POLYMERIC MATERIALS: introduction to polymer

polymer introduction

1. CHAPTER 1
POLYMERIC MATERIAL

2. INTRODUCTION
Describe general concept of
polymer.
01
PLASTIC CLASSIFICATION
Identify plastics classification.
02
CALCULATION
Calculate the degree of
polymerization, molecular
weight and mole fraction of
copolymer.
05
STRUCTURE OF POLYMER
State the structure of polymer.
03
POLYMERIZATION REACTION
Discuss the various
polymerizationreaction and
step.
04
TABLE OF CONTENTS

3. INTRODUCTION01

4. •AMONOMERisthesingleunitorthemoleculewhichisrepeatedinthepolymerchain.
•Itisthebasicunitwhichmakesupthepolymer.
•Therepeatsubunitinthepolymerchainiscalledamer
INTRODUCTION
TERMS DEFINATION : MONOMER

5. •ThewordPOLYMERcomesfromtheGreekwords
•“poly”=“many”,and“meros”meaning“parts”or“repeatingunits”
•Polymersaremacromoleculesformedbyrepeatedlinkageoflargenumberofsmall
moleculescalledmonomers
•Mostpolymersarebasedoncarbonandarethereforeconsideredorganicchemicals
INTRODUCTION
TERMS DEFINATION : POLYMER

6. •POLYMERIZATIONisthechemicalprocessinwhichlargenumbersofmonomerscombine
togetherbycovalentbondstoformapolymerwithorwithouttheeliminationofsimple
moleculeslikewater,HCl,etc.
INTRODUCTION
TERMS DEFINATION : POLYMERIZATION

7. •PLASTICwordisderivedfromtwoGreekwords'plastikos'and'plastos'whichmeans'fit
formoulding'and'moulded’.
•Plasticsingeneralarereferredaspolymersbecausetheyaremadeupofpolymers.
•Plasticiswidelyusedindifferentformslikebottles,bags,boxes,fibers,filmsetc.
•Thetermplasticsisdefinedasamixture(ofapolymerwithadditives)thatcanbe
transformedbyflowingormouldinginliquidormoltenstate.
INTRODUCTION
TERMS DEFINATION : PLASTICS

8. INTRODUCTION
USAGES
USES OF
POLYMERS
Packaging
Medical
Recreational
TextilesHousewares
Transportation
Entertainment

9. PLASTIC
CLASSIFICATION
02

10. PLASTIC CLASSIFICATION
CLASSES OF POLYMER
CLASSES OF POLYMER
THERMOPLASTIC THERMOSET ELASTOMER

11. •THERMOPLASTIC:apolymerthatcanbemeltedandmouldedintoashapethatisretained
whenitiscooled
•EXAMPLE:Polyethylene,polyvinylchloride,polypropylene,polystyrene,andnylon
•THERMOSET:apolymerthatcanbemouldedwhenitisfirstpreparedbut,onceitis
cooled,(sometimecalled“curing”)hardensirreversiblyandcannotbere-melted
•EXAMPLE:Phenolics,epoxies,andcertainpolyesters
PLASTIC CLASSIFICATION
CLASSES OF POLYMER

12. •ELASTOMERS:Thesearerubber–likesolidswithelasticproperties.
•Intheseelastomericpolymers,thepolymerchainsareheldtogetherbytheweakest
intermolecularforces.
•Theseweakbindingforcespermitthepolymertobestretched.
•Afew‘crosslinks’areintroducedinbetweenthechains,whichhelpthepolymerto
retracttoitsoriginalpositionaftertheforceisreleasedasinvulcanisedrubber
•EXAMPLE:Naturalrubber(vulcanized)Syntheticrubbers
PLASTIC CLASSIFICATION
CLASSES OF POLYMER

13. STRUCTURE OF
POLYMER 03

14. •AMORPHOUS=Thepolymerchainsarein
randomarrangement
•TheCRYSTALLINEregion(crystallite)has
anorderlyarrangementofmolecules.The
higherthecrystallinity,theharder,stiffer,
andlessflexiblepolymer
•Polymersaresemi-crystallinematerials.
•Itmeanstheyhavebothamorphousand
crystallineregions.
STRUCTURE OF POLYMER
AMORPHOUS & CRYSTALLINE

15. •Infact,polymershaveregionsof
crystallinity,calledcrystallites,embedded
inamorphousregions.
•Crystallitesprovidestrengthandhardness
andtheamorphousregionsprovide
flexibilitytothepolymericmaterial.
•Density(crystallinepolymer)>density
(amorphouspolymer)
STRUCTURE OF POLYMER
AMORPHOUS & CRYSTALLINE

