Terephthalate-co-bibenzoate polyesters

Copolyesters are based on a diacid component containing terephthalate and 4,4'-biphenyl dicarboxylate or 3,4'-biphenyl dicarboxylate, and a diol component containing an alkylene diol, e.g., ethylene glycol or NPG, and an alicyclic polyhydroxyl compound, e.g., CHDM. The copolyesters may have a glass transition temperature more than 100 DEGC and mechanical, thermal and/or barrier characteristics atleast comparable to some commercially available copolyesters. A method to control the morphology and properties of a copolyester involves contacting diacid and diol components in the presence of a catalyst, selecting proportions of terephthalic and 4,4'-biphenyl dicarboxylic or 3,4'-biphenyl dicarboxylic acids or ester producing equivalents thereof in the diacid component, and selecting the alkylene diol and proportions of the CHDM (or other alicyclic polyhydroxyl compound) and the alkylene diol in the diol component, to obtain the desired morphology and other properties.