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Shape Memory Polymer Foam with Programmable Apertures

: Walter, Mario; Friess, Fabian; Krus, Martin; Hassan Zolanvari, Seyed Mohammad; Grün, Gunnar; Kröber, Hartmut; Pretsch, Thorsten

Volltext urn:nbn:de:0011-n-5997074 (7.4 MByte PDF)
MD5 Fingerprint: abb468dced46453ac282cb28c4c75c7c
Erstellt am: 18.9.2020

Polymers. Online resource 12 (2020), Nr.9, Art. 1914, 23 S.
ISSN: 2073-4360
Fraunhofer-Gesellschaft FhG
Schaumstoffe aus Formgedächtnispolymer
Zeitschriftenaufsatz, Elektronische Publikation
Fraunhofer IAP ()
foam; programmable material; polyester urethane urea; actuation; construction; air slot

In this work, a novel type of polyester urethane urea (PEUU) foam is introduced. The foam was produced by reactive foaming using a mixture of poly(1,10decamethylene adipate) diol and poly(1,4butylene adipate) diol, 4,4?-diphenylmethane diisocyanate, 1,4butanediol, diethanolamine and water as blowing agent. As determined by differential scanning calorimetry, the melting of the ester-based phases occurred at temperatures in between 25 °C and 61 °C, while the crystallization transition spread from 48 °C to 20 °C. The mechanical properties of the foam were simulated with the hyperplastic models Neo-Hookean and Ogden, whereby the latter showed a better agreement with the experimental data as evidenced by a Pearson correlation coefficient R² above 0.99. Once thermomechanically treated, the foam exhibited a maximum actuation of 13.7% inheating-cooling cycles under a constant external load. In turn, thermal cycling under load-free conditions resulted in an actuation of more than 10%. Good thermal insulation properties were demonstrated by thermal conductivities of 0.039 W·(m·K)-1 in the pristine state and 0.052 W·(m·K)-1in a state after compression by 50%, respectively. Finally, three demonstrators were developed, which closed an aperture or opened it again simply by changing the temperature. The self-sufficient material behavior is particularly promising in the construction industry, where programmable air slots offer the prospect of a dynamic insulation system for an adaptive building envelope.