Elongational flow of a liquid crystalline polymer solution under a transverse electric field

2002 ◽  
Vol 46 (1) ◽  
pp. 1-10 ◽  
Author(s):  
I-Kuan Yang
Keyword(s):  
Electric Field ◽  
Polymer Solution ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Transverse Electric ◽  
Elongational Flow ◽  
Crystalline Polymer ◽  
Transverse Electric Field

Flow Induced Unstable Structure of Liquid Crystalline Polymer Solution in L-Shaped Slit Channels

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
Takatsune Narumi ◽  
Jun Fukada ◽  
Satoru Kiryu ◽  
Shinji Toga ◽  
Tomiichi Hasegawa
Keyword(s):  
Polymer Solution ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Flow Behavior ◽  
Crystalline Polymer ◽  
Test Fluid ◽  
Radius Of Curvature ◽  
Unstable Behavior ◽  
Corner Flow ◽  
Side Flow

An experimental study has been conducted on unstable structures induced in two-dimensional slit flows of liquid crystalline polymer solution. 50wt% aqueous solution of hydroxyl-propylcellulose (HPC) was utilized as a test fluid and its flow behavior in L-shaped slit channels with a cross section of 1mm height and 16mm width was measured optically. The inner corner of the L-shaped channel was rounded off in order to clarify the influence of the radius of curvature on the unstable behavior. A conversing curved channel was also tested. The flow patterns of the HPC solution in the channels were visualized with two crossed polarizers and we observed that typical wavy textures generated in the upstream of the corner almost disappeared after the corner flow. However, an unstable texture was developed again only from the inner corner in downstream flow. The fluctuation of the orientation angle and dichroism were also measured with a laser opto-rheometric system and it was found that the unstable behaviors of the HPC solution have periodic oscillatory characteristics at a typical frequency. In the inner side flow after the corner, the periodic motion became larger toward the downstream and then higher harmonic oscillations were superimposed. Larger rounding off of the inner corner suppressed the redevelopment of unstable behavior, and it is considered that the rapid regrowth of unstable behavior was caused by rapid deceleration at the corner flow. Moreover, the unstable structure was stabilized with an accelerated (elongated) region in the corner flow and the converging channel was helpful to obtain a stable structure in the downstream region.

Mechanism of the Occurrence of Wavy Texture in Slit Flows of a Liquid Crystalline Polymer Solution

2002 ◽  
Vol 2002.77 (0) ◽  
pp. _13-49_-_13-50_
Author(s):  
Masatada SHINDOU ◽  
Noriyasu MORI ◽  
Tsutomu TAKAHASHI ◽  
Kiyoji NAKAMURA
Keyword(s):  
Polymer Solution ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Wavy Texture

Viscosity of a liquid crystalline polymer solution with a polydomain or a band texture

1997 ◽  
Vol 36 (6) ◽  
pp. 628-631
Author(s):  
Vassilios T. Tsakalos ◽  
Edith Peuvrel-Disdier ◽  
P. Navard
Keyword(s):  
Polymer Solution ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer

Aggregation Structure and Electro—Optical Properties of (Liquid Crystalline Polymer)/(Low Molecular Weight Liquid Crystal) Composite System

1989 ◽  
Vol 171 ◽  
Author(s):  
Tisato Kajiyama ◽  
Hirotsugu Kikuchi ◽  
Akira Miyamoto ◽  
Satoru Moritomi ◽  
Jenn—Chiu Hwang
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Electric Field ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Smectic Phase ◽  
Side Chain ◽  
Low Molecular Weight ◽  
Smectic Layer

ABSTRACTA series of thin films composed of liquid crystalline polymer (LCP) and low molecular weight liquid crystal (LMWLC) was prepared by a solventcasting method or by a bar—coating method. LCPs were of mesogenic side chain type with strong or weak polar terminalgroups in the side chain portion. A mixture of smectic LCP (LCP with side chain of strong polar end) and nematic LMWLC formed a smectic phase in a LCP weight fraction range above 50 %. Also, a mixture of nematic LCP (LCP with side chain of weak polar end) and nematic LMWLC with strong polar group induced a new smectic phase in a LCP molar fraction range of 20–80 %. Reversible and bistable electro-optical effects based on light scattering were recognized for a smectic phase of a binary composite composed of LCP and LMWLC. A light scattering state caused by many fragmented smectic lamellae appeared in the case of application of an a.c. electric field below a threshold frequency (∼l Hz). Furthermore, application of a 100 Vp—p a.c. field of 1 kHz made the transmission light intensity increased to 94 % within a few seconds. The optical heterogeneity in asmectic layer composed of the side chain group of LCP was caused by the difference of twoforces based on both dielectric anisotropy of the side chain and electrohydrodynamic motion of the main chain. Since application of a low frequency electric field causes an ioniccurrent throughout the mixture film, it is reasonable to consider that an induced turbulent flow of main chains by an ionic current collapsed a fairly well organized large smectic layer into many small fragments, resulting in an increase in light scattering. The response speed of LCP upon application of an electric field increased remarkably by mixingLMWLC. In the case of a smectic mesophase, turbid and transparent states remained unchanged as it was, even though after removing an electric field.1Such abistable and reversiblelight switching driven by two different frequencies of electric field could be newly realized by both characteristics of turbulent effect of a wellorganized large smectic layer of LCP and rapid response of LMWLC. We believe that the LCP/LMWLC mixture system is promissing as a novel type of “light valve” exhibiting memory effect (bistable light switching).

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