A study of the oxidation curing mechanism of polycarbosilane fibre by solid-state high-resolution nuclear magnetic resonance

The chemical structure of oxidation-cured polycarbosilane fibres has been studied by IR and chemical analysis, but its structure has not been identified in detail. In this work, the molecular structure was examined by chemical analysis, and solid state¹³C and²⁹Si nuclear magnetic resonance (NMR) spectroscopy. Si-O-Si, Si-O-C(I) and Si-O-C(II) bonds were formed by the oxidation curing process. The six chemical bonds (Si-C, Si-H, Si-Si, Si-O-Si, Si-O-C(I) and Si-O-C(II)) in oxidation-cured polycarbosilane were determined quantitatively, and the chemical structural model was shown. Solid state²⁹Si resolution NMR spectroscopy has proved to be a powerful tool for investigating the curing mechanism of oxidation-cured polycarbosilane fibres.