Ricerc@Sapienza

The thermal behavior and pyrolytic kinetic analysis of main waste polymers (polypropylene (PP), polyethylene
film (PE), poly(ethylene terephthalate) (PET), polystyrene (PS)) and three synthetic mixtures representing commingled postconsumer
plastics wastes (CPCPWs) output from material recovery facilities were studied. Thermogravimetry (TG) pyrolysis
experiments revealed that the thermal degradation of single polymers and the synthetic mixture enriched in PP occurred in
one single step. The other two mixtures underwent a two-consecutive, partially overlapping degradation steps, whose peaks
related to the first-order derivative of TG were deconvoluted into two distinct processes. Further TG experiments carried
out on binary mixtures (PS/PP, PET/PP, PET/PEfilm and PP/PEfilm) showed a thermal degradation reliance on composition,
structure and temperatures of single polymer components. A kinetic analysis was made for each step using the Kissinger-
Akahira-Sunose (KAS) method, thus determining almost constant activation energy (Ea) for pyrolysis of PS, PET, PP and
PE film in the range 0.25 step of CPCPW2 and CPCPW3, both ascribable to degradation of PP and PE film. To account for the reliability of these
values the integral isoconversional modified method developed by Vyazovkin was also applied.