1.1 This part of ISO 25137 establishes a system of designation for sulfone polymer moulding and extrusion materials, including polysulfone (PSU), polyethersulfone (PESU) and polyphenylsulfone (PPSU), which may be used as the basis for specifications. 1.2 The types of sulfone polymer materials are differentiated from each other by a classification system based on appropriate levels of the designatory properties a) temperature of deflection under load, b) melt mass-flow rate, c) Charpy notched impact strength, d) tensile modulus and e) yield stress, and on information about composition, intended application and/or method of processing, important properties, additives, colorants, fillers and reinforcing materials. 1.3 This part of ISO 25137 is applicable to all sulfone polymers that contain ether oxygen, which is a necessary component of the polymers as in the diphenyl sulfone moiety. It applies to sulfone polymer materials ready for normal use in the form of powder, granules or pellets, unmodified or modified by colorants, additives, fillers, etc. 1.4 It is not intended to imply that materials having the same designation necessarily give the same performance. This part of ISO 25137 does not provide engineering data, performance data or data on processing conditions which may be required to specify a material for a particular application and/or method of processing. If such additional properties are required, they shall be determined in accordance with the test methods specified in Part 2 of this International Standard, if suitable. 1.5 In order to specify a thermoplastic material for a particular application or to ensure reproducible processing, additional requirements may be given in data block 5 (see 3.1).