Effect of Mixing Intensity on Foaming Behavior of LLDPE/HDPE Blends in Thermal Induced Batch Process

Shahi, Peyman; Behravesh, Amir Hossein; Haghtalab, Ali; Rizvi, Ghaus; Pop‐Iliev, Remon; Goharpei, Fatemeh

doi:10.1080/03602559.2015.1132444

Cited by 15 publications

(21 citation statements)

References 81 publications

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“…LLDPE and HDPE show highest and lowest values, while intermediate values were observed for the blends. The observed differences can be explain by variation in crystallinity of the materials, as measured by DSC tests and reported in our prior study [49]. Same trend as gas uptake was obtained for crystallinity, highest value for LLDPE, lowest value for HDPE and intermediate values for the blends.…”

Section: Gas Uptakesupporting

confidence: 78%

“…Figure 4 also demonstrates more uniform cell structure for Blend B1 and Blend B2 which have been mixed at the speeds of 10 and 60 rpm. This can be explained by balanced rheological properties of these blends, which was described in our previous study [49]. Rheology results (Figure 1) along with void fraction and foam morphology results suggest that melt elasticity and viscosity of the material is required to be in a balanced range to obtain good foam morphology.…”

Section: D Micro-ct Imagessupporting

confidence: 70%

“…In this study, Micro-CT X-ray scanner and 3D image analysis were effectively exploited to assess in detail, the cellular morphology of foamed structures produced with PE blends and neat materials. In our previous study [49], thermal and rheological properties of PE blends produced at different mixing intensities were studied to find correlations with foam-ability.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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Non-invasive x-ray micro-computed tomography was employed for thorough quantitative and qualitative analysis of the cellular structure of foams made of linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and their blends. Special emphasis was given to the differences between the results of 3D and 2D analyses, to evaluate the possible errors while studying the morphology using conventional 2D techniques (e.g. SEM). Blends with the weight compositions of 90%LLDPE/10%HDPE and 75%LLDPE/25%HDPE were produced at different rotor speeds of 10, 60 and 120 rpm and batch foaming was examined over a wide range of temperature. The void fraction values from 2D and 3D analysis were found to agree well with those obtained with the Archimedes method. Results showed more uniform cell size distribution for blends mixed at the lower spectrum of screw rotational speed. Among the blends with higher void fraction values and relatively uniform cellular structure, higher average cell size (3–30%) and cell population density (1.25–2.5 times) were noticed in 3D analysis compared with 2D data. The micro-CT images at different cross sections revealed anisotropic cell growth and more elongated cells along the thickness of the specimen. It was also observed that, with increase in foaming temperature, cell shrink prevailed over cell coalescence in the samples with lower viscosity (prepared at low rpm of 10), while for those with higher viscosity (prepared at an rpm of 60) cell coalescence was more dominant.

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Section: Gas Uptakesupporting

confidence: 78%

Section: D Micro-ct Imagessupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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“…At high frequencies (above 100 rad/s), the viscosities of HDPE, LLDPE, and LLDPE/HDPE blends tend to approach each other. A possible explanation is that the polymer chains begin to untangle and slide over each other, thus allowing the orientation of the polymer chains in the direction of the flow 21,22 …”

Section: Resultsmentioning

confidence: 99%

“…A possible explanation is that the polymer chains begin to untangle and slide over each other, thus allowing the orientation of the polymer chains in the direction of the flow. 21,22 Figure 3 shows the plots of storage modulus (G') as a function of ω of LLDPE, HDPE, and LLDPE/HDPE blends containing 10-50 wt% of HDPE. HDPE, LLDPE, and HDPE/LLDPE blends present a liquid-like behavior (G'α ω 2 ) at low frequencies (terminal zone).…”

Section: Rheological Measurements Under Dynamic-oscillatory Shear Flowmentioning

confidence: 99%

Linear low‐density polyethylene/high‐density polyethylene blends: Effect of high‐density polyethylene content on die swell and flow instability

Freitas

Oliveira

Alves

et al. 2020

J of Applied Polymer Sci

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This work aimed to evaluate the effect of high-density polyethylene (HDPE) content and of shear rate on the die swell and flow instability of linear lowdensity polyethylene (LLDPE)/HDPE blends. The results showed that the die swell of the LLDPE/HDPE blends increased with the increase in the shear rate. At high shear rates, the increase in the HDPE content led to an increase in the die swell of LLDPE/HDPE blends. The surface morphology analysis of the extrudates by optical and scanning electron microscopy revealed the presence of sharkskin and stick-slip flow instabilities in LLDPE and LLDPE/HDPE blends at the shear rates investigated. These instabilities were attenuated with the addition of HDPE and almost disappeared in the LLDPE/HDPE blend containing 50 wt% of HDPE.

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Effects of mechanical recycling on optical properties and microstructure of recycled high‐density polyethylene pellets and bottles

Zeng

Guo

et al. 2022

J of Applied Polymer Sci

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The demand for recycling high-density polyethylene (HDPE) utilizing mechanical recycling technologies is currently felt strongly by both society and industry. However, thermal oxidation of the polymer during the recycling process may lead to irreversible changes in the material properties of recycled high-density polyethylene (rHDPE). The effects of mechanical recycling on the optical characteristics and microstructure of rHDPE pellets and bottles were investigated in this study. The results revealed that the apparent color of the rHDPE became more yellow and gray compared to the virgin HDPE (vHDPE), and showed a signal at 670-680 nm in the solar reflectance spectrum. The thermal oxidation of rHDPE considerably raised the absorption intensities of carbonyl, ester, and hydroxyl groups in attenuated total reflection Fourier transform infrared spectrum. In addition, the presence of carbonyl and hydroxyl unsaturated chemicals might make it challenging to recognize the distinctive peaks of vHDPE in the ultraviolet-visible diffuse reflectance (UV-Vis-DIR) spectra at wavelengths less than 400 nm. Thermal oxidation of rHDPE was also confirmed in the C OH, C O, and O C O valence structures of C1s and O1s. A characteristic valence band (VB) profile at 25 eV can be used as the recognizable information for the oxidation of rHDPE. The microstructure of the surface of rHDPE pellets exhibited rough and uneven morphological defects. The higher recycled content made rHDPE bottles' surface morphology rougher and their cross-section microstructure thinner and more porous than vHDPE bottles.

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Effect of Mixing Intensity on Foaming Behavior of LLDPE/HDPE Blends in Thermal Induced Batch Process

Cited by 15 publications

References 81 publications

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

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

Linear low‐density polyethylene/high‐density polyethylene blends: Effect of high‐density polyethylene content on die swell and flow instability

Effects of mechanical recycling on optical properties and microstructure of recycled high‐density polyethylene pellets and bottles

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