PARTICLE ANALYSIS OF MICROCRYSTALLINE CELLULOSE - DIFFERENTIATION BETWEEN INDIVIDUAL PARTICLES AND THEIR AGGLOMERATES

The presence of two types of particles, the individual particles and their agglomerates, complicates the characterization of the particle size and the external surface area in the microcrystalline cellulose powders. During characterization, different degrees of de-agglomerations may be applied with varying size and surface areas as a result. The crystallinity of the cellulose particles were characterized by a crystallinity index, using the solid state NMR technique. Methods for the characterization of particle size, surface, shape of individual particles and their agglomerates were examined and recommendations of suitable methods are given. Individual particles were separated from agglomerates by ultrasonic treatment of a water suspension of agglomerates. Photoextinction measurements on sonicated water suspensions were used in the characterization of size and surface area of individual particles. The size of the agglomerates were estimated by dry sieving and the external surface area of the agglomerates with photoextinction measurements on cyclohexane suspensions not treated with ultrasonic energy.