Synthesis of continuous silicon carbide fibre

The structure of polycarbosilane is represented by three structural elements, but their quantification is difficult. Polycarbosilanes were synthesized by three methods and the respective molecular structures were examined by measurements of the molecular weight and the intrinsic viscosity, infrared, ultraviolet,¹H-,¹³C- and²⁹Si-NMR spectral measurements, and chemical analysis. The three structural elements (SiC₄, SiC₃H, SiC _x Si_4–x ) in the polycarbosilane molecule were determined quantitatively. By the comparison between¹H-NMR spectral data and calculation assuming a linear chain structure, the number of linkages in the unit consisting of ten silicon atoms was estimated to be 3 to 4. This result is in agreement with the result from the intrinsic viscosity; it was found that the shape of the polycarbosilane molecule is planar.