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Thermal properties and crystalline structure of liquid crystalline poly(ethylene terephthalate‐ co ‐2(3)‐chloro‐1,4‐phenylene terephthalate)
Author(s) -
Rhee Do Mook,
Ha Wan Shik,
Youk Ji Ho,
Yoo Dong Il
Publication year - 2002
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.10451
Subject(s) - materials science , thermal decomposition , polymer chemistry , crystallization , phenylene , ethylene , differential scanning calorimetry , triclinic crystal system , thermal stability , crystal structure , thermogravimetry , analytical chemistry (journal) , crystallography , chemistry , organic chemistry , polymer , inorganic chemistry , catalysis , physics , composite material , thermodynamics
Thermal properties and crystalline structure of liquid crystalline (LC) poly(ethylene terephthalate‐ co ‐2(3)‐chloro‐1,4‐phenylene terephthalate) [copoly(ET/CPT)] were investigated using differential scanning calorimetry (DSC), thermogravimetry (TGA), limiting oxygen index (LOI) measurement, electron dispersive X‐ray analysis (EDX), X‐ray diffractometry, and infrared spectrometry (IR). The thermal transition temperatures of copoly(ET/CPT) were changed with the composition. Copoly(ET/CPT) showed two thermal decomposition steps and the residues at 700°C and LOI values of copoly(ET/CPT) were almost proportional to its chlorine content. The activation energy of thermal decomposition of LC units was very low compared to that of poly(ethylene terephthalate)(PET) units. Crystal structure of copoly(ET/CPT) (20/80) was of triclinic system with the lattice constants of a = 9.98 A˚, b = 8.78 A˚, c = 12.93 A˚, α = 97.4°, β = 96.1°, and γ = 90.8°, which is very close to that of poly(chloro‐ p ‐phenylene terephthlate) (PCPT) with the lattice constants of a = 9.51 A˚, b = 8.61 A˚, c = 12.73 A˚, α = 96.8°, β = 95.4°, and γ = 90.8°. When copoly(ET/CPT)(50/50) was annealed at 220°C in vacuum, crystallization induced sequential reordering (CISR) was not observed but the heat of fusion was slightly increased due to the increase of the trans isomer content in PET units. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1286–1294, 2002; DOI 10.1002/app.10451