TY - JOUR

T1 - Analysis of different polypropylene waste bales

T2 - Evaluation of the source material for PP recycling

AU - Geier, Jutta

AU - Bredács, Márton

AU - Witschnigg, Andreas

AU - Vollprecht, Daniel

AU - Oreski, Gernot

N1 - Publisher Copyright: © The Author(s) 2024.

PY - 2024/2/6

Y1 - 2024/2/6

N2 - The use of the polypropylene (PP) recyclates in certain processing methods and applications is still limited by their quality. The high melt flow rate (MFR) and the inconsistent properties of recyclates are common obstacles to their use. Therefore, this work aims to identify possible reasons for the low and inconsistent quality of PP recyclates depending on the source material in PP waste bales. The levels of polymeric and non-polymeric contaminants were assessed. As mixing of different PP grades is an issue for the MFR, the proportions of the different processing grades were also investigated and the potential of sorting by processing method to produce lower MFR recyclates was assessed. The analysis showed that the waste bales, although pre-sorted, still contained high amounts of contaminants. Injection moulding was found to be the predominant processing method in the bales, explaining the high MFR of PP recyclates. However, a sufficiently high amount of low MFR products was found in the bales, which seems promising for the production of low MFR recyclates. Seasonal variations in the composition of the waste bales were identified as one of the reasons for the inconsistent qualities of recyclates. These results highlight the importance of proper sorting and treatment of PP waste bales prior to reprocessing in order to obtain high-quality recycled products.

AB - The use of the polypropylene (PP) recyclates in certain processing methods and applications is still limited by their quality. The high melt flow rate (MFR) and the inconsistent properties of recyclates are common obstacles to their use. Therefore, this work aims to identify possible reasons for the low and inconsistent quality of PP recyclates depending on the source material in PP waste bales. The levels of polymeric and non-polymeric contaminants were assessed. As mixing of different PP grades is an issue for the MFR, the proportions of the different processing grades were also investigated and the potential of sorting by processing method to produce lower MFR recyclates was assessed. The analysis showed that the waste bales, although pre-sorted, still contained high amounts of contaminants. Injection moulding was found to be the predominant processing method in the bales, explaining the high MFR of PP recyclates. However, a sufficiently high amount of low MFR products was found in the bales, which seems promising for the production of low MFR recyclates. Seasonal variations in the composition of the waste bales were identified as one of the reasons for the inconsistent qualities of recyclates. These results highlight the importance of proper sorting and treatment of PP waste bales prior to reprocessing in order to obtain high-quality recycled products.

KW - contaminants

KW - melt flow rate

KW - polypropylene recycling

KW - recyclate quality

KW - sorting

KW - waste bales

UR - http://www.scopus.com/inward/record.url?scp=85184456424&partnerID=8YFLogxK

U2 - 10.1177/0734242X241227369

DO - 10.1177/0734242X241227369

M3 - Article

C2 - 38318839

AN - SCOPUS:85184456424

VL - 42.2024

SP - 767

EP - 775

JO - Waste Management and Research

JF - Waste Management and Research

SN - 0734-242X

IS - 9

ER -