Polycarbonate compositions having improved barrier properties

Claim 1

A flame retardant, high molecular weight aromatic polycarbonate having an I.V. of 0.40-1.0 dl/g and improved water vapor transmission and gas barrier properties, said polycarbonate being represented by the general formula ##STR6## wherein Xm and Xn can each independently be a halogen, a C 1 -C 4 alkyl, and mixtures thereof provided that at least either Xm or Xn is a halogen; m and n are each 0.1-2.5 with the proviso that when either Xm or Xn is a halogen, then m plus n equal at least 0.1, but no more than about 2.5; and, W can be a member selected from the following group: (a) --(--CH 2 ) 4 wherein r is an integer of 0-10 with the proviso that when Xm and Xn are chlorine and m and n are each 1, r is 0 or 2-10; (b) ##STR7## wherein R is a member of the group consisting of C 1 -C 10 alkyl and C 6 -C 14 aryl; (c) ##STR8## wherein R and R' can each independently be the same as R in (b) above; (d) ##STR9## wherein p and q can each independently be 0-1; and (e) --0--.