MTA-BME Research Group

Developing of increased load-ability polypropylene and environmental friendly material based bale twines

Project ID:
Supported by:
Nemzeti Kutatási, Fejlesztési és Innovációs Hivatal (NKFIH)
1 January 2020 - 31 December 2023
Supervisor (BME):
Dr. Tamás Tábi
Participant researchers (BME):
Dr. Tábi Tamás
Dr. Bárány Tamás
Dr. Molnár Kolos
Dr. Bakonyi Péter
Prof. Dr. Vas László Mihály
Dr. Kmetty Ákos
Virág Ábris Dávid
Csézi Gergely
Varga László József
Consortium partners (BME):
Tama Hungary Kft. (konzorciumvezető)

Project summary

When cereals are harvested, the straw is compacted by dedicated machines into cylindrical or rectangular bales and then stored this way. In order to keep the finished bale in shape, various binders are used, the most common one is the highly oriented polypropylene (PP) twine or netting that is manufactured by advanced technologies. It is common for relatively rigid twines to break during machine knotting, hence the time to round bales increases significantly. On the other hand, weather conditions (rainfall, sunlight, temperature) during the storage of the finished bales can cause the twines to break, making subsequent utilization difficult. By improving the properties of baler twines, baling itself and picking up the bales become more stable and simple, less time consuming and safer, and thus increase the efficiency of bale forming and handling. Nowadays, many manufacturers are continuously developing their baling machines to best meet the needs of a wide range of customers. The customer community needs more than just a robust machine these days. They have a demand for a multitude of high-quality technical solutions that can make their day-to-day work significantly easier and faster. They need to ensure control from a comfortable cab, and the high-performance baler should create a sufficiently compact, securely fixed bale. This project wants to work out a solution to this important market demand, a problem which current machine manufacturers and farmers are experiencing. Due to the increased transportation costs, there is a demand to be able to transport the most forage and straw in a given volume, which is why machine manufacturers are producing balers working at higher and higher pressures. The approach used so far has been to use thicker twines, which have now reached their limits as under 100 m/kg the product is too thick and unmanageable from both the production and the application side. A reasonable and the only feasible solution is to produce twines with higher tensile and knot strength in the lightest (m/kg) form possible. This approach also meets the current societal expectation of appropriate plastic waste management, as the mass of plastic used decreases as the bale size increases. As part of the planned research project, TAMA, in consortium with BME-PT, would advance a twine for baling for which we identified two major directions of research. The first one is the development of the existing PP bale cords and the related manufacturing technology in order to achieve greater tensile strength, greater elasticity (greater elongation), lower weight and lower heat relaxation tendency and, as a result, the development of a more compliant twines. In this case, it is expected that the baling twines and the knot created will break at a higher force, thus increasing the efficiency of the baling process and reducing the time required. The other main direction is to develop the production technology for the twines originally made of PP in order to change it for an environmentally friendly, renewable resource-based polymer that is also biodegradable (so-called biopolymer). In this case, even greater environmental awareness can be achieved by replacing PP bale twines with biopolymer-based ones, which eliminates the direct deposition of conventional, petroleum-based, non-biodegradable plastics onto fertile lands. For both directions of the current development, our goal is to create a ready-to-use, practical bale twine. The competitors' developments is pointing towards one-way, thicker products, suggesting that they want to solve the problem with even greater amounts of plastics. Therefore, we believe that the successful development would provide a significant competitive advantage for the company.

Project results

Section 1
1 January 2020 - 31 December 2020
In the 2019-1.1.1-PIACI-KFI-2019-00335 commercial R&D project, we performed research and development together with TAMA Hungary Kft., during which we carried out the following tasks: - We did a thorough literature review concerning the material structure of the polypropylene used for producing string production, and the changes in material structure during string production. We also explored the literature of the applicability of biopolymers in the case of oriented structures (“Literature review”). - We assessed the production line manufacturing the string together with TAMA Hungary Kft., and took samples with the help of the employees of the company: semi-finished products (film) and finished products (string), which we extensively analyzed in the laboratory of the Department of Polymer Technology at BME. - TAMA Hungary Kft. employees produced a large number of string samples varying material composition, machine settings and environmental parameters. We extensively analyzed these string samples in the laboratory of the Department of Polymer Engineering with various kinds of equipment, including the string tensile testing fixture designed and produced within the project. - Based on the results obtained in the project, we analyzed the volume–temperature relationship of polypropylene and mathematically modelled its relationshop with DSC (differential scanning calorimetry). - Based on the results, we made a suggestion concerning the modification of the configuration of the production line, and explored the estimated potential left in the production line for further development. We prepared a report for each task, a total five reports with a total length of 277 pages.
Tensile testing of experimental twines at the Department of Polymer Engineering, BME. The twine tester was designed and manufactured within the framework of the project

Section 2
1 January 2021 - 31 December 2021

Section 3
1 January 2022 - 1 December 2022

Section 4
1 January 2023 - 31 December 2023

Project-related publications

  1. Tábi T., Pölöskei K.: The effect of processing parameters and Calcium-stearate on the ejection process of injection molded Poly(Lactic Acid) products. Periodica Polytechnica-Mechanical Engineering, 66, 17-25 (2022) 10.3311/PPme.18246
  2. Tábi T.: Fröccsöntött politejsav biopolimer sorozatgyárthatóságának elemzése. in 'XXIX. Nemzetközi Gépészeti Konferencia (OGÉT 2021) Románia. 2021.04.23.,200-203 (2021)
  3. Csézi G., Tábi T.: Orientált biopolimer szerkezetek vizsgálata. in 'XXIX. Nemzetközi Gépészeti Konferencia (OGÉT 2021) Románia. 2021.04.23.,101-105 (2021)
  4. Tábi T., Ageyeva T., Kovács J. G.: Improving the ductility and heat deflection temperature of injection molded Poly(lactic acid) products: A comprehensive review. Polymer Testing, 101, 107282/1-107282/36 (2021) 10.1016/j.polymertesting.2021.107282 IF=4.282 Q1
  5. Tábi T.: Tények és tévhitek a biopolimerekkel kapcsolatban - I. rész (másodközlés). Polimerek, 7, 298-301 (2021)
  6. Tábi T.: Tények és tévhitek a biopolimerekkel kapcsolatban - II. rész (másodközlés). Polimerek, 7, 337-340 (2021)

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