Nano Materials and Agglomeration
Most nanomaterials of commercial interest are produced as powders. Being “nano”, the powder particles will normally measure less than 100nm in at least one dimension. Unfortunately, as with powders at larger scales, the particles will generally have a preference to stick together due to minute electrostatic forces between them. These so-called Van der Waals forces increase relatively dramatically as the particle sizes reduce, making the job of separating the particles much harder for nano materials than for larger particles. However, unless the particles are separated to expose their enormous surface area, they remain as clumps or agglomerates and behave chemically and physically much like equivalent-sized macro particles. The problem is especially difficult when nano powders are added to fluids to create useful products, e.g. coatings, plastics, composite resins and inks. This is because the particles are much harder to separate and keep separated in a fluid matrix. Most methods of separation, or “dispersion”, involve high intensity mixing, but much of the mixing energy applied to the fluid is wasted as the forces are dissipated by the fluid matrix surrounding the agglomerates. This usually makes the process ineffective and inefficient, especially with larger production volumes.
These dispersion problems often mean that the remarkable properties of nano materials are not realised in real-world applications. In fact, the difficulty of dispersing nano materials in fluids has been termed the “single biggest factor in slow adoption of nano technology in products”. Whilst laboratory methods have been developed at small scales, very little has been available at medium and large scale to serve the needs of major product companies. Poor efficiencies have also meant that costs have been high, limiting the possibilities for mass-market adoption.
Industrial Nano Dispersion
As a toll processor, Industrial Nano is able to select the best available equipment for dispersion and has invested significantly in process development. The core dispersion tools have been developed specifically for Industrial Nano by Maelstrom Advanced Process Technologies Ltd., a UK company specialising in high energy mixing. Using Maelstrom’s range of patented ultra-high speed FDM and FDM2 machines, Industrial Nano is able to deliver leading edge dispersion and de-agglomeration performance at scales up to 1 tonne per hour across a wide range of viscosities. Shear rates of 107 s-1 are typical for most mixtures. Ultrasonic mixers can also be used on certain customer materials to good effect. Industrial Nano’s use of extrusion technology combined with special blending mixers also means that nano powders can be incorporated into plastics for use in sheeting and moulding applications. With its multi-step process, Industrial Nano brings together nano powders, bulk fluids (from liquid solvents to plastic pellets) and other recipe ingredients to form masterbatches or final mixtures. Plastic mixtures can also be pelletised for customers’ ease of use.