SLOW STRESS-RELAXATION IN RANDOMLY DISORDERED NEMATIC ELASTOMERS AND GELS

Randomly disordered liquid crystalline elastomers align under stress. We study the dynamics of stress relaxation before, during, and after t he polydomain-monodomain transition. The results for different materia ls show a universal logarithmic behavior, especially pronounced in the region of the transition. The data are approximated very well by an e quation sigma(t) - sigma(eq) similar to 1/(1 + alpha ln t). We propose a theoretical model based on the cooperative mechanical resistance fo r the reorientation of each domain, attempting to follow the soft-defo rmation pathway.