Differentiation of hydroperoxide groups by reaction with sulphur dioxide

3 Differentiation of hydroperoxide groups by reaction with sulphur dioxide 

In order to differentiate hydroperoxide (OOH) groups from hydroxyl groups (OH), oxidized polymer samples can be exposed to sulphur dioxide (SOj), which reacts only with OOH groups, and new absorption bands at 1196, 1040 and 900 cm are formed, attributed to the formation of C—O—O—C linkages [642, 740, 741, 927, 1494, 1844, 1846, 2081]  

After SO2 treatment, bands at 3550 cm (isolated OOH), 3440 cm (hydro-gen-bonded OOH) and 870 cm (stretching O—OH) partially or completely disappear (Fig. 10.67). The SO2 treatment should be as short as possible (1-4 h) in order to avoid side reactions. After SO2 treatment the new band at 1332 cm Ms formed, which belongs to the SO2 which diffuses into the sample. 

Exposure of the S02-treated polyolefin films to gaseous NH3 for a few hours leads to a change in the IR spectra. The new band positions and relative intensities at 1420 cm and 620 cm and the intense absorption at 1105 cm can be attributed to the formation of ammonium sulphate (NH4)2S04 in the polymer matrix [362]. 

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