Chemistry Reference
In-Depth Information
Table 7.1
(continued)
Dicarboxylic acid
T
g
(
C)
T
m
(
C)
Glycol
HOCH
2
CH
2
OH
-
132
HOOC
COOH
<
80
226-232
HOCH
2
CH
2
CH
2
OH
HOOC
COOH
-
154-161
HO-(-CH
2
-)
6
-OH
HOOC
COOH
<
45
129-132
HO-(-CH
2
-)
8
-OH
HOOC
COOH
<
25
130-138
HO-(-CH
2
-)
10
-OH
HOOC
COOH
-
152
HOCH
2
CH
2
OH
HOOC
O
2
173
283
HOOC
COOH
HO
O
2
150
348
HOOC
COOH
HO
CH
2
2
279
330
HOOC
COOH
O
HO
2
S
O
164
315
HOOC
COOH
OH
HO
From various sources in the literature
7.2.2 Linear Unsaturated Polyesters
The materials in this group are linear copolyesters. One of the dicarboxylic acids is an aliphatic
unsaturated diacid. The unsaturation is introduced into the polymer backbone for the purpose of
subsequent cross-linking. Unsaturated polyester technology was developed for use in glass fiber
laminates, thermosetting molding compositions, casting resins, and solventless lacquers.
Propylene glycol is often used as the diol. To a lesser extent are also used other glycols, like
diethylene glycol, for greater flexibility, or neopentyl glycol for a somewhat better thermal resistance.
Bisphenol A (2,2 bis(4-hydroxyphenyl) propane) is used when better chemical resistance is needed.
Use of mixed diols is common. Many unsaturated dicarboxylic acids can be used, but maleic (as an
anhydride) or fumaric acids are the most common. Chloro maleic or chloro fumaric acids are also
employed.
