Rheology and Optical Properties of Thermotropic Liquid Crystalline Polymers

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Novel applications of thermotropic liquid crystalline polymers (TLCP) are currently prevented by the lack of understanding of the structure formation processes in the liquid crystalline state and during solidification (transition to the crystal state). Such understanding is required for controlling mechanical, electrical, and optical properties which not only depend on the intrinsic molecular properties but also on the large-scale texture. This research involves a cooperative study of the structuring of TLCPs in rheological and magnetic fields. Light scattering and microscopy (R.S. Stein) and rheology (H.H. Winter) will be applied to specifically synthesized samples (Polaroid) and the magnetic field of a laboratory will be utilized to create the necessary alignment. Intermediate textural states will be produced by applying well-defined mechanical and electrical fields. The study of the field induced monodomain will give the intrinsic properties (Miesowicz viscosities, Frank elastic constants) which are needed to understand the behavior of polydomains. The natural polydomain and intermediate disclination densities will be studied to lay the foundation for practical applications (design of suitable processing equipment) as well as for a theoretical description of polydomain TLCPs.