Thermal decomposition of polypropylene in the presence of wood-derived materials

Thermal decomposition of polypropylene (PP) was studied in the presence of wood flour, lignin, cellulose and charcoal in order to understand the pyrolytic behavior of the mixture of these components occurring in waste. Thermogravimetry/mass spectrometry was applied for monitoring the weight loss and the product evolution profiles under slow heating conditions. The formation of oligomeric products was analyzed by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Since the charring reactions of wood are still proceeding during the PP decomposition, the interactions between PP and char devolatilization are expected to be rather pronounced. The effect of the freshly formed pyrolytic chars on the decomposition of PP was simulated by mixing PP with pure activated charcoal. Activated charcoal had the most significant effect on the decomposition profile and the product distribution of polypropylene. In the presence of charcoal the decomposition shifted to lower temperature and the DTG curve became broader. The presence of charcoal promotes the formation of monomer and dimer. The effect of wood flour, lignin and cellulose is less pronounced. Though the decomposition starts at lower temperature in the presence of these additives and the DTG curve became broader, the temperature of the maximum decomposition rate and the char yields did not change significantly. (C) 2000 Elsevier Science B.V. All rights reserved.