08 thermoplastic engineering (1).ppt

8/13/2019 08 thermoplastic engineering (1).ppt

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Thermoplastic Materials

Engineering Plastics

MFG 355


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Engineering Thermoplastics

Replace metallic parts

Strength and stiffness

Retention of properties over range of temperatures

Toughness to ithstand incidental damage !imensional sta"ilit#

$o creep

$o %TE

&ithstand environmental factors '()* +,* chemicals-

Shaped easil#


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Engineering Thermoplastics

%ompared to commodit# plastics

More e.pensive

The commodit# resins are all lac/ing some

critical propert#

Some Engineering Thermoplastics are formed

through the condensation pol#meri0ation

process


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Pol#amides or 1#lons 'P2-


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' -n

4a 4"

Pol#amides or 1#lons 'P2-

3 4a3 4"


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P2 General Famil# %haracteristics

Polarit#

%r#stallinit#

Sharp meltpoint Strength

%omparison of higher loer n#lon

num"ers


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P2 General Famil# %haracteristics

Transparent '"arel#-6coo/ in "ag 'tur/e#-

2nti7friction6not li/e PTFE "ut good

Toughness6e.cellent Fatigue resistance6e.cellent

&ater a"sorption6a ea/ness '8,7,859

6must "e dried for in:ection molding- ;ighl# cr#stalline


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1#lon


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1#lon


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1#lon


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1#lon =@ inAin

!r# it first

E.trusion $o melt viscosit#

Be careful of decomposition

Fi"ers

!raing %r#stalli0ation

+rientation


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1#lon ;istor#

1ature of pol#mer "onding not understood %arothers !ifunctional monomers Pol#mers6=>>> units long

$arger units6molecular still to eliminate ater

%ontrol of melting point and length Man# com"inations of pol#esters Tr#ing pol#amides Settling on


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2ramids


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2ramids


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2cetals or Pol#o.#meth#lenes

'P+M-


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2cetals or Pol#o.#meth#lenes

'P+M-

' -n


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2cetal General Famil#

%haracteristics Mechanical6do not em"rittle* good impact

strength Moisture6ver# little 'shoer heads- %hemical resistance6ver# high* resists stains*

sensitive to strong acids and "ases &eathering6fair Thermal6,>>oF Electrical6good Machining6li/e cutting "rass 2dhesion6epo.# glues


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Processing 2cetals

!o not heat a"ove CC>oF

Melt viscosit# is not too dependant on

temperature


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2cetal %opol#mer

'

'n


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Thermoplastic Pol#esters

'PETAPBT-


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Thermoplastic Pol#esters

'PETAPBT-

'

-n


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Thermoplastic Pol#ester General

Famil# %haracteristics

PET

;igher mechanical stiffness

Strength "# orienting chains not "# ;7"onding

Get 5>9 cr#stallinit#

forced "# mechanical stretching

PBT

cr#stalli0es rapidl#

processes faster

loer overall properties


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Processing PET

Shape it 'film* tape* fi"er* e.trude* etc-

2morphous structure

Reheat and stretch in strength direction's-

%ool to "elo Tg


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Specific TP Pol#ester T#pes

!acron fi"er6mi. ith cotton or ool7gives

permanent creases

Dodel photo film

M#lar6transparencies* tapes

PETG6gl#col modified* amorphous* li/e P)%


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Pol#car"onate


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Pol#car"onate

' -n


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;istor#

Solvent resistance '!uPont-

GE7$e.an

Properties Polar

Stiffness of "ac/"one

$ong repeat unit


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2cr#lics 'P21* PMM2-

' -n ' -n


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Properties

%olor 'transparenc#-6,> #ears A =>9

change

&eathering6"est

Mechanical properties6average e.cept

for impact '"rittle-

%hemical6chlorinated solvents attac/ it*

acetone gives it crac/s

Electrical6good


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(ses

Signs

%ounter tops6%orian

!ecorative pieces Floor a.es

Paint* fingernail polishes

%ontact lenses* glasses


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Processing

%asting 'sheets-6s#rup

?n:ection molding6good

Thermoforming6o/ "ut "rittle Machining6similar to ood


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Flouropol#mers 'PTFE* FEP* PF2-


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Flouropol#mers 'PTFE* FEP* PF2-

-n-n'

'


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;istor# of !iscover#

%ham"ers plant

Ma/ing Freon

Gas c#linder


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Properties

Most are strengthened "# the tight "ond"eteen the Fluorine and the %ar"onatoms

Slipper# 'anti7stic/ surfaces- %hemical inertness

;igh temperature melting

1on7flamma"le

;igh electrical resistance

)er# dense6,8=37,8, 'high melt viscosit#-


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(ses

+7rings

1on7stic/ surfaces

?nsulation7electrical $u"ricant

%oatings

Gears


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Processing

1ot processa"le "# e.trusion or in:ectionmolding Sintering

Put in appro. shape and heatoF

Similar to processing podered metals Fusion

Ram e.trusion %ompaction

Rods and tu"es %alendaring

)er# poor adhesion


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;igh Performance Thermoplastics


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PP+ uses

(sed to replace stainless steel for surgical

eHuipment

Replace thermosets

Pump housings

)alve components

)ideo terminal housings

'


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Pol#ar#lether/etones 'PEED* PED*

and +thers-


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Pol#sulfones 'PS( and PES-


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Pol#sulfones 'PS( and PES-


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Properties

Resistant to oils

;eat sta"ilit# '3>>oF-

%reep resistance

S+,group adds stiffness

More dimensionall# sta"le than PP+

Toughness6good


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(ses

;ot ater pipes

%offee pots

!ishasher components

2utomo"ile applications near engines

%ompete ith thermosets* "ut can "e

in:ection molded

Th l ti P l i id 'P? d


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Thermoplastic Pol#imides 'P? and

P2?-

Th l ti P l i id 'P? d


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Thermoplastic Pol#imides 'P? and

P2?-

' -n-n

'


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Properties

)er# stiff

;ighest thermal sta"ilit#

P? cannot "e melted or melt processed P2? can "e 'Torlon-

P? is sintered ')espel-

P? film is cast as monomers and heated topol#meri0e 'Dapton-


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(ses

P? is used in circuit "oards

;igh temperature parts

$o friction "earings* sliding parts

Gears


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%ellulosics


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%ellulosics

1itrocellulose

Gun cotton

%ellulose nitrate

$acHuers and plastics


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T#pes of %ellulosics

Ra#on

)iscose process

%ellophane

Meth#l cellulose

Filler

Edi"le


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Than/ Iou


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1#lon ;istor#

%arothers

?oa6BS

?llinois6Ph!

;arvard6Teach

!uPont6"asic research

Pol#phen#lenes 'PPE PP+ and


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Pol#phen#lenes 'PPE* PP+* and

PPS-

%

%

%

%

%

%

%

%

+;;

;

; ;

;

;

;

;;

PP+

08 thermoplastic engineering (1).ppt

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