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Polymer SynthesisCHEM 421
Reading (Odian Book):
Chapter 1-4, 1-5, 1-6
Polymer SynthesisCHEM 421
Polymer Parameters
• Chemical structure– Chemical composition and distribution
– Sequence length and distribution
• Molecular weight and distribution
• Chain isomerism
• Morphology
• Topology
• Additives
• Cost
Polymer SynthesisCHEM 421
Chain Isomerism
• Regio-isomers
• Geometric isomers
• Stereo-isomers
• Conformational isomers
Polymer SynthesisCHEM 421
Conformational Isomers
H
P
HPH
P
H
P
H
Polymer SynthesisCHEM 421
Conformational Isomers
- 180 - 120 - 60 0 +60 +120 +180
En
erg
y (k
cal/m
ol)
H
P
HP
3.8
1.0
4.5
H
Cl
HCl
HH
Polymer SynthesisCHEM 421
Amorphous Morphology
Glass Transition Temperature
Polymer SynthesisCHEM 421
Polymer SynthesisCHEM 421
Copolymer Synthesis
Tetrafluoroethylene(TFE)
2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole
(PDD)
Udo, M.; Resnick, P.; Kipp, B. ; DeSimone*, J.M. Macromolecules 2003, 36, 7107
50
100
150
200
250
300
350
50 60 70 80 90 100
Tg in
°C
PDD in wt-%
Polymer SynthesisCHEM 421
Mechanical Properties
• Tensile strength– Resistance to stretching
• Compressive strength– The extent to which a sample can be compressed
before it fails
• Flexural strength– Resistance to breaking or snapping when bent
• Impact strength–Measure of toughness, ability to withstand sudden
impact
• Fatigue– Ability to withstand repeated tensile, flexural or
compressive stress
Polymer SynthesisCHEM 421
Mechanical Properties
• Tensile stress (σ)
– σ = F / A
– dynes per square cm
• Tensile strain (ε)
– ε = ΔL / L
• Tensile Modulus (E)
– E = σ / ε
Polymer SynthesisCHEM 421
Polymer SynthesisCHEM 421
Processing of Amorphous Polymers
Tprocessing = ?
Polymer SynthesisCHEM 421
Symmetry Requirements forCrystallinity
Ph Ph
... ...Ph
Ph PhPh
Syndiotactic Polystyrene
Ph Ph
... ...Ph
Ph Ph Ph
Atactic Polystyrene
Tm = N/A
Tg = 105 °C
Tm = 270 °C
Tg = 105 °C
Polymer SynthesisCHEM 421
• Cool a polymer melt…
–Translational, rotational and vibrational motions decrease…
– If certain symmetry elements are met, crystallization can take place just below Tm
–Continue to cool, long-range backbone segmental motion ceases at Tg
–Side groups and backbone para-phenylene still in motion below Tg
Processing of Semicrystalline Polymers
Polymer SynthesisCHEM 421
Trashcan
CH2 CH
CH3n
Tg = - 20 °C
Tm = 170 °C
Isotactic Polypropylene
Polymer SynthesisCHEM 421
Processing of Semicrystalline Polymers
Tprocessing = ?
Polymer SynthesisCHEM 421
Processing of Semicrystalline Polymers
Polymer SynthesisCHEM 421
Differential Scanning Calorimetry
Polymer SynthesisCHEM 421
DSC of a Crystalline Polymer
En
dE
nd
oo
Polymer SynthesisCHEM 421
DSC of a Crystalline Polymer
