ISO 9073 standard has different parts for testing nonwoven fabrics, with a specific method for determining mass per unit area, thickness, tensile strength and elongation, tear resistance, and bending length (also known as fabric stiffness). This article will guide you on ISO 9073-7 and the related test methods.
What is ISO 9073-7 and Why Does It Matter in the Textile Industry?
ISO 9073 part 7 is used to determine fabric bending length and flexural rigidity. It represents fabric stiffness and traceability. It helps to understand the fabric stiffness behavior and gives an idea of how the fabric can perform during processing and in end-use.
Fabric stiffness is measured using the cantilever test method under ISO 9073-7. This standard is applicable to medical textiles, hygiene products, filters, and technical nonwoven fabrics.
Key Parameters Assessed by ISO 9073-7 for Fabric Testing
The ISO 9073-7 standard determines the fabric’s bending length and flexural rigidity, which helps to understand fabric stiffness. Fabric stiffness is its resistance to bending.
Fabric Stiffness
The resistance of a fabric to bending is called fabric stiffness. It is the opposite of fabric flexibility.
Fabric Bending Length
Fabric bending length is expressed as the length of the fabric that undergoes bending due to its weight. If the bending length value is higher, then it means the fabric has more stiffness.
In this test, fabric bends its own length, so we can say it measures the interaction between fabric weight and stiffness. Fabric bending is one component of fabric drapery, and it reflects the stiffness of a fabric.
Bending length is determined by this formula = C = L ÷ 2
C = Bending Length
L = It is the overhang length of the fabric at 7.1 degree bending angle
Flexural Rigidity
Flexural rigidity is a measure of a fabric’s stiffness when two equal and opposite forces act along parallel lines on either end of a strip of unit width of fabric bent into unit curvature in the absence of any tension.
Factors Affecting Fabric Stiffness
- Fiber type
- Yarn structure
- Fabric structure
- Finish applied
Role of Fabric Thickness and Weight in Bending Behavior
Fabric thickness and weight that are determined by ISO 9073 – 1 & ISO 9073 – 2, have direct influence on the fabric bending rigidity. As the weight and thickness of fabric increase, the bending rigidity also increases.
Bending Rigidity: G = W × C3
W = Weight of fabric
C = Bending Length
Relevant Standard Test
Relevant Standard to ISO 9073-7
The ASTM D1388 standard is similar to ISO 9073 – 7. ASTM is an American standard, while ISO is a global standard. Both these standards are used to determine the bending stiffness of textiles.
Types of Test for Bending Length and Flexural Rigidity
Test for Bending length and Flexural RigidityTwo types of testing methods are used to determine fabric bending length and flexural rigidity. According to the nature of the test, these methods are used in ISO 9073 and ASTM D 1388.
- Cantilever Test
In the Cantilever test, fabric bending is determined under its own weight. It is a simple test but not suitable for limp fabrics because they tend to curl or twist.
- Heart Loop Test
In the hear loop test, a Loop is formed in the fabric strip and hung vertically. It is suitable for fabrics that tend to curl.
ISO 9073-7 vs ASTM D 1388: A Comparative Insight
The ASTM D 1388 standard measures fabric stiffness. It covers all types of fabrics, including woven, airbag, blanket, napped, knitted, layered, and pile fabrics, whether sized, coated, or resin-treated.
It is observed that ASTM D 1388 results for woven fabrics are more accurate than those for knitted fabrics; on the other hand, ISO 9073-7 is more suitable for nonwoven fabrics.
According to a 2021 survey by INDA (Association of the Nonwoven Fabrics Industry), almost 80% of nonwoven manufacturers use the ISO 9073-7 standard to determine fabric stiffness.
ISO 9073 – 7
- Gives the best results for nonwoven fabrics
- Measures bending length and flexural rigidity using the cantilever method
ASTM D 1388
- Gives the best results for woven fabrics
- It gives results with both testing methods, Cantilever & Heart Loop
Industry Preferences: When to Use ISO 9073-7 or ASTM D 1388
Industry Preferences When to Use ISO 9073-7 or ASTM D 1388Medical textiles and hygiene products use the ISO 9073-7 standard due to the application of nonwoven fabrics in surgical masks, gowns, diapers, and wipes.
The fashion and apparel sectors use the ASTM D 1388 standard due to the use of woven fabrics in clothing. The automotive industry applies both ISO 9073-7 and ASTM D 1388 due to the use of woven and nonwoven fabric composites.
Conclusion
ISO 9073 part 7 is used to determine fabric bending length and flexural rigidity. It represents fabric stiffness and traceability. It helps to understand the behavior of fabric stiffness and gives an idea of how fabric can perform during processing and in end-use.
Fabric stiffness is measured using the cantilever test method under ISO 9073-7. This standard is applicable to medical textiles, hygiene products, filters, and technical nonwoven fabrics.
FAQs
What is ISO 9073?
ISO 9073 part 7 is used to determine fabric bending length and flexural rigidity.
Why is fabric flexibility measurement important in the textile industry?
Fabric flexibility measurement helps to understand the fabric stiffness behavior and gives an idea of how the fabric can perform during processing and in end use.
What is the role of fabric thickness and weight in bending behavior?
Fabric thickness and weight are directly proportional to fabric bending and stiffness.
How is fabric stiffness measured?
Fabric stiffness is measured using the cantilever test method under ISO 9073-7. This standard is applicable to medical textiles, hygiene products, filters, and technical nonwoven fabrics.
How many types of tests are used for bending length and flexural rigidity?
Two types of testing methods are used for bending length and flexural rigidity.
- Cantilever Test
- Heart Loop Test
What is the formula for determining fabric bending rigidity?
Bending Rigidity: G = W × C3