11 Polymer Composite Processing

8/13/2019 11 Polymer Composite Processing

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POLYMERMATRIXCOMPOSITES

StartingMaterialsforPMCs

OpenMoldProcesses

ClosedMold

Processes

FilamentWinding

Pultrusion Processes

OtherPMC

Shaping

Processes


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verv ewo

Apolymermatrixcomposite(PMC)isacompositematerial

consisting

of

a

polymer

imbedded

with

a

reinforcing

phase

suchasfibersorpowdersInaPMC,thestartingmaterialsare: Apolymer

A

reinforcing

phase

thecomposite FRPcompositescanbedesignedwithveryhigh

s reng

owe g an

mo u us

o

we g ra os

Thesefeaturesmakethemattractiveinaircraft,cars,trucks,boats,andsportsequipment


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commonmatrix

materials

the

principal

TS

polymersare:

Phenolics usedwithparticulatereinforcingphases

Polyestersand

epoxies

more

closely

associated

with

s

Thermoplasticmoldingcompoundsarecomposite

Mostelastomersarecompositematerialsbecausenearl allrubbersarereinforcedwithcarbonblack


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ReinforcingAgent

Possible

geometries

fibers,

particles,

and

flakesPossiblematerialsceramics,metals,otherpolymers,

Particlesandflakesareusedinmanyplasticmolding

compoundsOfmostengineeringinterestistheuseoffibersasthe

reinforcingphase

ommon

er

ma er a s:

g ass,

car on,

an

ev ar

apolymer)

The canbeshortorlon basedonre uirement


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Prepregs

Fibersimpregnated

with

partially

cured

TS

resins

to

facilitateshapeprocessing

Avai a eastapesorcrossp ie s eetsor a rics

Curing

is

completed

during

and/or

after

shaping

vantage:prepregs are a r cate w t cont nuousfilamentsratherthanchoppedrandomfibers,thusincr asin str n thandmodulus

Moldcompounds shortfibers


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Classification of manufacturing processes for FRP


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pen

o

rocessesFamil ofFRPsha in rocessesthatuseasin le

positiveor

negative

mold

surface

to

produce

laminated

FRPstructures

Thestartingmaterials(resins,fibers,mats,andwoven

rovings)

are

applied

to

the

mold

in

layers,

building

up

Thisisfollowedbycuringandpartremoval

epoxies,usingfiberglassasthereinforcement


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Handlayup:(1)moldistreatedwithmoldreleaseagent;(2)thingel, ,

(3)when

gel

coat

has

partially

set,

layers

of

resin

and

fiber

are

applied,thefiberisintheformofmatorcloth;eachlayerisrolledtoimpregnatethefiberwithresinandremoveair;(4)partiscured;(5)u y ar ene partisremove rommo


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OpenMoldFRPProcesses

1. Hand

lay

up

2. Sprayup

3. Automatedtapelaying machines

The

differences

are

in

the

methods

of

applying

the

am nat onstot emo ,a ternat vecur ngtechniques,andotherdifferences

,

swimmingpools,largecontainertanks,stageprops,radomes,andotherformedsheets


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pray

p e oLiquidresinandchoppedfibersaresprayedontoan

Itis

an

attempt

to

mechanize

application

of

resin

fiber

layersandreducelayuptime

Itisanalternativeforstep(3)inthehandlayup

procedure


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Automatedtapelaying machine

courtes CincinnatiMilacron


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CuringinOpenMoldProcesses

Curing

is

required

of

all

thermosetting

resins

used

in

FRPlaminatedcomposites

Curingcrossin s t epo ymer,trans ormingit romitsliquidorhighlyplasticconditionintoahardened

Threeprincipalprocessparametersincuring:

1. Time

2. Temperature

3. Pressure


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CuringMethodsthatUseHeating

Ovencuringprovides

heat

at

closely

controlled

temperatures;somecuringovensareequippedtodraw

Infraredheatingcanbeusedinapplicationswhereitisimpractical

to

place

the

molding

in

an

oven

Curinginanautoclaveprovidescontroloverbothtemperatureandpressure

and/orpressure

at

controlled

levels

InFRPcompositesprocessing,itisusuallyalargeor zon a cy n erw oorsa e eren


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Performedinmoldsconsistingoftwosectionsthat

Advantagesof

aclosed

mold

are:

,

(2) closercontrolovertolerances,and

Threeclassesbasedontheircounterpartsinconventional lasticmoldin :

1. Compressionmolding

2. Transfermolding.


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ompress on

rocesses

lowermold

section,

and

the

sections

are

brought

togetherunderpressure,causingthechargetotaketheshapeofthecavityTransfermolding:Achargeofthermosettingresinwith

, ,squeezedbyramactionintooneormoremoldcavities

n ec on o ng Conventionalinjectionmolding


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ReinforcedReactionInjection

Molding

ingredients

are

mixed

and

injected

into

amold

cavitywherecuringandsolidificationoccurduetoc em ca react onrat ert an eat

Reinforcedreactioninjectionmolding(RRIM)isafibers,typicallyglass,inthemixture

Advantages:similartoRIM(e.g.,noheatenergy

requ re ,

owercos

mo ,

w

ea e

ene

offiberreinforcement

Products:autobod andtruckcaba licationsforbumpers,fenders,andotherbodyparts


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Resinimpregnated continuousfibersarewrappedaroundarotatingmandrelthathastheinternalshapeofthedesiredFRPproduct;theresinisthencuredandthemandrelremoved

Thefiberrovings arepulledthrougharesinbathimmediatelybeforebein woundinahelical atternontothemandrel

Theoperationisrepeatedtoformadditionallayers,eachhaving

a

criss

cross

pattern

with

the

previous,

until

the

desired

part

(a)Helical(b)polar


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PultrusionProcesses

Similar

to

extrusion

(hence

the

name

similarity)

but

workpieceispulledthroughdie(soprefix"pul"in" " x

Likeextrusion,pultrusionproducescontinuous

Developedaround1950formakingfishingrodsofglassfiberreinforcedpolymer(GFRP)

Arelated

process,

called

pulforming,

is

used

to

make

partsthatarecurvedandwhichmayhavevariationsincrosssectiont roug outt eir engt s


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Pultrusion

Continuous

fiber

rovings

are

dipped

into

a

resin

bath

andpulledthroughashapingdiewherethe

Thesectionsproducedarereinforcedthroughouttheir

Likeextrusion,thepieceshaveaconstantcrosssection,whoseprofileisdeterminedbythe

shapeof

the

die

opening

Thecuredproductiscutintolongstraightsections


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Pultrusion rocess


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Pulforming

Pultrusion

with

additional

steps

to

form

the

length

into

asemicircularcontourandalterthecrosssectionat

Pultrusionislimitedtostraightsectionsofconstant

Thereisalsoaneedforlongpartswithcontinuousfiberreinforcementthatarecurvedratherthan

straightand

whose

cross

sections

may

vary

throughoutlength

u orm ng ssu te tot ese essregu ars apes


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Pulforming process


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OtherPMCShapingProcessesCentrifugalcasting

Tuberolling

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11 Polymer Composite Processing

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