This reversible glue puts a screw in manufacturing

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Sonic boom? A new high-tech glue "unscrews" when exposed to a frequency.

Glues have been the cornerstone of linear mass production. Different materials can be easily combined for the huge variety of performance demands in our everyday stuff. But the same glues are a circular economy nightmare. They are a major obstacle when it comes to opening up products to salvage components, or for separating materials to create pure streams and achieve proper recycling.

Circular economy initiatives in the built environment  for example by BAM or Arup  also have encountered this hurdle. In response, some developers have started building with "dry connections." Different building materials such as wood, varieties of plastic and concrete can be easily recovered if only screws are used. It’s a great solution, but not easy to implement in products such as packaging, carpet, mattresses and alike.

So what about a glue that works like a screw? That’s the idea behind the DSM-Niaga joint-venture. Deploying this solution starts off in the same way, as the glue does what other glues do, holding layers together for the lifetime of the product. What is different, however, is that this glue "unclicks" when exposed to a signal after use. This "screw glue" enables the recovery of pure materials after use, and thereby increases the business case for recycling.

DSM-Niaga used the glue in carpets first. Start-up Niaga ("again" spelled backwards) was motivated by the giant volumes of carpet wasted globally. Even though this is a giant waste stream, the complex combination of materials used today, including adhesives, makes carpet economically uninteresting to recycle. Together with DSM, Niaga tried to redesign carpet from scratch.

The joint venture's objective was to make carpets fully recyclable back into a carpet, without compromising on price and quality. This objective was met after using a straightforward redesign strategy:

1. Use the lowest possible range of materials.

2. Use only materials with scientific proof on their recyclability and material health.

3. All materials should be easily recovered in their pure form after use.

Niaga first reduced today’s diversity of materials in carpets to only two materials, without compromising on quality. Then they applied this reversible glue to marry the two material layers together. As the adhesive is made from polyester, just like one of the main two ingredients, no additional material complexity was added here either. After use, the two materials can be decoupled in a split second, for full carpet-to-carpet recycling.

To the companies’ surprise, the simple materials set improved the performance far beyond recycling at the end of use. The new design also meant easier installation, improved fire resistance and stain resistance, strong weight reduction and 90 percent energy reduction in production. Today, the Niaga Technology is offered to carpet manufacturing companies globally, and in the U.S. the carpet is already available in shops.

The redesign team of DSM-Niaga is looking for other products to redesign, using the same philosophy and reversible adhesive. In November, it announced a collaboration with mattresses firm Royal Auping, to jointly redesign mattresses for closed-loop recycling. Together with carpet and diapers, mattresses are among the top five landfill items in many countries around the world.

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