Chemiluminescence curves

In the published literature efforts exist to plot the so-called total chemiluminescence intensity (TLI) (surface below the chemiluminescence curve) vs. amount of oxygen absorbed [15]. In some cases a straight line may be obtained. A more detailed examination of the Equation (6) reveals that rate of oxygen uptake is in fact involved, so that we have... 

The case of reduction of chemiluminescence intensity for stabilized polymers of the chemiluminescence curves of the type (b) (Figure 5) has not yet been studied.)... 

The chemiluminescence curves of unstabi-and stabilized (B) polypropylene samples. 

Figure 5. The chemiluminescence curves of two acrylonitrile-butadiene-styrene copolymer samples A and B obtained at 150 and 190°C.

Figure 7. The chemiluminescence curves of annealed (a) and quenched (b) stabilized nylon.

Figure 8. The chemiluminescence curves of stabilized nylon sample aged in the air oven at 120 and 160°C for 16 hours and then exposed to ambient conditions for various time.

Generally, polyethylene exhibits a double sigmoidal shape on the isothermal chemiluminescence curve. Setnescu et al. interpreted the behavior as oxidation of very active sites (double bonds, branches, etc.) of PE and oxidative crystalline-phase conversion [34]. Zlatkevich suggested that overlaid sigmoids reflect two oxidation processes related to two kinds of peroxides with different stability assumed to exist in the oxidized polyolefins [35]. 

One of the chemiluminescence curves in ttie case when an oxygen-saturated solution of ethylbenzene was placed in the reaction vessel, is cited in Fig. 2. After introduction of the initiator, the chemiluminescence intensity rose rapidly, after which constant intensity of the luminescence was observed for a long time (curve 1). When the oxygen was almost entirely consumed, the concentration of radical RO began to decrease rapidly, which led to a decrease in the rate of recombination of these radicals and produced a decrease in the chemiluminescence intensity. At the lowest portion of curve 1, recombination of radicals R was observed, related to the smaller luminescence yield. 

Fig. 12 Chemiluminescence curves recorded for polypropylene modified with capsaicin, metallic selenium and capsaicin/metallic selenium couple. Additive concentration 0.25 % w/w testing temperature 190 °C ...

Fig. 49 The isothermal chemiluminescence curves recorded for various polymers containing benzene rings. The data were taken from [06J2]. (a) polystyrene at different temperatures (1) 230 C, (2) 220 °C, (3) 210 °C,...

The production of polymeric materials with high resistance against damaging runs by the addition of antioxidants and the crosslinking. LDPE subjected to photocrosslinking generates the chemiluminescence curves presented in Fig. 72 [93Z1]. 

Integration of the above system of differential equations using experimental and a parameters give an excellent fit with the chemiluminescence curve when dealing with single particles, but the quality of the fit deteriorated with groups of particles, as a result of multiple-spreading processes [26]. 

Diagram of the chemiluminescence curve for the oxidation of five isolated polypropylene particles (330 pm) compared to polypropylene particles in contact with each other [50]... 

The isolated polypropylene particles produce a chemiluminescence curve with five peaks that are assigned to individual particles. When the particles are in direct contact, the result is a curve with a single peak that, in its induction time, corresponds to the weakest previously found particle. 

Figure 10.52 shows chemiluminescence curves obtained from UV irradiated unstabilized polypropylene film. 

The early stage of the integrated chemiluminescence curve of polypropylene during photo-oxidation is shown in Figure 10.52. This figure shows rapid... 

Fig. 10.51, Chemiluminescence curves from polypropylene film (a) UV irradiated for 6 min and heated under nitrogen immediately (b) as for (a) but stored for 4 days in darkness before heating under nitrogen and (c) unirradiated film heated under nitrogen [723]. (Reproduced with permission from [723] published by Elsevier Science Publishers Ltd, 1991.)...

Figure 2.8 shows the chemiluminescence curves of PP, HDPE and their blend after the first extrusion step. The PP exhibits a sharp peak at the maximum on chemiluminescence intensity, whereas the HDPE curve shows a broad bimodal behaviour [36]. In the chemiluminescence curves of the blend, all these features were observed. This may be a strong indication of the existence of a two-phase system in the molten state, which was also pointed out by Braun and co-workers [37], although this was based on peroxide treatment of PP/PE blend melts. It appears that PP oxidises first and the oxidation sites created during this process accelerate, to some extent, the oxidation of PE phase. The overlap between the PP and PE traces in the blend can be interpreted as the interface of these two phases where the PE starts oxidising. In addition, the shape of the curves confirms that the oxidation mechanisms of these resins are different, and that this difference remains during the oxidation of the hlend in the molten state. 

Figure 2.8 Chemiluminescence curves of PP, PE and PP/PE blend after the second extrusion au = arbitrary units. Reproduced with permission from W. Camacho and S. Karlsson, Polymer Degradation and Stability, 2002, 78, 2, 385. 2002,...

Using the plot of / vs. [InH], one finds k-j at known v,- and The inhibitor is consumed during the experiment, and therefore, the chemiluminescence intensity increases. The kinetic curve of chemiluminescence is s-shaped. The maximum angular coefficient of the chemiluminescence curve is... 

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