Abstract: The present invention relates to a process for forming a foamed elastomeric polymer. The process involves forming a reverse emulsion of liquid droplets in a continuous liquid phase of polymer precursor and then polymerizing the precursor to entrap uniformly distributed droplets of the liquid in pores formed in the polymer bulk. The liquid in the pores is then removed under supercritical conditions.

Abstract: A polymeric dope solution comprising a polymeric material and a mixed solvent as a solvent system for use in the preparation of an integrally skinned asymmetric membrane having a surface layer (selective surface layer) and a porous support layer, which is useful as a gas separation membrane, is disclosed. Also disclosed are a process for the preparation of the asymmetric membrane using the polymeric dope solution, and an integrally skinned dope solution prepared thereby.The asymmetric membranes according to the present invention show good gas permeability and high permselectivity.

Abstract: Foams capable of absorbing blood and blood-based fluids, especially menses. These absorbent foams have high capillary absorption pressures required of absorbents used in catamenial products, yet have sufficient openness to allow free movement of the insoluble components in blood-based fluids such as menses. These absorbent foams are made by polymerizing high internal phase emulsions (HIPEs) where the volume to weight ratio of the water phase to the oil phase is in the range of from about 20:1 to about 125:1. These foams are particularly useful as absorbent members for catamenial pads.

Abstract: A method of producing a microporous polyolefin membrane having a relatively large pore size and a high permeability, the membrane being suitable for use in water treatment, microfiltration, etc. The method comprises dissolving a polyolefin composition in a solvent to prepare a solution, extruding the solution through a die lip into a form of gel-like sheet, rapidly cooling the gel-like sheet, removing a residual solvent in the cooled sheet by a washing solvent, and drying the resultant sheet to remove the washing solvent. The polyolefin composition is a mixture of (A) an ultra high molecular weight polyolefin having a weight average molecular weight of 5.times.10.sup.5 or more and (B) a polyolefin having a weight average molecular weight less than 5.times.10.sup.5, and a weight ratio of (B)/(A) is 0.2 to 20.

Abstract: Absorbent foams materials that are capable of acquiring and distributing aqueous fluids, especially discharged body fluids such as urine. These absorbent foams combine relatively high capillary absorption pressures and capacity-per-weight properties that allow them to acquire fluid, with or without the aid of gravity. These absorbent foams also give up this fluid efficiently to higher absorption pressure storage materials, including foam-based absorbent fluid storage components, without collapsing. These absorbent foams are made by polymerizing high internal phase emulsions (HIPEs).

Abstract: The present invention relates to compressable polymeric foam materials useful as insulation. These polymeric foams are prepared by polymerization of certain water-in-oil emulsions having a relatively high ratio of water phase to oil phase, commonly known as "HIPEs." The polymeric foam materials comprise a generally hydrophobic, flexible or semi-flexible, nonionic polymeric foam structure of interconnected open-cells. The foam structures have:(a) a specific surface area per foam volume of at least about 0.01 m.sup.2 /cc;(b) an expanded density of less than about 0.05 g/cc; and(c) a ratio of expanded to compressed thickness of at least about 3:1;wherein when the foam is compressed to 33% of its original expanded thickness and is thereafter maintained without artificial restraint on its surface, said foam will reexpand by no more than 50% after 21 days at ambient temperature (22.degree. C.).

Abstract: Provided are organic aerogel foams and their method of manufacture from polyfunctional vinyl monomers, such as trimethylolpropane trimethacrylate and/or ethoxylated trimethyol trimethacrylate, which foams are ideally suited for filtering media, and especially for microorganism filtration for capture of bacteria, viruses, yeast and other microparticles.

Abstract: Biodegradable and/or compostable polymers are made from isoprene, 2,3-dimethyl-1,3-butadiene or like conjugated dienes and a crosslinking agent having a cleavable linking group such as ethylene glycol dimethacrylate. These polymers can be used to make absorbent foams that are useful in absorbent articles such as diapers, as well as other biodegradable articles such as films, and latexes useful as binders and adhesives.

