Electric-Field-Induced Segmental Reorientation in Ferroelectric Liquid Crystalline Polymers and Elastomers

1999 ◽  
Vol 32 (5) ◽  
pp. 1570-1575 ◽  
Author(s):  
S. Shilov ◽  
E. Gebhard ◽  
H. Skupin ◽  
R. Zentel ◽  
F. Kremer
Keyword(s):  
Electric Field ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Crystalline Polymers

Side chain liquid crystalline polymers: Electric field effects and nonlinear properties

1995 ◽  
Vol 96 (1) ◽  
pp. 185-206 ◽  
Author(s):  
Dominique Gonin ◽  
Bertrand Guichard ◽  
Claudine Noël ◽  
François Kajzar
Keyword(s):  
Electric Field ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Side Chain ◽  
Electric Field Effects ◽  
Crystalline Polymers ◽  
Nonlinear Properties ◽  
Field Effects

ELECTRORHEOLOGICAL NORMAL STRESS MEASUREMENTS OF POLYMER SOLUTIONS AND SUSPENSIONS

1996 ◽  
Vol 10 (23n24) ◽  
pp. 3237-3242 ◽  
Author(s):  
KEIJI MINAGAWA ◽  
HIROSHI KIMURA ◽  
JUN-ICHI TAKIMOTO ◽  
KIYOHITO KOYAMA
Keyword(s):  
Electric Field ◽  
Normal Stress ◽  
Liquid Crystalline ◽  
Stress Measurement ◽  
Liquid Crystalline Polymers ◽  
Polymer Chains ◽  
Low Molecular Weight ◽  
Elastic Network ◽  
Crystalline Polymers ◽  
Additional Information

Normal stress measurement under an electric field is demonstrated as a new method of evaluating ER effects. The measurement was applied to liquid crystalline polymers, low molecular-weight liquid crystals, polymer suspension, and aluminum suspension. The normal stress of the liquid crystalline polymers drastically increased under an electric field at high shear rate, which suggests existence of an elastic network structure of the polymer chains. The normal stress of the suspensions also changed in the field, indicating that interaction of particles results in an increase of both shear stress and normal stress. These changes of the normal stress give additional information which is helpful for characterizing ER effects.

ELECTRORHEOLOGICAL EFFECT OF LIQUID CRYSTALLINE POLYMERS

1996 ◽  
Vol 10 (23n24) ◽  
pp. 3191-3200 ◽  
Author(s):  
AKIO INOUE ◽  
SYUNJI MANIWA ◽  
YOICHIROH IDE ◽  
HIROJI ODA
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Side Chain ◽  
Shear Stresses ◽  
Spacer Length ◽  
Crystalline Polymers ◽  
Electrorheological Effect ◽  
Base Polymer

A series of side chain liquid crystalline polymers (LCPs) containing different spacer length and various terminal structures has been prepared and their electrorheological (ER) effect has been investigated. Although the LCP itself showed small ER effect, a mixture of the LCP with a plain polydimethylsiloxane (PDMS) oil was found to show a large increase in shear stress upon application of an electric field. The shear stresses under DC 2 kV/mm of an electric field were 14 to 4 times those without the application of an electric field over the temperature range of 30 to 160 °C for a 2:1 mixture (by weight) of a LCP containing an oxyethylene spacer and a mesogen based on 4-cyanophenyl benzoate with PDMS. Two mechanisms responsible for the generation of the ER effect was suggested from the investigation using phenyl-substituted PDMS and an analysis by DSC: oriented LC network induction, and phase separation between the LC base polymer and PDMS.

Structure-property relations of liquid crystalline polymers

1987 ◽  
Vol 45 ◽  
pp. 460-463
Author(s):  
Linda C. Sawyer
Keyword(s):  
Solid State ◽  
Liquid Crystalline ◽  
Structural Model ◽  
Crystalline Polymer ◽  
Liquid Crystalline Polymers ◽  
Mechanical Anisotropy ◽  
Structure Property ◽  
Preparation Methods ◽  
Crystalline Polymers ◽  
Extended Chain

Recent liquid crystalline polymer (LCP) research has sought to define structure-property relationships of these complex new materials. The two major types of LCPs, thermotropic and lyotropic LCPs, both exhibit effects of process history on the microstructure frozen into the solid state. The high mechanical anisotropy of the molecules favors formation of complex structures. Microscopy has been used to develop an understanding of these microstructures and to describe them in a fundamental structural model. Preparation methods used include microtomy, etching, fracture and sonication for study by optical and electron microscopy techniques, which have been described for polymers. The model accounts for the macrostructures and microstructures observed in highly oriented fibers and films.Rod-like liquid crystalline polymers produce oriented materials because they have extended chain structures in the solid state. These polymers have found application as high modulus fibers and films with unique properties due to the formation of ordered solutions (lyotropic) or melts (thermotropic) which transform easily into highly oriented, extended chain structures in the solid state.

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