Estimation of morphology characteristics of porous poly(propylene) particles from degassing measurements

The transport of reaction species in polyolefin particles affects both the polymerization and the degassing of the powder in the down-stream processing. The morphology of particles-that is, the distribution of polymer and pore phases-predetermines their degassing behavior. We utilize gravimetric measurements to obtain the dynamics of degassing and to determine morphology characteristics of porous poly(propylene) particles. We found that Fick's diffusion model is not generally capable of fitting the shape of degassing curves of porous particles. Therefore we propose a particle model including two sizes of compact polymer granules and demonstrate that the degassing can be descried by this model and that the model is capable of estimating fractions of large and small compact zones and the size of large compact zones.