Recycling of Airbags Using Hydrothermal Treatment and Characterization of the Separated PA66

Composite material products made of two or more materials are widely used worldwide. However, recycling these materials is not widespread as separating the individual components is challenging. Therefore, a technology to effectively separate materials is essential to enhance recycling rates and establish a sustainable recycling industry. In this study, we aimed to separate common polymer materials from the multimaterial products using an eco-friendly hydrothermal technique that utilizes only water, leveraging the melting point depression of polymers in water. For instance, airbags as multimaterial products are commonly installed as safety devices in automobiles. Most airbags are typically composed of a polyamide 66 (PA66) base fabric coated with silicone to improve airtightness. As it is challenging to separate PA66 and silicone, most airbags are currently being discarded. This study revealed that PA66 could be separated by treating the airbags at temperatures exceeding 200 °C. Additionally, the separated PA66 retained its melting point, indicating that it could be separated without decomposing into monomers─unlike common chemical recycling methods. These findings suggest possibilities for mechanical recycling, using the difference in melting points to separate the individual components in their polymeric state from various combinations of composites.