Abstract: A process for preparing high strength carbon fiber from PAN-fiber wherein the time of the oxidation step is reduced from 30-90 minutes to about 8-15 minutes and product prepared therefrom.

Abstract: Disclosed herein is a fiber capable of basic gas absorption and easy regeneration. Disclosed also herein is a process for producing said fiber. The basic gas absorptive fiber is an acrylic fiber characterized by a specific amount of nitrogen which is increased by crosslinking with hydrazine, a specific amount of carboxyl groups and amido groups resulting from modification of nitrile groups, and a specific value of tensile strength. It is prepared from acrylic fiber by crosslinking with hydrazine and subsequent hydrolysis and conversion of hydroxyl groups into carboxylic acid. It has good processability and can be used repeatedly.

Abstract: Acrylic fiber with persistent antifungal properties can be prepared by extruding a dope which comprises an acrylic polymer in solution and an antifungal agent through a die into a coagulating bath. The antifungal agent is preferably a neutral organic compound of low solubility in water, for example tolnaftate. The antifungal agent is preferably dispersed in the fiber in the form of fine particles.

Abstract: This invention relates to a process for forming metal or non-metal carbide fiber from the corresponding metal or non-metal.

Abstract: A process for preparing PAN fibers under precipitation polymerization conditions in an aqueous solvent system.

Abstract: The efficiency of a redistribution catalyst during polycarbonate redistribution is improved by employing an extruder screw design that provides a melt seal between the extruder throat and the vacuum port. A melt seal exists when the free volume within the extruder is sufficiently filled with molten resin so as to prevent the passage of gases between sections of the extruder.

Abstract: A process for making acrylic fibers in which control of polymer composition and spin bath composition provide improved product properties.

Abstract: A process for the rapid precipitation polymerization of acrylonitrile and a minor amount of a vinyl carboxylic acid comonomer in an environment of less than 10 ppm metal-ions to produce an acrylonitrile copolymer which, when pyrolyzed in an oxidizing atmosphere, produces a high quality carbon fiber.

Abstract: A multi-layered conjugated acrylic fiber comprises different acrylic polymers which are conjugated along the fiber axis in layers. On the average the fiber contains more than two layers of acrylic polymers. The shrinkage forming ratio in boiling water of the conjugated acrylic fiber is 7-15% and the shrinkage forming stress is 5-20 mg/denier. To make the acrylic fiber water absorbent, one or more of the acrylic polymers may contain 0.3 to 2.0 mmole/g of carboxylic acid groups. The fibers may be made by introducing the polymers into a static mixer in such a way as to retain a number of separate layers of the polymers, and thence to a spinneret through a filter having a maximum mesh space of 10 or more. After spinning out the dope, it is drawn, washed and dried. Except where water-absorbent fiber is wanted, this is followed by shrinkage forming treatment and redrawing; the water-absorbent fiber is treated with alkali solution either in the form of yarn, or a fabric made therfrom.

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: A novel spinning apparatus is provided with a tubular coagulating liquid flow control valve body made of an elastomeric material and whose inner diameter is changeable according to external pressure. The valve body has a simple structure and is easy to retrofit to a conventional spinning apparatus. When dope is extruded, a mass of dope with gelled skin can pass easily and quickly through the opened valve body so that the spinning workability at the start of spinning is high. Further, since the coagulating liquid flows smoothly, the spinning speed can be increased without damaging the filaments.

Abstract: A graphite fiber having an elastic modulus E of 340-680 GPa, a microvoid radius of not larger than 20 .ANG. and a crystal size L.sub.c (.ANG.) satisfying the following formula:L.sub.c.sup.3 .ltoreq.0.918.times.10.sup.3 E-3.times.10.sup.5is valuable for a composite material having an improved compression strength. The graphite fiber is made preferably by oxidizing an acrylonitrile polymer precursor containing 0.05-8 wt. % of comonomer units and having an iodine adsorption amount of not larger than 3 wt. % and an orientation degree of at least 85%, at 200.degree.-300.degree. C. in an oxidative atmosphere under tension to obtain an oxidized fiber having a water adsorption of not larger than 7 wt. % and an orientation degree of at least 78%, followed by carbonization and graphitization of the oxidized fiber under tension.

Abstract: The present invention relates to a shaped material consisting of a layer having open microvoids (hereinafter referred to as light-scattering layer) and a layer having a hue different from that of the light-scattering layer (hereinafter referred to as color-developing layer), the light-scattering layer constituting at least part of the outer surface of the shaped material and the color-developing layer constituting the rest of the shaped material, which shaped material changes its color reversibly depending upon its moist or dry condition, as well as to a process for producing said shaped material.

