4. Control and designation

4.1 Characterization and control methods

• Measurement of structural parameters and rheological properties

The structural parameters of PP can be measured by various methods:

• the molar masses in number and mass and their I _p ratio are measured by gel permeation chromatography;

• the isotacticity rate is equal to the mass fraction of PP insoluble in boiling n-heptane;

• the degree of crystallinity is assessed by differential scanning calorimetry (DSC), density measurement or X-ray measurement.

Melt rheological properties are characterized...