observed straight lines confirming first order reaction. The
slope of these lines gives us the reaction kinetics constant K.
Fig. 6 shows that with increasing peroxide level there is
a steady increase in rate constant K up to 180 C. At 190 C,
the values for 0.6 and 0.7 wt.% of peroxide are almost the
same and at 200 C there is even decrease in K value coming
from 0.6 to 0.7 wt.% of peroxide. The curve at 200 C
has a maximum at 0.6 wt.% of peroxide.
The full map of rate constant as a function of temperature
and peroxide content is shown by 3D plot in Fig. 7.
There is a strong exponential temperature dependence
while the effect of peroxide level on rate constant is much
smaller. The maximum value of rate constant for all temperatures
and peroxide levels was found to be at 0.6 wt.%
of peroxide and 200 C. Apparently, the higher loading of
peroxide (0.7 wt.%) does not speed up the cross-linking,
most likely the other reactions (like chain scission) make
the rate constant lower. The lowest rate constant value
was found for 0.2 wt.% of peroxide at 150 C, as summarized
in Table 1.
The inserted picture in Fig. 8 shows the plots according
to Arrhenius equation in logarithmic form (Eq. (6)) for
0.4 wt.% of peroxide. The linearity of these points was
rather good, measured by R values being 0.9966 for 0.4%
of peroxide. In this way all of the activation energies shown
in Fig. 8 were obtained. There is a steady increase in EA in
range 0.2–0.5 wt.% of peroxide with the maximum being at
around 0.52 wt.% and a decrease in range 0.55–0.7 wt.% of
peroxide. When the peroxide level is lower, mainly
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