Teflon-coated fibreglass was ideal for the outer layer of the Apollo space suits, but has been less successful against Montreal’s snowfall.
More than 27 million people flocked to Chicago’s Columbian Exposition in 1893, a six-month celebration that honoured the arrival of Christopher Columbus to the New World. They came to see replicas of Columbus’s ships, to ride the original Ferris wheel and to watch Harry Houdini and his brother Theo perform at the fair’s midway. They also came to ogle at the Libbey Glass Company’s famous glass dress! If they thought the dress would be transparent, they were disappointed. It wasn’t. The dress was opaque, actually woven of silk and thin fibres of glass. It was destined to be no more than a curiosity, given that it was heavy and, due to the easy breaking of the glass fibres, rather prickly. But just 76 years later, fabric made of glass fibres would hit the news again as astronauts walked on the moon protected by space suits with an outer layer of glass fibres.
Glass fibre, as the term implies, refers to a thin thread made of glass. I was familiarized with such fibres back in my graduate school days when sometimes there was a need to bend glass tubing into a desired shape. This can be done by softening the glass in the flame of a Bunsen burner, but if instead of bending, the heated glass is quickly pulled, it forms a thread. We used to play around to see who could produce the longest and thinnest thread. With a little practice, you can produce a fibre that is thin enough to be woven into fabric. That fabric would be referred to as “fibreglass.”
Today of course this is all done by machines, and threads can be produced that are thinner than a human hair. When matted together these fibres can trap air, making for an excellent insulating material that is commonly used in walls and attics. In this case, description of the material as “fibreglass” is accurate because it is made of nothing but glass. However, confusion can arise since “fibreglass” is also commonly used to describe a composite material made by impregnating a network of glass fibres with a fluid resin that then “cures” to form a hard substance.
This technology was first worked out by German chemists in the late 1930s. They discovered that polyester resin can be cured by combining it with styrene and a hydrogen peroxide “initiator.” The peroxide triggers a reaction that allows the styrene to crosslink the long polyester molecules to form a rigid network. While the mixture is still fluid, it can be poured into moulds where it will then harden as the cross-linking reaction proceeds.
During the Second World War, British intelligence agents were successful in stealing the secret for this reaction from the Germans and turned it over to Cyanamid, an American company. It wasn’t long before airplane parts, panels for ships, and domes to protect radar equipment were being manufactured. After the war, “glass reinforced plastic” found its way into fishing poles, pleasure boats, and in 1953, into the body of Chevrolet’s Corvette.
When Alan Shepard, America’s first astronaut, was launched into space in 1961, he was sitting in a fibreglass seat custom-molded to his body. In his Mercury capsule he was protected from the heat of re-entry by a heat shield consisting of an aluminum honeycomb covered with multiple layers of fibreglass. The Apollo capsule that would take astronauts to the moon, as well as the lunar lander, were insulated with fibreglass.
The journey to the moon required extensive testing of the Apollo capsule on the ground before the first low Earth orbital test, planned for 1967. Tragically, that launch never took place because astronauts Gus Grissom, Ed White and Roger Chaffee were killed in a fire that engulfed the capsule during a ground test. The atmosphere in the capsule had been designed to be 100-per-cent oxygen in order to save weight, and while oxygen does not burn, it supports combustion. An electrical spark triggered the flash fire that was fed by combustible materials such as Velcro, extensively used in the capsule.
The astronauts had been wearing fireproof suits made of DuPont’s Nomex, but it could not stand up to the intensity of the flames. NASA launched a full scale investigation and tasked companies to come up with a superior material. That challenge was met by the Owens-Corning Company with “Beta Cloth,” made of tightly woven, extremely thin glass fibres coated with Teflon. This was totally non-flammable, had a higher melting point than Nomex, and the tight weave prevented penetration by gases or microscopic particles. It was ideal for the outer layer of the Apollo space suits.
Walter Bird, an engineer who in the 1940s had worked on designing coverings for radar installations, saw the potential of “Beta cloth” in earthly applications. In 1975, his company Birdair installed a roof made of panels of Teflon-coated fibreglass on Detroit’s Pontiac Silverdome. This then forayed into similar installations around the world, including the sail-like structures that top Vancouver’s Canada Place, the covering of the Dallas Cowboys Stadium, and the roof of Montreal’s Olympic Stadium.
Montreal’s stadium was build for the 1976 Games, but its original roof, which was designed to be retractable and was made of Kevlar, DuPont’s famous bulletproof material, was not put into place until 1987. Unfortunately, it did not stand up well to the rigours of opening and closing. It was replaced in 1998 by a non-retractable roof constructed of panels of Birdair’s fibreglass. Although the fabric stood up to the demands of outer space, it could not deal with Montreal’s snowfall. The weight of snow that piled up on the roof caused numerous rips, and the city is once again looking for a new roof. Given that chemists and engineers were able to solve the monumental problems involved in putting men on the moon, one would think they should be able to put a roof on our Olympic Stadium. Then we just have to find a team to play under it.
Joe Schwarcz is director of McGill University’s Office for Science & Society (mcgill.ca/oss). He hosts The Dr. Joe Show on CJAD Radio 800 AM every Sunday from 3 to 4 p.m.
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