical selected from the group consisting of a monoaromatic radical which is substantially unsubstituted or substituted with a radical having no reactivity with amine or carboxylic acid anhydride and has from 5 to 15 carbons atoms, condensed polyaromatic radical or noncondensed aromatic radical connected each other with a direct bond or a bridge member, and having a fundamental skeleton represented by recurring structural units of the formula (III): wherein X and Y are --O-- or --CO-- and differ each other; preparation process of the polyimide; and resin composition containing the polyimide and fibrous reinforcement.