The relaxation spectra of polymer networks with different types of topology, ordering, heterogeneity

Abstract

Many characteristic features of the relaxation spectra of the different types of polymer networks (meshlike and tree-like) manifesting in experimental behaviour are determined by manifold types of local and long-range irregularities or inclusions existing even in the simplest network structures. These irregularities in the local topology, in the fluctuations of the local orientational order existing due to stretching of the chains in the bulk elastomers (even in the non-ordered elastomers), also due to possible LC-ordering, the distribution of chain lengths between junctions and possible existence of cross-link agglomerations and domains at random cross-linking and the influence of the position of the chain element relative to junctions lead to variety of relaxation spectra, frequency and time-dependencies. The long-range hydrodynamic effects in bulk network can also lead to drastic variation of relaxation spectra. The inclusion of elongated rigid particles in polymer gels and network leads to the appearance of new branches of relaxation spectra changing and overlapping the relaxation spectra of the primary network system.