Pressurized fluid processing of polymers

A common way to process polymers is to heat them above their melting temperature. This is typically done in an extrusion process where polymer pellets are conveyed and heated by friction and heating elements. An important practical limitation of this method is due to the fact that polymers degrade at higher temperature. The so-called degradation temperature, Tdegrad, and its relative location versus the melting temperature, Tm, determine the processing window.

The processing window is practically important because it can be used to adjust the melt viscosity in

the process.

There is a range of polymers that could be processed if only the melting temperature could be reduced by few ten degrees.

Pressurized fluids, like CO2, are known to fluidize polymers at sufficient concentration. We want to use this effect to reduce the melting temperature of some new polymers and hence create a melt-processing window where there was none before. Important aspects of this work include the choice of the pressurized fluid and the polymer as well as the correct introduction of the pressurized fluid in the extrusion process. Last but not least it also includes the removal of the fluid when the melt is depressurized, because depressurization can lead to foaming at the extruder exit. We are working on this problem with the help of the first call SNF precoR funding scheme.

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