Issue 06/2021

Materials
Fill the gap, not the landfill
Governments and institutions have been scrambling
to rectify the global environmental disaster caused
by the accumulation of plastic waste. This plastic
waste comes in macroscopic forms such as bottles, plastic
bags, and polyester clothing. In the best-case scenario, it is
regulated and dumped into overcrowded landfills or in the
worst case, it escapes into the open environment as litter
directly endangering the health and safety of wildlife and
local populations [1]. Alarmingly an even more insidious
type of plastic, ‘microplastic’, or plastic waste so small it
is invisible to the eye, has been making headlines as it can
be found in the water, soil, and even inside of our bodies [1].
The steps being taken to address this issue focus
on banning specific single-use plastic items or their
substitution with more sustainable alternatives (reusable,
recyclable, or compostable). This is part of an overall shift
from a linear economy to a circular economy. To accelerate
this change, governments have passed their own single-use
plastics bans or have committed themselves to initiatives
such as the New Plastics Economy, Global Commitment led
by the Ellen Macarthur Foundation (EMF) [2].
The goal is to ‘build a circular economy around plastics’
by initially setting strict goals around certain single-use
plastic items for 2025. With these measures in place there
is an incentive for building a future where plastics are either
replaced and or are fully circular. In the meantime, there are
still large gaps that need to be filled by addressing singleuse-items
that fall outside of traditional packaging or
consumer products. Personal protective equipment, sterile
items, and chemically contaminated consumables are
items that are not easily substituted with other materials as
these applications require high-performance and durability
that only plastics can currently provide. Additionally, these
items have recyclability challenges due to contamination or
are used in remote environments (such as for agricultural
applications) where they cannot be efficiently collected [3].
These items are usually landfilled or incinerated, both of
which do not fall under the Ellen Macarthur Foundation’s
definition of circular [2]. The current COVID-19 pandemic
has only exacerbated this type of waste due to the significant
increase of personal protective equipment (PPE) and sterile
consumables. Sources have cited that over four million
tonnes of polypropylene waste from PPE have been disposed
of over the course of the pandemic and will continue to grow
[3]. These hard to remediate items are important and will
not disappear.
A solution is to develop innovative materials and circular
product design. Biodegradable and compostable plastics
are viable options to tackle this problem, as they have
the potential to match the performance needed for these
applications [4]. On the other hand, some of these plastics
display incomplete degradation ultimately leading to
microplastics. To elevate degradable plastics into truly
sustainable and viable alternatives major improvements
and innovations are needed.
Scientists have been designing materials that allow rapid
degradation – much more efficient than their traditional
counterparts. In addition, the onset of degradation can
be controlled or triggered. In recent years, triggered
degradation plastics that utilise hydrolytic enzymes
have created attention in the media due to their speed of
degradation and broad applicability. The idea of enzymes
that can degrade plastic, particularly polyesters, is not new
as the entire concept of microbial biodegradation hinges on
this process.
Scientists managed to remove the microbe from the
picture by directly mixing the enzymatic material with the
plastic – a sort of trojan horse plastic composite. Under the
right conditions, degradation happens from the inside out for
these novel plastics. Scientists around the world are working
on developing and optimizing these materials. At Scion, a
Crown Research Institute in New Zealand, researchers
have been exploring how to design and manufacture these
materials using solvent-free thermoplastic processing
techniques. Being able to thermally process them is key to
ensuring their viability commercially.
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26 bioplastics MAGAZINE [06/21] Vol. 16