A new recycling strategy for airbag waste

Abstract Multi-layer materials are often used in technical parts to achieve certain properties of products and thus adapt their property profile to the respective application. However, a major challenge of plastics recycling is the separation of the various polymer components. One example for this are airbags. Airbags consist primarily of polyamide 6.6 (PA66) fibers and an additional silicone coating. During recycling, the silicone layer cannot be mechanically separated from the synthetic fiber. Therefore, the silicone particles remain in the recyclate with a poor bonding to the PA66 matrix. In turn, this can lead to poor mechanical properties of the recycled material and early material failure due to interface detachment. In this work, a new recycling strategy for the functional integration of silicone particles is demonstrated using the example of airbag waste. A reactive compounding of the waste with special coupling agents in a twin-screw extruder was conducted to achieve adhesion or coupling between the silicone particles and the PA66 matrix. Rheological tests confirmed the formation of physical or chemical bonds by adding the coupling agent, respectively. Nano-IR-AFM analyses demonstrated the improved integration of the silicone particles into the PA66 and the reduction of cavities in the compound. Mechanical characterization showed the increase in notched impact strength and elongation at break by almost double, which means that a higher plastic deformation is possible. These results show that coupling of the silicone particles to the PA66 matrix can be achieved by the use of coupling agents. The silicone particles no longer act merely as a filler, but as a functional additive or an impact modifier.