Abstract: Provided is a method for producing a non-colored polyester with a high molecular weight. The method is to produce a polyester represented by a general formula (2). This method comprises: a first step of heating, under the presence of an antimony catalyst, a compound represented by the general formula (1) at a heating temperature in a range of from a melting point of the compound to a temperature that is 10° C. higher than the melting point; and a second step of heating a solid product or viscous product obtained after the first step at a heating temperature in a range of from the melting point of the compound represented by the general formula (1) to 270° C.

Abstract: The polymer mixture comprises polybenzimidazole (PBI)/polyvinylbutyral (PVB). The weight ratio (PVB:PBI) of this mixture may range from 0.25-50:50-99.75 or 15-85:15-85. The coating is based upon the polymer mixture.

Abstract: A pervaporation membrane may be an acid-resistant polybenzidimazole (PBI) membrane. The acid-resistant PBI membrane may be a PBI membrane chemically modified by a process selected from the group consisting of sulfonation, phosphonation, cross-linking, N-substitution, and/or combinations thereof. The membrane may be thermally stabilized. A method for the dehydration of an acid material may include the steps of: contacting an acidic aqueous solution with a membrane of an acid-resistant polybenzidimazole; taking away a permeate stream rich in water; and taking away a concentrate steam rich in the acid material. The acidic aqueous solution may be acetic acid.

Abstract: A process for preparing polyetherimides at higher production rates and a liquid reaction mixture are disclosed.

Abstract: A method for the manufacture of a polyetherimide composition includes catalyzing the reaction of a dianhydride and an organic diamine with a catalyst selected from guanadinium salts, pyridinium salts, imidazolium salts, tetra(C6-24)aryl ammonium salts, tetra(C7-24 arylalkylene)ammonium salts, dialkyl heterocycloaliphatic ammonium salts, bis-alkyl quaternary ammonium salts, (C7-24arylalkylene)(C1-16alkyl)phosphonium salts, (C6-24aryl)(C1-16alkyl)phosphonium salts, phosphazenium salts and combinations thereof, optionally in the presence of a solvent.

Abstract: A method for the manufacture of a polyetherimide composition includes catalyzing the reaction of a dianhydride and an organic diamine with a catalyst selected from guanadinium salts, pyridinium salts, imidazolium salts, tetra(C6-24)aryl ammonium salts, tetra(C7-24 arylalkylene) ammonium salts, dialkyl heterocycloaliphatic ammonium salts, bis-alkyl quaternary ammonium salts, (C7-24arylalkylene)(C1-16alkyl) phosphonium salts, (C6-24aryl)(C1-16alkyl)phosphonium salts, phosphazenium salts and combinations thereof, optionally in the presence of a solvent.

Abstract: Polymers having a main chain having both aromatic units and aliphatic units (with repeating heteroatoms) and a side chain macromonomer are described. Methods of making these polymers using enzymatic synthesis and the applications of these polymers are also described.

Abstract: A method of preparing polycarbonate includes a steps of providing a melt reaction mixture and allowing the melt reaction mixture to react to build molecular weight, thereby preparing the polycarbonate. The melt reaction mixture has a dihydroxy compound, an ester substituted diaryl carbonate mixture, and a melt transesterification catalyst where the ester substituted diaryl carbonate mixture may contain acid-substituted phenol. The method also includes the step of adjusting the molar ratio of acid-substituted phenol, if present, to melt transesterification catalyst (acid-substituted phenol/catalyst) in the melt reaction mixture to an amount of less than 10.

Abstract: An aromatic liquid-crystalline polyester composition is provided, which comprises at least one compound selected from an aliphatic carboxylate aryl ester and an aromatic carboxylic anhydride; an aromatic liquid-crystalline polyester; and a solvent containing at least 30% by weight of a halogen-substituted phenol compound. Using the composition, an aromatic liquid-crystalline polyester film with a low viscosity in melting state can be obtained.

