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Report
ISO/TR 20659-1
First edition
Rheological test methods —
2024-03
Fundamentals and interlaboratory
comparisons —
Part 1:
Determination of the yield point
Méthodes d'essai rhéologiques — Principes fondamentaux et
comparaisons interlaboratoires —
Partie 1: Détermination du seuil d'écoulement
Reference number
ISO/TR 20659-1:2024(en) © ISO 2024
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ISO/TR 20659-1:2024(en)
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© ISO 2024 – All rights reserved
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ISO/TR 20659-1:2024(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Goal of the interlaboratory test . 1
5 Metrological determination of the yield point . 2
5.1 General .2
5.2 Shear rate-controlled rotational test .2
5.3 Yield point evaluation using flow curve regression models .2
5.4 Shear stress-controlled rotational test .4
5.5 E valuation methods for yield points .4
5.5.1 General .4
5.5.2 Axis intercept for presentation of the flow curve using a linear scale .4
5.5.3 Plateau value for presentation of the flow curve using a logarithmic scale .5
5.5.4 Yield point evaluation at a reference value .5
5.5.5 Methods with regression lines for presentation in the lg γ/lg τ diagram .6
5.5.6 Rotational test: viscosity maximum method .7
5.5.7 Tests with constant shear rate .8
5.5.8 Creep test .9
5.5.9 Oscillatory test: amplitude sweep .10
6 Results of the comparative testing programme .
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