Ziegler-Natta catalyst sonofragmentation for controlling size and size distribution of the produced polymer particles

The size of the Ziegler-Natta catalyst (ZNC) particles can have a strong impact on their activity and the size and size distribution (SD) of the final polymer particles. In this work, we apply sonofragmentation to break the ZNC particles dispersed in hexane. Our main goals are first to monitor the breakage induced by the ultrasonic power to understand the kinetics and the effect of sonofragmentation on the colloidal stability of the ZNC particles. Second, we explore the effect of sonofragmentation on the polymerization performance of the ZNC particles. It is found that sonofragmentation can not only reduce the size but also narrow the SD of the ZNC particles. From the tests of ethylene polymerization, we observed that the catalyst yield of the sonofragmentation-treated ZNC is substantially higher than that of the untreated one and that the obtained polymer particles exhibit a smaller average size and a narrower SD.