Thermoformable polycarbonate/polyester compositions and uses

The melt strength and hence the processing window of blends of polycarbonate and PBT can be enhanced without degradation in the surface appearance of the article produced when relatively minor amounts of certain selected polymers are added to the blend. For example, a composition that has a thermoforming processing window of at least 15° C. for an article having a weight that is more than 100 grams, may contain 15 to 80% by weight of a polycarbonate resin; 10 to 80% by weight of polybutylene terephthalate, and 1 to 15% by weight of a semicrystalline melt strength enhancer. The melt strength enhancer is polyethylene terephthalate (PET), polycyclohexane-dimethyl terephthalate (PCT), polycyclohexanedimethyl terephthalate glycol (PCT-G), and (poly)ethylene co 1,4 cyclohexanedimethylene terephthlate (PET-G), or a combination thereof.