US3671411A - Treatment of carbon or graphite fibers and yarns for use in fiber reinforced composites - Google Patents

Treatment of carbon or graphite fibers and yarns for use in fiber reinforced composites Download PDF

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Publication number
US3671411A
US3671411A US16251A US3671411DA US3671411A US 3671411 A US3671411 A US 3671411A US 16251 A US16251 A US 16251A US 3671411D A US3671411D A US 3671411DA US 3671411 A US3671411 A US 3671411A
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United States
Prior art keywords
fiber
electrolyte
carbon
range
graphite
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Expired - Lifetime
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US16251A
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English (en)
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James D Ray
Samuel Steingiser
Robert A Cass
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United States Department of the Air Force
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United States Department of the Air Force
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    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F11/00—Chemical after-treatment of artificial filaments or the like during manufacture
    • D01F11/10—Chemical after-treatment of artificial filaments or the like during manufacture of carbon
    • D01F11/16—Chemical after-treatment of artificial filaments or the like during manufacture of carbon by physicochemical methods

Definitions

  • Carbon fiber or yarn as used in fiber reinforced composites is electrolytically treated to improve the surface characteristics and thereby to improve its bonding or adhesion to the matrix material. By this improved bonding, shear strengths of resultant fiber resin or plastic composites have been more than doubled.
  • the electrolytic treatment is conducted by using the fiber or yarn as the anode and using en electrolyte such as an aqueous caustic solution.
  • This invention relates to carbon or graphite fiber or yarn reinforcing materials. In one aspect it relates to the treatment of the reinforcing fibers or yarns to improve the adhesion between the fiber surface and a matrix material.
  • High strength and high modulus carbon fibers and yarns particularly those composed essentially of graphite and generally referred to as graphite fibers and yarns, have already been used as reinforcing agents in composite materials for aerospace structures.
  • the bonding of resins or plastics to the carbon fibers in such composites has not been entirely satisfactory, and, as a result, the shear strengths of the resultant composites have been less than desired.
  • the present invention resides in a process whereby the bonding properties of carbon and graphite fibers or yarns are improved to a surprising extent, in the improved fibers per se, and in the compositions incorporating the fibers.
  • the process comprises the step of subjecting a carbon or graphite fiber to an electrolytic reaction in an aqueous electrolyte whereby negative ions are attracted to the surface of the fiber acting as an anode, thereby modifying the fiber surface.
  • subsequent bonding to plastics and resins is improved to such an extent that the shear strengths are increased in many cases to more than double the values obtained without this particular pretreatment with little or no loss in tensile strength.
  • nascent oxygen forms at the anode and oxidizes the fiber surface.
  • the improvement obtained by the present process results from the uniformity of the fiber surface oxidation and the accuracy with which the degree of oxidation can be controlled.
  • hydroxyl groups and carboxyl groups also become attached to the surface and contribute to a marked extent to the improvement in bonding properties.
  • any electrolyte which will generate nascent oxygen at the anode can be used in the practice of this invention.
