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Tuning of the Rheological Properties and Thermal Behavior of Boron-Containing Polysiloxanes

Ngoumeni-Yappi, Rodrigue ; Fasel, Claudia ; Riedel, Ralf ; Ischenko, Vladislav ; Pippel, Eckhard ; Woltersdorf, Jörg ; Clade, Jürgen (2008):
Tuning of the Rheological Properties and Thermal Behavior of Boron-Containing Polysiloxanes.
In: Chemistry of Materials, 20 (11), pp. 3601-3608. ACS, ISSN 0897-4756,
[Article]

Abstract

The rheological behavior of boron-containing poly(organosiloxanes) and their thermal decomposition were studied in order to evaluate the spinnability of these preceramic polymers, which might be suitable for the production of high-temperature-resistant ceramic fibers in the SiBCO system. The polymers were synthesized by methanolysis of tris(1-(dichloro(methyl)silyl)ethyl)borane and subsequent hydrolysis of the reaction product. Three different polymers were obtained by varying the amount of water during the hydrolysis step. The degree of cross-linking and hence the viscosity of the resulting polymer increased with the amount of water as analyzed by rheological measurements. The spinnability of polymers is affected by their flow characteristics, especially by their visco-elasticity, expressed by the dynamic moduli G′ (storage modulus, indicating elastic properties) and G′′ (loss modulus, indicating viscous properties), respectively. The thermal behavior of the three samples was analyzed in situ during the pyrolysis process between room temperature and 1400 °C, and ex situ by HREM and EELS after thermal decomposition of the samples. The ceramic yield was determined to be 45 wt % for the polymer with the lowest cross-linking degree and increased up to 75 wt % in case of the highly cross-linked polymer.

Item Type: Article
Erschienen: 2008
Creators: Ngoumeni-Yappi, Rodrigue ; Fasel, Claudia ; Riedel, Ralf ; Ischenko, Vladislav ; Pippel, Eckhard ; Woltersdorf, Jörg ; Clade, Jürgen
Title: Tuning of the Rheological Properties and Thermal Behavior of Boron-Containing Polysiloxanes
Language: English
Abstract:

The rheological behavior of boron-containing poly(organosiloxanes) and their thermal decomposition were studied in order to evaluate the spinnability of these preceramic polymers, which might be suitable for the production of high-temperature-resistant ceramic fibers in the SiBCO system. The polymers were synthesized by methanolysis of tris(1-(dichloro(methyl)silyl)ethyl)borane and subsequent hydrolysis of the reaction product. Three different polymers were obtained by varying the amount of water during the hydrolysis step. The degree of cross-linking and hence the viscosity of the resulting polymer increased with the amount of water as analyzed by rheological measurements. The spinnability of polymers is affected by their flow characteristics, especially by their visco-elasticity, expressed by the dynamic moduli G′ (storage modulus, indicating elastic properties) and G′′ (loss modulus, indicating viscous properties), respectively. The thermal behavior of the three samples was analyzed in situ during the pyrolysis process between room temperature and 1400 °C, and ex situ by HREM and EELS after thermal decomposition of the samples. The ceramic yield was determined to be 45 wt % for the polymer with the lowest cross-linking degree and increased up to 75 wt % in case of the highly cross-linked polymer.

Journal or Publication Title: Chemistry of Materials
Journal volume: 20
Number: 11
Publisher: ACS
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: 16 Apr 2012 09:21
Official URL: http://dx.doi.org/10.1021/cm703137e
Identification Number: doi:10.1021/cm703137e
Funders: The authors thank the German Research Foundation (DFG) for financial support under Grants WO 482/11-2, RI 510/36-2, and CL 208/2-2.
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