Abstract: An acrylic fiber tow which includes 1) monocomponent filaments of each of two acrylonitrile polymers differing in hydrophilic properties, 2) bicomponent filaments of both of said polymers having one interface between polymers components and 3) bicomponent filaments of both of said polymers having more than one interface between polymer components. This fiber, however, in spite of its composition of numerous filaments of differing structure provides a tow bundle having a desirable level of reversible crimp measured in a manner specific to the type of crimp designated.

Abstract: The process for production of polyacrylonitrile hollow threads with a stable, asymmetric pore structure by a dry-wet-spinning process with glycerine-based core liquids, definite draw and after treatment conditions and a treatment with alcohols and drying.

Abstract: Carbon fiber precursors are stabilized regarding their mechanical properties by conducting the stabilization procedure in at least two steps, the first at a temperature at which the maximum plasticity of the polymer is attained while stretching the fiber 10-50% and the second at 200.degree.-300.degree. C., but higher than the first.

Abstract: A fiber or filament of a swellable polymer of high tensile strength is made by spinning a polymeric raw material which is produced by agitating a suspension of solid particles of an acrylonitrile polymer in dilute sulfuric acid having an acid concentration between 40 to 50 percent by weight until the polymer is hydrolyzed to an extent that it contains from 10 to 30 percent by weight of carboxyl groups such that sticking of individual particles of the polymer to one another is avoided.

Abstract: An acrylic multifilamentary material possessing an internal structure which is particularly suited for thermal conversion to high strength carbon fibers is formed via a specifically defined combination of processing conditions. The acrylic polymer while in substantially homogeneous admixture with appropriate concentrations (as defined) of acetonitrile and water is melt extruded and is drawn at a relatively low draw ratio which is substantially less than the maximum draw ratio achievable. This fibrous material which is capable of readily undergoing drawing is passed through a heat treatment zone wherein the evolution of residual acetonitrile and water takes place. The resulting fibrous material following such heat treatment is subjected to additional drawing to accomplish further orientation and internal structure modification and to produce a fibrous material of the appropriate denier for carbon fiber production.

Abstract: An acrylic multifilamentary material possessing an internal structure which is well suited for thermal conversion to high strength carbon fibers is formed via a specifically defined combination of processing conditions. The acrylic polymer while in substantially homogeneous admixture with appropriate concentrations (as defined) of C.sub.1 to C.sub.2 nitroalkane and water is melt extruded and is drawn at a relatively low draw ratio which is substantially less than the maximum draw ratio achievable. During the melt extrusion a C.sub.1 to C.sub.4 monohydroxy alkanol preferably also is present in the substantially homogenous admixture. The fibrous material which is capable of readily undergoing drawing next is passed through a heat treatment zone wherein the evolution of residual nitroalkane, monohydroxy alkanol and water takes place.

Abstract: In a method of manufacturing carbon fiber with less uniformity of physical strength in the longitudinal direction, an oil additive in a volatile medium is applied to an organic fiber after it is removed from a container and while the volatile medium has not completely evaporated from the fiber, and before the fiber is fed to a flameproofing furnace.

Abstract: A carbon fiber of high strength is disclosed, each filament of which is substantially circular in its cross-section but which has circumferential ruggedness which extends in parallel to an axis of the filament to form pleats. The ruggedness has a depth of more than 0.1 .mu.m.The carbon fiber is prepared by extruding a spinning solution of an aqueous polyacrylonitrile/pure zinc chloride solution of a specified polymer content into a coagulating bath at a specified draft ratio, followed by washing, drying and stretching at a total stretching ratio of 10-20 folds to form a precursor which is then subjected to conventional stabilizing and carbonizing steps.

Abstract: An acrylic multifilamentary material possessing an internal structure which is particularly suited for thermal conversion to high strength carbon fibers is formed via a specifically defined combination of processing conditions. The acrylic polymer while in substantially homogeneous admixture with appropriate concentrations (as defined) of acetonitrile, C.sub.1 to C.sub.4 monohydroxy alkanol, and water is melt extruded and is drawn at a relatively low draw ratio which is substantially less than the maximum draw ratio achievable. This fibrous material which is capable of readily undergoing drawing is passed through a heat treatment zone wherein the evolution of residual acetonitrile, the monohydroxy alkanol and water takes place. The resulting fibrous material following such heat treatment is subjected to additional drawing to accomplish further orientation and internal structure modification and to produce a fibrous material of the appropriate denier for carbon fiber production.

