My Science School

           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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           All polymers that are obtained from nature are known as biopolymers and they have several features that are eco-friendly. There are also man-made biopolymers that retain the properties of natural biopolymers. Biopolymers are renewable and sustainable.

           Biopolymers reduce the amount of carbon dioxide in the atmosphere. They are biodegradable; they can be broken down to carbon dioxide and water by microorganisms. Most of them are compostable as well. Thus, the chances of them polluting the environment are very less. Due to this, they are produced in large quantities and used for the production of plastics.

           Based on their structure, biopolymers can be classified into three - long nucleotide polymers called polynucleotides, short polymers of amino acids called polypeptides and linear chains of carbohydrates called polysaccharides.

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           Before the discovery of erasers, wet bread crumbs were used widely for erasing. Imagine going to school with a packet of wet bread-crumbs. It would be funny.

          Edward Nairne, a British engineer once made a mistake while writing. He accidentally took a piece of rubber instead of bread crumbs to erase it and guess what? Rubber proved to be a better eraser. Thanks to Nairne’s mistake our school life has become easier. Every time you rub out your mistakes without a trace, just remember that your eraser was an accidental discovery.

           Joseph Priestley was the first one to discover the erasing properties of rubber, but Edward Nairne was the first to develop and market it.

            An eraser gets its common name ‘rubber’ from the rubbing action. It works chemically, pretty much like a sticky magnet. When it is rubbed over the writing, the graphite particles stick to the rubber, making erasing possible.

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           Have you heard of Goodyear tyres? Goodyear is a leading tyre manufacturer in the world. This American company was named so to commemorate Charles Goodyear, an American chemist and manufacturing engineer, the man who found out that rubber could be strengthened by the process of vulcanization.

           Before vulcanization was discovered, people found it difficult to make useful products out of rubber. Rubber would get sticky at high temperatures and harden in cold climates. Goodyear accidentally dropped a piece of rubber in sulphur and he discovered that it became more stable and flexible afterwards due to some chemical change. It had more strength than before. Since then, rubber is treated with sulphur to enhance its desirable properties and this chemical treatment is known as vulcanization.

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          There are millions and millions of microorganisms around us which thrive in a variety of conditions. Some of these microorganisms play a part in the synthesis of polymers. Wonder how?

           Some microorganisms can live in extreme conditions. There are some thermal resistant bacteria that can withstand temperatures as high as 350 degrees Celsius and they are used in chain growth polymerization. It is a mechanism of polymerization in which monomers get added to a growing polymer chain. Some of these microorganisms are also used in the production of medicines.

           Apart from this, there are millions of tiny creatures in the sea that sink into the seabed when they die. Calcium carbonate is a common inorganic substance found in organisms that do not easily decompose. It piles up in the seabed and forms huge deposits of chalk and lime with the passing of time which is later used for making useful polymers like plastic and polyvinyl chloride.

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               Cartilage is a soft, yet firm tissue which performs some important functions in our body. It’s a flexible tissue found in the joints that connects bones. It also helps in the formation of bones. Cartilage too is a polymer.

               Cartilage is a protein made of amino acids. It is not only present in human beings, but also in other animals and some fishes. A fish with cartilage is commonly known as cartilaginous fish. Cartilage is tough, flexible and provides enough structural support.

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