Chemistry Reference
In-Depth Information
R
3
CO
2
CO
2
C
6
H
5
HO
CO
2
C
6
H
5
O
CO
x
POB
H
3
CCO
2
CO
2
SiMe
Me
3
SiO
COCl
HO
HO
CO
2
H
CO
2
H
6-Hydroxy-Z-naphthaoic acid
4-Hyroxybiphonyl-4-carboxylic acid
HO
CH
CH
CO
2
H
HS
CO
2
H
4-Mercaptrobenzoic acid
4-Hyroxycinnumic acid
HO
CH
N
CO
2
H
N-(4'-hydroxybenzyidene)-4-amino-benzoic acid
Formula 14.4
In addition to homopolyesters, a large number of copolyesters of 4-HBA were
prepared by numerous research groups. These copolycondensations may be sub-
divided into three categories:
(I)
Cocondensations yielding liquid crystalline (LC) copolyesters, which may be
processed from the nematic phase below 400 C.
(II)
Copolycondensations
yielding
crystalline
copolyesters
which
decompose
upon melting.
(III) Copolycondensations yielding almost neat POB
LC copolyesters were usually prepared by cocondensation of 4-HBA and
comonomers in bulk, in the molten state, and thus, do not deserve further dis-
cussion in this chapter. Yet, it should be mentioned that several nematic copoly-
esters
were
commercialized
under
various
trademarks.
Numerous
crystalline
