May/June 2022 - 15

TECHNOLOGY
and the method of packing them would determine the
quality of the end panel.
" Nut shells are actually a pretty good waste material to
use because they're pretty clean, " said Yadama.
Hazelnut shells fall in a line of reused materials, such
as wood fibers, natural fiber fabrics like those from used
jute coffee bags (heavy duty burlap sacks), and sunflower
hulls. Even though various materials aren't mixed together
in a single layer, there have been projects and experiments
where they are layered - each material infused in resin, and
then those layers assembled to construct a thicker panel.
Another challenge, however, is that these resins are
particularly difficult to bond to one another once the
material has set.
" We wanted to demonstrate that we could bond them
together using a particular technique. So, we made them
separately and bonded them, " said Yadama. " It's a layered
structure, so to speak. "
Hazelnut shells lying on the bottom face
of the metal mold during packing.
For instance, cheaper and less visually attractive materials
can make up the core of the panel, with the more attractive
materials used as the top or outside-facing layers.
The science of waste reduction
Fiber volume fraction:
The ratio of fibers present in
the total volume of the layer
The craft of assembly
WSU receives already processed and cleaned nut shells,
and uses a recyclable resin in a resin-transfer molding
process. After determining the right atmospheric conditions
for the forming process, the resin is pulled into the hazelnut
shells via vacuum.
But it isn't just about using nut waste materials to create
something new. It's also about making that new object an
environmentally sensible product by using a high fiber
volume fraction.
" There are a lot of companies and industries that make
similar kinds of panels from other fibers, " said Chanda. " But
the fiber volume fraction is less, roughly around 15-20%. Our
goal is to go higher to at least 50-60% fiber volume fraction,
so that there is more fiber and less resin. "
Increasing the fiber volume fraction has happened on
a smaller scale, and the challenge is now in scaling up.
These techniques would automatically lower the cost of
production - less resin, less cost.
Included in this process is finding the balance among
materials that each have their own unique mechanical
properties. Particle size of the shells, their moisture content,
It's no secret that nut processing facilities produce a lot
of waste materials in the form of hulls and shells. While
there is a greater shift happening in using those materials in
other ways, a great deal of it still goes to waste.
And it's not that it can't be used, said Yadama, but an effect
of expensive distribution of the materials once collected due
to low bulk density. Simply put, it's expensive to transport.
But once the collection issue is sorted and the added value
of style decided, there is the bonus of carbon sequestration.
" We have more of a sustainable consciousness now -
reduce waste, store carbon. All of these materials are full
of carbon, " explained Yadama. " If you don't burn it, and
it doesn't disintegrate and release carbon back into the
atmosphere, and you store it further for a longer time,
that's a good thing. "
These kinds of strategies mean there's more potential for
these kinds of products. The challenge now is within the
resin itself. Resin isn't exactly a bio-based material, and,
depending on the type of resin, is not generally recyclable.
The team at the lab is looking into this and working
towards this goal as well.
" We have to think about the manufacturing process
and what kinds of properties the panel would have. The
nut shells and fibers are not compatible with the types of
resins that are produced. They don't chemically bond with
each other, and if they don't chemically bond, it affects the
mechanical properties and so forth, " said Yadama.
The different panels are tested for tensile strength, such
as bending and impact, as well as sustainable loads and life
cycles. Panels can be subjected to different environmental
conditions - such as to mimic cold, dry, humid and hot
regions of the globe - and different load conditions to see if
the panel is affected by the conditions and how.
Approximately 50 lbs. of hazelnut shells are used to make
a commercial-sized 4 ft. x 8 ft. x .5 in. panel.
NATIONALNUTGROWER.COM 15
http://www.NATIONALNUTGROWER.COM
May/June 2022

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