Hydrolytically stable polycarbonate compositions

An aromatic polycarbonate composition exhibiting improved hydrolytic stability comprising in admixture an endcapped aromatic polycarbonate resin and a hydrolytically stabilizing amount of at least one stabilizing compound of the formula

• Z.sub.n Si(R.sup.3).sub.4-n
• wherein
• n is an integer from 1 to 3 inclusive;
• R.sup.3 is independently selected from hydrogen, alkyl radicals;
• substituted alkyl radicals;
• alkenyl radicals;
• cycloalkyl radicals;
• aryl radicals;
• alkaryl radicals;
• aralkyl radicals;
• divalent organic radicals which together with the silicon atom form a cyclic structure, said organic radicals being selected from divalent saturated aliphatic hydrocarbon radicals and divalent saturated aliphatic organic radicals containing carbon and oxygen atoms in the ring structure;
• OR.sup.4 radicals wherein R.sup.4 is selected from hydrogen, alkyl radicals, substituted alkyl radicals, alkenyl radicals, aryl radicals, aralkyl radicals, alkaryl radicals, cycloalkyl radicals;
• --R.sup.5 OR.sup.4 radicals wherein R.sup.5 is a divalent saturated aliphatic hydrocarbon radical or a divalent aromatic hydrocarbon radical;
• --COOR.sup.4 radicals;
• --OOCR.sup.4 radicals;
• --R.sup.5 COOR.sup.4 radicals;
• --R.sup.5 OOCR.sup.4 radicals;
• and polyether radicals.
• Z is of the formula ##STR12## wherein:
• (i) R.sup.18 through R.sup.27 are independently selected from the class consisting of hydrogen;
• alkyl radicals;
• substituted alkyl radicals;
• alkenyl radicals;
• aryl radicals;
• alkaryl radicals;
• aralkyl radicals;
• OR.sup.29 radicals wherein R.sup.29 is selected from the class consisting of hydrogen, alkyl radicals, substituted alkyl radicals, alkenyl radicals, aryl radicals, alkaryl radicals, and aralkyl radicals;
• --R.sup.30 OR.sup.29 radicals wherein R.sup.30 is a divalent saturated aliphatic hydrocarbon radical or a divalent aromatic hydrocarbon radical;
• --COOR.sup.29 radicals;
• --OOCR.sup.29 radicals;
• --R.sup.30 OOCR.sup.29 radicals;
• --R.sup.30 COOR.sup.29 radicals;
• OR.sup.31 radicals wherein R.sup.31 is selected from the class consisting of oxirane ring containing saturated aliphatic hydrocarbon radicals and oxirane ring containing aliphatic-aromatic hydrocarbon radicals;
• --R.sup.30 OOCR.sup.31 radicals;
• and --R.sup.30 COOR.sup.31 radicals;
• with the proviso that
• (ii) one of R.sup.18 through R.sup.27 is selected from the class consisting of divalent saturated aliphatic hydrocarbon radicals;
• divalent aromatic hydrocarbon radicals;
• 13 OR.sup.32 -- radicals wherein R.sup.32 is selected from divalent saturated aliphatic hydrocarbon radicals and divalent aromatic hydrocarbon radicals;
• --R.sup.30 OR.sup.32 -- radicals;
• --OOCR.sup.32 -- radicals;
• --COOR.sup.32 -- radicals;
• --R.sup.30 OOCR.sup.32 -- radicals;
• and --R.sup.30 COOR.sup.32 -- radicals.