1.1 This part of ISO 8986 establishes a system of designation for polybutene-1 (PB-1) thermoplastic materials which may be used as the basis for specifications. For the sake of simplicity, the designation polybutene and the abbreviation PB are used in both parts of ISO 8986. 1.2 The types of polybutene plastics are differentiated from each other by a classification system based on appropriate levels of the designatory property melt volume-flow rate and on information about basic polymer parameters, intended application and/or method of processing, important properties, additives, colorants, fillers and reinforcing materials. 1.3 This part of ISO 8986 is applicable to all butene homopolymers and to copolymers of butene with a maximum content of other 1-olefinic monomers of less than 50 % by mass and with a content of non-olefinic monomers with functional groups up to a maximum of 1 % by mass. 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. 1.4 It is not intended to imply that materials having the same designation give necessarily the same performance. This part of ISO 8986 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. 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).