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Polymer molecules. □ Molecular structures & configurations. □ Copolymers. □ Polymer crystallinity. Hydrocarbon molecules ... Chemistry of polymers.
Typology: Exams
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Ä4-bonds, but only 3 atoms bound to C’s
H C C C C C C C C
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H = H 3 C CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3
H 3 C CH
CH 3 CH 2 CH CH 2
CH 3
CH 3
4
Free radical polymerization
Initiator: example - benzoyl peroxide
C
H
H
O O C
H
H
C
H
H
2 O
C C
H H
H H monomer (ethylene)
R +
free radical
R C C
H
H
H
H
initiation
R C C
H
H
H
H
C C
H H
H H
H
H
H
H
C C
H H
H H
propagation
dimer
= 2R
Polyethylene (PE)
mer
Cl Cl Cl
Polyvinyl chloride (PVC)
mer
Polypropylene (PP)
mer
Linear Branched Cross-Linked Network
secondarybonding
Direction of increasing strength
Homopolymer: same type of mer units along a chain
Copolymers: two or more different mer units
Copolymers have four types
Arrangement of molecular chains in a unit cell for polyethylene
region
amorphous region
