Polymer Fabric Protects Firefighters, Military, and Civilians

Originating Technology/NASA Contribution

PBI fiber
The PBI plant, located in Rock Hill, South Carolina, produced its first commercial bale of PBI fiber on March 18, 1983.

Insulating and protecting astronauts from temperature extremes, from the 3 K (-455 °F) of deep space to the 1,533 K (2,300 °F) of atmospheric reentry, is central to NASA’s human space flight program. While the space shuttle and capsule vehicles necessarily receive a great deal of thermal barrier and insulation protection, at least as much attention is also paid to astronaut clothing and personal gear. NASA has spent a great deal of effort developing and refining fire-resistant materials for use in vehicles, flight suits, and other applications demanding extreme thermal tolerances, and kept a close eye on the cutting edge of high-temperature stable polymers for its entire 50-year history.

In the late 1950s, Dr. Carl Marvel first synthesized Polybenzimidazole (PBI) while studying the creation of high-temperature stable polymers for the U.S. Air Force. In 1961, PBI was further developed by Marvel and Dr. Herward Vogel, correctly anticipating that the polymers would have exceptional thermal and oxidative stability. In 1963, NASA and the Air Force Materials Laboratory sponsored considerable work with PBI for aerospace and defense applications as a non-flammable and thermally stable textile fiber.

On January 27, 1967, the severity and immediacy of the danger of fire faced by astronauts was made terribly clear when a flash fire occurred in command module 012 during a launch pad test of the Apollo/Saturn space vehicle being prepared for the first piloted flight, the AS-204 mission (also known as Apollo 1). Three astronauts, Lieutenant Colonel Virgil I. Grissom, a veteran of Mercury and Gemini missions; Lieutenant Colonel Edward H. White II, the astronaut who had performed the first U.S. extravehicular activity during the Gemini program; and Lieutenant Commander Roger B. Chaffee, an astronaut preparing for his first space flight, died in this tragic accident.

A final report on the tragedy, completed in April 1967, made specific recommendations for major design and engineering modifications, including severely restricting and controlling the amount and location of combustible materials in the command module and the astronaut flight suits. NASA intensified its focus on advanced fire-resistant materials, and given the Agency’s existing familiarity with the fabric and its inventor, one of the first alternatives considered was PBI.

Partnership

NASA contracted with Celanese Corporation, of New York, to develop a line of PBI textiles for use in space suits and vehicles. Celanese engineers developed heat- and flame-resistant PBI fabric based on the fiber for high-temperature applications. The fibers formed from the PBI polymer exhibited a number of highly desirable characteristics, such as inflammability, no melting point, and retention of both strength and flexibility after exposure to flame. The stiff fibers also maintained their integrity when exposed to high heat and were mildew, abrasion, and chemical resistant.

Throughout the 1970s and into the 1980s, PBI was instrumental to space flight, seeing application on Apollo, Skylab, and numerous space shuttle missions. Applications ran the gamut from the intended applications in astronaut flight suits and clothing, to webbing, tethers, and other gear that demanded durability and extreme thermal tolerance.

Product Outcome

Firefighters wearing protective PBI suits during a training fire
Andre Baur, a firefighter instructor in Switzerland, runs out of a training fire that has gotten out of hand. Like many other “Golden Knights” around the world, Andre escaped with only minor injuries.

In 1978, PBI was introduced to fire service in the United States, and Project FIRES (Firefighters Integrated Response Equipment System) lauded a recently developed outer shell material for turnout gear, PBI Gold. In 1983, PBI fibers were made commercially available and a dedicated production plant opened in Rock Hill, South Carolina, to meet demand. In 1986, NASA Spinoff chronicled this first phase of PBI’s history, and Marvel was awarded the “National Medal of Science” by President Ronald Reagan.

Since 1986, PBI has undergone a steady evolution into countless military and civilian applications and established a distinct profile and reputation in the fire retardant materials industry. In 2005, Celanese Corporation sold the PBI fiber and polymer business to PBI Performance Products Inc., of Charlotte, North Carolina, which is under the ownership of the InterTech Group, of North Charleston, South Carolina.

Produced by a dedicated manufacturer that takes great pride in the history and future of the product, the fabrics incorporating PBI have become prominent players in such diverse applications as firefighting and emergency response, motor sports, military, industry, and (still) aerospace. PBI Performance Products now offers two distinct lines: PBI, the original heat and flame resistant fiber; and Celazole, a family of high-temperature PBI polymers available in true polymer form.

