Dynamic mechanical relaxations and microhardness indentations of styrene–ethylene copolymers obtained with heterogeneous catalysts

The dynamic-mechanical behaviour of several copolymers of ethylene and styrene, obtained with a heterogeneous catalyst, has been analysed and compared with that of the corresponding homopolymers. The copolymers show three relaxations α, β and γ. The α relaxation is associated with the crystalline content, the γ relaxation with the movement of methylene groups in the main chain and the β relaxation seems to be associated with the interfacial content. The α and β relaxations overlap and their intensity depends on the styrene content. All the copolymer samples and their fractions, either soluble or insoluble in boiling toluene, show the β relaxation at about −10°C, indicating that they do not have a complete block structure. The microhardness values of the polymers studied have been related to the composition of the copolymers and the crystallinity of the samples.