Chemistry Reference
In-Depth Information
6.13.3 Copolymers of Styrene with Maleic Anhydride
Many styrene-maleic anhydride copolymers are produced commercially for special uses. These are
formed by free-radical copolymerization and many commercial grades are partially esterified.
Molecular weights of such polymers may range from 1,500 to 50,000, depending upon the source.
The melting points of these copolymers can vary from 110 to 220
C, depending upon molecular
weight, degree of hydrolysis and esterification, and also the ratio of styrene to maleic anhydride.
Only a small percent of styrene copolymers reported in the literature achieved industrial impor-
tance. Some of the interesting copolymers of styrene that were reported but not utilized commercially
are copolymers with various unsaturated nitriles. This includes vinylidene cyanide, fumaronitrile,
malononitrile, methacrylonitrile, acrylonitrile, and cinnamonitrile [
292
]. Often, copolymerization of
styrene with nitriles yields copolymers with higher heat distortion temperature, higher tensiles, better
craze resistance, and higher percent elongation.
Styrene was also copolymerized with many acrylic and methacrylic esters. Products with better
weathering properties often form. Copolymerization with some acrylates lowers the value of
T
g
[
203
].
6.14 Polymers of Acrylic and Methacrylic Esters
There are many synthetic procedures for preparing acrylic acid and its esters. One way, used early, is
to make acrylic esters from ethylene oxide:
_
HCN
H
2
O
O
N
HO
N
35 - 40
o
C
amine catalyst
H
2
O
NH
3
_
ROH
H
2
SO
4
OR
O
O
OH
Another route is through oxidation of propylene over cobalt molybdenum catalyst at 400-500
C:
[O]
[O]
O
O
ROH
O
OH
OR
Many industrial preparations start with acetylene, carbon monoxide, and alcohol or water:
O
Ni(CO)
4
+
+
CO
ROH
OR
Ni
O
+
+
CO
ROH
OH
