STABILIZATION AND MODIFICATION OF CELLULOSE DIACETATE - Photochemical Reactions in Heterochain Polymers - page 71

same effect is achieved at relatively small concentration. Since for XXXV- W o /W st ·i φ >1, then,
in the given case, there is additional mechanism of protection, excepting shielding;
specifically XXXV may play the role of antioxidant, inhibitor of radical processes or
suppressor of excited states.

Table 16. Effect of additives of ultraviolet absorbers on the rate of acetic acid
accumulation at irradiation of CDA in the air by the light (253,7 nm)

Additive % of CA mass i φ W 0 /W st 0 /W st · i φ

Tinuvine II 2,0 1,66 2,10 1,30

Tinuvine II 3,8 1,71 3,50 2,00

2-oxy-4-methoxybenzophenone 2,0 1,50 1,40 0,90

2-oxy-4-methoxybenzophenone 3,8 1,61 2,10 1,30

XXXV 0,5 1,22 2,00 1,64

XXXV 2,0 2,55 4,38 1,72

XXXV 3,0 5,20 7,78 1,50

XXXV 3,8 3,77 4,05 1,07

CA irradiation of stabilized XXXV in the air and in vacuum under the same conditions
was carried out to prove antioxygenic activity of PAC, taking the rate of acetic acid
accumulation for characteristic of phototransformation with regard to correction for shielding.
Data of the experiment are given in Figure 2.15 (curves 2 and 3).

Figure 2.15. Content of free CH3COOH in the process of irradiation be the lamp PRK - 2. 1 - CDA -
film without additive; 2 - CDA - film, containing BA; 3 - CDA - film, containing XXXIV; 4 - CDA -
film, containing XXXV.