A new model to pyrolysis capacity quantification using thermogravimetric data for polymers reprocessed

Abstract

Formulation of a new mathematical model, through the dimensional analysis methodology, to quantify the pyrolysis capacity of organic materials and thermoplastic polymers by means of the pyrolysis index is presented. The importance of this index is that it is possible to quantify the capacity of the polymer post-consumption or recycling to be pyrolyzed to obtain useful fuel fractions in the actual society. The new model is compared with three models of the literature, using non-isothermal (dynamic) thermogravimetric analysis data for the raw and reprocessed Polystyrene case study. This polymer is reprocessed five times in a single screw extruder. The raw and reprocessed polymer were characterized by proximate, elemental analysis and dynamic thermogravimetry under nitrogen atmosphere at four heating rates. A non-dimensional correlation was obtained to calculate the pyrolysis index as a function of the heating rate, characteristic temperatures, and conversion. It was found that the pyrolysis capacity increases with the heating rate and number of reprocessing in extrusion. In addition, the new model better fits the data to a linear trend between pyrolysis index with the heating rate and number of reprocessing.