Transport and reaction in reconstructed porous polypropylene particles: Model validation

We attempt to validate tomography-based spatially 3D model of polypropylene particle by comparison of model predictions with measured degassing characteristics of polypropylene powder samples. Statistically relevant number of porous PP particles from three particle size fractions is inspected by X-ray micro-tomography. The voxel size of reconstructed porous PP particles is between 1 and 5 μm. We show that closed porosity occurring in reconstructed particles has a negligible effect on the dynamics of particle degassing. It was found that the voxel size smaller than 3 μm is required for a good agreement between model predictions and experimental data. We demonstrate that tomography-based model is capable to address the problem of mass transport limitation during polymerization reaction in real particle structure. Two statistical descriptors suitable for the characterization of compact zones of polymers occurring in polypropylene particles are introduced.