STABILIZATION AND MODIFICATION OF POLYETHYLENETEREPHTHALATE - Photochemical Reactions in Heterochain Polymers - page 141

Figure 3.18. Kinetic curves of mass loss in isothermal conditions (240ºC) of PETP - fibres: 1 - undyed;
2 - modified by HC-1; 3 - modified by HC-2; 4 - modified by HC-3; 5 - modified by HC-4; 6 -
modified by HC-5; 7 - modified by HC-6; 8 - modified by HC-7.
During addition of HC-3 and HC-4 such effect is not observed, probably these additives
have inhibiting effect on thermal and thermooxidative destruction, as these additives do not
have developed chain of conjugation. Taking into account the fact that polymer materials
must work in narrow temperature ranges for a long time, we have studied also kinetics of
thermal destruction at isothermal heating.
Data of kinetics of mass loss at samples warming up in the air at 200ºC are given in
Figure 3.18, from which it is seen that introduction of hexaazocyclanes into PETP decreases
mass loss of polymer. Since for the period of 5 hours unmodified PETP - fibre loses about
5%, while PETP - fibres, modified by hexaazocyclanes, lose weight much less under the
same conditions. For example, the fibre, modified by the dye HC-2, loses 0,8% of the weight.
As at differential - thermal analysis HC-3 and HC-4 additives cause the increase of the rate of
polymer mass loss.
From Figure 3.19 it is seen that introduction of hexaazocyclanes increases thermal
stability of PETP in the air, moreover it depends on the chemical structure of additive and,
specifically, on the degree of conjugation in molecule. As it is seen mass loss of unmodified