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Ageing of Polymers during Processing and Usage

Polymer processing affects the chemical and physical properties of polymers through thermal, thermal-oxidative and mechanical stress. The injection moulding process also influences the morphological structure, which can influence the ageing during usage by diffusion of oxygen. During useage besides chemical degradation physical ageing can occur.

The thermal-oxidative degradation of polyamides leads to chain branching and crosslinking as well as post-condensation. During processing the atmosphere does not influence the properties of polyamide, but there are great changes due to thermal and mechanical stress. During usage heterogeneous degradation behaviour occurs due to the diffusion of oxygen. The surface of polyamides yellows, while the centre remains unchanged. Due to the oxidation in the surface post-crystallisation becomes stronger.

The thermal-oxidative degradation of polypropylene leads to chain branching only. The oxidation of polypropylene is heterogeneous. In unchanged polypropylene there are coloured, very brittle, highly oxidized parts. During processing the atmosphere shows a great influence on the properties of polypropylene, but also the temperature and the mechanical loads must be considered. During usage there is also a greater physical ageing due to oxidation of polymer.

Lesen Sie die deutsche Zusammenfassung auf Kunststoffe.de
Author
 Sonja Pongratz

Sonja Pongratz
Lehrstuhl für Kunststofftechnik (LKT)
Universität Erlangen-Nürnberg

Information

Free keywords: Ageing, Degradation, Oxidation, Polymere, Processing, Usage, Polyamide, Polypropylene
Institute / chair: Technische Fakultät der Universität Erlangen-Nürnberg
Language: German
Technical consultant for expert services: Prof. Dr.-Ing. Dr. h.c. Gottfried W. Ehrenstein (Betreuer), Prof. Dr.-Ing. Volker Altstädt
Publication year: 2000
Provider: Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de

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