Compression Molding of Polyethylene Foams under a Temperature Gradient: Morphology and Flexural Modulus

Barzegari, Mohamad Reza; Yao, Jiaolian; Rodrigue, Denis

doi:10.1177/026248930902800401

Cited by 9 publications

(18 citation statements)

References 10 publications

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“…This gas diffusion generates a transition layer, and this is why a sharp interface is not observed in the optical images (Figure 4a,c) and in the SEM images (Figure 5a,c). This transition can be mechanically interesting as creating a density/composition gradient that can remove stress concentration point and properties discontinuities as reported for density gradient materials (DGM) [19]. growth in the outer layer (close to the mold wall) from the heterogeneous nucleating effect of the fibers acting as nucleating agents [8,33,34].…”

Section: Morphologymentioning

confidence: 99%

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Morphological and Mechanical Properties of Bilayers Wood-Plastic Composites and Foams Obtained by Rotational Molding

et al. 2020

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In this work, the suitability for the production of sustainable and lightweight materials with specific mechanical properties and potentially lower costs was studied. Agave fiber (AF), an agro-industrial waste, was used as a reinforcement and azodicarbonamide (ACA) as a chemical blowing agent (CBA) in the production of bilayer materials via rotational molding. The external layer was a composite of linear medium density polyethylene (LMDPE) with different AF contents (0–15 wt %), while the internal layer was foamed LMDPE (using 0–0.75 wt % ACA). The samples were characterized in terms of thermal, morphological and mechanical properties to obtain a complete understanding of the structure-properties relationships. Increases in the thicknesses of the parts (up to 127%) and a bulk density reduction were obtained by using ACA (0.75 wt %) and AF (15 wt %). Further, the addition of AF increased the tensile (23%) and flexural (29%) moduli compared to the neat LMDPE, but when ACA was used, lower values (75% and 56% for the tensile and flexural moduli, respectively) were obtained. Based on these results, a balance between mechanical properties and lightweight can be achieved by selecting the AF and ACA contents, as well as the performance and aesthetics properties of the rotomolded parts.

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Section: Morphologymentioning

confidence: 99%

“…For rotomolded foamed materials [19], several investigations have been published due to the interesting change in mechanical properties and density. Moscoso et al [20] produced a foamed single-layer material based on LMDPE using azodicarbonamide (ACA) as a chemical blowing agent (0 to 1 wt %).…”

Section: Introductionmentioning

confidence: 99%

Morphological and Mechanical Properties of Bilayers Wood-Plastic Composites and Foams Obtained by Rotational Molding

et al. 2020

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“…It is found higher than unity when the density profile decreases. In contrast, the ratio is below unity when the density profile increases with position . Accordingly, a decrease in the density profile and a flexural modulus ratio above unity for samples 16 and 17 result in lower tensile modulus.…”

Section: Resultsmentioning

confidence: 93%

“…This fact is better grasped by considering the flexural modulus ratio: E b / E u . Depending on the density distribution, the modulus ratio can be higher or lower than unity . It is found higher than unity when the density profile decreases.…”

Section: Resultsmentioning

confidence: 97%

Impact of compression molding conditions on the thermal and mechanical properties of polyethylene

Shamloo

Fathi

Elkoun

et al. 2017

J of Applied Polymer Sci

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Compression molding is a current technique in polymer processing. Despite numerous studies, effect of molding pressure on physical properties has surprisingly not been fully investigated. In this study, the thermal and mechanical behavior of the compression-molded polyethylene were thus explored to better grasp the relationship between processing parameters and ensuing properties. The effect of the molding temperature, pressure, cooling rate, and temperature profile on the tensile and flexural moduli as well as melting point of polyethylene was studied. We conclude that higher tensile and flexural moduli are obtained by increasing pressure and molding temperature, as well as decreasing the cooling rate. Our results were corroborated by X-ray diffraction and differential scanning calorimetry measurements. Moreover, the use of a temperature gradient with different temperatures for the upper and bottom plates of the mold leads to asymmetric samples whose tensile and flexural moduli are improved. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46176.

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“…For example, experimental correlations relating density profiles and mechanical properties, such as tensile and flexural properties, have been published. 4,12 -15 On the other hand, numerical studies have also been conducted for multiphysical modelling of foams with predefined morphologies. 16 -18…”

Section: Introductionmentioning

confidence: 99%

Density graded polyethylene foams: Effect of processing conditions on mechanical properties

et al. 2019

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Uniform foams (UF) and density graded foams (DGF) were produced by using similar or different temperatures on both sides of a compression molding system. The samples were produced using linear low density polyethylene as the matrix and activated azodicarbonamide as the chemical blowing agent. Morphological properties of the produced samples were analyzed via scanning electron microscopy to relate them to their mechanical properties. In particular, flexural and impact properties are reported for samples produced under a range of temperatures (140–200°C) and blowing agent concentration (0.7–1.0 wt%). The experimental results showed that a significant difference can be obtained in flexural modulus (up to 17%) and impact strength (up to 48%) depending on the side the stress is applied on. In all cases, the DGF showed better mechanical responses than UF of similar relative density for the range of conditions tested.

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Compression Molding of Polyethylene Foams under a Temperature Gradient: Morphology and Flexural Modulus

Cited by 9 publications

References 10 publications

Morphological and Mechanical Properties of Bilayers Wood-Plastic Composites and Foams Obtained by Rotational Molding

Morphological and Mechanical Properties of Bilayers Wood-Plastic Composites and Foams Obtained by Rotational Molding

Impact of compression molding conditions on the thermal and mechanical properties of polyethylene

Density graded polyethylene foams: Effect of processing conditions on mechanical properties

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