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Anomalous viscoelastic response of nematic elastomers
S M Clarke1, A R Tajbakhsh, E M Terentjev
1Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom.
Physical Review Letters
|May 1, 2001
Summary
We studied nematic elastomers and found that their mechanical properties change significantly with deformation. This behavior is linked to the director
Area of Science:
- Materials Science
- Polymer Physics
- Rheology
Background:
- Nematic elastomers are advanced materials exhibiting unique mechanical and optical properties.
- Understanding their viscoelastic response is crucial for developing novel applications.
- The interplay between director dynamics and mechanical deformation is not fully understood.
Purpose of the Study:
- To investigate the linear viscoelastic response of oriented monodomain nematic elastomers.
- To theoretically model and experimentally validate the influence of director dynamics on mechanical properties.
- To identify the relationship between shear geometry, nematic order, and viscoelastic behavior.
Main Methods:
- Development of a theoretical model incorporating director relaxation dynamics.
- Combined theoretical analysis and experimental dynamic mechanical measurements.
- Utilized oriented monodomain nematic elastomer samples.
Main Results:
- The theoretical model predicted a significant decrease in dynamic modulus under specific deformation conditions.
- Experimental results confirmed the model's predictions, showing dependence on shear geometry and nematic order.
- A substantial mechanical loss was observed, directly attributed to director relaxation.
Conclusions:
- Director relaxation dynamics play a critical role in the viscoelastic response of nematic elastomers.
- The study provides a framework for predicting and controlling the mechanical behavior of these materials.
- Findings offer insights for designing nematic elastomers with tailored viscoelastic properties.