Re-stabilization of recycled polymers

During recycling operations in molten state, polymers can undergo drastic d egradation phenomena due to the thermomechanical stress acting on the melt. Rheological and mechanical properties change deeply and the secondary mate rials show scarce processability and poor properties. Restabilization is th erefore a necessary step to avoid the dangerous effects of these phenomena. In this work the properties of polypropylene and polyvinylchloride reproce ssed in presence of different stabilizing agents are reported. When the sta bilizer is added before each reprocessing step the molecular weight changes only slightly with the melt operation and the properties remain very simil ar to those of the virgin polymer.