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Photodestruction of PETP was studied under the action of ultra-violet light with different
wave length 254 and 313nm. Intensity of incident light was 28 J/m 2 c. Samples were prepared
from initial and modified by HC-1 and HC-2 (1% of mass) PETP - fibres.
Under service conditions polymer materials are often subjected to simultaneous action of
irradiation and other external factors in stressed state. Study of these complicated cases of
destruction, when mechanically loaded polymer material is additionally subjected to the
action for such external factor as ultra-violet irradiation, is considered to be important -
scientific and practical - problem in physics and chemistry of polymers [304].
Figure 3.19. Kinetic curves of PETP - fibres decay in the air: 1 - unmodified; 2 - modified by HC-1; 3
- modified by HC-2; 4 - modified by HC-3; 5 - modified by HC-4; 6 - modified by HC-5; 7 -
modified by HC-6; 8 - modified by HC-7.
In the work [305] it is shown that the load limits possible set of means of polymer
stabilization and a number of light stabilizers, used for stabilization of non-loaded polymer
samples, appeared to be low-effective for light stabilization of stressed samples. In connection
with this light stabilizing effect of hexaazocyclanes has been studied not only under
conditions of photoageing, but also of photomechanical destruction of PETP.
Results of the effect of preliminary ultra-violet irradiation by the light with different
wave length on strength characteristics of initial and modified samples are given in Figure
3.20. From the figure it is seen that breaking strength of initial and ,modified samples without
irradiation is different, however, comparison of results is not clear enough. For more evidence
dependence of P on irradiation time for initial and stabilized samples, given in Figure 3.21,
has been constructed according to these data, using formula:
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