Functionalization in the Injection Molding of Thermosets

by | Apr 24, 2018

Aachen Institute of Plastics Processing studies fiber-reinforced lightweight parts with a thermoset matrix.

Highly load-resistant, continuous fiber-reinforced and functional plastic parts have enormous potential not only for the automotive and aviation industries. For this reason, the Institute of Plastics Processing (IKV) in Industry and the Skilled Crafts at RWTH Aachen University is examining possibilities for the economical production of fiber-reinforced and functional plastic (FRP) parts with a thermoset matrix by the injection molding process.

The mounting demand for plastic parts reinforced with continuous fibers is based on their high mechanical strength with up to 25% less weight compared with metal parts. For this reason, their production and in particular the economic benefits of the process and the reduction of production steps with short cycle times have been the subject of various research projects. Whereas FRP parts with a thermoplastic matrix are already being produced on an industrial scale and are in widespread use, IKV is now occupied for the first time with the production of continuous fibre-reinforced lightweight parts with a thermoset matrix. Because of their better low-temperature resistance and higher mechanical and thermal load resistance, thermosets are superior to thermoplastics in many applications.

In the present research project, the IKV team is examining the possibilities for producing lightweight parts with a thermoset matrix. Similar to the already known process involving the integrated molding and back-injection of thermoplastic FRP, the aim is thus to combine the favorable lightweight properties with the greater part complexity that is possible with injection molding, and apply this to thermoset parts, too. Two innovative process routes are used: a two-step process route involving the backmolding of parts previously produced in the established RTM process, and a single-step route involving the backmolding of towpreg/prepreg materials, which, integrated into the process, cure in the injection molding process. Both methods have the advantage of a reduced number of production steps compared with conventional functionalization strategies such as bonding or riveting, and of shorter cycle times.

Backmolded RTM specimens produced by the thermoset injection molding process (photo: IKV)

The attained research results such as process parameters, attainable part complexity, adhesion/bonding properties and the technological and economic evaluation can help in future to increase not only the complexity of the component but also the functional integration, and thus tap new fields of application for thermoset FRP parts.

The research project IGF 9EWN is financed by the AiF as part of the program of the Federal German Ministry for Economic Affairs and Energy for funding Joint Industrial Research (IGF), based on a resolution by the German Bundestag.

More about the Institute of Plastics Processing (IKV) here.

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