Technological watch

Recycled polyethylene terephthalate (rPET) honeycomb is now commercially ready and available to license from EconCore. The company successfully conducted two years of research, learning how to optimally process the reusable resource-based polymer into its continuously produced honeycomb core.rPET honeycomb sandwich panel outperforms PP honeycombs in terms of temperature and strength performance. Image courtesy of Econcore.The benefit is a substantial fall in CO2, along with the already established CO2 reductions from the honeycomb technology in many transportation applications, due to the fuel and energy savings during the in-service use of lower weight products.  

Recycled PET honeycomb cores, with the widespread availability of collected plastic, including bottle grade rPET flakes, offers excellent potential using an eco-alternative core material. It also has superior temperature resistance and mechanical properties compared to conventional thermoplastic core materials.

The company’s rPET honeycomb core is typically made from more than 95% recycled PET from a variety of sources such as bottles and food packaging. It is a cost-effective solution as it does not require much pre-production processing to achieve stable, temperature and strength performance outperforming PP honeycombs.

Wouter Winant, technical manager at EconCore said: “Our technology is very flexible and has proven to work with many thermoplastics already. Adapting the technology to successfully use PET and rPET honeycomb is another great step forward. By adjusting the content of additives or fillers, we can optimize the performance characteristics.

“One key aspect of the development journey was the optimization of the processing methodology and adapting the equipment in order to increase the efficiency of the continuous honeycomb production process. We worked closely with our partners at MEAF who developed and adapted the machinery to achieve the results we were looking for.” MEAF designs, develops and builds extrusion machines for the global packaging and plastics processing industry, based in the Netherlands.

Ardjan Houtekamer, technical director at MEAF said: “We worked closely with EconCore’s technical team over a number of months to refine the machine to achieve an optimum production speed. With EconCore’s high throughputs, extruding up to 1,200 kg per hour while using only 0.20 kWh per kg, the sheet extruders we developed are currently among the most efficient in the market.”

There are many applications that stand to benefit from using a honeycomb core with better heat and strength properties than a PP honeycomb.

Winant said: “That’s a really attractive proposition to licensees of our technology. When you consider the global problem of plastic waste and the urgent need to take better care of the environment, using a honeycomb core based on recycled PET could, without a doubt, be a sustainable solution for markets of large volume production, including automotive, general ground transportation, packaging and furniture.”

The ThermHex technology plays an essential role in enabling the use of honeycomb materials in cost sensitive applications. Applications include the sidewalls of delivery trucks and trailers, vehicle interiors such as parcel shelves, headliners, boot/trunk floors and other interior panels. It can also be used for concrete casting molds and façade panels in the commercial construction and building sector. There are countless other potential applications that could take advantage of this technology that would reduce costs and weight while maintaining or increasing strength.

PET is one of the most widely used plastics in the world, particularly with bottles and food packaging. The bottle industry now re-uses transparent bottles, but that leaves an enormous amount of coloured waste PET globally. For some products, how it looks is important. With EconCore’s technology, aesthetic considerations of the inner honeycomb core of sandwich panels are unimportant.

Winant said: “Everyone at EconCore is hugely supportive of finding ways to recycle and reuse plastic waste products. It is a massive global issue. EconCore can play a small role in solving part of that problem, through research and innovation, producing a cost efficient, better, stronger product, that we know will be attractive to many industry sectors.”

The rPET honeycomb cores from EconCore are set to be used in a project by Eindhoven University of Technology who will design and build a road legal car completely made from waste, recyclable and biodegradable material by June 2020. EconCore are a gold sponsor of the project and its product will be used for the chassis. The project is called Luca and is part of a project called TU/ecomotive.

While companies are now able to license the EconCore technology to produce honeycomb core sandwich panels and parts using rPET, the development work does not end there.

Winant concluded: “We will continue to push the boundaries, for more demanding applications. The research never ends, and we are constantly learning how to adapt our technology for lower volume, high-specification applications such as rail transport and aerospace where strength and low weight are important and CO2 reductions with materials from renewable resources are needed.”