Halato-telechelic polymers. VII. Viscoelastic behavior of α,ω-divalent cation dicarboxylato polybutadiene

TLDR: In this article, a secondary relaxation characteristic of ionic aggregates obeys an Arrhenius type of activation, the energy of which is in inverse proportion to the ionic radius of the cation.

Abstract: Ba, Ca, Mg, and Zn short-length carboxylato-telechelic polybutadienes (Mn = 4,600) exhibit thermorheological simplicity. A secondary relaxation characteristic of ionic aggregates obeys an Arrhenius type of activation, the energy of which is in inverse proportion to the ionic radius of the cation, whereas the mean size of the ionic aggregates is proportional to it. The glass transition of the carboxy-telechelic polybutadiene is quite independent of the degree of neutralization and of the subsequent phase separation by the metal cations. The increase in cation size favors the growth of the multiplets into layered structures. Two sets of relaxation times are reported for the smallest alkaline-earth cation (Be). They suggest the existence of small multiplets unable to grow except into clusters.