Foaming of polysiloxane resins with ethanol: A new route to pyrolytic macrocellular SiOC foams. Issue 10 (December 2015)

• Record Type: Journal Article
• Authors: Strachota, Adam; Černý, Martin; Chlup, Zdeněk; Depa, Katarzyna; Šlouf, Miroslav; Sucharda, Zbyněk
• Is Part Of: Ceramics international. Volume 41:Issue 10(2015)Part A
• Page Start: 13561
• Page End: 13571
• Publication Date: 2015-12
• Subjects: Silicon oxycarbide -- Siloxane -- Foams -- Sol–gel -- Pyrolysis; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2015.07.151
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Polysiloxane foams as precursors to silicon oxycarbide (SiOC) foams were prepared via simultaneous cure and foaming of liquid methylsiloxane resins, using the relatively environment-friendly ethanol as blowing additive of the boiling-solvent-type, and concentrated aqueous ammonia as catalyst. In order to achieve foam regularity, siloxane-based surfactants were added, and bubble nucleation by mechanical stirring was performed. The precursor foams were subsequently pyrolysed in nitrogen at 1000 °C, yielding SiOC foams as end products. The properties of the latter were fine-tuned during the foaming of the precursors, by the amount of added ethanol and by the time of mechanical stirring prior to foaming. The so-obtained SiOC foams displayed densities of 0.17–0.42 g/cm −3, corresponding to macro-porosities of 91–79%, compressive strength of 1–6 MPa, and elastic moduli of 0.2–1.6 GPa.