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Effect of ambient atmosphere on crosslinking of polysilazanes

Chavez, Ricardo and Ionescu, Emanuel and Balan, Corneliu and Fasel, Claudia and Riedel, Ralf (2011):
Effect of ambient atmosphere on crosslinking of polysilazanes.
In: Journal of Applied Polymer Science, Wiley, pp. 794-802, 119, (2), ISSN 00218995,
[Online-Edition: http://dx.doi.org/10.1002/app.32777],
[Article]

Abstract

The influence of ambient atmosphere on the crosslinking process of two commercially available polysilazanes with different molecular units in the backbone structure (one polysilazane with and one without urea units) was studied at different temperatures using oscillatory rheometry under isothermal conditions. The measurements were performed using cone/plate, plate/plate, and Couette geometries to assess the influence of the contact surface of the samples with air on their crosslinking behavior. The crosslinking process of the investigated polysilazanes in ambient atmosphere was found to occur faster than that in inert atmosphere. DSC and FTIR-spectroscopic investigations indicate that hydrolysis and polycondensation processes occur in both polysilazanes when crosslinked in air. Interestingly, the effect of moisture was found to be more pronounced in the case of the urea derivative. The evolution of the measured complex viscosity and dynamic moduli supported this finding. Furthermore, the variation of the time derivative of complex viscosity (dη*/dt) emphasizes structural changes during crosslinking of the samples which were ascribed to their contact with the ambient atmosphere. This study emphasizes the high potential of rheometry in investigating the crosslinking behavior of polymers in inert and ambient atmosphere. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Item Type: Article
Erschienen: 2011
Creators: Chavez, Ricardo and Ionescu, Emanuel and Balan, Corneliu and Fasel, Claudia and Riedel, Ralf
Title: Effect of ambient atmosphere on crosslinking of polysilazanes
Language: English
Abstract:

The influence of ambient atmosphere on the crosslinking process of two commercially available polysilazanes with different molecular units in the backbone structure (one polysilazane with and one without urea units) was studied at different temperatures using oscillatory rheometry under isothermal conditions. The measurements were performed using cone/plate, plate/plate, and Couette geometries to assess the influence of the contact surface of the samples with air on their crosslinking behavior. The crosslinking process of the investigated polysilazanes in ambient atmosphere was found to occur faster than that in inert atmosphere. DSC and FTIR-spectroscopic investigations indicate that hydrolysis and polycondensation processes occur in both polysilazanes when crosslinked in air. Interestingly, the effect of moisture was found to be more pronounced in the case of the urea derivative. The evolution of the measured complex viscosity and dynamic moduli supported this finding. Furthermore, the variation of the time derivative of complex viscosity (dη*/dt) emphasizes structural changes during crosslinking of the samples which were ascribed to their contact with the ambient atmosphere. This study emphasizes the high potential of rheometry in investigating the crosslinking behavior of polymers in inert and ambient atmosphere. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Journal or Publication Title: Journal of Applied Polymer Science
Volume: 119
Number: 2
Publisher: Wiley
Uncontrolled Keywords: polysilazanes, crosslinking, polymer rheology, viscoelastic properties
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 04 Apr 2012 11:24
Official URL: http://dx.doi.org/10.1002/app.32777
Identification Number: doi:10.1002/app.32777
Funders: Fonds der Chemischen Industrie
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