Synthesis of Oligoester α,ω‐diols by Alcoholysis of PET through the Reactive Extrusion Process

The alcoholysis of PET with diols in the presence of dibutyltinoxide was carried out in a twin‐screw extruder with residence times of 1 min and without solvent. The reaction led to scissions of PET chains and to the synthesis of oligoester α,ω‐diols with average number molecular weights of about 1000 g·mol^—1 characterised by conventional techniques such as NMR, SEC and MALDI‐TOF. The alcoholysis kinetics was studied with a rheological tool under selected conditions, and it was shown that this reaction is quite compatible with the residence times in an extruder. This study clearly shows that the oligoesters synthesised by reactive extrusion have characteristics similar to the oligoesters synthesised by batch processes over many hours. Furthermore, the melting temperature of these oligoesters can be controlled between room temperature and 220°C by using diols with different structures for the alcoholysis.