Propriedades reológicas e magnéticas de liomesofases colestéricas uni e biaxiais / Rheological and magnetic properties of uni and biaxial cholesteric liomesophases

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

In this work, several techniques were used to study mesophases constituted by potassium laurate, decylammonium chloride, water and brucine sulfate. This system was chosen for presenting a cholesteric biaxial phase, whose characterization continues to be worthy of investigation. Rheological measurements were made on nematic and cholesteric systems, in different compositions and situations. The values of apparent viscosity were calculated and the behaviour was characterized. For the RMN studies, a probe moIecule, the racemic form of dl alanine, was introduced in the sampIes trying to verify difference between in interaction of the enantiomers d and I with the main cholesteric matrix. The spectra were obtained with temperature variation. It was compared the data of variation of the order parameter, obtained from the direct couplings, with the half width of the wide line of the proton spectra, to obtain information about the behaviour of the alanine and of the cholesteric micelles. All the phases were accompanied by microscopy studies under polarized light, simple and efficient technique to characterize types of liquid crystal phases.

ASSUNTO(S)

reologia cristal líquido transição de fase cholesteric phase transition propriedades magnéticas magnetic properties rheology colestérico liquid crystal

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