During this uniform series, we've focused on firefighter and police uniforms. This final post of the series focuses on an amazingly strong and lightweight textile used in both uniforms, Kevlar.
In the mid-60s, Stephanie Kwolek, a chemist working for DuPont, invented Kevlar, opening the doors for polymer chemistry. Kevlar is an extremely strong, flexible, and tremendously flame, heat, and cut-resistant textile with a high tensile strength - five times stronger than steel, and 20 times stronger than steel when underwater. Kevlar's superior strength lies in its hydrogen bonds that strengthen the monomer (a molecule that chemically binds to other molecules), making it into a strong polymer chain.
Kevlar is used not only in emergency services clothing and equipment, but has uses in industrial, workplace, and military safety, and is present in automotive and sports equipment, rope, and fiber optics. Many people rely on the strength of Kevlar to confidently and effectively do their jobs.
Firefighting and Kevlar
In high temperature situations, Kevlar can withstand temperatures up to 300°C and still retain its strength properties, so it is an ideal material for firefighting uniforms and equipment. Kevlar is virtually indestructible and with the exception of a few powerful acids, solvents are ineffective at damaging Kevlar. Kevlar is slightly susceptible to ultraviolet light.
Toronto firefighter boots are made of heavy, thick, and waterproof rubber, insulated with felt and heat-resistant Kevlar. Bunker coats and pants of the firefighting uniform are made of Kevlar and Nomex (another DuPont flame-resistant textile) with a water barrier to keep out water and chemicals. The fabric of the outer uniforms are breathable, allowing metabolic heat to escape and reducing heat stress in the body.
"DuPont™ NOMEX® and DuPont™ KEVLAR® brand fibers will not melt, drip, or support combustion, providing a stable barrier that helps minimize burn injuries. The flame resistant properties of NOMEX® and KEVLAR® are permanent; they cannot be washed out or removed in any way. Durable DuPont™ Teflon® HT water-repellent treatments prevent water from compromising valuable air layers that provide the bulk of the garments' thermal insulation." (Source.)
Kevlar also in a firefighter's SCBA, self-contained breathing apparatus. The aluminum oxygen tank is wrapped in Kevlar and strapped to the back, protecting the firefighter from the combustible gas from exploding during fire calls.
For more information about DuPont's firefighting protective gear, please see this page of their site.
Kevlar's lightweight ballistic and stab-resistant textile technology is used in police gear and military body armor; it is the bullet-stopping material that makes up bullet-proof vests. When I toured 51 Division in Toronto, I had a look inside of the vest to inspect the Kevlar plate within the vest. It was spongy and firm, and felt like dense foam.
The DuPont site explains Kevlar as "bullet-resistant tactical vests work by “catching” a bullet in a multilayer web of woven fabrics... Whether it’s engaging a fast-moving projectile or helping to stop the blunted bullet, body armor made with Kevlar® fiber helps offer law enforcement officers superior protection in multiple situations."
Kevlar is such an amazing produce that many police officers owe their lives to this DuPont textile. Their website features videos of survivor stories from police officers who owe their lives to their bullet-proof Kevlar vests.
Kevlar is a major component of emergency services uniforms in Toronto and throughout the world. Kevlar marries science and clothing to form the world's most cutting-edge protective textile, so people in dangerous jobs can feel safe and confident in their work.