Polyesters including isosorbide as a comonomer and methods for making same

A method for making a polyester polymer comprising:

• (1) combining in a reactor a monomer comprising a terephthaloyl moiety;
• optionally, one or more other monomers containing an aromatic diacid moiety;
• a monomer comprising an ethylene glycol moiety;
• a monomer comprising an isosorbide moiety;
• optionally, one or more other monomers comprising a diol moiety;
• and optionally, a monomer comprising a diethylene glycol moiety, with a condensation catalyst suitable for condensing aromatic diacids and glycols;
• and
• (2) heating said monomers and said catalyst to a temperature sufficient to polymerize said monomers into a polyester polymer having at least terephthaloyl moieties, ethylene glycol moieties nd isosorbide moieties;
• wherein said heating is continued for a sufficient time to yield an isotropic polyester having an inherent viscosity of at least about 0.35 dL/g when measured as a 1% (weight/volume) solution of said polyester in o-chlorophenol at a temperature of 25.degree. C.