STABILIZATION AND MODIFICATION OF POLYCAPROAMIDE - Photochemical Reactions in Heterochain Polymers - page 35

In this connection, investigation of spectral - luminescent properties of PCA, containing
additives of bis-aroilenbenzimidazoles was carried out to evaluate the role of suppression
mechanism.
1.6.2. Spectral-Luminescent Properties of Stabilized PCA
According to the rule of ultra-violet absorbers selection the most effective stabilizers
must absorb not only in the field of absorption of polymer itself, but in the field of its
luminescence [24] that is the condition for realization of suppression mechanism of polymer
excited state.
Spectra of absorption and fluorescence of dyed compound XLY and initial PCA are
given in Figure 1.13. Characteristic peak of initial PCA fluorescence λ max em =425nm (curve I)
is absent in dyed polymer (curve 2). At the same time there appears new peak λ max em =530nm
corresponding to the emission spectrum of compound XLY (Figure 1.12.).
It should be noted that spectrum of dyed PCA excitation (Figure1.13., curve 3)
completely coincides with the spectrum of initial PCA fluorescence.
Figure 1.13. Spectra of absorption and luminescence of dyed and undyed PCA fibres: 1) luminescence
of initial PCA, 2) luminescence of PCA, dyed by XLY, 3) excitation of PCA, dyed by XLY, 4)
absorption of PCA, dyed by XLY, 5) absorption of initial PCA.