Einfluss von verarbeitungsbedingungen und additiven auf die abbaureaktionen von SIS‐blockcopolymeren

SIS block copolymers are used particularly as polymer component in hot melt adhesives. During compounding at temperatures of 170–180°C undesired viscosity decrease occurs occasionally. For that reason the influence of additives and the role of compounding conditions, particularly the oxygen concentration, on the degradation of SIS has been investigated. It was found that primary antioxidants are unable to reduce the degradation of SIS under anaerobic or oxygen deficient conditions, but they are very effective when excess of oxygen is present in the system (e.g. an open mixer or mill). C-radical scavengers reduce the chain scission reaction at high oxygen concentrations, too, but accelerate the decrease of the molecular weight under inert gas atmosphere.