473667 The Use of the Viscoelasticity in Polymer Foaming to Obtain a Fully Opened Cell Structure

Monday, November 14, 2016: 10:06 AM
Yosemite C (Hilton San Francisco Union Square)
Daniele Tammaro1, Rossana Pasquino2, Massimiliano M. Villone2, Gaetano D’Avino2, Ernesto Di Maio2, Nino Grizzuti2 and Pier Luca Maffettone2, (1)Department of Chemical, Materials and Production Engineering, Faculty of Engineering, University of Naples Federico II, Naples, Italy, (2)Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, University of Naples Federico II, Napoli, Italy

In this work a design tool to control cell-opening in gas foaming of thermoplastic semicrystalline polymers is developed. The sequence of events following bubble nucleation, namely, bubble growth and impingement, are modeled to gain a comprehensive, perspective view on the mechanisms of bubble wall rupture and on the conditions for achieving a fully opened cell morphology by flow induced crystallization. In particular, unlike the previously published literature, the polymer elastic recovery is recognized as an important factor for wall retraction, often dominant with respect to surface tension, which is typically considered as the only driving force determining the retraction of ruptured bubble walls. The new approach is experimentally validated on poly(e-caprolactone) (PCL), foamed with CO2, as a model polymer/gas system.

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