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Extrusion, fiber formation, and characterization of thermotropic liquid crystalline copolyesters
Author(s) -
Wang Yong,
Wu Dacheng
Publication year - 1997
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/(sici)1097-4628(19971114)66:7<1389::aid-app17>3.0.co;2-y
Subject(s) - materials science , thermotropic crystal , composite material , copolyester , mesophase , scanning electron microscope , fiber , extrusion , rheology , melt spinning , ultimate tensile strength , viscosity , shear thinning , shear rate , birefringence , liquid crystal , polyester , polymer , liquid crystalline , physics , optoelectronics , quantum mechanics
The flow behavior and the effect of the spinning conditions on the fiber properties and structure of the copolyesters, i.e., samples of copoly( p ‐hydroxybenzoate‐bisphenol A terephthalate), were investigated. The experimental results indicated that the apparent viscosity was affected significantly by shear rate, melt temperature, and p ‐hydroxybenzoate unit content; and the copolyester melts exhibit highly shear thinning behavior. The fiber modulus increase with the increase in extrusion temperature and draw‐down ratio, and the tensile properties could be improved when a high spin draw ratio was used. High birefringence, indicating the presence of mesophase, was observed on a hot‐stage polarizing microscope. Scanning electron microscopy revealed that the fibers spun at relatively high temperature had a well‐developed, highly oriented fibrillar structure. The fibers spun at low temperatures, however, were poorly oriented and nonfibrillar in character. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1389–1397, 1997