Abstract: Absorbent foam materials that are capable of acquiring and distributing aqueous fluids, especially discharged body fluids such as urine. These absorbent foams combine relatively high capillary absorption pressures and capacity-per-weight properties that allow them to acquire fluid, with or without the aid of gravity. These absorbent foams also give up this fluid efficiently to higher absorption pressure storage materials, including foam-based absorbent fluid storage components, without collapsing. These absorbent foams are made by polymerizing high internal phase emulsions (HIPEs).

Abstract: The present invention relates to a high-strength porous film or sheet consisting essentially of a high-molecular-weight polyethylene resin having a viscosity-average molecular weight of not less than 300,000, wherein the said film has a thickness of 5 to 50 .mu.m, an air permeability of 200 to 1,000 sec/100 cc, a porosity of 10 to 50% and a pin puncture strength of not less than 600 gf/25 .mu.m, and a process for producing the said film.

Abstract: The present invention relates to porous crosslinked polymeric microbeads having cavities joined by interconnecting pores wherein at least some of the cavities at the interior of each microbead communicate with the surface of the microbead. The present invention also relates to a process for producing a porous, crosslinked polymeric microbead as well as the product of this process. This process involves combining an oil phase with an aqueous discontinuous phase to form an emulsion, adding the emulsion to an aqueous suspension medium to form an oil-in-water suspension of dispersed emulsion droplets, and polymerizing the emulsion droplets to form microbeads. At least 10% of the microbeads produced in accordance with the present invention are substantially spherical or substantially ellipsoidal or a combination of the two.

Abstract: The present invention relates to an electronic device for distributing electrical signals between electronic elements comprising a dielectric foamed thermoset polymer having a plurality of electrical circuits.

Abstract: The disclosure is a liquid absorbable material comprising a porous formed article possessed of partitioning walls of a cross-linked polymer and continued micropores, characterized in that said material has a density in the range of 0.2 to 1.0 g/cm.sup.3, and (a) that said partitioning walls exhibit a swelling degree to kerosine in the range of 2 to 10, and that said material has an absorption capacity per unit volume, the capacity being at least 4 cm.sup.3 /cm.sup.3 for water, ethanol, toluene and kerosine, respectively, or (b) that said material has an absorption capacity per unit weight, the capacity being at least 10 g/g for water, ethanol, toluene and kerosine, respectively, the liquids being at a temperature not less than the softening point of the cross-linked polymer. The liquid absorbable material can absorb liquids such as water and petroleum quickly and expand with the absorbed liquid.

Abstract: Low density collapsed absorbent foams materials that, upon contact with aqueous fluids, in particular urine, can expand and absorb these fluids. These low density foams typically have an expanded thickness from about 6 to about 10 times the thickness of the foams in their collapsed state. These low density foams are made by polymerizing high internal phase emulsions (HIPEs) where the volume to weight ratio of the water phase to the oil phase is in the range of from about 55:1 to about 100:1.

Abstract: Low density collapsed absorbent foams materials that, upon contact with aqueous fluids, in particular urine, can expand and absorb these fluids. These low density foams typically have an expanded thickness from about 6 to about 10 times the thickness of the foams in their collapsed state. These low density foams are made by polymerizing high internal phase emulsions (HIPEs) where the volume to weight ratio of the water phase to the oil phase is in the range of from about 55:1 to about 100:1.

Abstract: The invention relates to the use of polymeric foam materials for insulation. These polymeric foams are prepared by polymerization of certain water-in-oil emulsions having a relatively high ratio of water phase to oil phase, commonly known in the art as high internal phase emulstions, or "HIPEs." The HIPE-derived foam materials used in the present invention comprise a generally hydrophobic, flexible, semi-flexible, or rigid nonionic polymeric foam structure of interconnected open-cells. These foam structures have:A) a specific surface area per foam volume of at least about 0.01 m.sup.2 /cc;B) a density of less than about 0.05 g/cc; andC) a glass transition temperature (Tg) of between about -20.degree. and 90.degree. C.The foams can be used as thermal, acoustic, and/or mechanical insulation materials.In a preferred embodiment, the foams used can be prepared, packaged, and shipped in a compressed, high density state and will "spring back" upon activation (e.g. heat) to the original density of the foam.

Abstract: The present invention relates to a process for forming a foamed elastomeric polymer. The process involves forming a reverse emulsion of liquid droplets in a continuous liquid phase of polymer precursor and then polymerizing the precursor to entrap uniformly distributed droplets of the liquid in pores formed in the polymer bulk. The liquid in the pores is then removed under supercritical conditions.

