Abstract: A process for making a transparent film comprising a liquid crystalline polymer, and a transparent film made thereby having high barrier properties. In this process, the LCP is dissolved in an appropriate solvent, then cast into a film at ambient or near-ambient temperatures. The film optionally may be dried at elevated temperatures and/or reduced pressures to remove the solvent. The film is then annealed at a temperature between the glass transition temperature (T.sub.g) and the melting point temperature (T.sub.m) of the polymer. The result is a highly transparent film having liquid crystalline morphology and high barrier properties.

Abstract: A novel miscible blend of component polymers comprised of from about 5 weight percent to about 95 weight percent of a polybenzimidazole and from about 95 weight percent to about 5 weight percent of an aromatic polyamide, aromatic polyamide-hydrazide or aromatic polyamide containing heterocyclic linkages. Miscibility of the component polymers of the blend is indicated by infrared, X-Ray and Differential Scanning Calorimetry analyses and scanning electron photomicrographs. In a film or molded article of a blend mostly comprised of a polybenzimidazole, it is preferred that the aromatic polyamide, aromatic polyamide-hydrazide or aromatic polyamide containing heterocyclic linkages be present in the blend in an amount sufficient to result in a blend with improved tensile properties compared to the polybenzimidazole and that is more thermally processable than the polybenzimidazole.

Abstract: A process for enhancing the thermo-oxidation stability of a polybenzimidazole-containing article wherein the article contains from about 5 to about 100 weight percent of polybenzimidazole and from about 0 to about 95 weight percent of a thermoplastic polymer, by the steps of providing a phosphoric acid solution of about 2.0 to about 10.0 weight percent of acid; contacting the polybenzimidazole-containing article with the acid solution for sufficient time to produce an acid-treated article; drying the acid-treated article at a low temperature to remove excess acid; and heat treating the dried article at a temperature ranging from about 400.degree. to about 500.degree. C. in an inert atmosphere to form a phosphate barrier layer on the surface of the article, wherein the article retains at least about 50 percent of its weight after isothermal aging at about 600.degree. F. for a period of at least about 300 hours.

Abstract: A method of making controlled sequence condensation copolymers from mer systems capable of forming at least two unique recurring units is disclosed and claimed. Sequenced polyesters containing the residue of hydroxyacids are specifically exemplified.

Abstract: Fibers and fibrets of a novel miscible blend of component polymers comprising from about 5 weight percent to about 95 weight percent of a polybenzimidazole and from about 95 weight percent to about 5 weight percent of an aromatic polyamide, aromatic polyamide-hydrazide or aromatic polyamide containing heterocyclic linkages. Miscibility of the component polymers of the blend is indicated by infrared, X-Ray and Differential Scanning Calorimetry analyses and electron photomicrographs. In fibers or fibrets of a blend mostly comprised of a polybenzimidazole, it is preferred that the aromatic polyamide, aromatic polyamide-hydrazide or aromatic polyamide containing heterocyclic linkages be present in the blend in an amount sufficient to yield a blend with improved tensile properties compared to the polybenzimidazole and more thermally processable than the polybenzimidazole. The fibers or fibrets of the blend have a lower moisture regain than polybenzimidazole fibers or fibrets.

Abstract: A process is disclosed for the production of biaxially oriented liquid crystal films. The process includes:(i) forming an anisotropic dope from a polymerization solution of rigid rod heterocyclic liquid crystalline polymers such as poly{[benzo(1,2-d:4,5-d')bisthiazole-2,6-diyl] 1,4-phenylene}, its cis isomer or mixtures thereof, and poly{[benzo(1,2-d:4,5-d')bisoxazole-2,6-diyl] 1,4-phenylene}, its cis isomer or mixtures thereof, and a solvent such as polyphosphoric acid;(ii) extruding the dope to form a film;(iii) imparting biaxial orientation to the film to increase the transverse strength thereof;(iv) solidifying the biaxially oriented film; and(v) washing the solidified film to remove the solvent. Also disclosed is a liquid crystal film produced by the above process.

Abstract: Shaped articles are prepared from rigid rod heterocyclic liquid crystalline polymers. The articles are prepared by polymerizing the polymer in a reaction medium whereby a solution of the polymer is formed and by forming the articles directly from the polymer solution.

Abstract: The properties of shaped articles of poly {[benzo(1,2-d:4,5-d')bisthiazole-2,6-diyl]-1,4-phenylene}, its cis isomer and mixtures thereof are improved by a process of heat treatment under tension. The articles may be prepared from a dope obtained by dissolving the formed polymer in an appropriate solvent or by forming the polymer under conditions which enable the article to be prepared directly from the reaction medium.

Abstract: A film of poly{[benzo(1,2-d:4,5-d')bisthiazole-2,6-diyl]-1,4-phenylene}, its cis isomer or mixtures thereof is formed by extruding a solution of the polymer on a casting roll which is rotating to yield a surface speed slightly greater than the rate of extrusion. The solution of the polymer may be prepared by dissolving the polymer in an appropriate solvent or by reacting the monomers in a selected reaction medium. The cast film is washed, subjected to an elevated temperature, preferably heat treated under tension, and recovered.

Abstract: An improved solution of a polybenzimidazole suitable for use in the formation of shaped articles (e.g. fibers, films, and the like) is provided which includes a minor amount of an organo-lithium compound (as defined) which has been found to be capable of inhibiting the separation of the solution into phases of greater and lesser concentrations of the polybenzimidazole upon the passage of time. In a preferred embodiment the organo-lithium compound is lithium stearate. Not only is stability imparted to the solution prior to the formation of a shaped article, but the potential for catastrophic corrosive stress cracking of stainless steel equipment in contact with the solution is eliminated such as that which may occur following the extended use of the common prior art additive, lithium chloride.

Abstract: An improved overall process is provided wherein poly(bisbenzimidazobenzophenanthroline) is formed on an expeditious basis and is recovered from the reaction mass in substantially pure form. Appropriate quantities of 1,4,5,8-tetracarboxy naphthalene dianhydride and 3,3',4,4' -tetraaminobiphenyl are condensed as defined) in a reaction zone while dissolved in molten antimony trichloride, and the resulting reaction mass containing the dissolved product is discharged into a precipitation zone containing hydrochloric acid (as defined). The resulting solid product is separated and dried. The liquid portion which is separated from the solid product contains antimony trichloride dissolved in hydrochloric acid and is subjected to distillation which substantially separates these components. The antimony trichloride is recycled to the reaction zone, and the hydrochloric acid is recycled to the precipitation zone.