16. •Polymerscanbehomopolymerorcopolymerwhenthenumberofmonomersareoneand
tworespectively.
STRUCTURE OF POLYMER
HOMOPOLYMER & COPOLYMERS
•HOMOPOLYMER :ifthepolymers
consistofmonomerofidentical
chemicalstructurethentheyare
calledhomopolymers

17. •COPOLYMERS:MoleculeswhicharebuiltupofatleastTWOdifferentkindsofmonomer
areknownasco-polymers.
•Thus,aco-polymerisobtainedwhenTWOORMOREsuitablemonomersarepolymerised
together.
•Thechainsofco-polymerconsistofrepeatingunitsderivedfromeachmonomer.
STRUCTURE OF POLYMER
TYPES OF COPOLYMERS

18. •Followingaresomecommontypesofco-polymers:
STRUCTURE OF POLYMER
TYPES OF COPOLYMERS
Alternating
co-polymers
Block
co-polymers
Random
co-polymers
Graft
co-polymers

19. •Thedifferentrepeatingunitsalternateineachchain.
•IfAandBrepresenttwodifferentunitsthenanalternatingco-polymerwillbe
representedas:
-ABABABAB-
STRUCTURE OF POLYMER
ALTERNATING CO-POLYMERS

20. •Insuchcopolymers,blockofrepeatingunitsofonetypealternatewithblockofanother
type,e.g.SBS(styrene-butadiene-styrene)
-AAAABBBBAAAABBBB-
STRUCTURE OF POLYMER
BLOCK CO-POLYMERS

21. •Inthistypeofcopolymers,thedifferentrepeatingunitsarenotarrangedinasystematic
mannerbutarerandomlyarranged,
-ABAABABBAAABA-
•Eg;commercialcopolymersofbutadieneandacrylonitrile
STRUCTURE OF POLYMER
RANDOM CO-POLYMERS

22. •Insuchco-polymers,blocksofone
repeatingunitsareattachedorgraftedto
ablockoflinearpolymer,e.g.Highimpact
polystyrene
STRUCTURE OF POLYMER
GRAFT CO-POLYMERS

23. STRUCTURE OF POLYMER
TACTICITY (STEREOISOMERISM)
•Theorientationofmonomericunitsorfunctionalgroupsinapolymer
moleculecantakeplaceinanorderlyordisorderlymannerwith
respecttothemainchainisknownastacticity
•Thedifferenceinconfiguration(tacticity)doaffecttheirphysical
properties.

24. •Ifthegroupsattachedtothecarbonarearrangedonthesamesideofthemainchain,the
polymeriscalledIsotacticpolymer.
•Thebestexampleispolypropylene.
•Isotacticpolypropylenehasexcellentmechanicalproperties
STRUCTURE OF POLYMER
ISOTACTIC POLYMER

25. •Ifthegroupsattachedtopthecarbonchainarearrangedrandomly,thepolymeriscalled
Atacticpolymer.
STRUCTURE OF POLYMER
ATACTIC POLYMER
Can’t Crystallize

26. •Ifthegroupsattachedtothecarbonchainarearrangedinanalternatingsideofthemain
chain,thepolymeriscalledSyndiotacticpolymer.
STRUCTURE OF POLYMER
SYNDIOTACTIC POLYMER

27. POLYMERIZATION
REACTION
04

28. •Polymerizationistheprocessbywhichsimple(monomer)moleculesjointogethertoform
verylarge(polymer)molecules.
•Hence,thesynthesisoflargemolecularweightpolymersbythecombinationofmonomer
moleculesistermedaspolymerization.
POLYMERIZATION REACTION
INTRODUCTION

29. POLYMERIZATION REACTION
POLYMERIZATION METHOD
BY OPENING A DOUBLE BOND
01
02
03
BY OPENING A RING
BY USING MOLECULES HAVING TWO
FUNCTIONAL GROUPS
•Therearethreedifferentwaysfordoingpolymerization:

30. POLYMERIZATION REACTION
TYPES OF POLYMERIZATION
TYPESOF POLYMERIZATION
ADDITION POLYMERIZATION CONDENSATION POLYMERIZATION

