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Studies on fiber formation of thermotropic copolyesters
Author(s) -
Mehta Sanjay,
Deopura B. L.
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.1993.070470513
Subject(s) - thermotropic crystal , mesophase , materials science , extrusion , scanning electron microscope , liquid crystal , composite material , fiber , birefringence , polymer , polarized light microscopy , optical microscope , rheology , synthetic fiber , polymer chemistry , chemical engineering , liquid crystalline , optics , physics , optoelectronics , engineering
Thermotropic copolyesters PET/60 PHB and PET/80 PHB fibers are melt spun at different extrusion temperatures and at different draw‐down ratios. The flow behavior of PET/60 PHB is studied at different temperatures and shear rates. The melt of (PET/60 PHB) at temperatures above 265°C exhibit low viscosity and low activation energy of flow. The modulus and strength for both PET/60 PHB and PET/80 PHB fibers increase with the increase in extrusion temperature and draw‐down ratio in the ranges studied. High birefringence, indicating the presence of mesophase is observed between 265 and 300°C on a hot stage polarizing microscope. X‐ray diffraction patterns show that the molecular orientation increased with increasing draw‐down ratio. Scanning electron microscopy of these fibers shows a well‐developed highly oriented fibrillar structure. Superior mechanical performance of fibers spun at around 275°C are attributed to the presence of nematic mesophase in the polymer melt. © 1993 John Wiley & Sons, Inc.