MTA-BME Research Group

Upcycling of crumb rubber after microwave devulcanization in rubber and thermoplastic elastomer formulations

Project ID:
OTKA K115949
Supported by:
Nemzeti Kutatási, Fejlesztési és Innovációs Hivatal (NKFIH)
1 September 2015 - 31 January 2019
Supervisor (BME):
Dr. Tamás Bárány

Participant researchers (BME):
Prof. Dr. h.c. mult. Karger-Kocsis József
Dr. Mészáros László
Dr. Morlin Bálint
Dr. Tamás-Bényei Péter
Simon Dániel Ábel
Pirityi Dávid Zoltán

Project summary

The economic recycling of used rubber products (tyres, conveyer-belt, production scrap) is a great challenge nowadays. Material recycling is the preferred way supported by legislative actions and economical/ecological arguments. Incorporation of crumb rubber (CR) in vulcanizable rubbers and thermoplastic resins is accompanied with prominent degradation in the mechanical properties. The extent of latter in a given rubber or thermoplastic system depends on the CR particle size and on its incorporated amount. Economical use of CR fractions requires that instead of using costly polymeric compatibilizers the surface of CR particles should be “activated”. This covers also the creation of dangled molecular chains which may entangle with those of the matrix thereby producing a strong interphase which guarantees improved mechanical performance. Our research strategy is to break up the sulphur crosslinked network and thus generate “active” molecules by microwave devulcanization of the CR before adding it in selected rubbers and thermoplastics. Accordingly, the project is devoted to the recycling and “upcycling” of microwave decomposed CR in rubber and thermoplastic resin-based recipes, respectively. Upcycling means the production of a value-added product, namely CR-containing thermoplastic rubbers. Major targets are: i) to enhance the amount of CR that can be added in fresh rubber without property penalty, and ii) to develop CR-containing thermoplastic rubbers which may compete with present commercial types based on their favorable property/cost balance.

Project results

Section 1
1 September 2015 - 31 August 2016

Section 2
1 September 2016 - 31 August 2017
In the 2nd year of the project we continued the research in three directions: i) microwave devulcanization of ground tyre rubber (GTR); ii) development of thermoplastic dynamic vulcanization (TDV) and iii) utilization of ultrafine GTR powder in a thermoplastic polymer.

Section 3
1 September 2017 - 31 August 2018
In the 3th year of the project we continued the research in two directions: i) microwave devulcanization of ground tyre rubber (GTR); ii) development of thermoplastic dynamic vulcanization (TDV) with devulcanized GTR. i) Microwave devulcanization of GTR Third year research was focused on further developing the microwave devulcanization techniquein order to increase the sol content (tested by the formerly detailed Soxhlet extraction method) of the microwave devulcanized water jet milled GTR (characterization of the GTR and the laboratory microwave oven can be found in former report). Spectrum of devulcanization rate characterization techniques was broadened from mere Soxhlet extraction tests by the involvement of Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Based on the results found in the literature, the solvent of the Soxhlet extraction was altered to toluene from acetone as well. Previous results showed, that the most effective treatment was at 230 °C, however, autoignition of the GTR samples often occurred in this case. Recent experiments showed that this issue can be eliminated by 200 °C treatment without holding the sample at elevated temperatures, while obtaining similar sol content results. Sol content can be further enhanced to 28% by a heat treatment of the GTR at 150 °C for 2 hours in a laboratory oven prior to microwave devulcanization. Another way to increase the sol content of the resulting dGTR is the utilization of a combined devulcanization technique, in which a thermomechanical treatment was implemented in a kneading chamber prior to microwave devulcanization. The sol content of the samples devulcanized by this combination of techniques resulted to be 34%, which can be interpreted as a considerable improvement compared to the initial 20%, reported in the previous report. Please note that these percentage values concerns to the whole cured rubber material (including fillers, additives as well), so if these val

Section 4
1 September 2018 - 31 January 2019

Project-related publications

  1. Kiss Lóránt, Simon Dániel Ábel, Petrény Roland, Kocsis Dávid, Bárány Tamás, Mészáros László: Ground tire rubber filled low-density polyethylene: The effect of particle size. Advanced Industrial and Engineering Polymer Research, 5, 12-17 (2022) 10.1016/j.aiepr.2021.07.001
  2. Simon D. Á., Bárány T.: Effective thermomechanical devulcanization of ground tire rubber with a co-rotating twin-screw extruder. Polymer Degradation and Stability, 190, 1-12 (2021) IF=5.03 Q1
  3. Simon D. Á., Pirityi D., Tamás-Bényei P., Bárány T.: Microwave devulcanization of ground tire rubber and applicability in SBR compounds. Journal of Applied Polymer Science, 137, 48351/1-48351/1-8 (2020) 10.1002/app.48351 IF=3.125 Q2
  4. Halász I. Z. , Kocsis D. , Simon D. Á. , Kohári A. , Bárány T. : Development of Polypropylene-based Thermoplastic Elastomers with Crumb Rubber by Dynamic Vulcanization: A Potential Route for Rubber Recycling. Periodica Polytechnica-Chemical Engineering, 64, 248-254 (2020) 10.3311/PPch.13962 IF=1.571 Q3
  5. Pirityi D. Z., Pölöskei K., Bárány T.: Etilén-propilén-dién-monomer gumi termomechanikai devulkanizációja hengerszéken. Polimerek, 6, 797-801 (2020)
  6. Simon D. Á., Pirityi D. Z., Bárány T.: Devulcanization of ground tire rubber: microwave and thermomechanical approaches. Scientific Reports, 10, 16587/1-16587/13 (2020) IF=4.379 Q1
  7. Simon D. Á., Halász I. Z., Karger-Kocsis J., Bárány T.: Microwave Devulcanized Crumb Rubbers in Polypropylene Based Thermoplastic Dynamic Vulcanizates. Polymers, 10, 767/1-767/14 (2018) 10.3390/polym10070767 IF=3.164 Q1
  8. Simon D. Á, Tamás-Bényei P., Bárány T.: Gumihulladék mikrohullámú devulkanizációja. Zöld Ipar Magazin, 7, 17-19 (2017)
  9. Kocsis D., Bárány T.: Polipropilén alapú termoplasztikus dinamikus vulkanizátumok fejlesztése. Polimerek, 2, 301-304 (2016)

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