(270c) Polyolefin Dissolution Fundamentals and Applications in Dissolution/Precipitation Separation of Polyolefins Via Cycling of Switchable Solvents

Polyolefins constitute about half of the 1 trillion pounds annual global plastics production, but less than 10% are recycled and the rest landfilled or incinerated. Dissolution/precipitation is a method that can increase polyolefin recycling, however information on polyolefin dissolution is lacking. Also lacking are solvents that are both selective for polyolefins and can induce their precipitation.

This presentation addresses the mechanism of semicrystalline polyolefin dissolution as revealed through joint in situ infrared spectroscopy experiments [DOI: 10.1002/pol.20250207] and diffusion kinetics modeling [DOI: 10.1002/aic.15615].

The presentation also highlights the application for polyolefin recovery of switchable hydrophilicity solvents (SHS) that can cycle between a form that dissolves the target polymer and a form that does not, hence facilitating closed-loop solvent cycling.

The insights obtained from these studies facilitate the design of efficient solvent systems and processing conditions for the molecular recycling of polyolefins via dissolution/precipitation. Through this method, specific polymer types can be separated from mixtures or blends, purified from additives, and recovered for further processing, without negatively affecting the properties of the original polymers, and with minimal greenhouse gas (GHG) emissions.