Overview
ISO 9073-7:1995 is an international standard published by the International Organization for Standardization (ISO) that specifies a test method for determining the bending length of nonwoven fabrics. This method is essential for assessing the flexibility and rigidity of nonwoven textiles under their own weight. The standard includes an equation to calculate the fabric’s flexural rigidity based on the bending length measurement. It is important to note that this method applies exclusively to nonwovens and does not cover composites or laminates, which may exhibit natural torsional behavior.
Key Topics
- Scope: Provides a clear procedure for measuring the bending length of nonwoven fabrics and calculating their flexural rigidity.
- Definitions:
- Bending length: The length of a rectangular fabric strip that bends under its own weight to form a specified angle (7.1°).
- Flexural rigidity: A measure of the resistance of the fabric to bending, derived from bending length.
- Test Principle: A fabric strip is placed on a horizontal elevated plate. The free end of the strip extends beyond the plate edge and bends down under gravity. The advancing length of the fabric beyond the edge at a defined angular deflection (41.5°) is measured.
- Apparatus: Includes a level table, an elevated plate to support the fabric, and a weighted steel ruler for advancing the specimen.
- Sampling and Preparation: Specifies cutting six test samples from the fabric in both the machine direction (MD) and cross direction (CD), with careful conditioning in standard atmospheres.
- Test Procedure: Weigh the sample to find surface mass, place it on the apparatus, advance it until it deflects to the set angle, and record the length. The bending length is half the measured advancing length.
- Calculation: Use the provided equation to calculate flexural rigidity from bending length and surface mass.
- Reporting: Reports must include fabric identification, number of measurements, bending length and rigidity values for MD and CD, variation coefficients, and any deviations from procedure.
Applications
- Nonwoven Fabric Quality Control: Enables manufacturers and quality engineers to evaluate fabric stiffness, flexibility, and handle characteristics critical for product performance.
- Product Development: Assists textile engineers in designing nonwoven materials with targeted bending properties for specific uses such as medical textiles, filtration, wipes, and upholstery.
- Comparative Testing: Provides a standardized basis for comparing the bending performance of different nonwoven materials, aiding material selection.
- Regulatory Compliance: Helps ensure nonwoven products meet functional requirements and specifications set by industry or market demands.
- Research and Innovation: Supports scientific studies enhancing understanding of nonwoven fabric mechanics and improving manufacturing processes.
Related Standards
- ISO 9073-1:1989 – Textiles – Test methods for nonwovens – Part 1: Determination of surface mass
Establishes methods to measure the fabric weight, which is fundamental input for bending length testing.
- ISO 139:1973 – Textiles – Standard atmospheres for conditioning and testing
Defines the standard environmental conditions to ensure consistency and reliability in test results.
- ISO 186:1994 – Paper, board and pulps – Sampling to determine average quality
Provides guidelines on appropriate sampling techniques, useful for preparing representative textile samples.
- Other parts of ISO 9073 series – Cover additional test methods for nonwoven fabrics including thickness, tensile strength, tear resistance, liquid penetration, and drape coefficient, complementing bending length assessments.
ISO 9073-7:1995 is a critical textile standard enabling precise and reproducible measurements of bending length and flexural rigidity for nonwoven fabrics. By applying this standardized test method, industry stakeholders optimize material design, ensure product quality, and drive innovation in nonwoven textile applications worldwide.