Page 32 - ETP-April-May2020

RESEARCH

New age recycling

A team of researchers has discovered a new way to recycle a versatile plastic material,
called polyurethanes, which could prevent the material from becoming waste.

esearchers at the Uni- very common form for polyurethane
versity of Minnesota products.
are part of a national In this new study, research-
Rteam in the Center for ers from the University of Minne-
Sustainable Polymers that has sota and Northwestern University
found a better way to recycle a ground up polyurethane foam or
versatile plastic material, called film and then mixed the particles in
polyurethanes, which could a catalyst solution. After drying, the
prevent the material from be- particles were compression molded
coming waste. | Researchers from the University of Minnesota and to form new films. Compression
In the past, a few meth- Northwestern University have improved the recycling molded films formed good-quality
ods have attempted to recycle process of polyurethane through the development of a products, but compression molded
polyurethane waste, but these twin-screw extrusion process that improved mixing and air foam produced cracked and inho-
techniques result in a material removal in foams. Credit: Sheppard et al., ACS Central Science mogeneous materials.
of lower quality. Now, research- The researchers solved this
ers have found a way to recycle used plied to help solve environmental problem by developing a twin-screw
polyurethanes into equivalent or problems.” extrusion process that improved
even higher quality material using Conventional polyurethanes mixing and air removal in recycled
an innovative method. Their find- can’t be simply recycled by heat- foams, compared to the compres-
ings are reported in the journal ACS ing because the material consists of sion molding approach. They say
Central Science, published by the polymer networks held together by this new method could be used for
American Chemical Society. strong chemical bonds that don’t continuous recycling of the large
“We are quite excited about flow when heated. Instead, polyure- amounts of polyurethanes waste
this new research from the Center thanes can only be downcycled into currently in landfills and newly pro-
for Sustainable Polymers because of less useful materials using either me- duced.
the tremendous potential for recy- chanical methods or chemical recy- “The extrusion process removes
cling of polyurethane materials that cling. Other past methods have made air simultaneously as the catalyst
are typically considered as waste,” innovative types of polyurethanes enables the polyurethane to flow like
said Marc Hillmyer, director of the with cross-links that can be broken a liquid,” said Christopher Ellison,
Center for Sustainable Polymers and reformed, allowing it to be recy- a University of Minnesota chemical
based at the University of Min- cled. But this approach requires the engineering and materials science
nesota and a chemistry professor industry to commercialize new start- professor and one of the senior au-
The Economic Times POLYMERS | April-May 2020
at the University of Minnesota. “It ing materials, and it wouldn’t ad- thors of the study. “This reactive pro-
also demonstrates how the powerful dress the issue of conventional waste cess is similar to those already used
combination of polymer chemistry lingering in landfills. These methods in the plastics industry for other pur-
and polymer processing can be ap- also haven’t been tested on foams, a poses meaning the technology could
have impact quickly.”
“THE EXTRUSION PROCESS REMOVES AIR The research was primarily fund-
SIMULTANEOUSLY AS THE CATALYST ENABLES ed by the National Science Founda-
tion through the Center for Sustain-
THE POLYURETHANE TO FLOW LIKE A LIQUID. able Polymers. The study’s authors
THIS REACTIVE PROCESS IS SIMILAR TO THOSE from the University of Minnesota
ALREADY USED IN THE PLASTICS INDUSTRY FOR Department of Chemical Engineer-
OTHER PURPOSES MEANING THE TECHNOLOGY ing and Materials Science, authors
COULD HAVE IMPACT QUICKLY.” from Northwestern University De-
Christopher Ellison, a University of Minnesota chemical partment of Chemistry.
engineering and materials science professor.
Source: University of Minnesota

32