Abstract: A process of producing carbon fibers, which comprises oxidizing polyacrylonitrile filaments having a tensile strength at 240.degree. C. of 0.3 g/d or higher and a tensile modulus at 240.degree. C. of 2.0 g/d or higher in an oxidizing atmosphere under a high tension of 0.2 g/d or higher, and carbonizing the oxidized filaments under a high tension.

Abstract: An improvement in the conventional wet-spinning process for producing acrylic fibers increases the spinning performance and/or productivity of the process and comprises imparting a plurality of stretches to the fibers as they are being dried on the heat rolls of the drying train employed in the process.

Abstract: Polyacrylonitrile articles, such as filaments, tapes and films, having high tensile strength and modulus, and prepared by adding to a solution of polyacrilonitrile with a molecular weight above 3.times.10.sup.5, preferably above 5.times.10.sup.5, a minor amount of a bivalent metal compound, converting the solution into a solvent containing article, cooling this article to form a gel article, removing from this gel the solvent and metal compound, and stretching the resulting article at increased temperature. With this process filaments with a tensile strength above 1.2 GPa and a modulus above 16 GPa can be obtained.

Abstract: Ceramic alloys or solid solutions are formed by dispersing a powdery metal alloy or intimate mixture of two alloying metals in a precarbonaceous polymer such as polyacrylonitrile, forming the mixture into a molded article such as fibers, and heating the molded articles at a temperature and in a pyrolyzation atmosphere sufficient to carbonize the polymer and cause reaction of the metals with carbon and/or the pyrolyzation gas.

Abstract: A process for producing an acrylic fiber comprising the steps of:(a) dissolving a polymer having a weight-average molecular weight of at least 5.times.10.sup.5 and containing at least 80 wt. % acrylonitrile in a solvent comprising dimethylformamide or dimethylacetamide at a polymer concentration of 5-15 wt. % to provide a spinning solution having a viscosity of 500-1,500 poises at 45.degree. C.;(b) extruding the solution into a gaseous medium to form filaments;(c) introducing the filaments into a coagulation bath comprising water and at least one of dimethylformamide and dimethylacetamide at 0.degree. C. or below; and(d) stretching the coagulated filaments to a draw ratio of at least 3 to provide an acrylic fiber having at least 90% X-ray orientation and an X-ray crystallinity parameter of up to 1 degree. The resulting acrylic fiber has high strength and high modulus.

Abstract: A process for producing preoxidized fibers, which comprises preoxidizing acrylic fibers having a fluorine-containing surface active agent and at least one phosphoric surface active agent selected from the group consisting of compounds represented by the following formulae (I), (II) and (III), and preoxidizing the acrylic fibers thus-obtained: ##STR1## wherein R.sub.1 represents an aliphatic hydrocarbon group having 1 to 17 carbon atoms, R.sub.2, R.sub.3 and R.sub.4, which may be the same or different, and each represents a hydrogen atom, a lower alkyl group, a hydroxyethyl group or a hydroxyisopropyl group, ##STR2## wherein R.sub.5, R.sub.6 and R.sub.7, which may be the same or different, each represents a hydrogen atom or a hydroxyethyl group.

Abstract: Polyacrylonitrile (PAN) fibers are prepared by forming a 2-15 weight % solution of PAN of M.sub.w at least 500,000, extruding, cooling to below the gel temperature, extracting and drying. At least one of the gel fiber, the fiber containing extraction solvent and the dried gel is stretched. The product PAN fibers have a M.sub.w at least 500,000 (e.g. 1,000,000-4,000,000 or 1,500,000-2,500,000), a tenacity at least 5 g/den (e.g., at least 7 g/den) and a secant modulus at least 100 g/den (e.g. at least 125 g/den).

Abstract: A method for manufacturing carbon fiber strand from an acrylic polymer by steps of (a) wet spinning, (b) washing with water to obtain gelled fiber strand and (c) drying, wherein during the drying step the gelled fiber strand is shrunk by about 5 to 15% when the water of the gelled fiber strand is within a range of from about 100 to 20% by weight based on the weight of the dry fiber strand. An acrylic fiber strand without coalescence or entangling of filaments can consistently be obtained, from which carbon fibers with high quality and substantially no coalescence can be produced.

Abstract: A method for producing a composite hollow fiber membrane by coating a porous hollow fiber substrate with a dilute solution of a membrane-forming composition containing a membrane-forming material and a solvent therefor by contacting the porous hollow fiber substrate with the composition, partially evaporating some of the solvent from the coated porous hollow fiber substrate, contacting the partially dried coating porous hollow fiber substrate with a coagulant and recovering the composite hollow fiber membrane. Also included are the composite hollow fiber membranes so produced and their use as permeable membranes for separating at least one fluid from at least one other fluid in a fluid mixture.

