Determination of Amorphous Content of Spray Dried Lactose by Solution

In the injection moulding process the manufactured plastic components may carry asignificant amount of charge which has undesirable consequences in some applications e.g.in dry powder inhalers (DPI's). In high resistivity polymers, the charge may lie in the bulk ofthe material which prevents typical neutralizing procedures such as use of ionizers. Insteadof neutralizing the injection moulded components, the process parameters were adjusted tominimize the charge of the melt. Electrostatic charges on manufactured polypropylene testrods were measured using a Faraday cup. By adjusting several process parameters such asfeeding cylinder and mould temperatures, cooling time, injection speed and holding pressurethe generated charge on the polypropylene test rod could be reduced ten times compared tothe charge values obtained with the initial process parameters. Taguchi matrix was used inassessing the effect of separate process parameters on the generated charge. Electric fieldmeasurements showed that the samples were not polarized and that the charge was uniformlydistributed. Charge decay measurements showed that after storage some samples with highinitial charges still carried higher charges than did initially samples which were producedwith optimized parameters. Together with electrostatic measurements, physical dimensionsof the samples were also monitored to ensure the usability of the products. Also, sampleswere characterized by differential scanning calorimetry. Results prove that a significantreduction in the static charge was achieved by optimizing the process parameters using theTaguchi matrix.