Chemistry Reference
In-Depth Information
Deformation of polymer material, which, in the first place, affects amorphous regions,
takes place during its mechanical loading. First, there occur conformational transformations
of passing molecules, and then, when reserve of their conformations is being partly
exhausted, there begins mechanical deformation of valence angles and chemical bonds with
their further break.
Thus, amorphous regions of polymer, bounded by crystals, are “macroreactors” in which
chain process of mechanodestruction and failure of material is being developed. Hence,
decrease of the amount of polymer amorphous part will lead to strengthening of the fibre and
improving its physico-mechanical characteristics.
Method of microphotography was used to study polymer structure and effect of additives
HC-1 - HC-7 introduction. Microphotography of polymer fibres shear was carried out with
the help of microscope “Polar”, at enlargement by 40 times, the microscope had special
extension for photography. Photoes of dyed and undyed fibres and also photos of their
longitudinal shears are given in Figure 3.4. - 3.10.
From the analysis of microphotoes it follows that introduction of hexaazocyclanes does
not disturb uniformity of polymer structure that shows good solubility of hexaazocyclanes in
PETP melt. On the basis of the technique [167, 296] according to microphotoes there has
been performed calculation of heterogencous embedding of additives into fibre which gives
the value 125 units per kilogram, which is lower than 300 units per kg permissible by State
standard. This shows the uniformity of additive distribution in polymer.
Microphotoes of initial PETP - fibre and its cross-section are given in Figure 3.4. Two
regions - amorphous and crystalline - are observed in the photo of cross - section of initial
PETP fibre (Figure 3.4 b). Lamellar and fibrillar formations are seen in crystalline regions,
but they are not quite developed. Amorphous part occupies large volume of the general
polymer space.
Microphotoes of PETP - fibres, modified by HC-1 - HC-6 and their cross-sections are
shown in Figure 3.5. - 3.10. Comparing microphotoes of initial and modified PETP it should
be noted that modified PETP displays large tendency to crystallization.
Lamellar and fibrillar formations are seen in the photos of fibres dyed by HC-1, HC-3,
HC-4 (Figure3.5, 7, 8), moreover these formations are large in dyed fibres than in initial
PETP.
Tendency to crystallization in fibres with additives HC-2, HC-5, HC-6 increases still
more. Radial spherulite formations of rather large size are observed in microphotoes of fibres
modified by these hexaazocyclanes (Figure 3.6, 9, 10).
Two processes of formation of new phase nucleus and further growth of already present
ones take place at the moment of crystallization. Nuclei formation is the first act of
nucleation.
In molten state PETP consists of associates which may be the cores of formation of
crystallization nuclei. Completion of crystallization process and crystal size depend very
much on rates chains lay-up on the side of growing crystal and relaxation of large segments
relation.
Increase of modified PETP ability to crystallization compared with unmodified PETP, as
we see it, is connected with the fact that hexaazocyclanes play the role of singular centres of
crystallization. This causes change of molecular orientation in the fibre at the moment of
formation, when supermolecular structure begins to organize. And here new more regulated
structure is being formed and this agrees with conclusions of the works [130,297].
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