Module I - Materials Process

8/12/2019 Module I - Materials Process

1/72

RichardE.Eitel

TeachingAssociateProfessor

Email:[email protected]

Office:Burchard307B

DepartmentofChemical

EngineeringandMaterials

Science

StevensInstitute

of

Technology

E344:MaterialsProcessing

IntroductiontoMaterialsScience

andEngineering

2

Introductions

Coursestructure&learning

approachandobjectives.

Thisclassperiodwillservesasanintroductiontothecourse

andMaterials

Science

&

Engineering

discipline.

Exploringstructure

propertyrelationships.

vs


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BorninClevelandOhio:

HOMEoftheBROWNSandtheRockandRollHallofFame!

Undergrad:AlfredUniversity(19941998)

B.S.in

Ceramic

Engineering

SouthernTierofNewYorkState

HomeoftheSaxons

X

Nowhere

Alfred


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PennState:19992006

MaterialsResearchInstitute

MaterialsResearchLaboratoryFoundedin1956:

1stInterdisciplinaryResearchLabinMaterialsScience

Ph.D.inMaterialsScienceand

Engineering:

Thesis:

NovelPiezoelectricCeramics:DevelopmentofHigh,Temperature,HighPerformance

Materials

on

the

BasisofToleranceFactor

UniversityofKentucky(20062013)

Teaching: DepartmentofChemicaland

MaterialsEngineering IntroductiontoMaterials CeramicEngineering MaterialsCharacterization ThreedifferentlabcoursesResearch:

PiezoelectricMaterialsMicrofluidics

MaterialsSynthesis Sensing

Biofluidics

CellBasedSensors


4/72

Pastimes:AsinthingsusedtodobeforeIstartedteaching!

2015NYC

Marathon?

Yearsofeducationalresearchshowsthattheaverageanindividuals

averageattentionspaninapassivelectureisabout15minutes.

Learning howeverrequiresnotjustattentionbutactivethought!

After15minuteofLecture LearninginanActiveClassroom


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TeambasedGuidedInquiry

9

1. Breakinto

groups

of

3or

4.

2. Rearrangeseatsotheyoucantalk

comfortably.

3. Onestudentineachgrouplogonto:

m.socrative.com

4. Room#129851

GuidedInquiryI:Heat(10minutes)

UseFigure1.1.1toanswerthefollowingquestions(workasagroup

makesureeveryoneagreesbeforemovingtothenextquestion):


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ConceptCheckI:

Ahotpieceofcopperisplacedincontactwithacoldbrick?

Ifthecopperloses5caloriesofenergy,howmuchenergy

doesthe

brick

gain?

Guided Inquiry II:

Heat and Work (10 Minutes)

Heat

Transfer of energywhen there is adifference intemperature.

Work Transfer of energywhen there is nodifference intemperature.


7/72

ConceptCheck:

AccordingtotheFirstLawofthermodynamics,couldheatbetransferredfromacoldobjecttoahotobject,resultinginthehotobjectgettinghotterandthecoldobjectgettingcolder'?

14

GuidedInquiryIII:ActiveLearning

(10minutes)


8/72

RichardE.Eitel

AssociateProfessor


Office:Burchard307B



Science

StevensInstitute

of

Technology


01 IntroductiontoMaterialsScience

andEngineering

Bytheendofthislectureyoushouldbeableto:

Theoverallobjectistointroducethefieldofmaterials

science

and

engineering.

Appreciatetheinterdependence

ofstructure,processing,

properties,andperformancefor

materialsdesignandselection.

Classifymaterialonthebasisof

structureandbonding.

Beabletopredictbondingand

materialpropertiesbasedonthe

atomicstructure.


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Thegoalofmaterialsscienceandengineeringistodescribethe

structure,processing,andpropertiesrelationshipwhichdictatethe

performanceofamaterialforaspecificengineeringapplication.

Acompletestructuraldescriptionofanengineeringmaterial

may

span

length

scales

from

the

nano to

the

macro.AtomicStructure:

10 m

BondingandCrystalStructure:

10 10 m

Macrostructure:

10

Microstructure:

10 10 m


10/72

Materialspropertiesarecharacteristicswhichareintrinsic

tothematerialandformthebasisformaterialsselection.

