Processing of polyesters

摘要

Process for improving mechanical properties of an aged polyester composition consisting essentially of copolymer of hydroxybutyrate units and hydroxyvalerate units which comprises heating the polyester at a temperature whereby (i) the polyester is restored to its original non-aged properties, and (ii) subsequent ageing of the polyester is retarded as indicated by substantial improvement of at least one measurement indicative of ageing compared to non heat treated polyester of the same age. The invention includes the polyester composition and shaped articles which have been subjected to the process and in which ageing is retarded.