Synthesis and rheological investigation on phase behaviors of semiflexible type amorphous liquid crystalline poly(ester-imide)s

Abstract

Main chain type thermotropic poly(ester-imide)s composed of N-(omega-carboxyalkylene) trimellitic imides and methylhydroquinone diacetate or hydroquinone diacetate were prepared by melt transesterification condensation. DSC and polarized light microscopy observation revealed that polymers made from hydroquinone diacetate showed both crystal melting and mesophase to isotropic phase transition but those from methylhydroquinone diacetate showed only mesophase to isotropic phase transition. The amorphous type liquid crystalline polymers showed extremely slow crystallization velocities. The mesophase of all polymers was verified as a nematic one from the drops of moduli and viscosities at the isotropic to mesophase transition during cooling. For an amorphous liquid crystalline polymer the changes of dynamic rheological properties were checked around the mesophase to isotropic phase transition. Both isotropic and nematic phases succeeded in time-temperature superposition but biphase failed. (C) 2000 Elsevier Science Ltd. All rights reserved.