SYNTHETIC FIBRES AND PLASTICS Introduction The clothes which we wear are made of fabrics. Fabrics are made from fibres obtained from natural or artificial sources.EX- natural fibres- Obtained from plants :Wool, silk, cotton,synthetic fibres-made by human beings: polyesters, terylene What are Synthetic Fibres? A synthetic fibre is a chain of small units joined together.Each small unit is actually a chemical substanceMany such small units combine to form a large single unit called a RAYON (also called artificial silk ) It is cheaper than silk and can be woven like silk fibres.It is made from cellulose obtained from wood pulp.It can also be dyed in a wide variety of colours.It is used to make carpets , bed sheets etc. Nylon It is prepared from coal, water and air.It was the first fully synthetic fibre.Nylon fibre is strong, elastic and light.It is lustrous and easy to wash.It is used to make socks, ropes, tents, toothbrushes, car seat belts, sleeping bags, curtains, parachutes and ropes for rock climbing . POLYSTER A versatile man-made fabric.It has an outstanding characteristic of resisting wrinkle.It is strong and soft.Ex: TeryleneIt is used in dresses, suits, rainwearPET (polyethylene terephthalate) is a very familiar form of polyester.It is used for making bottles, utensils, films, wires and many other useful products. ACRYLIC A fibre similar to that of wool and is used to make sweater, blankets, shawls, etc.It is lightweight, soft and warm.It is cheaper than natural wool.It is resistant to chemicals, moths and sunlight. Characteristics of Synthetic Fibres They are durableThey dry up quicklyThey are less expensiveThey are readily availableThey are easy to maintain. Plastics Like synthetic fibres, plastic is also a polymer.Some plastics have a linear arrangement of the units and some have a cross-linked arrangement of the units.Example: Polythene.Plastic is easily mouldable i.e. can be shaped in any form.Plastic can be recycled, reused, coloured, melted, rolled into sheets or made into wires. Thermoplastics : plastic which gets deformed easily on heating and can be bent easily. Ex: Polythene and PVCUses: manufacturing toys, combs and various types of containers Thermosetting plastics: plastics which when moulded once, can not be softened by heating.Ex: bakelite and melamine.Bakelite is a poor conductor of heat and electricity.It is used for making electrical switches, handles of various utensils, etc.Melamine is a versatile material.It resists fire and can tolerate heat better than other plasticsIt is used for making floor tiles, kitchenware and fabrics which resist fire. Characteristics of Plastics: Non-reactive: Not affected by air, water, soil, etc. Light, strong and durable: Light, strong and durable and can be moulded into different shapes and sizes. Poor Conductors: Do not allow heat and electricity to flow through them. Effect of Plastics on Environment: Natural materials like wood and paper are biodegradable (bio = living; degeradable = able to broken down).In contrast, most plastics do not decay, therefore, they are non-biodegradable.The lightweight nature of plastics can also be a problem.Burning of plastics also release poisonous fumes into the atmosphere thus polluting the environment. We need to use synthetic fibres and plastics in such a manner that we can enjoy their good qualities and at the same time minimise the environmental hazards for the living communities.