Study on the Curing Methods of Thermosetting Polysilazanes

ABSTRACT Thermosetting PSZ‐ICMA (polysilazane functionalized by 2‐isocyanatoethyl methacrylate) was investigated regarding to the different curing methods, that is, hydrogen‐transfer addition of HDI (hexamethylene diisocyanate), radical polymerization by TBPB ( tert‐ butyl peroxybenzoate); photopolymerization by ethyl(2,4,6‐trimethylbenzoyl)phenylphosphinate; and catalytical polymerization by NiNA (nickel naphthenate). When PSZs are cured by HDI, with the increase of HDI content, the gelation time gradually decreases; the exothermic peaks of DSC (differential scanning calorimetry) exit at 104°C and 192°C; and the weight loss during curing decreases to 27.3%. When PSZ‐ICMAs are cured by TBPB, with the increase of ICMA content, the gelation time gradually shortens; the exothermic peak shifts slightly higher; and the weight loss during curing decreases. When PSZ‐ICMAs are cured by photopolymerization, with the increase of ICMA content, the exothermic peaks of subsequent thermal cure maintain steadily. When PSZ‐ICMAs are cured by NiNA, with the increase of ICMA content, the gelation time shortens remarkably; the exothermic peaks shift to lower positions, whereas the weight loss during curing decreases; with the increase of NiNA content, the gelation time shortens quickly; the exothermic peaks shift to lower temperatures, and the weight loss during curing decreases to 19.9%. All cured polysilazanes are verified to have high ceramic conversion yield.