Chemistry Reference
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Figure 3.11. View of DTA curves for unmodified (1) and modified by HC-1 (2) and HC-2 (3) PETP -
fibres.
Endothermic process in region A runs beginning from 70 ºC and consists in transition of
polymer from glassy into elastic state without phase transformation - the process of
devitrification (at cooling - vitrification). Mobility of segments of polymer chains in polymer
amorphous regions appears in the range of vitrification temperature. Intensity of movement in
polymer amorphous regions decreases with the increase of crystallinity. Mobility of molecule
parts, situated in amorphous regions, is limited at the expense of the fact that other parts are a
part of crystalline region. Another reason for decrease of molecules mobility in amorphous
phase is probably stress which the fibre is probably subjected to.
Exothermic process of phase transition - crystallization, characterized by peak in the
region Б at the temperature 143 ºC runs after PETP devitrification.
The second endothermic process (region B) is observed at the temperature higher 230 ºC
and ends at 270 ºC. And during this process crystalline structure breaks and polyester melts.
This transition, as crystallization, is phase. High temperature of PETP melting is described by
specific role of aromatic nucleus linked by p - para-position [245].
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