Category Polymers

           There are metals that can resist bullets. But it would be difficult to carry bulletproof vests made of metals. The more convenient option is a lighter, strong fibre which will prevent the bullets from hitting your body and easy to wear at the same time. And that is why Kevlar is used for this purpose.

           Kevlar is one of the strongest materials on earth; when it is woven into fabric, it is five times stronger than steel. It can even resist knives. Kevlar has a strong ring-like structure and can resist high temperatures. It is used for making many types of body armour.

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           Both nylon 6 and nylon 66 are durable polymers. Their properties differ based on how the monomers are bonded.

           Monomers of caprolactam from nylon 6.  The monomers have 6 carbon atoms each. On the other hand, nylon 66 has two types of monomers – hexamethylenediamine and adipic acid. The repeating units have twelve carbon atoms. Nylon 6 is formed through a complex reaction called ring opening polymerization, while nylon 66 is formed through condensation polymerization.

           Nylon 6 has high strength and is very flexible. So, it is used to make things like gears, ropes, bearings and other parts of cars. Nylon 66 is rigid and is also resistant to heat and chemicals. Therefore, it is used in the textile industry to make garments and carpets.

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           Would you believe it if someone tells you that there were riots in the name of a polymer? Well, be ready for surprises. Nylon riots were real! It happened in the US after the Second World War.

           Du Pont started making nylon stockings towards the end of the 1930s which drove American women crazy. Stockings were highly sought-after hosiery. Around four million stockings were sold in a day. During the war years, the silk export from Japan ceased and there was a shortage of nylon, as it was used to make war materials like parachutes and tents. Nylon stockings were produced no more. This created a shortage. It was so fashionable; black markets sold a few at high prices and many women resorted to paint their legs like transparent nylon stockings!

           After the war, nylon stockings reappeared in the markets. Hundreds of women lined up in the stores to get hold of limited nylon stockings. The shortage of stockings led to a series of disturbances in the US that occasionally broke into fights. Women flooded the stores knocking down shelves, and fighting hammer and tongs for the limited stock. The situation became terrible in Pittsburgh when 40,000 women lined up for 13,000 pairs of stockings.

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           Can you name some products made of nylon? Apart from toothbrushes, a range of other products like fishing nets, fabrics, stockings, machine screws, gears, ropes, parachutes, tents, wind cheaters, hammocks, seat belts and sleeping bags use nylon.

           Stockings were the first successful product made of nylon. There was a craze for nylon stockings in the World War II era.

           Nylon is strong, light, elastic and lustrous. It is easy to wash and while washing, nylon does not stretch or shrink. It retains shape and dries quickly. Because of these reasons, nylon is usually preferred to make garments.

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          Nylon would not be possible if not for a company named Du Pont and a scientist called Wallace Carothers. Remember Staudinger, the father of polymer chemistry? His research sparked the interest of chemists and paved way to more and more discoveries in polymers.

          Many chemical companies worked day and night to form new fibres that would create a revolution in the market. Du Pont was one among them. This American company worked to explore the commercial applications of polymers. Wallace Carothers joined Du Pont around the same time.

          Wallace could create tiny fibres in a test tube when he experimented with amine, hexamethylenediamine and adipic acid. But, the presence of water restricted the formation of long fibres. He tried removing water obtained in the reaction and guess what? He could make long fibres through a process called cold drawing. Thus, a new polymer took birth and was named nylon. This happened in the 1930s.

          Nylon was brought into the market in the 1940s. A crisis of natural fibres came along with other hardships of World War II. Chemists tried to develop a new fabric that could provide an alternative for natural clothing. Rayon was already discovered. Nylon too provided a cheap alternative and became a huge success in the market.

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           All of you use your toothbrush at least once a day. But, have you ever thought about the polymer used to make the bristles that clean your teeth every day?

           The bristles of a toothbrush are made of nylon. Nylon is a thermoplastic with a silky texture. It is a polyamide with a backbone made of amide monomers. Because of the hydrogen bonding between the monomers, nylon’s backbone is symmetrical.

           Nylon is resistant to biological and chemical agents. Imagine what would happen to your toothbrush if it reacted with saliva. It also resists abrasion to an extent; it won’t wear off due to rubbing. However, nylon degrades in the presence of UV light.

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           Bakelite is a thermosetting plastic which shows high resistance to heat, electricity and chemical agents. It can be easily moulded into any shape and dyed into any colour. It is widely used to make insulating bushes, sockets for electric bulbs and other non-conducting parts of electrical appliances because of the electrical insulation it provides.

           It is used to make scores of products like clocks, radios, telephones, kitchenware, tableware, jewellery boxes, pipes, buttons, cameras, lamps, chess sets, billiard balls, and jewellery. Moreover, it is cheap and affordable. No wonder, it is called a material of thousand uses.

           Bakelite changed the trends in fashion too. Bakelite jewellery was highly sought-after in the 1920s as it offered an affordable and attractive replacement for other materials. It also played a role in World War I and II as it was used to make a lot of war materials.

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           Leo Baekeland started working with polymers to make money and he did make a lot of money, even before he discovered the first synthetic plastic. By then, he had already developed Velox photographic film, which made him rich.

           He later devoted his efforts to develop a substitute for shellac, a resin obtained from the shells of Asian lac beetles.

           After a lot of trials and errors, he finally succeeded in making a resin from phenol and formaldehyde, thus making the first ever synthetic plastic. It was cheaper than celluloid and had better properties. This thermosetting material could be easily moulded into different shapes as well. He called this substance ‘bakelite’.

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           Apart from resembling ivory, celluloid has other amazing properties as well. Celluloid is a permanent, hard solid at normal temperatures and when heated, it becomes soft and could be moulded or rolled into sheets. Because of these, it was used to make a wide range of products.

           By the 1880s, celluloid was used as a substitute for linen. It was used to make detachable collars and cuffs for men’s clothing. Photography wouldn’t have been possible if not for celluloid. 1n1882, John H. Stevens discovered that celluloid could be diluted using amyl acetate. He was working as a chemist at the Celluloid Manufacturing Company then.

           Diluting celluloid produced a clear, flexible film. Researchers like Henry Reichenbach of the Eastman Kodak Company further processed it into film for still photography. It was later used to make motion pictures.

           These films were inflammable and would discolour with age. But they remained the medium for motion pictures till the invention of cellulose-acetate safety film in the 930s.

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