Abstract: The present invention is directed to low dielectric polymers and to methods of producing these low dielectric constant polymers, dielectric materials and layers, and electronic components. In one aspect of the present invention, an isomeric mixture of thermosetting monomers, wherein the monomers have a core structure and a plurality of arms, is provided, and the isomeric mixture of thermosetting monomers is polymerized, wherein polymerization comprises a reaction of an ethynyl group that is located in at least one arm of a monomer.

Abstract: It is an object of the present invention to manufacture high quality thermotropic liquid-crystalline polymer generating no low boiling gas and inducing no discoloration resulted from thermal degradation at high yield. To manufacture a liquid-crystalline polymer having 50 mol % or larger ratio of constitutive unit introduced from 4-hydroxybenzoic acid, the reaction is conducted under the presence of an acylating agent and of a catalyst quantity of aromatic sulfonic acid.

Abstract: An aromatic liquid-crystalline polyester having a small dielectric loss in a wide frequency region is provided. An aromatic liquid-crystalline polyester is provided that can manufacture a film having a small volume expansion by heating. An aromatic liquid-crystalline polyester substantially comprising a repeating structural unit originating in 2-hydroxy-6-naphthoic acid 30 to 80 mol %, a repeating structural unit originating in aromatic diol 35 to 10 mol %, and a repeating structural unit originating in aromatic dicarboxylic acid 35 to 10 mol %.

Abstract: In a method of producing a low dielectric constant polymer, a thermosetting monomer is provided, wherein the thermosetting monomer has a cage compound or aryl core structure, and a plurality of arms that are covalently bound to the cage compound or core structure. In a subsequent step, the thermosetting monomer is incorporated into a polymer to form the low dielectric constant polymer, wherein the incorporation into the polymer comprises a chemical reaction of a triple bond that is located in at least one of the arms. Contemplated cage compounds and core structures include adamantane, diamantane, silicon, a phenyl group and a sexiphenylene group, while preferred arms include an arlyene, a branched arylene, and an arylene ether. The thermosetting monomers may advantageously be employed to produce low-k dielectric material in electronic devices, and the dielectric constant of the polymer can be controlled by varying the overall length of the arms.

Abstract: The present invention provides a liquid-crystalline polyester resin which comprises monomer units derived from 2-hydroxy-3-naphthoic acid and/or 2-hydroxynaphthalene-3,6-dicarboxylic acid in an amount of 1-5000 mmol % based on the total monomer components of the resin and an alkaline metal compound in an amount of 10-3000 ppm as alkaline metal based on the total monomer components of the resin. The liquid-crystalline polyester resin of the present invention has good colorability, improved heat resistance and good mechanical properties.

Abstract: In a method of producing a low dielectric constant polymer, a thermosetting monomer is provided, wherein the thermosetting monomer has a cage compound or aryl core structure, and a plurality of arms that are covalently bound to the cage compound or core structure. In a subsequent step, the thermosetting monomer is incorporated into a polymer to form the low dielectric constant polymer, wherein the incorporation into the polymer comprises a chemical reaction of a triple bond that is located in at least one of the arms. Contemplated cage compounds and core structures include adamantane, diamantane, silicon, a phenyl group and a sexiphenylene group, while preferred arms include an arylene, a branched arylene, and an arylene ether. The thermosetting monomers may advantageously be employed to produce low-k dielectric material in electronic devices, and the dielectric constant of the polymer can be controlled by varying the overall length of the arms.

Abstract: An agent for imparting flame retardancy to a thermoplastic resin contains a polyhydric phenol such as a tannin compound as an effective component. The thermal stability of the thermoplastic resin can be improved so as to elevate the decomposition temperature of the thermoplastic resin if a small amount of the flame retardancy imparting agent is added to the thermoplastic resin so as to suppress the combustibility of the thermoplastic resin.

