Abstract: The moisture and gas barrier properties of an organopolysiloxane having at least two substituents which are able to undergo crosslinking reactions per molecule shall be improved. This is achieved by providing an organopolysiloxane wherein at least 10 mol % of all substituents are represented by formula (1) wherein q is an integer from 0 to 5 and R1, R2, R3 each independently are methyl or ethyl groups. Furthermore, the invention is directed to a composition based on the aforementioned organopolysiloxane and to the use of the organopolysiloxane and of the composition.

Abstract: The present invention relates to a curable organopolysiloxane composition, which comprises: (A) an organocyclosiloxane having alkenyl groups, represented by the following formula (I) wherein n=3 or 4; (B) a hydrosilicone resin of formula (II) (R1R2R3SiO1/2)m.(R4R5SiO2/2)D.(R6SiO3/2)T.