The present invention relates to the use of cyclic carbonates as demoulding agents for thermoplastic polycarbonates, and to the incorporation of these cyclic carbonates into the thermoplastic polycarbonates.

A thermoplastic molding composition comprising polycarbonate and a comples ester are disclosed. The ester which conforms to ##STR1## wherein p is an integer of 2 to 8, q is an integer of 7 to 13 and R and R' independently denote a C.sub.x H.sub.2x+1 -group, where x is an integer of 8 to 24, with the proviso that R is linear, was found to impart to the composition excellent mold filling and release properties.

A thermoplastic molding composition having improved release properties is disclosed. The composition contains a polycarbonate and an additive amount of an epoxy conforming structurally to ##STR1## where R is a member selected from the group consisting of glyceryl and trimethyl propyl radicals, x is 0 to 20 and R' is a C.sub.1-4 alkyl radical.

A composition for forming an article having an improved resistance to hydrolysis is disclosed. The composition comprises a polyalkylene terephthalate and/or polyester thereof, a triglyceride, an epoxy component, and a plasticizer. The polyalkylene terephthalate has terminal carboxyl groups and hydroxyl groups and internal ester linkages. The triglyceride has at least one acid component with 6 to 30 carbon atoms and at least one epoxy group for reacting with the carboxyl groups. The epoxy component has internal aromatic groups and at least one terminal epoxy group for reacting with the carboxyl groups. The plasticizer comprises an esterification product of a polyoxyalkylene glycol with 1 to 20 carbon atoms and an aliphatic carboxylic acid with 1 to 25 carbon atoms for improving melt flow properties and for reducing hydrolysis of the composition.