STABILIZATION AND MODIFICATION OF POLYCAPROAMIDE - Photochemical Reactions in Heterochain Polymers - page 45

Figure 1.22 DTA curves in the air: I-undyed kapron; 2-kapron dyed by active golden yellow RCr
covalently linked; 3-kapron dyed by hydrolyzed golden yellow.
Еxoeffect at 210 0 C appears in initial sample before melting (endoeffect at 220 0 C),
which is probably connected with polymer crystallization being absent in dyed fibre.
May be this difference is connected with the fact that the dye is situated in amorphous
regions of PCA and is linked with functional groups by covalent bonds, which, as a result,
limits the possibility of polymer crystallization.
So, one may come to a conclusion that proposed dyes possess high light protective and
thermooxidative action.
Complex thermographic investigation of PCA-fibre samples, containing the dye linked
with polymer by both covalent forces (active dye-LXI) and chemosorption forces (hydrolyzed
form of the dye) - LXII has been carried out.
Kapron was dyed by dichlortriazine dye - LXI and its deactivated dioxytriazine form.
Dye content on the fibre did not exceed 1% from polymer mass.
The first small endoeffect, accompanied by a little mass loss within temperature range
80-90 0 C, is connected with the loss of absorbed moisture. Endoeffect at 203-218 0 C without
loss of weight corresponds to melting of PCA crystal regions. Further thermal effects are
connected with oxidative destruction of polymer. As it is seen from Figure 1.21, there are no
sharp differences in thermal effects both in initial and dyed PCA.
Quite another picture is observed during investigation of DTA curves, obtained in inert
atmosphere (Figure 1.22). Thermal effects of moisture loss and melting are observed
correspondingly at 80 and 210 0 C. If deep effect is observed in the air in temperature range
430-445 0 C, accompanied by loss of mass, then a number of endoeffects are observed in
argon in temperature range 420-480 0 C, also accompanied by loss of weight.