AROMATIC AND HETEROATOMIC POLYESTERS .2. THE EFFECT OF A RANGE OF DISRUPTING UNITS ON POLYESTERS BASED ON PHENYLENE AND NAPHTHYLENE GROUPS

The liquid-crystalline polyester (designated P(R)), synthesized from h ydroquinone diacetate, terephthalic acid and 6-acetoxy-2-naphthoic aci d (1:1:2) by melt-phase transesterification, may be considerably modif ied in properties by the replacement of one or more of the monomers by a 'disrupting' unit. The disruption may be angular, as for example wh en isophthalic acid replaces terephthalic acid, or 2,7-diacetoxynaphth alene replaces hydroquinone diacetate, or it may be lateral, as when 1 ,5-diacetoxynaphthalene is used. The effects of these disrupting units on the thermal behaviour of the polymers, especially liquid crystalli nity, and on their propensity to form fibres, are discussed. Although liquid crystallinity may be observed when the polymers are formed from up to 50% of angular units, the fibre formation is significantly dimi nished whenever the acetoxynaphthoic acid is replaced by p-acetoxybenz oic acid.