ISO 9073-7:2024

Overview

ISO 9073-7:2024 - Nonwovens - Test methods - Part 7: Determination of bending length defines a laboratory method to measure the bending length of nonwoven materials and provides a formula to calculate flexural rigidity from that measurement. The procedure is specific to nonwovens and is not applicable to combination-type materials (composites or laminates) that exhibit natural twist.

Keywords: ISO 9073-7:2024, nonwovens test method, bending length, flexural rigidity, cantilever test.

Key topics and technical requirements

• Scope and definitions: Bending length is the cantilever length that bends under its own weight to an angle of 7.1°; flexural rigidity is derived from bending length and expressed in mN·cm.
• Specimen preparation: Cut specimens 25 mm × 250 mm (±1 mm) in both machine direction (MD) and cross-machine direction (CD), avoid edges/creases, condition in standard atmosphere (see ISO 139).
• Apparatus:
  • Platform: (40 ± 2) mm wide, (200 ± 2) mm long, supported ≥150 mm above table; platform supports marked with lines at 41.5°.
  • Steel rule: ~25 mm wide, 350 mm long, mass (250 ± 10) g, rubber underside.
  • Optional motorized drive for consistent rule advance; timing accurate to ±1 s.
• Procedure summary:
  • Measure mass per unit area (ISO 9073-1).
  • Place specimen on platform, advance steel rule so specimen overhangs and bends under its own weight until leading edge reaches the 41.5° plane.
  • After (8 ± 2) s read overhanging length; bending length = half the overhang.
  • Repeat measurements (four readings per specimen) and test six specimens per direction.
• Calculations and reporting:
  • Flexural rigidity G (mN·cm) computed using G = m × C × 9.81 (m = mass/area in g·m⁻², C = mean bending length in cm).
  • Report mean values, coefficients of variation, number of specimens, test conditions and any deviations.

Applications and practical value

• Quality control: Routine production testing to monitor stiffness/handle of nonwoven rolls.
• Material specification & selection: Compare flexural rigidity across nonwoven grades for filters, hygiene products, geotextiles, packaging, and medical disposables.
• R&D and product development: Optimize fabric structure, basis weight and bonding to achieve desired drape and stiffness.
• Third‑party and contract testing: Provide standardized results for supplier contracts and compliance testing.

Who should use this standard

• Textile and nonwoven manufacturers, R&D engineers, QC laboratories, test houses, product designers, and procurement specialists who need repeatable, comparable measures of nonwoven stiffness and handle.

Related standards

• ISO 139 - Standard atmospheres for conditioning and testing
• ISO 186 - Sampling to determine average quality
• ISO 9073-1 - Nonwovens - Determination of mass per unit area

For implementers, follow the full ISO 9073-7:2024 text for detailed apparatus drawings, tolerances and reporting templates.