Synthetic Fibres and Plastics - I

Cotton, wool and silk fibres are obtained from cotton plant, sheep and silkworm, respectively. It means that they are obtained from natural sources. But, nylon is synthesized by the use of chemicals. Hence it is not a natural fibre.

Rayon or artificial silk is used to make bed sheets and carpets by mixing it with other natural fibres, like cotton and wool. It can take up a variety of colours. Silk is a naturally obtained fibre and is not obtained by mixing rayon with wool.

Swimwear has nothing to do with the strength of fibre or its warmth. Swimwear should have an easy contact with water and it should also get dried up quickly. Nylon possesses dip and dry property, therefore it is used to make swimwear.

The most essential characteristic for selecting a material for making parachutes and ropes for rock climbing is its high tensile strength. Nylon fibres are stronger than even a steel wire and have very high tensile strength. Therefore, it is used for making parachutes and ropes.

The fibre used for making cloth should have certain characteristics like it should be light in weight and should not have a dull surface, i.e. should be shiny/lustrous. It should be strong/durable and should possess some elasticity. These characteristics make nylon fibre a suitable choice for making cloth.
High tensile strength, easy moulding and being a regenerated fibre are also the characteristics of nylon, but these are not the requisite properties for using it make cloth.

Umbrella is used to protect oneself from rain. It means that it should soak less water and should get dried up easily. Synthetic fibres possess the characteristic properties of soaking less water and getting dried up easily. Therefore, they are used for making umbrellas.

Plastics are very useful but they do not get decomposed by microbial action, which causes many problems. It means that they are non-biodegradable substances.

Non-stick coating on cookware should be made of such a material that neither reacts with oil nor allows the oil to stick over it. Teflon possesses both these properties. That is why it is used for coating cookware.

Both thermosetting plastics and thermoplastics have almost the same tensile strength and durability.
Both thermosetting and thermoplastics are non-biodegradable but thermoplastics can be recycled but thermo setting plastics cannot.
The main difference between the two is that thermosetting plastics once set cannot be moulded again, but thermoplastic can be remoulded on heating. 

Bakelite is a poor conductor of both heat and electricity. So, it is used to make switches and utensil handles. 

Polymer is a compound having a high molecular mass and is made up of many small repeating units called monomers. Nylon, acrylic and silk  are polymers. However, amino acids are monomers of proteins.

Acrylic is a synthetic fibre but silk and wool are natural.

Melamine is used to make floor tiles, kitchenware and fabrics which resist fire.