| abstract |
Activated MnO2 is prepd. by treating an Mn cpd. in which the Mn is in valency state 2-4, with an alkali hydroxide, in aq. soln. or in solid form, at increased temp.; and, if the valency state of the Mn is 4, O2 is present. The prod. has specific surface (BET) of 2-40 (5-15) m2/g, and is used in hardening polysulphide polymers, esp. for sealing, e.g. for sealing double-glazing units. |