The market for cellulose nanocrystals. Renewable bio-based polymers and composites derived from natural resources are of great commercial interest due to the depletion of fossil fuel resources and the environmental impact of fossil fuel-based plastic products.
Many bio-based polymers have been developed, but they have shortcomings that render them unsuitable for many applications. The use of cellulose based nanomaterials is therefore viewed as a means to improve the performance of bio-based polymers in market such as packaging and automotive, without compromising their properties and sustainability. Their development, especially in the automotive industry in Japan, is growing fast.
Nanocellulose can be obtained by disintegration of plant cellulose pulp or by the action of specific types of bacteria. Nanocelluloses can be derived from plants (e.g., wood, wheat straw, potato pulp) or via bacterial processes.
Nanocellulose exists in a number of forms including:
- Homogenized cellulose pulps: microfibrillated cellulose (MFC) or nanofibrillated cellulose (NFC). MFC is both a distinct product and also categorized along with NFC by a number of companies. NFC is by far the most widely produced nanocellulose material.
- Acid hydrolyzed cellulose whiskers: nanocrystalline cellulose (NCC) or cellulose nanocrystal (CNC).
- Bacterially produced cellulose: bacterial cellulose (BC). Also referred to as bacterial nanocellulose (BNC) or microbial cellulose.
Table 1: Types of nanocellulose.
| Nanocellulose type | Diameter | Length | Crystallinity |
| NanoFibrillar Cellulose (NFC) | 20 – 300 nm | > 2,000 nm | < 70% |
| NanoCrystalline Cellulose (NCC) | 3 -5 nm | 50 – 500 nm | up to > 90% |
| Bacterial cellulose (BC) | 10 – 100 nm | 100 to >1000 nm | ~70% |
Source: Future Markets.
What is nanocrystalline cellulose (NCC) or cellulose nanocrystals (CNC)?
By treating cellulose materials such as plants, tunicates and agriculture biomass with concentrated acids (acid hydrolysis), the amorphous regions can be broken up, thereby producing nano-sized cellulose-based crystals called nanocrystalline cellulose (NCC) or cellulose nanocrystals (CNC).
Figure 1: NCC suspension TEM.
Image credit: Cellulose Lab.
CNC are elongated, rigid and rod-like or whisker-shaped particles with a rectangular cross-section. These materials can be prepared from any cellulose source materials including wood pulp, recycled paper and paperboard, cotton fibres, hemp, flax, bamboo, sugarcane bagasse and other agro-biomass.
CNC that are derived from wood pulp have dimensions of approximately 5 nanometers (nm) in diameter and 150-200 nanometers in length. Larger crystals can be produced using cotton (10 nm by 500 nm) or algae (20 nm by 1000nm).
CNC possesses many desirable properties such as high surface area, hydroxyl groups for functionalization, colloidal stability, low toxicity, chirality and mechanical strength. It is
- Lighter than aluminum
- Stiffer than Kevlar
- Higher strength than steel
Image credit: Celluforce.
Properties
CNCs possess a range of enhanced mechanical, thermal, and optical properties, including:
High aspect ratio
CNC has a high aspect ratio (length to width ratio) with typical lateral dimensions of 100-200 nanometers (nm) and longitudinal dimension of 5-20 nm. Their dimensions vary depending on the native cellulose source, extraction methods and recovery processes such as hydrolysis time and temperature.
High strength
CNC has high tensile strength and can be compared to Kevlar fibre in stiffness, making it an excellent material for reinforcement of natural or synthetic matrix polymers. CNC has been used as the filler phase in bio-based polymer matrices to produce bio-based nanocomposite with superior thermal and mechanical properties. They are also attractive due to their sustainability and biodegradability and exceptional optical and surface properties.
Rheological properties
CNC has unique rheological properties. Dispersions of CNC at low concentrations provide high viscosity that is used in non-caloric stabilizers for food industry. In addition, CNC are highly shear thinning – a property which is particularly important in different coating applications as well as an ideal value-added bio-material with potential for utilization in stimulation, fracturing and completion fluids.
Optical properties
CNC has low density and exhibits other benefits such as optical properties that can be altered or controlled. CNCs possess unique optical and electromagnetic properties originating from their ability to form chiral nematic organisation under the influence of the Earth’s magnet.
Barrier
CNC in composite films is considered to be gas impermeable and has been suggested to act as a barrier material for perishable foods and materials which are sensitive to air and oxidation. CNC also possesses the ability to form self-standing films.
