Plastics have become widespread in their use with the majority of plastic being single-use, thus, leading to vast amounts of plastic produced yearly of which the waste gets landfilled or incinerated, polluted into the environment, or recycled. Recycling is not very effective for most plastics due to the inherent properties of durability and inertness. Recycling is divided into two categories, the first being physical which is often seen as a downgrade of the plastic compared to virgin material. The other category of chemical recycling allows for a pathway to avoid downgrading but is often energy intensive. Mechanochemistry (MC) refers to chemical reactions induced by mechanical energy at ambient temperatures. MC combines the best of both physical and chemical aspects of plastics recycling and avoids some of the drawbacks of individual methods. Mechanochemical reactions are often solid-state, do not require solvents, and are less energy intensive. In this work, polyethylene, (MW=4000 da) was degraded by MC reactions catalyzed with various zeolites (i.e., FAU and MFI). MC reactions were conducted in an oxygenated environment below 100°C for 12h using a planetary ball mill (PM-400) with stainless-steel jars containing grinding balls, polyethylene, and the catalyst. Thermogravimetric Analysis (TGA) was measured on the product residue and revealed the product degraded faster and at a lower temperature than the reference polyethylene, and <sup>1</sup>H, <sup>13</sup>C, and HSQC-NMR showed the presence of olefinic peaks. This low temperature, energy efficient process demonstrates that polymers can be successfully degraded to lower MW residues containing olefinic functional group. This reveals the effectiveness of MC in degrading polymers into smaller constituent building blocks, including olefins and alkanes, thus paving way for greener and energy efficient solutions to breakdown polymers into monomers.

Mechanochemical degradation of polyethylene to olefin containing residues

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