Impact of Extrusion Pre‐Treatment on Polyethylene Waste Pyrolysis

Plastic waste pyrolysis has gained increasing attention as a chemical recycling strategy, with extrusion‐based pre‐treatment emerging as a potential method to enhance process efficiency. This study systematically investigates, for the first time, the impact of extrusion pre‐treatment on the pyrolysis performance of post‐consumer high‐density polyethylene (HDPE) and linear low‐density polyethylene (LLDPE). Extrusion at 450°C for 2 min in a co‐rotating twin‐screw extruder significantly reduces the average molecular weight and alters polymer melt properties. Through controlled variations in reaction temperature (450°C and 475°C) and reaction time (15, 30, and 45 min), it is shown that extrusion pre‐treatment can significantly modify the thermal decomposition dynamics of pyrolysis, influencing reaction kinetics and product yields; however, the overall product stream composition remains relatively stable. Therefore, the present work provides valuable insights into the role of feedstock preparation in pyrolysis and highlights extrusion pre‐treatment as a key strategy for improving the efficiency and scalability of polymer waste conversion.