R&D Focus
Move Towards Net Zero with Your Feet New Materials to Make Shoes Greener
ITRI’s eco-friendly shoe material significantly reduces the carbon emissions of shoe production.
Common plastics used in shoe production such as polyester (PET), thermoplastic polyurethane (TPU), and ethylene-vinyl acetate (EVA) are unrecyclable and responsible for substantial carbon emissions. To phase out these eco-unfriendly shoe materials, ITRI has developed a novel and low-carbon emission material called recycled thermoplastic polyester elastomer (rTPEE-G).
rTPEE-G consists of recycled polyester (rPET) extracted from PET bottle flakes and bio-based diamines. According to Wayne Wu, Technical Manager from ITRI’s Material and Chemical Research Laboratories, the new material cuts the carbon emissions of producing a pair of shoes from 13.6 kg CO2e to < 2 kg CO2e—a significant 80% decrease from those of conventional plastic shoes. This provides shoe makers with a promising material solution to meet their carbon reduction goals.
Conventional shoe manufacturers use different materials to produce upper, laces, midsole, and outsole of a shoe and thereby heterogeneous material poses an obstacle to footwear recyclability. rTPEE-G was developed to address this issue. This material alone can be made into these shoe parts to suit their needs without compromising its quality or performance. It acquires properties such as high rebound, high shock absorption, or anti-slip. Such versatility makes it easy to accommodate the designs of functional and comfortable sneakers.
ITRI’s rTPEE-G material can be used for different shoe parts.
To avoid using adhesives that hinder shoe dismantling, rTPEE-G enables the midsole and outsole, which account for 60% of a shoe, to be produced as one piece with a foam injection molding technique. As this new structure requires no other materials than rTPEE-G, discarded shoes at the end of their life cycle can be easily sorted and pulverized, and the recovered materials can be reproduced into shoe parts or even new sneakers, realizing the shoe-to-shoe, closed-loop recycling.
As numerous countries are committed to achieving net zero emissions by 2050, influential brands such as Nike and adidas have also been developing products made from recycled materials. By turning the nonrecyclable into recyclable, rTPEE-G gives new hope to the shoe industry by providing a solution that makes shoes more recyclable and more sustainably produced with less waste and a smaller carbon footprint.