This document discusses nanocellulose, which refers to nano-structured cellulose that can be produced from wood pulp and other cellulose sources. Nanocellulose includes cellulose nanofibers (CNF), microfibrillated cellulose (MFC), and nanocrystalline cellulose (NCC). Nanocellulose is pseudo-plastic and exhibits thixotropy, becoming less viscous when shaken. It has a wide range of applications including in paper, composites, food products, medical products, and as a reinforcement material.

1. PAVIN PRAIZE SUNNY
2017-27-001
Ph.D. Forestry (Wood Science)

4. Nanocellulose is a term referring to nano-structured cellulose. This may be either
cellulose nanofibers (CNF) also called microfibrillated cellulose (MFC),
nanocrystalline cellulose (NCC or CNC), or bacterial nanocellulose, which refers
to nano-structured cellulose produced by bacteria.
CNF is a material composed of nanosized cellulose fibrils with a high aspect ratio
(length to width ratio).
It is pseudo-plastic and exhibits thixotropy, the property of certain gels or fluids
that are thick (viscous) under normal conditions, but become less viscous when
shaken or agitated.

5. Nanocellulose also called as microfibrillated cellulose (MFC), is a material,
which is composed of nanosized cellulose fibrils that have got high aspect ratio
(length to width ratio).
Most typical dimensions ranges from 5–20 nanometers width and length can
range up to 2000 nanometers.
It is pseudo-plastic and poses the property of certain gels that are viscous under
normal conditions. Its flow becomes thin, less viscous over the time when it is
shaken, agitated, or pressurized.

6. This kind of property of nanocellulose is called as thixotropy. When the shearing
forces are removed the gel regains much of its original state. The fibrils are isolated
from any cellulose.
The most common source of nanocellulose includes wood-based fibers (through
high-pressure, high temperature and high velocity impact homogenization).
Nanocellulose can also be obtained from native fibers by an acid hydrolysis,
giving rise to highly crystalline and rigid nanoparticles (often referred to as CNC or
nanowhiskers) which are shorter (100s to 1000 nanometers) than the nanofibrils
obtained through homogenization, microfluiodization or grinding routes.

7. The terminology microfibrillated/nanocellulose or (MFC) was first used by
Turbak, Snyder and Sandberg in the late 1970s at the ITT (International
Telephone and Telegraph Corporation) Rayonier labs in Whippany, New Jersey,
USA.
To describe a product prepared as a gel type material by passing wood pulp
through a Gaulin type milk homogenizer at high temperatures and high pressures
followed by ejection impact against a hard surface.

9. Manufacture:
Nanocellulose, which is also called cellulose nanofibers (CNF), microfibrillated
cellulose (MFC) or nanocrystallinecellulose (NCC), can be prepared from any
cellulose source material, but woodpulp is normally used.
The nanocellulose fibrils may be isolated from the wood-based fibers using
mechanical methods which expose the pulp to high shear forces, ripping the larger
wood-fibres apart into nanofibers.
Cellulose nanowhiskers are rodlike highly crystalline particles (relative
crystallinity index above 75%) with a rectangular cross section. They are formed by
the acid hydrolysis of native cellulose fibers commonly using sulfuric or
hydrochloric acid.

10. Amorphous sections of native cellulose are hydrolysed and after careful timing,
crystalline sections can be retrieved from the acid solution by centrifugation and
washing.
Their dimensions depend on the native cellulose source material, and hydrolysis
time and temperature.

11. Nanocellulose recycling chart

12. Structure and properties:
The ultrastructure of nanocellulose derived from various sources has been
extensively studied. Techniques such as transmission electron microscopy
(TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM),
wide angle X-ray scattering (WAXS), small incidence angle X-ray diffraction and
solid state 13C cross-polarization magic angle spinning (CP/MAS), nuclear
magnetic resonance (NMR) and spectroscopy have been used to
characterizetypically dried nanocellulose morphology.
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13. AFM (Atomic Force Microscopy) height image of carboxymethylated
nanocellulose adsorbed on a silica surface. The scanned surface area is 1 µm2

14. A combination of microscopic techniques with image analysis can provide
information on fibril widths, it is more difficult to determine fibril lengths,because
of entanglements and difficulties in identifying both ends of individual nanofibrils.
Also, nanocellulose suspensions may not be homogeneous and can consist of
various structural components, including cellulose nanofibrils and nanofibril
bundles.
Pulp chemistry has a significant influence on nanocellulose microstructure.
Carboxymethylation increases the numbers of charged groups on the fibril
surfaces, making the fibrils easier to liberate and results in smaller and more
uniform fibril widths (5–15 nm) compared to enzymatically pre-treated
nanocellulose, where the fibril widths were 10–30 nm.

15. Viscosity:
The high viscosity at lownanocellulose concentrations makes nanocellulose
very interesting as a non-caloric stabilizer and gellant in food applications, the
major field explored by the early investigators.
The dynamic rheological properties were investigated in great detail and
revealed that the storage and loss modulus were independent of the angular
frequency at all nanocellulose concentrations between 0.125% to 5.9%.
The storage modulus values are particularly high (104 Pa at 3% concentration)
compared to results for cellulose nanowhiskers (102 Pa at 3% concentration).

16. There is also a particular strong concentration dependence as the storage modulus
increases orders of magnitude if the concentration is increased from 0.125% to
5.9%.
Nanocellulose gels are also highly shear thinning (the viscosity is lost upon
introduction of the shear forces).
The shear-thinning behaviour is particularly useful in a range of different coating
applications.

17. Mechanical properties:
 Crystalline cellulose has interesting mechanical properties for use in material
applications. Its tensile strength is about 500MPa, similar to that of aluminium.
Its stiffness is about 140–220 GPa, comparable with that of Kevlar and better
than that of glass fiber, both of which are used commercially to reinforce plastics.
Films made from nanocellulose have high strength (over 200 MPa), high
stiffness (around 20 GPa) and high strain (12%). Its strength/weight ratio is 8
times that of stainless steel.
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18. Foams:
oNanocellulose-based foams are being studied for packaging applications in order to
replace polystyrene-based foams.
oNanocellulose can also be used to make aerogels/foams, either homogeneously or
in composite formulations.

19. Surface modification:
• The surface modification of nanocellulose is currently receiving a large amount of
attention.
• Nanocellulose displays a high concentration of hydroxyl groups at the surface
which can be reacted. However, hydrogen bonding strongly affects the reactivity of
the surface hydroxyl groups.
• In addition, impurities at the surface of nanocellulose such as glucosidic and lignin
fragments need to be removed before surface modification to obtain acceptable
reproducibility between different batches.

20. Applications:
Paper and paperboard
Composite
Food
Hygiene and absorbent products
Emulsion and dispersion
Oil recovery
Medical, cosmetic and pharmaceutical
GaAs (Gallium Arsenide) electronics on
nanocellulose substrate

22. Other applications
• Activate the dissolution of cellulose in different
solvents.
• Regenerated cellulose products, such as fibers
films, cellulose derivatives
• Reinforcement of conductive materials
• Loud-speaker membranes
• Computer components
• High-flux membranes
• Corrosion inhibitors
• Organometallic modified nanocellulose in
battery separators
• Tobacco filter additive
• Lightweight body armour and ballistic glass
• Capacitors
Bendable solar cell on
nanocellulose substrate