SiOC ceramic foams derived from polymethylphenylsiloxane precursor with starch as foaming agent

SiOC (“black glass”) ceramic foam was prepared by the foaming of a preceramic polymer, polymethylphenylsiloxane resin, and by its subsequent pyrolysis conducted up to 1000 °C. Prior to foaming, corn starch was blended with the diluted resin, in order to achieve uniform and small-sized pores. The foaming of the polymer blend was carried out simultaneously with its crosslinking: escaping water vapour (forming from starch) served as the blowing agent. The apparent foam density can be controlled by adjusting the foaming temperature or by varying the amount of added starch. Both ways were used to prepare foam samples with porosity in the range of 70–90%. The porosity-dependent compressive strength of these foams was found to be in the range of 1–16 MPa.