Take a stroll through a grocery store and one thing is clear—almost everything, from meat and bread to produce and cookies—is packaged in some form of plastic. While those wrappers look simple, the plastic is much more sophisticated than it seems: Most of it is constructed from multiple layers, each with its own function—such as moisture-proofing, gas-permeability, oxygen-resistance or heat-tolerance.
While that makes the packaging great at preserving food, mixed plastic layers are incredibly difficult to recycle. Add in inks and dyes and recycling gets even more complicated. Developed by University of Wisconsin-Madison chemical engineers, a process called solvent-targeted recovery and precipitation, or STRAP, uses a solvent to dissolve the plastic in each layer, allowing them to recover plastic resins one by one.