  • suitable electrolytes include aqueous solutions of sodium hydroxide, potassium hydroxide, phosphoric acid, nitric acid, sulfuric acid, and the like. It is usually preferred to employ aqueous sodium hydroxide or aqueous phosphoric acid solutions. It is to be understood that the concentration of the solutions will have an efiect on the rate of generation of nascent oxygen. For a practical rate of generation, it has been found to be advantageous to use as the electrolyte a solution having a concentration of 0.5 to 20, preferably 1 to ID, weight percent.
  • the carbon fiber or yarn is used as the anode as stated, and the cathode can be an electrode of graphite or other carbon form, or can be any metal or other material suitable for cathode purposes.
  • the process can be applied either as a batch or continuous operation. In the latter case, a continuous carbon fiber or yarn is passed over or under rolls to guide the fiber through the solution, and connection with the current source is applied to the fiber either through one of the rolls in contact with the fiber, or by any other convenient means.
  • the length, thickness or other dimensions of the fibers are not critical and are determined by other considerations in the ultimate purpose for which the product is to be used.
  • the temperature used is not critical except as it may affect the rate of nascent oxygen reaction with the fiber surface. However, in such cases, slower rates of reaction can be compensated for by prolonged treatment. Therefore, whatever temperature is convenient, such as 2050C., is found to be most practical.
  • any current density can be employed which is sufficient to produce nascent oxygen at the anode in an amount great enough to modify the surface of the fiber so as to improve the bonding properties of the fiber.
  • a current density in the approximate range of 0.0005 to 0.005 ampere per square centimeter (amp/cm") of the surface area of the yarn or fiber to be treated has been found to be satisfactory. It is usually preferred to employ a current density in the range of about 0.001 to 0.003 amp/cm?
  • Any convenient voltage can be used in the electrolysis that will give the desired current density. It is generally preferred to utilize a voltage between about 10 and volts.
  • the period of the electrolytic reaction usually ranges from about 25 to 500 seconds, preferably from about 75 to 250 seconds.
  • the temperature of the electrolyte can conveniently range from about 20 to 50C.
  • the improvement in adhesion properties or bonding properties of the fibers of this invention occurs with any type of resin with which the fiber is mixed. Improvements in shear strengths occur for carbon fiber composites in which the resin components include phenolic resins, epoxy resins, polyester resins, polyimide resins, polyamide resins as well as elastomers such as natural rubber, polybutadienes, polyisoprenes, butadiene-styrene copolymers, polyurethanes, and plastics such as polyethylene, polypropylene, and the like.
  • the composite generally contains in the range of about 25 to 75 volume percent of the treated carbon fibers.
  • EXAMPLE I Several samples of commercial graphite yarn were taken from the same bobbin so as to have yarn as identical as possible for use in conducting comparative tests.
  • the graphite yarn used in this and succeeding examples was composed of two plies, each ply consisting of 720 filaments.
  • the yarn denier per ply was 351 (g/9,000 m).
  • the filament surface area was 1 square meter per gram.
  • the electrolytic tests were conducted in a bath containing percent aqueous sodium hydroxide solution as the electrolyte and maintained at C.
  • the cathode was a carbon electrode supported horizontally near the bottom of the tank and connected to a direct current source.
  • the respective samples of yarn were submerged in theelectrolyte by passing them individually under two rollers supported completely submerged in the bath.
  • the positive pole of the direct current source was connected to the continuous yarn being fed into the bath by means of a graphite contact roll over which the yarn was passed prior to its entry into the electrolyte bath. In each run the dwell or residence time of the yarn in the bath was 150 seconds.
  • the graphite yarn had a specific gravity of 1.85 g./cc.
  • each yarn was used as the reinforcement in a laminate prepared with an epoxy resin having a specific gravity of 1.21 g./cc.
