STABILIZATION AND MODIFICATION OF CELLULOSE DIACETATE - Photochemical Reactions in Heterochain Polymers - page 93

Substitution of hydrogen for alkyl residue in heteroatom of carbazole cycle causes high
level photoprotective effect even at 0,5% stabilizer cocentration in polymer, the more so, this
effect doesn't change considerably with futher increasing of concentration (Table 20 XXVI
and XXIII compounds).
Inhibiting influence undergoes notable change depending on substituent in both carbazole
cycle, and in amine component. Thus, carbazole sulphuryl amides derived from aliphatic
amines (XXVIII, XXIII, XXII) show lower activity, than those of acrylamin derivatives
(XXVIII, XXVII). Substituent intrusion into phenylen rings results in sharp increase of light
stabilizing activity in carbazole derivatives, as well as in those of indan (XXVI and XXX
compounds or XVI and XVIII compounds). Thus, intruding electron accepting substituents (-
NO 2 ) couses greater stabilization of CDA, than penetration of electron donation particles (-
СН 3 , -ОН, -NН 2 ). Possibly, it is connected with ability of electron accepting particles to draw
forward electronic density of benzene ring, as a result, carbon atoms get positive charge and
hydrogen connected with them becomes mobile.
Comparing of stabilizing activity among electron donation substituents allows us to
notice, that the stronger electron donating properties are exposed, the greater is light
stabilizing effect (compound XX - substituent -NН 2 (62,2%); compound XVIII - substituent
-ОН (37,9%), compound ХVII- substituent -СН 3 (33,3%).
It is important to notice, that sulphuryl amides derivatives of both indan and carbazole
have a number of valuable properties of practical application: they are resistant to thermical
shock (Т decomp =120-300 0 С); non-toxic (LD 50 =1000 mg/kg); well consistent with CDA in
common solvents; acquire small volatility.
Screening of formerly unknown sulphur containing compounds on the basis of benzo/B/-
thiophene for their light stabilizing activity was carried out with the purpose of stabilizers
assortment expansion. Corresponding data of specific viscosity conservation of 0,5% acetone
solutions of CDA with different content of benzo/B/-thiophene are given in Table 23.
Table 23. Ultra-violet irradiation effect on the conservation of specific viscosity of
0,5 CDA solutions

Stabilizer Stabilizer concentration, % of polymer mass

1 2 3 5 10

I - 37,1 - - -

II - 63,3 - 64,0 61,1

III 44,0 55,6 86,2 - -

IV 39,2 - 66,9 - -

IV 36,1 - 58,6 - -

V,VI 38,0 42,1 - 84,2 -

VII - 56,8 - - 77,8

VIII 24,3 47,5 76,7 82,4 -

IX 82,7 87,9 - 72,8 -

Tinuvine-II - 34,4 - - -

Screening showed that derivatives of benzo/ B /-thiophene effectively prevent
photooxidative destruction of polymer, exceeding well-known industrial stabilizer. It has been
found that increase of CC concentration does not cause considerable rise of light stabilizing