PERFOMANCEREQUIREMENT:

Supporta6000poundtruck TensileStrengthofHardenedSteel:250,000PSI

Materialspropertiesareinputsinordertodesignacomponentto

achievesuitableperformanceinagivenapplication.

HighTensionWire:

PerformanceSpec:90%lighttransmission

MaterialProperty:

TotalHipReplacement:

PerformanceSpec:20yearlife

MaterialProperty:


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Processingincludestheentirehistoryofamaterialrequired

toforminintoacomponentwiththerequiredperformance.

ProcessingimpactBOTHtheSTUCUTREandthePROPERTIES

Theperformanceofamaterialinagivenapplicationisa

consequenceofcarefulmaterialsselectionandengineeringofthe

materialinto

acomponent.


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Materialsclassificationmaydependonwhetherwearetryingto

developunderstandingofselectamaterialsforagivenapplication.

StructuralClassification ApplicationsBasedClassification

Structural

Classification

Ceramics

Polymers

Composites

Metals

Thetraditionalclassificationofmaterialintoceramics,polymers,

metals,andcompositionisprimarilyonthebasisofatomicbonding

andstructure. Ceramics:

Inorganic,nonmetallicsolids

composedofasleastone

metallicandonenon

metallicatom.

Polymers:Macromoleculesformedby

covalentbondingofsimpler

molecularrepeatunits.

Metals:

Pureandalloyedatomic

speciesheldtogetherby

metallicbonding.

Composites:

Twoormoreoftheabovecombined

toproduceanewmaterialwith

uniquepropertiesorcombinations.


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Metals

Consistofpureandalloyedatomsheldtogetherbydelocalizedelectronsthatovercomethemutualrepulsionbetweentheioncores(MetallicBonding)Excellentstructuralmaterials:

high strength, toughness

(resistance to impact)

Electrical,thermalconductors

Atomsarrangedinregularlydefined,

repeatingpositionsthroughoutstructure

Steel:An alloy of iron, containing various amounts of carbon,manganese, and one or more other elements, such as sulfur,

nickel, silicon, phosphorus, chromium, molybdenum, andvanadium. These elements, when combined with iron, formdifferent types of steels with varying properties.

Metals?


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CeramicsandInorganicGlassesInorganic,nonmetallicsolids,composedofacombinationofoneormoremetallic

andoneormorenonmetallicatoms:

Al2O3 (alumina);

SiO2 (quartz, glass)

Mixedatomicbonding(ionicandcovalent)

Highstrength(compression),butbrittle

Excellent(electrical)insulators

Highthermalresistance;resistancetochemicalattack

High-end application: ceramic

tiles for use as heat shield inaerospace vehicles (> 1600C)

Ceramics?


15/72

PolymersMacromoleculesformedbycovalentbondingofsimplermolecularrepeatunits(mers)Easilyprocessedtoawiderangeofshapes,dimensions

Moderatestrength;goodductility. Lightweight.

Usuallynotsuitableforhightemperatureapplications

(>100to200C)

polyethylene

polypropylene polystyrene PVC

Polymers?


16/72

CompositesTwoormorematerialscombinedtoproduceanewmaterialwith

desiredproperties(newpropertiesareaveragedvaluesof

components)

Lowtechexamples:

plywood(panelcomprised

ofmultiplelayersofwood

veneer,plusadhesive;grain

laidat90angles)

concrete(cement[binder]

plussandandgravel)

steelbeltedtires(steel

belts,polyestercord,

rubber)

Hightechexamples:

carbonfiber

epoxy

composites

ceramicfibermetalmatrix

composites(SiC fibersinAl)

Innovation:

Boeings new 787 DREAMLINER is bepredominantly carbon fiber epoxylaminate, yielding a savings of ~20% infuel costs owing to weight reduction.

Alternativelymaterialsmaybeclassifiedandselectedbasedon

theirfunctionorsuitabilitytoaparticularengineeringneed.


