OZONE RESISTANCE, RELAXATION PROPERTIES, AND MOLECULAR MOBILITY OF BUTADIENE STYRENE THERMOPLASTIC ELASTOMERS

The kinetics of mechanical stress relaxation in a series of thermoplas tic elastomers based on diblock copolymers of butadiene and styrene wa s studied in the temperature interval of 280 - 353 K. The molecular dy namics and structure of polymer surface were investigated by ESR spin probe technique and IR ATR spectroscopy. It was found that in inert en vironment the stress relaxation is determined by many factors and we f ailed to establish any correlation between parameters considered. In o zone-air environment, the rate of stress relaxation correlates with th e frequency of spin probe rotation. This indicates that in in aggressi ve environment the kinetics of stress relaxation is governed by the ve locity of the crack growth, which in its turn is determined by the dyn amics of molecular motion, because the latter is responsible for the r ate of microscopic stress relaxation in the crack tip.