Chemistry Reference
In-Depth Information
For intensification of PCS lightstabilizing action there were obtained PCS with end amine
groups, inhibiting by which, as it is supposed, proceeds according to the following scheme:
R*+R
1
N
2
Æ
RH+R
1
N*H;
where R - polymer radical.
Shielding action of azomethines is explained by the fact that they, owing to conjugation,
turn luminous energy into heat energy or some other energy, which does not influence the
process of polymer photochemical transformation. That is why, the longer is the conjugation
chain the stronger is shielding ability of PCS.
Oligomer products of diamine condensation with carbonyl compounds, using excess of
one of bifunctional compounds have been used lately. These products are used as stabilizers
of thermooxidative destruction for different polymers, moreover oligomer stabilizers are more
interesting because they are washed out from the polymer at photofading and sweated out,
while in use least of all [294].
In the work [177] compounds on the basis of isomeric dianhydrides 4,4' bis - tetraphenyl
(4,5 dicarboxynaph - 1-yl) phenyl benzophenone, and in the work [295] - sulfonamides were
used as additives of polyfunctional action.
From the ecological and economic points of view it is necessary to search for such
compounds which would combine dyeing, stabilizing, plasticizing and other properties, that
is, it is necessary to search for additives of polyfunctional action.
Thus, information on modifying additives of polyfunctional action being used at present
is represented mainly by patent works. Inorganic and organic compounds such as black, ultra-
violet absorbers on the basis of benzophenone derivatives, inhibitors of radical processes-
piperidines and stable nitroxyl radicals and so on - mainly colourless compounds, are
recommended as modifying additives. However, problems of the effect of modifiers on
photo- and thermal destruction of PETP are not completely interpreted in literature. Besides,
different researchers come to different conclusions.
In some works direction of using different dyeing additives, including organic dyes, as
PETP modifiers is being developed. Optical bleaches, disperse dyes, dyes of anthraquinone
series, azo and phthalocyan dyes have found their application for this purpose.
At the same time stabilizing activity of dyes depends to a great extent on the method of
their introduction into PETP composition.
Since the products from polyesters are obtained from the melt then suitable assortment of
such dyes is highly limited and this defines the search of new compounds possessing high
thermal stability and resistance to agressive reducing medium of PETP melt. Economic
advantages of additives introduced into polymer mass compared with other dyeing methods
should be also noted here.
PCS are the most interesting from the series of potential highmolecular modifiers.
However, problems of such modifiers effect on polymer properties are not fully studied in
literature.
From the economic and ecological points of view it is more reasonable to search for
compounds with polyfunctional properties: thermal stabilizer, light stabilizer, antioxidant,
plasticizer, dye and so on.
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