Enhanced Processing of Regrind as Recycling Material in Single-Screw Extruders

Thieleke, P.; Bonten, Christian

doi:10.3390/polym13101540

Cited by 8 publications

(7 citation statements)

References 34 publications

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“…In order to properly account for this, the compressibility of the different granules should be considered in future research as a further variable. A description of an experimental and a simulative approach to determine the compressibility can be found in [ 17 ].…”

Section: Resultsmentioning

confidence: 99%

“…Besides this proceeding the solid conveying problem in a grooved barrel can also be addressed via numerical simulation using the discrete element method (DEM) which appears to be another promising way. This DEM approach was previously examined in [ 17 , 38 ] for low screw speeds up to 100 rpm and recently thoroughly studied in [ 39 ] for screw speeds up to 500 rpm.…”

Section: Discussionmentioning

confidence: 99%

“…However, this was attributed to the fact that the circle had the largest axial length of all opening geometries with the same area. A new compression design in the feed zone was investigated in [ 17 ]. The new compression section allowed for an alignment of the specific throughput of regrind and virgin material.…”

Section: Introductionmentioning

confidence: 99%

“…The new compression section allowed for an alignment of the specific throughput of regrind and virgin material. This can be regarded as an important progress, because both throughputs commonly strongly differ in present extrusion systems since regrind materials usually exhibit significantly lower bulk densities [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of the Solid Conveying Behavior of Smooth and Grooved Single-Screw Extruders at High Screw Speeds

et al. 2022

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Single-screw extrusion at high screw speeds is established nowadays since it allows for a high mass throughput at a comparatively small extruder size. Compared to conventional extrusion at low screw speeds, a considerable non-linearity in mass throughput appears by exceeding a certain threshold screw speed. In this study, the solid conveying behavior of different plastic granules with varying geometries was investigated in a smooth, a helically and an axially grooved solid conveying zone for screw speeds up to 1350 rpm. These experimental findings are compared to classical analytical predictions in the literature. It is found for the first time that both the shape and size of the plastic granules play a decisive role in determining the threshold screw speed at which a non-linear mass throughput is observed. It is shown that small and spherical granules exhibit a later onset of non-linear throughput compared to larger lenticular and cylindrical shaped granules. Moreover, it is revealed that the mass throughput equalizes for an axially and a helically grooved solid conveying zone at high screw speeds. This is contrary to the low screw speed range where the axially grooved barrel results in a significantly higher throughput than the helically grooved barrel. Thus, the maximum throughput at high screw speeds is limited by the granule stream provided by the hopper opening and is no longer governed by the groove angle.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of the Solid Conveying Behavior of Smooth and Grooved Single-Screw Extruders at High Screw Speeds

et al. 2022

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“…Existing deviations were attributed to the lack of a backpressure in the simulations [35]. Recently, the DEM was also used for analyzing the flow behavior of regrind as a recycling material in a conical and grooved feed section [36].…”

Section: Numerical Investigation Of Solids Conveyingmentioning

confidence: 99%

Numerical Simulation of Solids Conveying in Grooved Feed Sections of Single Screw Extruders

Brüning

Schöppner

2022

Polymers

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For plastic processing extruders with grooved feed sections, the design of the feed section by means of analytical calculation models can be useful to reduce experimental costs. However, these models include assumptions and simplifications that can significantly decrease the prediction accuracy of the throughput due to complex flow behavior. In this paper, the accuracy of analytical modeling for calculating the throughput in a grooved barrel extruder is verified based on a statistical design of experiments. A special focus is placed on the assumptions made in the analytics of a backpressure-independent throughput, the assumption of a block flow and the differentiation of the solids conveying into different conveying cases. Simulative throughput tests with numerical simulation software using the discrete element method, as well as experimental throughput tests, serve as a benchmark. Overall, the analytical modeling already shows a very good calculation accuracy. Nevertheless, there are some outliers that lead to larger deviations in the throughput. The model predominantly overestimates the throughputs, whereby the origin of these deviations is often in the conveying angle calculation. Therefore, a regression-based correction factor for calculating the conveying angle is developed and implemented.

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Current technological options for recycling packaging waste: Challenges and opportunities in India

Hossain,

Ghinangju,

Biswal

et al. 2023

WIREs Energy & Environment

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Packaging in India comprises around 59% of total plastic consumption, with most of the waste originating from single‐use and short shelf‐life products. The plastic recycling industry is primarily made up of informal processing units which have predominantly been recycling Polyethylene terephthalate (PET) waste due to ease of availability, sorting, and higher upscale values than most other single‐use packaging. Other packaging, such as Polyethylene (PE) shopping bags, thin film and multi‐material packaging waste is either directed to downcycling, incineration or landfill. About 94% of total recycling in India is carried out through mechanical recycling, which comes through informal and fragmented recycling units. Most of the recycling units in India rely on rudimentary technologies. One example is a visual sorting system that involves manual handling to recycle plastic waste, which is resource and time intensive. There has been some advancement towards chemical and energy recovery techniques, but mostly been limited to pilot‐scale deployment. This article explores the existing and emerging technological options suitable for recycling post‐consumer flexible plastic packaging waste in India. It also discusses the status of multi‐material packaging waste, and the advancement being made for its recycling. The paper also explores India's increased momentum in the use of innovative recycling techniques, such as distributed recycling and manufacturing techniques and plastic waste in steel manufacturing.This article is categorized under: Climate and Environment > Ecosystem Services Climate and Environment > Circular Economy Emerging Technologies > Materials

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Enhanced Processing of Regrind as Recycling Material in Single-Screw Extruders

Cited by 8 publications

References 34 publications

Experimental Investigation of the Solid Conveying Behavior of Smooth and Grooved Single-Screw Extruders at High Screw Speeds

Experimental Investigation of the Solid Conveying Behavior of Smooth and Grooved Single-Screw Extruders at High Screw Speeds

Numerical Simulation of Solids Conveying in Grooved Feed Sections of Single Screw Extruders

Current technological options for recycling packaging waste: Challenges and opportunities in India

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