Wednesday, 20 January 2016

Science Notes # 8

(Source: VIII NCERT Science Chapter 3)

- Cotton, Wool, Silk are examples of natural fibres.

- Cotton is a polymer of cellulose.

- Rayon is artificial silk obtained by chemical treatment of wood pulp.

- Rayon is mixed with cotton to make bed sheets.

- Rayon is mixed with wool to make carpets.

- Nylon is first fully synthetic fiber.

- Nylon was prepared from coal, water and air.

- Nylon is used for making parachutes and ropes for rock climbing.

- A nylon thread is stronger than steel wire.

- Polyester fabric is wrinkle free.

- Terylene is a popular polyester.

- Polyester (PET) used for making bottles, utensils, films, wires etc.

- Acrylic is used to make sweaters, shawls.

- Polythene is an example of a plastic.

- Plastic which gets deformed easily on heating and can be bent easily are called thermoplastics.

- Plastics which moulded once cannot be softened by heating are called thermosetting plastics. eg. Bakelite and Melamine.

- Bakelite is poor conductor of heat and electricity. It is used for making switches, handles of utensils.

- Melamine can resist fire. It is used for making tiles, Kitchenware.

- Teflon is a special plastic on which oil and water do not stick.