  • the particular epoxy resin used was a commercially available product which was supplied as a twopackage system, one containing a mixture of bis-diglycidol ether of bisphenol A and bis-2,3-epoxycyclopentyl ether and the other meta-phenylenediamine (hardening agent).
  • the composite was cured at C for 2 hours and 150C for 4 hours at a pressure of approximately psi.
  • the shear test results are an average of fourdifferent tests made on each sample.
  • EXAMPLE 1 EXAMPLE 111 A series of comparative tests was made, following the 45 A series of experiments was conducted using the procedure procedure of example 1 and using a number of strands of graphite yarn all from a different bobbin from that used in example 1. In preparing the resin composite, the proportion was adjusted to 60 volume percent fiber. The axes of the fibers in the of example 1 and varying the current density. The properties of the treated fibers and the resin-fiber composites are reported in table 111. In each run the dwell or residence of the yarn in the electrolyte bath was 150 seconds.
  • EXAMPLE V The procedure of example 1 was repeated with similar results using a 5 percent aqueous phosphoric acid solution instead of the sodium hydroxide solution. Improvements also occur when aqueous solutions of nitric acid, boric acid or sulfuric acid are used as the electrolyte.
  • the strand of yarn was impregnated with a liquid matrix resin to hold the plies in place. Any excess resin was wiped off after which the strand was placed in an oven at 150C. for minutes. At least one plastic bead was then threaded onto each end of the strand, The beads were fastened in place on the resin by injecting adhesive inside the hole in the bead. The adhesive was cured by heating at 100C for 30 minutes. Each end of the strand was then placed in a holding device having a Breaking load, lbs.
  • a process for improving the bonding properties of a carbon or graphite fiber to a resin or plastic matrix which comprises the steps of subjecting a carbon or graphite fiber to an electrolytic reaction for a period in the range of about 25 to 500 seconds whereby negative ions of an aqueous electrolyte with which said fiber is in contact are attracted to said fiber acting as an anode and nascent oxygen is produced at the surface of said fiber, thereby modifying the fiber surface; and controlling current density used in the electrolytic reaction so that it is in the range of about 0.0005 to 0.005 ampere per square centimeter of surface area of said fiber in contact with said electrolyte.
  • said electrolyte is an aqueous solution of a compound selected from the group consisting of sodium hydroxide, potassium hydroxide, phosphoric acid, nitric acid, boric acid and sulfuric acid and the concentration of said compound in said solution is in the range of about 0.5 to 20 weight percent.
  • a process for improving the bonding properties of a carbon or graphite fiber to a resin or plastic matrix which comprises passing a continuous strand of said fiber through a bath containing an aqueous electrolyte, said electrolyte having an electrode immersed therein and connected to a negative pole of a direct current source and said strand prior to entry into said bath passing over a graphite roller connected to a positive pole of said direct current source; controlling the speed at which said strand is passed through the electrolyte so that it is in contact therewith and subjected to an electrolytic reaction for a period in the range of about 25 to 500 seconds whereby negative ions of the electrolyte are attracted to said fiber and nascent oxygen is produced at its surface, thereby modifying the fiber surface; and controlling current density used in the electrolytic reaction so that it is in the range of about 0.0005 to 0.005 ampere per square centimeter of surface area of the fiber in contact with said electrolyte.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Chemical Or Physical Treatment Of Fibers (AREA)
  • Reinforced Plastic Materials (AREA)
US16251A 1970-03-03 1970-03-03 Treatment of carbon or graphite fibers and yarns for use in fiber reinforced composites Expired - Lifetime US3671411A (en)

