A Method of Avoiding the Edge Current Divergence in Perturbation Loss Calculations (Short Paper)
From a consideration of the properties near the edge of a flat finite-thickness strip and an elliptic cross-section strip, it is shown that the divergence that arises in the perturbation method near a sharp edge can be handled by halting the loss calculation at a definite distance just short of the strip edge. This distance can be expressed in terms of the radius of curvature at the tip for a rounded edge, and in terms of the strip thickness for a flat edge.
The diffusion resistance to monomers during heterogeneous polymerization of polyolefin particles may have a significant effect on the observed activity. This diffusivity is, in general, unknown. To gain more information on this diffusion resistance in such systems, PFG-NMR has been used to measure the diffusion of organic solvents in various systems of porous polymer particles. In such systems the complex morphology and geometry demands careful analysis of the PFG-NMR attenuation curve. In this study, effects from restricted diffusion, domains having different diffusivity, and internal magnetic field gradients are expected. Thus, the obtained diffusivities have to be considered carefully, and a way to analyze the data taking these effects into account is presented. Copyright 2001 Academic Press.