Structure optimization of polycaprolactone foams by using mixtures of CO₂ and N₂ as blowing agents

Abstract

Abstract The foaming process of poly(ϵ‐caprolactone) (PCL) with carbon dioxide and nitrogen has been investigated in this work from a theoretical and experimental point of view. CO 2 and N 2 showed very different behavior, as foaming agents for PCL. This was due to the different transport, chemical, and physical properties of the polymer/gas mixture that led to different foam morphology in terms of density, cell number density, and cell size. The lowest density (0.03 g/cm 3 ) was obtained with CO 2 , but the highest number of cells with N 2 (although with a higher density, (0.2 g/cm 3 ). Foam with a low‐density microcellular structure, was obtained when a mixture of the two gases was employed. POLYM. ENG. SCI., 45:432–441, 2005. © 2005 Society of Plastics Engineers