By Ben
Coxworth
September 21, 2022
Facebook
Twitter
Flipboard
LinkedIn
Depending on how much simulated recycled plastic is present
within them, a series of plastic samples fluoresce in differing colors and
intensities (Photo credit: Adapted from ACS Sustainable Chemistry &
Engineering 2022
VIEW 1 IMAGES
First of all, why would companies falsely claim
that they were using recycled plastic? Well, for starters, doing so might gain
them some sales with eco-minded consumers. Additionally, they could avoid
paying taxes that some countries are imposing on plastic products which contain
little or no recycled plastic.
In order to thwart such deception, scientists at the
University of Manchester looked to a food-safe molecule known as 4,4,-bis(2-benzoxazolyl)
stilbene … or BBS, for short.
The researchers added small amounts of BBS to melted
high-density polyethylene (HDPE), which was subsequently mixed with virgin HDPE
resin in varying ratios. Their end result was a group of HPDE samples which contained
anywhere from 0 to 100% simulated recycled content.
When those samples were exposed to 365-nanometer
ultraviolet light, the BBS molecules within them reacted by fluorescing. It was
found that the intensity, duration and color of the fluorescence varied
according to the percentage of BBS-tagged HDPE within each sample.
Therefore, by measuring those parameters, it became
possible to accurately gauge how much of the simulated recycled plastic was
present in any one of the samples. The technology was also successfully tested
on plastics such as polypropylene and PET (polyethylene terephthalate), in
which it could quantify simulated recycled content as low as 10% by weight.
According to the scientists, the presence of BBS in
single-use plastic products doesn't adversely affect their quality or
appearance. It is hoped that ultimately, manufacturers could add the molecule
to virgin plastics as they're being recycled, so their content could
subsequently be measured in other products made from them.
A paper on the research was recently published in the
journal ACS Sustainable Chemistry & Engineering.
Source: American
Chemical Society via EurekAlert