Is civil engineering easy or aviation

Lightweight construction for aviation and traffic: sustainably repair or recycle CFRP components

Carbon fiber reinforced high-performance plastics (CFRP) have become a permanent fixture in modern aircraft. However, repairs are very complex or not possible at all. Most of the time, the entire component has to be replaced. At the PYCO research area of ​​the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam, a simple, inexpensive and energy-saving process for sustainable repairs has been developed. In addition, entire components can be completely recycled, whereby the expensive carbon fibers can also be recovered. The researchers will present their development at the JEC World trade fair in Paris from March 8 to 10, 2016 in Hall 5a, Stand D52.

Composite materials made from cross-linked polymers - so-called thermosets - which are reinforced with carbon, glass or natural fibers, have a rich spectrum of properties that are important for the aerospace, automotive and wind power, marine and automotive industries Railway construction or civil engineering grew enormously. But even the best material can be damaged or show signs of wear and tear. The engineers then have to decide whether the defective area can be repaired by laborious and expensive patching or whether the entire component has to be replaced.

"The repair and recycling of polymer-based composites are inextricably linked to resource efficiency and sustainability," explains Dr. Christian Dreyer, head of the research area Polymer Materials and Composites PYCO at Fraunhofer IAP. "Finite raw materials make sustainable management and thus the use of recyclable and repairable polymer materials more and more important," says Dreyer.

The researchers have therefore developed a method for the repair and chemical recycling of fiber-reinforced thermosets. These are used in particular as matrix resins in composites for highly stressed components. The cross-linked polymers form a very rigid structure that gives the component its shape. But it is precisely this structure that poses a problem for repair or recycling. Because once cured, thermosets, unlike thermoplastics, cannot easily be chemically decomposed.

Repair and recovery - simple, inexpensive and energy-saving

"We have developed a gentle and fast process for chemical recycling that enables highly crosslinked plastics to be broken down into their original components," explains Dreyer. In addition to the complete recycling of a component, this development also enables local repairs. The resin matrix is ​​gently removed from the defective area without significantly affecting the mechanical properties of the reinforcement fiber. The exposed fibers are then refilled with a repair resin and cured.

The new process also sets standards when it comes to recycling. So far, discarded components were either burned or crushed and used as filler material. With chemical recycling, the Fraunhofer researchers have a decisive advantage: Not only is the decomposed polymer matrix recovered, but also the often expensive reinforcing fibers. Due to the limited size of the components, the fibers are no longer in the form of continuous fibers, but there are a large number of applications in which fibers in the length range up to a few centimeters are used.

Professor Alexander Böker, Head of Fraunhofer IAP explains: “This recycling process is of particular interest to companies because the matrix material can also be recycled on an industrial scale in order to synthesize sufficient quantities of new 'recycling thermosets' from it. With the Fraunhofer Pilot Plant Center for Polymer Synthesis and Processing PAZ - a joint initiative of the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam-Golm and for the microstructure of materials and systems IMWS in Halle / Saale - we have the opportunity to produce these resins in industry-relevant quantities to manufacture. "

photo: Defective aircraft components made of carbon fiber reinforced plastics could soon be repaired or recycled easily and inexpensively. © mev-Verlag

Visit us at JEC World!
JEC World 2016 | March 8-10, 2016, Paris (F) |
Joint stand of Carbon Composites e.V., Hall 5a, Stand D52
Exhibition center: Paris Nord Villepinte Exhibition Center |
Address: CD 40, ZAC Paris Nord 2, 93420 Villepinte, France

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The Fraunhofer Institute for Applied Polymer Research IAP

The Fraunhofer IAP in Potsdam-Golm specializes in the research and development of polymer applications. It supports companies and partners in the tailor-made development and optimization of innovative and sustainable materials, process aids and processes. In addition to the environmentally friendly, economical production and processing of polymers on a laboratory and pilot plant scale, the institute also offers the characterization of polymers. Synthetic polymers based on petroleum are just as much a focus of the work as biopolymers and bio-based polymers made from renewable raw materials. The fields of application are diverse: They range from biotechnology, medicine, pharmacy and cosmetics to electronics and optics to applications in packaging, environmental and wastewater technology or the aviation, automotive, paper, construction and paint industries. | Head of Institute: Prof. Dr. Alexander Böker