chapter polymer science
TRANSCRIPT
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Chapter 7
Fundamentals of Polymer Science
Paul C. Painter
Michael M. Coleman
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1st -Or der Tr ans it ions
GasGas
LiquidLiquid
SolidSolid((Crystalline)Crystalline)
Sma ll M olecules
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Many Materials form metastable glasses -
what about polymers like PET, atactic polystyrene?
Two Possibilities; Observed Behaviordepends on:
StructureCooling Rate
Crystallization Kinetics
Glass Transition
Liquid
Gas
Glass
Crystal
TR Tf Tb
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No Gaseous StateNo Gaseous State
Liquid State - - Viscoelastic MeltLiquid State - - Viscoelastic Melt
Semi- CrystallineSemi- CrystallineSolidSolid
ElastomerElastomerSemi- SolidSemi- Solid
(like Silly Putty)(like Silly Putty)
GlassGlass
Cool CoolCool +
X- link
Cool
Also:x-link ed r ub ber + solvent (gel)
liquid cr ysta lline polymer s, etc.
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~ 1500 Columbus Stumbles Across Haiti~ 1600 Missionaries Observe Indians Making Crude
Rubber Shoes (Caoutchouc)
1700 Joseph Priestly Invents a Name
1820 1st Rubber Shoes1832 Mackintosh
1833 Goodyear Starts Work on Rubber
1844 Vulcanization
1875 Henry Wickham -- Pirate or Con-Man?1922 Stevenson Plan
1942 Synthetic Rubber Project
1988 Penn State Rubber Project
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Material Derived from Trojan-Enz
Samples Cut Out With a Dog Bone Cutter
Test -- Tensile Elongation (1 cm per minute)
UniaxialDeformation
~ 1,000 %
Biaxial
Deformation~ 300 %
Estimated Burst
Pressure ~ 57 psi
~ 4 atm.
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The Issues
Bonding & the Forces between Chains
Conformations
Ordered
Disordered
Stacking or Arrangement of Chains in
Crystalline Domains
Morphology of Polymer Crystals (and
Things like Block Copolymers)
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Interaction Energy Depends Upon the BalanceBetween Attractive and Repulsive Forces
Attractive Forces
Type of
In ter act ion C ha r acter istics
Approximate
Strength
Dispersion Forces
Dipole / dipole
(Freely Rotating)
Short Range
Varies
as 1/r6
~0.2 to 2
kcal./mole
Strong Polar Forces
& Hydrogen Bonds
Complex Form,
but Short Range
~ 1 to 10 kcal. /
mole
Coulombic, as Found
in Ionomers
Long Range,
Varies 1/r
~ 10 to 20 kcal./
mole (?)
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In ter action between fluctua ting dipoles whose
aver age value is zer o (!)
eg: simple hydr ocar bons
Dispersion Forces
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CH 2CH
C
N
+
CH 2 CH
C
N
+
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Schemat ic
Diagramof Cluster s
in a n
Ionomer .
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Hydrocarbons -- PE, IPP, PS, etc.
Weak Dispersion Forces
Polar Polymers -- PVC, PAN, etc.
Eg: Those Containing Heteroatoms (O, N, Cl, F) --
Dipole/dipole Interactions Hydrogen Bonding Polymers
Eg: Nylons, Polyurethanes, etc.
Ionomers
Eg: Surlyn
IncreasingIncreasing
InteractionInteraction
StrengthStrength