Comparison of Properties with Relevance for the Automotive Sector in Mechanically Recycled and Virgin Polypropylene

Abdelhak Ladhari,Henning Stoll,Esra Kucukpinar,Sven Sängerlaub

doi:10.3390/recycling6040076

Abstract

Polypropylene (PP) has a high recycling potential. However, the properties of mechanically recycled PP (R-PP) have not been fully compared to those of virgin PP (V-PP). Therefore, in this study, properties of R-PP and V-PP were compared using data from recyclers, virgin plastic suppliers, and the literature. The properties of recyclates could not be directly correlated either with the properties of the virgin polymers from which the recyclates were made or the recycling parameters. It was found that the MFR of R-PP was higher; MFR R-PP had a median value (m) of 11 g/10 min while MFR V-PP had a median value of 6.3 g/10 min (at 230 °C and with 2.16 kg). In terms of mechanical properties, in many cases R-PP exhibited stiffer and more brittle behavior, with a slightly higher Young’s modulus (ER-PP = 1400 and EV-PP = 1200 MPa), a reduced elongation at break (ɛbR-PP = 4 l.-% and ɛbV-PP = 83 l.-%), and notched charpy impact strength (NCISR-PP = 4.8 and NCISV-PP = 7.5 kJ/m2). However, the values for every property had a broad distribution. In addition to existing information from the literature, our research sheds fresh light on the variation of the characteristics of recycled polypropylenes presently on the market.

Highlights

The melt flow rate (MFR) is a parameter that indicates the resistance to flow of a
The melt flow rate (MFR) is a parameter that indicates the resistance to flow of a polymer melt at a particular temperature and applied force over a specified polymer melt at a particular temperature and applied force over a specified length of time
As expected from and in harmony with the general theory of polymer processing and polymer physics, the findings of our study indicate that the median of market-available recycled polypropylene is lower for the impact strength and the elongation at break but slightly higher for the tensile modulus compared to market-available virgin polypropylene

Summary

Introduction

Charles Goodyear developed vulcanized rubber by altering the mechanical characteristics of natural rubber from the Pará rubber tree. This rubber was the one of the world’s first polymers; it had a high relevance for cars and was quickly adopted for use in automobile tires [1]. The potential to create a low-cost petroleum-derived gasoline provided a cohesive and dependable raw material for the manufacturing of low-cost plastics [2]. This presented the automobile sector with many possibilities. The automotive industry ranks third in terms of plastics consumption, after packaging and building and construction [3]

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