STABILIZATION AND MODIFICATION OF POLYETHYLENETEREPHTHALATE - Photochemical Reactions in Heterochain Polymers - page 121

Literature survey has shown, that there are no data on the effect structure of
introducticing modifiers on physico-chemical properties of polymer and also in what classes
of chemical substances it is necessary to search for potential light-thermal stabilizers.
As it is shown earlier, effective additives-modifiers of polyfunctional action may be
compounds, containing conjugated systems (CS) with high degree of conjugation.
Hexaazocyclanes (HC), having developed conjugation chain, high photo and thermal
stability, have been chosen as the objects of investigation. Presence of chromophore groups
allows to use them in addition as polymer dyes.
Compounds, presented in Figure 3.1, were synthesized on the basis of phthalodimitrile
(1); π-phenyldiamine (2) and derivatives of diaminefluorene (3). In order to check the effect
of macrocyclic stabilizer structure on HC properties there were studied substances being the
products of condensation of phthalodinitrile (1) with m-phenyldiamine (4).
Chemical structures of chosen hexaazocyclanes differ in degree of conjugation.

NH 2

NH 2

C =

C

C =

NH 2

NH 2 NH 2 NH 2

(1)

(2)

(4)

(3)

Characteristics of obtained compounds are given in Table 27.

Table 27. Characteristics of hexaazocyclanes

Conventional
sign

Medium
molecular mass

λ max , nm
(solvent acetone)

Melting
T, 0 C

Decay
T, 0 C

Colour of the
dye

HC-1 600 360 305 330 yellow

HC-2 580 380 327 345 lemon

HC-3 670 340 315 327 yellow

HC-4 454 400 345 330 beige

HC-5 554 330 335 365 yellow

HC-6 552 360 327 350 beige

HC-7 538 330 300 347 light-brown

Electronic absorption spectra of compounds being used contain absorption band with
λ max =330-400 nm (Figure 3.2).
Criteria of compounds thermal stability are temperature values: melting, beginning of
decay and losses of system initial mass at differential-thermal analysis (DTA) by 5, 10, 25%.
These data are given in Table 28.
As it is seen from Table 28 all the compounds under investigation possess high thermal
stability, exceeding greatly thermal stability of PETP. Temperatures of melting and beginning