A novel approach to the study of extensional flow-induced crystallization

Amirdine, Juliana; Htira, Thouaiba; Lefèvre, Nicolas; Fulchiron, René; Mathieu, Nathalie; Zinet, Matthieu; Sinturel, Christophe; Burghelea, Teodor; Boyard, Nicolas

doi:10.1016/j.polymertesting.2021.107060

Cited by 4 publications

(5 citation statements)

References 42 publications

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“…Many other efforts have also been done to understand FIC behavior. 13,23,34,[103][104][105][106][107][108][109][110] After decades of research, four distinctive features of FIC have been identified: (i) accelerated nucleation; (ii) preordered or mesophase; (iii) induced transition from lamellar to shish; (iv) induced new crystal structure. 22,49,111,112 There has been a lot of great reviews on the above four aspects.…”

Section: Methodsmentioning

confidence: 99%

Recent progress in flow‐induced polymer crystallization

Nie

Fan

Cao

et al. 2022

Journal of Polymer Science

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During industrial processing, such as film blowing and injection molding, semicrystalline polymers have to be subjected to external flow. Flow changes the nucleation rate, crystal morphology and polymorphism of polymers. As flow can be tunable, polymeric products with different macroscopic performance and versatile applications can be obtained. Understanding polymer crystallization with the presence of flow, or namely flow-induced crystallization (FIC), is crucial to optimize polymer processing parameters and to understand phase transition under far-from equilibrium conditions, as FIC is essentially a typical nonequilibrium process. Current review aims to summarizes recent achievements of FIC during last five years from three aspects: theory, experiment and simulation. First, we present the FIC model and theory, including the classical conformational entropy reduction model, the newly developed POLYdisperse STRain Accelerated Nucleation Dynamics (PolySTRAND) Model and uFIC Model. Then we discuss the FIC experiments under both well-controlled flow and complex processing conditions. Finally, we show the recent advance of FIC in computer simulation. With the fast development in modeling efficiency, more detailed nucleation and structure transition processes during FIC can be obtained, which promote the study of molecular mechanisms of FIC.

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Section: Methodsmentioning

confidence: 99%

Recent progress in flow‐induced polymer crystallization

Nie

Fan

Cao

et al. 2022

Journal of Polymer Science

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“…These results came in accordance with those obtained by Amirdine et al as the authors claimed a 3-fold increase in the kinetics of the extensional flow-induced crystallization compared to that induced under shear. 31 Furthermore, to emulate the shear flow experienced by PP during extrusion, a study performed by Romero-Diez et al showed in situ observations of the isothermal crystallization behavior under varying shear rates and CO 2 pressures. 11 It was found that at a given CO 2 pressure, the crystal nucleation density and growth rate increased (up to ∼0.6 × 10 6 crystals/cm 2 and ∼0.4 μm/min, respectively) with increasing shear rate (from 0 to 50 s −1 ).…”

Section: Introductionmentioning

confidence: 99%

“…Mechanical deformation applied to the melt is another common factor in the industrial foaming processes. Thus, studies have been abundantly conducted under shear ,− and extensional − flows to provide insight into their effects on crystallization behavior. Tabatabaei et al used in situ visualization capabilities to successfully verify the formation of PP crystallites under continuous extrusion .…”

Section: Introductionmentioning

confidence: 99%

“…These results came in accordance with those obtained by Amirdine et al. as the authors claimed a 3-fold increase in the kinetics of the extensional flow-induced crystallization compared to that induced under shear . Furthermore, to emulate the shear flow experienced by PP during extrusion, a study performed by Romero-Diez et al showed in situ observations of the isothermal crystallization behavior under varying shear rates and CO 2 pressures .…”

Section: Introductionmentioning

confidence: 99%

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In Situ Visualization of Extensional Flow-Induced Crystallization in Polypropylene under High-Pressure CO₂

Embabi,

Shen,

Tuccitto

et al. 2024

ACS Appl. Polym. Mater.

