Abstract

Critical behavior was studied with a crosslinking system obtained by living anionic polymerization, where the primary chain length was kept constant and the crosslinking density was varied. Gelation was found at a critical ratio of crosslinker per chain X~ = 0.884 ± 0.004. Different samples from the pre gel region were studied by dynamic and static light scattering in dilute solution and oscillatory rheology in melt. The exponents y=1.75 ±0.38 and v = 0.98 ± 0.19, determined from M~ and R~ dependence on (X~ X ), are in accordance with three dimensional percolation theory. The distribution of diffusion coefficients obtained by inverse Laplace transformation of the time correlation function shows power law behavior in a limited interval, from which an exponent v = 2,17 ± 0.03 is derived. Rheological measurements show a systematic change of G'(w ) and G(w from typical liquid to the critical gel behavior,

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