Abstract: The present disclosure relates to a process for preparing polyester. The process for preparing the polyester essentially involves the preparation of the isosorbide oligomer and the isosorbide polymer from the isosorbide oligomer. The isosorbide oligomer or isosorbide polymer is then co-polymerized with the polyester. The copolymerization isosorbide oligomer or isosorbide polymer may be carried out at any stage of the preparation of the polyester. The polyester obtained in accordance with the process of the present disclosure can be used in packaging applications such as preparing packaging materials or containers. The material or container obtained from the polyester of the present disclosure is capable of withstanding a temperature of 60 to 90° C. without undergoing any deformation and shrinkage. Further, the material or container obtained from the polyester of the present disclosure is transparent or has lower color b* value.

Abstract: A method of forming a polymer includes polymerizing a first pre-polymer, produced by the reaction of a dicarboxylic acid, or ester thereof with a first alkylene diol; with a second pre-polymer produced by the reaction of an aromatic sulfonate or a salt thereof, or ester thereof, with a second alkylene diol; to form a metal sulfonate co-polymer; reacting the metal sulfonate co-polymer with a fast crystallizing polyester block having a degree of polymerization of at least about 20 to provide an amorphous sulfonated co-polyester; and crystallizing the amorphous sulfonated co-polyester to form a crystallized sulfonated co-polyester.