Structure and properties of fully aromatic thermotropic liquid-crystalline copolyesters containing m-hydroxybenzoic acid units

2003-12-13
Yerlikaya, Z
Aksoy, S
Bayramlı, Erdal
A series of fully aromatic copolyesters based on p-acetoxybenzoic acid (p-ABA), hydroquinone diacetate (HQDA), terephthalic acid (TPA), and m-acetoxybenzoic acid (m-ABA) were prepared by a modified melt-polycondensation reaction. The copolyesters were prepared in two series in which series I is based on a two monomer system (p-ABA/m-ABA) and series II is based on a three monomer system (HQDA/TPA/m-ABA). The effect of different linear structures and kink moiety on the properties of the copolyesters were investigated systematically. The copolyesters were characterized by differential scanning calorimetry, thermogravimetric analysis, H-1-NMR, polarized optical microscopy, X-ray diffraction, and intrinsic viscosity measurements. It was found that the copolyesters exhibited nematic liquid-crystalline phases when the content of linear (p-ABA or HQDA/TPA) units was over 67 mol %. The melting or flow-transition temperatures were decreased with an increase of the content of kink m-ABA units. The copolyesters that contained p-ABA as linear units had a significantly higher degree of crystallinity compared to the copolyesters that contain HQDA/TPA as the linear units, implying a higher blockiness in the polymer chains as a result of the higher reactivity of the p-ABA units in the p-ABA/m-ABA system. All the copolyesters had poor solubility except the copolyesters containing at least 40 mol % of m-ABA, which were soluble in a dichloromethane/trifloroacetic acid (70:30 v/v) mixture. (C) 2003 Wiley Periodicals, Inc.
JOURNAL OF APPLIED POLYMER SCIENCE

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Citation Formats
Z. Yerlikaya, S. Aksoy, and E. Bayramlı, “Structure and properties of fully aromatic thermotropic liquid-crystalline copolyesters containing m-hydroxybenzoic acid units,” JOURNAL OF APPLIED POLYMER SCIENCE, pp. 3260–3269, 2003, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/63293.