Schmelz‐ und kristallisationserscheinungen bei makromolekularen substanzen. IV. Haupt‐ und nachkristallisation von terylen aus dem glaszustand

Zachmann, Von H. G.; Stuart, H. A.

doi:10.1002/macp.1960.020410112

Cited by 101 publications

(21 citation statements)

References 12 publications

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“…Nach den vorgenannten Autoren l2, 13) wird daher der Kristallisationsablauf in zwei Vorgange aufgeteilt : in die Hauptkristallisation, diese beschreibt das Wachstum der morphologischen Einheiten, und in die Nachkristallisation, die eine Erhohung des Kristallisationsgrades der Einheiten selbst wahrend und auch nach AbschluB der Hauptkristallisation beschreibt. I m praktischen Falle wird die Hauptkristallisation immer von einer Nachkristallisation begleitet, die bei der Auswertung jedoch meistens vernachlassigt wird.…”

Section: Abb 2 Der Zeitliche Verlauf Des Kristallisationsgrades a Wunclassified

Kristallisation von Polycarbonaten. II. Dilatometrische Untersuchungen an Poly‐4,4′‐dihydroxidiphenyl‐2,2‐propan‐carbonat

Falkai¹,

Rellensmann²

1965

Makromol. Chem.

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ZUSAMMENFASSUNG:Die Gesamtkristallisation des Poly-4,4'-dihydroxidiphenyl-2,2-propan-carbonat wurde durch dilatometrische Messungen der h d e r u n g des spezifischen Volumens wahrend sehr langer Kristallisationszeiten bei Kristallisationstemperaturen von 170 bis 205 "C verfolgt.Eine w-esentliche Kristallisation tritt erst bei Kristallisationstemperaturen oberhalb von 175 "C ein. Dcr gefundene maximale Kristallisationsgrad betrug 33 %. Dieser wurde nach isothermer Kristallisation bei einer Kristallisationstemperatur von 205 "C unter Berucksichtigung partieller Schmelzvorglnge erreicht. 'Die sehr langen Kristallisationszeiten bestatigen die friiher diskutierte Kristallisationstragheit dieser Stoffklasse.Durch Auswertung der dilatometrischen Messungen nach der Theorie von AVRAMI wurden die Geschwindigkeitskonstanten k, und der Zeitexponent n in dem genannten Temperaturbereich bestimmt.Aus der lichtoptisch beobachteten athermischen Keimbildung und dem ermittelten Zeitexponenten n = 3 folgt, daB das Wachstum der Sphirolithe dreidimensional kugelformig verlauft.Die Messungen werden mit Ergebnissen anderer Untersuchungsmethoden verglichen. SUMMARY:The over-all crystallization of poly-4,4'-dihydroxydiphenyl-2,2-propane carbonate was observed by dilatometric measurements of the alteration of the specific volume during very long crystallization fimes a t crystallization temperatures of 170*to 205 "C.Appreciable crystallization does not take place before crystallization temperatures above 175 "C. have been reached. The maximum degree of crystallization found was 33 yo, which was reached after isothermal crystallization a t a crystallization temperature of 205 "C. taking due regard to partial processes of fusion. The very long times of crystallization confirm the crystallization inertness of this class of substances as didcussed earlier.Evaluating the dilatometric measurements according to AVRAMI'S theory, the velocity constants k,, and the time exponent n were determined in the mentioned range of temperatures. 38Kristallisation von Polycarbonaten. 11.It follows from the predetermined nucleation observed light-optically and from the time exponent n = 3 asdetermined that the growth of the spherulites takes place spherically in three dimensions.The measurements are compared with the results of other methods of investigation.

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Section: Abb 2 Der Zeitliche Verlauf Des Kristallisationsgrades a Wunclassified

Kristallisation von Polycarbonaten. II. Dilatometrische Untersuchungen an Poly‐4,4′‐dihydroxidiphenyl‐2,2‐propan‐carbonat

Falkai¹,

Rellensmann²

1965

Makromol. Chem.

