Lec#3 Polymers I-2

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PolymersPolymersPolymerization, PolymerPolymerization, Polymer

Structure, MorphologyStructure, Morphology

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Objectives

1. Explain the basic steps in polymerization.

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Objectives

1. Explain the basic steps in polymerization.

2. Explain the epoxy/amine reaction mechanism.

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Objectives

1. Explain the basic steps in polymerization.

2. Explain the epoxy/amine reaction mechanism.

3. Identify the grafting/copolymer structures and/or name them.

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Objectives

1. Explain the basic steps in polymerization.

2. Explain the epoxy/amine reaction mechanism.

3. Identify the grafting/copolymer structures and/or name them.

4. Identify or sketch the various isomeric structures possible with a vinyl polymer.

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Objectives

1. Explain the basic steps in polymerization.2. Explain the epoxy/amine reaction mechanism.

3. Sketch/identify the four basic vinyl molecules4. Identify the grafting/copolymer structures and/or

name them.5. Identify or sketch the various isomeric structures

possible with a vinyl polymer.6. Explain the basis for polymer crystallinity.

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Polymer Building BlocksPolymer Building Blocks

H ydrogenH ydrogenCarbon (key)Carbon (key)

OxygenOxygenNitrogenNitrogenFluorineFluorineSiliconSiliconSulfurSulfurChlorineChlorine

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Polymerization ProcessesPolymerization Processes

A ddition PolymerizationA ddition PolymerizationNo ByproductsNo Byproducts

Usually heat drivenUsually heat driven

Condensation PolymerizationCondensation PolymerizationByproducts producedByproducts producedRemoval of byproduct controls rateRemoval of byproduct controls rate

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L inear A dditionL inear A ddition

Begin with ethylene (gas)Begin with ethylene (gas)Monomer or ³mer´ Monomer or ³mer´ Each bond is a sharedEach bond is a sharedelectron pair.electron pair.

A polymer is formed byA polymer is formed bycatalyzing the formation of catalyzing the formation of a free radical:a free radical:

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A ddition Polymerization

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C ondensation ReactionC ondensation Reaction

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Eff ects o f Polymerization SchemeEff ects o f Polymerization Scheme

Polymer may contain residualPolymer may contain residualbyproduct.byproduct.

A ddition polymerization done inA ddition polymerization done insolvent may have residual solventsolvent may have residual solventCleanest polymers are gas phase orCleanest polymers are gas phase oraqueous solution polymersaqueous solution polymers

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Basic Steps in PolymerizationBasic Steps in Polymerization

Initiation:Initiation: Formation of Formation of free radicalfree radical

Propagation:Propagation: Combining of Combining of mers to formmers to formchainschains

Termination:Termination: Elimination of Elimination of free radicalsfree radicals

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Polymerization Step Eff ectsPolymerization Step Eff ects

The actual method of initiation,The actual method of initiation,propagation, termination will affectpropagation, termination will affectfinal properties.final properties.

You cannot easily switch suppliers orYou cannot easily switch suppliers orresin once a particular material andresin once a particular material andfactory have been qualified.factory have been qualified.

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PropertiesProperties

Behavior determined by aBehavior determined by acombination of primary backbonecombination of primary backbonebonds and secondary bonds.bonds and secondary bonds.

Different monomers will haveDifferent monomers will havedifferent secondary bond strengths.different secondary bond strengths.

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L evels o f Polymer ArchitectureL evels o f Polymer Architecture

Monomer TypeMonomer Type

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Families based on an ethenic backbone areFamilies based on an ethenic backbone arevinylvinyl polymers or vinylydinespolymers or vinylydines

PolyethylenePolyethylenePEPE

PolypropylenePolypropylenePPPP

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PolystyrenePolystyrenePSPS

PolyvinylchloridePolyvinylchloridePVCPVC

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L evels o f Polymer ArchitectureL evels o f Polymer Architecture

Monomer TypeMonomer TypeMolecule L engthMolecule L ength

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Molecular Weight:Molecular Weight:

Number AverageNumber Average

Weight AverageWeight Average

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L evels o f Polymer ArchitectureL evels o f Polymer Architecture

