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Band texture formation of sheared polymeric liquid crystalline state
Author(s) -
Qian Renyuan,
Chen Shouxi
Publication year - 1992
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19920530131
Subject(s) - lyotropic , liquid crystal , materials science , thermotropic crystal , polymer , texture (cosmology) , shearing (physics) , rheology , shear band , shear rate , shear (geology) , lyotropic liquid crystal , composite material , optics , crystallography , chemical physics , liquid crystalline , chemistry , image (mathematics) , optoelectronics , physics , artificial intelligence , computer science
The phenomenon of band texture formation of sheared main chain liquid crystalline polymers is reviewed. The bands seen in a polarizing microscope are optical effects. The macromolecular chains are aggregated into zig‐zag bent fibrils perpendicular to the bands. The band texture is formed during shear relaxation. The induction period depends on the shear rate applied, the shearing time, solution concentration (lyotropic), solution layer thickness, temperature and the nature of the polymer. There exists a critical shear deformation to bring a multi‐domain nematic or cholesteric phase into a monodomain continuous phase, from which the band texture is formed. These two phases show quite different rheological behavior. In certain cases randomly oriented regions of bands can also be formed during quenching of a thermotropic nematic polymer melt or during standing of a lyotropic nematic polymer solution, where the nematic domains in the melt or in the solution have grown to a sufficient size.