Reichert and Korte [6] used DSC measurements and showed that on the basis of the peak area of the melting point, quantification of the polymer fraction is possible. However, DSC cannot be used for quantification of the polymer if a polymer and additives with similar melting points are used in WPC. Jeske et al. [8] reported that a specific calibration test series for each polymer in WPC is necessary for DSC. Renneckar et al. [2] developed a method for the quantitative determination of WPC by using the derivative curve of the TGA curve (DTG).