ISO 15040 pdf download

ISO 15040 pdf download.Composites — Prepregs — Determination of gel time 1 Scope This International Standard specifies a method for the determination of the gel time of prepregs made of continuous reinforcement impregnated with epoxy and/or unsaturated-polyester resin. The method is applicable to most prepregs with a width in the range 300 mm to 1 000 mm. It is not suitable for very narrow prepregs (for example narrow tape), nor for prepregs with a low resin content. NOTE Other methods of measuring gel time exist. These methods are based on principles which differ from those described in clause 4, and the results obtained using such methods may be different from those obtained with this International Standard. The method described below is the traditionally used one and is widely accepted, even though it may be somewhat obsolete. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 291 :1 997, Plastics — Standard atmospheres for conditioning and testing. ISO 472:1 999, Plastics — Vocabulary. ISO 8604:1 988, Plastics — Prepregs — Definitions of terms and symbols for designations . 3 Terms and definitions For the purposes of this International Standard, the terms and definitions given in ISO 472 and ISO 8604 apply. 4 Principle A test specimen is prepared by laying up square pieces cut from the prepreg sample and wrapped in an impervious film or foil. The resin is squeezed out by applying pressure to the specimen in a hot press preheated to the test temperature. The gel time of the resin is measured as the point at which it can no longer be spun or drawn into a thread. 5 Apparatus 5.1 Cutting template, made of a hard metal such as steel, or ceramic material, measuring 50 mm by 50 mm and about 2,5 mm thick. 5.2 Knife, single-edge. 5.3 Notched plate for measuring gel time, as shown in Figure 1 for example. The plate shall be sufficiently flat...