Abstract: It has been determined that the mechanical and thermal properties of polyesters can be improved by incorporating hydroxyalkyl trimellitic imides therein. Such polyesters are comprised of repeat units which are derived from (a) at least one diacid component, (b) at least one diol component, and (c) at least one hydroxyalkyl trimellitic imide.

Abstract: Polyethylene naphthalate is a polyester resin that is highly useful in numerous applications. For instance, polyethylene naphthalate can be molded into a wide variety of products which have outstanding properties. However, polyethylene naphthalate does not crystallize rapidly at temperatures which are normally used in molding operations. This invention discloses a modified polyethylene naphthalate which crystallizes rapidly at much lower temperatures than does polyethylene naphthalate homopolymer. The modified polyethylene naphthalates of this invention contain a small amount of polyether glycol. This invention more specifically relates to a polyester comprised of repeat units which are derived from (a) a naphthalate dicarboxylic acid and (b) a diol component which is comprised of (1) at least one glycol containing from 2 to 12 carbon atoms and (2) from about 1 to about 12 weight percent of at least one polyether glycol based upon the total weight of the polymer.