VaTuS: Working Together to Establish Standards for Silicone-Thermoplastic Composites

The VaTuS research project—composites made of thermoplastic and silicone—marks the start of a new collaboration between POLAR-FORM Werkzeugbau GmbH and the Department of Plastics Engineering at the University of Kassel. The 24-month project is being carried out as part of the WIPANO funding program—Knowledge Transfer through Standardization.

Silicone-thermoplastic composite parts offer great potential for demanding applications—for example, in the automotive industry, medical technology, robotics and automation, plant engineering, and consumer goods. In multi-component injection molding, the properties of the thermoplastic component can be combined with the versatile properties of liquid silicone rubber (LSR). At the same time, assembly processes can be eliminated, and components can be manufactured with integrated functions and cost-effectively in high volumes.

However, a key challenge to date has been reliably and comparably evaluating the adhesion between silicone and thermoplastics. Existing test methods are only applicable to a limited extent to the specific properties of LSR-thermoplastic composites. VaTuS addresses precisely this issue and aims to develop a specific, reproducible test methodology for these composite materials.

From Research to Industrial Application

Among other things, the project focuses on investigating suitable material combinations, tool and process parameters, and the influence of pre- and post-treatments on bond strength and long-term durability. In addition, simulation-based methods using finite element modeling and injection molding simulation are being investigated to make the design of future components more efficient and robust.

The results will ultimately be incorporated into practical best-practice documentation and serve as the basis for a future standardized testing method. One of the goals is to incorporate these findings into a new testing standard, such as DIN ISO 813-3. To this end, the project is working closely with the German Rubber Industry Association (wdk) and the DIN Standards Committee for Elastomer Technology (NET).

Science and Toolmaking Pool Their Expertise

The University of Kassel is contributing its many years of research experience in silicone rubbers, hard-soft composites, material characterization, and simulation-based design to the project. POLAR-FORM is primarily responsible for the application-oriented aspects of tooling and process engineering and contributes its extensive experience in sophisticated LSR-thermoplastic multi-component injection molding.

The project is also supported by numerous associated partners from various sectors of the industrial value chain. This ensures that the methods developed are aligned with real-world requirements from the outset and that their practical applicability is continuously validated.

Greater Safety and Efficiency for Future 2K Applications

VaTuS aims to lay an important foundation for developing and manufacturing silicone-thermoplastic composite components more safely, reproducibly, and efficiently in the future. Standardized testing procedures and robust design guidelines can shorten development times, reduce coordination efforts, and prevent scrap. At the same time, the project aims to lower the barriers to entry into this demanding technology, particularly for small and medium-sized enterprises.

For POLAR-FORM, the project thus represents another step toward further developing its own expertise in the field of sophisticated multi-component and silicone applications in collaboration with academia and industry—and actively helping to shape future standards for LSR-thermoplastic composites.