Abstract: Phenolic polymers are prepared by oxidizing and polymerizing starting organic compounds comprising at least one hydroxyl group and at least one carbonyl group or at least two hydroxyl groups on an aromatic structure. One or more inorganic compounds or salts is added and the solution is allowed to stand at about 20° C. to 80° C. for a period of about at least 2 hours. Salt molecules as well as starting compounds and other low molecular-weight materials below about 500 to about 10,000 daltons are removed from the product solution. Purified phenolic polymers are prepared in concentrated aqueous solution or in dried powder form in a final step if necessary. The resultant phenolic polymers exhibit physicochemical properties strongly resembling those of typical commercially-available natural-product soil extracts. The materials are active herpes anti-viral agents, and are effective in anti-viral compositions for treating or preventing human herpes viral diseases.

Abstract: In a method of producing a low dielectric constant polymer, a thermosetting monomer is provided, wherein the thermosetting monomer has a cage compound or aryl core structure, and a plurality of arms that are covalently bound to the cage compound or core structure. In a subsequent step, the thermosetting monomer is incorporated into a polymer to form the low dielectric constant polymer, wherein the incorporation into the polymer comprises a chemical reaction of a triple bond that is located in at least one of the arms. Contemplated cage compounds and core structures include adamantane, diamantane, silicon, a phenyl group and a sexiphenylene group, while preferred arms include an arylene, a branched arylene, and an arylene ether. The thermosetting monomers may advantageously be employed to produce low-k dielectric material in electronic devices, and the dielectric constant of the polymer can be controlled by varying the overall length of the arms.

Abstract: Phenolic polymers are prepared by oxidizing and polymerizing starting organic compounds comprising at least one hydroxyl group and at least one carbonyl group or at least two hydroxyl groups on an aromatic structure. One or more inorganic compounds or salts is added and the solution is allowed to stand at about 20° C. to 80° C. for a period of about at least 2 hours. Salt molecules as well as starting compounds and other low molecular-weight materials below about 500 to about 10,000 daltons are removed from the product solution. Purified phenolic polymers are prepared in concentrated aqueous solution or in dried powder form in a final step if necessary. The resultant phenolic polymers exhibit physicochemical properties strongly resembling those of typical commercially-available natural-product soil extracts. The materials are active herpes anti-viral agents, and are effective in anti-viral compositions for treating or preventing human herpes viral diseases.

Abstract: Phenolic polymers are prepared by oxidizing and polymerizing starting organic compounds comprising at least one hydroxyl group and at least one carbonyl group or at least two hydroxyl groups on an aromatic structure. One or more inorganic compounds or salts is added and the solution is allowed to stand at about 20° C. to 80° C. for a period of about at least 2 hours. Salt molecules as well as starting compounds and other low molecular-weight materials below about 500 to about 10,000 daltons are removed from the product solution. Purified phenolic polymers are prepared in concentrated aqueous solution or in dried powder form in a final step if necessary. The resultant phenolic polymers exhibit physicochemical properties strongly resembling those of typical commercially-available natural-product soil extracts. The materials are active human immunodeficiency anti-viral agents, and are effective in anti-viral compositions for treating or preventing human immunodeficiency viral diseases.

Abstract: Phenolic polymers are prepared by oxidizing and polymerizing starting organic compounds comprising at least one hydroxyl group and at least one carbonyl group or at least two hydroxyl groups on an aromatic structure. One or more inorganic compounds or salts is added and the solution is allowed to stand at about 20° C. to 80° C. for a period of about at least 2 hours. Salt molecules as well as starting compounds and other low molecular-weight materials below about 500 to about 10,000 daltons are removed from the product solution. Purified phenolic polymers are prepared in concentrated aqueous solution or in dried powder form in a final step if necessary. The resultant phenolic polymers exhibit physicochemical properties strongly resembling those of typical commercially-available natural-product soil extracts. The materials are active hemorrhagic fever anti-viral agents, and are effective in anti-viral compositions for treating or preventing hemorrhagic fever viral diseases.

