Selective Recovery of Ethylene Vinyl Alcohol from K-Cups

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Plastics

Background:

• Multilayer plastics in food packaging generate significant plastic waste due to difficulties in reclaiming valuable barrier polymers.
• Current thermomechanical recycling methods dilute high-value barrier polymers in commodity streams, negatively impacting recycled material properties.
• Effective separation of barrier polymers like ethylene vinyl alcohol (EVOH) from polyolefins is crucial for sustainable plastic recycling.

Purpose of the Study:

• To investigate the use of dimethyl sulfoxide (DMSO) as a solvent for separating ethylene vinyl alcohol (EVOH) from polyolefin-based food packaging.
• To assess the feasibility of a chemical extraction strategy for recovering valuable barrier polymers from multilayer plastic waste.

Main Methods:

• Collection of single-use coffee containers (K-Cups) composed of multilayer plastics.
• Immersion of collected containers in hot dimethyl sulfoxide (DMSO).
• Analysis of the thermal, spectroscopic, and rheological properties of the extracted EVOH.

Main Results:

• Dimethyl sulfoxide (DMSO) selectively dissolved the ethylene vinyl alcohol (EVOH) barrier layer while leaving polyolefin layers intact.
• The extracted EVOH exhibited comparable thermal and spectroscopic properties to virgin EVOH.
• Rheological properties of the extracted EVOH differed from virgin polymers, indicating potential for tailored applications.

Conclusions:

• Dimethyl sulfoxide (DMSO) offers a viable and relatively simple chemical method for separating high-value EVOH barrier polymers from polyolefin waste.
• This extraction technique facilitates the recovery of valuable polymers, contributing to improved plastic waste management and circular economy principles.
• The findings support the development of advanced recycling strategies for multilayer plastic packaging.