In‐process rheological monitoring of extrusion‐based polymer processes

Hilliou, L.; Covas, J. A.

doi:10.1002/pi.6093

Cited by 13 publications

(6 citation statements)

References 75 publications

(144 reference statements)

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“…This approach can be extended to the extrusion process during MatEx to develop novel nozzle designs that would allow for in situ monitoring and hence provide valuable information regarding the origin of flow instabilities at different processing conditions. Details regarding real-time in situ measurements to monitor rheological properties and structural changes during extrusion of thermoplastics have been reviewed elsewhere . It is expected that establishing relationships between polymer rheology and morphological features will aid in tailored material development for MatEx.…”

Section: Importance Of Polymer Rheology In Materials Extrusion Based Ammentioning

confidence: 99%

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Importance of Polymer Rheology on Material Extrusion Additive Manufacturing: Correlating Process Physics to Print Properties

Das

Gilmer

Biria

et al. 2021

ACS Appl. Polym. Mater.

162

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Recent advances in the field of additive manufacturing (AM) or 3D printing, have garnered serious interest for its potential to substitute time-consuming and costly subtractive and formative manufacturing techniques. Material extrusion (MatEx), employing filament and pelletbased feedstocks, is an AM technique for fabricating three-dimensional objects dictated by a computer-aided design (CAD) file in a layer-by-layer manner. Being inherently a "melt-and-form" technique, the physics of MatEx is strongly dependent on the melt flow behavior of the polymers and hence on their rheology. The focus of this review article is to analyze the current progress in rheological characterizations of filament and pellet-based polymeric feedstocks for application in MatEx. The importance of shear and temperature-dependent viscosities in relation to consistent extrusion through the print nozzle and in the standoff region between nozzle and bed will be highlighted. The importance of shear and/or extensional viscosities and extent of die swell (upon exit from the nozzle) experienced by the polymers under processing parameters relevant to MatEx will be investigated. Postextrusion from the nozzle, the rheological characteristics of the viscous polymer melt as it cools once deposited on the print bed governs the degree of interlayer welding, that impacts the mechanical performance of the printed parts. Controlling and monitoring rheological properties such as zero-shear viscosities and shear moduli of the melt is of significant importance in this region in order to ensure proper mechanical robustness and shape integrity of the deposited layers. Both experimental and theoretical approaches based on polymer chain reptation mechanisms will be reviewed in detail and suggestions to address the existing limitations associated with the process will be provided. Fundamental understanding of the correlation between the classical theories and current understanding based on recent experimentation and analysis is expected to assist the design and development of the next generation of polymer feedstocks and machine designs for MatEx-based AM.

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Section: Importance Of Polymer Rheology In Materials Extrusion Based Ammentioning

confidence: 99%

“…Details regarding real-time in situ measurements to monitor rheological properties and structural changes during extrusion of thermoplastics have been reviewed elsewhere. 125 It is expected that establishing relationships between polymer rheology and morphological features will aid in tailored material development for MatEx.…”

Section: J T T T T ( )mentioning

confidence: 99%

Importance of Polymer Rheology on Material Extrusion Additive Manufacturing: Correlating Process Physics to Print Properties

Das

Gilmer

Biria

et al. 2021

ACS Appl. Polym. Mater.

162

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“…Since melt mixing is one of the most exploited technologies for the formulation of bionanocomposites, especially at industrial level, the knowledge of the material’s rheological behavior under different flow regimes is mandatory for designing and modelling its processing and for optimizing the processing conditions [ 30 ]. In addition, the evaluation of the rheological response of nanostructured materials allows for inferring fundamental information about the state of distribution of nanofillers and the possible occurrence of polymer–filler and filler–filler interactions, being very sensitive to the modifications of the relaxation dynamics of macromolecular chains resulting from the incorporation of the nanofiller [ 31 , 32 ].…”

Section: Introductionmentioning

confidence: 99%

Structure–Property Relationships in Bionanocomposites for Pipe Extrusion Applications

et al. 2021

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In this work, bionanocomposites based on different biodegradable polymers and two types of nanofillers, namely a nanosized calcium carbonate and an organomodified nanoclay, were produced through melt extrusion, with the aim to evaluate the possible applications of these materials as a potential alternative to traditional fossil fuel-derived polyolefins, for the production of irrigation pipes. The rheological behavior of the formulated systems was thoroughly evaluated by exploiting different flow regimes, and the obtained results indicated a remarkable effect of the introduced nanofillers on the low-frequency rheological response, especially in nanoclay-based bionanocomposites. Conversely, the shear viscosity at a high shear rate was almost unaffected by the presence of both types of nanofillers, as well as the rheological response under nonisothermal elongational flow. In addition, the analysis of the mechanical properties of the formulated materials indicated that the embedded nanofillers increased the elastic modulus when compared to the unfilled counterparts, notwithstanding a slight decrease of the material ductility. Finally, the processing behavior of unfilled biopolymers and bionanocomposites was evaluated, allowing for selecting the most suitable material and thus fulfilling the processability requirements for pipe extrusion applications.

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“…Processes involving biopolymers are, however, more sensitive to structural degradation due to a highly complex and less understood dependency on heat and shear forces. Hence, the classical slit-die designs, which are widely employed in oil-based polymer applications, often produce unreliable data [14][15][16][17][18] and should be further adapted to enable well-defined food processing.…”

Section: Introductionmentioning

confidence: 99%

Principles and Guidelines for In-Line Viscometry in Cereal Extrusion

et al. 2022

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In the food industry, extrusion cooking finds numerous applications thanks to its high productivity and nutrient retention. More specifically, cereal extrusion, e.g., for savory snacks and breakfast products has an important market share. For such applications, rheology, which addresses viscous and elastic contributions, plays an important role in developing, optimizing, and controlling the extrusion manufacturing technique. In this context, conventional off-line rheometers are not ideal for providing data, as the goal is to replicate the exact thermomechanical history to which the food is subjected in the extrusion process. Hence, to achieve reliable analyses, in-line viscometers that have mostly been tested using oil-based polymers were introduced. Biopolymers (e.g., starch), however, are highly sensitive to both heat and mechanical degradation, and the viscometer design has to be adapted accordingly to produce an accurate measurement. Alongside a discussion of the different designs available, this review will address the most common methodologies for measuring the steady shear viscosity, extensional viscosity, and the first normal stress difference for food applications, providing researchers in the biopolymer and food engineering fields with a general introduction to this emerging topic.

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In‐process rheological monitoring of extrusion‐based polymer processes

Cited by 13 publications

References 75 publications

Importance of Polymer Rheology on Material Extrusion Additive Manufacturing: Correlating Process Physics to Print Properties

Importance of Polymer Rheology on Material Extrusion Additive Manufacturing: Correlating Process Physics to Print Properties

Structure–Property Relationships in Bionanocomposites for Pipe Extrusion Applications

Principles and Guidelines for In-Line Viscometry in Cereal Extrusion

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