Copia - History of Kevlar

History of Kevlar

Kevlar was discovered in 1965 by a research team at DuPount de Nemours, its discovery was an accident, when while creating a new type of hight temperature resistant tire they synthesized strong and lightweight polymer, which was named Kevlar. Kevlar is produced throught a spinning process in which a polymer of para-phenyle terephthalamide is extruded into a highly concentrated sulfuric acid solution, forming a stiff and strong fiber.

Chemical composition

Kevlar's chemical structure consists of several repeating interchain bonds. These chains are cross-linked with hydrogen bonds, providing tensile strenght 10 times greater than steel at the same weight.

The structure of polymer

A particular class of polyamides, called polyaramides,obtained from aromatic diamines and aromatic acids, presents in their molecular structurebenzene rings and amide group. Kevlar is a condensation polymer, in fact when we create the polymer it release water. In this polymer there are benzene rings, with the presence of nitrogen, hydrogen and oxygen. The hydrogen bonds build the branching of the polymer.

Chemical-Physical Charateristics

Kevlar's chemical structure consists of several repeating interchain bonds. These chains are fully extended and perfectly aligned within the Kevlar fiber and cross-linked with hydrogen bonds, providing strong tensile strength and a strong protective barrier against tears, cuts and penetration.

Il kevlar is also flame resistant, protecting against thermal hazards up to 800 degrees Fahrenheit. Additionally, Kevlar fibers do not melt, drip, or promote combustion.

Physical and chemical properties of kevlar make it able to whitstand: traction, bullet, heat, cut and perforation.

disposal

Kevlar is a substance that is very resistant to high temperatures and impacts. Kevlar is not biodegradable and is very difficult to dispose, because it releases toxic substances during incineration and disposal in landfills. In these cases it is reused to create other objects.

History of teflon

Teflon was discovered in 1938 during an attempt to manufacture a new chlorofluorocarbon for use as a refrigerant for compression cycles. During the measurement of a gas flow rate, it was noticed that its flow rate stopped before the scale indicated the tetrafluoroethylene cylinder as empty. Once the cylinder was opened, it was noticed that an extremely slippery and substantially insoluble waxy coating had formed on the internal walls. The chemical analyzes carried out confirmed that it was polytetrafluoroethylene.

Chemical composition

The chemical name of the Teflon is- 1,1,2,2 tetrafluoroethylene and has a chemical formula of (C2F4)n. The chemical formula tells about the structure of the molecule that contains a repetitive chain of C2F4 unit groups.

Structure of polymer

PTFE is a linear polymer, meaning its molecules are made up of long chains of carbon atoms linked together by single bonds. Each carbon atom is linked to two fluorine atoms.

Chemical-Physical Characteristics

1) Chemically inert: The presence of fluorine atoms prevents PTFE from reacting easily with most chemical reagents, making it highly resistant to corrosion. 2) Heat resistance: PTFE is stable even at high temperatures, with a melting point of up to 327°C. 3) Low adhesion: The fluorine-based structure gives Teflon a very slippery surface, making it particularly useful as a non-stick coating, for example in pans. 4) Abrasion resistance: It is resistant to wear and scratches, making it suitable for industrial applications and in contexts where long life is required. 5) Electrically insulating: It is an excellent electrical insulator, which is why it is also used in electrical cables.

Physical and chemical properties of teflon make it able to whitstand: cooking, chemical industry, automobiles, electronics, and medicine and biotechnology

disposal

Recycling PTFE involves two different processes with two different end results. One involves irradiation of the PTFE scrap to heavy dose of ionizing irradiation which will reduce its molecular weight. On pulverizing, the irradiated PTFE scrap turns into micro powder which finds certain applications. The second method involves pulverizing the PTFE scrap without irradiation so that it becomes reusable like virgin PTFE itself.

website

• chimica online
• Wikipedia
• Intechopen.com
• rtprototype.com
• testbook.com
• Prodotti Kevlar
• Prodotti Teflon
• DuPont Italia