Simultaneous Observation of Disclination and Texture by Optical Microscopy of a Thermotropic Aromatic Polyester

Abstract

An aromatic copolyester (m.p.148°C) film quenched from 180°C melt showed a schlieren texture. The birefringent domains increased in size with increasing temperature of the melt before it was quenched. The polymer film quenched from the melt after being heating above 240°C for 10 min showed both disclinations and a banded texture of random orientation on the same picture, although the banded texture can not be directly observed in the heated melt. However, the banded texture of the quenched film persisted on heating to a melt up to 200°C and began to vanish above this temperature, but the banded texture reappeared on being requenched into a solid film. The banded texture could also be seen in the localities displaying brushes. Consequently schlieren brushes are optical effects but not isotropic material regions.

Key Words:

• optical microscopy
• disclination
• schlieren texture
• aromatic polyester