New method for online observation of growing polyolefin particles

In classical experimental research work on catalytic olefin polymerization, kinetics and powder properties are always determined as an average value o ver a large number of polymer particles. When studying the properties of th e polymer, the powder has to be evacuated from the reactor system. This eva cuation step will often change the properties to be measured. Here, a method for direct observation of growing polymer particles is shown . To allow individual observation of a number of growing polymer particles in a catalytic gas phase polymerization, a polymerization cell was built wi th a transparent lid. The cell was placed in a microscopic video system in such a way that the particles could be observed during reaction and picture s of the particles were stored with a preset time interval. Using a 4(th) generation Ziegler-Natta catalyst at 40 degreesC and a propyl ene pressure of 8 bar, polymerizations were carried out in the presence of hydrogen. It was shown that reaction kinetics can be derived from these exp eriments, not only average values for larger number of particles, but also kinetics for individual particles. It is shown that kinetic results can be obtained in a reproducible way, and thus it is well possible to kinetically characterize a catalyst in gas phase polymerization using this method. As the current lid is not only transparent to visible light, but also to in frared light, an infrared camera can be applied to measure surface temperat ures of the growing polymer particles. This can be of large help in develop ment of single particle models. One can also think about different applicat ions and extensions. New analysis method could be applied to the same princ iple, for example Raman spectroscopy or X-ray tomography. Next to that, cur rently a stirrer is being implemented to introduce convective cooling of th e particles and one can also think about application of other media than ga s phase, like the slurry phase.