How has the united States Always been at the Forefront of Carbon Fiber Technology?

 

Fiber was born in the United States, and its basic scientific research on high performance also started there. Today, the United States is still the world’s leading producer and user of high-performance carbon fiber. Studying the development of high-performance carbon fiber technology in the United States should be used as a reference for the technological progress and healthy development of my country’s carbon fiber industry.

 

This article reviews the early development of high-performance carbon fiber technology in the United States and the important research contributions of two scientists, and analyzes their experience.

 

Carbon Fiber was Born in the United States, Starting with the Invention of Incandescent lamps

 

Carbon fiber was born as the luminous body of incandescent lamps. Sir Joseph Wilson Swan (1828–1914), a British chemist and physicist, invented an incandescent lamp with platinum wire as the luminous body. To solve the problem of heat resistance of platinum wire, Swan used carbonized thin paper strips instead of platinum wire. Since carbon paper strips are easy to burn in the air, Swan basically solved this problem by evacuating the bulb into a vacuum.

 

In 1860, Swan invented a semi-vacuum electric lamp with carbon paper strips as the luminous body, which was the prototype of the incandescent lamp; but the vacuum technology was not mature at that time, so the lamp life was not long. In the late 1870s, vacuum technology had matured, and Swan invented a more practical incandescent lamp, which was patented in 1878.

 

In 1879, Thomas Alva Edison (1847-1931) invented an incandescent lamp with carbon fiber as the light source. He shaped the inner bark of linden, jute, Manila hemp and hemp, which are rich in natural linear polymers, into the required size and shape, and baked them at high temperature; when heated, these cellulose fibers composed of continuous glucose units were carbonized into carbon fibers.

 

In 1892, Edison’s “Manufacturing of Filamentsfor Incandescent Electric Lamp” was awarded a US patent (patent number: 470925) (Figure 1). It can be said that Edison invented the earliest commercialized carbon fiber.

 

Since the raw materials come from natural fibers, early carbon fibers had almost no structural strength and were easily broken and fractured during use. Even as a light source for incandescent lamps, their durability was not ideal.

 

Around 1910, tungsten filaments replaced early carbon fiber filaments. Despite this, many US patents have confirmed that research on improving the performance of carbon fiber has never stopped in the more than 30 years since Edison invented carbon fiber.

 

However, these efforts have failed to improve the performance of carbon fiber to a satisfactory level. During this period, carbon fiber research stagnated and was dormant.

 

 

Figure 1 The patent for the production technology of carbon fiber filament incandescent filament obtained by Edison in 1892

 

The emergence of artificial fiber chemical fiber provides the premise for the basic scientific research of high-performance carbon fiber technology in the United States

 

The emergence of artificial fiber chemical fiber has brought carbon fiber technology into the “reinvented” era. In the early 20th century, the emergence of artificial fibers such as viscose (1905) and acetate (1914), especially the commercialization of chemical fibers such as polyvinyl chloride (1931), polyamide (1936) and polyacrylonitrile (1950) in the mid-20th century, provided the premise for the United States to pioneer basic scientific research on high-performance carbon fiber technology.

 

In the mid-1950s, American William F. Abbott invented a method of carbonizing artificial fibers to improve the performance of carbon fibers. As a client of Carbon Wool Corporation, Abbott submitted a patent application for “Method for Carbonizing Fibers” to the U.S. Patent Office on March 5, 1956 (Serial No. 569,391), but it is unknown whether this application was patented.

 

On November 12, 1959, Abbott again filed the same patent application (Serial No. 852,530), and on September 11, 1962, the application was granted U.S. patent (Patent No. 3053775). (Figure 2)

 

The technical point of Abbott’s patent is: a processing technology for producing fiber-shaped carbon materials with high inherent density and good tensile strength. At that time, carbon fibers would break under very small mechanical forces. Abbott’s invention claims that it can make the carbon density and hardness of carbon fiber higher, and keep the fiber shape from being destroyed when mechanical force acts; the diameter is thinner, the surface is cleaner, and the flexibility and elasticity are better; the fiber diameter and performance can be designed and controlled; the raw materials must be regenerated cellulose fibers and synthetic fibers such as viscose, cuprammonia and saponified acetic acid, and natural fibers cannot be used.

