ISO 7391-1:2006 establishes a system of designation for polycarbonate thermoplastic material, which may be used as the basis for specifications.The types of polycarbonate plastic are differentiated from each other by a classification system based on appropriate levels of the designatory propertiesviscosity numbermelt volume-flow rateCharpy impact strengthand on information about the intended application and/or method of processing, important properties, additives, colorants, fillers and reinforcing materials.This part of ISO 7391 is applicable to thermoplastic polyesters of carbonic acid and aromatic dihydroxy compounds. The polyester may be a homopolymer, a copolymer or a mixture of the two.It applies to materials ready for normal use in the form of powder, granules or pellets and to materials unmodified or modified by colorants, additives, fillers, etc.