Abstract/Details

On the molecular anisotropy of liquid crystalline and flexible polymer systems


2004 2004

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Abstract (summary)

The demand for products of ever increasing quality or for novel applications has required increasing attention to or manipulation of the anisotropy of manufactured parts. Oriented plastics are used everywhere from recording film to automotive body parts to monofilament fishing line. Liquid crystals are also used in a wide array of applications including their dominance in the flat panel display industry, color changing temperature sensors, and woven bullet resistant fabrics. Anisotropy can also be detrimental, for instance sometimes leading to poor fracture resistance or low yield stress along specific directions.

Controlling and measuring anisotropy of materials has become increasingly important, but doing so is wrought with challenges. Measuring physical properties of isotropic liquids, such as water or most oils can be done in a straightforward fashion. Their viscosities and densities, for example, have unique values under a given set of conditions. With anisotropic fluids, like liquid crystals, the viscosity, for instance, will not only depend upon temperature, concentration, etc. but also upon the direction of observation, degree of anisotropy, source of anisotropy, and so forth. This added degree of complexity complicates our ability to define the state of the material at which the measurements are made and generally necessitates the use of more sophisticated measurement strategies or techniques.

This work presents techniques and tools for investigating anisotropy in liquid crystalline and stretched polymeric systems. Included are the use of conoscopy for the determination of birefringence and orientation of nematic liquid crystals and stretched polymers, the shear response of flow aligning nematic liquid crystal monodomains, and the design of a novel linear rheometer that allows for in situ optical or scattering investigations.

Indexing (details)


Subject
Chemical engineering;
Plastics;
Optics;
Polymers
Classification
0542: Chemical engineering
0795: Plastics
0752: Optics
0495: Polymers
Identifier / keyword
Applied sciences, Pure sciences, Anisotropy, Conoscopy, Flexible polymer, Liquid crystals
Title
On the molecular anisotropy of liquid crystalline and flexible polymer systems
Author
Van Horn, Brett L.
Number of pages
238
Publication year
2004
Degree date
2004
School code
0118
Source
DAI-B 65/01, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Advisor
Winter, H. Henning
University/institution
University of Massachusetts Amherst
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3118337
ProQuest document ID
305177721
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/305177721
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