Abstract: A polydimethylsiloxane compound terminated at one end by a branched aminoalkyl group, having the average formula ##STR1## wherein R.sup.1 and R.sup.4 are monovalent hydrocarbon groups having 1 to 20 carbon atoms, R.sup.2 and R.sup.3 are alkylene groups having at least two carbon atoms, Me is a methyl radical, m is an integer between 6 and 1,000 and n is an integer between zero and 6, is disclosed. The polydimethylsiloxane of the invention can be easily prepared by the method described and imparts improved surface properties, such as water repellency and slipperiness, to organic resins modified therewith.

Abstract: Curable fluororubber compositions comprising an organic fluororubber, an organopolysiloxane gum and an epoxy-containing organoalkoxysilane or partial hydrolyzate thereof, a reinforcing filler and an organoperoxide are characterized by excellent roll workability during roll milling and can be cured to yield a fluororubber which undergoes little deterioration in its mechanical properties at low temperatures.