Relaxation properties of radiation-crosslinked compositions based on poly(vinyl chloride) and oligo(oxyethylene dimethacrylates)

Using methods of mechanical and dielectric relaxation, the properties of ra diation-crosslinked compositions based on PVC and oligo(oxyethylene dimetha crylates) were studied. Both methods showed the occurrence of a single rela xation process related to the segmental mobility of chain fragments between the junctions of the three-dimensional network. As the content of oligomer in the radiation-crosslinked composition is increased, the corresponding g lass transition temperature shifts to higher temperatures and the activatio n energy of relaxation increases. This behavior is explained by the develop ment of a three-dimensional network structure which prevents molecular segm ental motion in the backbone chains of polymer matrix. In the radiation-cro sslinked compositions, the activation volume coincides by its order of magn itude with the value of the Kuhn segment in PVC.