Edge-surface hydroxyls modification

As we have seen, silanization has been most studied in the case of silica which are considerably richer in surface hydroxyl groups, so-called silanols, than talc. Because the effectiveness of silane modification depends on the availability of silanol groups on the mineral surface, some of the silicate fillers are more amenable to silane modification than others. Hydroxyl groups are available on the edge of talc platelets, so that silane treatment is feasible and, indeed, silane treated talc grades are commercially available. Silane treatment levels are typically 0.5-1.0% on mineral weight, to be compared with the 8% recommended for the silanization of synthetic silica. 

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