Chemiluminescence and charge-recombination luminescence

10 mol dm s may be studied, which correspond to free-radical concentrations of lO radicals dm , which in an analytical volume of 1 ml gives a sensitivity - 1000 times that of ESR (Section 3.3.2). 

In principle, the CL from polyolefins could be used as a monitor of the extent of oxidation during reactive extrusion in the presence of peroxides to decrease the molar mass (Brown, 1992), but this has not been reported. Attention has been paid to the effect that change in viscosity of a polymerizing network has on the CL profile, as described in the following section. 

the fluorescence intensity and lifetime increased with viscosity (Equation (3.30)) since it has a structure too similar to that of the molecular rotors (Levy, 1984). Thus, on combining the two relations, it would be expected that 

However, it was also shown that the CL-time profile was sensitive to the purity of the resin and the amine, DDS, which was found to contain a quenching agent, so the quantum yield of emission was reduced in the fluid state (Equation (3.28)). It is therefore concluded that simple CL experiments are not genemlly applicable as a method for monitoring the cure of epoxy resins. In addition to the self-probe fluorescence of TGDDM, the CL measurements rely on absolute emission intensities, which, in the absence of an internal standard for calibration, is unreliable. 

It was noted above that measurements of the lifetime of emission provide an alternative way of accessing the photophysical parameters of a polymer. The analogous approach in CL is to subject the oxidizing polymer to an external perturbation and then observe the change in CL as the system returns to the steady state (George, 1981). This will genemlly take the form of a short period of UV irradiation after which there is a burst of CL followed by decay, which may be analysed according to an assumed kinetic model, such as second-order 

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