ARAMIDS
Kevlar®
An aramid fiber introduced by DuPont in 1971, Kevlar has become the predominant fiber in the racing sector of the sailcloth industry. It is stronger than steel for its weight and has a modulus that is five times greater than polyester. When Kevlar was first introduced there were two types: Type 29 and Type 49 (High Modulus). Type 49 has a 50% higher initial modulus than Type 29 and lower flex strength. Other Kevlar styles (Types 129, 149 and 159) have also been developed, but have seen limited use in sails, since the higher strength goes hand in hand with lower flex strength. Most recently, DuPont has introduced Kevlar Edge, a fiber developed specifically for the sailcloth industry that has a 25% higher tenacity and better modulus than Kevlar 49. However, the benefits of Kevlar 49 vs. Kevlar Edge are still being debated. Additional drawbacks of Kevlar include poor UV resistance (Kevlar loses strength roughly twice as quickly in sunlight as polyester and, when affected, the gold Kevlar fibers turn brown) and rapid loss of strength with flexing, folding and flogging. Minimal flogging and careful handling can greatly extend the life of a Kevlar sail.
Technora®
Produced in Japan by Teijin, Technora exhibits a similar or somewhat lower initial modulus than Kevlar 29 and slightly higher resistance to flex fatigue. The fiber’s lower UV resistance is enhanced by dying the naturally gold fiber black. Technora is most often used as bias support (X-ply) in laminate sailcloth.
Twaron®
Produced by Teijin, Twaron is chemically and physically similar to DuPont’s Kevlar®. High modulus Twaron (HMT) has similar stretch properties to Kevlar 49, greater tensile strength and better UV resistance. Like Kevlar, the fiber is a bright gold color. As the demand for Kevlar increases beyond supply capabilities, more and more sailcloth manufacturers are switching to Twaron.
