Assisted heterogeneous multinucleation and bubble growth in semicrystalline ethylene-vinyl acetate copolymer/expanded graphite nanocomposite foams: Control of morphology and viscoelastic properties
Nanocomposite foams of ethylene-vinyl acetate copolymer (EVA) reinforced by expanded graphite (EG) were prepared using supercritical nitrogen in batch foaming process. Effects of EG particle size, crosslinking of EVA chains and foaming temperature on the cell morphology and foam viscoelastic propert...
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| Format: | Article |
| Language: | English |
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Budapest University of Technology and Economics
2015-10-01
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| Series: | eXPRESS Polymer Letters |
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| Online Access: | http://www.expresspolymlett.com/letolt.php?file=EPL-0006176&mi=cd |
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| author | O. Yousefzade F. Hemmati H. Garmabi M. Mahdavi |
| author_facet | O. Yousefzade F. Hemmati H. Garmabi M. Mahdavi |
| author_sort | O. Yousefzade |
| collection | DOAJ |
| description | Nanocomposite foams of ethylene-vinyl acetate copolymer (EVA) reinforced by expanded graphite (EG) were prepared using supercritical nitrogen in batch foaming process. Effects of EG particle size, crosslinking of EVA chains and foaming temperature on the cell morphology and foam viscoelastic properties were investigated. EG sheet surface interestingly provide multiple heterogeneous nucleation sites for bubbles. This role is considerably intensified by incorporating lower loadings of EG with higher aspect ratio. The amorphous and non-crosslinked domains of EVA matrix constitute denser bubble areas. Higher void fraction and more uniform cell structure is achieved for non-crosslinked EVA/EG nanocomposites foamed at higher temperatures. With regard to the structural variation, the void fraction of foam samples decreases with increasing the EG content. Storage and loss moduli were analyzed to study the viscoelastic properties of nanocomposite foams. Surprisingly, the foaming process of EVA results in a drastic reduction in loss and storage moduli regardless of whether the thermoplastic matrix contains EG nanofiller or not. For the EVA/EG foams with the same composition, the nanocomposite having higher void fraction shows relatively lower loss modulus and more restricted molecular movements. The study findings have verified that the dynamics of polymer chains varies after foaming EVA matrix in the presence of EG. |
| format | Article |
| id | doaj-art-0798987b0d334578be2ba200f648bfbb |
| institution | DOAJ |
| issn | 1788-618X |
| language | English |
| publishDate | 2015-10-01 |
| publisher | Budapest University of Technology and Economics |
| record_format | Article |
| series | eXPRESS Polymer Letters |
| spelling | doaj-art-0798987b0d334578be2ba200f648bfbb2025-08-20T02:41:46ZengBudapest University of Technology and EconomicseXPRESS Polymer Letters1788-618X2015-10-0191093294410.3144/expresspolymlett.2015.84Assisted heterogeneous multinucleation and bubble growth in semicrystalline ethylene-vinyl acetate copolymer/expanded graphite nanocomposite foams: Control of morphology and viscoelastic propertiesO. YousefzadeF. HemmatiH. GarmabiM. MahdaviNanocomposite foams of ethylene-vinyl acetate copolymer (EVA) reinforced by expanded graphite (EG) were prepared using supercritical nitrogen in batch foaming process. Effects of EG particle size, crosslinking of EVA chains and foaming temperature on the cell morphology and foam viscoelastic properties were investigated. EG sheet surface interestingly provide multiple heterogeneous nucleation sites for bubbles. This role is considerably intensified by incorporating lower loadings of EG with higher aspect ratio. The amorphous and non-crosslinked domains of EVA matrix constitute denser bubble areas. Higher void fraction and more uniform cell structure is achieved for non-crosslinked EVA/EG nanocomposites foamed at higher temperatures. With regard to the structural variation, the void fraction of foam samples decreases with increasing the EG content. Storage and loss moduli were analyzed to study the viscoelastic properties of nanocomposite foams. Surprisingly, the foaming process of EVA results in a drastic reduction in loss and storage moduli regardless of whether the thermoplastic matrix contains EG nanofiller or not. For the EVA/EG foams with the same composition, the nanocomposite having higher void fraction shows relatively lower loss modulus and more restricted molecular movements. The study findings have verified that the dynamics of polymer chains varies after foaming EVA matrix in the presence of EG.http://www.expresspolymlett.com/letolt.php?file=EPL-0006176&mi=cdNanocompositesFoamExpanded graphiteMorphologyviscoelastic properties |
| spellingShingle | O. Yousefzade F. Hemmati H. Garmabi M. Mahdavi Assisted heterogeneous multinucleation and bubble growth in semicrystalline ethylene-vinyl acetate copolymer/expanded graphite nanocomposite foams: Control of morphology and viscoelastic properties eXPRESS Polymer Letters Nanocomposites Foam Expanded graphite Morphology viscoelastic properties |
| title | Assisted heterogeneous multinucleation and bubble growth in semicrystalline ethylene-vinyl acetate copolymer/expanded graphite nanocomposite foams: Control of morphology and viscoelastic properties |
| title_full | Assisted heterogeneous multinucleation and bubble growth in semicrystalline ethylene-vinyl acetate copolymer/expanded graphite nanocomposite foams: Control of morphology and viscoelastic properties |
| title_fullStr | Assisted heterogeneous multinucleation and bubble growth in semicrystalline ethylene-vinyl acetate copolymer/expanded graphite nanocomposite foams: Control of morphology and viscoelastic properties |
| title_full_unstemmed | Assisted heterogeneous multinucleation and bubble growth in semicrystalline ethylene-vinyl acetate copolymer/expanded graphite nanocomposite foams: Control of morphology and viscoelastic properties |
| title_short | Assisted heterogeneous multinucleation and bubble growth in semicrystalline ethylene-vinyl acetate copolymer/expanded graphite nanocomposite foams: Control of morphology and viscoelastic properties |
| title_sort | assisted heterogeneous multinucleation and bubble growth in semicrystalline ethylene vinyl acetate copolymer expanded graphite nanocomposite foams control of morphology and viscoelastic properties |
| topic | Nanocomposites Foam Expanded graphite Morphology viscoelastic properties |
| url | http://www.expresspolymlett.com/letolt.php?file=EPL-0006176&mi=cd |
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