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US1625170A 1970-03-03 1970-03-03

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US (1) US3671411A (enrdf_load_stackoverflow)
JP (1) JPS544438B1 (enrdf_load_stackoverflow)
DE (1) DE2110193A1 (enrdf_load_stackoverflow)
FR (1) FR2084126A5 (enrdf_load_stackoverflow)

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3859187A (en) * 1972-09-25 1975-01-07 Celanese Corp Electrolytic process for the surface modification of high modulus carbon fibers
US3865705A (en) * 1972-04-21 1975-02-11 Rhone Progil Process for modifying the surface characteristics of carbon substrates and composite articles produced from the treated substrates
US4050997A (en) * 1972-12-18 1977-09-27 Maschinenfabrik Augsburg-Nurnberg Aktiengesellschaft Method of manufacturing a fiber reinforced composite material
US4234398A (en) * 1978-04-12 1980-11-18 Toray Industries, Inc. Carbon fiber surface treatment
FR2477593A1 (fr) * 1980-03-05 1981-09-11 Toho Beslon Co Procede de traitement de surface de fibres de carbone et fibres ainsi obtenues
US4474906A (en) * 1982-01-22 1984-10-02 Toho Beslon Co., Ltd. Carbon fiber and resin composition reinforced by the same
US4495039A (en) * 1981-08-07 1985-01-22 Sorin Biomedica S.P.A. Method for activating a pyrocarbon electrode tip
US4609449A (en) * 1982-03-16 1986-09-02 American Cyanamid Company Apparatus for the production of continuous yarns or tows comprising high strength metal coated fibers
US4639297A (en) * 1983-03-16 1987-01-27 Asahi Kasei Kogyo Kabushiki Kaisha Fluorinated graphites and a process for production thereof
US4704196A (en) * 1985-08-20 1987-11-03 Toa Nenryo Kogyo Kabushiki Kaisha Process for surface treatment of carbon fiber
EP0251491A1 (en) * 1986-05-30 1988-01-07 Amoco Corporation Multi-electrolyte treatment of carbon fibres to modify shear resistance
US4814157A (en) * 1986-02-07 1989-03-21 Mitsubishi Rayon Co., Ltd. Carbon fibers and method for producing same
WO1991003057A1 (en) * 1989-08-14 1991-03-07 Hyperion Catalysis International, Inc. Resin compound
WO1991001621A3 (en) * 1989-07-27 1991-06-27 Hyperion Catalysis Int Composites and methods for making same
WO1994005049A1 (en) * 1992-08-13 1994-03-03 H Power Corporation Hydrogen power cell
US5611964A (en) * 1984-12-06 1997-03-18 Hyperion Catalysis International Fibril filled molding compositions
US6464908B1 (en) 1988-01-28 2002-10-15 Hyperion Catalysis International, Inc. Method of molding composites containing carbon fibrils
US20090092831A1 (en) * 2006-04-28 2009-04-09 Toho Tenax Europe Gmbh Carbon Fiber
CN100515329C (zh) * 2007-11-27 2009-07-22 扬州大学 纳米碳电极的一种制备方法
US20100304171A1 (en) * 2009-06-02 2010-12-02 Integran Technologies, Inc. Metal-clad polymer article
US20100304063A1 (en) * 2009-06-02 2010-12-02 Integran Technologies, Inc. Metal-coated polymer article of high durability and vacuum and/or pressure integrity
US20100300889A1 (en) * 2009-06-02 2010-12-02 Integran Technologies, Inc Anodically assisted chemical etching of conductive polymers and polymer composites
US20100304065A1 (en) * 2009-06-02 2010-12-02 Integran Technologies, Inc. Metal-clad polymer article
US9004240B2 (en) 2013-02-27 2015-04-14 Integran Technologies Inc. Friction liner
US9340677B2 (en) 2012-02-01 2016-05-17 Ut-Battelle, Llc Apparatus and process for the surface treatment of carbon fibers
CN116856162A (zh) * 2023-07-14 2023-10-10 中复神鹰碳纤维股份有限公司 一种碳纤维、复合材料及碳纤维表面处理方法

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4600572A (en) * 1984-06-22 1986-07-15 Toray Industries, Inc. Ultrahigh strength carbon fibers
FR2703080B1 (fr) * 1993-03-26 1995-06-16 Lyon Ecole Centrale Procede d'implantation de sites de fixation covalente sur un substrat en fibre de cartone et capteur enzymatique comprenant un element conducteur de mesure susceptible d'etre obtenu, notamment, par ce procede.

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2807577A (en) * 1956-04-25 1957-09-24 Cabot Godfrey L Inc Electrolytic after treatment of carbon black
US3323869A (en) * 1963-12-19 1967-06-06 Dow Chemical Co Process for producing expanded graphite

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1257022A (enrdf_load_stackoverflow) * 1968-01-03 1971-12-15

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2807577A (en) * 1956-04-25 1957-09-24 Cabot Godfrey L Inc Electrolytic after treatment of carbon black
US3323869A (en) * 1963-12-19 1967-06-06 Dow Chemical Co Process for producing expanded graphite

Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3865705A (en) * 1972-04-21 1975-02-11 Rhone Progil Process for modifying the surface characteristics of carbon substrates and composite articles produced from the treated substrates
US3859187A (en) * 1972-09-25 1975-01-07 Celanese Corp Electrolytic process for the surface modification of high modulus carbon fibers
US4050997A (en) * 1972-12-18 1977-09-27 Maschinenfabrik Augsburg-Nurnberg Aktiengesellschaft Method of manufacturing a fiber reinforced composite material
US4234398A (en) * 1978-04-12 1980-11-18 Toray Industries, Inc. Carbon fiber surface treatment
FR2477593A1 (fr) * 1980-03-05 1981-09-11 Toho Beslon Co Procede de traitement de surface de fibres de carbone et fibres ainsi obtenues
US4401533A (en) * 1980-03-05 1983-08-30 Toho Belson Co., Ltd. Surface-treatment of carbon fiber
US4495039A (en) * 1981-08-07 1985-01-22 Sorin Biomedica S.P.A. Method for activating a pyrocarbon electrode tip
US4474906A (en) * 1982-01-22 1984-10-02 Toho Beslon Co., Ltd. Carbon fiber and resin composition reinforced by the same
US4609449A (en) * 1982-03-16 1986-09-02 American Cyanamid Company Apparatus for the production of continuous yarns or tows comprising high strength metal coated fibers
US4639297A (en) * 1983-03-16 1987-01-27 Asahi Kasei Kogyo Kabushiki Kaisha Fluorinated graphites and a process for production thereof
US5611964A (en) * 1984-12-06 1997-03-18 Hyperion Catalysis International Fibril filled molding compositions
US4704196A (en) * 1985-08-20 1987-11-03 Toa Nenryo Kogyo Kabushiki Kaisha Process for surface treatment of carbon fiber
US4814157A (en) * 1986-02-07 1989-03-21 Mitsubishi Rayon Co., Ltd. Carbon fibers and method for producing same
EP0251491A1 (en) * 1986-05-30 1988-01-07 Amoco Corporation Multi-electrolyte treatment of carbon fibres to modify shear resistance
US6464908B1 (en) 1988-01-28 2002-10-15 Hyperion Catalysis International, Inc. Method of molding composites containing carbon fibrils
WO1991001621A3 (en) * 1989-07-27 1991-06-27 Hyperion Catalysis Int Composites and methods for making same
WO1991003057A1 (en) * 1989-08-14 1991-03-07 Hyperion Catalysis International, Inc. Resin compound
WO1994005049A1 (en) * 1992-08-13 1994-03-03 H Power Corporation Hydrogen power cell
US20090092831A1 (en) * 2006-04-28 2009-04-09 Toho Tenax Europe Gmbh Carbon Fiber
US8834997B2 (en) * 2006-04-28 2014-09-16 Toho Tenax Europe Gmbh Carbon fiber
CN100515329C (zh) * 2007-11-27 2009-07-22 扬州大学 纳米碳电极的一种制备方法
US8394507B2 (en) 2009-06-02 2013-03-12 Integran Technologies, Inc. Metal-clad polymer article
US8741392B2 (en) 2009-06-02 2014-06-03 Integran Technologies, Inc. Anodically assisted chemical etching of conductive polymers and polymer composites
US20100304065A1 (en) * 2009-06-02 2010-12-02 Integran Technologies, Inc. Metal-clad polymer article
WO2010139051A1 (en) * 2009-06-02 2010-12-09 Integran Technologies, Inc. Anodically assisted chemical etching of conductive polymers and polymer composites
US8247050B2 (en) 2009-06-02 2012-08-21 Integran Technologies, Inc. Metal-coated polymer article of high durability and vacuum and/or pressure integrity
US8394473B2 (en) 2009-06-02 2013-03-12 Integran Technologies, Inc. Metal-coated polymer article of high durability and vacuum and/or pressure integrity
US20100304063A1 (en) * 2009-06-02 2010-12-02 Integran Technologies, Inc. Metal-coated polymer article of high durability and vacuum and/or pressure integrity
US20100300889A1 (en) * 2009-06-02 2010-12-02 Integran Technologies, Inc Anodically assisted chemical etching of conductive polymers and polymer composites
US20100304171A1 (en) * 2009-06-02 2010-12-02 Integran Technologies, Inc. Metal-clad polymer article
US8906515B2 (en) 2009-06-02 2014-12-09 Integran Technologies, Inc. Metal-clad polymer article
US8911878B2 (en) 2009-06-02 2014-12-16 Integran Technologies Inc. Structural metal-clad polymer article
US8916248B2 (en) 2009-06-02 2014-12-23 Integran Technologies, Inc. Metal-coated polymer article
US9340677B2 (en) 2012-02-01 2016-05-17 Ut-Battelle, Llc Apparatus and process for the surface treatment of carbon fibers
US9004240B2 (en) 2013-02-27 2015-04-14 Integran Technologies Inc. Friction liner
CN116856162A (zh) * 2023-07-14 2023-10-10 中复神鹰碳纤维股份有限公司 一种碳纤维、复合材料及碳纤维表面处理方法

Also Published As

Publication number Publication date
JPS544438B1 (enrdf_load_stackoverflow) 1979-03-06
FR2084126A5 (enrdf_load_stackoverflow) 1971-12-17
DE2110193A1 (de) 1971-10-21

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