Polypropylene (PP) is a common thermoplastic and frequently adapted permanently with increasing requirements by adding fillers as well as reinforcing materials.
Because of incompatibility of non-polar PP and polar inorganic filler, resulting composites are brittle which has a detrimental effect on the desired properties. Improvements in mechanical properties can be reached by compatibilization, creating of chemical couplings between phases and by increasing of inhomogeneity. Thus, maleic anhydride grafted PP is used as well as reactive processing of PP in presence of peroxide radical initiators. The temperature dependence of peroxide decay as well as the dependence of radical generation rate on time are two disadvantages of peroxide induced reactive processing.
Modification of polymers with high energy electron treatment is also well known and used to form parts (after) molding as well as raw materials (pellets, powders, fibers) in solid state and at room temperature. The spatially and temporally precise input of energy is used to produce desired material properties on radical-induced chemical reactions.
Coupling of high energy electron modification of polymers and melt mixing offers a new possibility of reactive processing. In this case, radical generation is independent of temperature, can be easily controlled by beam current and kept constant over time. Absence of any crystallinity, high reaction rates as well as intensive macromolecular mobility and intensive mixing are reasons to expect novel structures and properties.
Electron beam induced reactive processing is a novel technique where chemical reactions are induced by spatial and temporal precise energy input via high energy electrons under dynamic conditions of melt mixing. This method gives the possibility to increase surface energy of polypropylene (PP) effectively as well as to generate chemical couplings between filler and PP. The process was applied to a proved system consisting of PP (38 wt%), magnesium hydroxide (MH) (60 wt%), triallyl cyanurate (TAC) (2 wt%). This composite system was successful tested in peroxide induced conventional reactive processing. Absorbed dose imparted per rotation of rotors is a new parameter controlling mechanical properties of polymer composites. Improved properties were found in tensile strength (150 %), elongation at break (175 %), and impact strength (175 %). It can be shown that chemical couplings are generated during electron induced reactive processing in comparison to only compatibilized material.:1 Einleitung 6
2 Stand der Technik 8
2.1 Werkstoffeigenschaften von Polypropylen-Kompositen 8
2.1.1 Polypropylen 8
2.1.2 Füll- und Verstärkungsstoffe 10
2.1.3 Phasengrenze und Phasenmorphologie 12
2.1.3.1 Füllstoffmodifizierung 15
2.1.3.2 PP-Modifizierung 16
2.1.3.3 Mehrkomponentensysteme 17
2.1.3.4 Ansätze aus anderen Werkstoffsystemen 18
2.2 Reaktive Aufbereitung 19
2.3 Polymermodifizierung mit energiereichen Elektronen 22
2.3.1 Einordnung und Wechselwirkungsmechanismen 22
2.3.2 Einfluss von Polymerstruktur und G-Wert 25
2.3.3 Steuerparameter 26
2.3.3.1 Parameter der chemischen Umgebung 26
2.3.3.2 Parameter der Elektronenmodifizierung 28
2.3.4 Bestrahlung von Polypropylen 32
2.3.5 Bestrahlung von partikelgefüllten Thermoplastkompositen 33
2.3.6 Bestrahlung von Füll- und Verstärkungsstoffen 33
2.4 Zusammenfassung Stand Technik 34
3 Zielstellung 37
4 Aufgabenstellung 39
5 Experimentelles 40
5.1 Anlagentechnik 40
5.1.1 Stationäre Behandlung 40
5.1.2 Elektronen induzierte reaktive Aufbereitung 41
5.1.2.1 Aufbau u. Funktionsweise 41
5.1.2.2 Parameter der Elektronen induzierten reaktiven Aufbereitung 42
5.1.2.3 Dosimetrie 44
5.2 Probenherstellung 45
5.2.1 Materialien 45
5.2.2 Aufbereitung 45
5.2.3 Prüfkörperherstellung 46
5.3 Modifizierungsparameter 47
5.4 Vorgehensweise 49
5.5 Analytische Methoden 51
5.5.1 Zugversuch 51
5.5.2 Schlagbiegeversuch (nach Charpy) 52
5.5.3 Größenausschlusschromatographie (SEC) 54
5.5.4 Dynamische Differenzkalorimetrie (DSC) 55
5.5.5 Laserbeugungsspektrometrie 57
5.5.6 Rasterelektronenmikroskopie (REM) 58
5.5.7 Fourier-Transmissions-Infrarot-Spektroskopie (FTIR) 58
5.5.8 Dynamische Kontaktwinkelmessung 59
5.5.9 Schmelzerheologische Untersuchungen von Polymerschmelzen 60
5.5.9.1 Ungefüllte Polymerschmelzen 62
5.5.9.2 Partikelgefüllte Polymerschmelzen 63
6 Ergebnisse 68
6.1 Mechanische Kompositeigenschaften 68
6.2 Matrixpolymersysteme PP und PPTAC 69
6.3 Partikelgröße und -verteilung 75
6.4 Kompatibilität 77
6.5 Phasenkopplung 82
6.6 Inhomogenität 86
6.7 Einfluss verschiedener Prozessparameter auf die mechanischen Eigenschaften 87
6.7.1 Dosis 88
6.7.2 Elektronenenergie 90
6.7.3 Bestrahlungsdauer 91
6.7.4 Aufbereitungszeit 93
6.7.5 Dosisleistung im Modifizierungsvolumen 96
7 Zusammenfassung 98
8 Ausblick 100
9 Anhang 104
10 Literaturverzeichnis 112
11 Abkürzungsverzeichnis 115
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:25517 |
| Date | 09 February 2011 |
| Creators | Volke, Sebastian |
| Contributors | Heinrich, Gert, Weidisch, Roland, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | German |
| Detected Language | English |
| Type | doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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