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Chapter 27 843
Copyright © 2017 Pearson Education, Inc.
41.
Rubber contains cis double bonds. Ozone
(
O
3
)
, which is present in the air, oxidizes double bonds to carbonyl
groups, which destroys the polymer chain. Polyethylene does not contain double bonds, so it is not air-oxidized.
O O
H
O
3
42.
2
CH
2
CH CH
CH
O
acrolein
repeating unit
acrolein
repeating unit
2
CH CH
O
CH
CH
2
CH CH
O CH
CH
O
43.
The plasticizer that keeps vinyl soft and pliable can vaporize over time, causing the polymer to become
brittle. For this reason, high-boiling materials are preferred over low-boiling materials as plasticizers.
44.
a.
Because the negative charge on the propagation site can be delocalized onto the carbonyl oxygen, the
polymer is best prepared by anionic polymerization.
O
C
C
CH
3
CH
2
O
CH
2
CH
COO
−
O
C
C
CH
3
CH
2
O
CH
3
CH
2
CH
2
CH
2
Li
Bu
NO
2
NO
2
CH
2
CH
COO
−
CH
2
CHCH
2
CHCH
2
CHCH
2
CH
CH
3
C COO
−
C
O
O
NO
2
NO
2
O
O
CH
2
CHCH
2
CHCH
2
CHCH
2
CH
CH
3
COO
−
COO
−
COO
−
HO
−
H
2
O
CH
3
CH
3
COO
−
COO
−