Page 54 - Plastics News February 2022

TECHNoLoGY

Researchers Find Hundreds Of Various Chinese Researchers

Chemicals In Reusable Plastic Bottles Develop New Method
For The Production Of

Protein-Based Plastics

research team has now introduced
A a new method for the production
of protein-based plastics that are
easily processable, biodegradable,
and biocompatible, as well as having
favorable mechanical properties. A
team led by Jingjing Li and Yawei
Liu (Chinese Academy of Sciences,
Changchun, China), as well as Bo Wei
(First Medical Center of PLA General
Hospital) have now introduced novel
bioplastics with properties that can be
tailored according to need. To do this
they developed two lysine-rich proteins
and produced them in bacterial cultures:
esearchers at the University of says Jan H. Christensen, Professor of "ELP" is a polypeptide similar to the
RCopenhagen have found several Environmental Analytical Chemistry connective tissue protein elastin. It does
hundred different chemical substances at the University of Copenhagen's not have defined folding, which leads to
in tap water stored in reusable plastic Department of Plant and Environmental toughness and elasticity. "SRT" consists
bottles. Several of these substances are Sciences. rofessor Christensen and fellow
potentially harmful to human health. researcher Selina Tisler detected more
According to the chemists behind than 400 different substances from the
the study, there is a need for better bottle plastic and over 3,500 substances
regulation and manufacturing standards derived from dishwasher soap. A large
for manufacturers. Two chemists from portion of these are unknown substances
the University of Copenhagen have that the researchers have yet to identify.
studied which chemical substances are But even of the identified chemicals,
released into liquids by popular types the toxicity of at least 70 % remains
of soft plastic reusable bottles. The unknown. Photo-initiators are among the
results were quite a surprise. Have you toxic substances in the water which worry
ever experienced the strange taste of the researchers. These are known to have
water after it has been in a reusable potentially harmful effects on health
plastic bottle for a while? It appears in organisms, such as being endocrine of ELP plus crystalline segments of a
that there is a solid, yet worrying reason disruptors and carcinogens. Furthermore, squid protein with a β-sheet structure.
for this. "We were taken aback by the the researchers found a variety of plastic ELP (or SRT) is crosslinked with a
large amount of chemical substances softeners, antioxidants and release agents polyethylene glycol (PEG) derivative
we found in water after 24 hours in used in the manufacture of the plastic, by way of its lysine amino side-groups.
the bottles. There were hundreds of as well as Diethyltoluamide (DEET), (PEG is used in pharmaceuticals, among
substances in the water -- including commonly known as the active substance other things.) If the crosslinking occurs
substances never before found in plastic, in mosquito spray. The most toxic in water, the material can then simply be
as well as substances that are potentially substances that we identified actually dried in a mold resulting in a tough,
harmful to health. After a dishwasher came after the bottle had been in the transparent, solvent-resistant bioplastic.
cycle, there were several thousand," dishwasher "

54 PLASTICS NEWS FEBRUARY 2022