Polyolefin Recyclates: Securing Constant Quality

Ensuring the consistent quality of polyolefin recyclates is of crucial importance for the plastics industry, particularly in view of the increasing demands for sustainability and resource efficiency. The social obligation to reduce greenhouse gas emissions and use resources efficiently will be reinforced by future political regulations, both nationally and internationally. The use of post-consumer recyclates (PCR) will be mandatory in the future and requires a shift away from linear value creation towards closed loops.

This transformation offers new opportunities, but also brings challenges for the plastics industry along the entire value chain.

Acting instead of reacting

Are you a compounder and want to ensure that your polyolefin recyclates are optimally stabilized? Are you a processor looking for solutions to ensure the stability of your processes and maximize the service life of your tools? Or do you come from an application background and want to ensure that the requirements for the components are also met when using plastic recyclates?

The joint research project aims to address these challenges and provide orientation and new assessment tools to better understand specific issues and derive targeted measures. The project will show whether and which material streams can be developed for the reliable production of qualitatively satisfactory polyolefin recyclates through cost-efficient, fast and reliable analysis as well as uncomplicated additivation and processing strategies.

Reliable use of polyolefin recyclates through simple evaluation strategies

The reliable and safe use of plastic products must also be ensured when using recycled plastics. Questions about long-term stability, the influence on mechanical properties and also emissions must be answered reliably without massively increasing the cost of material qualification.

Just like the question of the properties in the application, questions arise about the influences on processability when using recyclates from different material streams. How is the flow and degradation behavior, does the service life of the tools change due to deposits or corrosion, do black specks or emissions form during processing, are just some of the questions that arise at this point.

In order to achieve consistent quality in polyolefin recyclates from different sources and batches, it is first important to identify the general problem. This includes an assessment of the material flows and source materials available on the market. It is essential to know the differences between batches available on the market, including existing sources of information (e.g. product passports), and to know what challenges you have to expect when using plastic recyclates in practice, individually for your application.

The joint industrial project will show whether and which material streams can be tapped for the reliable production of qualitatively satisfactory polyolefin recyclates through cost-efficient, fast and reliable analysis as well as uncomplicated additivation and processing strategies.

The project is also intended to serve as an interdisciplinary platform for players from the entire value chain in order develop targeted solutions for the technical problems arising around the topic of "constant quality of polyolefin recyclates”.

Project focus & approach

Recording and evaluation of source materials and material flows

First, an assessment of the material flows and source materials available on the market is carried out. It is essential to know the differences between various batches and to understand the challenges that can be expected when using recycled plastics in practice.

A central goal of the project is the qualification of cost-efficient quality control of input materials. To this end, generally available and established analysis methods are applied to different recyclates. These include, for example, rheometry, which in part allows conclusions to be drawn about mechanical properties and processability, or OIT, which provides information about the residual stabilizer content and thus an estimate of a possible service life. DSC and TGA provide an assessment of thermal stability and process capability. Manual tests, such as determining the density using float-sink tests, offer a simple and cost-effective method for preliminary testing of material quality.

Offline and inline characterization

In addition to offline characterization, various inline process controls are also used to provide direct information on the properties of the recyclates produced during subsequent additive additions and blend compositions. These include, for example, online rheology or various inline spectroscopies. Continuous analysis enables quality fluctuations to be detected at an early stage and appropriate corrective measures to be initiated.

Compilation of a toolbox

In the further course of the project, these different methods of offline and inline characterization will be evaluated with regard to their suitability for various issues along the plastics value chain. The aim is to compile a toolbox of simple analysis methods and manual tests which, when combined, will allow conclusions to be drawn about the complexities of the condition of individual recyclate streams and will later be able to be used in practice without instrumentally and time-consuming characterization methods.

Production of exemplary formulations

Based on the condition assessment of various recyclates, exemplary formulations will be produced in the further course of the project using selected batches with the aim of upgrading the materials in terms of mechanical properties, long-term stability or weather resistance, for example. The use of additives such as stabilizers, adhesion promoters, light stabilizers or impact modifiers is essential here. The additive composition is adjusted to the previously determined conditions in order to achieve a constant quality of the end product, but also to avoid unnecessarily high additive concentrations.

Demonstration of the toolbox

In particular, it is to be demonstrated that a certain degree of harmonization of different batches according to the "blended whisky" model can be achieved through targeted blending of qualitatively different recyclates from different sources and batches in order to achieve a constant quality of the polyolefin recyclates.

Participating partners in this joint project will be able to use practical and cost-effective analyses to generate targeted formulations of high-quality polyolefin recyclates with consistent quality for their own applications or those of their customers

This joint project is aimed at companies along the value chain, from manufacturers of plastics and additives to companies that want to use recycled materials in individual components in their designs, with a particular focus on developers and producers of finished components:

• OEMs and manufacturers of plastic components in the construction, automotive, sports and leisure, electrical and electronic components and household appliances sectors who want to use polyolefin recyclates reliably and with consistent quality
• Raw material and additive manufacturers who are looking for new applications for their existing product portfolio
• Compounders and general plastics processors who want to prepare themselves for future challenges in the use of polyolefin recyclates