Kevlar is a material developed by DuPont in 1965 but it was only used in 1970 for commercial use. Kevlar is used in body armor and armored vehicles, it is also applied in clothing to protect the user from cuts. Sports equipment such as bicycle tires to stop punctures, it is applied to table tennis paddles, motor cycle clothing, and racing sails. Kevlar has even been used in audio equipment since it has acoustic properties, drumheads, woodwind reeds, rope, cable, brakes, electricity generation, construction of buildings, and expansion hoses and joints.
Kevlar is strong because of the weave which is very similar to small spider webs. It was invented by Stephanie Kwolek and Herbert Blades. The weave consists of a liquid and a solid also known as an aramid weave. These weaves corrode in exposed to chlorine but is resistant to heat.
There are different types of Kevlar, they are all numbered and have their own use. Kevlar K-29 for example is used industrially for cables and brakes and armor while Kevlar K-49 is used in tires to replace rubber and bicycle frames but also in the hull of a boat because it is incredibly strong.
The chemical composition of Kevlar is poly para-phenyleneterephthalamide (composite.about.com). Aramids belong in the nylon family.
Kevlar is also very light and extremely strong of course and the tensile strength is high. However it does absorb moisture which makes it more sensitive to environments it is also harder to cut because you will need special scissors.
The material is rather expensive to get and can get to about 33 dollars per yard but you have to buy in great amounts.
This is a table of the three main Kevlar types 29, 49, and 149. (composite.about.com)
| Grade | Density g/cm^3 |
Tensile Modulus GPa |
Tensile Strength GPa |
Tensile Elongation % |
| 29 | 1.44 | 83 | 3.6 | 4.0 |
| 49 | 1.44 | 131 | 3.6–4.1 | 2.8 |
| 149 | 1.47 | 186 | 3.4 | 2.0 |
Sources:
http://composite.about.com/od/aboutcompositesplastics/l/aa050597.htm
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