atm ( ) n Polythene ethene It is used as insulation for cables, making toys etc… HDPE The polymerization of ethylene is carried out at 373K and 6to7 atm pressure using Zeiglar – Natta catalyst TiCl +(C H ) Al [ ] HDPE has high density and melting point and it is used to make bottles, pipe etc.., Preparation of Teflon (PTFE) The monomer is tetrafluroethylene. When the monomer is heated with oxygen (or) ammonium persulphate under high pressure, Teflon is obtained. n CF = CF CF CF ( ) n It is used for coating articles and preparing non – stick utensils. I.
Preparation of Orlon (polyacrylonitrile – PAN) It is prepared by the addition polymerisation of vinylcyanide (acrylonitrile) using a peroxide initiator. n (CH = CH) CN Peroxides CH ( ) n CN PAN Prop - -enenitrile It is used as a substitute of wool for making blankets, sweaters etc… XII U15 Chemistry in XII U15 Chemistry in - - - - Condensation polymerisation Condensation polymers are formed by the reaction between functional groups an adjacent monomers with the elimination of simple molecules like H O, NH etc…. Each monomer must undergo at least two substitution reactions to continue to grow the polymer chain i.e., the monomer must be at least bi functional. Examples : Nylon– , , terylene….
Nylon – , Nylon – , can be prepared by mixing equimolar adipic acid and hexamethylene – diamine to form a nylon salt which on heating eliminate a water molecule to form amide bonds. HO (CH + H N (CH NH (CH NH (CH NH hexan - , - dioicacid hexan - , - diamine (CH ) NH (CH NH (CH NH * (CH NH...... ..... n Nylon salt Poly (hexamethyleneadipamide) Nylon , It is used in textiles, manufacture of cards etc… Nylon – Capro lactam (monomer) on heating at 533K in an inert atmosphere with traces of water