Cited by 82Polymer crystallization and propertiesbiodegradable polymer synthesis and propertiesnanoparticles nucleation surface interactions

Heterogeneous Nucleation and Self-Nucleation of Isotactic Polypropylene Microdroplets in Immiscible Blends: From Nucleation to Growth-Dominated Crystallization

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Wang, Bao, Utzeri, Roberto, Castellano, Maila, Stagnaro, Paola, Müller, Alejandro J., Cavallo, Dario·2020·Macromolecules

Abstract

Nucleating agents (NAs) are widely used for speeding up processing and tuning the final optical and mechanical properties. Despite their industrial importance, the search for highly efficient NAs is still mainly empirical. In this work, the heterogeneous nucleation process of isotactic polypropylene (i-PP) droplets containing nucleating agents (i.e., sodium benzoate (SB), (4,6-di-tert-butylphenyl)phosphate (NA-11), quinacridone quinone (QQ)) dispersed in an immiscible polystyrene matrix has been studied by differential scanning calorimetry (DSC) using an isothermal step crystallization protocol. When semicrystalline polymers are confined into isolated micro- or nanodomains, nucleation can kinetically control the overall crystallization. Differently, in a bulk polymer, the contributions of the nucleation and growth steps to the overall crystallization rate are commonly of similar importance. In the studied system, it is shown for the first time that the crystallization of nucleated i-PP droplets exhibits a first-order kinetics, with characteristic times much larger than those required for the crystals to grow and occupy the whole microdomain volume. Therefore, the kinetics of heterogeneous nucleation can be directly assessed. On the contrary, when neat i-PP droplets are self-nucleated, the crystallization kinetics shows a sigmoidal trend, with times comparable to those for the crystal space filling. This indicates the absence of any primary nucleation barrier for ideally self-nucleated PP melts, or at least that this nucleation barrier is negligible in comparison to the one for secondary nucleation/crystal growth. For the first time, it is evidenced that, as long as nucleation is the rate-determining step in the overall crystallization kinetics, a first-order kinetics can be obtained for both homo- or heterogeneously nucleated droplets in immiscible blends. A novel way to calculate an "intrinsic"nucleation efficiency, based on the derived free-energy barriers of the different NAs, is proposed. This fundamental knowledge of heterogeneous nucleation can serve as a tool for a more rational search for new nucleating agents and can provide a method to unambiguously identify the origin of multiple-crystallization exotherms in fractionated crystallization of immiscible blends.

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Crossref · 10.1021/acs.macromol.0c01167

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73 of 73 references verified0 citation errors · 0 not checkable

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  • Equation 6 has been applied to describe crystallization kinetics of several immiscible blends with droplet morphology, namely PS/PA6, compatibilized ethylene/1-octene copolymer/PA6, and neat and nucleated PS/iPP blends.

    “In the literature, Equation 6has been applied to describe the crystallization kinetics of several immiscible blends with droplet morphology, namely PS/PA6 [34] , compatibilized ethylene/1-octene copolymer/PA6 [35] , and more recently neat and nucleated PS/iPP blends [7] .”

    From Fractionated crystallization in semicrystalline polymers (2021) · cites this paper as [7]

  • Wang et al. demonstrated that first-order kinetics can also be associated with heterogeneously nucleated droplets.

    “More recently, Wang et al. demonstrated that a firstorder kinetics can also be associated with heterogeneously nucleated droplets [7] (see section 3.1 ).”

    From Fractionated crystallization in semicrystalline polymers (2021) · cites this paper as [7]

  • Crystallization of iPP micro-droplets containing 0.25 wt% NA-11 showed first-order kinetics with Avrami index around 1.0, suggesting heterogeneous nucleation was the rate-determining step for the entire crystallization process.

    “Crystallization of iPP micro-droplets containing 0.25 wt % NA-11 showed a first-order kinetics with Avrami index around 1.0, suggesting that heterogeneous nucleation was the rate-determining step for the entire crystallization process.”

    From Fractionated crystallization in semicrystalline polymers (2021) · cites this paper as [7]

  • All iPP droplets nucleated on known or unknown heterogeneities exclusively showed nucleation-controlled first-order kinetics.

    “All the iPP droplets nucleated on known or unknown heterogeneities (e.g., NAs, PS surface or type B heterogeneities) exclusively showed a nucleation controlled first-order kinetics, which can be further analyzed based on the classical heterogeneous nucleation model [343] to derive the interfacial free energy difference, σ , between the heterogeneities and the crystallizing polymer.”

    From Fractionated crystallization in semicrystalline polymers (2021) · cites this paper as [7]

  • Among all alpha-form crystal nucleating agents, NA-11 is the most efficient to nucleate iPP, exhibiting the lowest sigma.

    “It can be seen that, among all the α form crystal nucleating agents, NA-11 is the most efficient one to nucleate iPP, exhibiting the lowest σ .”

    From Fractionated crystallization in semicrystalline polymers (2021) · cites this paper as [7]

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Authors
Wang, B., Utzeri, R., Castellano, M., Stagnaro, P., Müller, A. J., & Cavallo, D.
Affiliations
  • University of Genoa (IT)
  • National Research Council (IT)
  • Ikerbasque (ES)
Corresponding author
  • Müller, Alejandro J.
  • Cavallo, Dario
Venue
Macromolecules
Published
2020-07-16
Volume
53
Issue
14
Pages
5980-5991
ISSN
  • 0024-9297 (ISSN-L)
  • 1520-5835
OpenAlex
W3042684120
Cited by
82
References
75
Citations by year
2026: 8 · 2025: 18 · 2024: 20 · 2023: 12 · 2022: 15 · 2021: 8 · 2020: 1
FWCI
3.41
Type
journal article
Language
en
Open access
Locations
  • Macromolecules (publishedVersion, cc-by)
  • CINECA IRIS Institutial Research Information System (University of Genoa) (submittedVersion)
  • INFM-OAR (INFN Catania) (submittedVersion, cc-by)
Funders
  • Eusko Jaurlaritza (IT1309-19)
  • China Scholarship Council
Topics
  • Physical Sciences › Materials Science › Polymers and Plastics › Polymer crystallization and properties
  • Physical Sciences › Materials Science › Biomaterials › biodegradable polymer synthesis and properties
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › nanoparticles nucleation surface interactions
Keywords
heterogeneous nucleation, self-nucleation, isotactic polypropylene, microdroplets, immiscible polymer blends, nucleating agents, polymer crystallization, nucleation efficiency

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