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Licensed Unlicensed Requires Authentication Published by De Gruyter June 22, 2020

Microcellular Thermosetting Polyurethane Foams

C. Brondi , M. R. Di Caprio , E. Di Maio , T. Mosciatti , S. Cavalca , V. Parenti and S. Iannace


Thermosetting polyurethane foams are nowadays produced with typical bubble size, d > 150 μm, with plenty of room for improvement towards the cellular structure refinement, to gain, among others, in the thermal insulation performances. We herein report a first example of a microcellular thermosetting polyurethane foam, i. e. with bubble size below 5 μm, produced via the gas foaming technology. In particular, high-pressure CO2, N2 and their mixtures were utilized as blowing agents: solubilized separately into the polymer precursors, they were brought into a supersaturated state by a pressure reduction to induce the bubble nucleation and growth. To achieve microcellular foams, we made use of a novel two-stage pressure reduction program, concurrent to the polymer curing. The first stage is a pressure quench O (10–2 s) from the saturation pressure to an intermediate pressure to induce the nucleation of a large amount of dense bubbles. The second stage is a slow O (102 s) further pressure decrease to ambient pressure, allowing for a slow bubble growth, designed to reach ambient pressure exactly when the curing reached completion.

*Correspondence address, Mail address: Ernesto Di Maio, Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, University of Naples Federico II, P.le Tecchio 80, 80125 Naples, Italy, E-mail:


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Received: 2020-01-21
Accepted: 2020-02-12
Published Online: 2020-06-22
Published in Print: 2020-07-03

© 2020, Carl Hanser Verlag, Munich

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