Abstract: A method for producing polybenzazole, which comprises reacting a PBZ monomer salt with an AA-PBZ monomer or a BB-PBZ monomer in a non-oxidizing solvent having a dehydrating action to give an oligomer, and adding the AA-PBZ monomer or BB-PBZ monomer, which has not been subjected to the above reaction, to allow reaction with the oligomer, whereby to give a polymer having a desired polymerization degree. According to this method, the polymerization degree of the polymer to be obtained finally and of the polymer during production process can be easily controlled.

Abstract: The invention is directed to a hydrolytically polymerized polycaprolactam with new chain regulation, whereby the polymerization of caprolactam (I) is carried out with 0.1-0.7 weight percent of an aromatic dicarboxylic acid (II), 0.01-0.7 weight percent of an aliphatic or cycloaliphatic diamine (III) that carries a primary and a tertiary amino group, and/or 0.01-0.7 weight percent 4-amino-2,2,6,6-tetraalkyl piperidine (IV), whereby the quantities of constituents I through IV add up to 100 weight percent and the quantity of the constituents III and/or IV amounts to 0.01-0.7 weight percent.

Abstract: In a process for the preparation of poly-o-hydroxyamides and poly-o-mercaptoamides, a bis-o-aminophenol or a bis-o-aminothiophenol is reacted with a dicarboxylic acid derivative with the following structure:M--CO--R*--CO--Mwhere M stands for the residue of an (optionally substituted) 2-hydroxybenzoxazole, 2-hydroxybenzothiazole, or 1-hydroxybenzotriazole or of corresponding mercapto compounds and R* is the parent body of the dicarboxylic acid.

Abstract: In a process for the preparation of poly-o-hydroxyamides and poly-o-mercaptoamides, a bis-o-aminophenol or a bis-o-aminothiophenol is reacted with a dicarboxylic acid ester with the following structure:G--O--CO--R*--CO--O--G,where G is an (optionally substituted) succinimide or maleinimide group and R* is the parent body of the dicarboxylic acid.

Abstract: Disclosed are cosmetic melanins of different colors produced by procedures involving oxidative polymerization of monomeric precursors of melanin and/or co-monomers that enhance substantivity or adherence of the melanins to the skin and hair. Also disclosed are methods for preparing cosmetic melanins and methods for using these compositions topically to produce a natural-appearing tan and to prevent damage to skin caused by UV exposure.

Abstract: Process for the batchwise preparation of poly-p-phenylene terephthalamide polymer by means of reacting approximately equimolar amounts of p-phenylene diamine and terephthaloyl dichloride in a solution containing N-methyl-2-pyrrolidone and calcium chloride, with the reaction being carried out in a cylindrical reaction vessel equipped with a single mixing gear used as stirrer and granulator, the contents of the reaction vessel being whirlingly mixed as terephthaloyl dichloride is added, the formed polymer being crumbled, and the reaction and the crumbling taking place in one and the same reaction vessel. The whirling miming ensures that the terephthaloyl dichloride is very thoroughly mixed into the solution of N-methyl-2-pyrrolidone, calcium chloride, and p-phenylene diamine before the reaction between the reactants causes a very rapid increase in viscosity. The quality of She product obtained by this process is very high.

Abstract: The invention relates to polycarbonates (PC) terminated by allylphenols, preferably eugenol, and subsequently grafted with maleic anhydride (MA) in the melt, to their use as blending partners for polyamides (PA) and to the polycarbonate/polyamide blends.

