What+is+the+structure+of+bulletproof+fabrics?

Marco Napoleone

**__ What is the structure of bulletproof fabrics? __** -Most bulletproof fabrics or body armours have a certain factor in common, the use of KEVLAR® -KEVLAR®, created by Stephanie Kwolek and Herbert Blades in 1965 for the DuPont Company , is a man-made organic fibre and a polyaromatic amide - This means that it contains aromatic and amide groups - Other polymers with a high breaking strength often contain one or both of these molecular groups - Kevlar® is created through the weaving of a liquid into a solid, called aramid weaving - Aramid fibres tend to be difficult to corrode, resistant to heat, and have no melting point. Aramid fibres like Kevlar® may be slightly corrosive if exposed to chlorine - When the molten KEVLAR® is spun into fibres, the polymers have a crystalline arrangement - With the polymer chains oriented parallel to the fibre’s axis, the polar amide groups are able to form hydrogen bonds between the adjacent polymer chains, basically acting like glue holding the separate polymer chains together -The aromatic components of KEVLAR® polymers have a radial (spoke-like) orientation -This gives a high degree of symmetry and regularity to the internal structure of the fibres - The crystalline-like regularity is considered to be the largest contributing factor in the strength of KEVLAR® - KEVLAR®’S unique combination of properties means it can be used in a wide variety of industrial applications - KEVLAR® consists of fibres made from long molecular chains - These molecular chains are produced from poly-paraphenylene terephthalamide - The chains are highly oriented with strong interchain bonding which is why they have a unique combination of properties -Some of the general features of KEVLAR® are: - When a handgun bullet strikes body armour, it ends up getting caught in a "web" of very strong fibres -The bullet not only stretches the fibres it hits, but others that are in contact with them and the ones that those pull - These are the fibres that comprise KEVLAR® - The fibres absorb and disperse the impact energy that hits the **bullet proof fabric (usually a vest)** from the bullet, causing the bullet to deform into a mushroom-like shape - Energy is absorbed in the material of the bullet proof vests, layer by layer until the bullet has been stopped - Because the fibres work together both in the individual layer and with other layers of material in the vest, a large area of the **bullet proof vest** becomes involved in preventing the bullet from getting through - This helps in dissipating the forces which can cause injuries (commonly referred to as "blunt trauma") to internal organs - In 2008, DuPont developed a new type of KEVLAR®, called KEVLAR® XP (exceptional performance) - This new KEVLAR® is able to stop bullets from a .44 Magnum in just the first 3 out of 11 layers, allowing for a reduced blunt trauma effect felt by the victim
 * High tensile strength at low weight
 * Low elongation to break
 * High modulus (structural rigidity)
 * Low electrical conductivity
 * High chemical resistance
 * Low thermal shrinkage
 * High toughness (work-to-break)
 * Excellent dimensional stability
 * High cut resistance
 * Flame resistant, self-extinguishing

__**Sources**__

Anonymous (2006, April 01). Body Armour - Technological Issues. Military Technology, (4), 72, Retrieved from http://elibrary.bigchalk.com

Kanable, R. (Oct 2008). Kevlar technology: designed to defeat today's threats. Law Enforcement Technology, 35, 10. p.68(7). Retrieved November 2, 2010, from General OneFile via Gale: http://find.galegroup.com/gps/start.do?prodId=IPS&userGroupName=ko_k12pr_d63

Arndt, M. (2006, August 07). Body Armor Fit For a Superhero. Business Week, 76, Retrieved from http://elibrary.bigchalk.com