Room temperature vulcanizable silicone rubber compositions and process of making

A process for forming a cured one-component room temperature vulcanizable silicone rubber composition comprising:

• (a) admixing under substantially anhydrous conditions 100 parts by weight of a silanol end-stopped liquid organopolysiloxane base polymer having a viscosity of from about 200 to about 500,000 centistokes at 25.degree. C., containing an average of from 1.85 to 2.01 organic radicals per silicon atom, and containing from about 0.02% to about 2.0% silicon-bonded hydroxyl radicals, with from about 0.25 to about 2.85 parts by weight, based upon the weight of the organopolysiloxane base polymer, of a polysiloxane polyether copolymer having the formula:
• ##STR13## where R and R' are monovalent hydrocarbon radicals, R" is a lower alkyl radical, a has a value of at least 2, b has a value of from 2 to 3, inclusive, n has a value of from 2 to 4, inclusive, and x has a value of at least 5;
• (b) subjecting the mixture to a vacuum to remove moisture;
• (c) combining the mixture under substantially anhydrous conditions with from about 1.8 to about 6.0 parts by weight, based upon the weight of the organopolysiloxane base polymer, of an organotriacyloxysilane cross-linker having the formula:
• R.sup.3 Si(OY).sub.3
• where R.sup.3 is a radical selected from the group consisting of monovalent hydrocarbon radicals, halogenated monovalent hydrocarbon radicals, and cyanoalkyl radicals, and Y is a saturated monoacyl radical of a carboxylic acid;
• and
• (d) exposing the combined mixture to moisture until it cures.