Page 2 :
be polymerised for example, ethene. A, monomer on polymerisation produces a ther, , moplastics material. Thermoplastics soften, on heating. Examples of thermoplastics are, , Polyvinyl Chloride (PVC) and Polystyrene., There are other polymers which once set in a, , of, , purposes, , where, , high strength fibres, , are, Are, , required such as fishing nets, ropes,, parachute fabrics and tyre-cord. It is also, mixed with wool to make long lasting fabrics, , Nylon is widely used as a plastic for making, machine parts., , given shape on heating cannot be softened or, POLYESTER, , melted on being reheated. These irreversible, polymers are called Thermosetting Polymers., Two examples of, polymers, , bakelite, , thermosetting, , compound with two hydroxyl (-OH) groups, , (Phenol formaldehyde) and, , with a compound containing two carboxylie, acid groups (-COOH). The reaction between, , SYNTHETIC FIBRES, , the hydroxyl and carboxylic acid groups, , melamine (melamine formaldehyde)., , syntheticfibres are polymers comprising, , of one or more carbon compounds repeating, , themselves to form very large molecules. Poly, means, , Polyester is made by reacting a carbon, , many', , and, , mer means a, , unit. Cellulose is a naturally, , 'repeating, occurring, , polymer. The walls of all plants cells are made, of cellulose. Wood contains a large amount, of, this natural polymer. Paper is purified form, , ofcellulose. Cotton andjute are natural fibres, made of cellulose., , RAYON, , Rayon is man-made material which con-, , sists of purified cellulose in the form of long, fibres. It is made from paper strips dipped in, cold sodium hydroxide solution to further, , purify the cellulose and then treated with, , results in the formation of an easter group, (-CO0-). Since the fibre contains many ester, groups, it is called Polyester., , Polyester fibres like nylon absorb very, , little water. The fibre retains crease and lasts, for along since., , FERTILIZERS, The chemical substances which are, added to the soil during sowing season to, avoid starvation of plants, to promote their, healthy growth and to make up the deficiency, of essential elements, are called fertilizers., , Chemical fertilizers may be of the follow, , ingtypes:, , carbon disulphide to form a cellulose solution., , Nitrogenous Fertilizers, Those fertilizers which mainly supply, , This solution is allowed to pass through fine, , nitrogen to the plants., , pores in metal eylinders, into a dilute solution, , of sulphuric acid. This results in the formation, of long fibre cellulose known as viscose rayon., Rayon fibre is chemically identical to cotton, but has a shine like silk. Rayon is used on a, large scale in India for making textiles tyre-, , cord, carpets and surgical dressings., , NYLON, Nylon was made by polymerisation of, small organic molecules not found naturally., The material so made is melted and, spun into, , fibres or cast into desired shapes. Nylon was, , the first synthetic fibre made by man., Nylon, was first made in 1935 and, commercially, marketed in 1939 as stockings for women., , Sixty-four million pairs of stockings were sold, in the first year. Today it is used for a variety, , Examples of nitrogenous fertilizers are :, , ) Urea: NH2CONH2, (i) Ammonium sulphate: (NHa)2S04, , (ii) Calcium ammonium nitrate (CAN):, , Ca(NOs)2.NH4NO3, iv) Nitrolim, , or, , CaCN2+C, , calcium cyanamide, , Phosphatic Fertilizers, , These fertilizers, phorus to the plants., , mainly supply phos, , Examples of phosphatic fertilizers are:, i), , Superphosphate of lime:, , Ca(H2PO4)2.H20 +2(0CaSO4.2H20), i) Phosphatic slag (or Thomas Meal, , Gii) Triple superphosphate Ca(HoPO43

Page 3 :
Mixed or NPK Fertilizers, These, , proportions, , are, , obtained by mixing nitrogenous, phosphatic, therefore named NPK fertilizers., , and are, , and potash fertilizers in suitable