STABILIZATION AND MODIFICATION OF POLYCAPROAMIDE - Photochemical Reactions in Heterochain Polymers - page 27

Table 7. Data of X-ray diffraction analysis of dyed and undyed PCA-fibre

Structural characteristics PCA-fibre

dyed undyed

Intensity of diffraction maximum 1 m of relative unit 40 59

Angle of dispersion 2 0 10 0 30 10 0 40

150 130

Average angle of crystallites disorientation ∆ ϕ meas

61 85

Degree of crystallinity C K , %

Size of crystallites:
longitudinal, Aº
transversal, Aº

85 102

50 52

Sizes of both large and small SMV and their concentration have been defined in
connection with the fact that dependence of lg on φ 2 is not linear. Results of small-angle X-
rays measurements, which show that sizes of large SMV are 260-290 A and small- 60-80 A
with concentration of the order of 10 14 and 10 15 cm

−

, accordingly, are given in Table 8.
As it is seen from Table 8 the sizes of large SMV and, hence, their volume is decreasing
during fibres dyeing. It speaks about the fact that molecules of the dye enter into pores of
SMV. The dye enters into small SMV and besides the concentration of small SMV (N ∂ )

O

decreases by 20 times for factory fibres and 5 times - for laboratory one.

Table 8. Results of small-angle X-ray measurements of PCA fibres

Large SMV Small SMV

Sizes
of
voids,
A

Volume of
voids,
cm 3

Concentration
of voids,
cm 3

Sizes
of
voids,
A

Volume
of voids,
cm -
2 x10 19

Concentration
of voids,
cm -3 x10 15

PCA-fibre

17 14

1× 1×

Factory Initial 282 1,18 3,14 61 1,24 47,70

Dyed 264 0,96 3,5 69 1,73 2,23

Laboratory Initial 288 1,25 2,26 79 2,58 11,30

Dyed 260 0,93 3,38 69 1,73 2,23

Thus, the dye enters into small SMV filling in space of pores and, in addition, facilitates
fibre hardening, which, in its turn, influences photooxidative stability of PCA-fibres. These
data are proved by the results of physico-mechanical researches showing that dyed fibres
greatly exceed initial ones in photooxidative stability (Table 6).
Dye molecules, filling in SMV space, are connected with polymer molecules by forces of
physico-chemical interaction, at the expence of which load on cross-section of the fibre is
distributed more uniformly during the loading of dyed fibre and this leads to hardening of
fibres.
Thus, it is seen that thermostable dye XLY bis-(naphthoilenbenzimidazole) oxide
facilitates hardenening of PCA-fibres at ultra-violet irradiation when it is introduced into PCA
mass.