Abstract: An alkanol permeation polymer membrane prepared by dissolving biocompatible, non-allergenic polymer capable of being dissolved in polar organic solvent in methylene chloride to prepare a first solution, dissolving cellulose or glycol type polyol compounds in cosolvent composed of alkanol and methylene chloride to prepare a second solution, and mixing the first solution with the second solution, casting the mixed solution on a glass plate with a controlled thickness and evaporating may control the release of drugs effectively.

Abstract: Scaffold bodies and methods for their fabrication are disclosed, and, more particularly, fabrication of scaffold bodies by freeze-drying emulsion of polymer solutions are disclosed.

Abstract: This invention relates to porous polyfluoroethylene (PTFE), shaped articles prepared therefrom, and to methods of preparing said articles.

Abstract: A polymeric reticulated structure is prepared by mixing an ethylene-propylene copolymer having an ethylene content of at least 60% by weight or a thermoplastic block copolymer terminated with a crystalline ethylene block with a low molecular weight material. The low molecular weight material is trapped in the three-dimensional continuous network the copolymer forms.

Abstract: Condensation polymerization followed by a supercritical extraction step can be used to obtain highly cross-linked nanoporous polymers with high surface area, controlled pore sizes and rigid structural integrity. The invention polymers are useful for applications requiring separation membranes.

Abstract: The present invention describes a method for preparing an asymmetric porous membrane by a dry-wet phase inversion method, which comprises contacting a cast or spun polymer solution with water or organic vapor prior to immersing into the non-solvent precipitation medium, whereby said water or organic vapor is adsorbed onto the cast or spun polymer solution. Higher permeability and excellent rejection ability can be obtained, due to the high porosity and uniform pore size of said membranes according to the present invention.

Abstract: Process for the preparation of aerogels by subcritical drying of inorganic and organic hydrogels and lyogels to give aerogels, dielectric drying methods being used.

Abstract: A novel processing technique is reported to bond non-woven fibers and, thus, prepare structural interconnecting fiber networks with different shapes for organ implants. The fibers are physically joined without any surface or bulk modification and have their initial diameter.

Abstract: Absorbent foam materials that are capable of acquiring and distributing aqueous fluids, especially discharged body fluids such as urine. These absorbent foams combine relatively high capillary absorption pressures and capacity-per-weight properties that allow them to acquire fluid, with or without the aid of gravity. These absorbent foams also give up this fluid efficiently to higher absorption pressure storage materials, including foam-based absorbent fluid storage components, without collapsing. These absorbent foams are made by polymerizing high internal phase emulsions (HIPEs).

Abstract: Biaxially oriented films from high molecular weight polyethylene are characterized by a gas permeable structure formed from random-arranged microfibrils. The films have coefficients of static friction and kinetic friction of not more than 1.0. The biaxially oriented films are further characterized by service smoothness as well as tensile (tangent) modulus and tensile strength. The films may be used for lamination, filter, or for packaging for moisture absorbers. The biaxially oriented films may be obtained by extracting a hydrocarbon plasticizer from a sheet formed from the high molecular weight polyethylene and a hydrocarbon plasticizer, stretching the resulting sheet to obtain an oriented film having a specific surface area of at least 70 m.sup.2 /g and a fibril structure, and heating the oriented film under a standard length constraint to reduce the oriented film in specific area by at least 20 m.sup.2 /g.

Abstract: A method of preparing near net shape, monolithic, porous SiC foams is disclosed. Organosilicon precursors are used to produce polymeric gels by thermally induced phase separation, wherein, a sufficiently concentrated solution of an organosilicon polymer is cooled below its solidification temperature to form a gel. Following solvent removal from the gel, the polymer foam is pretreated in an oxygen plasma in order to raise its glass transition temperature. The pretreated foam is then pyrolized in an inert atmosphere to form a SiC foam.

Abstract: A syntactic foam-core material and method for its production are disclosed wherein glass microspheres and chopped fiberglass are dispersed within a slurry comprised of a suitable resin such as an epoxy and a suitable solvent such as methyl ethyl ketone. Under carefully controlled vacuum and rate of addition conditions, the microspheres and chopped fiberglass are added to the slurry to form a light weight syntactic foam-core material. The material may either be stored under cold conditions for use at a later time or it may be shaped and/or molded to conform to a desired configuration which, for example, may correspond with a desired component part. After curing, the material may be machined to final dimensions.

