CONTINUOUS EXTRUSION OF NANOCELLULAR FOAM

摘要

Nanocellular foams are typically produced with supercritical CO2 by a solid state batch foaming process. Low temperatures allow for the stabilization of a high number of nuclei that can be generated by controlling the pressure and pressure drop rate. Yet such a process is not easily applicable to future commercial production due to long saturation times and finite autoclave volume. This limitation can be removed by adapting the nanofoaming process to continuous production. Modifications to a simplified foam extrusion system made it possible to produce sub-microcellular acrylic foams with bimodal and monomodal cell distributions. Optimization of extrusion conditions led to homogeneous foams with four-fold expansion and cell nucleation densities over 10~(14)/cm~3.