11 Polymer Composite Processing
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Transcript of 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