Coupling extrusion and supercritical CO2: a newprocess for a homogeneous inclusion of fragilemolecules in polymer matrix

摘要

Extrusion is a process widely used industrially for the formulation of finely divided solidsinto polymeric matrices. But, il implies high temperatures and mechanical constraints, pr*hihiting the use of fragile molecules, as found in pharmaceuticals. In this work, we havedeveloped a supercritical carbon dioxide (SC CO2)-assisted extrusion process, which leadsto the manufacturing of nano-structured polymeric foams. SC-C02 modifies the rheologicalproperties of the material in the barrel of the extruder and acts as a blowing agent dur-ing the relaxation at the passage through the die. For experiments, a single-screw extruder(SCAMEX, France) was modified to be able to inject SC Co2 within the extruded material.Experiments were carried out using polystyrene (PS) and the effect of operating temperatureon material porosity was studied. Polystyrene with an expansion rate about 15 to 25% wasmanufactured and moreover, controlling the temperature allowed to control the porosity.