STABILIZATION AND MODIFICATION OF CELLULOSE DIACETATE - Photochemical Reactions in Heterochain Polymers - page 81

where τ 1 - time from the moment of application of load up to the break of a sample; τ[σ(t)] -
dependence of durability on stress and temperature.
This dependence may be presented in the form:

τ[σ(t)] = τ0·e [Uo-γ σ(t)]/RT (11)

where τ - time from the moment of application of load; U 0 - energy of activation of
structure elements change in the sample under stress; γ - structure-sensitive coefficient.
CA-film with the additives of BA and schiff's bases XXXIV, XXXV, XXXVI and
without additives was irradiated by mercury-quartz lamp at 50°C and irradiation intensity
equal to 4,40 J/cm 2 ·min during 10 hours.
Quantitative value of coefficient γ, being defined by the tangent of the slope of
dependence of durability logarithm 1gτ on the stress σ may be used as characteristic for
evaluation of light resistance.
Growth of γ for irradiated samples in comparison with non-irradiated ones characterizes
the degree of their light resistance decrease. Data on coefficient γ change in CA-films with
and without additives are given in Table 18.

Figure 2.25. Kinetic of optical density change in CDA-film containing azomethines at corresponding
Λmax: 1-330nm (BA), 2-272nm (XXXIV), 3-368nm (XXXV) in the process of irradiation by mercury-
quartz lamp.