 

Figure 2 US patents obtained by Abbott

 

Carbon Wool Corporation, which applied for the patent, was a company located in Ojai, California, USA. It was founded in 1955 and was later revoked by the tax department. Due to limited information, the details of the company and Abbott himself are still unknown.

 

Abbott’s patent was transferred to the Barnebey-Cheney Company of the United States. In 1957, Barnebey-Cheney Company began commercial production of cotton-based or rayon-based carbon fiber multifilaments, but it could only be used to produce products such as ropes, mats and wadding for high temperature resistance and corrosion resistance; it can be used independently as activated carbon fiber for adsorption.

 

Since then, basic scientific research and industrial technology research and development of high-performance carbon fibers have entered a peak period (Table 1).

 

Table 1 Overview of the early development of high-performance carbon fiber technology in the United States

 

Time	Company Name	Technology	Products or research results
1940- 1950	DuPont	In 1941, DuPont invented acrylonitrile fiber technology; in 1950, it began to produce and sell acrylonitrile fibers under the “Orlon” brand; in 1944-45, Winter, L. L. of Union Carbide Corp. discovered that it did not melt at ashing temperatures, which allowed it to be used as a carbon material to maintain fiber form.	In 1950, Houtz reported that the product obtained by heat-treating PAN fibers at 200°C in air had good fire resistance and was called “Black Orlon”.
1957	Barnebey -Cheney	Using W. F. Abbot’s patent; using rayon as a precursor to produce carbon fiber multifilaments.	Carbon fiber ropes, mats and flocculants.
1958年	Union Carbide	Heat-treating rayon at 1000°C and 2500°C to make rayon-based carbon fiber fabrics.	Composited with phenolic resin to manufacture rocket nozzle exit cones and reentry insulation layers, replacing glass fiber reinforced phenolic resin materials, passed the inspection of the US Air Force; used carbon fiber cloth strips as heating elements to heat walls; used to manufacture space shuttle noses and wings.
1959年		Discovered “graphite whiskers”.	Established a goal for carbon fiber technology.
1963年		Pre-impregnating rayon with an organic phosphoric acid derivative (cotton fabric flame retardant) to form the necessary “crystallization” during thermal cracking.	Commercial production of carbon fiber yarns began, and resins were reinforced by filament winding and fabric pre-impregnation, creating the “advanced composite materials” technology; continuous filaments were also used for filling and sealing materials.
1964年 8月		Stress-graphitizing or hot-stretching rayon at temperatures above 2800°C.	Developed true high modulus carbon fiber. *Earlier in April 1964, the Royal Aircraft Establishment of the United Kingdom developed PAN-based high modulus carbon fiber, which was the earliest truly high-modulus carbon fiber; at the same time, it also developed carbon fibers with high strength and high modulus (Type I) and high strength and medium modulus (Type II).
1965年 下半年		Launched a series of high-model carbon fiber products with the Thornel 25 brand.	Until 1978, the brand’s products were sold on the market; and HITCO was authorized to produce them; thereafter, they were discontinued due to high costs. From 1965 to 1970, the product was supported by the US Air Force.
1971- 1972年		Using the excellent acrylonitrile fiber precursor provided by Japan’s Toray Corporation, high-strength medium-model carbon fiber was produced.	This carbon fiber was the market-leading product for decades to come. Toray Corporation of Japan was the world’s main supplier of this product. No American company has made a big move in the market for this product, for unknown reasons.
1974- 1982年		In 1970, Leonard Singer discovered a method for preparing raw asphalt into intermediate or liquid crystal asphalt through flow and shear.	With the support of the US Air Force (AFML) and the US Navy (NSSC), in 1974, felt carbon fiber was produced; in 1975, continuous filaments of the Thornel P-SS brand were produced; from 1980 to 1982, high-modulus carbon fiber with a modulus of 830GPa was produced.

