Canadian Plastics

Biodegradable shoe soles are on their way

Canadian Plastics   

Materials Research & Development

A Swiss researcher is developing a process that could one day be used to make plastic shoe soles, yoga mats, and other foamed products from organic waste.

Photo Credit: eshana_blue/Adobe Stock

A scientist at ETH Zurich public research university in Zurich, Switzerland is developing a method that will allow natural agricultural waste to be processed into biodegradable foamed plastics for use in any product that requires the elastic, cushioning property provided by foam materials, from automotive parts to shoe soles, toys, yoga mats, packaging or mattresses.

The existing problem to be tackled is that, at present, these materials still tend to be made from fossil resources, with the addition of synthetic materials. The resulting products have a huge environmental impact, as it takes decades or even centuries for the plastics to break down into microparticles, and they will never degrade entirely. Furthermore, it’s usually a real challenge to recycle products made of foamed plastic.

Developed by ETH Pioneer Fellow Zuzana Sediva, the new solution involves the use of a novel propellant that’s added during the manufacturing process to enable the biomass to foam at lower temperatures. The bio-propellant is completely green – unlike the synthetic additives used in the production of foamed plastics – and is based on a mixture of gas and water.

If foam materials made out of organic waste are to achieve a high level of elasticity, a precise “recipe” must be followed that includes the specially designed propellant, an organic waste-​based formulation, and a specific manufacturing process.


Sediva has filed a patent on the technology, in partnership with ETH, and is now refining the method for industrial use. Manufacturing the new propellant in large quantities will not be a problem. “We can make up to 60, perhaps even 100 liters of foam an hour,” Sediva said, and she intends to prove this in the next few months. This would fulfil one of the requirements for bioplastic to become a success not only in the laboratory, but also on the market.

Another advantage of Sediva’s method is its compatibility with traditional processes used to manufacture foamed plastics, so potential customers do not require additional infrastructure.

Prospective clients will depend on who is willing to be involved in pilot projects. Sediva is currently looking for industry partners. “I think packaging would be a good entry point,” she said, since foamed materials are used to protect products, or for the design process. Later, the shoe industry could be another potential client, she added.

Source: ETH Zurich


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