Abstract: A spinning solution of an acrylonitrile polymer is subjected to dry-wet spinning through an annular type spinneret having a non-perforated part, i.e. a part not formed with spinning orifices, extending from the outer periphery to the inner periphery. The spinneret has more than 3,000 spinning orifices, at the perforated part of the annular portion. The extruded fibers are then passed through a coagulation bath, and the coagulated fibers are then stretched. By this method, uniform acrylic fibers can be produced without causing quality unevenness and fiber defects due to uneven coagulation, filament agglutination, and fluctuation of the gap between spinneret lower surface and liquid surface of the coagulation bath.

Abstract: Processes for producing semipermeable membranes in the form of hollow fibers are disclosed including extruding a solution of a block copolymer including at least one hydrophilic polymer and at least one hydrophobic polymer while simultaneously injecting a gaseous or vaporous center medium into the center bore of the hollow fiber extrudate, including coagulating the extrudate so formed therefrom. The preferred process includes using air or the components of air as the center medium and employing a polyethyleneoxide-polycarbonate block copolymer to form the hollow fiber membranes.

Abstract: Hydrophilic polyacrylonitrile filaments or fibres where at least one filament-forming synthetic polymer is wet spun in a spinning solvent and wherein the spinning solvent has added to it from 10 to 20% by weight of a substance which is readily miscible with the spinning solvent and a washing liquid and is a nonsolvent for the polymer to be spun.

Abstract: Mixtures of water with water-miscible solvent(s) containing suspended, emulsified and/or colloidal impurities are purified by contacting the water-solvent mixture with an at least partially open celled foam containing 1-75 weight percent active pulverulent additives. The liquid and solid phases are then separated. The active pulverulent additives which may be incorporated into the foam by means of a binder or by incorporation in the reactants used to form the foam include active coals, brown coal dust, peat, iron oxides and brown coal coke dust.

Abstract: Silica-containing acrylic and modacrylic fibres are obtained without spinning defects in that an aqueous silica sol is reacted with a silane and with a polar organic solvent, the sequence in which the two agents are added being optional, the water is distilled off in a vacuum at a temperature of at most 60.degree. C., the thread-forming polymer is then added in a quantity which is sufficient to form a spinnable solution and the solution is spun.

Abstract: Monofils and bristles which comprise at least 90% by weight of acrylonitrile units and have a linear density of more than 2.5 tex possess a relative solution viscosity of 1.7 to 6.0, a tear strength of at least 20 cN/tex and an initial modulus of more than 700 cN/tex.The manufacturing process is distinguished by a wet stretch of the spun filaments by at least 1:4, drying under tension and a subsequent hot stretch of at least 1:2, the overall stretch being at least 1:8, preferably 1:10 to 1:20.The monofils and bristles according to the invention are suitable in particular for producing filament-reinforced composite materials.

Abstract: A conductive fiber is made by an electroless plating process which is used in conjunction with a wet spinning process. The polymer must be catalyzed before the wet gel is collapsed. The resulting filament has a conductive region which is at least partially coincident with the polymer structure.

Abstract: This invention relates to a method of producing a flame-retardant acrylic polymer by polymerizing, in the presence of a radical polymerization initiator, a vinyl monomer containing acrylonitrile in an amount of more than 75 weight %, in an aqueous medium in which is present a halogen-containing polymer latex substantially free from an emulsifier. The acrylic polymer can provide flame-retardant shaped products, especially fibers, which have no problems in the operation of spinning, transparency, gloss, dyed color clearness, etc.

Abstract: An acrylic fiber precursor for high performance carbon fibers free of defects which comprises an acrylonitrile polymer containing at least 90% by weight of acrylonitrile and has a surface roughness of 2.0 to 3.0 with dense inner structure. from a solution comprising 24 to 27.5% of the acrylonitrile polymer is dry-jet wet spun into a coagulation bath consisting essentially of dimethylformamide or dimethylacetamide and having a bath temperature of 5.degree. to 25.degree. C.Carbon fibers obtained by carbonizing these precursor acrylic fibers have no fusion bonding or agglutination of filaments and exhibit high performance.

