Feasibility study on the production of low melt flow rate recycled polypropylene from postconsumer waste

Abstract

AbstractPolypropylene (PP) recyclates face limitations in their use due to lower qualities compared with virgin PP, resulting from contaminations and the mixing of different PP grades. In particular, their high melt flow rate (MFR) hinders their suitability for applications requiring low MFR, such as pipes. This study investigates the feasibility of producing low MFR PP recyclates from packaging waste. For this purpose, recyclates were produced exclusively from manually sorted extrusion blow molding grades and compared with a recyclate derived from a conventional PP waste stream. Different washing temperatures and recyclate production processes were used to study their effects on the properties of the recyclates. The main objective was to determine the lowest achievable MFR and the rheological, mechanical, and thermal properties of the recyclates from improved sorting. The results are intended to serve as reference points for the evaluation of future automatic sorting trials. The enhanced sorting resulted in an 80% reduction in the MFR and improved ductility, thereby extending the potential applications of the recyclate. The different washing and production processes did not have a significant effect on the investigated properties, except for a slight decrease in the MFR with hot washing and the omission of the pelletizing step.