Welcome to Vince Kelly's Carbon Fiber website

You can golf, ride, sail, tennis, drive, cycle, decorate or even
FLY CARBON FIBER !

Dozens of new applications for carbon fiber are being developed annually
With world production of PAN based carbon fiber set to double in 5 years,
we are happy to provide this resource for your use. Enjoy!

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The clock is ticking!


Download a PowerPoint presentation about carbon fiber properties and costs
PAN carbon Fiber data
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My name is Vince Kelly , I hope to provide you with information about carbon fiber, a unique material, used in a wealth of applications, all over the world.

The Carbon Atom


Carbon fibers are derived from one of two precursor materials

PITCH or PAN

PAN (Polyacrylonitrile fibers)

PITCH based carbon fibers have lower mechanical properties and are therfore rarely used in critical structural applications.PAN based carbon fibers are under continual development and are used in composites to make materials of great strength and lightness

The raw material of PAN, acrylonitrile (AN), is a product of the chemical industry and can be manufactured as follows:

Acrylonitrile (AN) is used as a raw material in acrylic fibers, ABS resin, AS resin, synthetic rubber (NBR), acrylamide and other materials. Global production capacity is 4.67 million tons, approximately 60% of which is consumed for acrylic fibers. In the early manufacturing processes acetylene and hydrogen cyanide (HCN) were used as a raw material, whereas today nearly all AN is manufactured using what is called the Sohio process, whereby an ammoxidation reaction are applied from inexpensive propylene and ammonia. Technological advances, particularly surrounding research into improved catalysts for the Sohio process, are proceeding, promoted by a concern for energy conservation and lessening the environmental loading. The research aims include improved productivity, reduced byproducts, and lesser wastewater and waste gas.

2. Sohio process
The Sohio process was perfected in 1960 by The Standard Oil Co. of Ohio, owing to the development of an epoch-making catalyst that synthesizes AN in a single-stage reaction using propylene and ammonia. The reaction took place using the fluid-bed od. The P-Mo-Bi group is used as the catalyst and favorable fluidized conditions are maintained by adjusting the physical properties of the catalyst.

The reaction gas contains not only AN, but also acetonitrile, hydrogen cyanide and other byproduct gasses, so AN products are obtained by having the reaction gas absorbed into water, then using evaporation separation.

5. Improved processes
The Sohio process was epoch-making at the time it was developed, but improvements have been made in response to the following conditions:
(1)The AN yield of approximately 60% was not very high.
(2)The process circulated and used large amounts of water, requiring a lot of energy.
(3)Approximately 1.5 tons to 2 tons of wastewater was generated for every ton of AN produced.
(4) Treatment technology for the waste gas was incomplete.

I. Improved catalyst

II. Steam reduction
Monsanto Corp. improved the water extractive distillation stage of the Sohio process, reducing the amount of steam required to produce one ton of AN by three tons.

III. Wastewater and waste gas treatment
AN wastewater normally contains ammonium sulfate, along with small amounts of nitrile compounds, hydrocyanic acid and compounds with a high boiling point. Alkali used to be added to the wastewater before discharging, but nowadays wet oxidation processes and biological treatment processes are being employed. Bayer Inc. has developed the technology to recover high-grade ammonium sulfate from the gas generated as a byproduct of the reaction.

Polymerisation of acrylonitrile produces PAN, the most common carbon fiber feedstock

The basic unit of PAN is:

The Manufacturing Process

The conversion of PAN to carbon fibers is normally made in 4 continuous stages

  • Oxidation
  • Carbonisation(Graphitisation)
  • Surface treatment
  • Sizing
  • OXIDATION involves heating the fibers to around 300 deg C in air. This evolves hydrogen from the fibers and adds less volatile oxygen.

    The polymer changes from a ladder to a stable ring structure, and the fiber changes colour from white though brown to black.

    The resulting material is a textile fiber which is fireproof, some companies actually sell this as an end product for example SGL Technic (Scotland), under the tradename PANOX. (OXidised PAN)

    CARBONISATION(GRAPHITISATION) involves heating the fibers up to 3000 � C in an inert atmosphere, the fibers are now nearly 100 % carbon.