17/72

RichardE.Eitel

AssociateProfessor


Office:Burchard307B



Science

StevensInstitute

of

Technology


02 GuidedInquiryAtomicBonding


Theoverallobjectiveofthesesessionistodescribehow

atomic

structure

leads

to

bonding

in

materials.

DefineElectronegativity

Predictthedistributionof

electronsinabond.

Predictthetypesofbonds

formedindifferentatomsand

theirproperties


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Thestructureofmaterialsandtheircorrespondingpropertiesarise

duetotheelectronicstructureoftheconstituentatoms.

Electronicstructure

inmetals

allows

planesofatomsto

slidepasteachother

Electronconfigurationina

hightemperature

superconductor.

In1913Bohrclarifiedthestructureoftheatombytheorizing

electronswereconfinedtospecificallowedstates(orbits).

Explainssimpleemissionspectraofgases.

Allowedenergylevelsina

hydrogenlikeatomarelimitedto

integralvaluesofn:

Where:

h PlanksConstant

massof

an

electron

q fundamentalcharge

permittivityoffreespace

n energylevel(shell)


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Electrontransitionsbetweenallowedstatesareaccompaniedby

theadsorptionoremissionofaquantaorpacketofenergy,for

exampleinthefromofaphoton.

Ionizationenergy(IE)requiredto

removeaboundelectroninthestateyieldingafreeelectron

Allowedenergylevelsinasingle

electronatomwith

effectiveatomic

numberZ:

8

Atomswithmorethanhalffilledoutershellswill

tendtoATTRACTmoreelectronstocreateafull

outershell:Electronegative

Atomswithlessthanhalffilledoutershellswill

tendtogetridofouterelectrons:Electropositive

These

outer

VALANCE

electrons

lead

BONDING.

Emptyandcompletelyfilledshellshavelowerenergythanpartially

filledshells.ThusVALANCEelectronintheoutermostorpartially

filledshell

tend

to

be

particularly

active.


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Therelativetendencyofanelementtogainorlooseelectronsis

quantifiedaccordingtoitselectronegativity .

Atomswith

relatively

high

values

of

:

__________________

Atomswithrelativelylowvaluesof:__________________

Electronegativity=affinityofatomsforelectrons

Atomwithhigherelectronegativityhasastrongerpullonelectrons.

Electrons are closer to atom with higher electronegativity

GuidedInquiryI:Electronegativity

(10

minutes)

m.socrative.comRoom#129851


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A. FeBr

B.BrBr

C. KBr

D.CBr

E. Idontknow

ConceptCheck#1:In which of the following bonds are the electronsmost strongly pulled to one of the atoms?


A. FeBr

B.BrBr

C. KBr

D.CBr

E. Noneof

the

above.

F. Idontknow.

ConceptCheck#2:

In which of the following bonds are the electronsdistributed evenly between the two atoms?


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GuidedInquiryII:TypesofBond

(12minutes)

A.Covalent

B.Ionic

C.Metallic

D.Idontknow

ConceptCheck#3:

What are the primary bonds in the compoundCaF2?



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A.Covalent

B.Ionic

C.Metallic

D.Idontknow

ConceptCheck#4:What are the primary bonds in the compoundGaN?


GuidedInquiryIII:BondCharacter(12minutes)

%IonicCharacter % :

OnlyConsidersIonicand

CovalentBonding

Type of Bond How do you know?

% 100% 1 exp

4

ElectronegativityDifference

:

BondTypeTriangle:

ElectronegativityDifferenceover

AverageElectronegativity


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A. 0%ionic

B. 22%ionic

C. 68%ionic

D. 100%Ionic

E. Idontknow

ConceptCheck#5:What is the ionic character of the bond formed inthe compound FeBr2?


A. Ionic

B. Covalent

C. Metallic

D. Idontknow

ConceptCheck#6:

What is dominant primary bond type in thecompound FeBr2?



25/72

RichardE.Eitel

TeachingAssociateProfessor


Office:Burchard307B



Science

StevensInstitute

of

Technology


03 Crystallography:

lattices,directions&planes

Identifythesevencrystal

systems.

