Über den Einfluß von Wasser auf die Polymerisation von Hexachlorcyclotriphosphazen

The behavior of poly[bis(trifluoroalkoxy)phosphazene] (PBFP) has been studied from 25 to 250 "C approximately by investigating the influence of temperature and cycle time upon creep compliance, volume change, spherulitic morphology, birefringence, and thermal properties. Unfractionated PBFP samples of high and low molecular weight were studied. The effect of aging upon properties, especially through the mesophase transition T(l), were examined. Noticeable differences in mechanical behavior were observed depending upon the history or state of the sample. Hysteresis in the transition temperature determined by differential scanning calorimetry, creep compliance measurements, and dilatometry was observed. The curves of reduced densification and hardening due to aging measured dilatometrically and in creep, respectively, were superposable. Thus the decreases in volume and compliance appear to be mutually proportional to the degree of mesophase transformation from the 2D to the 3D crystalline state. This change can be described by a growth process with a E nucleation parameter of 680 K. This value is high compared to that observed in ordinary polymeric crystallization. Well-defined negatively birefringent spherulite films were obtained in solution-cast films. Melt-crystalliied f i s usually contained needlelike aggregates of well-oriented crystals.Whenever PBFP specimens are heated through T(1) the X-ray diffraction patterns degenerate to a single reflection, suggestive of a pseudohexagonal crystalline modification, which persists between T(l) and T,. The optical retardation measured within a single spherulite increases noticeably upon heating through this transition. However, afterward it remains invariant until the sample is heated to ita true melting temperature when the birefringence finally reaches zero. Whenever the sample is melted, the spherulitic structure is lost.

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“…Figure10. log (creep compliance), (JA) (cm2/dyn) vs. temperature (°C) for heating and cooling of samples 1 and 2.…”

mentioning

confidence: 99%

Physical properties of polyphosphazenes. 2. Poly[bis(trifluoroethoxy)phosphazene]

Masuko¹,

Simeone²,

Magill³

et al. 1984

Macromolecules

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“…Poly(dialkoxyphosphazenes) (−[NP(OR) 2 −] n −) with alkoxy substituents OR = OC 3 H 7 , OC 4 H 9 , OC 5 H 11 (designated as PDAP-C3, PDAP-C4, and PDAPC5, respectively), were prepared and kindly provided by Dr. Dzidra Tur. Their synthesis was described in detail earlier; − the digest is provided in the Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

Kinetics of Inverse Melting/Crystallization of Poly(dialkoxyphosphazenes)

Папков

Бузин

Bukalov

et al. 2019

Crystal Growth & Design

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We have carried out a study of an unusual phase behavior of poly(dialkoxyphosphazenes) with pentoxy, butoxy, and propoxy substituents forming columnar mesophases which undergo a reversible transition into amorphous rubberlike state on cooling and reverse conversion into the original mesophases upon subsequent heating. On heating to around 200 °C they also yield isotropic melts. The DLI technique and polarized light microscopy were used for monitoring the overall rate of inverse 2D crystallization and linear growth rate of mesomorphic lamellae. The obtained kinetic data were treated in the framework of the Avrami approach and classical nucleation-controlled crystallization theory. Summarizing the results of our optical studies, we have concluded that the formation of 2D columnar mesophases in PDAP-C(3÷5) both in the usual way from the isotropic melt on cooling and via inverse freezing (crystallization) on heating the low-temperature reentrant amorphous phases is induced by heterogeneous athermal nuclei growing in two dimensions and yielding eventually a lamellar mesophase morphology.

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Investigation on the formation of polychlorophosphazene branchings at different units of the polymer chain (in Russian)

Koršak¹,

Vinogradova²,

Tur³

et al. 1980

Acta Polymerica

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Ausgehend von der Anwesenheit von Amido‐ und Imidoendgruppen im Polychlorphosphazen werden die Nebenreaktionen erörtert, die zur Bildung verzweigter Makromoleküle bei der thermischen Schmelzepolymerisation führen. Es wurde der Einfluß solcher Faktoren wie Restwasser im Polymerisationssystem, HCl‐Menge, Grad der Ampullenfüllung und Polymerisationszeit bei 250°C auf die chemische Uneinheitlichkeit des gebildeten Polychlorphosphazens untersucht. Es wurde gezeigt, daß eine Änderung dieser Bedingungen eine bewußte Steuerung der Bildung verzweigter chemisch uneinheitlicher Makromoleküle ermöglicht.

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Über den Einfluß von Wasser auf die Polymerisation von Hexachlorcyclotriphosphazen

Cited by 12 publications

References 12 publications

Physical properties of polyphosphazenes. 2. Poly[bis(trifluoroethoxy)phosphazene]

Physical properties of polyphosphazenes. 2. Poly[bis(trifluoroethoxy)phosphazene]

Kinetics of Inverse Melting/Crystallization of Poly(dialkoxyphosphazenes)

Investigation on the formation of polychlorophosphazene branchings at different units of the polymer chain (in Russian)

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