Experimental study of crystallization of PolyEtherEtherKetone (PEEK) over a large temperature range using a nano-calorimeter

Tardif, Xavier; Pignon, Baptiste; Boyard, Nicolas; Schmelzer, Jürn W. P.; Sobotka, Vincent; Delaunay, Didier; Schick, Christoph

doi:10.1016/j.polymertesting.2014.03.013

Cited by 108 publications

(87 citation statements)

References 43 publications

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“…So the β-transition of branched PEs was greatly dependent on the DB, as the content of amorphous structure proves. The results of this work agree with Tardiff et al 27 which showed that the DB has influence in lamellar thickness and amorphous-layer thickness and is the main contributor to secondary process resulting in a higher deviation of the Avrami equation.…”

supporting

confidence: 92%

“…It must be taken into account that in nonisothermal crystallization, the values of k and m do not have the same physical significance as in the isothermal crystallization, due to the fact that under nonisothermal conditions the temperature changes constantly. So, m and k, are two adjustable parameters to be fit to the data [17,27].…”

Section: Materials and Methods:-mentioning

confidence: 99%

“…From each region different values for m (m 1 and m 2 ) and k (k 1 and k 2 ) were obtained. The exponent m 2 might correspond to the formation of new and a more stable lamellae as a result of the lamella-thickening effect 27 , i.e., the possibility of lamella thickening was the main contributor to the secondary process 28 , however the plots for polypropylene and polyethylene waxen didn´t show this phenomenon. The values of the rate constants k and Avrami exponent m as a function of the cooling rate for the materials used by Equation (3) are listed in Table 2.…”

mentioning

confidence: 99%

“…These values have different implications for the growth mechanisms; m 1 ≈ 4 corresponds to the three dimensional spherical growth and thermal nucleation in the primary crystallization stage, it also indicates the dominant super-structural morphology is spherulitic and that nucleation is near instantaneous 15,27 ; m 2 ≈ 2 correspond to the one-dimensional linear growth and thermal nucleation during the secondary stage and the changing values of k indicate the variation of dominance of two competing nucleating and growth processes as have been reported in literature on this subject 1,19,20,29 .…”

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confidence: 99%

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Avrami Model Deviations in Polyolefins as Function of the Complexity of the Molecular Structures.

Blanco¹,

Cisneros²,

Belmonte³

et al. 2017

IJAR

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The influence of the complexity of the molecular structure and the cooling rate in the Avrami model fitting has been studied. Kinetics of non-isothermal crystallization of polypropylenes (with different molecular weights), polyethylenes (High Density Polyethylene, HDPE and Low Density Polyethylene, LDPE) and polyethylene wax from molten state were performed under non-isothermal conditions at cooling rates of 3, 10, and 50 °C min -1 . Differential scanning calorimetry (DSC) was used to monitor the crystallization. The results showed that the predicted evolution of relative crystallinity using the Avrami model was a better fit for the polypropylenes and polyethylene waxen than for the polyethylenes due to their molecular structure much more simple and regular. The fitting for higher cooling rates was better than for lower cooling rates for all the materials analyzed and this could be attributable to a predominant homogeneous nucleation at higher cooling rates and predominant heterogeneous nucleation at lower cooling rates. The fitting for HDPE was better than for LDPE at the final stage of crystallization for various cooling rates due to the phenomenon of a slower secondary crystallization. The results showed a better fitting of the Avrami equation for the polypropylenes and polyethylene waxen than for the polyethylenes due to the influence of the branching degree in lamellar thickness and amorphous-layer thickness as the main contributor to secondary process.

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supporting

confidence: 92%

Section: Materials and Methods:-mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Avrami Model Deviations in Polyolefins as Function of the Complexity of the Molecular Structures.

Blanco¹,

Cisneros²,

Belmonte³

et al. 2017

IJAR

View full text Add to dashboard Cite

show abstract

“…Thermal properties and contact angle of the pure APE and APE/TiO 2 nanocomposites with 1, 3, 5% TiO 2 and 5% TiO 2 W/C. 0 113 122 6 29 96 51 393 434 58 1 105 118 4 22 92 43 392 434 64 3 115 124 10 9 93 34 393 433 65 5 109 118 6 14 91 39 393 432 69 5 W/C 93 104 3 15 82 31 178 476 nd nd= not determine (PEEK) 29 , poly (ethylene terephthalate) (PET) 25 , among others and can be explained by the formation of different morphologies associated with the crystallization process of these polymers. These materials can present two or more crystal modifications or, at least two groups with various lamellar structures, or even different crystalline morphologies 25 .…”

Section: Characterization Of the Ape/tio 2 Nanocompositesmentioning

confidence: 99%