scope:

This part of ISO 7792 establishes a system of designation for thermoplastic polyester (TP) material, which may be used as the basis for specifications. It covers polyester homopolymers for moulding and extrusion based on poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(cyclohexylenedimethylene terephthalate) (PCT), poly(ethylene naphthalate) (PEN) and other TP-types and copolyesters of various compositions for moulding and extrusion. The types of thermoplastic polyester are differentiated from each other by a classification system based on appropriate levels of the designatory properties: a) viscosity number b) tensile modulus of elasticity and on information about the intended application and/or method of processing, important properties, additives, colorants, fillers and reinforcing materials. This part of ISO 7792 is applicable to thermoplastic polyester homopolymers and copolymers. It applies to materials ready for normal use in the form of powder, granules or pellets, unmodified or modified by colorants, additives, fillers, etc. This part of ISO 7792 does not apply to the saturated polyester/ester and polyether/ester thermoplastic elastomers covered by ISO 14910.