Peroxy group, analysis

Quantitative analysis of the peroxy group of macroinitiators is performed by iodometry [38] and that of the azo group is done by ultraviolet (UV) spectrometry. Recently, type II MAI composed of PU was determined of its azo concentration by UV [20]. When the UV absorption spectral peak of the azo group overlaps other peaks, DSC is available by determining the azo group from the exothermal peak area [1IJ. 

The mobility of one nitro group of TNM suggested originally that one nitro group possesses a different structure from the others, for example, the nitrite or peroxy structure. This proved to be wrong and it has now been firmly established by X-ray analysis that TNM possesses a perfectly symmetrical structure [161] - Fig. 34. This was substantiated by dipole moment measurement which has been found to be equal to 0 within the experimental error. Electron diffraction also confirmed the symmetrical structure of TNM [162]. 

Pathway (b) proceeds via hydrogen atom abstraction by OH radicals, from the CH2 group adjacent to the amine group of NMP. This leads to the formation of an alkyl radical which reacts with dissolved O2 to form another peroxy radical. This peroxy radical can also sclf-rcact to form a tetroxide, which rapidly decomposes into NMS and 5-HNMP. From the HPLC analysis a value of 55 1 % can be put on the importance of this pathway. 

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