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Structural, mechanical, and thermal properties of extruded sheets of a liquid crystalline copolyester
Author(s) -
Kyotani Mutsumasa,
Kaito Akira,
Nakayama Kazuo
Publication year - 1993
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.1993.070471115
Subject(s) - copolyester , thermotropic crystal , materials science , differential scanning calorimetry , composite material , mesophase , extrusion , liquid crystal , annealing (glass) , eutectic system , polymer , polyester , microstructure , liquid crystalline , physics , optoelectronics , thermodynamics
Structural, Mechanical, and thermal properties of extruded sheets of a liquid crystalline copolyester containing p ‐hydroxybenzoic acid and 2‐hydroxynaphthoic acid were investigated using X‐ray diffraction measurements, differential scanning calorimetry, rheovibron measurements, and scanning electron microscopic observation. The extruded sheets of the thermotropic copolyester are composed of layered structures containing skin and core layers. A skin layer comprises fine fibrils oriented almost parallel to the extrusion direction. A core layer contains poorly oriented thicker fibrils or platelike structures. The orientation function of sheets and their tensile dynamic modulus parallel to the extrusion direction increase with increasing draw‐down ratio of the sheet. Annealing of the sheet caused the increases in the temperature and the heat of crystal—mesophase transition, the heat‐resistance to the mechanical tensiles properties, and the inherent viscosity of the polymer. The effect of annealing on the structural properties of the extruded sheet was discussed. © 1993 John Wiley & Sons, Inc.