2.4. Determination of the Soluble Fraction in Xylene

The results of this test provide a way to measure the relative amount of polypropylene polymers that are soluble in xylene. The xylene soluble fraction is roughly related to the amorphous portion of polypropylene. The use of xylene is preferred to determine this soluble fraction since it is more specific for detecting the atactic amount of polymers than other solvents. It has been observed that the concentration of the soluble fraction obtained through the use of the particular solvent (xylene) correlates closely with the product’s performance characteristics in specific applications, such as in the manufacture of films or fibers. In other words, the amount of soluble fraction can significantly impact how the polymer performs in different end uses.

In this investigation, the amount of fraction soluble in xylene (XS) was measured at a temperature of 25 °C using the procedure established in ISO 16152 [24].