3D Numerical Simulation of Reactive Extrusion Processes for Preparing PP/TiO2 Nanocomposites in a Corotating Twin Screw Extruder

Sun, D. P.; Zhu, X.Z.; Gao, Ming

doi:10.3390/ma12040671

Cited by 10 publications

(10 citation statements)

References 32 publications

(34 reference statements)

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“…For example, the surface of GnPs was treated with 65% nitric acid and distributed uniformly in the PP matrix, so the stiffness and toughness of the composites were boosted (Irez et al 2022 ). On the other hand, starting from the processing machinery and technology, the uniform dispersion of nanoparticles in the PP matrix can be realized by changing the shear field and tensile flow field in the mixing process (Ferras et al 2020 ; Grace 2007 ; Rwei et al 1990 , 1991 ; Sun et al 2019 ).…”

Section: Physical Recovery Technologymentioning

confidence: 99%

Disposal and resource utilization of waste masks: a review

Cui

Zhang

et al. 2023

Environ Sci Pollut Res

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Waste masks pose a serious threat to the environment, including marine plastic pollution and soil pollution risks caused by landfills since the outbreak of COVID-19. Currently, numerous effective methods regarding disposal and resource utilization of waste masks have been reported, containing physical, thermochemical, and solvent-based technologies. As for physical technologies, the mechanical properties of the mask-based materials could be enhanced and the conductivity or antibacterial activity was endowed by adding natural fibers or inorganic nanoparticles. Regarding thermochemical technologies, catalytic pyrolysis could yield considerable hydrogen, which is an eco-friendly resource, and would mitigate the energy crisis. Noticeably, the solvent-based technology, as a more convenient and efficient method, was also considered in this paper. In this way, soaking the mask directly in a specific chemical reagent changes the original structure of polypropylene and obtains multi-functional materials. The solvent-based technology is promising in the future with the researches of sustainable and universally applicable reagents. This review could provide guidance for utilizing resources of waste masks and address the issues of plastic pollution.

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Section: Physical Recovery Technologymentioning

confidence: 99%

Disposal and resource utilization of waste masks: a review

Cui

Zhang

et al. 2023

Environ Sci Pollut Res

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“…Zong et al [ 86 ] experimentally researched the rheokinetics of Poly( p ‐phenylene terephthalamide) polycondensation and then theoretically compared flow pattern, temperature, and molecular weight distribution in the conveying screw, kneading element, and SME based on 3D geometric models on the Polyflow platform. More recently, Sun et al [ 87 ] simulated the reactive preparation of PP/TiO 2 nanocomposites in a TSE with two linked screws of conveying and mixing screw elements based on the Polyflow platform as well.…”

Section: Simulation and Modellingmentioning

confidence: 99%

Experimental methods in chemical engineering: Reactive extrusion

et al. 2022

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Reactive extrusion (REX) is a manufacturing technique that combines traditional melt extrusion with chemical reactions, including polymerization, polymer functionalization, and depolymerization (chemical recycling). Single screw, counter‐rotating, and co‐rotating twin‐screw extruders (TSE) are possible configurations, but the TSE is most effective for viscous media with better mixing capability, temperature and residence time distribution control, and self‐wiping (cleaning) performance. Compared to traditional polymer processing where monomers react in tanks, followed by compounding and pelletizing, REX can operate solvent‐free in a single step. This simplifies the downstream separation and saves equipment and operational costs. However, the short residence times (on the order of seconds to minutes) of extruders limit their applications to fast reactions. For longer reactions, a sequential design and string extruders with a batch reactor extend residence times. Furthermore, the surface‐to‐volume ratio decreases with increasing scale, which introduces design complexity to remove the heat of reaction. Here, we review REX working principles, apparatuses and their elements, applications and reactions, simulation/modelling and scale‐up considerations, as well as limitations and recommendations. Web of Science indexed 579 articles that mention REX between 2017 and 2021. A bibliometric analysis of these articles identified five research clusters: composite, nano‐composite, and thermal properties; degradation, crosslinking, rheology, and acid; crystallization, polypropylene, maleic anhydride, and rheological properties; morphology, compatibilization, and copolymer; and oxidative stress and mechanisms.

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“…(2) The no-slip conditions of the fluid are assumed on the channel walls of straight section (L 0 ) and on the surfaces of the screw flight and screw shaft (r = r 1 ) [16,19,21,29,31];…”

Section: Boundary Conditionsmentioning

confidence: 99%

Numerical Simulation of Polymer Solutions in a Single-Screw Extruder

2019

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Single-screw extruders are the most common equipment used for polymer extrusion. The study of the hydrodynamics of a polymer melts flow in the extruder channel is the basis for modeling and understanding the extrusion process. In general form, the extruder includes a straight section with a screw installed in it. In this study, the three-dimensional mathematical modeling of the polymer solutions flow in the metering zone of a single-screw extruder is performed. The influences of the screw geometry (L/D 2 = 1 . . . 3) on the flow structure and the pressure drop are analyzed under a speed rotation up to 60 rpm. Aqueous solutions of 0.5% polyacrylamide (0.5% PAA) and 1.5% sodium salt of carboxymethyl cellulose (1.5% CMC) are considered as the working fluid. Appl. Sci. 2019, 9, 5423 2 of 12 the helical screw channel is unwound and considered as a flat rectangular channel [4,[17][18][19][20][21][22]. Thus, plane-parallel fluid flow in a channel of infinite width is considered instead of direct 3D modeling. Also, the principle of reversed motion is often used (tube rotation is considered at the fixed screw) [4,[17][18][19][20][21][22]. In all works, polymers are considered as shear-thinning fluid [4,[17][18][19][20][21][22].The main functional zones of the extruder are feeding (solids conveying), melting, and metering. The metering zone is the simplest for modeling in a single-screw extruder, since the flow laws of viscous fluids can be applied to the polymer melt flow [23]. In this zone, the polymer is completely molten [24]. Besides, it is the metering zone that determines the extruder performance [23].Work [4] describes a simple numerical method for solving the problem of the polymer melt flow in the metering zone of the single-screw extruder. The 2D mathematical model takes into account the presence of circulating motion, non-Newtonian behavior of the processed material, and heating of the polymer due to viscous dissipation.In [3,18,19,21,22,25], numerical solutions obtained in a 2D and 3D formulation are approximated by symbolic regression models. The heuristic approach for predicting the main characteristics of the polymer melts flow in the extruder channel is based on genetic programming. Speaking about the evolutionary computation in general, it should be noted that they, like any method using an element of randomness, do not guarantee the detection of a global extremum of the objective function (or optimal solution) for a certain time. Their main advantage is that they allow finding a "better" solution to a difficult task in less time than other methods.In contrast with the standard flat-plate model of the unwound screw channel (2D), this hydrodynamic problem is solved in a three-dimensional formulation in [17,26]. Authors of the papers consider mathematical modeling of the flow in the metering zone of a plasticizing extruder. The objective of the study was the melting of the polymer composition based on polyethylene.Work [27] presents the results of three-dimensional numerical simulation of the polymer mel...

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3D Numerical Simulation of Reactive Extrusion Processes for Preparing PP/TiO2 Nanocomposites in a Corotating Twin Screw Extruder

Cited by 10 publications

References 32 publications

Disposal and resource utilization of waste masks: a review

Disposal and resource utilization of waste masks: a review

Experimental methods in chemical engineering: Reactive extrusion

Numerical Simulation of Polymer Solutions in a Single-Screw Extruder

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