 

The Basic Scientific Research of High-Performance Carbon Fiber Technology has been Recognized as a “National Historic Chemical Landmark”

 

The National Historic Chemical Landmark is an activity carried out by the American Chemical Society (ACS) to discover and organize chemists and chemical events with historical influence in the United States. Each regional branch reports the people and events that have appeared in the region, and the American Chemical Society organizes experts to assess and identify them.

 

GrafTech International Ltd., located in Parma, Ohio, reported the “High Performance Carbon Fibers” project to the American Chemical Society. The company’s predecessor was Union Carbide Corp. ]]

 

On September 17, 2003, the American Chemical Society confirmed that the high-performance carbon fiber technology research conducted by the former US Union Carbide Corp.’s Parma Technical Center was a “chemical milestone in American history”; Roger Bacon discovered “graphite whiskers” and their ultra-high strength in 1958; Leonard S. Singer invented the preparation technology of mesophase pitch-based carbon fibers in 1970; they pioneered the scientific and technological foundation of carbon fiber reinforced composite materials and were pioneers in this field. (Figures 3 and 4)

 

Figure 3 At the 2003 “Chemical Milestones in American History” award ceremony, Nina McClelland, president of the American Chemical Society, awarded the medal for the discovery of high-performance carbon fiber to Lionel Batty, director of research and development at Gefurt International.

 

Figure 4 Cover of the commemorative album used in the ceremony of the American Chemical Society awarding the high-performance carbon fiber research “Chemical Milestone in American History”

 

Scientists at the Parma Technology Center pioneered the basic scientific research of high-performance carbon fiber technology

 

At the end of the 19th century, the lighting of American city streets relied on arc lamps. This lamp consists of two carbon electrodes connected to a power source. The charged particles flash between the two electrodes to release heat, forming an arc and releasing strong light. In 1886, the National Carbon Company was founded, marking the beginning of the synthetic carbon industry in the United States. Its earliest product was the carbon electrode for arc lamps.

 

In 1917, the National Carbon Company merged with Union Carbide Corp. to form Union Carbide & Carbon Corp. In 1957, Union Carbide & Carbon Corp. was renamed Union Carbide Corp. In the late 1970s, Union Carbide established an independent department to produce carbon fiber, which was later sold to Amoco Corporation and then to Cytec Industries Inc. In 1995, Union Carbide established UCAR Carbon Company; in 2002, it was renamed Gefut International.

 

In the late 1950s, Union Carbide established the Parma Technical Center in Cleveland to conduct basic scientific research. The center is a university-style corporate lab that was popular in the 1940s and 1950s. Its environment is simple and modern, and its management atmosphere is free and relaxed. It gathers many young scientists with different academic backgrounds and vigor to conduct their favorite research.

 

1. Roger Bacon discovered “Perfect Graphite”, laying the scientific foundation for high-performance carbon fiber technology

 

The basic scientific research on high-performance carbon fiber technology began in 1956.

 

Roger Bacon (1926–2007) (Figure 5) received his PhD in solid-state physics from Case Institute of Technology in 1955. In 1956, he joined the Parma Technical Center, where he worked until 1986.

 

Figure 5 Roger Bacon (1926–2007)

 

Initially, Bacon’s research goal was to measure the temperature and pressure at the triple point of carbon (the thermodynamic equilibrium point of solid, liquid and gas), which required measurements under conditions of nearly 100 atmospheres (atm) and 3900 degrees Kelvin (K, about 3626.85°C). The experimental device he used was based on the same principle as the early carbon arc lamp, except that the operating pressure was higher.

 

During his research, he found that when the pressure was low, the gaseous carbon on the negative electrode of the DC carbon arc furnace grew into stalagmites. These filaments are graphite whiskers embedded in the sediment in the shape of straw. The graphite whiskers are up to 1 inch (2.54 cm) long and only one-tenth the diameter of a human hair, but they can withstand bending and kinking without breaking, which is amazing.

 

In 1960, Bacon published a paper on this in the Journal of Applied Physics, which became a milestone in the history of basic research on high-performance carbon fiber technology. Bacon believes that graphite whiskers are graphite polymers, a pure form of carbon, with carbon atoms arranged in hexagonal sheets; they are rolled-up graphite sheets, in which the crystallographic c-axis is perpendicular to the rotation axis; the cross-section of its cylinder is circular or elliptical.

