now has 349 U.S. cities, counties and states with regulation either banning or taxing plastic bags alone. The plastics
industry is responding, as we always do, with technology.
The industry is going several different directions and trying a
variety of different solutions to reduce the impact of plastic on
the planet. Industry efforts to reduce the impact fall into three
broad categories: use less, recycle more and reduce the impact
of what escapes to the environment.
Use less plastic
Catalyst scientists, materials scientists and packaging
designers continue to push boundaries, improving the
performance to allow more to be done with less. Today’s
resins are much stronger than previous generation materials,
letting a thinner film do the same job that would have
required a thicker film in the past. In many applications,
resin use is cut substantially. Water bottles are one place
where the reduction in resin used is obvious. Today’s bottles
are substantially thinner, requiring far less resin, more than
50 percent less than previous generations.
Advances in polymers frequently go unnoticed. There are
exceptions, such as R&D 100 Award winning INNATE™
Precision Packaging Resin. This bimodal polyethylene
gives stiff, tough and clear films with improved mechanical
properties. Compared to traditional polyethylenes, it achieves
up to 80 percent less haze, twice the impact strength, twice
three times the tensile strength. Down-gaging, using thinner
films, with INNATE™ or other high performance polymers
reduces overall plastic use.
Replacement reduces packaging used. A trip to any grocery
store illustrates how flexible packaging is replacing thicker,
heavier rigid packaging for many products. Wine, oil, paint,
ketchup, nuts, and soap are just some examples where packaging is shifting away from ridged to flexible. Material replacement leads to significant reduction in material use, and, with it,
reduction of fuel used to transport goods both through reduced
weight and more efficient packing of trucks.
There are two major paths to recycling, mechanical and
chemical. Mechanical recycling is reprocessing scrap material,
using the scrap instead of or added to virgin resin. Most resins
degrade slightly during processing. Use of post-consumer
material requires sorting and cleaning. Separation of mixed
polymer streams is challenging. Contamination concerns loom
large, limiting recycled polymer in food contact applications.
Mechanical recycling of consumer material back to original
or higher value use largely remains an aspirational goal,
with much recycled material going to lower-value use.
Chemical recycling describes methods that converts plastics to
monomers, enabling the production of virgin polymer again
without fear of contamination. Chemical recycling recycles
produces material suitable for original or higher value use.
Research to improve mechanical recycling continues to
make great strides. The 2017 Newcomb Cleveland Prize was
awarded for work synthesis of multi-block copolymers with
tailorable blocks that serve as compatibilizers for blends of
polyethylene and polypropylene. While very similar, they are
immiscible in a melt and limit recycling. A recognized issue,
there are a variety of products already on the market. Exxon-Mobil produces Vistamaxx™ performance polymers and Dow
produces INTUNE™ Olefin Block Copolymers, to name
two. INTUNE™ Olefin Block Copolymers are made using
novel chain-shuttling catalysis that overcomes limitations of
the living polymerization recognized with the Newcomb prize,
polymerizing ethylene and propylene in a robust industrial
process. Research will certainly continue to refine and improve
compatibilizers added to facilitate recycling.
Making materials more easily recycled also is an area of
active innovation. Compatibilzers can be added into the virgin
material making it better for recycling. Most users are unaware
of the technical complexity contained in the packaging they
encounter. Many packages are made up of multiple layers,
with layers for structure, for barrier and for aesthetics. Multiple
materials complicate recycling so efforts to provide more
functionality from the same base resins continue to be ripe for
innovation. Dow introduced RecycleReady™ Technology that
uses a range of polyethylene resins to replace difficult to recycle
resins in multilayer structures, improving recyclability.
The three options for reducing the environmental
impact of plastic, use less, recycle more and reduce
the environmental impact. Credit: Dow Chemical