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Swift Heavy Ion Induced Modification of Aliphatic Polymers

Hossain, Umme Habiba (2015):
Swift Heavy Ion Induced Modification of Aliphatic Polymers.
Darmstadt, DE, Technische Universität Darmstadt, TU Darmstadt,
[Ph.D. Thesis]

Abstract

In this thesis, the high energy heavy ion induced modification of aliphatic polymers is studied. Two polymer groups, namely polyvinyl polymers (PVF, PVAc, PVA and PMMA) and fluoropolymers (PVDF, ETFE, PFA and FEP) were used in this work. Polyvinyl polymers were investigated since they will be used as insulating materials in the superconducting magnets of the new ion accelerators of the planned International Facility for Antiproton and Ion Research (FAIR) at the GSI Helmholtz-Centre of Heavy Ion Research (GSI) in Darmstadt. In order to study ion-beam induced degradation, all polymer foils were irradiated at the GSI linear accelerator UNILAC using several projectiles (U, Au, Sm, Xe) and experimentation sites (beam lines X0 and M3) over a large fluence regime (1×1010 – 5×1012 ions/cm2). Five independent techniques, namely infrared (FT-IR) and ultraviolet-visible (UV-Vis) spectroscopy, residual gas analysis (RGA), thermal gravimetric analysis (TGA), and mass loss analysis (ML), were used to analyze the irradiated samples. FT-IR spectroscopy revealed that ion irradiation led to the decrease of characteristic band intensities showing the general degradation of the polymers, with scission of side groups and the main backbone. As a consequence of the structural modification, new bands appeared. UV-Vis transmission analysis showed an absorption edge shift from the ultraviolet region towards the visible region indicating double bond and conjugated double bond formation. On-line massspectrometric residual gas analysis showed the release of small gaseous fragment molecules. TGA analysis gave evidence of a changed thermal stability. With ML analysis, the considerable mass loss was quantified. The results of the five complementary analytical methods show how heavy ion irradiation changes the molecular structure of the polymers. Molecular degradation mechanisms are postulated. The amount of radiation damage is found to be sensitive to the used type of ionic species. While the irradiation of polymers with high energy heavy ions represents a enforced simulation test of the radiation damage in accelerators, they correspond to real situation in space where devices are directly being hit by very high energy heavy ions.

Item Type: Ph.D. Thesis
Erschienen: 2015
Creators: Hossain, Umme Habiba
Title: Swift Heavy Ion Induced Modification of Aliphatic Polymers
Language: English
Abstract:

In this thesis, the high energy heavy ion induced modification of aliphatic polymers is studied. Two polymer groups, namely polyvinyl polymers (PVF, PVAc, PVA and PMMA) and fluoropolymers (PVDF, ETFE, PFA and FEP) were used in this work. Polyvinyl polymers were investigated since they will be used as insulating materials in the superconducting magnets of the new ion accelerators of the planned International Facility for Antiproton and Ion Research (FAIR) at the GSI Helmholtz-Centre of Heavy Ion Research (GSI) in Darmstadt. In order to study ion-beam induced degradation, all polymer foils were irradiated at the GSI linear accelerator UNILAC using several projectiles (U, Au, Sm, Xe) and experimentation sites (beam lines X0 and M3) over a large fluence regime (1×1010 – 5×1012 ions/cm2). Five independent techniques, namely infrared (FT-IR) and ultraviolet-visible (UV-Vis) spectroscopy, residual gas analysis (RGA), thermal gravimetric analysis (TGA), and mass loss analysis (ML), were used to analyze the irradiated samples. FT-IR spectroscopy revealed that ion irradiation led to the decrease of characteristic band intensities showing the general degradation of the polymers, with scission of side groups and the main backbone. As a consequence of the structural modification, new bands appeared. UV-Vis transmission analysis showed an absorption edge shift from the ultraviolet region towards the visible region indicating double bond and conjugated double bond formation. On-line massspectrometric residual gas analysis showed the release of small gaseous fragment molecules. TGA analysis gave evidence of a changed thermal stability. With ML analysis, the considerable mass loss was quantified. The results of the five complementary analytical methods show how heavy ion irradiation changes the molecular structure of the polymers. Molecular degradation mechanisms are postulated. The amount of radiation damage is found to be sensitive to the used type of ionic species. While the irradiation of polymers with high energy heavy ions represents a enforced simulation test of the radiation damage in accelerators, they correspond to real situation in space where devices are directly being hit by very high energy heavy ions.
Place of Publication: Darmstadt, DE
Publisher: Technische Universität Darmstadt
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Material Analytics
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 18 Jan 2015 20:55
URL / URN: http://tuprints.ulb.tu-darmstadt.de/4333
URN: urn:nbn:de:tuda-tuprints-43330
PPN:
Referees: Ensinger, Prof. Dr. Wolfgang ; Rehahn, Prof. Dr. Matthias
Refereed / Verteidigung / mdl. Prüfung: 16 December 2014
Alternative Abstract:
Alternative abstract Language

