POLYMERSCLASSIFICATION OF POLYMERSTHEORY 1 CLASSIFICATION OF POLYMERS I] Homopolymers II] Copolymers They are obtained by a large They are obtain by a two or moreNumber of same monomer.number of differentmonomer. i)LinearHomopolymeri)Linearcopolymerwith randomly joined monomer. - A A A A A A -- A A B A B B ii) Branched Homopolymerii) Linear copolymer with alternately joined monomer. A A - A B A B A B - -A A A A- A A - iii) Linear copolymer with block A A way joined monomer. A- A A A B B A A A B B- III] Cross-linked polymers They are obtained by using polyfunctional monomer. It contains a largemolecule.Hencetheyarehard,strong,brittle&donot soften on heating. Trifunctional + Bifunctional --- Cross linked polymer Eg. Backlite (O,P dimethylolphenol monomer is used) POLYMERSCLASSIFICATION OF POLYMERSTHEORY 2 IV] Organic polymersV] Inorganic polymers ThepolymerchainconsistsofThepolymerchain contain other mainly carbon atom. than carbon atom.Eg. P.V.C, Polyethelene,eg. Polysilane, Silicon polymer. Polyesters,DNA-RNA, etc. TYPES OF POLYMER On the basis of origin polymers have following types. i) Natural polymerii) Synthetic polymer. iii) Semi. It is obtained It is obtained byIt is obtained by naturally. synthetically modification of(by natural polymer chemical reactions) eg.Cellulose,eg.Polyesters,nylons,eg.Cellulose acetate, Proteins,Phenolformaldehyde.Cellulose nitrate,DNA-RNA.Ureaformaldehyde.Vulcanized natural rubber. POLYMERSCLASSIFICATION OF POLYMERSTHEORY 3 TYPES OF POLYMERIZATION Addition polymerizationCondensation polymerization Inthistypewecanused unsaturated monomer. Eg.Ethylene,propylene, vinylchloride,styrene, butadiene, etc. Inthistypemonomermust contain functional group. Eg.OH,-COOH,-NH2,-COOR, --COCl, etc. For polymerization there is a need of initiator ie. Catalyst. Eg.FreeradicalorIonic initiator. Catalyst mayor maynotbe used. Reactionsinvolvethree steps.ie.Initiation,chain propagation&chain termination. Reactionisstepwise(one step). i.e.Monomerreactsoneby one. Itisexothermicreaction. Hencecoolantisuseas tempcontroller.Howeverto triggerthereactionslight heating is necessary. Thisreactionisalways endothermic. Hence there is no need to control the temp. Reactionrequireshigh temperature. Overallreactionisvery slow. Overall reaction is very fast. Thereisnoformationof byproduct. There is formation of simple byproductlikeH2O,R-OH, NaCl, etc. Eg.Polyethylene, polypropylene, etc. Eg. Amide linkage (-CO-NH-), Ester linkage (-CO-O-) POLYMERSCLASSIFICATION OF POLYMERSTHEORY 4 TYPES OF PLASTICS Thermosoftening plasticsThermosetting plastics They are formed by addition polymerization. Eg. Polyethylene, PVC, etc.Theyareformedby condensation polymerization. Eg. Nylon 66, nylon 6, etc. Theyconsistoflinearlong chainpolymerwithlimited cross-links. Theyconsiststhree dimensionalnetwork structure. Theyconsistspolymerof smaller molecular weight. Theyconsistspolymerof higher molecular weight.Theyaresoftenedon heating.Hencetheycanbe reshaped & reused. Theydonotsoftenon heating.Hencetheycannot be reshaped & reused. They can be reclaimed from wastes. They cannot be reclaimed. There inter molecular bonds are weaker. Theyarejoinedbystrong covalent bonds. Theyaresoft,weak&less brittle. Theyarehard,strong& more brittle. Theyaresolubleinsuitable organicsolvents,astheir bonds are weaker. Theyareinsolublein organicsolvent,astheir bonds are stronger.