HUN-REN-BME Research Group






Thermoplastic elastomers from recycled polyolefins and tires (HERO)

Project ID:
2023-1.2.1-ERA_NET-2023-00003
Supported by:
Hungarian National Research, Development and Innovation Office (NKFIH)
Term:
1 January 2024 - 31 December 2026
Contracted amount of funding:
48509028
Supervisor (BME):
Dr. László Mészáros

Consortium partners (BME):
Hochschule für Technik und Wirtschaft (HTW) Dresden
National Research and Development Institute for Textiles and Leather (INCDTP)
Monofil SRL

Project summary

The amount of plastic and rubber waste is increasing rapidly worldwide: between 2000 and 2019 the global production of polymer waste exceeded 350 million tonnes, while only a small fraction of this material is actually recycled. Mixed polyolefin waste streams and end-of-life tires are particularly difficult to recycle because different polymers are generally incompatible with each other, while crosslinked rubber cannot be processed using conventional melt-processing technologies. Therefore, the development of new, efficient and environmentally friendly technologies is required to enable the value-added utilization of polymer waste and to support the transition toward a circular economy. The HERO project aims to develop high-performance thermoplastic elastomers (TPEs) based on recycled polyolefin waste (PE, PP) and ground tire rubber. A central element of the research is the development of an efficient separation technology for polymer waste streams and the surface modification of rubber particles using electron-beam treatment based on ionizing radiation. This approach enables improved interfacial adhesion between the rubber particles and the polyolefin matrix, allowing the production of composites with favorable mechanical and thermal properties. The project also aims to develop materials that can be repeatedly recycled and that follow the principles of “design from recycling” and “design for recycling”. The project will be implemented through a multi-stage approach by a consortium consisting of universities, research institutes and industrial partners. First, an electron-assisted electrostatic separation method will be developed to efficiently separate mixed polyolefin waste streams, while radiation-induced surface activation will be applied to modify the rubber powder. Subsequently, TPE composites will be produced in laboratory and pilot-scale experiments using extrusion and injection moulding, and their mechanical, thermal and morphological properties as well as recyclability will be investigated. The final goal of the project is the validation of the technology in an industrial environment (TRL 5), together with life-cycle and economic assessments, in order to contribute to environmentally friendly utilization of polymer waste and to strengthen the circular economy in Europe.

Project results

Section 1
1 January 2024 - 31 December 2024
Nowadays, vast amounts of rubber waste are generated worldwide, which are primarily incinerated or subjected to pyrolysis. Consequently, the valuable raw materials contained within them are lost or can only be downcycled. The optimal solution is material recycling, the first step of which involves producing ground tire rubber (GTR) from end-of-life tires. This can be incorporated into various matrices to manufacture new products. To improve the weak interfacial adhesion between the phases, compatibilization methods must be applied. We began our work with a literature review, from which we prepared a scientific review article, and then commenced comprehensive investigations on the ground rubber. The measurements started with the determination of the particle size distribution; the largest fraction falls within the 500–250 μm range, making it suitable for the project. For the morphological analysis of the GTR, scanning electron microscopy (SEM) was utilized, revealing a complex morphology. To determine the thermal properties, thermogravimetric analysis (TGA) was conducted. The sol fractions of the GTR were determined via Soxhlet extraction. Based on the results, we concluded that the GTR did not undergo significant degradation during the milling process, thus it can be used as a filler in thermoplastic elastomers. The crosslink density of the ground rubber was determined through swelling tests. The GTR possesses a typical crosslink density, meaning it can be used for the production of thermoplastic elastomers. We verified that the properties of the waste ground tire rubber are appropriate for the purposes of the project.
Scanning electron micrograph showing the complex morphology of the waste ground rubber used in the project (1000x magnification).

Section 2
1 January 2025 - 31 December 2025
The adhesion between the investigated ground rubber and the matrix is insufficient; therefore, it is necessary to develop a technology capable of enhancing it, in order to optimize the mechanical properties of the material. Based on the consortium's decision and feasibility considerations, we implemented this by utilizing ionizing radiation treatment on the matrix, along with compatibilizing agents. Initially, the German partner subjected the matrices to ionizing radiation treatment; subsequently, we prepared a blend in an internal mixer, from which sheets were produced using a hydraulic press. For the tensile testing, standard test specimens were die-cut from the pressed sheets. The mechanical properties of the materials were evaluated across several experimental designs, yielding progressively better results due to the decreasing radiation dose and the variation of different compatibilizing agents. The elongation at break increased by more than 500%; thus, we successfully and significantly enhanced the most critical property of the thermoplastic elastomers from an application perspective. Based on the results, it can be concluded that radiation treatment alone was unable to sufficiently improve adhesion, nor was the radiation-initiated grafting technology; therefore, we combined this with the application of compatibilizing chemicals. By the end of Milestone 2, combining radiation treatment with compatibilizers resulted in a significant improvement in mechanical properties for end-use applications.

Section 3
1 January 2026 - 31 December 2026



Project-related publications


  1. Kiss L., Gohs U., Czvikovszky T., Mészáros L.: Recycling of polymers by ionizing radiation: the potential applications of radiation-induced effects in polymers – a review. Radiation Physics and Chemistry, 245, 113872/1-113872/10 (2026) https://doi.org/10.1016/j.radphyschem.2026.113872 IF=3.3 D1
  2. Mészáros L., Kiss L., Constantinescu D., Harre K., Gohs U., Stelescu M.: Recycling of waste tyre rubber containing natural rubber with the aid of ionising radiation. in 'Third International Conference on Applications of Radiation Science and Technology, #ICARST2025 Vienna, Austria. 2025.04.07-2025.04.11.,52-52 (2025)
  3. Zeumer R., Gohs U., Harre K., Mészáros L.: Life cycle assessment for thermoplastic elastomers based on electron beam-assisted recycling of polyolefin and rubber waste. in 'Third International Conference on Applications of Radiation Science and Technology, #ICARST2025 Vienna, Austria. 2025.04.07.-2025.04.11,124-124 (2025)
  4. Kiss L., Szakács Á., Homlok R., Tegze A., Mészáros L.: Gumiőrlemény felületaktiválása víz közegű, elektronsugárzásos kezeléssel és alkalmazása gumikeverékekben. Polimerek, 9, 90-96 (2025)
  5. Stelescu M. D., Georgescu M., Sönmez M., Kiss L., Constantinescu D.: Study on the composition of vulcanized rubber mixtures from waste tire. in 'The 10th International Conference on Advanced Materials and Systems (ICAMS 2024) Bukarest, Románia. 2024.10.30-2024.10.31.,253-560 (2024)
  6. Kiss L., Molnár M. J., Mészáros L.: Improving the mechanical properties of vulcanizates containing ground tire rubber: Recipe optimization with the Taguchi method. Polymers for Advanced Technologies, 35, e6389/1-e6389/10 (2024) 10.1002/pat.6389 IF=3.4 Q2
  7. Kiss L., Berényi A. E., Németh M., Tegze A., Homlok R., Takács E., Mészáros L.: Enhanced surface activation of ground tire rubber via the radiolysis of water for effective rubber recycling. Heliyon, 10, e37454/1-e37454/11 (2024) 10.1016/j.heliyon.2024.e37454 IF=3.6 Q1

© 2014 BME Department of Polymer Engineering - Created by: Dr. Romhány Gábor