INVESTIGADORES
GARAY Raul Oscar
artículos
Título:
Synthesis and Characterization of Extended-rod Thermotropic Polyesters with Polyoxyethylene Pendant Sustituents
Autor/es:
LENZ, R. W.; FURUKAWA, A.; BHOWMIK, P. K.; GARAY; R. O.; MAJNUSZ, J.
Revista:
POLYMER
Editorial:
ELSEVIER SCI LTD
Referencias:
Lugar: Amsterdam; Año: 1991 vol. 32 p. 1703 - 1712
ISSN:
0032-3861
Resumen:
The liquid crystalline properties of a series of aromatic polyesters
prepared from alkoxy and alkoxyethyleneoxy-substituted hydroquinone
monomers and either terephthaloyl chloride or diphenyl terephthalate
were studied by optical and thermal methods. The melting temperatures of
these polymers were considerably less than the corresponding polymers
with n-alkyl substituents with the same number of atoms in the
pendant substituent group on the hydroquinone ring. The melting
temperature decreased in an exponential manner with the increase in the
number of atoms in the alkoxy substituents, and at some temperature
above their melting transition, a transition from a highly threaded
liquid crystalline texture to a highly birefringent schlieren liquid
crystalline texture was observed to occur for all polymers. All polymers
except one were also observed to become homeotropic at elevated
temperatures. When cooled from the homeotropic melts, a nematic glass
was observed to form for the majority of polymers. Two polymers, on
cooling from homeotropic melts to room temperature, showed optical
textures representative of Williams domains which formed without the
application of any electrical field.