Distinguishbetweenacrystal

system,apointlattice,anda

crystalstructure.

Thegoalofthislectureistodeveloptheskillsrequiredto

describeand

define

the

structure

of

crystalline

solids.

AssignMillerIndicesto

directions[UVW]and

planes(hkl).


vs vs


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Accuratelydescribingtheorderedstructureofcrystalline

materialsrequiresidentifyingseverallayersofstructure.

CrystalStructure

space

filling

polyhedra

PointLattice referencepointsdescribing

symmetricallyequivalentpositions

Basis Atomoratomiccomplex

CrystalStructure

lattice+basis

Therearesevenunique3Dcrystalstructureswhich

encompassall

possible

space

filling

polyhedral.

6Lattice

parameters:

Edges:a,b,c

Angles:, ,ab

NOPOINTSinacrystalstructure!


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The14Bravais pointlatticesincludethelocationsofthe

symmetryequivalentpoints(referencepositions)within

thesevencrystalsystems.

Auguste Bravais

18111863

Latticepoints atoms

Primitivelattices(P)haveexactlyonelatticepointperunit

cell.


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Nonprimitivelatticeshavemultiplepointsperunitcelland

mayincludebodycentered(I),facecentered(F),andend

centered(ABC)types.

PPrimitive F FaceCentered I Body

Sincealllatticepointshaveidenticalsurroundingsthe

choiceof

the

origin

is

arbitrary.


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Toconstructacrystalstructureamotifofbasisunitis

assignedtoeachlatticepoint.

Basis

Lattice Motif (Basis) CrystalStructure+ =

TheSAMEmotifmustbeassignedtoEVERYpointinthe

lattice.

BodyCenteredLatticewith

1AtomPerPoint

SimpleCubicLattice

With2AtomsPerPoint

VS.


30/72

Differentmotifscanproduceverydifferentcrystal

structuresfromthesamelattice.

Positions,directions,andplanesincrystalstructuresare

distinguishedby

maintaining

aspecific

convention

unique

toeach.

Positional

Coordinates:,1,

Direction

Vectors:

Planar

Indices:


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Conventionistodefinearighthandedcoordinatesystemin

whicheachoftheunitcelledgesa,b,andchaveunit

length.

90

90

Specificpositionsaredesignatedusingthecoordinatesh,k,andlwhere

each

value

represents

afraction

of

the

lattice

parametera,b,andc,respectively.

Findthecoordinatesforthe

following:

PointD:

PointC:

PointH:


32/72

DirectionsarespecifiedbylowestintegersvaluesU,V,and

Walongunitvectors,,and andenclosedinsquare

brackets

.

111

Specifiesonlydirection

NOTmagnitude...

Assigningdirectionalindicescanbeperformedbyfollowing

theprocedure:

1. Usingarighthandedcoordinatesystem,determinethe

coordinatesoftwopointsthatlieonthedirection

2. Subtractthepositionofthetailpointfromthecoordinatesof

theheadpoint,toobtainthenumberoflatticeparameters

traveledineachdirection

3. Clearfractionsand/orreducethedifferences,togive(lowest)

integervalues.

4. Writeindicesinsquarebrackets[UVW] (nocommas)

5. Indicatenegativevalueswithoverbar.


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Practice: FindthedirectionindicesforvectorEOatleft:

Findthedirectionalindicesfor

thefollowingvectors(atright):

VectorOA:

VectorOF:

VectorCB:

ImportantNotesaboutDIRECTIONS:

ADIRECTIONanditsnegative

areNOTthesame!

Multiplesofdirections

AREidentical!

(Reducebyconvention) =

Certaingroups

or

familiesofdirections

andtheiroppositesare

equivalent.

Cubic : , , , , , ,


34/72

1

Millerindicesofplanesaredenotedbyintegersh,k,andl

enclosedinparenthesis .

