Chain extenders for polyesters. IV. Properties of the polyesters chain‐extended by 2,2′‐bis(2‐oxazoline)

摘要

AbstractSome properties of the polyesters treated with such an addition‐type chain extender as 2,2′‐bis(2‐oxazoline) (BOZ) have been investigated. The molecular size distribution and the melting point of the resultant polyesters indicate that BOZ reacts to form linear chain‐extended polymers without branching. As for their thermal stabilities, unreacted oxazoline remained in the polymer can act as a heat stabilizer by further reacting with carboxyl terminals of the polymers and by preventing decrease in the molecular weight even in the solid state. On the other hand, BOZ unit incorporated in the polyester chain was relatively thermally unstable compared with the ordinary polyester chain, especially under the polyester melt condition. The polyester treated with BOZ has a rather low carboxyl content, and considerable improvement in the hydrolytic stability has been observed. But unreacted oxazoline groups adversely affected the hydrolytic stability, although the effect was about eight times as small as that of carbox