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Interaction of Poly(dimethylsiloxane) and octamethylcyclotetrasiloxane with aluminum oxides comprising different acid-base properties

 
: Kochanke, Artur; Üffing, Christoph; Hartwig, Andreas

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Polymer degradation and stability 161 (2019), pp.19-29
ISSN: 0141-3910
English
Journal Article
Fraunhofer IFAM ()
silicone; acid-base property; aluminium oxide; polymer-filler composite; aging; degradation

Abstract
Interactions between polymer matrices and inorganic mineral surfaces are especially relevant in polymer-filler composites and in adhesion science. Knowledge about underlying mechanisms at the interphase is a prerequisite for understanding functionality and aging. Therefore, interactions of poly(dimethylsiloxanes) (PDMS) and octamethylcyclotetrasiloxane (D4) with aluminum oxides comprising different acid-base properties were studied. For this purpose, thin layers of siloxanes were applied on aluminum oxides and analyzed by Raman spectroscopy and thermogravimetric analysis. It was observed that aluminum oxides are able to react with PDMS and D4 by heterolytic bond cleavage of SiO bonds, either by reactions with physisorbed water under catalysis of aluminum oxide or by direct reaction of the surface with siloxanes. Both reaction paths can yield SiOAl bonds and thus chemisorption which lead to strong interactions between siloxanes and aluminum oxides. However, the shown reaction paths concomitantly act as aging mechanisms leading to degradation of polymer.

: http://publica.fraunhofer.de/documents/N-531480.html