MillerPlanesaredeterminedusing

1. Chooseaplanethatdoesnotpassthroughtheoriginat:0,0,0moveoriginifneeded.

2. Determinefractionalintercepts oftheplanewiththe

crystallographicaxesx,y,andz.

forplanesparalleltoanaxestheinterceptis

3. Takereciprocaloftheintercepts.

4. ClearfractionsbutDONOTREDUCEtolowestintegers.

5. Citeplaneswithparenthesis indicatenegativevalueswithoverbar.


35/72

1

ExamplesandPracticewithPlanes:

ImportantNotesaboutMillerindicesforplanes.

Planesandtheir

NEGATIVES areidentical!

PlanesandtheirMULTIPLES

areparallelbutNOT

identical!

Equivalentfamiliesofplanes

areindicated

by

Braces

{hkl}:

Family : , , , , ,


36/72

RichardE.Eitel

AssociateProfessor


Office:Burchard307B



Science

StevensInstitute

of

Technology


04 CrystallineSolids

2

Thegoalofthislectureistodeveloptheskillstodescribe

andpredict

both

structure

and

properties

of

crystalline

materials.Bytheendofthislectureyoushouldbeableto:

Describethecrystalstructuresof

severalcommonengineeringmetals

andceramics

Estimatedensitiesofbothmetal

andceramicmaterialsusingonly

theirknowncrystalstructure.

Useatomicradiitopredictthe

structureofsimpleionic

compounds.


37/72

1.Yes

2.No

3.Imnotsure

ConceptCheck:CanyouIdentifyCommonUnitCellsand

Calculatetheirassociatedproperties(latticeparameter,

mass,volume, density,etc)?

GuidedInquiryI:CrystalsandGlasses

(5

minutes)

Hypotheticalarrangementofatomsinacrystalandaglass.


38/72

1.Itwouldbedifferent.

2.Itwouldbethesame.

3.Idontknow.

ConceptCheck:Aglassrodhasastiffnessof70GPa when

pulledalongitslength.Howwouldyouexpectthestiffness

tochangeifyoupulleditperpendiculartoitslength?

Crystalstructuresareusedtodescribethelongrange

periodicitypresent

in

crystalline

materials.

LongRangeOrder: ShortRangeOrder:


39/72

Crystallinematerialsrepresentthestablelowestenergy

stateofanysolid.

Dense,regular

packing

Typicalbondlength

Typicalbondenergy

Nondense,

random packing

Typicalbondlength

Typicalbondenergy

GuidedInquiryII:CrystalUnitCells

(10

minutes)

SimpleCubic

(SC)

BodyCentered

Cubic

(BCC)

FaceCentered

Cubic

(FCC)


40/72

1. 1

2. 2

3. 3

4. 6

5. Idontknow.

ConceptCheck:Forthecrystalstructureshown,

howmanyblueatomsarethereperunitcell(i.e.,

withinthe

unit

cell)?

1. 1

2. 2

3. 4

4. 8

5. Idontknow.

ConceptCheck:Forthecrystalstructureshown,

howmany

green

atoms

are

there

per

unit

cell

(i.e.,

withintheunitcell)?


41/72

TheUNITCELListhesmallestessentialunitofacrystalline

material.

UnitCell

of

Cesium

Chloride

Keycharacteristics ofaunitcell:

Dimensionsspecifiedbysixlattice

parameters, ,, ,,

Basedononeofthe14Bravais

lattices

Includesexactlyonebasisateach

latticepoint

Repeatsindefinitelyinall

direction Canbeusedtocalculatethe

densityofthecrystallinephase

Mostmetaltypicallyassumeoneofthreebasiccrystal

structures.MetalswiththeBodyCentered

Cubic(BCC)structureinclude:

Tungsten,chromium,iron,

molybdenum,vanadium

MetalswiththeFaceCentered

Cubic(FCC)structureinclude:

aluminum,calcium,copper,gold,

lead,nickel,platinum,silver

MetalswiththeHexagonalClose

Packed(HCP)structureinclude:

Cadmium,Titanium,Zinc,

Magnesium,Cobalt

BCC

FCC

HCP


42/72

GuidedInquiryIII:AtomicPackingFactor

(10minutes)

= lattice

parameter

R = atomicradius

SC BCC FCC

AtomicPacking

Factor(APF):

A. 0.52

B. 0.68

C. 0.74

D. 1.00

E. Idontknow

ConceptCheck:Whatistheatomicpackingfactor

(APF)for

aSC

unit

cell?


