BS EN ISO 8067:2018 pdf download – Flexible cellular polymeric materials – Determination of tear strength This document specifies two methods for the determination of the tear strength of flexible cellular polymeric materials: — method A, using a trouser test piece; — method B, using an angle test piece without a nick. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content onstitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1923, Cellular plastics and rubbers — Determination of linear dimensions ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1: Tension/compression testing machines — Calibration and verification of the force-measuring system 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https://www.iso.org/obp — IEC Electropedia: available at http://www.electropedia.org/ 3.1 tear strength R maximum force per unit thickness observed when stretching a test piece to rupture 4 Apparatus The tear strength shall be measured on a tensile-testing machine which will indicate the force at which rupture of the test piece takes place. An automatic machine should preferably be used which draws the actual curve, or a stylus or scale should be used having an indicator that remains at the point of maximum force after rupture of the test piece. The accuracy of the test machine shall be class 2 or better as defined in ISO 7500-1. 5 Test pieces 5.1 General The test pieces shall be free of voids and flow lines. Test pieces can be selected either with or without skin. 6 Number of test pieces Three test pieces shall be tested. Additional test pieces may be required if the spread of results is too great (see Clause 9) or to compensate for deviation in the progress of the tear (see 8.2). 7 Conditioning Materials shall not be tested less than 72 h after manufacture, unless it can be demonstrated that the mean results obtained at either 16 h or 48 h after manufacture do not differ by more than ±10 % from those obtained after 72 h, in which case testing is permitted...
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