In the spring of 1965, a group of DuPont researchers developed a polymer material with completely new physical properties in their laboratory, which was then called FIBER B. Researchers have learned that if a high-molecular substance’s molecules can be polymerized from symmetric molecules with para-direction rather than meta-position oriented molecules , then a super molecular bond can be produced.
Img Source: Kevlar Felt Belt
Kevlar was invented by Stephanie Kwollek - a Polish-American chemist. Kevlar is one of the aromatic fibers of DuPont. It has three different varieties.
Kevlar49 is mainly used to reinforce plastics, it is a new level of composite material. Kevlar49 can also be used to coat fabrics, ropes and cables, etc. Kevlar49 also has a strong tensile strength.
Kevlar29 is a widely used material in industry, it is suitable for manufacturing ropes, cables and coated fabrics and protective clothing. Kevlar's tensile strength is similar to kevlar49.
Kevlar material has the same performance as kevlar29, which is mainly used to reinforce rubber products, especially tires, tapes and fire hoses.
Kevlar has very good tensile properties. Kevlar has high strength which is five times that of steel of the same quality. Its density is only about one-fifth of steel (Kevlar density is 1.44 grams per cubic centimeter; steel density is 7.859 grams per cubic centimeter).
In terms of physical properties, kevlar49's tensile strength is more than 2 times higher than that of polyamide and polyester fibers, and 15% higher than that of glass fibers. The modulus or rigidity of kevlar49 is more than 20 times higher than that of polyamide fibers. The breaking elongation of kevlar49 is relatively low. The density of kevlar49 is higher than that of polyamide and polyester fibers, but lower than that of glass fibers. Kevlar49 weighs only one-fifth that of stainless steel, but kevlar49 is stronger than stainless steel.
The linear stress-strain fracture curve of kevlar49 filament is similar to glass fiber and other inorganic reinforcing fibers. Kevlar49 has superior toughness, so kevlar49 has good textile processing performance and high impact strength. Kevlar49 has good thermal stability. When the test temperature reaches 180 degrees Celsius, kevlar49 can still maintain a relatively high percentage of room temperature performance.