Abstract: The pulse-modulated double irradiation ¹H NMR method is used to determine the content of hydroxyl, ethoxyl and vinyl gruops bonded to the silicon atoms in poly (dimethyl siloxanes). Only in a few minutes (150 times accumulation) the 0.064% vinyl content in the polymer is detected with this method.
In present paper, the determined results of eight samples are illustrated. The relative standard deviations are less than 5%.
As compared with usual method, the limit of instrument detecting active groups of the poly (dimethyl siloxanes) has been increased by about 1000 times and sampling time has also been decreased by several hundred times with this method. The disturbance of v₂ frequency is less than 0.5 ppm and the spectra resolutions have been proved.