Abstract: A process for preparing a polyhydroxystyrene having a novolak type structure which comprises the step of polymerizing a mixture of carboxylic acid and at least one substituted phenyl carbinol whose formula is: ##STR1## wherein (a) R.sub.1 is selected from the group consisting of H, alkyl C.sub.1 -C.sub.20, substituted and unsubstituted phenyl, and C(O)R.sub.8 (where R.sub.8 is alkyl C.sub.1 -C.sub.20); (b) R.sub.2 is selected from the group consisting of H and alkyl C.sub.1 -C.sub.20 ; and (c) R.sub.3 -R.sub.7 are each independently selected from the group consisting of H, alkyl C.sub.1 -C.sub.20, OR.sub.9 (where R.sub.9 is H, alkyl C.sub.1 -C.sub.20, esters thereof, or substituted and unsubstituted phenyl), halogen, BZT, nitro, or amino, with the proviso that at least one of R.sub.3 -R.sub.7 is OR.sub.9, in the presence of a suitable catalyst for a sufficient period of time and under suitable conditions of temperature and pressure to form said novolak type polymer.

Abstract: This invention relates to a method for the measurement and control of polyamides and polyamide precursor mixtures by means of near-infrared spectroscopy.

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 process for preparing a substantially chloride-ion-free, high-molecular-weight, colorless and transparent polycarbonate by melt-polycondensing a dihydric phenol with a carbonic diester, which comprises using a carbonic diester which is substantially free from (A) phenyl salicylate, o-phenoxybenzoic acid and phenyl o-phenoxybenzoate, (B) tin ion, (C) methyl phenyl carbonate or (D) phenyl salicylate and o-phenoxybenzoic acid.A process for preparing a thermally stable polycarbonate by melt-polycondensing a dihydric phenol with a carbonic diester, which comprises using a borate or, a compound selected from the group consisting of electron-donative amines and salts thereof as a catalyst, and optionally an acidic substance.

Abstract: Oligomeric monomers are produced by reaction of a bisphenol compound with ther a dihalobenzophenone or a (2,2)bis(4-halophenyl)hexafluoropropane and any other activated halogen containing aromatic compounds in the presence of a base and an appropriate solvent. The resulting oligomeric product, a dialkaline bisphenate terminated salt, is then reacted with 4-nitrophthalonitrile to form an oligomer-based phthalonitrile. These oligomers, in the presence or absence of an curing agent, may then be heated to form high temperature thermosetting polymers. These polymers can potentially be used as advanced materials for composites, as adhesives, and for microelectronic applications.

Abstract: Macrocyclic polyimide oligomers are converted to linear polyimides by heating with a primary amine in the presence of a tertiary amine, tertiary phosphine, quaternary ammonium salt, quaternary phosphonium salt or hexaalkylguanidinium salt or heterocyclic analog thereof as a macrocyclic polyimide polymerization catalyst.

Abstract: Novel compositions comprising a high concentration of one or more extended chain homopolymer, copolymer, or block polymer and certain polyphosphoric acids are prepared. Such compositions are optically anisotropic (liquid crystalline), capable of exhibiting excellent cohesive strength, and are especially suited to the production of high molecular weight ordered polymer fibers by dry-jet wet spinning. These liquid crystalline compositions are capable of being drawn through long air gap distances and spun at exceptionally high spin draw ratios. Fibers, films and other articles formed from these liquid crystalline compositions exhibit exceptionally high physical and heat resistant properties.

Abstract: Oligomeric monomers are produced by reaction of a bisphenol compound with ther a dihalobenzophenone or a (2, 2) bis (4-halophenyl) hexafluoropropane and any other activated halogen containing aromatic compounds in the presence of a base and an appropriate solvent. The resulting oligomeric product, a dialkaline bisphenate terminated salt, is then reacted with 4-nitrophthalonitrile to form an oligomer-based phthalonitrile. These oligomers, in the presence or absence of an curing agent, may then be heated to form high temperature thermosetting polymers. These polymers can potentially be used as advanced materials for composites, as adhesives, and for microelectronic applications.

