Publication Details (including relevant citation information):
Blakey, I.; George, G. A.; Billingham, N. C., Macromolecules 2001, 34 (26), 9130-9138.
The mechanism of chemiluminescence (CL) during thermal oxidn. of polypropylene (PP) was probed by doping PP with an energy acceptor (9,10-dibromoanthracene [DBA]) and a chemiluminescence (CL) activator (9,10-diphenylanthracene [DPA]). Doping PP with DBA had little effect on the shape of the CL intensity (ICL)-time profile. This suggests that energy transfer from triplet states is probably not significant in the scheme of PP CL. However, the CL activator (DPA) had a significant effect on the shape and intensity of the ICL-time profile. In the absence of DPA, the ICL-time profile matches the profile for the formation of carbonyl-contg. oxidn. products from FTIR-emission spectra. In contrast, in the presence of DPA, it was the integrated DPA ICL-time profile which matched the oxidn. product profile, indicating that now ICL was proportional to the hydroperoxide concn. It is suggested that peroxides formed during PP oxidn. are capable of reacting with DPA to produce chem. induced electron exchange luminescence (CIEEL). It is also suggested that CL from undoped PP, i.e., direct CL, may also occur by a CIEEL mechanism. This mechanism is believed to involve the reaction of PP peroxides with an easily oxidizable luminescent oxidn. product. For the detector system used in this study the majority of light emitted is consistent with reactions between acyl peroxides and a,b-unsatd. carbonyls. The consequences of this mechanism are that the ICL-time curve measured during the oxidn. of PP may reflect either the hydroperoxide profile or the oxidn. product profile depending on the spectral wavelength analyzed or the state of purity of the polymer.
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