Morphological Analysis of Foamed HDPE/LLDPE Blends by X-ray Micro-Tomography: Effect of Blending, Mixing Intensity and Foaming Temperature

Shahi, Peyman; Behravesh, Amir Hossein; Rasel, Sheikh; Rizvi, Ghaus; Pop‐Iliev, Remon

doi:10.1177/026248931703600501

Cited by 8 publications

(8 citation statements)

References 67 publications

(72 reference statements)

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“…Also, a material with the QAS (but without sepiolites) was produced to analyse its effect on the foaming behaviour. Rheology measurements, MFI and DSC were used to validate that the extrusion process did not affect significantly the morphology and properties of PMMA (see supporting information for these results).…”

Section: Methodsmentioning

confidence: 99%

Anisotropy in nanocellular polymers promoted by the addition of needle‐like sepiolites

Bernardo

León

Rodríguez‐Pérez

2019

Polymer International

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This work presents a new strategy for obtaining nanocellular materials with high anisotropy ratios by means of the addition of needle-like nanoparticles. Nanocellular polymers are of great interest due to their outstanding properties, whereas anisotropic structures allow the realization of improved thermal and mechanical properties in certain directions. Nanocomposites based on poly(methyl methacrylate) (PMMA) with nanometric sepiolites are generated by extrusion. From the extruded filaments, cellular materials are produced using a two-step gas dissolution foaming method. The effect of adding various types and contents of sepiolites is investigated. As a result of the extrusion process, the needle-like sepiolites are aligned in the machine direction in the solid nanocomposites. Regarding the cellular materials, the addition of sepiolites allows one to obtain anisotropic nanocellular polymers with cell sizes of 150 to 420 nm and cell nucleation densities of 10 13 -10 14 nuclei cm −3 and presenting anisotropy ratios ranging from 1.38 to 2.15, the extrusion direction being the direction of the anisotropy. To explain the appearance of anisotropy, a mechanism based on cell coalescence is proposed and discussed. In addition, it is shown that it is possible to control the anisotropy ratio of the PMMA/sepiolite nanocellular polymers by changing the amount of well-dispersed sepiolites in the solid nanocomposites.

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Section: Methodsmentioning

confidence: 99%

Anisotropy in nanocellular polymers promoted by the addition of needle‐like sepiolites

Bernardo

León

Rodríguez‐Pérez

2019

Polymer International

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“…There are three kinds of foaming processes: extrusion, [14,15] injection molding, [16][17][18] and batch processing. [19][20][21] The batch foaming is extensively utilized in research, since it allows a fine control of processing parameters in a vessel. However, this discontinuous process leads to a low productivity, which limits its usage in industrial application.…”

Section: Introductionmentioning

confidence: 99%

Acoustic Absorption Properties of Polystyrene‐Pyrolytic Pinus Resinosa Composite Foams Prepared by Torsion‐Induced Extrusion

Jian

Shahi

Semeniuk

et al. 2021

Macro Materials & Eng

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A lightweight acoustic composite foams with unique sound absorption feature is reported, that is, the foam acoustic composite demonstrates surprisingly stable sound absorption performance in a wide bandwidth of frequency. The unique acoustic properties are attributed to the highly exfoliated nanolayered biocarbon nucleation, derived from the pyrolytic pinus resinosa, with tailoring the foam structure and properties. Polystyrene (PS) composite foams with porous graphitic biocarbon are obtained by sequestering recycled supercritical carbon dioxide assisted with torsion extrusion technology. Unique design concept is validated and implemented in the torsion-induced extrusion process, with good mixing and thermal management, offering a suitable environment for the nucleation, uniform growth, and stability of the cells on the foam structures. The presence of porous graphitic nanolayered characteristics of biocarbon in the composition changes the sound insulation behavior from resonant absorber of pure PS closed cell foam to stable acoustic performance over a wide range in high frequency band (3.5-6.4 kHz), while preserving the closed cell structure. This allows the tailoring of cell structures and properties with varying renewable carbon content, so as to better adapt to a broadband sound absorption applications including absorbing panels, anechoic chamber with high accuracy and aircraft acoustic stealth technology.

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“…X-ray computed tomography (Micro-CT) is a non-destructive 3 D imaging technique in providing more realistic results for polymeric foams internal structure. This technique, which was initially introduced for medical diagnosis purposes, is nowadays being used in many different scientific fields for the sake of analyzing the internal structure of various materials including composites, 13–17 cellular products, 11,18–20 food products, 21–23 metal foams, 24–28 biological tissues/bones, 29–33 rocks, 34–37 and ceramic foams. 24,38,39 The technique is based upon the principle that object with different densities can attenuate X-ray intensity to different degrees.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the accuracy and efficiency of characterizing polymeric cellular structures using 3D-based computed tomography

Karimipour-Fard

Naeem

Mohany

et al. 2020

Journal of Cellular Plastics

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Characterizing the morphology of polymeric foams is crucial for determining their practical applicability. The internal cellular structure of polymeric foams is typically analyzed by 2 D imaging techniques, such as Scanning Electron Microscopy (SEM) and optical microscopy. The problem with these techniques is that their tests are tedious, destructive, and the accuracy of the obtained results is questionable. The objective of this paper is to establish and experimentally verify an efficient 3- dimensional (3 D) Microcomputed-tomography based methodology for reliably estimating and characterizing each of the phases commonly present in multiple types of polymeric foam samples, such as the open, the closed, and the solid phase. A comparative study was carried out between morphology data obtained from 2-dimensional (2 D) analysis and those obtained from 3 D analysis to investigate the reliability of the 2 D analysis results. In this context, the experimental results revealed that by using a 2 D method the open porosity was underestimated at the expense of closed porosity, which in turn was overestimated, while the total porosity was not impacted. Also, visualization of the internal structure of polymer foams by using Micro-CT provides details about the 3 D space which cannot be obtained from SEM images. The analysis of foamed specimen demonstrated that the polymeric foam phases extracted from Micro-CT images were in agreement with the experimentally measured values of total porosity of the samples. In an effort to reduce computational requirements, the effects of reducing data size on the accuracy of results has also been studied by averaging image pixels in 3 D space and the results were compared for multiple types of foam structures. This method reduced the processing time considerably, and yielded comparable porosity values. However, the number of detected pores were lowered due to the inability of this method to detect very small cells after 3 D averaging of image pixels.

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Morphological Analysis of Foamed HDPE/LLDPE Blends by X-ray Micro-Tomography: Effect of Blending, Mixing Intensity and Foaming Temperature

Cited by 8 publications

References 67 publications

Anisotropy in nanocellular polymers promoted by the addition of needle‐like sepiolites

Anisotropy in nanocellular polymers promoted by the addition of needle‐like sepiolites

Acoustic Absorption Properties of Polystyrene‐Pyrolytic Pinus Resinosa Composite Foams Prepared by Torsion‐Induced Extrusion

Enhancing the accuracy and efficiency of characterizing polymeric cellular structures using 3D-based computed tomography

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