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The crystallization behavior of semicrystalline polymers under foaming-relevant conditions is among the most critical factors dictating the morphology and properties of any foam product. While cell nucleation and growth are often discussed in the plastics foaming literature, extensional flow-induced crystallization experienced postdie exit during foam stabilization is overlooked. To address this gap, we aim to build a comprehensive understanding of the nonisothermal crystallization behavior under the effects of CO 2 pressure, uniaxial extensional flow, and longchain branching. Two grades of polypropylene (PP) were used: one linear and one long-chain branched. Under quiescent conditions, an increase in CO 2 pressure led to a decrease in onset crystallization temperatures, a decrease in crystal growth rates, and an increase in nucleation densities in both resins. Additionally, X-ray diffraction analyses showed the promotion of γ-crystals under higher CO 2 pressures. Upon the introduction of uniaxial extensional flow, both resins nucleated elongated crystals (i.e., cylindrites) due to chain alignment and stretching. These cylindrites were observed via atomic force microscopy and shown to exhibit the classical shish−kebab structure. Interestingly, the long-chain-branched PP (LCB PP) nucleated more cylindrites with higher aspect ratios and exhibited a crystallization rate faster than that of its linear counterpart. Rheological characterization showed that this difference emerged from the longer relaxation behavior of the LCB PP chains. These findings may present value in modeling polymer processes while emphasizing the role of extensional flow-induced crystallization during cell growth and stabilization.

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“…Due to the commercial importance of semi-crystalline polymers, over the decades studies have been dedicated to understanding their kinetics and the influence on other properties and much progress has been made since the works of the pioneers Boon et al [15,16] and Agar et al [17] . Processing conditions like pressure [18,19] , cooling rate [20,21] , and flow conditions [22,23] may cause impacts on the crystallinity of the polymeric material and can cause changes in the kinetics, final microstructure or crystallinity content. The application of fluxes during or after the crystallization of the melt polymer can result in molecular orientation, that is, alignment of chains which in turn brings significant changes in the crystallization process [24] .…”

Section: Introductionmentioning

confidence: 99%

Impact of controlled extensional flow during extrusion of PP, PVDF and LDPE

2022

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The structure and properties of semi-crystalline polymers can be drastically tailored by extensional flows. In this work, polypropylene (PP), Polyvinylidene fluoride (PVDF) and Low Density Polyethylene (LDPE) were melt extruded through a sequence of rings designed to apply controlled extensional flows in the polymer melts. The effects of extensional flow on the structure and properties of the extruded filaments were then evaluated by mechanical tensile tests, dynamicmechanical analysis (DMA) and Differential Scanning Calorimetry (DSC). The DMA and tensile tests revealed a significant increase in terms of static and dynamic moduli for the polymers extruded through the extensional flow device. PP, PVDF and LDPE had their dynamic moduli enhanced 19%, 40% and 77%, respectively. These results were ascribed to the enhancement in crystallinity and orientation degree of the polymer chains induced by the extensional flow. The crystallinity was increased around 9% for PP, PVDF and LDPE extruded under extensional conditions.

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A novel approach to the study of extensional flow-induced crystallization

Cited by 4 publications

References 42 publications

Recent progress in flow‐induced polymer crystallization

Recent progress in flow‐induced polymer crystallization

In Situ Visualization of Extensional Flow-Induced Crystallization in Polypropylene under High-Pressure CO₂

Impact of controlled extensional flow during extrusion of PP, PVDF and LDPE

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A novel approach to the study of extensional flow-induced crystallization

Cited by 4 publications

References 42 publications

Recent progress in flow‐induced polymer crystallization

Recent progress in flow‐induced polymer crystallization

In Situ Visualization of Extensional Flow-Induced Crystallization in Polypropylene under High-Pressure CO2

Impact of controlled extensional flow during extrusion of PP, PVDF and LDPE

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Product

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About

In Situ Visualization of Extensional Flow-Induced Crystallization in Polypropylene under High-Pressure CO₂