Polypropylene is one of the commercially most important polymers and is produced via coordinative polymerization with supported metal-organic catalysts in different processes. While kinetic measurements for slurry and gas-phase polymerization of propene are well-established, for bulk phase polymerization of propene, often the only kinetic information obtained from an experiment is the yield. In this paper, two calorimetric methods and their application for measurement of kinetics of bulk phase polymerization of propene are discussed. On the one hand a special calibration-free heat flow calorimeter and on the other hand power compensation calorimetry coupled with a software sensor for online baseline correction.

A study of the multicomponent diffusion of important processes gases in linear low density polyethylene is presented. It is demonstrated that, much like in the case of multicomponent solubilities, one cannot use pure component diffusivities to predict mass transfer rates in multicomponent systems. It is postulated that interaction between the penetrant species and the polymer modifies the free volume in a concentration-dependent manner, so it is necessary to consider the gas phase composition when calculating realistic diffusion coefficients. In addition, describing the particle morphology as an assembly of normally distributed characteristic length scales is proposed. This allows one to better fit the experimental data, and is a coherent description of experimentally observed particle morphology.

Dedicated to Prof. Timothy McKenna on the occasion of his 60th birthdayThis article outlines a kinetic study of two different Ziegler-Natta type catalysts in multistep bulk-/gas-phase polymerization of propene in a reaction calorimeter. In the first stage, bulk-phase polymerization of propene, the matrix material is produced and kinetic information about the polymerization is extracted from power compensation calorimetry data. Focus is set on the influence of hydrogen on polymerization kinetics and comparing the performance of the two catalysts. In the 2nd stage, gas-phase copolymerization of propene and ethylene, an elastomeric copolymer is produced as impact modifier and kinetic information is obtained from semibatch operation in constant conditions. The influence of monomer/comonomer ratio on copolymerization behavior of the two catalysts is investigated and compared.