Investigation of physical state and phase behavior of polyester‐imides

Abstract

AbstractChanges in properties of linear aromatic heterocyclic polymers of the polyimide class after introduction of ester linkages into their dianhydride component and of the oxygen and sulfur atoms into their diamine component have been studied. Thermomechanical, dilatometric, thermographic characteristics and x‐ray diffraction patterns of poly(ester amic acids) and polyester‐imides have been investigated. On heating, poly(ester amic acids) and amorphous polyesterimides exhibited a peculiar effect of self‐orientation of macromolecules. The x‐ray diffraction patterns of unoriented films indicate that they exhibit axial‐planar texture with the c axis of macromolecules in the film plane. The formation of the texture is preceded by mutual arrangement of macromolecules, i.e., by a precrystallization process beginning in the amorphous state. Because of this, on heating at temperatures ranging from 200 to 380°C, polyester‐imides yield highly crystalline products. Crystallographic parameters of the polymer lattices on x‐ray diffraction patterns and dichroism of absorption bands in polarized infrared spectra, the most probable conformations of macromolecules of some polyesterimides are proposed.