Applications
Main application markets for CNC are packaging, aerospace composites, automotive composites, and consumer goods such as electronics and appliances. CNC is very hydrophilic and it is difficult to disperse this material in the more hydrophobic precursors of thermosets and thermoplastics in order to produce biocomposites. To enhance the chemical compatibility between CNCs and a matrix, the CNCs are usually hydrophobized. This can be done either by the adsorption of a hydrophobic cation by the sulfate groups, or by chemical modification of the CNC surfaces
Other sectors where applications are being explored include oil and gas, food, hygiene, absorbent products, medical, cosmetic and pharmaceutical industries.
University of Alberta researchers have developed a hydrogel formulation by using a nanocrystalline cellulose (NCC) polymer that has potential to prevent biofilm formation via physical resistance mechanism. Given that 80% of microbial infections in the body are caused by biofilms, preventing biofilm-formation via medical devices provides an effective strategy for prevention of bacterial infection.
The formulation has been validated by coating urinary catheters. Data has shown that the formulation is 99% effective at reducing initial bacterial adhesion (by depletion of colonization-induced bacterial flocculation) and subsequent biofilm formation on various surfaces. Urinary catheters are placed on 15-25% of hospitalized patients and result in more than 560,000 catheter-associated urinary tract infections (CAUTI) in the US. Annual estimated CAUTI costs are as high as $1.8 billion.
Figure 2: CNC slurry.
Image credit: Cellulose lab.
Composites
Applications include:
- Biodegradable and renewable nanocomposites.
- Packaging.
- Flexible packaging composites.
Coatings/fllms
- Coatings for flexible packaging.1
- Iridescent films in textile and security industries.
- Nanocomposite films with good transparency and thermal stability.2
- Biobased and biodegradable barrier coating on food packaging.
Figure 3: An iridescent biomimetic cellulose multilayer film remains after water that contains cellulose nanocrystals evaporates. Credit: Silvia Vignolini.
Electronics
- Biodegradable Flexible electronics-fully recyclable flexible paper electronic devices.3
- Conductive inks.
Sensors
- Piezoelectric sensors.4
- Flexible sensors.
Filtration
- Mesoporous films and membranes.
- Water filters.
Medical
- Biocomposites for bone replacement and tooth repair.
- Drug delivery.5
- Protein immobilisation.
- Wound dressings.
Energy
- Flexible batteries.
Oil and gas
- Nanofluid in enhanced oil recovery.6
- Drilling fluids.
Other applications of cellulose nanocrystals include:
- Food additives.
- Adhesives.
- Catalysts.
- Cosmetics.
- Hydrogels.
- Viscosity modifiers and flow aids.
Companies
Commercial CNC is available from a small number of producers. Challenges that have been identified in the production process that hinder mass production include:
- process consumes huge amounts of water
- recycling the strong acid catalyst is difficult
- purification steps are cumbersome, particularly with lengthy dialysis.
American Process, Inc.
USA
http://www.americanprocess.com/
American Process Inc.’s patented AVAP® technology offers commercial-scale production of nanocellulose with flexibility in final product morphology and surface properties (hydrophilic or hydrophobic). BioPlus™ Nanocellulose Fibrils and Crystals. BioPlus-L Crystals, lignin coated hydrophobic cellulose nanocrystals, are available in gel form and in the form of a redispersible spray dried powder. The company offer both the hydrophilic versions of CNF and CNC as well as proprietary lignin coated hydrophobic varieties which overcomes the well-known grand challenge of compatibility with hydrophobic polymers.
The company has a Pre-commercial demonstration plant for NCC and NFC and has further plans for a commercial scale plant for 2019.
Figure 4: Blue Goose Biorefineries CNC production process.
Blue Goose Biorefineries, Inc.
Canada
https://bluegoosebiorefineries.com/
Blue Goose Biorefineries uses a unique, environmentally benign and patent pending nano-technology procedure for producing high value bioproducts from residual agricultural and forestry biomass resources. The technology is very diverse as it is suitable for a wide range of biomass sources from agriculture and forestry and generates many end products including high value cellulose, lignin and hemicellulose and their degradation products in the form of platform chemicals.
The company produces BGB Ultra™ CNC and BGB Natural CNC for technical evaluation. Advantages of the product include:
- Diverse biomass source capabilities
- Economical at low production volumes
- Upper production limits theoretically in the same scale as current pulp mills
- Reaction temperatures below 90o C
- Reactions at regular atmospheric pressure
- No toxic or corrosive chemical environments exist in the process
- Easily transitions into existing equipment (pulp mills, food processors, biorefineries)
- Effluent is nontoxic and treatable with conventional processes.
