Analysis Of Polydimethylsilane By Pyrolysis-Gas Chromatography-Mass Spectrometry

Polycarbosilane(PCS) is used as the precursor for the preparation of high-performance silicon carbide fibers.It is synthesized from polydimethylsilane (PDMS) through Kumada rearrangements.Therefore,the quality of PCS is strongly dependent upon that of PDMS.PDMS is infusible and insoluble in normal solvents,making the analysis of its chemical structure very difficult.In order to establish the quality control standard of PDMS,the basic information about the molecule structure of the pyrolytic product of PDMS was investigated with on-line pyrolysis-gas chromatography-mass spectrometry(Py-GC-MS).A new method has been put forth to calculate the abundance of C,Si,and C isotopes in organosilicon compounds.Fragment Finder V3.0r has been successfully used for the analysis of Py-GC-MS(Pyrolysis-Gas Chromatography Mass Spectrometry) spectra.By using this new method,the chemical structure of the species evolved from PDMS during pyrolysis can be readily resolved.The calculated values have been compared with the experimental results to illustrate the application of this method on the determination of PDMS chemical structures.