Renneckar showed 12% deviation of polymer in WPC by using the high resolution method [2]. The differences between Ren- neckar’s work and this work are, that on the one hand different
polymer were used Renneckar used PE and here PP-copolymer was applied and on the other hand the polymer fraction in this work contains additives like MAPP and wax, whereas Renneckar used no additives. Additionally, with the introduced method in this work fractions of polymer and wood flour can be calculated. The degradation of polymers PP and HDPE begins at 472 ◦ C respectively 517 ◦ C [13]. The step separation in TGA curve of the thermal degradation of wood flour and PE is connected with a smaller deviation because the degradation of wood flour is approximately zero during the degradation of PE polymer. It is not for PP and PP-copolymer (see Fig. 4).
Fuad et al. [16] used also thermogravimetric analysis for determination of filler content in rice husk ash and wood-based composites based on polypropylene. They showed good agreements for the component oil palm wood flour with a deviation of 5.8% between analyzed and actual filler contents by using a dynamic method (heating rate 20◦C/min, 25◦C until 550◦C, air). In Fuad’s work, the thermal degradation of used filler and polymer showed small overlapping areas. The calculation of contents in overlapping degradation areas was corrected by a coefficient. In our work, no coefficient was used because nonlinear effects are possible which means that the component ratio of the formulations influences the thermal degradation by generating different decomposition products. In this context Sharypov et al. [10] determined a nonlinear dependence between the quantity of the individual formulation components and their effect on thermal degradation of the composites.