Samples are available online. Production capacity is 35 kg/week of CNC. The production process, R3TM process technology uses an oxidative, nano-catalytic process to fractionate biomass.
Celluforce, Inc.
Canada
http://www.celluforce.com/
In January 2012, Celluforce officially inaugurated the world’s first NanoCrystalline Cellulose (NCC) demonstration plant at the Domtar pulp and paper mill site in Windsor, Quebec. The production target is one ton per day. Trials integrating NCC into the manufacturing process of different products are currently taking place through technical collaboration agreements between CelluForce and 15 companies based in Canada, the United States, Europe and Asia in four main industrial sectors: paints and coatings, films and barriers, textiles, and composites. The company is a joint venture of Domtar Corporation and FPInnovations.
Figure 5: NCCTM Process.
The company is the largest integrated manufacturer and marketer of uncoated freesheet paper in North America and the second largest in the world based on production capacity. Target price for their materials is approx.
Celluforce Inc. has the only demonstration-scale NCC pilot plant currently operating in Canada. This facility was built as a joint venture between FPInnovations and Domtar. The company’s product is branded CelluForce NCC.
Figure 6: CNC produced at Tech Futures’ pilot plant; cloudy suspension (1 wt.%), gel-like (10 wt.%), flake-like crystals, and very fine powder.
Product advantages include:
- Abundant, renewable, recyclable.
- Non-toxic.7
- Commercially orientated product development.
Production capacity is approximately 1 ton per day.
The pulp undergoes a reaction process that removes the amorphous components, leaving high purity cellulose crystals intact. These crystals are then separated, cleaned and dried to form a powder material for shipment. CelluForce recycles the chemicals used in the production process, and converts sugars into energy, for reuse in the system.
InnoTech Alberta
Canada
https://innotechalberta.ca/
InnoTech Alberta operates a CNC pilot plant, producing kilogram/day quantities. The company is a subsidiary of Alberta Innovates (http://bio.albertainnovates.ca). The 100 kg/week CNC Pilot Plant located in Edmonton was commissioned in 2013.The company has a collaboration with Hokuetsu Kishu Paper Inc. to develop CNC.
Figure 7: Cellulose Nanocrystals (CNC) pilot plant, Edmonton (Image credit: InnoTech Alberta).
Melodea/Holmen
Israel
http://www.melodea.eu/
The company is a spin-off from HUJI and the European FP7 programme “Woody Project”. The company has an investment agreement with HOLMEN AB, Sweden. They produce NCC from pulp and paper waste that is developed as nanostructured foams for sandwich composites applications. End user markets targeted are wind energy, transportation and building and construction Production capacity is 0.1 ton per day pilot plant producing CNC from paper mill sludge.
University of Maine
USA
http://umaine.edu/pdc/process-and-product-development/selected-projects/nanocellulose-facility/
The UMaine Process Development Center produces CNC and cellulose nanofibrils (CNF). The CNC is manufactured at the US Forest Service’s Cellulose Nanomaterials Pilot Plant at the Forest Products Laboratory (FPL), located in Madison, Wisconsin. CNCs is produced via chemical process and spray dried for shipping. CNC slurry is also available.
Valentis Nanotech
Israel
http://valentis-nano.com/
The company combines nanoparticles with cellulose nanocrystals (CNC) to produce polymer films. Used as a coating for increased strength or as a barrier against UV rays, oxygen and moisture, these films can be used in a diverse range of applications.
REFERENCES
1. http://www.tappi.org/content/events/10nano/papers/7.1.pdf
2. Multi-functional coating of cellulose nanocrystals for flexible packaging applications, http://link.springer.com/article/10.1007%2Fs10570-013-0015-3
3. Let It Shine: A Transparent and Photoluminescent Foldable Nanocellulose/Quantum Dot Paper, http://pubs.acs.org/doi/abs/10.1021/acsami.5b02011
4. http://butler.cc.tut.fi/~trantala/opetus/files/FS-1550.Fysiikan.seminaari/Fileita/SampoTuukkanen-10Sep15.pdf
5. Cellulose Nanocrystal Microcapsules as Tunable Cages for Nano- and Microparticles, http://pubs.acs.org/doi/abs/10.1021/acsnano.5b03905
6. The Potential of a Novel Nanofluid in Enhancing Oil Recovery, http://pubs.acs.org/doi/abs/10.1021/acs.energyfuels.6b00244
7. https://www.pwc.com/ca/en/forest-paper-packaging/publications/20150506_celluforce_goguen.pdf
