Ann Newman - "Relationship of Triboelectric Charging and Dielectric Properties of Pharmaceutically-Relevant Mixtures" D.A.Engers, M.N.Fricke, A.W.Newman,K.R.Morris

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      Publication Details (including relevant citation   information):

      J. Electrostat., 2007, 65,   571-581.


      Binary mixtures of pharmaceutically relevant powders were   investigated using dielectric spectroscopy over a frequency range   of 10−3 to 300 kHz. Two different binary mixtures were   studied as a function of concentration; pseudoephedrine   hydrochloride in dicalcium phosphate dihydrate and acetaminophen   in microcrystalline cellulose, respectively. Dielectric   properties obtained from measurements of these systems are   reported and found to follow a trend similar to the observed   triboelectric behavior after low-shear tumble blending. Powder   samples for charge measurement were mixed using a stainless steel   blender and dispensed directly into a Faraday pail. For the two   binary mixtures studied, low-frequency conductivity calculated   from the imaginary part of the complex permittivity (or loss   factor) was observed to be sensitive to water content.   Furthermore, the unanticipated trends previously reported in the   measured specific charge after blending were observed to   correspond with the surface charge density calculated from the   capacitance of the composite material. The implications of   moisture and the physical and chemical properties of these   dielectric mixtures are also discussed with supporting results.

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