Foaming of polysiloxane resins with ethanol: a new route to pyrolytic macrocellular SiOC foams

0447628 - ÚMCH 2016 RIV GB eng J - Journal Article
Strachota, Adam - Černý, Martin - Chlup, Zdeněk - Depa, Katarzyna - Šlouf, Miroslav - Sucharda, Zbyněk
Foaming of polysiloxane resins with ethanol: a new route to pyrolytic macrocellular SiOC foams.
Ceramics International. Roč. 41, č. 10 Part A (2015), s. 13561-13571. ISSN 0272-8842. E-ISSN 1873-3956
R&D Projects: GA ČR GAP107/12/2445
Institutional support: RVO:61389013 ; RVO:67985891 ; RVO:68081723
Keywords : silicon oxycarbide * siloxane * foams
Subject RIV: JI - Composite Materials; JH - Ceramics, Fire-Resistant Materials and Glass (USMH-B); JL - Materials Fatigue, Friction Mechanics (UFM-A)
Impact factor: 2.758, year: 2015

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.
Permanent Link: http://hdl.handle.net/11104/0251668