Scanning Nanocalorimetry at High Cooling Rate of Isotactic Polypropylene

Santis, Felice De; Adamovsky, Sergey; Titomanlio, G.; Schick, Christoph

doi:10.1021/ma052525n

Cited by 183 publications

(137 citation statements)

References 45 publications

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“…At cooling rates !150 C s À1 a shoulder at lower temperatures is observed, which indicates a transition to the mesomorphic phase of i-PP. These results are in agreement with literature [38]. At cooling rates higher than 800 C s À1 a fully amorphous polymer is obtained.…”

Section: Non-isothermal Fast Cooling Of Nucleated and Non-nucleated I-ppsupporting

confidence: 93%

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Fast cooling of (non)-nucleated virgin and recycled poly(propylenes): Effect of processing conditions on structural and mechanical properties

et al. 2015

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. Fast cooling of (non)-nucleated virgin and recycled poly(propylenes) : effect of processing conditions on structural and mechanical properties. Thermochimica Acta, 603, 94-102. DOI: 10.1016/j.tca.2014 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. A B S T R A C TIn this study, the effect of processing parameters, i.e., the cooling rate and pressure, on the structureproperty relationships for nucleated and non-nucleated i-PP from virgin and recycled sources was investigated. Special attention was given to the brittle-to-ductile transition of nucleated i-PP from plastic packaging waste. Differential fast scanning calorimetry and dilatometry were used to mimic industrial process conditions. From the calorimetric experiments, it was observed that under ambient pressure the mesomorphic phase was formed upon fast cooling, which was confirmed by WAXD analysis. The dilatometry results showed that by applying pressure also g-phase crystals are formed. Nucleated samples showed an increased tendency for the g-phase formation and a decreased tendency for mesomorphic phase formation. Up to now, recycled i-PP showed a brittle behavior, but this study showed that by applying a sufficiently high cooling rate, the yield stress can be reduced and a stabilization of the deformation can be obtained leading to a ductile behavior for recycled i-PP.

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Section: Non-isothermal Fast Cooling Of Nucleated and Non-nucleated I-ppsupporting

confidence: 93%

“…All contribute to a lower yield stress. On laboratory scale, the formation of these phases can be investigated by dilatometry and differential fast scanning calorimetry [20,28,38,39]. This type of DSC instrument allows the use of extremely high heating and cooling rates and is ideal for the investigation of metastable structures.…”

Section: Introductionmentioning

confidence: 99%

Fast cooling of (non)-nucleated virgin and recycled poly(propylenes): Effect of processing conditions on structural and mechanical properties

et al. 2015

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“…We have to remark here that the proposed approach is valid only in the case of limited cooling rates, because at very high cooling rates the formation of nuclei is suppressed also, which can be seen in the work of Boyer et al 32 or van Drongelen et al 34 . In addition the proposed model could not be tested also in the case if crystallization takes place in the vicinity of glass transition temperature (Tg), because it requires special fast scan calorimetry to perform such experiments 46 . Accordingly, the extension of this calculation approach to extreme fast cooling rates could be the direction of further studies.…”

Section: G(t) Was Calculated For All These Temperatures After All G(mentioning

confidence: 99%

Determination of Nucleus Density in Semicrystalline Polymers from Nonisothermal Crystallization Curves

et al. 2015

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The present study introduces a new calculation method for obtaining nucleus density formed during non-isothermal crystallization of semicrystalline polymers. Isotactic polypropylene homopolymer (iPP) was used as a semicrystalline model polymer and its crystalline structure was modified using highly efficient nucleating agents or different cooling rates in order to manipulate nucleus density (N) within a wide range. The melting and crystallization characteristics were studied by calorimetry (DSC) and the nucleus density was calculated from the crystallization curves recorded under nonisothermal conditions at constant cooling rate. The nucleus density was correlated to the optical property, in fact to the haze index of injection molded plaques in order to qualify the calculated values of N. It was found that N increases more orders of magnitude in nucleated samples and correlates strongly to the optical properties. These observations are according to our expectations and indicate clearly the reliability of the proposed calculation approach.

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“…The molecular weight distribution was determined by a size exclusion chromatography, with weight-average molar mass Mw of 376 kg mol -1 , polydispersity index M w /M n of 6.7, and a meso-pentads content 87.6%. The glass transition temperature (T g ) and the nominal melting temperature of Moplen T30G i-PP are -15 °C and 166 °C, respectively [1][2][3].…”

Section: Methodsmentioning

confidence: 99%

Spherulitic nucleation and growth rates in a sheared polypropylene melt

Santis¹,

Scermino²,

Pantani³

et al. 2014

AIP Conference Proceedings

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In common polymer processing operations such as injection molding, film blowing, and fiber spinning, the molten polymer is subjected to intense shear and/or elongational flow fields and crystallizes during or after the application of flow. The semicrystalline morphology that develops in the final product is typically very different from what is observed during quiescent crystallization of the same polymer, and the properties change accordingly. The possibility of controlling the final morphology and the resulting mechanical and functional properties of semicrystalline polymers based on the study of polymer melt crystallization stimulated by flow is highly intriguing. This work starts from the experimental evidence that there exists qualitatively three regimes of crystallization under shear: (a) very low shear rates, in which there is no effect on kinetics; (b) higher shear rates, in which orientational effects enhance just the nucleation and growth rates, and spherulitic crystallization is observed; and (c) high shear rates, in which molecular stretching occurs giving rise to a fibrillar morphology development under very fast kinetics. The first two regimes are explored and analyzed by means of experimental protocols developed on purpose. In particular: -spherulitic nucleation and growth rates under continuous shear rates were carefully measured and related to molecular strain -the condition below which crystallization turns out to be essentially quiescent was evidenced.

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Scanning Nanocalorimetry at High Cooling Rate of Isotactic Polypropylene

Cited by 183 publications

References 45 publications

Fast cooling of (non)-nucleated virgin and recycled poly(propylenes): Effect of processing conditions on structural and mechanical properties

Fast cooling of (non)-nucleated virgin and recycled poly(propylenes): Effect of processing conditions on structural and mechanical properties

Determination of Nucleus Density in Semicrystalline Polymers from Nonisothermal Crystallization Curves

Spherulitic nucleation and growth rates in a sheared polypropylene melt

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