SYNTHESIS OF BISOXAZOLINES AND THEIR APPLICATION AS CHAIN EXTENDER FOR POLY(ETHYLENE-TEREPHTHALATE)

A synthetic method was found to prepare 1,2-bis-(2-oxazolinyl-2)ethane (BOXE) from succinonitrile and ethanolamine. Succinonitrile is a vici nal dinitrile, which forms with ethanolamine succinimidine. This imidi ne can be converted in good yield into the corresponding BOXE by heati ng it while stripping off the excess of ethanolamine. Bisoxazolines re act with the carboxylic endgroups of PET, giving a strong increase in viscosity. The efficiency of this chain extension reaction depends on the structure of the bisoxazoline. BOXE gives a sharp rise in the visc osity of PET after 2.5 min at 270-degrees-C. After prolonged heating t he viscosity decreases again, even under the level of the blank. A mec hanism is given which describes this unusual behaviour. It is proposed that chain scission takes places in the newly formed esteramide bridg e.