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Thermotropic liquid crystalline copolyesters. II. Synthesis and thermal characterization of copolyesters of terephthalic acid, methyl hydroquinone and 1,4‐butane diol
Author(s) -
Rath Asoke K.,
Selvaraj Leena,
Ponrathnam Surendra
Publication year - 1991
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.4990240405
Subject(s) - copolyester , thermotropic crystal , terephthalic acid , diol , liquid crystal , mesophase , materials science , hydroquinone , butane , glass transition , polymer chemistry , mesogen , organic chemistry , polymer , polyester , chemistry , catalysis , liquid crystalline , composite material , optoelectronics
The synthesis and thermodynamic evaluations of a series of random copolyesters based on terephthalic acid, methyl hydroquinone and 1,4‐butane diol are presented. The copolyester composition was varied by altering the relative concentrations of methyl hydroquinone and 1,4‐butane diol. The copolyesters display thermotropic transitions. The enthalpy changes during mesophasic transition display a minimum corresponding to equimolar composition. The copolyester with 75 mol% of spacer diol exhibited the lowest nematic transition temperature (190‐6°C). At this composition the nematic mesophase was most stable (δ T N = 115‐6°C). ΔH N‐1 and ΔS N‐1 decrease with increasing rigid diol content. The isotropization temperatures were almost comparable since the largest mesogenic residues are similar in aspect ratio. These residues are required to melt prior to isotropization.