 

Graphite whiskers can be made in an argon environment at 92atm and 3900K (degrees Kelvin, about 3626.85°C). Its tensile strength, elastic modulus and room temperature conductivity are 20GPa, 700GPa and 65μΩ·cm, respectively, which are similar to single crystals. Therefore, although it is not a single crystal, it exhibits the properties of a single crystal along the axial direction of the filament.

 

In 1960, Bacon’s invention of graphite whiskers was awarded a US patent (patent number: 2957756) (Figure 6). Bacon believed at the time that the preparation of graphite whiskers was only a laboratory achievement, and there was still a long way to go to use its principles to manufacture carbon fibers with practical value.

 

The research over the next decade or so was aimed at obtaining low-cost, high-efficiency technology for producing high-performance carbon fibers with graphite whisker properties.

 

Figure 6 Patents obtained for Roger Bacon’s invention of graphite whiskers and the technology for preparing graphite whiskers

 

Sixty years after discovering graphite whiskers and their properties and inventing a method for preparing graphite whiskers in the laboratory, Roger Bacon was inducted into the National Inventors Hall of Fame on October 25, 2016. (Figure 7)

 

Figure 7 Roger Bacon was inducted into the National Inventors Hall of Fame

 

2. Advances in High-Strength and High-Modulus Carbon Fiber Technology and Early Commercial Applications

 

In 1959, scientists at the Parma Technology Center invented the preparation technology of high-performance rayon-based carbon fibers. Curry E. Ford and Charles V. Mitchell invented the process technology of heat-treating rayon at 3000°C to manufacture carbon fibers, producing the highest strength commercial carbon fibers at the time and obtaining a patent (patent number: 3107152) (Figure 8).

 

The U.S. Air Force Materials Laboratory soon adopted this rayon-based carbon fiber as a reinforcement for phenolic resin and developed a composite material for the thermal shielding layer of spacecraft. Its function is that when returning to the atmosphere, the missile or rocket shell rubs violently with the atmosphere, forming a high temperature on the surface, and the phenolic resin slowly decomposes after absorbing heat. The carbon fiber prevents the phenolic resin from being burned, ensuring that the missile completes its journey in the atmosphere.

 

In 1963, the research on carbon fiber reinforced resin composite material technology achieved a substantial breakthrough, and composite material technology entered the era of “advanced composite materials”. Before that, the reinforcement of resin-based composite materials had been dominated by glass fiber and boron fiber. Compared with glass fiber and boron fiber, carbon fiber as a reinforcement has a better cost-effectiveness.

 

Figure 8 Gary Ford’s invention patent for fibrous graphite

 

In 1964, Wesley A. Schalamon and Roger Bacon invented the technology for commercializing the manufacture of high modulus rayon-based carbon fibers; “hot-stretching” rayon at a high temperature of more than 2800° C makes the graphite layer orientation almost parallel to the fiber axis; the key to the technology is to stretch the fiber during the heating process, rather than stretching it after reaching a high temperature.

 

This process increases the fiber modulus by 10 times and is a key step in preparing carbon fibers with the same properties as graphite whiskers. At the end of 1965, Thornel 25 carbon fibers manufactured using this technology were put on the market.

 

In the following 10 years, Union Carbide Corporation of the United States developed a series of high modulus carbon fibers using a high-temperature hot stretching process, and the modulus of the Thornel series products reached 830GPa. Schalamon and Bacon’s invention was patented in 1973 (patent number: 3716331) (Figure 9).

 

Figure 9 Wesley Salamon’s invention patent for the preparation process of high modulus carbon fiber

 

3. Leonard Singer Invented the Manufacturing Technology of Mesophase Pitch-Based Graphite Fiber

 

During the high-temperature heat treatment process, the internal structure of the material will change from disorder to order. Carbon-containing substances can be carbonized into carbon materials with a carbon content of about 99% at 1000°C; at 2500°C, they can be carbonized into carbon materials with a carbon content of 100%. However, not all carbon-containing substances can obtain true graphite after high-temperature heat treatment.

