Dilatometric measurements on some polymers: The pressure dependence of thermal properties

Leute, U.; Dollhopf, W.; Liska, E.

doi:10.1007/bf01384021

Cited by 32 publications

(15 citation statements)

References 16 publications

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“…Our value at atmospheric pressure is in agrement with most literature data as discussed in 3.1. Secondly, our samples are about 20 times bigger than those in the previous investigations [1,2,6,27] which means a far better accuracy if the absolute accuracy to measure the length is the same in both cases. As a consequence of the differences of the functions…”

Section: Melting Of Modification I At High Pressurementioning

confidence: 87%

“…the discussion in ref. [1]), for the melting temperature and the procedure of sample preparations -which in our experience is equivalent to annealing -make the existence of sufficiently large crystals probable [23]. Compared to pressure dilatometry the diluent method [20] gave low values in the case of polypropylene too (cf.…”

Section: Melting Of Modification I At Low Pressurementioning

confidence: 91%

“…The high pressure dilatometers, described in more detail in [1,2], are piston-cylinder devices of 6 mm and 22 mm diameter respectively. The former attains a pressure of about 2 kbar, measured in the sample, but not controlled.…”

Section: Apparatusmentioning

confidence: 99%

“…In this series one of our aims is to provide -besides accurate p VT-data -information about the influence of pressure on phase transitions. The first five papers dealt with PE [1,3,4], PEO [1], PP [1,2], poly(trans-l,4-butadiene) [5] and n-alkanes [4]. Now we have chosen poly(1-butene), (-CH2-CHC2Hs-),, subsequently called simply polybutene, as the topic of the present study for the two following reasons.…”

Section: Introductionmentioning

confidence: 98%

“…The present publication is the sixth in a series of papers [1][2][3][4][5] on condensed polymers dealing with high pressure dilatometry. In this series one of our aims is to provide -besides accurate p VT-data -information about the influence of pressure on phase transitions.…”

Section: Introductionmentioning

confidence: 98%

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High pressure dilatometry on polybutene-1

Leute

Dollhopf

1983

Colloid & Polymer Sci

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High pressure dilatometry is used to study the melting processes and the melt of isotactic polybutene-1. Evaluating a great number of isobaric V(T)-curves determined in the range of a few hundred bar the pressure dependence of the melting temperature is accurately determined for modifications I and II.Extrapolation to 1 bar yields dTJdp = 43.6 K/kbar and a heat of fusion AHm=8.0 kJ/ mol for modification I. The values for modification II are 21.4 and 6.9 resp. Up to 4.25 kbar data of melting temperature, volume, entropy and enthalpy as a function of pressure are reported and also the compressibility of the melt. Finally the relative thermodynamic stability of the different modifications is discussed.

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Section: Melting Of Modification I At High Pressurementioning

confidence: 87%

Section: Melting Of Modification I At Low Pressurementioning

confidence: 91%

Section: Apparatusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

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High pressure dilatometry on polybutene-1

Leute

Dollhopf

1983

Colloid & Polymer Sci

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The continuous cooling transformation (CCT) as a flexible tool to investigate polymer crystallization under processing conditions

et al. 2009

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An experimental route for investigating polymer crystallization over a wide range of cooling rates (from 0.01 to 1000◦C/s) and pressures (from 0.1 to 40 MPa) is illustrated, using a method that recalls the approach adopted in metallurgy for studying structure development in metals. Two types of experimental setup were used, namely an apparatus for fast cooling of thin films (100–200 μm thick) at various cooling rates under atmospheric pressure and a device (based on a on-purpose modified injection molding machine) for quenching massive samples (about 1–2 cm3) under hydrostatic pressure fields. In both cases, ex situ characterization experiments were carried out to probe the resulting structure, using techniques such as density measurements and wide-angle x-ray diffraction (WAXD) patterns. The cooling mechanism and temperature distribution across the sample thickness were analyzed. Results show that the final structure is determined only by the imposed thermal history and pressure. Experimental results for isotactic polypropylene (iPP), poly(ethylene terephthalate) (PET), polyamide 6 (PA6), and syndiotactic polystyrene (sPS) are reported, showing the reliability of this experimental approach to assess not only quantitative information but also a qualitative description of the crystallization behavior of different classes of semicrystalline polymers. The present study gives an opportunity to evaluate how the combined effect of the cooling rate and pressure influences the crystallization kinetics for various classes of polymer of commercial interest. An increase in the cooling rate translates into a decrease in crystallinity and density, which both experience a sudden drop around the specific “crystallizability” (or “critical cooling rate”) of the material examined. The exception is sPS where competition among the various crystalline modifications determines a minimum in the plot of density vs. cooling rate. As for the effect of pressure, iPP exhibits a “negative dependence” of crystallization kinetics upon pressure, with a decrease of density and degree of crystallinity with increasing pressure, owing to kinetic constraints. PA6 and PET, on the other hand, due to thermodynamic factors resulting in an increase in Tm with pressure, exhibits a “positive dependence” of crystallization kinetics upon pressure. Finally, recent original results concerning sPS have shown that the minimum in the density vs. cooling rate curve shifts toward larger cooling rates upon increasing pressure

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Flow‐induced crystallization of polylactide stereocomplex under pressure

Song

Zhao

Yang

et al. 2018

J of Applied Polymer Sci

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Although shear and pressure fields always coexist in practical polymer processing, their combined influence on the crystallization behavior of polylactide stereocomplex (SC) is ambiguous due to the limit of experiment device. In that case, a homemade device was employed to prepare samples under the coexistence of shear and pressure and explore the crystallization behavior of SC. Differential scanning calorimetry and synchrotron radiation were used to investigate the combined effect of shear flow and pressure on SC crystallization. The results show that shear flow was helpful for SC formation. Shear flow promoted the phase mixing of the polymer blends and improved the nucleation efficiency of SC. Pressure had a negative effect on SC formation because of the decrease in free volume. Regard to polylactide homogeneous (HC), pressure played a positive role on HC formation. Pressure suppressed the formation of SC network which could impede HC generation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46378.

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Dilatometric measurements on some polymers: The pressure dependence of thermal properties

Cited by 32 publications

References 16 publications

High pressure dilatometry on polybutene-1

High pressure dilatometry on polybutene-1

The continuous cooling transformation (CCT) as a flexible tool to investigate polymer crystallization under processing conditions

Flow‐induced crystallization of polylactide stereocomplex under pressure

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