The mesomorphous state of polyamic acids

Sidorovich, A. V.; Baklagina, Yu. G.; Stadnik, V.P.; Strunnikov, A.Yu.; Zhukova, T. I.

doi:10.1016/0032-3950(81)90330-0

Cited by 7 publications

(3 citation statements)

References 8 publications

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“…Therefore, it can be concluded that our samples are relatively rigid in the molecular direction. This is in agreement with the concept of a nematic structure of the PAA and PAA/C 60 systems, proposed by Sidorovich et al [25]. According to these authors, the creation of these structures in the PIs [25] takes place into two steps: (1) a mesophase formation in PAA concentrated solutions, (2) the improvement of the mesophase order, at 120-135 • C (thermal treatment previous to the imidization step).…”

Section: Final State Of the Pi/c 60 Compositessupporting

confidence: 80%

“…This is in agreement with the concept of a nematic structure of the PAA and PAA/C 60 systems, proposed by Sidorovich et al [25]. According to these authors, the creation of these structures in the PIs [25] takes place into two steps: (1) a mesophase formation in PAA concentrated solutions, (2) the improvement of the mesophase order, at 120-135 • C (thermal treatment previous to the imidization step). A subsequent heating at higher temperatures (imidization step) results in either the crystallization of the material or its transition to a better ordered mesophase.…”

Section: Final State Of the Pi/c 60 Compositessupporting

confidence: 80%

“…We have analyzed the percentage of area of this reflection with respect to the total WAXS area (S 11 ), as well as the crystal coherence length, D, derived from the integral width, and the variation of both quantities with temperature. Similarly to the case of other polyamic acids [25], the reflection at about 11 • may be related to the identity period of the polymeric chain. The variation of the degree of crystallinity observed during the thermal treatment exhibits a similar stepwise increase in both systems (see Fig.…”

Section: Downloaded By [University Of Chicago Library] At 17:07 17 Nomentioning

confidence: 94%

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Thermal imidization of polyamic acid–fullerene composites: 'in situ' X-ray diffraction study

Cagiao

Pozdnyakov

Krumova

et al. 2007

Composite Interfaces

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In situ' wide angle (WAXS) and small angle X-ray scattering (SAXS) studies were carried out to characterize the structural changes occurring during the conversion of a polyamic acid into the polyimide in the presence of fullerene, C 60 . The variations in crystallinity, long period, and the SAXS invariant of the samples are discussed in the light of the various temperature ranges studied. The conversion of the polyamic acid into the polyimide is analyzed according to the different structural steps. Results reveal that C 60 affects the degree of order of the composite in the molecular direction, giving rise to slightly smaller crystals than those found in pure polyamic acid. The difference in the SAXS data between the pure PAA and the composite are discussed through the interaction of C 60 molecules with the polyamic acid, which seems to hinder the imidization reaction up to 185 • C.

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Section: Final State Of the Pi/c 60 Compositessupporting

confidence: 80%

Section: Final State Of the Pi/c 60 Compositessupporting

confidence: 80%

Section: Downloaded By [University Of Chicago Library] At 17:07 17 Nomentioning

confidence: 94%

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