31. •Theadditionreactioninwhichmonomerswithdoublebondsarejoinedtogetherby
covalentbondstoformalargemolecule(polymer)withoutthelostofasmallmolecule.
•Theproductisanexactmultipleoftheoriginalmonomericmolecules.
•Monomerformakingadditionpolymermaybealkeneoralkenederivatives(
chloroethene)
•Informationofadditionpolymers,thecarbon-carbondoublebondineachmonomeris
brokenopenandreplacedbyacarbon-carbonsinglebond.
•Thisenableseachofthetwocarbonatomtoformanewsinglebondwithothermolecule
toformachain.
POLYMERIZATION REACTION
ADDITION POLYMERIZATION

32. •Additionpolymerizationreactionsproceedbyachainreactionconsistingofthree
importantsteps:
(i)Initiationortheformationofanactivecentre,
(ii)Propagationortheformationofapolymerhavingtheactivecentre
(iii)Terminationorremovaloftheactivecentre.
POLYMERIZATION REACTION
ADDITION POLYMERIZATION

33. •Modelofaddition(chain)polymerization:
(1)initiation,
(2)rapidadditionofmonomers
(3)resultinglongchainpolymermoleculewithnmersatterminationofreaction
POLYMERIZATION REACTION
ADDITION POLYMERIZATION

34. •Thetwodifferenttypesofactivecentreshavebeenfoundtobeformedduringthe
additionpolymerization,
A)Free radical mechanism
B) Ionic mechanism.
•Free-radical polymerization form only LINEAR molecules.
•A FREE RADICAL can be defined as an atom, often part of a larger group, that has an
unpaired electron (free electron) that can covalently bond to an unpaired electron (free
electron) of another atom or molecule.
ADDITION POLYMERIZATION
INITIATION -ACTIVE CENTRE
STEP 1

35. •Itinvolvestheformationofafree-radicalfromaradicalinitiatorsuchasbenzoyl
peroxides,Hydrogenperoxide,H2O2organicperoxideandothermaterialsthatcan
generatefreeradicals.
•Thisinitiatorfreeradicalisproducedbymanywaybutoneoftheimportantwayis
decompositionofthecompoundbysunlight,heat,catalystetc.
•Hydrogen peroxide, H2O2can decompose into two free radicals, as shown by the
following equations. Using electron-dot notation for the covalent bonds,
ADDITION POLYMERIZATION
INITIATION STEP
STEP 1

36. •Usingstraight-linenotationforthecovalentbonds,
•Anorganicperoxidecandecomposeinthesamewayashydrogenperoxide.
•IfR-O-O-Rrepresentsanorganicperoxide,whereRisachemicalgroup,thenupon
heating,thisperoxidecandecomposeintotwofreeradicalsinamannersimilartothat
ofhydrogenperoxide,as
ADDITION POLYMERIZATION
INITIATION STEP
STEP 1

37. ADDITION POLYMERIZATION
INITIATION STEP
STEP 1

38. •Theradicalsoformedthenaddstothemonomertoformanewfreeradical,e.g.,itaddsto
vinylmonomerinthefollowingway
ADDITION POLYMERIZATION
CHAIN INITIATION
STEP 2

39. •CHAININITIATION(EXAMPLEPVC)
ADDITION POLYMERIZATION
CHAIN INITIATION
STEP 2

40. •CHAININITIATION(EXAMPLEPE)
ADDITION POLYMERIZATION
CHAIN INITIATION
STEP 2

41. •Thenewfreeradicalnowaddstoanothermoleculeofmonomertoformanothernew
freeradicaluntilalargefreeradicalisformed.
ADDITION POLYMERIZATION
PROPAGATION STEP
STEP 3

42. •PROPAGATIONSTEP(EXAMPLEPVC)
ADDITION POLYMERIZATION
PROPAGATION STEP
STEP 3

43. •PROPAGATIONSTEP(EXAMPLEPE)
•Thepolymerchainsinchainpolymerizationkeepgrowingspontaneouslybecausethe
energyofthechemicalsystemisloweredbythechainpolymerizationprocess.
ADDITION POLYMERIZATION
PROPAGATION STEP
STEP 3

44. •Terminationofchainsusuallyoccursbyradicalcouplingordisproportionationreactions.
•Bycouplingorcombination
ADDITION POLYMERIZATION
TERMINATION STEP
STEP 4

45. •Disproportionation:Inwhichahydrogenatomofoneradicalcentreistransferredto
anotherradicalcentre.
•Thisresultsintheformationoftwopolymermolecules,onesaturatedandother
unsaturated,e.g.,
ADDITION POLYMERIZATION
TERMINATION STEP
STEP 4

