FOAM INJECTION-MOLDING PROCESS DESIGNED TO PRODUCE SUB-MICRON CELLS

摘要

Significant progress has been made in recent years towards the production of low density foams with cell size around 100 nm. However, the process commonly used is batch foaming with high pressure CO2, which is not easily scalable and ill-suited for the production of larger specimen with controlled dimensions necessary for reliable property testing. A new approach to generate sub-microcellular foams with expansion ratio up to 4 by a modified injection- molding process is presented. Homogeneous polymer/CO2 mixtures produced by an extrusion foaming line are injected under controlled pressure into a variable thickness mold, which can then be opened at a controlled speed to adjust cell morphology. Foams with cell size below 500 nm were made by this process.