Process-structure relationships in PCL foaming

The foaming behavior of poly(?-caprolactone) (PCL) with nitrogen as the foaming agent has been investigated. By using a uniquely designed and instrumented batch foaming apparatus it is possible to study the correlation between the foam structure (i.e., foam density and mean cell diameter) and the main processing variables (i.e., foaming temperature, foaming agent concentration, and pressure drop rate). A narrow experimental range has been used to describe the complex dependencies by a simple model. In particular, linear algebraic functions have been used to describe the effect of the processing variables on both the foam density and the mean cell diameter. With the aim to better depict these relationships, 3D graphs are also reported. This visualization/ parametrization allows the rapid selection of the proper process parameters to obtain PCL foams with the desired density and morphology. © SAGE Publications 2008.