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Give the preparation of (i) Polyacrylonitrile (ii) Teflon (iii) Nylon 6,6 (iv) Nylon-6. |
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Answer» Solution :(i) Polyacrylonitrile: Acrylinitrile (monomer) on polymerisation in the presence of a peroxide catalyst gives polyacrylonitrile or orlon. `underset("acrylonitrile")(nCH_(2)=CH-)CNoverset("polymerisation")(to) -underset("repeating unit") (CH_(2))-overset(CN)overset(|)(CH)-to underset("polyacrylonitrile" ("Orplon"))(CH_(2)-overset(CN)overset(|)(CH)_(n))` It is used in making clothes, caprets and blankets. (ii) Teflon (July '16): Tetrafluoroethylene (monomer) on polymerisation in the presence of oxygen as a catalyst under high pressure forms Teflon. `underset("tetrafluoroethylene")(nCF_(2)=F_(2))overset("polymerlsation")(to)underset("repeating unit")(-CF_(2)-CF_(2))- to underset("teflon")((CF_(2)-CF_(2))_(n))` It is used in coating of cooking pans, gaskets, valves,seats, etc. (iii) Nylon 6,6: Nylon 6,6 is a linear polyamide polymer FORMED by the condensation polymerisation reaction. The monomers used in the preparation of Nylon-6,6 are: 1. Adipic acid: `HOOC-(CH_(2))_(4)-COOH` 2. Hexamiethylene diamine, `H_(2)N-(CH_(2))_(6)-NH_(2)` When equimolar aqueous solutions of adipic acid and hemaxethylene diamine are mixed and heated, there is neutralization to form a nylon salt. During polymerisation at 553 K nylon salt loses a water molecule to form nylone 6,6 polymer. `underset("Hemaxethylenediamine")(H_(2)N-(CH_(2))_(6)-NH_(2))+HOOC-underset("Adipic acid")((CH_(2))_(4))-COOHunderset(H_(2)O)overset(Delta)(to)` `underset(("hexamethylene diamonium adiapate")) underset("Nylon salt")([H_(3)N-(CH_(2))_(6)-NH_(3)OOC(CH_(2))_(4)COO])` `n[H_(3)N-(CH_(2))_(6)underset("Nylon salt")(-NH_(3))OOC(CH_(2))_(4)COO] underset(553K)overset(-2nH_(2)O)(to)` `underset("Nylon6,6")(HN-(CH_(2))_(6))-NH-overset(O)overset(||)(C)-(CH_(2))_(4)-overset(O)overset(||)(C)_(n)` |
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