Thermal Degradation of Polyesters: Part 2. Aromatic and Semiaromatic Polymers.

A detailed study was made of the thermal degradation of eight aliphatic polyesters and the results presented in Part I of this report. The results of a corresponding study of some polyesters containing aromatic rings in the polymer chain are now presented in Part II. Polyhexamethylene terephthalate degrades by the mechanism observed for aliphatic polymers--random scission and subsequent reaction of the olefinic and acid end-groups. when the acid part is aliphatic as in poly1, 4-phenylene succinate and poly1, 4-phenylene sebacate, the polymers are less stable initially than comparable aliphatic polyesters. The degradation mechanism is more complex and involves cross-linking the cross-linked sebacate product breaks down by a second degradation reaction but the succinate forms a residue which does not undergo further breakdown. jg p5