ISO 20754:2018

Textiles - Man-made fibres - Determination of shape factors in cross section

ISO 20754:2018 specifies methods for the determination of shape factors in the cross-section of man-made fibres.

Textiles — Fibres fabriquées — Détermination des facteurs de forme dans la section

General Information

• Status: Published
• Publication Date: 04-Apr-2018
• ICS: 59.060.20 - Man-made fibres
• Technical Committee: ISO/TC 38/SC 23 - Fibres and yarns
• Drafting Committee: ISO/TC 38/SC 23/WG 6 - Fibres - Man-made
• Current Stage: 9093 - International Standard confirmed
• Start Date: 25-Sep-2023
• Completion Date: 13-Dec-2025

Overview

ISO 20754:2018 - Textiles - Man-made fibres - Determination of shape factors in cross section - specifies laboratory methods to quantify the geometric shape of man‑made fibre cross‑sections. The standard defines how to prepare specimens (microtome or plate methods), capture microscope images, and calculate shape factors, perimeter coefficients, and degree of hollowness using measured radii, areas and perimeters. It is intended for use in fibre characterization, quality control and research.

Key topics and requirements

• Scope: Methods for determination of shape factors in the cross‑section of man‑made fibres.
• Specimen preparation:
  • Microtome method (slice thickness exposing fibres at about 20–30 µm) or plate method (stretched bundle through a sample plate).
  • Sampling: filaments ~0.5 m cut from a package; staple bundles ~0.5 g.
• Apparatus: measuring microscope with magnification ≥ 400×, minimum resolvable distance 1.5 µm, digital measuring stage; fibre microtome; sample plate (≈70 × 20 × 0.2–0.4 mm); stage micrometer (0.01 mm divisions).
• Testing conditions: ambient laboratory conditions are acceptable; avoid compressed edge sections.
• Image capture and testing: capture clear cross‑section images, exclude damaged or incomplete images; test at least 30 cross‑sections per slide (additional tests if confidence criteria are not met).
• Defined metrics and calculations:
  • Shape factor (radius): (R − r) / R × 100% where R = radius of minimum circumscribed circle and r = radius of concentric circle internally tangent to the section.
  • Shape factor (cross‑section): area difference expressed as percentage of the minimum circumscribed circle area.
  • Coefficient of perimeter: ratio of contour perimeter to circle perimeter for same area.
  • Degree of hollowness and coefficient of perimeters of hollowness for hollow fibres.
  • Additional specific measurements: contour length, arc radius, angles, and distances.

Applications

• Quality control and dimensional verification in textile manufacturing and fibre extrusion processes.
• Morphological analysis for R&D (fibre cross‑section design, hollow fibre evaluation).
• Comparative testing for fibre identification and specification compliance.
• Input data for fabric performance modeling where cross‑sectional geometry affects mechanical, optical or bulk properties.

Who should use this standard

• Textile testing laboratories and quality assurance teams.
• Fibre manufacturers and process engineers.
• Research scientists working on synthetic fibre morphology.
• Standards developers and conformity assessment bodies.

Related standards

• ISO 2076 (man‑made fibres - generic names) - cited normative reference in ISO 20754:2018.

Keywords: ISO 20754, man-made fibres, fibre cross-section, shape factor, degree of hollowness, measuring microscope, microtome, textile testing.

Standards Content (Sample)

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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different types of ISO documents should be noted. This document was drafted in accordance with the
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URL: www .iso .org/ iso/ foreword .html.
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
...