Technical paper: Varying Si-substituents for rubber silanes

Wesseling, Germany – European Rubber Journal has published a new technical paper from Evonik Operations GmbH on the Technical Papers section of the  ERJ website.

Titled Varying Si-substituents for rubber silanes, the paper noted that the market share of silica filled tire tread compounds for passenger cars is continuously  growing.

Compared to carbon black the use of silica and silanes reduces fuel consumption but requires a more controlled mixing procedure because this is crucial for the bonding of the silane to the silica surface.

The structure of silanes is in general characterised by three different parts: a silica-reactive side with an Si-unit; a rubber-reactive moiety; and a spacer part connecting the reactive units.

Traditionally the Si-unit is substituted by three alkoxy groups like three methoxy or three ethoxy groups.

These are cleaved and released out of the compound during the mixing process and allow formation of a covalent bond between the silica surface and the silane.

So, for the controlled bonding of the silane to the silica the kind of substitution on the Si-unit is important for this chemical reaction.

A variety of different Si substituents are known and described in  literature and patents. This article focuses mainly on ethoxy groups and  alkyl polyethers as substituents.

In the paper, it is shown, that the latter allow a very efficient hydrophobation of the silica surface, reducing the agglomeration tendency of the silica.

Authors of the paper are: Dr. Oliver Klockmann, Andre Hasse, André Wehmeier, Dr. Jens Kiesewetter, Evonik Operations GmbH.