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“…The mechanism of crystallization from the glassy state has been of much interest for a long time. The density change during crystallization was measured by Keller et al [1][2][3] and by Zachmann and Stuart [4]. Gfinther and Zachmann [5] studied the influence of catalysts on the kinetics of crystallization.…”

Section: Introductionmentioning

confidence: 99%

Influence of catalysts on the rate of crystallization and on the crystal distortions in poly(ethylene terephthalate)

Asano¹,

Dzeick-Pickuth²,

Zachmann³

1989

J Mater Sci

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The crystallization behaviour of poly(ethylene terephthalate) (PET) containing different amounts of catalysts as well as of PET without catalysts has been studied. The kinetics of crystallization from the glassy state has been investigated by time-resolved small-angle X-ray scattering employing synchrotron radiation. The degree of crystallinity and Ruland's lattice distortion factor k were measured by wide-angle X-ray scattering. The results show that not only calcium acetate but also manganese acetate acts as a nucleating agent in PET. If the crystallization takes place close to the glass transition temperature, the catalysts also influence the amount of lattice distortions: the larger the nucleating effect, the smaller the factor k. This is explained by the fact that, due to restricted motion of the molecules, the amount of lattice distortion of the crystals within a spherulite increases with increasing distance from the centre of the spherulite.

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“…The dual or multiple differential scanning calorimetry endothermic behavior observed in many semicrystalline polymers, such as high and low density polyethylenes [1] and polyethylene single crystals, [2] polycaprolactam and poly(hexamethylene adipamide), [3,4] poly(propylene), [3] poly(propylene oxide), [5] poly(4-methyl pentene-1) single crystals, [6] poly(ethylene terephthalate), [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] and poly(aryl ether ether ketone), [24 -41] which have been previously crystallized isothermally, has been the subject of intense activity in the field of polymer science and the subject of some controversy in the literature. In such cases, two endothermic fusion peaks appear in subsequent DSC heating scans; the low endotherm normally occurs at about 5-30 8C above the crystallization temperature, increases in magnitude and shifts to higher temperature with increasing annealing/crystallization temperature/ time, while the upper-temperature peak remains at a constant temperature.…”

Section: Introductionmentioning

confidence: 99%

“…Following the approaches of various workers on PET [15,18] and PEEK, [27] we have therefore carried out further experiments to check the above mentioned hypothesis for the case of PET/HBA/HQ/TPA copolyesters. In this paper, we would like to present experimental evidence, including supplementary differential scanning calorimetry, wide angle X-ray diffraction and density techniques, to show that hypothesis (ii) is more reasonable, on the basis of which we can readily account for the occurrence of the double endothermic peaks in DSC scans of PET/HBA/HQ/TPA copolyesters.…”

Section: Introductionmentioning

confidence: 99%

A Further Study on the Crystallization and Melting Behavior of Liquid Crystalline Copolyesters Based on Modified Poly[(p-hydroxybenzoic acid)-co-(ethylene terephthalate)]

Liu¹

2001

Macromol. Chem. Phys.

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In a previous investigation of the crystallization and melting behavior of liquid crystalline PET/HBA/HQ/TPA copolyesters, which were prepared by the incorporation of p‐hydroxybenzoic acid (HBA), hydroquinone (HQ), and terephthalic acid (TPA) into poly(ethylene terephthalate) (PET), we reported that they are more crystalline than PET/HBA copolyesters. Introduction of HQ/TPA disrupts longer rigid‐rod sequences formed by HBA, enhancing macromolecular motion and increasing crystallization rate and crystallinity. In particular, PET/HBA/HQ/TPA copolyesters may also exhibit two endothermic fusion peaks under certain crystallization conditions. This paper is a further study of the crystallization and melting behavior of a PET/HBA/HQ/TPA copolyester with molar ratio of 40/20/20/20. The double‐peak differential scanning calorimetry melting endotherms from isothermally‐crystallized samples have been scrutinized in terms of two hypotheses: (i) they are associated with two distinct morphologies or crystals; (ii) they are related to melting and recrystallization effects. Our data from a combination of differential scanning calorimetry, wide angle X‐ray diffraction, and density techniques support the second hypothesis, and are not consistent with the first one.

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Schmelz‐ und kristallisationserscheinungen bei makromolekularen substanzen. IV. Haupt‐ und nachkristallisation von terylen aus dem glaszustand

Cited by 101 publications

References 12 publications

Kristallisation von Polycarbonaten. II. Dilatometrische Untersuchungen an Poly‐4,4′‐dihydroxidiphenyl‐2,2‐propan‐carbonat

Kristallisation von Polycarbonaten. II. Dilatometrische Untersuchungen an Poly‐4,4′‐dihydroxidiphenyl‐2,2‐propan‐carbonat

Influence of catalysts on the rate of crystallization and on the crystal distortions in poly(ethylene terephthalate)

A Further Study on the Crystallization and Melting Behavior of Liquid Crystalline Copolyesters Based on Modified Poly[(p-hydroxybenzoic acid)-co-(ethylene terephthalate)]

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