M. Tech. Kaushik Banik

Process-induced Long-term Deformation Behavior of Injection Molded Semicrystalline Thermoplastics

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Kurzfassung in Englisch

Process-induced Long-term Deformation Behavior of Injection Molded Semicrystalline Thermoplastics

Injection molding is a very complex process because the polymer experiences a complex thermorheological history during molding that influences the molecular orientation, residual stresses, frozen-in free volume and crystallinity inside the part. These generally govern the final part properties. Therefore it is highly desirable to anticipate the effect of process parameters on the resulting microstructure and mechanical properties of the finished part in the long run. In the case of a semicrystalline thermoplastic part, the problem in understanding the deformation behavior arises from its two-phase structure and a tendency exists to concentrate primarily on the effect of the crystalline phase on the deformation behavior, while the contribution of the amorphous phase is less investigated. In this work, the influence of the processing parameters on the deformation behavior of injection molded semicrystalline thermoplastic parts, viz., syndiotactic Polystyrene (sPS) and Polybutylene terepthalate (PBT), has been monitored through creep. The resulting internal structures due to processing have been determined and the deformation behavior has been analyzed. It has been observed that only the rate of cooling shows a remarkable effect on the long-term viscoelastic behavior of an injection molded semicrystalline thermoplastic part as it influences not only the crystalline, but also the free volume fraction, whereas the different states of frozen-in orientations and pressure-induced densification have only a negligible effect. Besides, physical aging also plays an important role in the deformation behavior of the injection moldings which was manifested with the decrease in the tendency to creep. Therefore, it was suggested that the cooling rate during injection molding and the aging time can significantly affect the long-term deformation behavior of the injection molded semicrystalline thermoplastics. The results also showed that when no significant effect is observed in terms of short-term mechanical properties by changing the processing conditions, but while considering the long-term behavior they show a significant effect.

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alternativer Titel
(Deutsch)
Prozeßinduziertes Langzeitdeformationsverhalten von spritzgegossenen teilkristallinen Kunststoffen
Schlagwörter
Injection molding
Schlagwörter
Langzeitdeformationsverhalten
Schlagwörter
Molekülorientierungen
Schlagwörter
Thermoplaste
Schlagwörter
crystallinity
Schlagwörter
free volume
Schlagwörter
long-termdeformation behavior
Schlagwörter
molecular orientation
Schlagwörter
physical aging
Schlagwörter
physikalische Alterung
Schlagwörter
semicrystalline
Schlagwörter
teilkristallin
Schlagwörter
thermoplastics
Schlagwörter
thermorheological history
Schlagwörter
thermorheologische Vorgeschichte
SWD SchlagworteFreies Volumen
SWD SchlagworteKristallinität
SWD SchlagworteSpritzgießen
DDC Klassifikation620
Institution(en) 
HochschuleTU Chemnitz
FakultätFakultät für Maschinenbau
BetreuerProf. Dr.-Ing. Günter Mennig
GutachterProf. Dr.-Ing. Günter Mennig
Prof. Dr. rer. nat. Helmut Münstedt
Prof. Dr.-Ing. habil. Bernd Platzer
DokumententypDissertation
SpracheEnglisch
Tag d. Einreichung (bei der Fakultät)18.01.2006
Tag d. Verteidigung / Kolloquiums / Prüfung16.08.2006
Veröffentlichungsdatum (online)30.08.2006
persistente URNurn:nbn:de:swb:ch1-200601279
QuelleSchriftenreihe Kunststoffe; 4
ISBN3-939382-03-5
ISBN978-3-939382-03-4

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