 

Only those carbon-containing substances with sufficiently orderly structures that can form graphite whiskers can be made into pure graphite with high thermal conductivity, high electrical conductivity and high hardness through high-temperature heat treatment. Polyacrylonitrile and rayon do not belong to this type of carbon-containing substances, so it is impossible to make graphite fibers through high-temperature heat treatment. To manufacture higher-performance carbon fibers, a new material must be used as a precursor.

 

Leonard S. Singer (1923-2015, Figure 10) paved the way for this. In the mid-1950s, after receiving his Ph.D. from the University of Chicago, Singer joined the Parma Technical Center to conduct research on electron spin resonance.

 

Figure 10 Leonard Singer (1923–2015)

 

Although he had no experience in carbon or graphite research, he tried to study the mechanism of carbonization. Heating raw materials such as petroleum and coal produces asphalt-like substances. Petroleum-based and coal-based asphalt are the basic raw materials for making carbon and graphite products. Asphalt contains more than 90% carbon, which is much higher than rayon and acrylonitrile. They are complex mixtures composed of hundreds of aromatic substances with a wide molecular weight distribution and are important high-carbon precursor organic substances. At the same time, studies have shown that most substances in such mixtures are isotropic, and through further polymerization, their molecules can be oriented in a layered form.

 

In 1970, Singer solved the key technology for preparing high-modulus asphalt-based carbon fibers; the core of the technology is that liquid crystal or mesophase is the key to achieving high modulus properties. 80-90% of the weight of mesophase asphalt can be converted into carbon, and it has excellent thermal conductivity, electrical conductivity, oxidation resistance, low thermal expansion rate and other properties. He successfully processed the raw pitch into a mesophase or liquid crystal pitch, and then oriented it through flow and shear.

 

Singer and his assistant Allen Cherry designed a “taffy-pulling” machine and used it to apply tension to the viscous mesophase pitch to rearrange its molecules, and then heat treat it.

 

This technology was successful and they produced highly oriented graphite fibers.

 

In 1975, Union Carbide began commercial production of Thornel P-SS brand continuous filaments; in 1980-82, its modulus reached 690-830GPa.

 

In 1977, Singer obtained a patent for graphite fibers and their manufacturing process (patent number: 3919387) (Figure 11). The U.S. Air Force Materials Laboratory (AFML) and the U.S. Navy (NSSC) funded Singer’s research.

 

Figure 11 Leonard Singer’s patent for preparing high mesophase content asphalt fiber

 

Although asphalt is a relatively cheap raw material, the cost difference of carbon fiber made from it is very large. Mesophase asphalt-based carbon fibers with low modulus, non-graphitization, and relatively cheap are used to manufacture aircraft brake pads and reinforced cement. Mesophase asphalt-based graphite fibers with high-end performance such as ultra-high modulus and ultra-high thermal conductivity and high cost are used to manufacture key components such as rocket nozzle throat linings, missile nose cones, and satellite structures. They are irreplaceable key aerospace materials.

 

Miss and return of polyacrylonitrile-based carbon fiber technology in the United States

 

Rayon, polyacrylonitrile or asphalt are the three major precursors of carbon fiber. Among them, the comprehensive performance of acrylonitrile-based carbon fibers (Polyacrylonitrile ‹PAN›-based Carbon Fibers) is particularly outstanding, and has replaced rayon-based carbon fibers in many fields. The reason why the performance of carbon fiber has been leapfrogged is the invention of better acrylonitrile fibers. Scientists in the United Kingdom and Japan first developed pure acrylonitrile polymers. During processing, the continuous carbon and nitrogen atom chains in their molecular chains can form highly oriented graphite-like layers, thereby reducing the need for hot stretching.

 

In 1941, DuPont invented acrylonitrile fiber technology in the United States. In 1950, DuPont began commercial production of acrylonitrile fibers under the “Orlon” brand. In 1944-45, L. L. Winter of Union Carbide discovered that acrylonitrile does not melt at ashing temperatures and believed that it could be made into carbon materials in fiber form.