Abstract: Threads and fibres of synthetic polymers containing from 0.1 to 5% by weight, based on the polymer, of one or more than one compound corresponding to the formula (I) ##STR1## wherein R represents hydrogen or alkyl,R.sup.1 represents halogen, hydroxyl, optionally substituted alkyl, optionally substituted alkoxy, optionally substituted phenoxy, a group --S(O).sub.p -alkyl which is optionally substituted in the alkyl portion, nitro, optionally substituted amino or a condensed carbocyclic or heterocyclic group,p stands for the numerical value 0, 1 or 2,R.sup.2 represents halogen, alkyl which is optionally substituted, alkoxy, alkylmercapto, nitro, cyano, carboxylic acid amide or a condensed carbocyclic group,m represents an integer from 0 to 5,n represents an integer from 0 to 4, the substituents being either identical or different when m and/or n has a value greater than 1, and X, Y and Z are identical or different and represent a nitrogen atom, the group .dbd.CH-- or ##STR2## where R.sup.

Abstract: Polyacrylonitrile (PAN) fiber of high strength (tensile strength.gtoreq.20 g/d) produced from a polymer composed mainly of acrylonitrile (AN) and having a weight average molecular weight not less than 400,000, and a method of producing said fiber characterized by a multistage stretching step and a drying step under particular conditions.

Abstract: The present invention discloses a flame-retardant acrylic synthetic fiber comprising acrylonitrile and a vinyl monomer copolymerizable therewith and containing a finely divided inorganic tin compound. The fiber has high flame retardancy, outstanding gloss and transparency, and satisfactory whiteness and dyeability.

Abstract: The invention relates to a process for the production of swellable filaments, fibers and shaped structures of acrylic polymer, by reacting the free carboxyl groups of the filament-forming substance with substances which react in a basic manner, with water being excluded, and to swellable filaments and fibers thus obtained, which, in the dry state, have tensile strengths of more than 10 cN/tex and knot strengths of more than 6 cN/tex and which can be further processed by means of the customary textile machinery.

Abstract: The invention is concerned with a method of producing in-line dyed fibers, in a gel state, characterized in that it essentially consists of extruding the spinning dope in a coagulum bath, stretching the resulting filaments, scrubbing said filaments to remove residual solvent, passing the resulting filament tow through a dyeing bath at an overall rate in excess of 4 cm.sup.3 bath per second per square centimeter of tow surface area. The overall rate, being preferably in the 4 to 10 cm.sup.3 /sec per cm.sup.2 range, is achieved by means of crossflows to the forward advance direction of said tow, and alternately directed to and from said tow, the tow residence time in the dyeing bath being no longer than 5 seconds. The tow is then subjected to a dye fixing heat treatment, and is then scrubbed, finished, and dried. The method is particularly suitable for use with substantially acrylic and modacrylic fibers.

Abstract: The invention relates to filaments and fibers spun from at least 98% by weight of polyacrylonitrile and relative viscosities of between 2.5 and 6.0 which have tensile strengths of more than 50 cN/tex with an elongation at break of at most 15% and a shrinkage at the boil of less than 5% and to a process for their production which comprises at least 2 stretching stages with a minimum stretching ratio of 1:9 as well as a concluding setting stage in which the filaments are treated without shrinkage in dry heat at 170.degree. to 280.degree. C.Such filaments and fibers are distinguished by an increased resistance to swelling and hydrolysis and they are particularly suitable for reinforcing organic and inorganic materials.

Abstract: Equally biaxially oriented film is produced by extruding liquified polymer in tubular form, orienting the tubular film in the radial direction only and then either (1) equally orienting the radially oriented film in the longitudinal direction and drying the resultant equally biaxially oriented film while preventing any shrinkage thereof or (2) orienting the radially oriented film in the longitudinal direction to a degree less than said radial orientation but equal to the radial orientation remaining after the biaxially oriented film undergoes radial shrinkage upon drying thereof in the absence of radial shrinkage control and drying the resultant biaxially oriented film in the absence of radial shrinkage control.

Abstract: The invention relates to continuous processes for preparing dimethylformamide-insoluble acrylic filaments and fibers which incur a weight loss of at most 20, preferably 15% on being heated up to 400.degree. C., by spinning appropriate polymer solutions, treating the filament bundles obtained before the first drying or heating stage in a continuous manner with an aqueous solution containing copper(I) ions, thermally fixing the copper content, and heating the bundles to 200.degree. to 350.degree. C.

Abstract: A hydrophilic, water-absorbing acrylonitrile polymer fiber is obtained when the fiber is structured from a hydrophilic acrylonitrile polymer so as to contain a water-hiding cavity and to have a filament denier in the range of about 0.75-2.0.

Abstract: The present invention provides an industrial process for producing acrylic fibers having non-circular cross-sections which are excellent in gloss, softness, etc. In this process, which is a wet-spinning method using an inorganic solvent, a particular acrylonitrile polymer solution is spun through a spinnerette having circular spinning orifices. The steps of spinning, coagulation, water-washing and wet-heat stretching are carried out in integral combination and under specific conditions.