ORIENTATION RELAXATION OF LINEAR-CHAINS ENCLOSED IN A NETWORK STUDIEDBY BIREFRINGENCE MEASUREMENTS

The relaxation of linear poly(styrene sulfonate) chains in a swollen p oly(acrylamide) network is investigated by birefringence measurements. After a stepwise deformation of the network relaxation occurs, becaus e the linear chains are initially deformed as well, but diffuse into a n isotropic conformation via the reptation mechanism. The course of th e birefringence with time agrees essentially with what follows from th e reptation model. It could be shown that the relaxation time varies a pproximately with the third power of the molar mass of the enclosed mo lecules when networks of sufficiently high network density are used. O n the other hand, the dependence of the relaxation time on network den sity or degree of swelling, respectively, seems to be much stronger th an what is expected from theory.