CRYSTAF (Crystallization Analysis Fractionation) is a technique used to measure the Chemical Composition Distribution (CCD) in polyolefins based on the segregation of crystals of different morphology or comonomer content by crystallizability. In this technique, separation and analysis are performed in a single step; the crystallization cycle, where the polymer solution is sampled and its concentration is analyzed at the same time that the temperature is decreasing for the crystallization by using an infrared detector (IR4).  Concentration data obtained at each temperature sampled correspond to the cumulative curve of the CCD.