Core Properties

The core properties of CelluForce NCCTM allows its use in diverse applications leading to new or improved products and processes. The creativity and vision of CelluForce's dedicated technical staff and clients has led to innovations in various industrial sectors.

The core properties that can be used to improve products are as follows:

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Self-assembly

Self-assembles
The crystals that comprise CelluForce NCCTM interact with one another based on their size, charge and shape. Since nanoparticles are at a scale where they are in constant motion, the resulting energy allows the particles to self-organise.

Liquid crystals
Due to the CelluForce NCCTM crystals’ spindle shape, they can form liquid crystals: a state where there are domains of order within a fluid. As the fluid is concentrated, the spindles self-orient and form layers of crystals where each layer is oriented in the same direction. At a particular concentration, there is a phase separation into a phase where the domains exist and a phase where they do not. As the fluid is further concentrated, more of the fluid becomes organised until a film with only an ordered structure remains on a given surface.

Packing
This ordered structure creates a hard, smooth and tightly packed film. The packing is particularly tight for CelluForce NCCTM because the crystals contain a twist, allowing the spindles to interlock. Due to the chirality of CelluForce NCCTM, the twists in each crystal are in the same direction, resulting in even more effective packing.

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Strong

CelluForce NCCTM is an inherently strong material because of its high crystallinity. Each crystal has a stiffness that is of the order of 150 GPa and a tensile strength that is of the order of 10 GPa. These numbers are comparable to those of Kevlar™ as well as hard metals and their alloys. Many crystals are also inherently hard and incompressible and CNC is not an exception.

The crystals of CNC, however, are nanometric and are not strongly interconnected except in the structures laid down by nature from which they are isolated or when they are aggregated or incorporated into matrices and films.  

The challenge is to use CNC to impart greater stiffness, tensile strength, hardness and incompressibility to materials and therefore harness the power of what nature has provided. This challenge, which is now being met in various ways, is to ensure that the nanometric particles can be controlled in the way that they are distributed and that they are compatible with matrices to which they are part or to which they adhere.

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Thixotropic

Fluids containing CelluForce NCCTM are shear thinning, meaning they decrease in viscosity with the application of shear. This property provides the basis for several types of application. The degree of shear thinning is dependent on the rigidity, charge and shape of the crystal. These parameters amplify the effect of a small amount of CelluForce NCCTM by changing the effective particle diameter and can be affected and tuned by the interplay of other components of the system.

Methods of preparation that affect the rigidity, charge and shape of the crystal will also affect the rheology. For example, using methods that result in a carboxylated or uncharged crystal product will not yield the same properties as CelluForce NCCTM. The ongoing uniformity and purity of the product is also critical to obtaining consistent rheological properties. By the nature of the process used to make it, CelluForce NCCTM is both uniform and contaminant-free.

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Active

Hydroxyl Groups
Like all cellulose, CelluForce NCCTM is comprised of a linear, long-chain glucose polymer that is rich in oxygen, particularly hydroxyl groups. These hydroxyl groups develop the hydrogen bonds that give the CNC its inherent strength while providing a reactive surface of hydroxyl groups on two of the crystal’s facets. Though not all of the hydroxyl groups are equally reactive and accessible, they adequately allow a multitude of reactions. The hydroxyl groups are also the reason why CNC, unlike carbon nanotubes and other materials, is inherently hydrophilic.

Acidic Groups
CelluForce NCCTM surface is also comprised of acidic groups attached to its surface which allows for reaction with a variety of bases. Though many traditional products (such as cellulose acetate, carboxymethylcellulose and cellulose ethers) take advantage of the reactivity of cellulose, CelluForce NCCTM allows for the bonding of a variety of hydrophobic structures. This makes the material compatible with a wide range of solvents and polymer matrices.

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Photonic

Structural colour
CelluForce NCCTM forms solids with structural colour. As the ordered CelluForce NCCTM fluid becomes a solid, its colour is created by the interaction of light with the layered structures that are developed. Many animals and plants use structural colour rather than pigments or dyes to create vibrant, iridescent and durable displays.

Layers
As the layers develop, the charge that is on the crystal surfaces keeps the layers separated. The chiral twist in the crystals that make up a given layer results in a helical structure of layers wherein the orientation of the crystals in each layer is offset. This helix has periodic layers of crystals with the same orientation.

Periodicity
The periodicity of CelluForce NCCTM is of the order of the wavelength of light, which in turn is reflected and amplified through constructive interference. Because only one helical twist exists in the layers, the reflected light is polarised. The layer periodicity can be tuned by the addition of salts, by ultrasound and by the strength of the magnetic field. The observed colour is also affected by the viewing angle. Under polarised light, even the dynamic, layered structures within the fluids can be observed as birefringent patterns.

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High surface area

CelluForce NCCTM has an inherently high surface area. This is a result of the size of its separated particles, which is a function of the source of the cellulose and the process of extraction. Though CelluForce NCCTM is produced from wood pulp, crystals can also be derived from cellulosic materials produced from bacteria and certain invertebrate marine animals.

CelluForce NCCTM has a nominal average length of 150 nm and a nominal average diameter of 7.5 nm, giving a nominal aspect ratio of 20. This is shorter and often smaller than crystals from other vegetably derived cellulose materials, such as cotton, hemp and flax.

One gram of CNC nominally contains over 125 quadrillion (1016) particles, each with a nominal surface area of 4500 nm2, theoretically providing a surface area of about 550 m2/g of material. The surface area is affected by the quality of the particle dispersion in a media and whether the material has been dried or redispersed back into a medium.

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Electro-magnetic

CelluForce NCCTM is a charged material. The functional groups impart a negative charge to the surface of the crystal which, in turn, transmits electromagnetic properties to the crystal, to solid structures made with the crystal, and to fluids of which it is part. The electro-magnetic properties are different in each.

Fluids
The charge imparts electrical conductive properties to the fluid, which then becomes an electrolyte. However, this electrolyte differs from most in that the charge is on a suspended particle, imparting electrophoretic mobility and allowing the particle to migrate in an electric field. More uniquely, as the CNC particle is a nanoparticle with an aspect ratio, the particle orients itself in electro-magnetic fields even that of the Earth.

Solid structures made with the crystal
The charge imparts strong dielectric properties. Though there is no migration of charge when the material is placed in an electric field, there is a charge polarization where one surface of the structure becomes positively charged and the other becomes negatively charged. Solid structures also exhibit piezoelectric effects where the application of pressure can generate an electrical charge.