ISO 20754:2018

INTERNATIONAL ISO
STANDARD 20754
First edition
2018-04
Textiles — Man-made fibres —
Determination of shape factors in
cross section
Textiles — Fibres fabriquées — Détermination des facteurs de forme
dans la section
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved

Contents  Page
Foreword .iv
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
4  Principle . 2
5  Apparatus . 2
6  Testing conditions and specimen . 2
6.1 Testing conditions . 2
6.2 Sampling . 3
6.3 Preparation of the test specimen . 3
6.3.1 Microtome method . . . 3
6.3.2 Plate method . 3
7  Testing procedure . 3
7.1 Calibration of indicating value. 3
7.2 Image capture of fibre cross-section . 3
7.3 Number of tests . 4
7.4 Shape factor in radius . 4
7.5 Shape factor in cross-section . 4
7.6 Coefficient of perimeter . 5
7.7 Degree of hollowness . 5
7.8 Coefficient of perimeters of hollowness . 6
7.9 Specific factors . 7
7.9.1 Length of contour line . 7
7.9.2 Arc radius . 7
7.9.3 Angle . 7
7.9.4 Distance between two lines . 8
8  Result . 8
9  Test report . 9
Annex A (normative) Number of additional tests .10
Foreword
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This document was prepared by Technical Committee ISO/TC 38, Textiles, Subcommittee SC 23, Fibres
and yarns.
iv © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 20754:2018(E)
Textiles — Man-made fibres — Determination of shape
factors in cross section
1  Scope
This document specifies methods for the determination of shape factors in the cross-section of man-
made fibres.
2  Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes 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 2076, Textiles — Man-made fibres — Generic names
3  Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2076 and the following 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
shape factor
radius difference between the minimum circumscribed circle and the concentric circle
internally tangent to the section
Note 1 to entry: It is expressed as a percentage of radius of the minimum circumscribed circle.
3.2
shape factor
area difference between the minimum circumscribed circle and the cross-section shape
Note 1 to entry: It is expressed as a percentage of area of the minimum circumscribed circle.
3.3
coefficient of perimeter
X
L
perimeter ratio between the cross-section shape and the circle shape in same area
3.4
degree of hollowness
area difference between the outer contour line of the cross-section and all hollow parts
Note 1 to entry: It is expressed as a percentage of area of outer contour line, used to express the shape factor of
hollow fibres.
3.5
coefficient of perimeter of hollowness
C
XL
perimeter ratio between all the hollow parts and the outer contour line
Note 1 to entry: It is used to express the shape factor of hollow fibres.
4  Principle
This method provides techniques for the assessment of the cross-sectional shape of man-made fibres,
based on contour lines, measured radii and perimeters, calculated area and other geometric quantities.
Furthermore, the method provides techniques for the calculation of specified shape factors in the cross-
sectional shape.
5  Apparatus
The usual laboratory apparatus and, in particular, the following.
5.1  Measuring microscope apparatus, which meets the following requirements:
a) stage mechanism
...