In dieser Arbeit wird die Veränderung aliphatischer Polymere durch hochenergetische Schwerionenbestrahlung untersucht. Zwei Polymergruppen, nämlich Polyvinyl-Polymere (PVF, PVAc, PVA und PMMA) und Fluor-Polymere (PVDF, ETFE, PFA und FEP) wurden betrachtet. Polyvinyl-Polymere werden als Isolationsmaterial in supraleitenden Magneten der geplanten internationalen Beschleuniger-Anlage Forschung mit Antiprotonen und Ionen (FAIR) an der GSI Helmholzzentrum für Scherionenforschung Verwendung finden. Um die ioneninduzierten Änderungen zu studieren, wurden alle Polymerfolien am Linearbeschleuniger UNILAC an der GSI bestrahlt. Um die Degradation untersuchen zu können, wurden verschiedene Ionensorten (U, Au, Sm, Xe), Experimentierstände (Strahlzweige X0 und M3) und ein weiter Ionen-Fluenz-Bereich (1×1010 – 5×1012) Ionen/cm2 genutzt. Fünf unabhängige Techniken, Infrarot (FTIR) – und (UV-Vis) Spektroskopie, Restgasanalyse (RGA), Thermogravimetrie (TGA) und Massenverlustanalyse (ML), dienten zur Untersuchung der Materialveränderungen. Durch die FT-IR-Spektroskopie konnte nachgewiesen werden, dass die Ionenbestrahlung zu einem Rückgang der charakteristischen Banden führt, die durch Abbau der Polymere hervorgerufen wird, mit Abspaltung der Seitenketten und Bruch des Polymerrückgrats. Als Konsequenz der strukturellen Änderung erschienen neue Banden. UV-Vis Absorptionsspektrometrie zeigt eine Verschiebung der Absorptionskante vom ultravioletten Spektralbereich ins Sichtbare, welcher auf die Entstehung von Doppelbindungen und konjugierten Doppelbindungen hinweist. On-line Restgasanalyse zeigt, dass als Fragmente kleine Gasmoleküle freigesetzt werden. TGA weist auf veränderte thermische Eigenschaften hin. Mit ML wurde der erhebliche Massenverlust quantifiziert. Die Ergebnisse der fünf unterschiedlichen analytischen Methoden zeigen, wie die Ionenstrahlung zu einer Veränderung der molekularen Struktur führt. Dazu werden molekulare Degradationsmechanismen postuliert. Die Höhe der Strahlungsschäden ist dabei abhängig von der Art der Ionensorte. Während die Bestrahlung von Polymeren mit hochenergetischen schweren Ionen für Beschleunigeranlagen eine forcierte Testsituation darstellt, treten diese Bedingungen im Weltall an Geräten direkt auf, da diese dort von sehr hochenergetischen Schwerionen getroffen werden.

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