Material determination at the touch of a button using NIR spectroscopy

Plastics industry strives to recycle plastics as comprehensively as possible. However, this is not always so easy – especially when different types of plastic are difficult to distinguish visually. This is when near-infrared spectrometers (NIR) come to the rescue, identifying the types of plastic and thus facilitating further processing.

The company trinamiX manufactures a mobile NIR spectrometer that is particularly suitable for identifying multi-material and mono-material films. However, the application is also able to recognize 30 types of plastics, including standard plastics (HDPE, LDPE, PP, PET, PS, PVC) and technical plastics (PA, ABS, PC, PLA). It is also able to quantify mixtures of PE and PP. In this interview, Dr. Nils Mohmeyer, Director Mobile Spectroscopy at trinamiX, explains the advantages for users and the industries for which the NIR spectrometer is suitable.

Dr. Mohmeyer, for which industries and end users is your product suitable?

Dr. Nils Mohmeyer: The mobile NIR spectroscopy solution from trinamiX can be used along the entire value chain: starting with the design of industrially sortable packaging, through quality control of incoming and outgoing plastics, to sorting for better recyclability. Mobile identification of plastics and textiles is of interest to the manufacturing industry (in particular plastic and plastic packaging manufacturers), the textile and clothing industry as well as recyclers of plastics and textiles.

As the solution can be used without prior knowledge of spectroscopy and has an intuitive user interface, it can be used at the sorting plant in the recycling center as well as in the laboratory, incoming goods inspection and in the packaging design studio.

In order to meet the specific requirements of textile recyclers, we have developed a semi-automatic system that is built into a sorting table and triggers the scans using an integrated sensor.

How does the NIR spectrometer distinguish between different types of plastic?

Mohmeyer: An NIR spectrometer can distinguish between different types of plastic based on their spectral properties. Each plastic has a unique spectral signature, which is generated by the absorption and reflection properties in the near-infrared light range. The spectrometer captures these patterns and enables the identification of plastic types.

What impact does the precise identification of plastic types have on the efficiency and quality of the recycling process?

Mohmeyer: Thanks to the clear identification of different types of plastic, materials can be separated by type. This is an important prerequisite for efficient recycling and high-quality recyclates and therefore the basis for a circular economy. In addition to sorting, identification is also important for quality control. Reliable material identification with the mobile NIR spectrometer from trinamiX significantly simplifies the inspection of incoming materials and the release of sorted plastic and textile bales. It also supports non-conformance management and the efficient management of complaints, reducing the risk of costly errors and delays. Our solutions enable companies not only to perform spot checks, but also to comprehensively document incoming and outgoing material flows, visualize and analyse them, thus creating comprehensive transparency for manufacturers and recyclers of plastics.

What are the benefits of cloud-based data analysis and the connected customer portal for recyclers and manufacturers?

Mohmeyer: The data measured with the spectrometer is analyzed using chemometric models in the cloud provided by trinamiX. This ensures that up-to-date and powerful algorithms are available at all times. All measurements are stored in the cloud and can be accessed simultaneously both in the app and in the customer portal. Users can access current and historical data at any time via the customer portal, even for different devices and measurement campaigns. This opens up a wide range of possibilities for comparing measurements, analyzing and optimizing processes and documenting quality controls. Real-time monitoring is also possible.

The identification of plastics also works without an internet connection. The data is then stored on the device and sent to the cloud at the next opportunity. An advantage in regions with unreliable mobile networks.

How long did the development take and what challenges did you have to overcome?

Mohmeyer: trinamiX started developing infrared sensors in 2016 and launched the first complete spectroscopy solution in 2020. Since then, we have been continuously improving our products and applications and adding new features. A particular challenge was the miniaturization of the hardware and the parallel development of digital solutions and applications. However, thanks to the good cooperation of all developers, we have mastered these tasks well.

What feedback have you received from customers about using the mobile NIR spectrometer?

Mohmeyer: Very positive! Customers have confirmed that they can identify plastics within seconds and with ease. They are particularly positive about the compact size of the device and the fact that they can use it to go directly to the delivered bales to distinguish the types of plastic on site.

When it comes to areas of application, our customers repeatedly mention quality control. Here, the trinamiX solution is used very frequently, for example when checking plastic mixtures. They compare a product sample with the reference sample. The fast result thanks to the trinamiX spectrometer often saves up to a day's testing time in the laboratory.