Monomer TypeMonomer TypeMolecule L engthMolecule L ength ± ± molecular weightmolecular weight

Mixture of MonomersMixture of Monomers - - copolymerscopolymers

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Types o

f C

opolymersT

ypes of C

opolymersH omopolymerH omopolymer AAAAAAAAAAAAAAAAAAAAAA

RandomRandom CC A CBB A CA BAACCA CBB A CA BAA

A lternatingA lternating A BCA BCA BCA BCA BCA BCA BCA BCBlockBlock AAAA BBBBCCCCAAAA BBBBCCCCGraftGraft

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L evels o f Polymer ArchitectureL evels o f Polymer Architecture

Monomer TypeMonomer TypeMolecule L engthMolecule L ength ± ± molecular weightmolecular weight

Mixture of MonomersMixture of Monomers ± ± copolymerscopolymersMonomer A rrangementMonomer A rrangement - - IsomersIsomers

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Isomerism/Polymer TacticityIsomerism/Polymer Tacticity

IsotacticIsotactic

SindiotacticSindiotactic

RandomRandom

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L evels o f Polymer ArchitectureL evels o f Polymer Architecture

Monomer TypeMonomer TypeMolecule L engthMolecule L ength ± ± molecular weightmolecular weight

Mixture of MonomersMixture of Monomers ± ± copolymerscopolymersMonomer A rrangementMonomer A rrangement ± ± IsomersIsomersBond/Network StructureBond/Network Structure

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Polymer CategoriesThermoplastic ± only secondary bonds between

molecules.-´Plastic´ or reshapable- Melted and formed under pressure

- Higher tooling costs

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Polymer CategoriesThermoplastic ± only secondary bonds between

molecules.-´Plastic´ or reshapable- Melted and formed under pressure

- Higher tooling costs

Thermoset ± primary and secondary bonds betweenmolecule segments.

- Cannot be reshaped- Low viscosity in processing- Cheaper tooling

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Thermoset

Frequent Cross-links Create 3-D Network

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A morphous Polymer ± Lightly Crosslinked

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Semicrystalline Thermoplastic

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L evels o f Polymer ArchitectureL evels o f Polymer Architecture

Monomer TypeMonomer TypeMolecule L engthMolecule L ength ± ± molecular weightmolecular weight

Mixture of MonomersMixture of Monomers ± ± copolymerscopolymersMonomer A rrangementMonomer A rrangement ± ± IsomersIsomersBond/Network StructureBond/Network Structure

Molecular ConformationMolecular Conformation

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A morphousA morphous

Example:Example:

PolycarbonatePolycarbonate

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Crystalline

Example: Polyethylene

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CrystalsCrystals

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L evels o f Polymer ArchitectureL evels o f Polymer Architecture

Monomer TypeMonomer TypeMolecule L engthMolecule L ength ± ± molecular weightmolecular weight

Mixture of MonomersMixture of Monomers ± ± copolymerscopolymersMonomer A rrangementMonomer A rrangement ± ± IsomersIsomersBond/Network StructureBond/Network Structure

Molecular ConformationMolecular ConformationBlends/ A lloysBlends/ A lloys

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L evels o f Polymer ArchitectureL evels o f Polymer Architecture

Monomer TypeMonomer TypeMolecule L engthMolecule L ength ± ± molecular weightmolecular weightMixture of MonomersMixture of Monomers ± ± copolymerscopolymersMonomer A rrangementMonomer A rrangement ± ± IsomersIsomersBond/Network StructureBond/Network StructureMolecular ConformationMolecular ConformationBlends/ A lloysBlends/ A lloysA dditivesA dditives

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Polymer C ategories: NetworkPolymer C ategories: Network

ThermosetThermoset vs vs ThermoplasticThermoplastic

NetworkNetwork vsvs L inearL inear

FixedFixed vsvs ReshapeableReshapeable

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Polymer C ategories: ApplicationPolymer C ategories: ApplicationPlasticsPlasticsA dhesivesA dhesivesFilmsFilmsFibersFibersElastomersElastomers