STABILIZATION AND MODIFICATION OF POLYCAPROAMIDE - Photochemical Reactions in Heterochain Polymers - page 25

practical importance; change of these indexes at fibres irradiation may characterize
photooxidative stability of the polymer.
Fibres, containing derivatives of bis-aroilenbenzimidazole, were subjected to ultra-violet
light action of the lamp PRK-2. Mechanical properties of the fibres were determined
depending on cross section area. Value of rupture stress (σ) is the mean value of true rupture
stress obtained from indexes of tearing machine.
Stabilized fibres, containing 0,6 mass % of the XLY compound, were obtained by
introducing additive at the stage of producing polymeric concentrate of the dye and the others
- by usual method of polymer crumb powdering before polymer melting and fibre forming.
Data on physico - mechanical indexes of PCA fibres stabilized by XLY compounds are given
in Table 6. From these data it follows that stabilized fibres greatly exceed unstabilized ones
according to photooxidative stability.
Table 6. Physico-mechanical indexes of stabilized polycaproamide fibre before and after
24-hours irradiation by mercury-quartz lamp

Polymer
sample

Concentr
ation of
additive,
%

Rupture stress σ, Mpa Rupture extension, ε, % Conservation, %

before
irradiation

after
irradiation

before
irradiation

after
irradiation

before
irradiation

after
irradiation

PCA
initial

- 325,68 154,99 122 86 47,6 70,5

PCA +
XLY
additive

0,25 333,48 264,01 128 90 79,2 70,3

-//- 0,50 340,76 285,69 130 98 83,8 75,4

-//- 0,60* 339,35 284,51 124 97 83,9 78,2

-//- 1,00 341,73 317,12 116 106 92,8 91,4

-//- 2,00 335,30 277,62 118 91 82,8 77,1

*was obtained through the stage of polymeric concentrate of the dye.

The reason of increased photooxidative stability is not only stabilizing activity of bis-
aroilenbenzimidazoles derivatives but also the effect of these compounds on supermolecular
structure of polymer matrix. As it is seen from the Table 6 physico - mechanical indexes of
polymer do not practically depend on the method of additives introduction. Data of Table 6.
agree with data of Table 5. In all cases the greatest degree of conservation of polymer initial
properties is registered at the concentration of XLY compound - 1 mass %.

1.4. E FFECT OF D ERIVATIVES OF B IS -A ROILENBENZIMIDAZOLE ON
S UPERMOLECULAR S TRUCTURE OF PCA - F IBRES

Electron - microscopic photographs of dyed and undyed PCA fibres before and after
ultra-violet irradiation were obtained to clarify possible effect of bis-aroilenbenzimidazole
derivatives on supermolecular structure of PCA fibres by the method of raster electronic
microscopy (REM) with increase of 12000 times. Any specific details of the structure were
not observed in the initial sample. After irradiation the initial sample undergoes great