In 1950, Houtz discovered that heat-treated acrylonitrile fibers in air at 200°C produced products with good fire resistance. Later, similar products were called “Black Orlon”. Originally, these discoveries should have been the starting point for the development of high-performance PAN-based carbon fiber technology, but due to excessive focus on rayon-based carbon fiber technology research, American scientists missed the development opportunity of PAN-based carbon fiber technology.

 

Japanese scientists have been quietly conducting research on PAN-based carbon fiber technology with little knowledge from Western scientists.

 

In 1961, Akio Shindo of the Government Industrial Research Institute of Japan produced PAN-based carbon fiber with a modulus of 140GPa in the laboratory, which is three times higher than the modulus of rayon-based carbon fiber.

 

Akio Shindo’s invention was rapidly promoted by the Japanese scientific and industrial circles. Toray Industries of Japan developed acrylonitrile precursor with excellent performance and established a carbon fiber pilot plant, thus occupying the leading position in PAN-based carbon fiber technology.

 

In 1970, Toray Corporation of Japan signed a technical cooperation agreement with Union Carbide Corporation of the United States. The latter exchanged carbonization technology for the former’s acrylonitrile precursor technology and soon produced high-performance PAN-based carbon fiber, thus bringing the United States back to the forefront of carbon fiber technology.

 

Conclusion

 

Looking at the early development of carbon fiber technology in the United States, the following laws and facts are worth noting:

 

(I) Carbon Fiber was Born from the Invention of the Product of Electro-Optical Conversion Device.

 

The mid-to-late 19th century was a period of explosive growth of the scientific revolution and the industrial revolution. A large number of scientific discoveries and technological inventions emerged, contributing to the civilization of human society entering the modern era. Carbon fiber technology was born in such an era. In order to light up the dark night, Swan and Edison invented the electric light that converts electricity into light. As the light source of the electric light, carbon fiber was quietly born.

 

The newly born carbon fiber did not attract much attention. Because the electric light was the focus of people’s attention at that time. Although the importance of carbon fiber has been temporarily ignored, as long as there is vitality, it will definitely go through the regular process of birth, growth, maturity, decline and rebirth. Technology and products are the same as organisms.

 

(II) High-Performance Carbon Fiber Technology was Born from Scientific Discoveries in Basic Research.

 

Graphite whiskers, their characteristics and microstructures, were discovered in basic scientific research. This discovery provides direction and goals for the research of high-performance carbon fiber manufacturing technology. In the 1950s-1970s, the discovery of basic scientific research and the invention of a large number of engineering technologies contributed greatly to the maturity and perfection of high-performance carbon fiber technology.

 

(III) There is a “US-Japan Alliance” in the Field of High-Performance Carbon Fiber Technology.

 

The reason why Japanese scientist Akio Shindo came up with the idea of ​​conducting carbon fiber research was because he was inspired by the reports of technological progress in this field in the United States. After successfully commercializing PAN-based carbon fiber, Japan’s Toray Industries signed a precursor and carbonization technology exchange agreement with Union Carbide Corporation of the United States, allowing the two companies to simultaneously possess the full process technology for high-performance carbon fiber production.

 

Since then, other Japanese companies have also produced acrylonitrile fiber precursors with excellent performance. Sumitomo Corporation of Japan provides acrylonitrile fiber precursors to Hercules Incorporated of the United States, and is authorized by Courtaulds PLC of the United Kingdom to produce carbon fibers. 1 US-Japan technical cooperation has enabled high-performance carbon fiber technology to be rapidly developed and widely used. Today, all Boeing aircraft in the United States use carbon fibers produced by Japan’s Toray Industries.

 

In 2015, Japan’s Toray Industries built a full-process carbon fiber production plant from acrylonitrile precursor to carbonization in the United States to meet Boeing’s rapidly growing demand for carbon fibers in the production of advanced aircraft. The technological interaction between the United States and Japan is one of the important factors in promoting the continuous development of high-performance carbon fiber technology to the forefront.