  • PBI fabric withstands the dangers associated with firefighting, arc flash, and flash fire. In 1992, lightweight PBI fabrics were adapted for flame-resistant work wear for electric utility and petrochemical applications, and are now providing flame protection for U.S. Army troops in Afghanistan and Iraq. Short-cut PBI fibers were introduced for use in automotive braking systems and PBI staple fibers are employed as fire blocking layers in aircraft seats.
  • PBI Gold blends 40 percent thermal-resistant PBI fibers with 60 percent high-strength aramid, resulting in a fabric which does not shrink, become brittle, or break open under extreme heat and flame exposure. PBI Gold provides firefighters and industrial workers with superior protection and meets or exceeds every National Fire Protection Association (NFPA) and EN 469 (rating standard for protective clothing for firefighters) requirement. In 1994, the New York City Fire Department specified the use of PBI Gold fabric engineered in black for their turnout gear. Over the last 10 years, PBI Gold has grown internationally, with major industrial, military, and municipal fire brigades specifying the product across Europe, the Middle East, Asia, Australia, and the South Pacific.
  • PBI Matrix employs a “power grid,” a durable matrix of high-strength aramid filaments woven into the PBI Gold fabric to enhance and reinforce its resistance to wear and tear while retaining its superior flame and heat protection. In 2003, PBI Matrix was commercialized and introduced in the United States as the next-generation PBI for firefighter turnout gear. In 2008, Matrix will be introduced in Europe.
  • PBI TriGuard fabric is a three-fiber blend of PBI, Lenzing FR, and MicroTwaron designed for flame protection, comfort, and durability. This advanced fabric meets or exceeds all U.S. Department of Labor Occupational Safety and Health Administration (OSHA) and NFPA standards and is certified for wildlands, special operations, and motorsports applications, as well as the petrochemical, gas utility, and electric utility industries. PBI TriGuard and PBI Gold knits are now in use at several major motorsport racetracks around the country.
  • Celazole T-Series is a form-, shape-, and an injection-moldable blend of PBI and PEEK (polyetheretherketone) polymers.
  • Celazole U-Series utilizes PBI’s high-heat dimensional stability, strength, and chemical resistance to allow it to be formed into parts and used in the tools that produce flat panel displays and in the plasma etch chambers used to make semiconductor wafers.

New applications for PBI are continuing to come to light in new fields that demand material stability at high temperatures. PBI is now being developed into high-temperature separation membranes that increase efficiency in ethanol production and separate carbon dioxide from natural gas for carbon dioxide sequestration, and will see application in hydrogen fuel cells. PBI in short-cut form has also been used as a safe and effective replacement for asbestos. Fittingly, PBI may also return to space as part of NASA’s Constellation Program, as the polymer once applied for space suits in the Apollo and Skylab missions is under consideration for use as insulation material in the rocket motors for NASA’s next generation of spacecraft, the Ares I and Ares V rockets.

PBI TriGuard™ is a trademark, and PBI Gold®, PBI Matrix®, and Celazole® are registered trademarks of PBI Performance Products Inc.

Lenzing FR® is a registered trademark of Lenzing Fibers GmbH.

MicroTwaron™ is a trademark of Akzo N.V.

Sensors Provide Early Warning of Biological Threats

Originating Technology/NASA Contribution 

A postage stamp-size biosensor holding millions of carbon nanotubes
Containing millions of carbon nanotubes, the NASA biosensor can alert inspectors to minute amounts of potentially dangerous organic contaminants.

The Centers for Disease Control and Prevention (CDC) estimates there are between 4 and 11 million cases of acute gastrointestinal illnesses in the United States each year—caused by pathogens in public drinking water. The bacteria Escherichia coli (E. coli) and Salmonella have within the past few years contaminated spinach and tomato supplies, leading to nationwide health scares. Elsewhere, waterborne diseases are devastating populations in developing countries like Zimbabwe, where a cholera epidemic erupted in 2008 and claimed over 4,000 lives.

Scientists have found an unexpected source of inspiration in the effort to prevent similar disasters: the search for life on Mars. The possibility of life on the Red Planet has been a subject of popular and scientific fascination since the 19th century. While Martian meteorites have turned up controversial hints of organic activity, and NASA’s exploratory efforts have delivered important discoveries related to potential life—the presence of water ice, and plumes of methane in Mars’s atmosphere—direct evidence of organisms on our closest planetary relative has yet to be found.