Abstract: Relatively thin, collapsed, i.e. unexpanded, polymeric foam materials that, upon contact with aqueous body fluids, expand and absorb such fluids, are disclosed. A process for consistently obtaining such relatively thin, collapsed polymeric foam materials by polymerizing a specific type of water-in-oil emulsion, commonly known as High Internal Phase Emulsions or "HIPE", is also disclosed.

Abstract: Low density collapsed absorbent foams materials that, upon contact with aqueous fluids, in particular urine, can expand and absorb these fluids. These low density foams typically have an expanded thickness from about 6 to about 10 times the thickness of the foams in their collapsed state. These low density foams are made by polymerizing high internal phase emulsions (HIPEs) where the volume to weight ratio of the water phase to the oil phase is in the range of from about 55:1 to about 100:1.

Abstract: A process is provided for the production of a porous crosslinked polymeric foam comprising the steps of: (a) providing a first water-in-oil emulsion comprising (i) a first mixture of polymerizable monomers comprising at least one oil-soluble vinyl monomer and from about 2 to about 70 weight percent, based on the mixture, of a multifunctional unsaturated crosslinking monomer, (ii) at least 70 weight percent, based on the emulsion, of water as the internal phase (iii) an effective amount to produce the water-in-oil emulsion of a first surfactant, and (iv) a first polymerization initiator; (b) providing a second water-in-oil emulsion comprising (i) a mixture of polymerizable monomers comprising at least one oil-soluble vinyl monomer and from about 2 to about 70 weight percent, based on the mixture, of a second multifunctional unsaturated crosslinking monomer, (ii) at least 70 weight percent, based on the emulsion, of water as the internal phase (iii) an effective amount to produce the water-in-oil emulsion of a

Abstract: Absorbent foams materials that are capable of acquiring and distributing aqueous fluids, especially discharged body fluids such as urine. These absorbent foams combine relatively high capillary absorption pressures and capacity-per-weight properties that allow them to acquire fluid, with or without the aid of gravity. These absorbent foams also give up this fluid efficiently to higher absorption pressure storage materials, including foam-based absorbent fluid storage components, without collapsing. These absorbent foams are made by polymerizing high internal phase emulsions (HIPEs).

Abstract: The invention relates to the use of polymeric foam materials for insulation. These polymeric foams are prepared by polymerization of certain water-in-oil emulsions having a relatively high ratio of water phase to oil phase, commonly known in the art as high internal phase emulstions, or "HIPEs." The HIPE-derived foam materials used in the present invention comprise a generally hydrophobic, flexible, semi-flexible, or rigid nonionic polymeric foam structure of interconnected open-cells. These foam structures have:A) a specific surface area per foam volume of at least about 0.01 m.sup.2 /cc;B) a density of less than about 0.05 g/cc; andC) a glass transition temperature (Tg) of between about -20.degree. and 90.degree. C.The foams can be used as thermal, acoustic, and/or mechanical insulation materials.In a preferred embodiment, the foams used can be prepared, packaged, and shipped in a compressed, high density state and will "spring back" upon activation (e.g. heat) to the original density of the foam.

Abstract: Condensation polymerization followed by a supercritical extraction step can be used to obtain highly cross-linked nanoporous polymers with high surface area, controlled pore sizes and rigid structural integrity. The invention polymers are useful for applications requiring separation membranes.

Abstract: A process for producing a water-absorbing resin, which comprises polymerizing (D) an aqueous solution comprising (A) at least one monomer component selected from the group consisting of an unsaturated carboxylic acid and salts thereof; (B) a compound having two or more unsaturated groups in a molecule; and (C) a compound having two or more functional groups which are capable of reacting with carboxyl groups in a molecule, the polymerization being conducted in such a manner that the following conditions (a) to (c) are simultaneously satisfied: (a) the molar ratio (B)/(C) being in the range of from 2.times.10.sup.-3 to 300, (b) the polymerization being initiated by a redox polymerization initiator, and (c) the maximum reaction temperature being in the range of from 60.degree. to 100.degree. C, and a water-absorbing resin having a degree of reduction in absorption magnification of from 1 to 16, and n absorption magnification under pressure of from 20 to 40.

