Malvern Instruments' Sysmex analyser is set to change the way particles are characterised. The image analysis-based system fully automates the measurement not only of particle size but also particle shape. This represents a breakthrough for the many applications where shape, as well as size, affects the behaviour of particulate materials. Until now, the absence of a universal shape analysis technique has created difficulties in associating the function of particles with their shape characteristics, a problem that the new system is designed to solve.

Particle shape and size are important in ensuring consistent performance of a variety of materials. Examples include the manufacture of toners for printers and photocopiers, graphite and carbon for lithium batteries and a range of pharmaceutical applications.

The system uses patented technology which, as the result of experience in Japan, is already written into a number of toner manufacturers' patents as a reference measurement technique for quality control. The toner industry is highly competitive, with manufacturers seeking to develop performance advantages. Much has been achieved by controlling particle size and particle shape is the next parameter the industry would like to understand and control.

The size and shape of particles in a toner influence its image-forming ability, flow properties and charging capability. The toner's flow properties are affected by the circularity of particles, and it is this circularity that the Sysmex analyser measures. Circularity is a measure of the irregularity of the surface of a particle, with a value of 1.0 representing a perfect sphere. As the value decreases, the surface shape becomes more complex and the toner particle becomes coarser. The consequent reduction in flowability has an impact on image quality. Toners with low circularities also tend to be more abrasive, causing increased wear to the equipment.

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