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| J. Mirian Diop, a graduate student with Northwestern University’s Torkelson’s Research Group, adjusts the construction of a screw for the lab’s “extruder,” a gadget that combines polymers molecularly. Diop left an industrial chemical engineering career to pursue environmentally beneficial research. (Jessica Krinke/MEDILL) |
Northwestern University’s Torkelson Research Group has big plans for those tiny grains. Diop and her colleagues think that someday the work done here will change the way the world produces and recycles much of its everyday plastic products.
After each tweak of the mixture, Diop sets up again for another three-hour test beneath the lab’s florescent lights and concrete walls lined with machinery parts and trays of various granulated plastics.
Right now, the conventional way industry creates plastics is to melt down the specific polymers (science for plastic) needed and blend them with dyes until the mixture is the desired color and consistency.
Plastic is so ubiquitous in the everyday life of global consumers that this process has been repeated countless times over the past half century. But Diop explains that there’s a better way. “Polymers in the melt state require lots of mixing and [stretching] and you have to keep adding and adding dye until you see results. Solid state requires less [coloring] to get the same look,” she said.
The process of handling plastics in a melted, liquid state may be widely used but when polymers combine in the dry, solid state they do so on the molecular level – producing more evenly-distributed results. These plastics then require less dye to color (a step in the process studied by Torkelson group member and Diop's co-researcher, Philip Brunner) and less heat and energy to produce thus they’re cheaper and more environmentally friendly overall.
To concoct her plastics in a dry state, Diop feeds the polymer grains through the lab’s “extruder” – a device they’ve frankensteined to suit their purpose. The grains pass between two lengthy screws that apply enough pressure to combine them molecularly. The team is then charged with testing different polymer combinations and analyzing the results.
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| The lab’s extruder. The screws (pictured above) are inserted into the center holes and polymer grains are then fed through to combine them. The group has made this “melt extruder” into just a plain “extruder” by fitting it with coolant tubes to keep the mixture in a solid state. (Jessica Krinke/MEDILL) |
Diop laughs and slaps her hand on the dated-looking tangle of machinery, “Sometimes this thing can be so frustrating, but I love it. Last week it broke down and we were trying to fix it for days. Then the repair guy figured out what was wrong in three hours.”
By perfecting a process that can be standardized for industry at large, the Torkelson Group hopes to revolutionize plastic production for the better. The constant testing should also root out ways that different polymers combine to discover new substances and streamline recycling – breakthroughs that Diop dreams of someday bringing back to her native Ghana and the rest of the developing African continent. “People think that we don’t need [recycling] there yet, but I don’t think we should have to wait until it’s a problem.”
When you recycle a water bottle, the cap must be separated from the bottle because the different types of plastic can’t be melted together – typically requiring hiring someone to do this by hand. But if a new kind of plastic can be developed with the strength and flexibility of both the cap and the bottle, the process becomes that much cheaper and widely applicable.
The Torkelson Group has a couple patents in the works for the solid state process and continues to work daily on new combinations and their processes.
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NOTES: This was not published only because it was an exercise in translating science-speak into prose and was on a class assignment schedule and not a newsroom one. But it should have been since this was such a pleasure to report.
Who says recycling won't save the world?
