Quality Aspects in the Compounding of Plastic Recyclate

Abstract

Compounding is the final processing step for quality adjustment and control before recycled thermoplastic polymer material can be introduced into production processes. Motivated by the need for higher recyclate shares, the research question is which quality problems recycling compounders are encountered in practice, where they occur, and which mitigation options might be reasonable. Therefore, an online survey with 20 recycling compounders based in Germany was conducted asking about typical processing steps and processed materials, test procedures for quality assurance, quality problems, and possibilities for reducing quality problems. Results show that compounders mainly name impurities and contaminations of the input material as challenging and the reason for quality problems. The study shows that the problems are not dependent on the material input type. Quality problems occur along the entire secondary value chain, with companies manufacturing components themselves being particularly affected. The composition determination of the input materials helps to minimize quality problems.

Special Issue “Feature Papers in Recycling 2022”

“…The compounding process produces the recyclate, after which there is a final step for quality controls before re-introducing the materials in the productive cycle. The study in [3] was based on the analysis of survey questionnaires coming from 20 German recycling compounders to assess the encountered quality problems and related solutions. The study stated that impurities and contaminations in the input material constitute the primary reason for quality problems, independently of the plastic type.…”

Influence Analysis of Modified Polymers as a Marking Agent for Material Tracing during Cyclic Injection Molding

“…As different batches and material streams have different material properties, the identification of the different classes of recyclates is required [ 5 , 9 , 32 , 36 , 37 ]. In Auer et al [ 37 ], the current problems of recycling and their causes were summarized.…”

“…As different batches and material streams have different material properties, the identification of the different classes of recyclates is required [ 5 , 9 , 32 , 36 , 37 ]. In Auer et al [ 37 ], the current problems of recycling and their causes were summarized. Although the use of methods to determine material composition is a solution to reduce quality problems, Auer et al [ 37 ] evaluated the current sorting technology as inappropriate.…”

“…In Auer et al [ 37 ], the current problems of recycling and their causes were summarized. Although the use of methods to determine material composition is a solution to reduce quality problems, Auer et al [ 37 ] evaluated the current sorting technology as inappropriate. For this, Auer et al [ 37 ] mentioned the use of tracing technologies that can sort the previously unsortable materials.…”

“…Although the use of methods to determine material composition is a solution to reduce quality problems, Auer et al [ 37 ] evaluated the current sorting technology as inappropriate. For this, Auer et al [ 37 ] mentioned the use of tracing technologies that can sort the previously unsortable materials. Modified polymers were evaluated as a suitable material-inherent tracing technology for use in polymer processing manufacturing [ 38 ].…”