In order to help detect biological traces on Mars, scientists at Ames Research Center began work on an ultrasensitive biosensor in 2002. The chief components of the sensor are carbon nanotubes, which are the major focus of research at the Center for Nanotechnology at Ames—the U.S. Government’s largest nanotechnology research group and one of the largest in the world. Tubes of graphite about 1/50,000th the diameter of a human hair, carbon nanotubes can be grown up to several millimeters in length and display remarkable properties. They possess extreme tensile strength (the equivalent of a cable 1 millimeter in diameter supporting nearly 14,000 pounds) and are excellent conductors of heat and electricity.

It is the nanotubes’ electrical properties that Ames researchers employed in creating the biosensor. The sensor contains a bioreceptor made of nanotubes tipped with single strands of nucleic acid of waterborne pathogens, such as E. coli and Cryptosporidium. When the probe strand contacts a matching strand from the environment, it binds into a double helix, releasing a faint electrical charge that the nanotube conducts to the sensor’s transducer, signaling the presence of the specific pathogens found in the water. Because the sensor contains millions of nanotubes, it is highly sensitive to even minute amounts of its target substance. Tiny, requiring little energy and no laboratory expertise, the sensor is ideal for use in space and, as it turns out, on Earth as well.

Partnership

“Carbon nanotubes are the wonder material of nanotechnology,” says Neil Gordon, president of Early Warning Inc., based in Troy, New York. “The opportunity was ripe to put that technology into a product.” Gordon encountered the director of the Center for Nanotechnology, Meyya Meyyappan, at a number of industry conferences, and the two discussed the possible terrestrial applications of NASA’s biosensor. In 2007, Early Warning exclusively licensed the biosensor from Ames and entered into a Space Act Agreement to support further, joint development of the sensor through 2012.

Product Outcome

Early Warning initially developed a working version of the NASA biosensor calibrated to detect the bacteria strain E. coliO157:H7, known to cause acute gastrointestinal illness. It also detects indicator E. coli, commonly used in water testing. In the process, the company worked out a method for placing multiple sensors on a single wafer, allowing for mass production and cost-effective testing. In April, at the 2009 American Water Works Association “Water Security Congress,” Early Warning launched its commercial Biohazard Water Analyzer, which builds upon the licensed NASA biosensor and can be configured to test for a suite of waterborne pathogens including E. coliCryptosporidiumGiardia, and other bacteria, viruses, and parasitic protozoa. The analyzer uses a biomolecule concentrator—an Early Warning invention—to reduce a 10-liter water sample to 1 milliliter in about 45 minutes. The concentrated sample is then processed and fed to the biosensor. The entire process takes about 2 hours, a drastic improvement over typical laboratory-based water sampling, which can take several days to a week. The sensor operates in the field via a wired or wireless network and without the need for a laboratory or technicians, allowing for rapid, on-the-fly detection and treatment of potentially dangerous organic contaminants.

The Early Warning water analyzer
Early Warning’s analyzer feeds a concentrated water sample to its biosensor, providing rapid pathogen detection.

“The sensor is incredibly sensitive and specific to the type of pathogen it is calibrated to detect in the water,” says Gordon. “Instead of just detecting coliforms in the water that may or may not indicate the presence of pathogens, we will know if there are infectious strains of SalmonellaE. coli, or Giardia that could sicken or even kill vulnerable people if consumed.” (Coliform bacteria levels typically indicate water and food sanitation quality.)

The water analyzer has multiple applications, notes Gordon. Early Warning’s system can monitor recreational water quality at beaches and lakes, which can be contaminated by animal feces, farming activities, and infectious pathogens in human waste. Agricultural companies may use the analyzer to test feed water for cattle, and food and beverage companies may employ the sensor to ensure the purity of water used in their products. Health care organizations have expressed interest in using the analyzer to test water from showers and other potential sources of pathogens like Legionella, which causes the flu-like Legionnaires’ disease.

Early Warning and Kansas State University, in Manhattan, Kansas, are collaborating on sensor enhancements such as improving the safety of imported produce. Since the skins of fruits and vegetables are potential sites of dangerous pathogens, inspectors could collect water sprayed on the produce and, using the analyzer, know within a few hours whether a particular shipment is contaminated. Last year, Kansas State was selected as the home for the U.S. Department of Homeland Security’s new National Bio and Agro-Defense Facility, which could also benefit Early Warning.

“We’re eager to show how the private sector, government agencies, and academia can work together to evolve this platform into products that benefit our citizens,” says Gordon. With an aging U.S. water and wastewater infrastructure, increasingly severe weather systems, global travel and food imports affecting the proliferation of disease-causing organisms, and more than 1 billion people worldwide without access to safe water (according to the World Health Organization), the fruits of this partnership may be more necessary than ever.