Blow molding of mechanically recycled post-consumer rigid polyethylene packaging waste

Artikel i vetenskaplig tidskrift, 2024

Recycled post-consumer rigid polyethylene (PE) packaging waste was washed and compounded on a pilot scale using different processing conditions and the processability of recycled materials with blow molding was assessed. Compared to virgin grade high-density PE, the recycled materials showed a lower crystallinity, a lower thermo-oxidative stability, a higher ash content, a lower viscosity and melt elasticity, and a lower melt strength and drawability. The thermo-oxidative stability varied due to the different washing media. Rheological characterization by frequency-sweep measurements indicated that the virgin grade PE had as expected more linear-polymer-like characteristics whereas the recycled materials showed chain branching or crosslinking related to the processing condition during compounding. The recycled materials were successfully blow molded into 4 L-containers where they showed less resistance to flow than the virgin grade PE. The recycled materials differed in color when different washing media were used. There were no significant differences in the mechanical properties of the 4 L-containers made of virgin grade and recycled PE. Highlights: Washing, compounding, and blow molding of rigid polyethylene packaging waste were studied. The degradation varied depending on the washing and compounding conditions. Rheological results indicated chain branching or crosslinking due to degradation.