Beneficial Use of Plastic Wastes

discarded old phones and keyboardsOver the past two decades, use of computers and other electronic devices has increased dramatically. Rapid changes in technology and a consumer desire for the latest gadgets have caused a similar increase in electronic waste (e-waste). In 2015, the United States generated over three million tons of e-waste. Less than half was recycled.

Metals and glass from e-waste are readily recyclable, but plastics from electronics pose a problem. Unlike water bottles and milk jugs, which are made of single polymers, plastics in electronics are often made from polymer blends. That means that they’re usually incinerated or sent to landfills because there are no safe or inexpensive ways to recycle them.

Researchers B.K. Sharma and Sriraam Chandrasekaran saw this challenge as an opportunity. Their research led them to develop a nontoxic, nondestructive and energy-efficient chemical solvent process to recover polymers from these more complex plastic blends.

The most efficient solvent methods used today involve a chemical called DCM, which releases carcinogenic vapors into the air at near-room-temperature conditions. These vapors contaminate the workspace and introduce the potential for release into the atmosphere.

The researchers’ process uses a solvent called NMP, which only releases vapors when heated to 180 degrees Celsius, far above the temperature needed to dissolve the polymers. Another advantage of this process is the ability to condense the solvent so that it can be reused multiple times.

The process leaves behind some residual polymer waste. The researchers can convert those remains into useable fuel oil by a thermochemical process called pyrolysis, which means they avoid sending these leftover plastics to landfills.

The team has successfully demonstrated this new solvent process with small quantities at the lab scale and has produced polymers with comparable quality to their virgin-material counterparts.

The next step will be to run the recycled polymers through a manufacturing process and test for quality. If they are successful with that process, they will begin a pilot-scale project.

This research was included in a report recently released by the Center for the Circular Economy, a project of Closed Loop Partners. The report surveys the current state of research focused on converting waste plastics into safe and high-quality materials, as well as the scale of opportunity for these technology providers to meet the demand.