Nitroxide decay kinetics photoinitiation

The direct correlation observed in this study between gloss loss rates and photoinitiation rates suggests that the nitroxide doping technique could provide a rapid test for the evaluation of coating durability. Measurements of nitroxide decay kinetics to determine coating photoinitiation rates can be made at near ambient exposure conditions in a few days (compared to years for... 

As discussed above, it is necessary to extrapolate the nitroxide loss kinetics to zero nitroxide concentration in order to determine the photoinitiation rate of the coating. Shown in Figure 9 is a plot of initial nitroxide decay rate versus initial nitroxide concentration for the six coatings studied. Over the nitroxide concentration range studied, the decay rate was found to be linear in nitroxide concentration The slopes and intercepts are given coatings. The slope is a measure of abstraction by excited nitroxide in intercept is the rate of formation of... 

Both the nitroxide decay measuranents of free-radical photoinitiation rates and nitroxide kinetics during HALS stabilization depend on accurate, quantitative measurements of nitroxide concentrations in cross-linked polymers. Quantification of radical concentrations by ESR requires a suitable primary standard, careful sample preparation, a reference standard with which to monitor spectrometer performance, and most important, reproducible positioning of the samples in the resonance cavity of the spectrometer. Most of the experiments described here were carried out with a Bruker-IBM ER 200 D spectrometer equipped with an Aspect 2000 Data System. Because these coatings are cured at temperatures as high as 130°C, the primary nitroxide standard, which was introduced into the coating prior to cure, had to be... 

Derivation of Nitroxide Radical Decay Kinetics and Free-Radical Photoinitiation Rates... 

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