Particle Characterisation

Particles are described by a large number of attributes, most of which exhibit wide fluctuations within a sample. In order to have a good understanding of their behaviour it is important to analyse their characteristics, such as size and shape distributions, mechanical properties, adhesive properties etc. Particle size is a simple concept that is complicated by the particle shape. So both size and shape can rarely be described adequately by a single measure, hence a great number of descriptors exist for their characterisation. We have a wide range of facilities for this purpose form state of the art X-ray micro-tomography, Scanning Electron Microscopy, Malvern Pananalytical Mastersizer 3000, Morphologi G3 and Spraytec instruments to sieving.

The response of a particle to compression and breakage is governed by mechanical properties, such as Young’s modulus, hardness and fracture toughness. We have specially-developed instruments for their measurements, e.g. nano-indentation, nano-crushing, impact testing, Particle Shear and Impact tester.

A degree of adhesion is usually present between particles and any surfaces they contact. The magnitude of this adhesive force is dependent on the surface chemistry and the size of the particles. Our research group has developed a quick and simple test device for estimating the characteristic adhesive force for a bulk sample. This approach, known as the drop test method, applies a rapid deceleration force to particles adhered to a substrate. Contacting particles must also overcome friction in order to slide past one another. The frictional force between particles can be assessed using a pin-on-disk device known as the Micromaterials NanoCrush.

• Measurement of Adhesion Force Between Particles by the Drop Test Method

• Molecular and Structural Design of Nano-Assemblies for Controlled Release: Part A – Production and Characterisation of Nano-assemblies
• The Effect of Processing Methods on the Mechanical Properties of Powders
• Breakage of Catalyst Carrier Particles
• Characterisation of Mechanical Properties of Pharmaceutical Crystals by Nanoindentation: Hardness, Young’s Modulus and Fracture Toughness
• Formation, Processing and Characterisation of Pharmaceutical Powders

1. Zafar, U., Hare, C., Hassanpour, A., and Ghadiri, M.,"Drop Test: A New Method to Measure the Particle Adhesion Force ", Powder Technology, Submitted
2. Liu, Y., Calvert, G., Hare, C., Ghadiri, M., Matsusaka, S., 2012, " Size measurement of dry ice particles produced from liquid carbon dioxide ", Journal of Aerosol Science, 48, 1-9.
3. Olusanmi, D., Roberts, K., Ghadiri, M., Ding, Y. 2011. "The breakage of Aspirin under quasi-static indentation and single particle loading: Effect of crystallographic anisotropy", International Journal of Pharmaceutics, 411(1-2), 49-63.
4. Supuk, E., Seiler, C., and Ghadiri, M., 2009, "Analysis of a Simple Test Device for Tribo-Charging of Bulk Powders", Particle and Particle Systems Characterization, 26, 7-16.
5. Watanabe, H., Ghadiri, M., Matsuyama, T., Ding, Y., Pitt, K.G. , 2007, "New instrument for tribocharge measurement due to single particle impacts", Review of Scientific Instruments, 78(2), 024706/1-024706/5.
6. Hassanpour, A. and Ghadiri, M., 2007, "Characterisation of flowability of loosely compacted cohesive powders by indentation", Particle and Particle Systems Characterisation, 24 (2), 117-123.
7. Hassanpour, A., Ghadiri, M. , 2004, "Distinct element analysis and experimental evaluation of the Heckel analysis of bulk powder compression", Powder Technology, 141, 251-261.