December 12, 2012 | ||||||||
Increased efficiency and operations at Skärblacka recovery section | ||||||||
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Cellulose Nanomaterials - Come and Get it! Cellulose constitutes the
most abundant renewable polymer resource available today, and natural
cellulose based materials (wood, bagasse, cotton, linen, etc.) have been
used by our society as engineering materials for thousands of years. As
a chemical raw material, it has been used in the form of fibers or derivatives
for nearly 150 years for a wide spectrum of products and materials in
daily life.
Although cellulose crystals have been known for over 50 years, what
has not been known until relatively recently is that these rod-like
crystals are defect free and incredibly strong. Papermakers have been
taking advantage of this inherent material in pulp for centuries. But
now other researchers are discovering the unique and powerful properties
of this renewable, sustainable material.
Potential applications include, but certainly are not limited to, barrier
films, antimicrobial films, transparent films, flexible displays, reinforcing
for polymer composites, biomedical implants, pharmaceuticals, drug delivery,
fibers and textiles, templates for electronic components, separation
membranes, batteries, super capacitors, electroactive polymers, and
many others.
Samples for Research & Product Development In late July 2012, the U.S. Forest Service Forest Products Laboratory
(FPL) celebrated the opening of their $1.7 million pilot plant in Madison,
Wisconsin. This investment allows the U.S. FPL to become the country's
leading producer of cellulose nanocrystals and TEMPO pretreated cellulose
nanofibrils.
This plant produces Cellulose Nanocrystals (CNCs) and TEMPO-based Cellulose
Nanofibrils (CNFs) for advanced process and product testing. Both materials
are currently being produced from bleached wood pulp in 400 liter glass
lined reactors selected to contain the concentrated acid and oxidation
conditions necessary for the production of CNCs and CNFs, respectively.
Typically, bleached wood pulp is the starting material for CNCs and
CNFs production. The resulting nanocrystals are approximately 5 nm in
diameter and 150 nm long, and the fibrils are about 20 nm in diameter
and up to 2 ? long. After extraction, both materials undergo extensive
purification in the membrane filtration system. CNCs will be available
for purchase in an aqueous suspension or freeze dried into a white powder.
CNFs can be cast into a clear film or freeze dried into an aerogel or
white powder. The substances' unique structural properties enable them
to strengthen a wide-range of materials such as films and fiber reinforced
composites.
Once CNCs and CNFs are firmly established products and their production
processes have been perfected, the pilot plant will be adapted to produce
material at a larger scale. The pilot plant was constructed with 4,000
liter reactors currently used as dilution and receiving vessels but
also available for a ten-fold scale up once continuous processing methods
are worked out for the initial purification. This additional scale-up
will begin to demonstrate the process methods suitable for pre-commercial
scale.
Over 1600 kilometers away at the University of Maine at Orono, the
Process Development Center (PDC) is currently expanding its pilot-scale
cellulose nanofibril (CNF) manufacturing plant. The University of Maine
PDC is the recipient of a $1.5 million grant from the U.S. Forest Service
to upgrade its nanocellulose pilot plant. The new pilot plant will be
capable of producing CNFs at a rate of one ton per day. This will be
the only facility capable of producing CNFs at this scale in the country.
Researchers and industrial companies interested in evaluating CNFs will
have a convenient source from which to purchase the material.
Cellulose nanofibrils are valued because of their strength - a strand
of it is stronger than steel. It takes on different structures depending
on how it is dried. When a sample of the CNF slurry is dried with heat,
the material becomes hard, dense and tough, and can be machined into
different shapes and sizes. When freeze-dried, the material is light-weight,
super-absorbent and demonstrates good insulating properties. The nanocellulose
fibrils are about 1,000 times smaller than paper fibers. The material
can be made from any lignocellulosic source, such as wood, grasses,
corn stalks or wheat straw.
UMaine already produces some cellulose nanofibrills via both mechanical
means and chemical means. Researchers and companies will be able to
order both CNF and CNC samples by fall of 2012. The PDC's work has already
garnered strong interest for the material. Visit http://umaine.edu/pdc/process-and-product-development/selected-projects/nanocellulose-facility/
to learn more, or request a sample of cellulose nanocrystals or nanofibrils.
In February 2012, Glenn Ostle of Paper360° magazine interviewed
John Moreau, President and CEO of CelluForce, the first semi-commercial
facility to produce nanocellulose. Moreau described the facility and
his company's plans (see the AOTC of Feb 1, 2012, "Making
nanotechnology pay"). Attendees at TAPPI's 6th International Conference
on Nanotechnology for Renewable Materials toured the facility in June
2012.
COLLABORATING FOR SUCCESS Countries in North America, Europe Asia and elsewhere are currently
placing great emphasis on the sustainable and safe use of materials.
CNCs are truly a wonderful material because of their inherent sustainability
and their low environmental, animal/human health and safety risks; all
this in addition to their abundance and promising physical, chemical,
and electrical properties.
Clayton Teague is currently a member of the TAPPI Board of Directors
(2012-2014 term). From 2003 until he retired in 2011, Dr. Teague was
Director, Federal National Nanotechnology Coordination Office. Prior
to this position, he was chief of the Manufacturing Metrology Division
in the Manufacturing Engineering Laboratory of the National Institute
of Standards and Technology, U.S. Department of Commerce. Colleen Walker,
Ph.D., is Project Manager and Technical Lead, TAPPI and can be contacted
at: cwalker@tappi.org.
Now that you
are Ahead of the Curve, stay there by joining TAPPI. |
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