Application of Raman Spectroscopy for Determining Residence Time Distributions in Extruder Reactors

Ward, N. J.; Edwards, Howell G. M.; Johnson, A. F.; Fleming, D. J.; Coates, P. D.

doi:10.1366/0003702963905754

Cited by 21 publications

(13 citation statements)

References 2 publications

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“…This can be seen by comparing the amount of tracer (wt%) used in experiments, based on the weight fraction of tracer to the extrusion mass flow per minute. Spectroscopic techniques operation in the NIR region used 2 wt% for NIR and 3 wt% for Raman compared to 0.003 wt% for fluorescence and 0.03 wt% for the visible range monitored in this study. The costs of the system are also low compared to spectroscopic methods.…”

Section: Discussionmentioning

confidence: 99%

“…Fluctuations were mainly due to changes in the presentation of the strands to the camera and presumably due to sticking of material on surfaces or cavities during the extrusion process. This nonidealized material flow can be observed with several other measurement techniques as well (e.g., NIR [28] and Raman [16]). When material adhered to the screw tips or only very short strands were formed, the observed fluctuations were higher.…”

Section: Linearity and Repeatabilitymentioning

confidence: 94%

“…Raman spectroscopy was used in one of the first published inline measurement studies to detect a TiO 2 tracer [16]. Fluorescence spectroscopy was utilized as well, with tracers such as perylene [17,18] and anthracene [19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

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In‐line measurement of residence time distribution in melt extrusion via video analysis

Wahl

Hörl

Kaiser

et al. 2017

Polymer Engineering & Sci

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Residence time distribution (RTD) is an important factor in melt extrusion as it strongly influences the product quality. It can cause degradation of the active pharmaceutical ingredient (API), which can be reduced by shorter mean residence times, and the content uniformity, which can be improved by broadening the RTD caused by axial mixing. In our study, we developed an inline video analysis that to date has mainly been applied offline. For extrusion, hydrophilic polymer and a surfactant were used as a molten matrix, in which an API was embedded. The video analysis consisted of four steps: (1) segmentation of the image to mask the strands, (2) calculation of average color values for the segmented pixels of each frame, (3) fitting of the obtained color curve with an analytical solution, and (4) calculating several RTD measures (e.g., the minimal and mean RT) for better comparison of the results. The RTD measures were responses in the design of experiments (DoE), which included the process parameters screw design, screw speed, and throughput. This analysis clearly showed that screw design had the strongest effect on the RTD measures. The results suggest that video analysis is a suitable tool for inline RTD measurements. POLYM. ENG. SCI., 58:170–179, 2018. © 2017 Society of Plastics Engineers

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Section: Discussionmentioning

confidence: 99%

Section: Linearity and Repeatabilitymentioning

confidence: 94%

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In‐line measurement of residence time distribution in melt extrusion via video analysis

Wahl

Hörl

Kaiser

et al. 2017

Polymer Engineering & Sci

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“…As early as 1982, Hendra et al 70 used polarized Raman spectroscopy to analyze polymers inside an extruder, to give information on chain conformation, orientation and crystallinity. More recently, Ward et al 71 measured the residence time distribution of a polymer in a twin-screw extruder by doping in a "plug" of a suitable tracer into the polymer stream. However, in both of these examples a laboratory scale extruder was brought to the focus of the Raman spectrometer.…”

Section: Polymer Morphologymentioning

confidence: 99%

Process Measurements by Raman Spectroscopy

Everall

Clegg²,

King³

2001

Handbook of Vibrational Spectroscopy

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Raman spectroscopy has long been recognized as a powerful analytical tool, capable of characterizing a wide range of materials, but for many years the size and complexity of instrumentation confined it to the research laboratory, making process analysis impractical. However, compact, sensitive and robust Raman instruments are now available that can be readily interfaced to production processes. This article attempts to illustrate the general capabilities of Raman spectroscopy as a process analytical tool. We first consider the instrumental and engineering aspects of making Raman measurements under production conditions, and then discuss some of the areas in which it has been fruitfully employed. The application examples discussed were chosen to cover the main range of sample types that one might encounter in the industry. We also describe some common artifacts and problems, which can arise and confuse the new practitioner.

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“…In a twin‐screw extruder, the developed residence time for every fluid element is non‐uniform due to back mixing as well as wall adherence on the barrel wall or the screw surface. Therefore, a distribution of residence times is developed depending on different machine alignments as well as the polymer (formulation) itself …”

Section: Introductionmentioning

confidence: 99%

Measuring the residence time distribution in a twin screw extruder with the use of NIR‐spectroscopy

Laske

Witschnigg

Selvasankar

et al. 2013

J of Applied Polymer Sci

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The mean residence time (MRT) and the residence time distribution (RTD) of polypropylene in a twin-screw extruder was determined directly in-line with the help of near infrared (NIR) spectroscopy and the use of an UV-absorber as tracer. Different experiment alignments such as screw speed, mass throughput, back pressure as well as tracer content and their influence on MRT and RTD have been investigated.

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Application of Raman Spectroscopy for Determining Residence Time Distributions in Extruder Reactors

Cited by 21 publications

References 2 publications

In‐line measurement of residence time distribution in melt extrusion via video analysis

In‐line measurement of residence time distribution in melt extrusion via video analysis

Process Measurements by Raman Spectroscopy

Measuring the residence time distribution in a twin screw extruder with the use of NIR‐spectroscopy

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