Recycling quality

Maximising Recyclate Quality in Plastic Processing: Insights from Compounding Companies

Accurate measurement and characterisation of plastic waste streams can improve plastic recycling processes, according to findings from a recent study.

Written by: Nigel Visser | Updated: 06/10/2023
Reviewed by: Floris Gerritsen | Published: 12/10/2023

The Study:

Quality Aspects in the Compounding of Plastic Recyclate

Where: Pforzheim University of Applied Science

When: Published January 31, 2023, in Recycling

The Takeaway:

Key findings from the survey reveal that the input material has minimal influence on the frequency of quality problems in a study conducted among compounding companies in Germany about the challenges they face in plastic reprocessing. However, component production is a more demanding step that immediately highlights quality problems. Using more test procedures to determine the material composition of the input material stream can reduce the frequency of quality problems. The research also suggests that online methods do not necessarily mitigate quality problems but increase the subjective perception of their frequency. The companies surveyed state that the causes of quality problems are found in the previous processing steps, such as sorting and collection. The study concludes that the mechanical processing of plastic waste into recyclates is currently the most frequent method used in Germany. Still, various problems can occur in the recycling process that may affect the final recyclate quality. The study is limited by the small dataset, which increases the uncertainty factor and the subjectivity of the respondents’ answers.

What It Looked At:

An examination took place into the processes and practices of compounding companies responsible for processing post-consumer plastic waste into high-quality recyclate material. Compounding companies were chosen because they play a critical role in ensuring that recycled plastic meets the required quality standards for new products.

Setting their sights on compounding companies, the researchers conducted interviews to understand their processes for sourcing, sorting, cleaning, and processing plastic waste. They also looked at the different technologies and equipment used by these companies to ensure the highest possible quality of the recycled plastic produced. Notably, the researchers analysed the various quality control measures employed by compounding companies to ensure that their recycled plastic is consistent and high quality.

Moreover, the study also considered the economic factors that affect the quality of recycled plastic. Compounding companies must balance the need for high-quality recyclate material with the cost of processing and the price they can obtain for the final product. The researchers explored how compounding companies optimise their processes to maximise the value of their products while maintaining high-quality standards.

In addition, the study also examined the compounding process used by several companies, including large and small-scale operations. It looked at the types of equipment used in the process, the quality of the raw materials used, the additives added to the plastic, and the process conditions (such as temperature and mixing time).

And finally, the researchers also examined the final product quality of the recyclate produced by these companies. They looked at the physical properties of the recycled plastic, such as its tensile strength and elongation, appearance, and colour. They also tested the recyclate for potential contaminants, such as residual monomers or other impurities that could affect the quality of the recycled material.

Overall, the study examined the complex processes and factors involved in maximising the quality of recycled plastic produced by compounding companies. By examining these factors, the researchers aimed to identify key lessons that could be applied to help other companies in the plastic processing industry improve the quality of their recycled plastic.

What It Found:

The authors of the article make a compelling case for the importance of accurate and standardised measurement and characterisation techniques for plastic waste, specifically in the context of recycling. The authors argue that the lack of standardised methods has led to inconsistencies in reporting and hindered progress in improving plastic recycling processes.

Furthermore, the article also highlights the limitations of current techniques and the need for further research to develop more efficient and reliable methods for measuring plastic waste. Additionally, the authors suggest that greater collaboration among researchers, policymakers, and industry stakeholders is necessary to address the challenges of plastic waste and promote sustainable solutions.

To sum it up, the article underscores the need for heightened precision, accuracy, and uniformity in measurement techniques. As well as greater collaboration and innovation to improve plastic recycling processes and mitigate the environmental impact of plastic waste.

Why It Matters:

In the grand scheme of enhancing plastic recycling processes and comprehensive metrology for plastic recycling, this study serves as a reminder of the pivotal role of accurate measurement and characterisation. It underscores the necessity of standardised plastic waste characterisation and cooperation among stakeholders across the value chain, fostering a more circular and sustainable plastics economy.

However, it’s essential to acknowledge the study’s focus on the mechanical properties of recycled plastic, omitting other vital factors such as chemical and thermal properties. The study’s limited use of only two types of plastics implies that the results may not be universally applicable. It also doesn’t explore the impact of diverse recycling processes on recycled plastic quality.

The following steps involve conducting broader research encompassing various plastics to validate the results across diverse materials. Examining the effect of different recycling processes on recycled plastic quality will further optimise recycling methods. Investigating the influence of recycled plastic age on its mechanical properties will provide insights into its suitability for specific applications.