46. ADDITION POLYMERIZATION
SUMMARY
STEP 1Free radical generation
STEP 2Chain initiation step
STEP 3Chain propagation step
STEP 4Termination step
Rrepresents the active initiator, and
.is an unpaired electron.
Termination using coupling orcombination method
Represent with Rin the coming step

47. •Thecondensationpolymersareformedbyrepeatedcondensationreactionbetweentwo
differentbi-functionalortri-functionalmonomericunits.
•Inthesepolymerizationreactions,theeliminationofsmallmoleculessuchaswater,
alcohol,hydrogenchloride,etc.takeplace.
•Theexamplesareterylene(dacron),nylon6,6,nylon6,polyester(PET),etc.
CONDENSATION POLYMERIZATION

48. COMPARISION
ADDITION VS CONDENSATION POLYMERIZATION
AdditionPolymerization CondensationPolymerization
Polymer growth
mechanism
Chain reaction Step by step reactions
Initiator needed Yes No
Type of monomer Contains carbon-carbon double
bond
Has reacting bifunctional
groups on the ends
By product form No Yes
Polymer chain
characteristics
A few, long chains Many not very long chains
Branching Possible Unlikely

49. CALCULATION
05

50. •Sincemoleculesinagivenbatchofpolymerizedmaterialvaryinlength,nforthebatchis
anaverage;itsstatisticaldistributionisnormal.
•Themeanvalueofniscalledthedegreeofpolymerization(DP)forthebatch.
•ByknowingthevalueofDP,themolecularweightofthepolymercanbecalculated.
•Itisrepresentedbythefollowingrelationship,
Mn= (DP) M0
Mnisthenumbermolecularweightofthepolymer,
DPisthedegreeofpolymerization,
M0isthemolecularweightoftheREPEATINGUNIT/monomer.
•DPaffectspropertiesofthepolymer:higherDPincreasesmechanicalstrengthbutalso
increasesviscosityinthefluidstate,whichmakesprocessingmoredifficult
DEGREE OF POLYMERIZATION
INTRODUCTION

51. CalculatethemolecularweightofthepolythenepolymergivenDPis100.
(CH2–CH2)nPolythenehere‘n’istheDP.
Molecularweightofthepolythene=DPXMolecularweightofpolythene
=100X28
=2800
DEGREE OF POLYMERIZATION
EXAMPLE

52. •TheNUMBERAverageMolecularWeight(Mn)canbedeterminedby,
Mn =ΣxiMi
Mnisthenumbermolecularweightofthepolymer,
xiisthefractionofthetotalnumberofchainswithineachrange,
Miisthemeanmolecularweightofeachsizerangeofpolymerchains.
•TheWEIGHTAverageMolecularWeight(Mm)canbedeterminedby,
fiistheweightfractionofthepolymerchains,
Miisagainthemeanmolecularweightofeachrange.
AVERAGE MOLECULAR WEIGHT
INTRODUCTION

53. •CalculatetheweightaveragemolecularweightMmforathermoplasticthathasthe
followingweightfractionsfiforthemolecularweightrangeslisted:
AVERAGE MOLECULAR WEIGHT
EXAMPLE

54. AVERAGE MOLECULAR WEIGHT
EXAMPLE

55. Acopolymerconsistsof70wt%polystyreneand30wt%polyacrylonitrile.Calculatethe
molefractionofeachcomponentinthismaterial.
Molesofpolystyrene
MWpolystyrene=9Hatoms×1g/mol+8Catoms×12g/mol
=105g/mol
No.ofmolesofpolystyrenein100gofcopolymer=70g/105g/mol
=0.667mol
MWPAN=3Hatoms×1g/mol+3Catoms×12g/mol+1Natom×14g/mol
=53g/mol
No.ofmolesofpolyacrylonitrilein100gofcopolymer=30g/53g/mol
=0.566mol
MOLE FRACTION OF COPOLYMER
EXAMPLE

56. •Thus, the mole fractions of the components are calculated as:
MOLE FRACTION OF COPOLYMER
EXAMPLE

57. •AnABScopolymerconsistsof25wt%polyacrylonitrile,30wt%polybutadieneand45wt
%polystyrene.Calculatethemolefractionofeachcomponentinthismaterial.
•
MOLE FRACTION OF COPOLYMER
EXAMPLE 2

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NUZUL ARDZAN MOKHTAR
POLITEKNIK KUCHING SARAWAK
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