Joint research project

Development and analysis of the effect of 3-dimensional reinforcing frame structure with AM from renewable resources on the morphological and mechanical properties of injected polymer composites

Project leaders
Mauro Zarrelli, Tamas Tabis
UNGHERIA - HAS (MTA) - Accademia Ungherese delle Scienze
CNR/HAS triennio 2019-2021 2019-2021
Chemical sciences and materials technology
Thematic area
Chemical sciences and materials technology
Status of the project

Research proposal

Relevance of the topic: due to environmental regulations and decreasing amount of raw materials, the mass and load optimization of engineering products are receiving more emphasis. Nowadays, polymer composites are more and more used in engineering applications as load-bearing structures and injection molding is one of the most often used polymer composite processing technologies, due to its high productivity and reproducibility. However, for injection molded composites, a disadvantage is that the orientation of the reinforcing fibers is determined by the flow conditions and also fiber breaking occurs during processing, thus the reinforcing possibilities of the fibers cannot be utilized to the full. In most cases, researchers attempt to solve the problem by optimizing the manufacturing technology. By contrast, we set out to develop a complex solution for the problem, which facilitates better adaptation of the reinforcing fibers and structure in injection molded structures to conditions of use, and results in better structural integrity and load bearing. The overall goal of the project is to create a complex design methodology with which a tailor-made reinforcing structure can be made in injection molded parts as a separate 3D printing step. It makes the production of a composite frame possible with directed mechanical properties within the injection molded product in one step. The reinforcing fibers are oriented previously and they keep their planned orientation during the injection molding process.
The aim of the project and cooperation: The main goal of our research is to work out a complex design and simulation methodology and procedure with which a composite frame with oriented mechanical properties can be created in injection molded parts as a previous and separate 3D printing step. Accordingly, the 3D printed frame (reinforced structure) with desired fiber orientation is placed into the mold of an injection molding machine and over-molded with thermoplastic polymer to create the final product. Both the loads affecting the final product and the loads occurring during the injection molding onto the preform have to be taken into account, thus the reinforcement can be utilized to the full and the mass of the product can be minimized. In addition to elaborating the methodology, materials science development is also necessary, where the flow properties of the matrix is analyzed with numerical methods, the relationships between the 3D printing strategies and the mechanical and morphological properties of the frame are determined, as well as the embed-ability of the reinforcement structure and the efficiency of it working together with the injection molded matrix system are examined.
In the previous research project, within the frame of bilateral agreement between CNR and MTA, period 2013-2015, Poly(Lactic Acid) based biocomposites were developed, that could be successfully applied in engineering applications due to their improved mechanical and thermal properties by means of additive manufacturing technique. Accordingly, the goals of the project were achieved as well as highly qualified papers were published as the results of the cooperation (1 international journal papers with high impact factor, 1 conference proceeding and 1 national (Hungarian) journal paper). The success of the cooperation contributed to the acquirement of PhD degree for the former PhD students of András Suplicz and Norbert Krisztián Kovács from MTA side; and Dr. Norbert Krisztián Kovács assistant professor is now involved within this submitted proposal as a young researcher.
The benefit of the scientific cooperation is that the two research institutes can perform complementary measurements and subtasks. The Hungarian partner has very strong theoretical and practical background as well as well-equipped laboratory regarding processing of polymers. Accordingly, in Hungary, by using the 3D printing (additive manufacturing) and injection molding, we are capable of developing the specimens for the research as well as we are capable of performing the mechanical characterization. Additionally, the Italian partner (CNR) has also a very strong background in experimental mechanics and testing therefore in Italy it will be possible to carry out a complete campaign for testing and characterization of the regarding the orientation of the fibers during 3D printing to develop 3D printing strategies and patterns, thermal, degradation and fire retarding properties of the specimens.

Research goals

It is expected that by applying the developed methodology, the characteristics of the reinforcing structure (orientation, fiber content etc.) could be made independently of flow conditions during injection molding and could be changed in each point according to the load and to the desire of the product designer like in the case of thermoset composite materials. It is also expected that that fiber breakage (shortening) occurring during "conventional" injection molding could also be greatly reduced, thus the reinforcing effect and efficiency of fibers would be increased and recyclability by re-melting would be better facilitated. This method could be used in the case of 100% recyclable plastics and also for biodegradable polymers, therefore the load on the environment can be further reduced with its use.
The goal of this proposed activity is to continue the formerly established and mutually successful cooperation between MTA and CNR (2013-2015, number of the contract: SNK 86/2013) and to open a novel research area with this new bilateral project proposal.
The final objective of the activity will be mainly to explore the potentiality of these novel frame structures in order to achieve a higher performance 3D reinforcement geometrical structure. The necessary characterization of the forming material and the evaluation test over the final structures characterized by the developed 3D reinforced framework will be performed and made available at the end of the bilateral project.

Last update: 18/07/2024