Study on phase transition and crystallization behavior of a monotropic liquid crystalline poly(ester-imide)

A poly(ester-imide) was synthesized from N-(10-carboxydecanyl) trimellitic imide and methylhydroquinone diacetate via melt transesterification condensation. It was characterized through thermal analysis, optical microscopy, wide-angle X-ray diffraction, and oscillatory rheometry. The poly (ester-imide) showed a monotropic mesophase transition behavior. The mesophase was identified as a nematic one from a unique hysteresis of viscoelastic properties. The crystallization behaviors in the isotropic melt phase and nematic mesophase were compared. They showed the same crystal structure and Avrami exponent value for crystallization. But the crystallization velocity was faster in the nematic phase. The crystal grown from the nematic phase showed a higher melting temperature than that grown from the isotropic phase.