Rheological Properties and Associated Structural Characteristics of some Aromatic Polycondensates Including Liquid-Crystalline Polyesters and Cellulose Derivatives

2016 ◽  
Author(s):  
J. L. White ◽  
L. Dong ◽  
P. Han ◽  
H. M. Laun
Keyword(s):  
Rheological Properties ◽  
Liquid Crystalline ◽  
Structural Characteristics ◽  
Cellulose Derivatives

Rheological properties and associated structural characteristics of some aromatic polycondensates including liquid-crystalline polyesters and cellulose derivatives (IUPAC Technical Report)

2004 ◽  
Vol 76 (11) ◽  
pp. 2027-2049 ◽  
Author(s):  
J. L. White ◽  
L. Dong ◽  
P. Han ◽  
H. M. Laun
Keyword(s):  
Shear Flow ◽  
Rheological Properties ◽  
Liquid Crystalline ◽  
Structural Characteristics ◽  
Cellulose Derivatives ◽  
Extrudate Swell ◽  
Polymer Liquid Crystals ◽  
Uniaxial Orientation ◽  
Technical Report ◽  
Thermotropic Polymer

A comparative experimental study of shear-flow rheological properties of thermotropic polymer liquid crystals by eight different laboratories is described. The materials involved four different liquid-crystalline polyesters (LCPs), a glass- fiber-filled liquid-crystalline polyester,hydroxypropyl cellulose (HPC), and two non-liquid-crystalline high-temperature polymers, a poly(etheretherketone) (PEEK), and a polyarylate (PAR). Studies were made in both steady shear-flow and dynamic oscillatory experiments. The data from the various laboratories involved were compared. The level of agreement in the data was much less for most liquid-crystalline polymers than for similar isotropic melts. The Cox –Merz rule is valid for PEEK and PAR, but not for the LCPs and HPC. The occurrence of low levels of extrudate swell and high levels of uniaxial orientation in extrudates of the LCPs and HPC is described.

Rheological Properties of Liquid Crystalline Solutions of Cellulose Derivatives

2021 ◽  
Vol 63 (4) ◽  
pp. 363-368
Author(s):  
S. A. Vshivkov ◽  
E. V. Rusinova ◽  
A. S. Abo Saleh
Keyword(s):  
Rheological Properties ◽  
Liquid Crystalline ◽  
Cellulose Derivatives

Use of light microscopy in the qualitative and quantitative study of liquid crystalline order

1992 ◽  
Vol 50 (1) ◽  
pp. 264-265
Author(s):  
Christopher Viney
Keyword(s):  
Light Microscopy ◽  
Liquid Crystalline ◽  
Structural Characteristics ◽  
Molecular Order ◽  
Liquid Crystalline Phases ◽  
Convenient Technique ◽  
Liquid Crystalline Materials ◽  
Transparent Windows

Light microscopy is a convenient technique for characterizing molecular order in fluid liquid crystalline materials. Microstructures can usually be observed under the actual conditions that promote the formation of liquid crystalline phases, whether or not a solvent is required, and at temperatures that can range from the boiling point of nitrogen to 600°C. It is relatively easy to produce specimens that are sufficiently thin and flat, simply by confining a droplet between glass cover slides. Specimens do not need to be conducting, and they do not have to be maintained in a vacuum. Drybox or other controlled environmental conditions can be maintained in a sealed chamber equipped with transparent windows; some heating/ freezing stages can be used for this purpose. It is relatively easy to construct a modified stage so that the generation and relaxation of global molecular order can be observed while specimens are being sheared, simulating flow conditions that exist during processing. Also, light only rarely affects the chemical composition or molecular weight distribution of the sample. Because little or no processing is required after collecting the sample, one can be confident that biologically derived materials will reveal many of their in vivo structural characteristics, even though microscopy is performed in vitro.

Preparation, characterization and novel photoregulated rheological properties of azobenzene functionalized cellulose derivatives and their α-CD complexes

Polymer ◽  
2004 ◽  
Vol 45 (18) ◽  
pp. 6219-6225 ◽  
Author(s):  
X. Hu ◽  
P.J. Zheng ◽  
X.Y. Zhao ◽  
L. Li ◽  
K.C. Tam ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Cellulose Derivatives
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