Soft elasticity and mechanical damping in liquid crystalline elastomers

The dynamic soft response of polydomain liquid crystalline elastomers to si mple shear is reported. Significantly, these materials also show extremely large loss behavior with tan delta exceeding 1 or even 1.5 over very wide t emperature ranges, with clear implications for damping applications. By com paring materials that exhibit different types of liquid crystalline phases, we identify the nematic state as a better damping phase than that in mater ials with smectic phases. Additionally, we provide experimental evidence fo r directions which should be explored for further improvements in the dampi ng behavior of liquid crystalline elastomers. (C) 2001 American Institute o f Physics.