Abstract: A two step solvent-free process for the preparation of polycarbonates having a low degree of branching is disclosed. Accordingly, the process comprise(i) transesterifying in the melt, at temperatures of from 80.degree. to 250.degree. C. and under atmospheric pressure and for a time of up to five hours of diphenols and carbonic acid diaryl esters in the presence of a catalyst to form an oligocarbonate having a weight average molecular weight of from 8,000 to 18,000 and an OH-end group content of from 25 to 50%, and(ii) polycondensing of said oligocarbonate at temperatures of from 250.degree. C. to 295.degree. C. and pressures of from <500 mbar to 0. 01 mbar,said catalyst being present in an amount of 10.sup.-1 to 10.sup.-8 tool of a catalyst per tool of diphenol, said catalyst being at least one member selected from the group consisting of quaternary ammonium compounds and quaternary phosphonium compounds.

Abstract: A process for the in vitro production of chemically modified polyphenolic polymer (PPP). First, stable, highly active extracellular tyrosinase is produced from genetically transformed microorganism such as Streptomyces antibioticus. The tyrosinase is then incubated with a reaction substrate such as l-tyrosine, hydrolyzed protein, or an oligopeptide in combination with l-tyrosine. The ratio of the oligopeptide/tyrosine combination as well as variation in the concentration of tyrosinase can be used to modify the color, the molecular size, and the spectral absorbance properties of the PPP produced. Alternatively, or additionally, oxidants such as hydrogen peroxide or hypochlorite can be used to modify the color of the PPP, regardless of the method used to produce the PPP, and the PPP can subsequently be fractionated using molecular weight cut-off ultrafiltration. Organic solvents can also be used in the method of making PPP to produce PPPs having variable but reproducible physical properties.

Abstract: Novel cyclic imino ether compositions containing one or more mesogenic moieties, when polymerized, result in products having improved properties.

Abstract: A method for producing an aromatic poly(thio)ether ketone having repeating units of the following formula (II): ##STR1## wherein each of R.sup.1 to R.sup.12 is a hydrogen atom, a halogen atom, a hydrocarbon group or an alkoxy group, X is an oxygen atom or a sulfur atom, provided that part of X may be a direct bond, and n is an integer of from 0 to 2, which comprises reacting an aromatic (thio)ether carboxylic acid fluoride of the following formula (I): ##STR2## wherein R.sup.1 to R.sup.12, X and n are as defined above, under pressure in an aprotic organic solvent in the presence of boron trifluoride.

Abstract: A copolymer of an aromatic anhydride and an aliphatic ester suitable for use in surgical devices and a process for making said copolymer.

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: Laminar structures of PVF and substantially amorphous resin such as PEKK, backfilled with injection molding resin, exhibit an excellent combination of physical and aesthetic properties.

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: 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.

Abstract: Salts that contain AA-PBZ monomer ions and BB-PBZ monomer ions can be precipitated from an aqueous solution by contacting soluble salts of the monomers in an aqueous solution. The monomer salt can be polymerized by ordinary techniques to form polybenzazole polymers without the need for devolatilization and with very accurate stoichiometric control.

Abstract: Novel polyiminocarbonates having molecular weights exceeding 70,000 daltons. Novel solution polymerization and interfacial polymerization processes for the preparation of polyiminocarbonates in which cyanate compounds are reacted with diphenol compounds in the presence of a strong base catalyst.

Abstract: A process for preparing a polyetherimide-polyimide copolymer by (a) reacting a bis (ether anhydride) with a stoichiometric excess of an organic diamine in an inert, non-polar solvent to form an amine-terminated oligomer-solvent mixture; (b) removing unreacted organic diamine from the oligomer-solvent mixture; and (c) reacting the oligomer with an aromatic dianhydride.

Abstract: A pervaporation membrane may be an acid-resistant polybenzidimazole (PBI) membrane. The acid-resistant PBI membrane may be a PBI membrane chemically modified by a process selected from the group consisting of sulfonation, phosphonation, cross-linking, N-substitution, and/or combinations thereof. The membrane may be thermally stabilized. A method for the dehydration of an acid material may include the steps of: contacting an acidic aqueous solution with a membrane of an acid-resistant polybenzidimazole; taking away a permeate stream rich in water; and taking away a concentrate steam rich in the acid material. The acidic aqueous solution may be acetic acid.