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Structure and properties of fully aromatic thermotropic liquid crystalline copolyesters containingm hydroxybenzoic acid units      
Yazarlar
Prof. Dr. Zekeriya YERLİKAYA Prof. Dr. Zekeriya YERLİKAYA
Kastamonu Üniversitesi
S Aksoy
E Bayramli
Özet
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, 1H-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. © 2003 Wiley Periodicals, Inc.
Anahtar Kelimeler
Liquid-crystalline polymer | Polycondensation | Structure | Thermal properties | X-ray
Makale Türü Özgün Makale
Makale Alt Türü SSCI, AHCI, SCI, SCI-Exp dergilerinde yayımlanan tam makale
Dergi Adı JOURNAL OF APPLIED POLYMER SCIENCE
Dergi ISSN 0021-8995
Dergi Tarandığı Indeksler SCI
Makale Dili İngilizce
Basım Tarihi 12-2003
Cilt No 90
Sayı 12
Sayfalar 3260 / 3269
Doi Numarası 10.1002/app.12985
Makale Linki http://doi.wiley.com/10.1002/app.12985