On-line monitoring of the residence time distribution along a kneading block of a twin-screw extruder

Carneiro, O. S.; Covas, J. A.; Ferreira, João F.; Cerqueira, M. F.

doi:10.1016/j.polymertesting.2004.05.001

Cited by 43 publications

(32 citation statements)

References 25 publications

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“…O parâmetro E(t) representa a variação da concentração de marcador na saída da extrusora e F(t) representa a quantidade acumulada de traçador na saída após um dado intervalo de tempo [12][13][14]. Essas funções são definidas como:…”

Section: Modelo Teóricounclassified

Método Simples Para Determinar Distribuição De Tempo De Residência De Polímeros Em Extrusora a Partir De Medidas De Luminância

Silva¹,

Yoshida²,

Takimoto³

et al. 2017

Tecnol. Metal. Mater. Min.

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ResumoA distribuição de tempo de residência (RTD) é uma ferramenta poderosa que pode ser usada para a análise das condições do processo de extrusão. Quando se trata de polímeros, a qualidade do produto acabado é fortemente afetada pelos parâmetros de processamento a que estes materiais são submetidos. Desta forma, a RTD tem sido amplamente empregada para avaliar a extrusão destes materiais. Neste trabalho foi determinada a RTD do polipropileno processado em extrusora monorrosca e, além disso, foi avaliada a influência da velocidade de rotação da rosca sobre o tempo médio de residência e a capacidade de mistura da extrusora. Nas condições de processamento utilizadas, os resultados mostraram que o aumento da rotação reduz o tempo de residência e, ao mesmo tempo, favorece uma melhor homogeneização do fundido. Palavras-chave: Extrusão; Distribuição de tempo de residência; Luminância; Polímeros. SIMPLE METHOD FOR DETERMINATION OF THE RESIDENCE TIME DISTRIBUTION OF POLYMERS IN EXTRUDER FROM LUMINANCE MEASUREMENTS AbstractThe residence time distribution (RTD) is a powerful tool and it can be used to analyze the conditions of the extrusion process. For polymers, the quality of the products is strongly affected by the processing parameters that are applied to such materials. Thus RTD has been widely used to evaluate their extrusion. In this work, RTD of polypropylene extrusion in a single screw extruder was determined and the influence of the rotation speed of the screw on the mean residence time and the mixing ability of the extruder were evaluated. Under the range of the extrusion conditions, the results have shown that the increment of the rotation speed reduces the residence time and, at the same time, enhances the homogeneity of the melt.

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Section: Modelo Teóricounclassified

Método Simples Para Determinar Distribuição De Tempo De Residência De Polímeros Em Extrusora a Partir De Medidas De Luminância

Silva¹,

Yoshida²,

Takimoto³

et al. 2017

Tecnol. Metal. Mater. Min.

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“…The RTD density function, E(t), shows the variation of the tracer concentration at the exit and is given by the following equation (Carneiro et al, 2004):…”

Section: Evaluations Of the Mixing Efficiencymentioning

confidence: 99%

Evaluations of Flow and Mixing Efficiency in the Kneading Disks of a Novel Tri-Screw Extruder

Zhu¹,

Wang²,

Wang³

2016

JAFM

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The forward or backward stagger angles of the kneading disks have great effects on configures of the special center region along axial length in a novel tri-screw extruder. In this paper, the flow and mixing of a nonNewtonian polyethylene in kneading disks of a tri-screw extruder were simulated using three-dimensional finite element modeling based on mesh superposition technique. Three types of kneading disks, neutral stagger, staggered 30° forward and staggered 30° reverse were considered for the tri-screw extruder. The effects of stagger angles of kneading disks on the flow pattern in the tri-screw extruder were investigated. Moreover, at different stagger angles, the dispersive and distributive mixing efficiencies in the kneading disks of the tri-screw extruder and the twin-screw extruder were calculated and compared by means of mean shear rate, stretching rates, maximal stress magnitudes, mixing index, residence time distribution (RTD) and logarithm of area stretch. It is found that increasing the stagger angles decreases the axial velocities of polymer melt in the center region for the tri-screw extruder. The staggered 30° reverse is relatively reasonable for the tri-screw extruder and neutral stagger for the twin-screw extruder for the mixing efficiency. In comparison, the kneading disks in the tri-screw extruder have higher distributive and dispersive mixing efficiencies than those in the twin-screw extruder with the same stagger angles.

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“…Carneiro et al [73] determined the RTD along a kneading block via in-line monitoring of the light emission of a fluorescent tracer (perylene) in a slit die attached to a singlescrew extruder and at several locations along a corotating twin-screw extruder. RTD measurements are often used to monitor and control process attributes such as consistency, extent of polymer degradation and degree of mixing.…”

Section: Fluorescence Spectroscopymentioning

confidence: 99%

“…Solutions to accommodate the optical probe: (a) slit die used for measurements in a single screw extruder; (b) modified sampling device for partial measurements in a twin-screw extruder; and (c) device for partial measurement along a transparent barrel. [73] Dielectric spectroscopy Perusich and McBrearty [77] applied dielectric spectroscopy to make composition measurements of the comonomer concentration along polymer chains. Dielectric spectroscopy imposes an electric field across the flowing polymer and measures the resultant alternating current produced from the movement and energy associated with dipole orientation and ionic conduction.…”

Section: Terahertz Spectroscopymentioning

confidence: 99%

Process monitoring and visualization solutions for hot-melt extrusion: a review

Saerens

Vervaet

Remon

et al. 2014

Journal of Pharmacy and Pharmacology

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Objectives Hot-melt extrusion (HME) is applied as a continuous pharmaceutical manufacturing process for the production of a variety of dosage forms and formulations. To ensure the continuity of this process, the quality of the extrudates must be assessed continuously during manufacturing. The objective of this review is to provide an overview and evaluation of the available process analytical techniques which can be applied in hot-melt extrusion. Key Findings Pharmaceutical extruders are equipped with traditional (univariate) process monitoring tools, observing barrel and die temperatures, throughput, screw speed, torque, drive amperage, melt pressure and melt temperature. The relevance of several spectroscopic process analytical techniques for monitoring and control of pharmaceutical HME has been explored recently. Nevertheless, many other sensors visualizing HME and measuring diverse critical product and process parameters with potential use in pharmaceutical extrusion are available, and were thoroughly studied in polymer extrusion. The implementation of process analytical tools in HME serves two purposes: (1) improving process understanding by monitoring and visualizing the material behaviour and (2) monitoring and analysing critical product and process parameters for process control, allowing to maintain a desired process state and guaranteeing the quality of the end product. Summary This review is the first to provide an evaluation of the process analytical tools applied for pharmaceutical HME monitoring and control, and discusses techniques that have been used in polymer extrusion having potential for monitoring and control of pharmaceutical HME.

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On-line monitoring of the residence time distribution along a kneading block of a twin-screw extruder

Cited by 43 publications

References 25 publications

Método Simples Para Determinar Distribuição De Tempo De Residência De Polímeros Em Extrusora a Partir De Medidas De Luminância

Método Simples Para Determinar Distribuição De Tempo De Residência De Polímeros Em Extrusora a Partir De Medidas De Luminância

Evaluations of Flow and Mixing Efficiency in the Kneading Disks of a Novel Tri-Screw Extruder

Process monitoring and visualization solutions for hot-melt extrusion: a review

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