Viscosity studies of poly(DL -lactic acid) in supercritical CO 2

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  • University of Nottingham


The effect of supercritical CO 2 on the viscosity and activation energy to viscous flow of P DLLA is investigated, using a high pressure parallel plate rheometer, over a range of temperatures (50-140 °C) and pressures (5-12 MPa). The Cross model is fitted to the data to enable calculation of the zero shear viscosity and critical shear rate. A significant decrease in the viscosity is observed on increasing both variables; however, at high temperatures, the pressure effect becomes negligible. An increase in the critical shear rate is also observed on raising the pressure, indicative of a reduction in the relaxation time of the polymer. Manipulation of the Arrhenius equation shows a reduction in the activation energy to viscous flow as the pressure is increased. Together, these results show that the melt processing temperature of P DLLA can be reduced in the presence of supercritical and high pressure CO 2.


Original languageEnglish
Pages (from-to)1383-1393
Number of pages11
JournalJournal of Polymer Science, Part B: Polymer Physics
Issue number19
Publication statusPublished - 1 Oct 2012


  • activation energy, polylactide, processing, supercritical CO, viscosity