43/72

GuidedInquiryIV:Density

(10minutes)

SC BCC FCC

A.

B.

C.

D. /

E. Idontknow

Concept Check: What is the

relationship between a and R for anFCC unit cell?

FCC


44/72

Ceramiccrystalstructuresarebasedoneitherionicor

covalentbondingoftheconstituentspecies.

ConsiderCovalent

bonding:Consider

an

ionically bonded

ceramic

GuidedInquiryV:InterstitialSites

(10minutes)


45/72

1

A. Originalatoms

B. Interstitialatom

C. Idont

know

Concept Check: Basedontherelativesizesofanionsandcations,ifthiswereanioniccompound,

whichatoms

would

be

the

anions;

the

original

atomsatthecornersoftheunitcell,orthe

interstitialatomyouadded?

Consideringtheclosestpackingofatomsonly74%ofthe

spaceis

occupied,

these

holes

or

interstices

offer

sites

for

additionalatoms...impurities,dopants,compounds...


46/72

1

Inionically bondedceramicsstablecrystalstructuresmust

balancetheelectrostaticinteractionsofoppositelycharged

ions.

+

+

+

Cations willsurroundthemselveswiththe

maximumnumberofoppositelycharged

anionspossible!

Radiusratioscanbeusedtopredictthenumberofnearest

neighbors(Coordination

number)

of

various

sized

cations.


47/72

1

GuidedInquiryVI:DensityofCeramics

(10minutes)

A.

B.

C.

D. +

E. Idontknow

Concept Check: What is the general

formula for the lattice parameter of athe rock salt structure?


48/72

RichardE.Eitel

AssociateProfessor


Office:Burchard307B



Science

StevensInstitute

of

Technology


05 StructureandProperties

ofPolymers

2

Thegoalofthisdiscussionistobeabletodescribethe

macromolecularstructure

of

polymers

and

relate

this

to

theirengineeringproperties..Bytheendofthisdiscussionyoushouldbeableto:

Describetheroleofpolymerchain

lengthonkeyengineering

properties.

Classifythebasicstructuresof

polymerchains.

Predicttrendsinthecrystallinity

andpropertiesofpolymerbasedon

theirmolecularweightandchain

structure.


49/72

Polymersaregiantmacromoleculesconsistingof10sto

many1,000sofcovalentlybondedrepeat(mer)units.

mer

GuidedInquiryI:AverageMolecularWeight

(10

minutes)



50/72

A. 0.0012

B. 831.75

C. 832

D. 1,472,800

E. I don't know.

ConceptCheck:What is the DP for polypropylene with amolecular weight of 35,000 g/mol?


A. B. g/C. D. It is unit less

E. I don't know.

ConceptCheck:

What are the units for DP?



51/72

Thechainlengthofpolymersischaracterizedbythedegree

ofpolymerization(DP)andthemolecularweight.

PolymersareALWAYSmixtureofmacromoleculesof

varyingmolecularweights

NumberAverageMolecularWeight

:

Where:

isthemedianmolecularweightofachainintheithsizerange.

isnumberfractionofchainsintheithsizerange isweightfractionofchainsintheithsizerangeismolecularmassoftherepeat(mer)unit

=

WeightAverageMolecularWeight:

Degreeofpolymerization(DP):

Polydispersity Index(PDI):

0

0.05

0.1

0.15

0.2

0.25

FractionalContent

MolecularWeightRange(g/mol)

FractionalDistrubtionofMolecularWeights

WeightFraction(wi)

NumberFraction(ni)

GuidedInquiryII:MolecularWeightCalculations

(8

minutes)Considerasampleofplasticwhichyouknowis15mol%polymer

moleculeswithmolecularweight500,000g/mol,and85mol%

polymermoleculeswithmolecularweight150,000g/mol.

