Presentation on theme: "Kevlar is a synthetic material being utilized in numerous applications. Of particular importance is the use of Kevlar in body armor. In 1965 Stephanie."— Presentation transcript:
Kevlar is a synthetic material being utilized in numerous applications. Of particular importance is the use of Kevlar in body armor. In 1965 Stephanie Kwolek, a chemist at the DuPont Company, developed a synthetic material which was patented as Kevlar in 1966. This development was of significant importance as, in the years to follow, it allowed for great advances in numerous fields, such as the aerospace industry, building materials, aviation, and the automobile industry. Hexamethylphosphoramide(HMP A) was first polymerization solvent used. However, HMPA caused tumors in rats, so it was deemed unsafe. HMPA
IUPAC name: poly(p-phenyleneterephthalamide) Pound-for-pound Kevlar is five times stronger than steel and thus provides for a lightweight and high strength material in an application where maneuverability and high impact resistance are essential. High elastic modulus- 83Gpa Tensile strength- 3.6 Gpa Breaking strength 338 N Kevlar fibers are made for the bests by spinning individual strands of Kevlar together to make a stronger rope-like structure. This process is called aramid weave. CAS #- 24938-64-5
Thermally stable: Decomposes at 450°C, no embrittlement as low as -196°C. Slightly negative axial coefficient of thermal expansion. Impurities can weaken the material, esp. Calcium, which is used in processing Degrades at exposure to UV light, bleach, dry-cleaning agents, and repeated washing Kevlar is expensive to produce due to using concentrated sulfuric acid, used to keep the polymers in solution during spinning process. Produced in a condensation reaction that yields hydrochloric acid.
Uses of Kevlar Uses of Kevlar Kevlar 29 is used in body armor, brake pads, and asbestos replacement Kevlar 49 is used in boat hulls and bicycle frames Kevlar can also be used in shelters to protect against tornadoes, and it can also deflect large projectiles going up to 250 mph For a typical armor vest: Heavy ceramic plates made of boron carbide Layer of kevlar holds plate together when impact breaks the ceramic As the importance of adequate body armor becomes more obvious, the number of law enforcement officials and troops equipped with this armor will continue to increase. DuPont announced a $500 million investment into a Kevlar production facility in Charleston, SC,
Success in application due to high modulus of elasticity (can be shaped without breaking) and high strength (resists penetration, absorbs impact well) Environmental Concerns Thermoset polymer – non-biodegradable and non- recyclable Benefits out weigh the cost for disposal Since its development, countless lives have been saved when being used as protective surfaces.