Kevlar
As Bulletproof Vest Material
Bulletproof vests are protective clothing
to minimize bullet injury. Usually used by military and police personnel in
certain tasks. Materials for bulletproof vests include metal (steel or
titanium), ceramic or polymer type which can provide extra protection against
the vital parts of the wearer.
This vest protects the wearer by holding
back the bullet. The bullet is stopped before penetrating into the body. When
the vest holds the bullet penetration, the drive from the bullet is reduced by
spreading its momentum throughout the body. Users will still feel the kinetic
energy of the bullet, this can cause bruises, swelling or serious internal
injuries.
One of the polymers developed as a modern
anti-bullet vest material is kevlar. Kevlar is also known as twaron and
poly-paraffenylene terephthalamide, a synthetic fiber whose strength is five
times the strength of copper, of the same weight. Kevlar is extremely resistant
to heat and decomposes above 400 oC without melting. Kevlar was invented by the
DuPont company in the early 1960s, the work of Stephanie Kwolek. Kevlar is a
registered trademark by E.I. De Pont de Nemours and Company.
Properties
Kevlar is one type of
aramida, which consists of long chain polymers with parallel orientation.
Aramide itself is a synthetic fiber in the form of a long chain of synthetic
polyamides with at least 85 percent of its amid link attached directly to two
aromatic chains (amide groups and alternating aromatic groups). Kevlar strength
is obtained from intra-molecular hydrogen bonds and interaction of aromatic
powders between sheets. These interactions are stronger than the interactions of
Van der Waals contained in other synthetic polymers and fibers such as dyneema
(fibers made from very long polyethylene chains, arranged in the same
direction). The presence of other salts and impurities, usually calcium, may
interfere with the interaction of polymer sheets and must be eliminated in the
production process. Kevlar consists of relatively rigid molecules, which form
structures such as flat sheets on silk proteins.
Of these properties obtained fiber with high
mechanical strength and heat resistance.
Kevlar has free groups
that can form hydrogen bonds on the outside, so they can absorb water and have
good 'wet' properties. It also makes it feel more natural and 'sticky' compared
to polymers in general, such as polyethylene.
The main weakness of kevlar is that it can decompose
under alkaline conditions or when exposed to chlorine. Although it can support
large tensile stress, kevlar is not strong enough under compressive pressure.
To overcome this problem, kevlar is often used in conjunction with strong
materials against compressive pressures.
Production
Kevlar is synthesized
from monomers 1, 4-phenyliamylamine (para-phenylenediamine) and terephthaloyl
chloride. The result is an aromatic amido polymer (aramide) with a benzene ring
and an alternating amide group. With this production step, randomly assembled
polymer sheets are produced. To make kevlar, the materials are dissolved and
stirred, resulting in a fiber-oriented polymer chain.
Kevlar is expensive
because of the difficult use of concentrated sulfuric acid in its production.
This extreme condition is required to maintain the high polymer toxicity in
solution during synthesis and stirring.
DSM's Dyneema, Akzo's
Twaron, Toyobo's Zylon (controversial, recent study, the material is rapidly
degraded so that the wearer is not as protected as expected), or Honeywell's
GoldFlex - all trademarks. The new materials are lighter, thinner, and more
resistant than kevlar, but the price is more expensive. (Reader: From various
sources).
Literature:
what is meaning of kevlar?
BalasHapusKevlar is a registered trademark for synthetic aramid fiber fibers, this material is still in contact with Nomex and Technora. Poly-paraphenylene terephthalamide / Kevlar was created in 1965 by Stephanie Kwolek when she worked at DuPont. Furthermore, this material was developed by DuPont company. This powerful material was first used commercially in the 1970s as a substitute for steel in tire products for racing purposes. This material is widely used on tires and ship screens to materials for the manufacture of bulletproof vests, this is due to the strength and elasticity of the material and the light weight that is the nature of this material. This material is touted as a material that is five times stronger than steel of the same weight.
HapusWhether to make household appliances using kevlar?
BalasHapusI thought it might be just a very heavy kevlar so not used for household purposes. Besides kevlar made of carbon. But carbon fiber (kevlar) proved to provide a very significant benefit for human life. One of them in the manufacture of bulletproof vests. This vest is made of steel or titanium type of metal, ceramic or polymer type which can provide extra protection against the vital parts of the wearer. Kevlar also known as twaron and poly-paraffenylene terephthalamide was created by Stephanie Kwolek, an inventor from Kensington, Pennsylvania, USA.
HapusKevlar is synthesized from monomers 1, 4-phenyliamylamine (para-phenylenediamine) and terephthaloyl chloride. Would you like to tell isomer that?
BalasHapusI think it is not a type of isomer because Monomer is a polymer constituent. They can be simple or complex molecules with double bonds or other functional groups such as -OH, -NH2, -COOH, etc. of unsaturated double bonds or functional groups required in the polymerization process, when some monomers are connected to form polymers.
Hapus"The new materials are lighter, thinner, and more resistant than kevlar, but the price is more expensive" Are there any links to the compounds used?
BalasHapusYes, the excess kevlar compared to other carbon compounds is Kevlar also known as twaron and poly-paraffenylene terephthalamide, which is a synthetic fiber whose power is five times the strength of copper, with the same weight. Kevlar is extremely resistant to heat and decomposes above 400 oC without melting.
HapusWhy the presence of salt and other impurities, usually calcium, can interfere with polymer sheet interactions and should be eliminated in the production process?
BalasHapusThese interactions are stronger than the interactions of Van der Waals contained in other synthetic polymers and fibers such as dyneema (fibers made from very long polyethylene chains, arranged in the same direction).
HapusSo salt salt is easy to react and interfere with other reactions
What the component of kevlar?
BalasHapusKevlar is synthesized from monomers 1, 4-phenyliamylamine (para-phenylenediamine) and terephthaloyl chloride. The result is an aromatic amido polymer (aramide) with a benzene ring and an alternating amide group. With this production step, randomly assembled polymer sheets were obtained. To make the kevlar, the materials are dissolved and stirred, resulting in a fiber-oriented polymer chain forming the fibers.
HapusKevlar used as a bullet vest material other than kevlar used as what?
BalasHapusAramid (Kevlar)
HapusThis material was discovered by Stephanie Kwolek in 1964, an American chemist, who worked as a researcher at the DuPont company. Aramid is an acronym of the word aromatic polyamide. Aramid has a strong structure, tough, has a good damping properties (vibration damping), resistant to acid (acid) and base (leach), but it can withstand heat up to 370 ° C, so it is not flammable. The marketed product is known as Kevlar. Kevlar has a light weight, but 5 times stronger than iron.This material is widely used on tires and ship sails up material for the manufacture of bulletproof vests, this is due to the strength and elasticity of materials and light weight which is the nature of this material. This material is touted as a material that is five times stronger than steel of the same weight