principle of polymerization

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1、CHAPTER1INTRODUCTIONPolymersaremacromoleculesbuiltupbythelinkingtogetheroflargenumbersofmuchsmallermolecules.Thesmallmoleculesthatcombinewitheachothertoformpolymermole-culesaretermedmonomers,andthereactionsbywhichtheycombinearetermedpolymer-izations.Theremaybehundreds,thousands

2、,tensofthousands,ormoremonomermoleculeslinkedtogetherinapolymermolecule.Whenonespeaksofpolymers,oneisconcernedwithmaterialswhosemolecularwightsmayreachintothehundredsofthousandsormillions.1-1TYPESOFPOLYMERSANDPOLYMERIZATIONSTherehasbeenandstillisconsiderableconfusionconcerningt

3、heclassificationofpolymers.Thisisespeciallythecaseforthebeginningstudentwhomustappreciatethatthereisnosinglegenerallyacceptedclassificationthatisunambiguous.Duringthedevelopmentofpolymerscience,twotypesofclassificationshavecomeintouse.Oneclassificationisbasedonpolymerstructureanddi

4、videspolymersintocondensationandadditionpolymers.Theotherclassificationisbasedonpolymerizationmechanismanddividespolymerizationsintostepandchainpolymerizations.Confusionarisesbecausethetwoclassificationsareoftenusedinterchangeablywithoutcarefulthought.Thetermscondensationandstepa

5、reoftenusedsynonymously,asarethetermsadditionandchain.Althoughthesetermsmayoftenbeusedsynonymouslybecausemostcondensationpolymersareproducedbysteppoly-merizationsandmostadditionpolymersareproducedbychainpolymerizations,thisisnotalwaysthecase.Thecondensation–additionclassificatio

6、nisbasedonthecompositionorstructureofpolymers.Thestep–chainclassificationisbasedonthemechanismsofthepoly-merizationprocesses.PrinciplesofPolymerization,FourthEdition.ByGeorgeOdianISBN0-471-27400-3Copyright#2004JohnWiley&Sons,Inc.12INTRODUCTION1-1aPolymerCompositionandStructurePo

7、lymerswereoriginallyclassifiedbyCarothers[1929]intocondensationandadditionpoly-mersonthebasisofthecompositionaldifferencebetweenthepolymerandthemonomer(s)fromwhichitwassynthesized.Condensationpolymerswerethosepolymersthatwereformedfrompolyfunctionalmonomersbythevariouscondensati

8、onreactionsoforganicchemistrywiththeeliminationofsomes