FT-IR Spectrometric Determination of Styrene Monomer in Copolymer of Styrene and Methylmethacrylate

Sample film of thickness of 0.05 mm was made with 0.013 g of the sample by the film-forming press under a working pressure of 30 MPa at (150±10) ℃.In the IR-spectrometric determination of styrene monomer in the copolymer of styrene (SR) and methyl methacrylate (MMA),based on the IR-spectroscopic property of the copolymer,wavenumbers of 700 cm-1 and 1 730 cm-1 were selected as the peak positions for analysis.Copolymer samples with known contents of styrene monomer was used for preparation of standard curve,taking the contents (in %) of styrene monomer as the ordinate and values of ratio of characteristic peak area,A700/A1 730,as the abscissa.Content of styrene monomer in unknown sample was found from the standard curve with the value of the ratio A700/A1 730 measured.Range of determination of this method was found over the range 40%-85% of styrene monomer.Values of RSD′s (n=6) found by this method were in the range of 0.9%-1.9%.Relative deviation within 2% were obtained between results of the present method and the 13C NMR method.