Polymer packaging waste recycling: study of the pyrolysis of two blends via TGA

Abstract

The aim of this work is the evaluation of thermal degradation temperatures of two polymeric blends constituted by polyethylene PE, polypropylene PP, polystyrene PS and poly(ethylene terephthalate) PET through TGA in a catalytic mode. These polymers are widely known for their everyday use as packaging materials worldwide. The need for recycling is evident, the searches try to combine the energy profit with the use of common oxides as catalysts. The oxides chosen to be studied were MgO CaO, BaO γ-Al2O3 and TiO2, all dried and powdered. The results indicate that truthfully the implication of MgO lowers the decomposition peak temperature for most cases. Thus, MgO has been chosen as a satisfactory catalyst since the low acidity of the others leads to no harm for the polymers. Two blends containing the commoner polymers have also been studied in order to simulate the real conditions in solid waste, namely Blend A: PE/PET/PP of 50/25/25 and Blend B: PE/PET/PP/PS/PVC of 40/25/20/10/5 mass ratio. The most impressive result regards the PVC involvement, since small ratio in the blend reduces the decomposition beginning below 100 °C.