1.1 This International Standard specifies a method for determining the mass fraction of a polypropylene
homopolymer or copolymer which is soluble in xylene at 25 °C.
1.2 A weighed amount of dried sample is dissolved in xylene under reflux conditions, then cooled under
controlled conditions and maintained at 25 °C to ensure controlled crystallization of the insoluble fraction.
1.3 The xylene-soluble fraction is then recovered by evaporation of the xylene and determined by weighing the residue.
1.4 Other materials with solubilities similar to that of the xylene-soluble fraction, such as additives, may
interfere with the determination.