ISO INTERNATIONAL STANDARD 1265 Second edition 2007-02-01 Plastics Poly(vinyl chloride) resins Determination of number of impurities and foreign particles Plastiques Résines de poly(chlorure de vinyle) Détermination du nombredimpuretesetdecorpsétrangers Reference number ISO 1265:2007(E) @ ISO 2007 ISO 1265:2007(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of preparing International Standards is normally carried out through IsO non-governmental, in liaison with isO, also take part in the work. isO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote rights. IsO shall not be held responsible for identifying any or all such patent rights. ISO 1265 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 9, Thermoplastic materials. Thissecondeditioncancelsandreplacesthefirstedition(lSO1265:1979),whichhasbeentechnicallyrevised ii ISO 1265:2007(E) Introduction Poly(vinyl chloride) resins are commonly produced as various powders that are essentially white in colour. However, the polymerization of vinyl chloride monomer into poly(vinyl chloride) uses processes that may plant and the use of heat. This International Standard describes a simple procedure for determining the number of impurities and foreign particles in a sample, with clarification of the different cases encountered (highly contaminated, heterogeneous or homogeneous contamination of the sample). iv @IS02007-All rights reserved INTERNATIONAL STANDARD ISO1265:2007(E) Plastics Poly(vinyl chloride) resins Determination of number of impurities and foreign particles Scope This International Standard specifies a method for determining the number of impurities and foreign particles divided state. 2 Principle A certain quantity of resin is flattened between a rigid plate (covered with a sheet of glazed white paper) and a glass plate containing a grid, and the number of specks (impurities and foreign particles) of size greater than 0,250 mm, i.e. clearly visible to the naked eye, is counted in 25 squares of the grid. Apparatus 3.1 Glass plate, 340 mm × 340 mm × 4,5 mm, colourless, perfectly transparent, and without defects such as stripes, bubbles or black spots.1) Mark in the centre of the surface of the glass sheet a grid measuring 300 mm × 300 mm, consisting of 100 30 mm × 30 mm squares. This grid may be drawn with an indelible pencil, a diamond or any other appropriate tool, on the face of the sheet which is not in contact with the resin. 3.2 Rigid plate, 450 mm × 450 mm, covered with a sheet of glazed white paper. 3.3 Timer (e.g. stopwatch). 4 Procedure Spread out about 200 cm3 of the test sample on the rigid plate (3.2) that it touches the glass over an area of at least 25 squares, preferably in the centre of the plate. Mark the limits of the entire 25 selected squares with a thick pencil mark (see Figure 1). eye inside the selected squares, within a period of 2 min. The selected squares shall be viewed from a distance of about 300 mm in good laboratory lighting conditions. 1) If there are any defects in the glass plate, take this into account in the determination. ISO 1265:2007(E) NOTE1 2 min is the maximum time before the operator's eyes become tired. NOTE2 A photographic reference scale is provided to indicate which particles are to be counted (see Figure 2) Repeat the counting process (giving counts of n2, n3, n4) as necessary, using a new test sample each time, acc