STABILIZATION AND MODIFICATION OF POLYCAPROAMIDE - Photochemical Reactions in Heterochain Polymers - page 10

Interest in N, N 1 - diaryloxamides [67], as the class of non-toxic ultra-violet absorbers
possessing light efficiency has raised lately:
These compounds are similar to such industrial stabilizers as Sanduvor V.5.4 - 2 - ethyl
- 2 - ethoxydiphenyloxamide and Sanduvor V.5.4 - 5 - tretbutyl - 2 - etoxy -
ethyldiphenyloxamide [68]. Stabilizing effect of such compounds is realized mainly
according to physical mechanism of stabilization; reactions of radical inhibition are
improbable [69].
Great attention in literature is paid to stabilizers - spatially difficult amines and their
derivatives [10, 70] -, which act as inhibitors of radical processes of polymer destruction.
Difficult piperidines and their nitroxyl radicals are among them:
However, they are ineffective in the presence of peroxides and hydroperoxides, which
decrease value of these stabilizers at long photooxidation.
Tinuvine 770-bis (2, 2, 6, 6 - tetramenthylpiperidile - 4) sebacate, proposed by the firm
“CIBA” [71], and some polymer addititives, including fragments of piperidine cycle are used
in industry. As a rule, stabilizers, containing stable radical in their structure, are also
inhibitors of thermooxidative destruction.
Additions of amine stabilizers greatly increase thermal stability of PA at long ageing
[72]. For example, such antioxidants as N,N 1 - di - β - naphthyl - p - phenylene diamine;
N,N 1 , β - phenylcyclohexil - p - phenylene diamine; N,N 1 , β - diphenyl - p - phenylene
diamine and phenyl - β - naphthylamine conserve strength of PA - fibres by 70-95% at it
warming up for 2 hours at 200 0 C (unstabilized fibre - 22%). Despite high inhibitive activity
their use is limited, as intermediate products of their transformations dye polymer.
Good low-dyeing antioxidants are derivatives of 4 - oxidiphenylamine [73, 74], for
example, 2, 2 - (diphenylaminophenoxi) diethyl ether, known as stabilizer H-1; 2, 2
(naphthylaminophenoxi) diethyl ether [75]. They are used for thermal stabilization of PCA -
threads of technical purpose, though some produced forms of stabilizer H-1 initiate