5MPK -Composite.pdf

8/14/2019 5MPK -Composite.pdf

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Inorganic Materials

- Composite


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st

Listed as one of the top 10 greatest

of the 20th

Century ers: po o moon an ng, unmanne

satellites, microprocessor, CAD, CT scan,

-, , ,genetic engineering


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matrix that surrounds and holds in place.

The material consists of two (or more) phases

The other phase is discontinuous (the

The phases can be thought of as a group of


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Constituents of composite materials

.

Continuous phase, the primary phase.It holds the dispersed phase and shares a load with it.

. sperse re n orc ng p aseThe second phase (or phases) is imbedded in the matrix in a

continuous/discontinuous form.Dis ersed hase is usuall stron er than the matrix therefore it is sometimescalled reinforcing phase.

3. Interface

, ,mechanical)


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Give shape to the object

Protect the reinforcements

Weather

Impacts

Solvent/water


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properties)

(optional)


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Interface

Interface merupakan permukaan antara

reinforcement dan matriks yang menentukan

proses transfer tegangan dari matrik-reinforcement-matrik, yang berpengaruh

kepada :

- spesific strength- spesific stiffnes

- fracture toughness

- ketahanan creep


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-

Molecule entanglement adanya ikatan

matrik.

listrik secara atomik antara reinforce dan

mengakibatkan tarik-menarik, bila adagas, ikatan melemah.


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kumpulan gugus kimia yang saling.

Mechanical bonding adanya

sehingga semakin kasar permukaan

.


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Fiberglass reinforced Matrix of unsaturated polyesters and vinyl esters or

common engineering thermoplastics

Uses: tub/shower, boats, automotive, pipes,, .

Advanced

, ,reinforcements

Matrix of epoxies and specialty resins

Uses: aerospace, sporting goods, specialty


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Ceramics

Polymers

ese er, a e mos un amen a

level, in the types of bonds between the

a oms


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Metals Non-Metals

(Ionic Bonds)

o ymers

(Covalent Bonds)

Metals

(Metallic Bonds)


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,

cotton, wool, leather)

-

Polymers can be easily shaped (molded) Polymers have other advantages over

ceramics and metals


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which are linked together mono means one

mer means unit

The linked monomers form a chain-likestructure called a polymer

poly means many

The links are the covalent bonds betweenthe atoms


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HH

H C

H

HH

H C

H

H C

H C

C

H

H

H

C

H

H C

H C

C

H

H

H

C

H

C H

H

H

Monomer

C H

H

H

H

Polymer

H

Polymer


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polymeric part

Like a mass of spaghetti


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What determines physical, chemical

materials?

Molecular shape and movement

Crystallinity

Thermal transitions and crosslinks roma c y

Pendant groups

Bonding between matrix and reinforcements


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Crystal

Regions

Amorphous Semi-Cr stalline or Cr stalline

(random entanglement) (regular packing)


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Thermo lastics Thermoplastics are not crosslinked and so theywill melt

Thermoplastics are processed (molded) asmolten liquids

Thermoplastics can be re-melted repeatedly

Kitchen exam le:

candy

Examples of thermoplastics: polyethylene,, , , ,

Teflon, PET (thermoplastic polyester)


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Thermosets are crosslinked and do not melt

Crosslinking is sometimes called curing Thermosets are processed as room

Thermosets are heated to solidify

cake

xamp es o ermose s: po yes ers, v ny

esters, epoxies, phenolics, polyimides, silicones


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Thermal Transitions Heat Distortion Temperature (HDT)

ass rans on empera ure g

Melting point (Tm)

Decomposition temperature (Td)

em -crysta ne

thermoplastic HDT Tg Tm Td

Hard, stiff Leather De raded

Thermoset HDT Tg Td (Tm)

Temperature

Degraded, CharHard, stiff Semi-rigid


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good properties Good properties are

good processing Good processing is

favored by high

molecular weight

favored by low

molecular weight

perties

essing

chanicalP

r

aseofPro

c

Molecu lar Weight

Me

Molecular Weight

E


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compromise Hi h enou h molecular wei ht to et ade uate

properties

Low enough molecular weight to process OK Thermosets meet the dilemma by

crosslinking

Low molecular weight initially (for wetout andprocessing) followed by curing to increase

No compromise is required


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Pol mers Molecular sha e

Aromatic Contains the benzene group

Named aromatic because it tends to have a strongsmell like st rene

Increases stiffness

Increases strength Increases non-flammability

Aliphatic Does not contain the benzene group

Increases flexibility Increases toughness

ncreases wea era y

CCC C


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( )n

...C C C C...CC...C C...

CCC

CC

C

CCCC

C...OC

CC

CCC

C

C

C

OCC C

O

aromatic)

O

OHOHOH

C C C....C C...

C......C

H

NC

CC

C C C

CC

C

CC

CC

C

C

CC

C CC

C

OH OHCCC

C

CC

C

C

C

CC

C

C

C

CC

C

Kevlar(aromatic backbone)

.......C

Phenolic (aromatic network)


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N S S N

S N S N

+

O

...C C O

O

C...

-

+C O+ + --

C O

-O

HHPolyester is attacked by water molecules


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polar areas on other molecules. O osite char es attract

The most electronegative atoms are those

that cause polarity The electronegative atoms are: F, O, N, Cl

These are all in the upper right corner of the

per o c a e Non-polar areas attract other non-polar


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Fiber lassOH OH

Sizing (alkylsilane)

...O Si O Si O...

OH OH-

Mixed polar/non-polar

CH3

+

CH3 Nonpolar regions (weak attraction)-

....C C O C C C C C...+

Largely non-polarPolyester


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Two types of composites are:

Fiber ReinforcedCom osites

Particle ReinforcedCom osites


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constituent phases

re a ve amoun s

geometry of dispersed phase shape of particles

particle size

particle distribution

article orientation


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For a given matrix/dispersed phase system:

Concentration

Size

Shape Distribution

Orientation


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SizeShape

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