    The temperature will determine the grade of fiber produced:

    Typical Commercial Carbon Fiber Properties
    Figures courtesy of Toray


    SURFACE TREATMENT forms chemical bonds to the carbon surface, to give a better cohesion to the resin system of the composite

    SIZING is a neutral finishing agent (usually epoxy) to protect the fibers during further processing (eg prepregging) and to act as an interface to the resin system of the composite

    Where are carbon fibers used ?

    24K carbon fiber spool, before converson to composites

    Carbon fibers are used primarily in composites, these are structures containing two or more components, in the case of fiber reinforced composites this is the fiber and a resin. A composite containing two types of fiber, eg. carbon and glass, is known as a hybrid composite structure. The origins of textile reinforced composites are linked to the development of glass fibers, which commenced in 1938 by the Owens Corning Fiberglass Corporation (USA). Original large scale applications included air filtration, thermal and electrical insulation and the reinforcement of plastics. As the technology of textile reinforced composites expanded, a growing demand from the aerospace industry for composite materials with superior properties emeged. In particular, materials with (1) higher specific strength, (2) higher specific moduli and (3) low density were required. Other desirable properties are good fatigue resistance, and dimensional stability. Carbon fibers were developed to meet this demand.

    Carbon fibers are usually mixed with resin to form a "Pre-Preg"
    (Pre-impregnated)sheet, wound between release paper

    A filming line used in the production of carbon fiber prepreg at SP Systems


    above photos courtesy of SP Sytems

    
    

    Comparison of Carbon Fiber and Steel

    Material Tensile Strength (GPa) Tensile Modulus (GPa) Density (g/ccm) Specific Strength (GPa) Specific Modulus (GPa)
    High Strength Carbon Fiber (T700) 4.9 230.0 1.75 2.80 130
    Intermediate Modulus Carbon Fiber (T800) 5.49 294.0 1.81 3.03 162
    High Tensile Steel 1.3 210.0 7.87 0.17 27

    The superior properties of carbon fiber to steel and other metals meant that the aerospace industry was an obvious market for composite materials, the use of lighter materials in aircraft construction allows for fuel savings or a greater payload, Carbon fibers are used extensively in both military and civil aircraft structures. As the technology of producing composites advanced, other fibers were developed to supply this market. For example Aramid and E-Glass, see how they compare to carbon fibers:

    
    

    Comparison of Fiber Reinforcements

    Material Tensile Strength (GPa) Tensile Modulus (GPa) Density (g/ccm) Specific Strength (GPa) Specific Modulus (GPa)
    High Strength Carbon fiber (T700) 4.9 230.0 1.75 2.80 130
    Kevlar 3.6 60.0 1.44 2.50 42
    E Glass 3.4 22.0 2.60 1.31 8

    Carbon fibers are also unique in the range of properties that can be found, in this one generic type of material. As most carbon fiber manufactures are working in a state of constant development and improvement, the range of fibers now available to the structural engineer is always changing, look at the developments of the last 15 years:


    Carbon fibers are found in the intereiors of nearly all new aircraft


    And increasingly in more critical parts of the aircraft

    The author of this page has been active in carbon fibers since 1980. My name is Vince Kelly, I was born in Manchester England, my work in carbon fibers has taken me to 1986 in Scotland, from 1986 to 2000 in Germany. I am currently an international consultant in all aspects of carbon fiber technology. I am also a professional member of the Society for the Advancement of Material and Process Engineering SAMPE. Founded in 1944, SAMPE is an international not-for-profit professional Organization with approximately 5000 members worldwide. As the premier technical Society in the fields of advanced materials and process engineering technology, SAMPE is recognized for its strengths across numerous industries and markets. The Society holds annual conferences and exhibitions in the USA, Europe and Japan and publishes two widely recognized journals throughout the year. Professional and Student Chapters actively hold local meetings, regional workshops and seminars.

    Email:vince@carbon-fiber.com


              

    Download a video of Moses Lake carbon fiber plant, USA
    Including processing of the fiber for automotive application
    Moses Lake CF Plant
    (.wmv format)