Polyethylene/ethylene-vinyl acetate copolymer/nanoclay nanocomposite foams with two concurrent phase transitions in continuous extrusion process: Effects of material and processing parameters

Ghasemi, Reza; Kazemi, Reza; Hemmati, Farkhondeh; Mohammadi-Rovshandeh, Jamshid

doi:10.22068/jstc.2020.112497.1576

Document Type : Research Paper

Authors

Caspian Faculty of Engineering, College of Engineering, University of Tehran, Rezvanshar, Iran.

10.22068/jstc.2020.112497.1576

Abstract

In this research, the structure and mechanical properties of polyethylene (PE)/ethylene-vinyl acetate copolymer (EVA)/nanoclay microcellular foams obtained through extrusion physical foaming by using carbon dioxide were investigated. The effect of PE/EVA concentration, organically-modified nanoclay and temperature profile on the properties were evaluated. The foaming process of these systems has significant complexity due to the occurrence of two concurrent phase transitions including upper critical solution temperature (UCST) phase behavior of PE/EVA blends and gas phase transition in the cell nucleation and growth process. Owing to the UCST phase behavior of PE/EVA mixtures, an increment in the process temperature profile has a profound impact on the morphology and mechanical properties of the foams and results in higher miscibility of the polymeric constituents of the blends and nanocomposites. Moreover, the nanoclay compatibilization mechanism leads to better miscibility of the polymeric phases. At higher temperature profile, lighter foams with higher cell density are obtained. Increasing the EVA content in the blends improves the nanoclay dispersion state and as a result, causes an improvement in the foam structure. By increasing the temperature profile and adding nanoclay, the elastic modulus of the foams improves and worsens respectively, due to the better PE/EVA miscibility state and nanoparticle influential role in the bubble formation.

Keywords

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Polyethylene/ethylene-vinyl acetate copolymer/nanoclay nanocomposite foams with two concurrent phase transitions in continuous extrusion process: Effects of material and processing parameters

References

Volume 7, Issue 3December 2020Pages 989-999

Volume 7, Issue 3
December 2020
Pages 989-999