Abstract: A molded structure 1 produced by extrusion, such as an expanded plastic foam, a sheet, a profile or the like, contains at least 10% by volume of open cells 2, 4 which have a polyhedron-like shape and are adjacent to one another. A higher temperature during the extrusion in comparison with the extrusion of thermoplastic molded structures having a closed-cell structure results in deformation-free opening of the cells. Webs 3 of cell walls 5, 6 remain intact in shape whether they have orifices 7 or no passages, so that the mechanical strength of the cell skeleton or of the space matrix is retained.

Abstract: Disclosed are methods of producing super absorbing polymeric networks of polyaspartates from crosslinked polysuccinimide. In one preferred method aspect, polysuccinimide is first reacted with an organic crosslinking agent, preferably an organic base containing at least two primary amine groups to form crosslinked polysuccinimide. The crosslinked polysuccinimide is then hydrolyzed to a polymeric network of polyaspartate which demonstrates super absorbing capability in water and in saline solution. Alternative method aspects are disclosed in which super absorbing polymeric networks of polyaspartates are produced in a single reaction vessel by sequentially crosslinking polysuccinimide with organic crosslinking agent in an aqueous reaction mixture and then hydrolyzing the reaction product to produce a polymeric network of polyaspartate.

Abstract: Disclosed is a method for obtaining composite material comprising a network of cross-linked polymer and fluid molecules. Such materials, using molecules of liquid crystal, are notably used in display screens. The originality of the disclosure lies in the drying, in supercritical phase, of the molecules that have enabled the preparation of the network. Generally, the operation of evaporation drying of the solvent leads to a deterioration of the network structure. With the method according to the invention, the network keeps its initial structure, making it possible to obtain high performance characteristics in scattering of light. Application to display screens and protection for detectors.No abstract figure.

Abstract: Process of mixing a fugitive plasticizer, e.g., ethylene carbonate, with moist particulate polyacrylonitrile then removing the water enabling adjustment of the melt viscosity for extrusion of the polyacrylonitrile into film, fiber, pellets and shaped articles. Stretching and heating the extruded polyacrylonitrile film or fiber causes the fugitive plasticizer to exude and vaporize from the film or fiber, carrying with it any remaining acrylonitrile monomer. The resulting film or fiber exhibits substantially increased molecular weight, thus enhancing the tensile strength and barrier properties of the polyacrylonitrile product. The process also produces polyacrylonitrile foam products. A novel cross-linking agent for polyacrylonitrile, divinyloxybutane, is disclosed. Thermostabilizing agents for polyacrylonitrile, N-maleimides and stilbene derivatives, are also disclosed.

Abstract: The present invention relates to porous crosslinked polymeric microbeads having cavities joined by interconnecting pores wherein at least some of the cavities at the interior of each microbead communicate with the surface of the microbead. Approximately 10% of the microbeads of the present invention are substantially spherical or substantially ellipsoid or a combination of the two. The present invention also relates to a process for producing a porous, crosslinked polymeric microbead as well as the product of this process. This process involves combining a continuous phase with an aqueous discontinuous phase to form an emulsion, adding the emulsion to an aqueous suspension medium to form an oil-in-water suspension of dispersed emulsion droplets, and polymerizing the emulsion droplets to form microbeads. Also included in the invention are modifications of the microbeads as well as methods for using the microbeads in a variety of applications.

Abstract: A one-step emulsification process for preparing aqueous suspensions of hollow, acrylate polymer microspheres conducted in the presence of at least one acid that is not free radically polymerizable. Surprisingly, the use of such an acid eliminates the previous requirement of using a polar copolymerizable monomer in the one-step emulsification process. The hollow acrylate polymer microspheres prepared from the process of the invention may be tacky or tack-free.

