Premium
A Further Study on the Crystallization and Melting Behavior of Liquid Crystalline Copolyesters Based on Modified Poly[( p ‐hydroxybenzoic acid)‐ co ‐(ethylene terephthalate)]
Author(s) -
Liu Yongjian
Publication year - 2001
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20010701)202:11<2300::aid-macp2300>3.0.co;2-p
Subject(s) - differential scanning calorimetry , copolyester , crystallization , crystallinity , materials science , terephthalic acid , polymer chemistry , ethylene , enthalpy of fusion , melting point , chemical engineering , crystallography , polyester , composite material , chemistry , organic chemistry , thermodynamics , physics , engineering , catalysis
In a previous investigation of the crystallization and melting behavior of liquid crystalline PET/HBA/HQ/TPA copolyesters, which were prepared by the incorporation of p ‐hydroxybenzoic acid (HBA), hydroquinone (HQ), and terephthalic acid (TPA) into poly(ethylene terephthalate) (PET), we reported that they are more crystalline than PET/HBA copolyesters. Introduction of HQ/TPA disrupts longer rigid‐rod sequences formed by HBA, enhancing macromolecular motion and increasing crystallization rate and crystallinity. In particular, PET/HBA/HQ/TPA copolyesters may also exhibit two endothermic fusion peaks under certain crystallization conditions. This paper is a further study of the crystallization and melting behavior of a PET/HBA/HQ/TPA copolyester with molar ratio of 40/20/20/20. The double‐peak differential scanning calorimetry melting endotherms from isothermally‐crystallized samples have been scrutinized in terms of two hypotheses: (i) they are associated with two distinct morphologies or crystals; (ii) they are related to melting and recrystallization effects. Our data from a combination of differential scanning calorimetry, wide angle X‐ray diffraction, and density techniques support the second hypothesis, and are not consistent with the first one.