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## Viscoelastic properties of cellular polypropylene ferroelectrets

- Viscoelastic properties of cellular polypropylene ferroelectrets (PP FEs) were studied at low frequencies (0.3–33 Hz) by dynamic mechanical analysis and at high frequencies (250 kHz) by laser Doppler vibrometry. Relaxation behavior of the in-plane Young’s modulus (Y´ 11~1500 MPa at room temperature) was observed and attributed to the viscoelastic response of polypropylene matrix. The out-of-plane Young’s modulus is very small (Y´33≈0.1 MPa) at low frequencies, frequency- and stress-dependent, evidencing nonlinear viscoelastic response of PP FEs. The highfrequency mechanical response of PP FEs is shown to be linear viscoelastic with Y´33≈0.8 MPa. It is described by thickness vibration mode and modeled as a damped harmonic oscillator with one degree of freedom. Frequency dependence of Y*33 in the large dynamic strain regime is described by the broad Cole-Cole relaxation with a mean frequency in kHz range attributed to the Dynamics of the air flow between partially closed air-filledViscoelastic properties of cellular polypropylene ferroelectrets (PP FEs) were studied at low frequencies (0.3–33 Hz) by dynamic mechanical analysis and at high frequencies (250 kHz) by laser Doppler vibrometry. Relaxation behavior of the in-plane Young’s modulus (Y´ 11~1500 MPa at room temperature) was observed and attributed to the viscoelastic response of polypropylene matrix. The out-of-plane Young’s modulus is very small (Y´33≈0.1 MPa) at low frequencies, frequency- and stress-dependent, evidencing nonlinear viscoelastic response of PP FEs. The highfrequency mechanical response of PP FEs is shown to be linear viscoelastic with Y´33≈0.8 MPa. It is described by thickness vibration mode and modeled as a damped harmonic oscillator with one degree of freedom. Frequency dependence of Y*33 in the large dynamic strain regime is described by the broad Cole-Cole relaxation with a mean frequency in kHz range attributed to the Dynamics of the air flow between partially closed air-filled voids in PP FEs. Switching-off the relaxation contribution causes dynamic crossover from the nonlinear viscoelastic regime at low frequencies to the linear viscoelastic regime at high frequencies. In the small strain regime, contribution of the air flow seems to be insignificant and the power-law response, attributed to the mechanics of polypropylene cell walls and closed air voids, dominates in a broad frequency range. Mechanical Relaxation caused by the air flow mechanism takes place in the sound and ultrasound frequency range (10 Hz–1MHz) and, therefore, should be taken into account in ultrasonic applications of the PP FEs deal with strong exciting or receiving signals.…

Autoren/innen: | Mate Gaal, Viktor Bovtun, Wolfgang Stark, Anton Erhard, Y. Yakymenko, Marc Kreutzbruck |
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Dokumenttyp: | Zeitschriftenartikel |

Veröffentlichungsform: | Verlagsliteratur |

Sprache: | Englisch |

Titel des übergeordneten Werkes (Englisch): | Journal of Applied Physics |

Jahr der Erstveröffentlichung: | 2016 |

Organisationseinheit der BAM: | 5 Werkstofftechnik |

5 Werkstofftechnik / 5.3 Mechanik der Polymerwerkstoffe | |

8 Zerstörungsfreie Prüfung | |

8 Zerstörungsfreie Prüfung / 8.4 Akustische und elektromagnetische Verfahren | |

Verlag: | AIP Publishing |

Jahrgang/Band: | 119 |

Erste Seite: | Article Number: 125101 |

DDC-Klassifikation: | Naturwissenschaften und Mathematik / Chemie / Analytische Chemie |

Freie Schlagwörter: | Cellular polypropylene; Ferroelectret; Viscoelastic |

Themenfelder/Aktivitätsfelder der BAM: | Analytical Sciences |

Analytical Sciences / Zerstörungsfreie Prüfung und Spektroskopie | |

DOI: | https://doi.org/10.1063/1.4944798 |

ISSN: | 0021-8979 |

ISSN: | 1089-7550 |

ISSN: | 1520-8850 |

Verfügbarkeit des Dokuments: | Datei im Netzwerk der BAM verfügbar ("Closed Access") |

Datum der Freischaltung: | 10.05.2016 |

Referierte Publikation: | Ja |

Datum der Eintragung als referierte Publikation: | 11.05.2016 |