NumberAverageMolecularWeight:

WeightAverageMolecularWeight:

Degreeofpolymerization (DP):

Polydispersity Index(PDI):


52/72

A. 119,600g/mol

B. 202,500g/mol

C. 280,000g/mol

D. Idontknow

ConceptCheck:What is the number average molecular weight forthe above mixture?


A. 119,600g/mol

B. 202,500g/mol

C. 280,000g/mol

D. Idontknow

ConceptCheck:

What is the weight average molecular weight forthe above mixture?



53/72

A.Yes

B.No

C.isalwayslessthan.D.Idontknow

ConceptCheck#3:Can belessthan?Why?


Formanysimplelinearpolymers,materialpropertiesare

dictatedby

chain

length

and

weak

secondary

bonding

betweenchains.


54/72

GuidedInquiryIII:MWandProperties.

(5minutes)

Considertwodifferentplatesofspaghetti.Oneinwhichallthe

strandsarethefulllengthandoneinwhichthestrandhavebeencutintoshortsegments.

A. 100,000 g/mol

B. 200,000 g/mol

C. Theyhavethesamestrength.

D. Idontknow

ConceptCheck#4:

Which has a higher strength; polyethylene of100,000 g/mol or 200,000 g/mol?



55/72

ConceptCheck#5:Which flows more easily; polyethylene of 100,000g/mol or 200,000 g/mol?


A. 100,000 g/mol

B. 200,000 g/mol

C. Theyflowequally.

D. Idontknow

Polymersmayalsobecharacterizedbychainlengthand

meanend

to

end

Distance.

Total(stretchedout)chainlength(L):

2Meanendtoenddistance(r):

Where:

d bondlength

N numberofbondsinchain

anglebetweenadjacentatoms

=109.5o forCC

L


56/72

Thepropertiesoflinearpolymerscanbemodifiedby

introducingbranchingorcrosslinking.

Linear

secondary

bonding

Branched

Cross-Linked Network

Likemetalsandceramicspolymersmayexhibithighly

orderedcrystalline

regions.


57/72

1

GuidedInquiryIV:PolymerCrystallinity.

(10minutes)

a) Polyethyleneorpolystyrene.

b) Polyethylenewithmanylongbranchesorpolyethylene

withafewshortbranches.

c) Atactic polypropyleneorisotacticpolypropylene.

d) Polypropyleneorpoly(ethyleneterephthalate)(PET).

e) Polyethyleneorarandomcopolymerof50%ethylene

repeatunitsand50%propylenerepeatunits.

f) PETmeltedandrapidlycooledtoroomtemperatureor

PETmelted,cooledto150 C,heldtherefor1hour,and

thencooledtoroomtemperature.

Reportout:

Which of the following pairs is more crystalline?



58/72

1

Theproductionofmostpolymermacromoleculesfrom

theirmonomeroccursbyoneoftwopolymerization

routes.

Addition(Chaingrowth)

polymerization:

Condensation(stepreaction)

Polymerization

(byproductproducedoftenwater)

Initiatormonomer

Polyethylene:

Polyethyleneterephalate

Thermoplasticpolymersaretypicallylinearorslightly

branchedand

soften

on

heating

allowing

them

to

be

easily

(re)formedandreadilyrecycled.


59/72

1

Thermosetpolymersreactonmixingorunderactionof

heatformingextensivecrosslinks.

Example: Bakelitefirstcompletely

syntheticplastic,

1907.


60/72

RichardE.Eitel

AssociateProfessor


Office:Burchard307B



Science

StevensInstitute

of

Technology


06 MaterialsCharacterization

Methods

Theoverallobjectivethislectureistogiveyoutheskillstoapply

severalofthemostwidelyusedmaterialscharacterization

methods:


Calculateinterplanar spacings inmaterialspossessingacubiccrystalstructure.

UseBraggsLawtorelateexperimentaldiffractiondatatointerplanar spacing.

CalculatemeangraindiameterandATSMgrainsizefrommicrostructureimages.


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Diffractionistheapparentbendingofwavesaround smallobjects

andthespreadingoutofwavebeyondsmallopenings.

