Crystallization Analysis Fractionation (CRYSTAF) 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, the separation and analysis are performed in a single temperature ramp (crystallization cycle). The sample is placed in a vessel where dissolution and precipitation take place.
The temperature is increased to fully dissolve the polymer in either 1,2,4-Trichlorobenzene (TCB) or Orto-Dichlorobenzene (oDCB). As the system begins to lower the temperature at a controlled rate (until reaching 30ºC), and the polymer begins to precipitate, an aliquote is taken at each step and the concentration is measured by the infrared detector (IR4). The concentration data obtained across the sampling correspond to the cumulative curve of the chemical composition distribution.
