Chemistry Reference
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Table 26. Amount of water in % from the mass of the sample, released during warming
up dyed PVA in vacuum during an hour
Temperature, °C
Undyed PVA
PVA, dyed by colours
LIX
LX
LXI
LXII
LXIII
LXIV
175
0,3
0
0,4
0
0
0
0
200
2,4
2,3
2,4
1,9
2,1
0
0,8
225
5,8
7,2
6,5
8,5
9,1
1,9
2,9
250
12,7
7,6
12,3
9,7
11,5
4,1
5,1
300
12,2
-
-
-
-
8,2
-
From the data of Table 26 it is seen that H
2
O quantitatively being released at thermal
decomposition of initial PVA and PVA dyed by inactive forms LIX and LXI, in being
investigated temperature range, is characterized by close coefficients, what was to be
expected, because oxichlortriazine dyes are not able to react with OH - PVA groups. Quantity
of released water in PVA samples, covalently linked with dyes LIX, LXI, LXIII, at 250°C is
much smaller than in initial PVA, moreover the least water is released from a sample dyed by
phthalocyanine dyes of LXIII type. Substantive phthalocyanine dye LX behave somewhat
differently than inactive forms of dyes LIX and LXI which is probably connected with the
possibility of partial blocking by it OH-groups of PVA by means of complex-formation
shown in works [73,79] for the series of direct dyes.
Results of EPR and viscosimetric investigations of dyed and undyed PVA-films are
worth of attention.
So, before irradiation the dye LIX did not have paramagnetic properties. EPR signal in
the form of singlet appears only after 4 hours of irradiation (Figure 2.39). This signal is
stable, its intensity changes a little and in an hour after stopping irradiation. The signal
disappears when irradiated dye is being dissolved in water.
Unlike LIX the dye LXIII displays paramagnetic properties and before irradiation. EPR -
spectrum, shown in Figure 2.39, is a singlet.
Figure 2.39. EPR - spectra of dyes LIX (a) and LXIII (b) after 4 hours ultra-violet irradiation.
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