Abstract: An absorbent, microporous foam comprising a crosslinked polymer having interconnected fluid cells distributed throughout its mass, wherein the fluid cells have a diameter of between about 0.1 and about 100 .mu.m, and wherein the foam can rapidly absorb at least about twice its dry weight in fluid, is disclosed.A method for producing a microporous, absorbent foam is also disclosed. This method comprises the steps of:(a) mixing a cross-linkable polymer and a first solvent to form a stable solution, wherein the stable solution can be induced to phase separate;(b) inducing the stable solution to phase separate into a polymer-concentrated phase and a polymer-dilute phase after a predetermined period of time;(c) inducing crosslinking of said polymer, so that the polymer will crosslink in said concentrated phase for a predetermined period of time during phase separation to thereby form a microporous material; and(d) drying the microporous material to produce the absorbent foam.

Abstract: Absorbent foam materials that are capable of acquiring and distributing aqueous fluids, especially discharged body fluids such as urine. These absorbent foams combine relatively high capillary absorption pressures and capacity-per-weight properties that allow them to acquire fluid, with or without the aid of gravity. These absorbent foams also give up this fluid efficiently to higher absorption pressure storage materials, including foam-based absorbent fluid storage components, without collapsing. These absorbent foams are made by polymerizing high internal phase emulsions (HIPEs).

Abstract: N-Methylol derivatives of polycondensation products containing quaternary N atoms obtained fromA) basic ureas of the formulaHN(R.sup.1)--C--N(R.sup.2)--X.sup.1 --N(R.sup.3, R.sup.4) (I),B) polyamines of the formula(R.sup.6, R.sup.7)N--X.sup.2 --N(R.sup.8, R.sup.9) (II)andC) bifunctional alkylating agents,in whichX.sup.1, X.sup.2 and R.sup.1 -R.sup.9 have the meanings given in the description, are new. They are used as agents for improving the wet fastness properties of dyeings on cellulose and cellulose blend fabrics.

Abstract: Absorbent foams materials that are capable of acquiring and distributing aqueous fluids, especially discharged body fluids such as urine. These absorbent foams combine relatively high capillary absorption pressures and capacity-per-weight properties that allow them to acquire fluid, with or without the aid of gravity. These absorbent foams also give up this fluid efficiently to higher absorption pressure storage materials, including foam-based absorbent fluid storage components, without collapsing. These absorbent foams are made by polymerizing high internal phase emulsions (HIPEs).

Abstract: The disclosure is a liquid absorbable material comprising a porous formed article possessed of partitioning walls of a cross-linked polymer and continued micropores, characterized in that said material has a density in the range of 0.2 to 1.0 g/cm.sup.3, and (a) that said partitioning walls exhibit a swelling degree to kerosine in the range of 2 to 10, and that said material has an absorption capacity per unit volume, the capacity being at least 4 cm.sup.3 /cm.sup.3 for water, ethanol, toluene and kerosine, respectively, or (b) that said material has an absorption capacity per unit weight, the capacity being at least 10 g/g for water, ethanol, toluene and kerosine, respectively, the liquids being at a temperature not less than the softening point of the cross-linked polymer. The liquid absorbable material can absorb liquids such as water and petroleum quickly and expand with the absorbed liquid.

Abstract: The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes .ltoreq.1000.ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

Abstract: Absorbent foam materials that are capable of acquiring and distributing aqueous fluids, especially discharged body fluids such as urine. These absorbent foams combine relatively high capillary absorption pressures and capacity-per-weight properties that allow them to acquire fluid, with or without the aid of gravity. These absorbent foams also give up this fluid efficiently to higher absorption pressure storage materials, including foam-based absorbent fluid storage components, without collapsing. These absorbent foams are made by polymerizing high internal phase emulsions (HIPEs).

Abstract: Described is a continuous process for removing polyphosphoric acid from a polybenzazole dope filament, which comprises: (a) contacting the dope filament with water or a mixture of water and polyphosphoric acid under conditions sufficient to reduce the phosphorous content of the filament to less than about 10,000 ppm by weight; and then (b) contacting the dope filament with an aqueous solution of an inorganic base under conditions sufficient to convert at least about 50 percent of the polyphosphoric acid groups present in the filament to a salt of the base and the acid. It has been discovered that contacting the dope filament with a solution of a base after washing the filament to remove most of the residual phosphorous advantageously leads to an improvement in the initial tensile strength of the filament, as well as improved retention of tensile strength and/or molecular weight (of the polybenzazole polymer) following exposure to light and/or high temperatures.