Slow stress relaxation in liquid crystal elastomers and gels

Randomly disordered (polydomain) liquid crystalline elastomers align under stress above the structural glass transition T-g to form a monodomain. We s tudy the dynamics of stress relaxation during the polydomain-monodomain (P- M) transition analysing the results using the spin-glass nematic order conc ept. The results for different materials show a universal ultra-slow logari thmic behaviour, especially pronounced in the region of the P-M transition. The data are approximated very well by an equation sigma(t) similar to sig ma(eq)(epsilon) + A/(1 + alpha ln t). We propose a theoretical model of sel f-retardation based on the concept of cooperative mechanical resistance for the re-orientation of each domain, attempting to follow the soft-deformati on pathway.