An optical system for measuring the residence time distribution in co-rotating twin-screw extruders

Gerstorfer, Gregor; Lepschi, Alexander; Miethlinger, Jürgen; Zagar, Bernhard G.

doi:10.1515/polyeng-2013-0051

Cited by 10 publications

(5 citation statements)

References 6 publications

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“…Conversely, the process condition with higher

∆ P

achieved by higher throughput conditions has the potential to avoid the degradation reactions of COP. Gerstorfer et al [ 32 ] proposed the relationship between SME and mean residence time

t_{mean}

as follows:

t_{mean} goodbreak= \frac{SME ∙ ρ}{τ {\dot{γ}}_{mean}}

where

ρ

is the density,

{\dot{γ}}_{mean}

is the average shear rate calculated from the channel depth of the conveying screw profiles, and

τ

is the shear stress. The residence time was not measured in this study.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

A modified blister mixing element for generating extensional flow in a twin‐screw extruder: Process characterization and dispersion state of carbon nanotubes in cyclo‐olefin polymer

Matsumoto

Tanaka

2022

Polymer Engineering & Sci

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This study aimed to improve the dispersion state of single-walled carbon nanotubes (SWCNTs) in a cyclo-olefin polymer (COP) matrix by introducing extensional flow during the compounding through a twin-screw extruder (TSE). A modified mixing element with multiple holes, called a fixed blister disc (XBD), was developed. To describe the mixing performance of XBD, the flow state was characterized via numerical simulation and acquisition of process data such as pressure drop (ΔP) at XBD and specific mechanical energy (SME), while the operational conditions of TSE were varied. The dispersion state of SWCNTs was evaluated from the viewpoint of the melt viscoelastic property, surface resistivity of extruded samples and mechanical properties of injection molded samples. Furthermore, the dispersion morphology was observed via optical microscopy and scanning electron microscopy. As a result, the mixing performance of XBD was improved by increasing the ratio of throughputs Q to screw speed N s (Q/N s ) since ΔP, which is related to extensional stress, was increased. However, the trade-off relationship between ΔP and SME was confirmed versus Q/N s . Although the dispersion state at the submicron level was markedly improved with higher SME inputs, higher ΔP reduced the largest agglomerate size and improved dispersion uniformity. Consequently, the mechanical properties were improved significantly.

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“…Conversely, the process condition with higher

∆ P

achieved by higher throughput conditions has the potential to avoid the degradation reactions of COP. Gerstorfer et al [ 32 ] proposed the relationship between SME and mean residence time

t_{mean}

as follows:

t_{mean} goodbreak= \frac{SME ∙ ρ}{τ {\dot{γ}}_{mean}}

where

ρ

is the density,

{\dot{γ}}_{mean}

is the average shear rate calculated from the channel depth of the conveying screw profiles, and

τ

is the shear stress. The residence time was not measured in this study.…”

Section: Resultsmentioning

confidence: 99%

“…Conversely, the process condition with higher ΔP achieved by higher throughput conditions has the potential to avoid the degradation reactions of COP. Gerstorfer et al [32] proposed the relationship between SME and mean residence time t mean as follows:…”

Section: Effect Of Operation Conditions On Process Properties Of Xbdmentioning

confidence: 99%

A modified blister mixing element for generating extensional flow in a twin‐screw extruder: Process characterization and dispersion state of carbon nanotubes in cyclo‐olefin polymer

Matsumoto

Tanaka

2022

Polymer Engineering & Sci

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“…To investigate the residence-time distribution in the extruder for a given setting, fluorescence spectroscopy was used [ 25 ]. An amount of 0.2 g of lunar yellow (fluorescent dye) was placed in the extruder entrance and determined its residence time.…”

Section: Methodsmentioning

confidence: 99%

Properties of Starve-Fed Extrusion on a Material Containing a VHMWPE Fraction

et al. 2021

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Single-screw extruders are usually operated with the screw fully filled (flood-fed mode) and not partially filled (starve-fed mode). These modes result in completely different processing characteristics, and although starve-fed mode has been shown to have significant advantages, such as improved mixing and melting performance, it is rarely used, and experimental studies are scarce. Here, we present extensive experimental research into starve-fed extrusion at feeding rates as low as 25%. We compared various operating parameters (e.g., residence time, pressure build-up, and melting performance) at various feeding rates and screw speeds. The results show a first insight into the performance of starve-fed extruders compared to flood-fed extruders. We explored starve-fed extrusion of a polyethylene material which contains a Very High Molecular Weight Polyethylene fraction (VHMWPE). VHMWPE offers several advantages in terms of mechanical properties, but its high viscosity renders common continuous melt processes, such as compression molding, ram extrusion and sintering, ineffective. This work shows that operating single-screw extruders in extreme starve-fed mode significantly increases residence time, melt temperature, and improves melting and that-in combination—this results in significant elongation of VHMWPE particles.

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“…The reflected spectrum was evaluated in MATLAB. The extruder screw-in can be fixed in a ½" -20 UNF hole, or to the end to measure at the polymer strand [7,8].…”

Section: Fluorescence Spectroscopymentioning

confidence: 99%

Fiber length shortening and fluorescence spectroscopy as characterization method for distributive and dispersive mixing in a co-rotating twin screw extruder

Lepschi¹,

Burzic²,

Sobczak³

et al. 2016

AIP Conference Proceedings

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An optical system for measuring the residence time distribution in co-rotating twin-screw extruders

Cited by 10 publications

References 6 publications

A modified blister mixing element for generating extensional flow in a twin‐screw extruder: Process characterization and dispersion state of carbon nanotubes in cyclo‐olefin polymer

A modified blister mixing element for generating extensional flow in a twin‐screw extruder: Process characterization and dispersion state of carbon nanotubes in cyclo‐olefin polymer

Properties of Starve-Fed Extrusion on a Material Containing a VHMWPE Fraction

Fiber length shortening and fluorescence spectroscopy as characterization method for distributive and dispersive mixing in a co-rotating twin screw extruder

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