Beyondan

Opening Around

A

Corner

Theapparentspreadingduetodiffractiondependsonthe

wavelength

of

the

wave

or

particle.

SpreadingofWhiteLightSource DispersionofSoundWaves?


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Youngsdoubleslitexperimentrevealedunexpected

propertiesoflightandquicklymovingparticles.

https://www.youtube.com/watch?feature=player_detailpage&v=Iuv6hY6zsd0

Theperiodicityofinterferencepatternsproducedby

diffraction

experiments

are

related

to

the

geometry

of

the

slitorstructurecreatingthepattern.


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GuidedInquiryI:BraggsLaw

(10minutes)

Ifconstructiveinterferenceoccursfromtwoplanesofatomsforascatteringangle(theta)of20.0degreeswhatisthedistance(d)betweentheplanes,ifthethewavelengthofthewavesis0.154nm?

A. 0.450nm

B. 0.225nm

C. 0.119nm

D. 0.0843nm

E. Idontknow

ConceptCheck:


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Theconditionforconstructiveinterferencefromequally

spacedlayersisgivenbyBraggsNoblePrizeWinningLaw.

ConstructiveInterferencefor

ABC=n*lambda

1912@21YearsOld!

d

WhataretheconditionsforwhichdiffractionOccurs?

2

Considern=1

2


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Whataretypicalspacings (dspacings)betweenatomic

planes?SimpleRelationshipsexistdepending

onthe

crystal

system

of

the

crystal

structure:

General(othorhomic)

+

Cubic(a=b=c):

Tetragonal

:

GuidedInquiryII:Interplanar Spacings

(10

minutes)


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Diffractionexperimentscanbeusedtodescribethestructureand

atomicpositionsinbothsingleandpolycrystalmaterials.

PowderDiffraction

with

Area

DetectorSingleCrystalDiffraction

Powderdiffractionisusedtocollectdataonthefullsetof

interplanar spacing

by

equally

sampling

all

orientations.

PhotographicMethod DigitalMethod


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GuidedInquiryIII:DiffractionExperiments

(10minutes)

Dependingonthecrystalstructurenotallsetofplanes

produce

diffraction

events.


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Microscopyisusetorecordgeometricalstructureand

orientationofmaterialsatthemicroscopicscale(


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1

Opticalmicroscopesusevisuallighttocreateimagesand

characterizetheopticalpropertiesofmaterials.

PracticalResolution

Limit:

~1micron

IdentificationofMineralsbyOpticalProperties:

BoneCancer

Cell

Image:Nikon2012SmallWorld

Intransmissionelectronmicroscopyhighenergyelectrons

are

use

to

achieve

atomic

scale

images

of

thin

(~10nm)

sectionsofmaterial.

ResolutioninaTEM:

HighEnergyElectrons:

1

@300KeV~ 2.0 pm

Schematic

PracticalResolutionlimit:

0.08nm~1


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1

TEMscanbelargebutarealwaysEXPENSIVE!

HVEMJEOL1.25MeV

FEITitan300KeV

>$3MILLION

USD??

Scanningelectronmicroscopeelectronicallyacquireanimageby

scanning(rastering)afocusedbeamofelectronsacrossasample

surface.

Resolutionlimit:

ProbeSize

Interactionvolume

~1nm


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1

Scanningelectronmicroscopesarehavebecometheworkhorse

microscopeofchoiceforroutinematerialscharacterization

MinimalSample

Prep

CompatiblewithSizeofFeatures

ReasonableCost:

$100K500K

Thechoiceofmicroscopicmethodsdependsonthescale

and

type

of

information

the

is

needed!

ThefollowingareimagesofCarbonnanotubes:

OpticalMicroscope(Fluorescence):30Mnanotubefilamentusedforsolarenergyharvesting

ScanningElectronMicroscope:Bundlesofnanotubes.

TransmissionElectronMicroscope:atomicspacinginasinglemultiwallnanotube


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MicrostructureAnalysis

Module I - Materials Process

Documents

Module I - Materials Process