PRINCIPLES OF SOLID-PHASE GRAFTING ONTO P OLYPROPYLENE - DIFFUSION AND SORPTION OF GRAFTING AGENTS IN THE PP GRANULES

In solid-phase grafting of polymers, diffusion and equilibrium sorptio n play a key role in determining the local concentration of monomers i n polymer particles. In the present work, equilibrium sorption and dif fusion for different monomers in polypropylene particles were investig ated. The combination of kinetic and thermodynamic measurements with a progressive thermodynamic modelling was proved to be successful; i.e. the assumptions and requirements of modelling are acceptable. The res ults are used to explain the overall process. It is shown that the des cription of the diffusion-rate with only one parameter is sufficient. A separation of mass transfer into contributions due to pore-diffusion and to solid-phase diffusion (amorphous regions) is not necessary.