Practicing the concept of “structuring” processing in the manufacture of polymer films

Wu, Tong; Wang, Ke; Chen, Xiufeng; Yang, Xuemei; Xiang, Ming; Fu, Qiang

doi:10.1007/s11426-022-1520-9

Cited by 7 publications

(2 citation statements)

References 137 publications

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“…Here, we focus on the "structuring" polymer processing based on injection molding. Other "structuring" polymer processing methods have been reviewed by Peterlin 123 and An et al 124 on extrusion, Fu et al 125 and Dziadowiec et al 126 on film casting, and Xu et al 127 and Hufenus et al 128 on melt spinning. Based on conventional injection molding (CIM), a novel type of injection molding has been developed, which introduces a distinct melt flow feature during injection molding usually in the packing stage; i.e., the melt flow in the cavity of mold is manipulated by using pressure-driven flow.…”

Section: "Structuring" Polymer Processing Based On Ficpmentioning

confidence: 99%

Flow-Induced Polymer Crystallization under Pressure and Its Engineering Application in “Structuring” Polymer Processing

Zhong,

Yang,

Lei

et al. 2024

Macromolecules

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Polymer processing is an essential step in achieving the desired shape and properties of polymer parts that are being broadly used in areas from packaging to aerospace. However, the design of the processing for new products is a matter of trial and error in practice. This is partly due to a limited understanding of polymer crystallization under realistic processing conditions, where strong shear flow and elevated pressure are coupled in an inhomogeneous manner. Unlike the well-established research topics that focus on polymer crystallization under the sole effect of pressure or shear flow, the subject of this Perspective is crystallization under processing conditions which include both, i.e., flow-induced crystallization under pressure (FICP). Here we focus particularly on recent advances in this field. Starting with a brief introduction of the special experimental devices for studying FICP, we discuss the remarkable interplay between flow and pressure and its effect on crystallization kinetics, crystal structure, and morphology. Accelerated crystallization, multiphase diagrams, and newfound crystalline morphologies may enrich the theory of polymer crystallization and require its further development. We then summarize the in situ studies of polymer crystallization under realistic processing conditions based on state-of-the-art characterization systems. This is followed by an overview of "structuring" polymer processing methods based on the theoretical understanding of FICP. The paper concludes with an assessment of the prospective future research directions.

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Section: "Structuring" Polymer Processing Based On Ficpmentioning

confidence: 99%

Flow-Induced Polymer Crystallization under Pressure and Its Engineering Application in “Structuring” Polymer Processing

Zhong,

Yang,

Lei

et al. 2024

Macromolecules

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“…iPP is a frequently used polymer in industrial processing, and scientific research is used as a model material in that work. [ 126–128 ] The iPP samples with well‐defined microstructure are obtained by annealing or adding a nucleating agent. In‐situ synchrotron X‐ray scattering, among other measurements, is employed in characterizing structural evolution under uniaxial stretching, creep, and stress relaxation tests.…”

Section: The Evolution Of Microstructure and Characterization Of A Si...mentioning

confidence: 99%

Evolution of the Deformation‐ and Flow‐Induced Crystallization and Characterization of the Microstructure of a Single Spherulite, Lamella, and Chain of Isotactic Polypropylene

Sharaf,

Kloczkowski

2023

Macro Chemistry & Physics

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Isotactic polypropylene (iPP) is a frequently used polymer in industrial processing and scientific research, used as a model material. This review highlights some current and forefront issues in polymer science and engineering. This review alludes to classical deformation schemes to interpret the complicated deformation in isotactic polypropylene as a semicrystalline polymer. Also, due to the complex hierarchical structures of crystallized polymers, we are concerned mainly with the progress on the multi‐scale and multi‐stage microstructural evolution covering each deformation stage from the initiation of plasticity until failure, particularly in terms of crystalline morphology changes. Specifically, the characterization of the microstructure evolution of a single spherulite, lamella, and chain of isotactic polypropylene will be emphasized and mentioned. Here, we are most interested in the results obtained from stretching (strain‐induced) orientation and crystallization studies accompanied by the in situ scattering and spectroscopy techniques offering a detection window from nano to micrometer scale, which should be able to reflect the microstructural changes at different length scales of interest.During polymer processing, the melts are frequently subjected to shear or/and elongation flow fields, producing flow‐induced molecular chain orientation in the melt. The oriented molecular chains crystallize differently than those encountered under quiescent conditions. Thus, orientation‐induced crystallization has long been an object of intense interest. A vast body of research was reported about the effects of preorientation on the crystallization of various polymers. Among them, iPP is most frequently studied since its diversified structure and morphology are very sensitive to changes in processing conditions and molecular parameters.This article is protected by copyright. All rights reserved

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Structural Characteristics of Fibrillar Crystals in Uniaxially Stretched Isotactic Polypropylene Dominated by Temperature and Strain

Lin,

Guo,

Huang

et al. 2024

Macro Materials & Eng

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The spherulitic morphology of isotactic polypropylene can be transformed into the oriented fibrillar morphology through hot stretching processes with varying temperature (Ts) or altering strain (εt). The effects of Ts and εt on the structural characteristics of fibrillar crystals are comprehensively investigated with respect to crystal orientation, long periodic spacing, lamellar thickness (Lc), crystallinity (Xc), melting point, and chain relaxation behavior. Small‐angle X‐ray scattering patterns illustrate that the fibrillar crystals consist of alternated stacks of crystalline lamellae and amorphous layers. High Ts leads to a low orientation degree of lamellae, whereas large εt facilitates a high orientation level. The Xc and mean Lc are improved continuously with the increasing of Ts or εt, indicating a stretching‐enhanced crystallization behavior driven by the two factors. The endothermic profiles reveal that new chain‐folded lamellae with relatively thinner thickness form during the hot stretching process. The formation of thinner lamellae is dominated by the melting–recrystallization mechanism. This work would provide guidance for optimizing process conditions to manipulate the microstructure of hot‐stretched semicrystalline polymers.

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Practicing the concept of “structuring” processing in the manufacture of polymer films

Cited by 7 publications

References 137 publications

Flow-Induced Polymer Crystallization under Pressure and Its Engineering Application in “Structuring” Polymer Processing

Flow-Induced Polymer Crystallization under Pressure and Its Engineering Application in “Structuring” Polymer Processing

Evolution of the Deformation‐ and Flow‐Induced Crystallization and Characterization of the Microstructure of a Single Spherulite, Lamella, and Chain of Isotactic Polypropylene

Structural Characteristics of Fibrillar Crystals in Uniaxially Stretched Isotactic Polypropylene Dominated by Temperature and Strain

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