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Effect of flow history on the morphology of thermotropic liquid crystalline copolyesters
Author(s) -
Joseph Eugene G.,
Wilkes Garth L.,
Baird Donald G.
Publication year - 1985
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760250702
Subject(s) - copolyester , thermotropic crystal , materials science , morphology (biology) , etching (microfabrication) , hydroxybenzoate , core (optical fiber) , isotropic etching , composite material , scanning electron microscope , polymer chemistry , chemical engineering , polyester , polymer , liquid crystalline , organic chemistry , chemistry , layer (electronics) , biology , genetics , engineering
Morphological studies have been carried out on a thermotropic liquid crystalline copolyester based on poly(ethylene terephthalate) (PET) and para hydroxybenzoate (PHB) that has been subjected to different types of flow histories. Wide angle X‐ray scattering investigations and chemical etching (n‐propylamine is the etchant) in conjunction with electron microscopy studies conducted on end gated injection molded plaques of the 60 percent PHB and 80 percent PHB copolyesters indicate that a highly oriented skin region and a less oriented core region is present. Chemical etching studies performed on microtomed layers of end gated and center gated plaques show that the etching is less pronounced in the skin region and is more pronounced in the core. The microtomed layers of the end gated injection molded plaques when analyzed by ESCA indicate the presence of a “PHB rich” skin region and a “PET” rich core region. Biaxial orientation, as denoted by WAXS measurements, is observed when the 60 percent PHB copolyester is squeezed between lubricated parallel plates.