Interpretation of the “melt strength” test

The “melt strength” test for molten polymers is shown to be a function of several rheological parameters. Interpretation of results in terms of extensional viscosity differences is consequently not straightforward, if possible at all.     

The role of pore structure in the catalytic behavior of “unaged” and “aged” silica-alumina catalysts

This is a review of research concerning the role played by the porous structure of silica-alumina catalysts on the evolution of organic catalytic processes. A strong effect of the geometrical shape of the pores on catalytic activity and selectivity has been evidenced. The experimental results have also been interpreted by means of a simplified mathematical model, able to relate selectivity for a reaction of the type A → B → C to the geometrical features of macro-microporous catalyst pellets, or granules. The theoretical results are in qualitatively satisfactory agreement with the experimental data.