Chemistry Reference
In-Depth Information
Wholly aromatic polyesters are produced for high temperature applications. The materials must
also have good abrasion resistance. One such commercial polyester
is prepared from
p
-
hydroxybenzoic acid:
O
O
n
p
0
-biphenol, and terephthalic
Another one is a copolyester prepared from
p
-hydroxybenzoic acid,
p
,
or isophthalic acids:
O
O
O
O
O
O
n
The above shown polyester does not melt and decomposes at 550
C.
Turner et al. [
38
] reported preparation of triptysene containing polyesters. These polyesters were
illustrated as follows:
O
O
O
O
O
O
x
where
2,4, or 6.
The polyester was prepared by melt-phase synthesis by a transesterification reaction. Higher
thermal stability was claimed for the polyesters containing triptysene than the analogous polyesters
without it.
The properties of various polyesters were summarized by Wilfong [
15
]. Table
7.1
presents
x ΒΌ
T
m
and
T
g
values of some polyesters based on information from Wilfong and other sources in the
literature.
Among new methods of forming polyesters is a preparation of completely aromatic polyesters by
direct condensation of hydroxyaromatic acids (like hydroxybenzoic) with the aid of triphenylpho-
sphorous compounds or dichlorophenylphosphine [
38
]:
HO
O
O
N
O
O
+
P
n
3
OH
Hexachlorotriphosphatriazine
can also be used to attain direct polycondensations of
hydroxybenzoic acid [
43
].
