Influence of temperature on the packing dynamics of polymer powders

Temperature influences drastically the physical properties of polymer powders. In the present study, the packing dynamics of polymer powders has been investigated with a modified version of GranuPack instrument, which is an improvement of the classical tapped density measurement.

Highlights

The tapped density measurement instrument GranuPack has been adapted to heat up the powder sample.

The packing dynamics of polymer powders is investigated at different temperatures.

The temperature corresponding to the onset of caking is measured.

A particular packing behaviour is evidenced for thermoplastic polyurethane (TPU).

The parameters extracted from packing curves are coherent with Differential Scanning Calorimetry (DSC) analysis.

After the filling procedure, the sample is heated and the evolution of the density is measured after each tap. For a selection of four polymers (polyamide 12, Polystyrene, Polyvinyl chloride and a thermoplastic polyurethane), the influence of temperature on the Hausner ratio and on the packing dynamics are analysed. We show that the packing dynamics is drastically influenced by temperature even far below the melting temperature $T_{m}$ for semi-crystalline polymers and far below the glass-transition temperatures $T_{g}$ for amorphous polymers. In addition, we show that the analysis of the packing dynamics at different temperatures allows to determine a characteristic temperature corresponding to the onset of caking. Finally, we show that this temperature is coherent with Differential Scanning Calorimetry (DSC) analysis. Continue on Influence of temperature on the packing dynamics of polymer powders