Deformation and molecular orientation in films of metallocene polypropylene, ethylene-butylene rubber, and their 80/20 (w/w) blend revealed by the simultaneous kinetic measurement of microscopic infrared dichroism, macroscopic stress, and mesoscale strain

2005 ◽  
Vol 43 (12) ◽  
pp. 1520-1531 ◽  
Author(s):  
Yoshihito Naka ◽  
Norio Nemoto ◽  
Yihu Song
Keyword(s):  
Molecular Orientation ◽  
Kinetic Measurement ◽  
Macroscopic Stress ◽  
Infrared Dichroism

Molecular Orientation of Polyimide Films for Liquid Crystal Alignment Studied by Infrared Dichroism

1994 ◽  
Vol 33 (Part 1, No. 11) ◽  
pp. 6273-6276 ◽  
Author(s):  
Kyoko Sawa ◽  
Ken Sumiyoshi ◽  
Yoshihiko Hirai ◽  
Kazuo Tateishi ◽  
Taibun Kamejima
Keyword(s):  
Liquid Crystal ◽  
Molecular Orientation ◽  
Polyimide Films ◽  
Liquid Crystal Alignment ◽  
Crystal Alignment ◽  
Infrared Dichroism

Orientation in stretched polymer-dispersed liquid crystals

1998 ◽  
Vol 76 (11) ◽  
pp. 1642-1647 ◽  
Author(s):  
Julien Brazeau ◽  
Yanick Chénard ◽  
Yue Zhao
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Molecular Orientation ◽  
Liquid Crystalline ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed ◽  
Infrared Dichroism ◽  
Semicrystalline Matrix ◽  
Macroscopic Orientation ◽  
Strain Direction

The orientation behavior of liquid crystal molecules in stretched films of polymer-dispersed liquid crystals (PDLC) was investigated by means of infrared dichroism. The liquid crystal used is 4prime-octyl-4-biphenyl-carbonitrile (8CN); the polymer matrices are semicrystalline poly(epsilon-caprolactone) (PCL) and an amorphous miscible blend of PCL with poly(vinyl chloride) (PVC). 8CN was found to have a limit of solubility below 5 wt.% in PCL. We show that an uniaxial stretching can effectively induce a macroscopic orientation of 8CN, and that this orientation can be preserved in the films after removal of the extensional force at room temperature, where 8CN is in its liquid crystalline phase. The molecular orientation is obtained even by stretching PDLC films with 8CN in the liquid state. These results suggest that an elongated polymer cavity in stretched PDLC imposes LC director fields with respect to the long axes of the droplets, which are aligned parallel to the strain direction. The experiments also reveal that the orientation of 8CN is higher in stretched PDLC with a semicrystalline matrix (PCL) than with an amorphous matrix (the PCL-PVC blend), and that the sizes of the LC droplets also have a slight effect on the induced orientation. This work represents a first step in the exploration of new electrooptical effects of PDLC through the presence of a uniform orientation of the liquid crystal molecules and modifications of the polymer cavity at the electrical field-off state.Key words: polymer-dispersed liquid crystals, molecular orientation, infrared dichroism, electrooptical materials.

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