Artificial Leather Tensile Strength Testing: Standards, Methods, and Technical Guide

Artificial leather tensile strength testing is a critical quality control procedure that evaluates the mechanical durability and performance of synthetic leather materials such as PVC and PU leather. This comprehensive technical guide covers testing standards, sample preparation, test procedures, and result interpretation for manufacturers, laboratories, and quality assurance professionals in the footwear, automotive, furniture, and textile industries.

Technical Overview

Artificial leather, also known as synthetic leather, is a composite material typically composed of a textile fabric substrate (such as polyester or cotton backing) coated with a polymer layer, most commonly polyvinyl chloride (PVC) or polyurethane (PU). Tensile strength testing measures the maximum pulling force that an artificial leather specimen can withstand before rupture, along with its elongation behavior under load. This test is one of the most fundamental physical performance evaluations because it directly reflects the structural integrity of both the coating layer and the fabric substrate.

During a tensile test, a specimen of standardized dimensions is clamped between two grips of a universal testing machine and stretched at a constant speed until failure. The instrument records the force-elongation curve, from which key parameters such as maximum force, tensile strength, and elongation at break are calculated. The results are used to verify compliance with product specifications, compare material formulations, and assess suitability for end-use applications where the material will experience repeated stretching, bending, and mechanical stress.

Testing Samples

PVC Artificial Leather

Polyvinyl chloride artificial leather is produced by coating or calendering PVC plastisol onto a textile backing. Samples are typically tested to verify coating adhesion strength and overall tensile performance. PVC leather samples may exhibit different behaviors depending on whether they are foamed (blown) or compact structures, so specimen identification and orientation (machine direction versus transverse direction) must be clearly recorded.

PU Artificial Leather

Polyurethane artificial leather, including both direct-coated and wet-processed variants, generally offers higher tensile strength and superior flexibility compared to PVC. PU leather samples often require testing of both dry and wet conditioned specimens, since polyurethane performance can vary under humid conditions. Wet testing involves immersing the specimen in water at a specified temperature before performing the tensile test.

Specimen Geometry and Preparation

Standard specimens are usually dumbbell-shaped (dog-bone) strips cut with a dedicated cutting die, ensuring that failure occurs within the narrow central gauge section rather than at the grips. Typical requirements include:

• Cut specimens in both the longitudinal (machine) direction and transverse (cross) direction, with a minimum of three to five specimens per direction.
• Specimen width within the gauge section is commonly 10 mm, 25 mm, or 50 mm depending on the applicable standard.
• Avoid areas containing visible defects, wrinkles, coating damage, or near the material edges.
• Condition specimens at standard atmosphere, typically 23°C ± 2°C and 50% ± 5% relative humidity, for at least 24 hours before testing.

Testing Items

The tensile strength test for artificial leather typically reports the following parameters:

• Tensile Strength (N/mm or N): The maximum force sustained by the specimen divided by the original cross-sectional area, or reported as breaking force per unit width depending on the standard.
• Breaking Force (N): The maximum force recorded at the moment of specimen rupture.
• Elongation at Break (%): The increase in gauge length at rupture expressed as a percentage of the original gauge length.
• Load at Specified Elongation (N): The force required to achieve a predetermined extension, sometimes required for elastic or semi-elastic materials.
• Failure Mode Description: Documentation of whether failure occurred in the substrate, the coating, at the coating-substrate interface, or at the grips.

Acceptance criteria vary by product grade and application. For example, general-purpose PVC artificial leather for bags may require a minimum breaking force of around 300 N in the longitudinal direction, while high-performance PU leather for footwear uppers may demand significantly higher values. Always refer to the specific product standard or customer specification for exact limits.

Testing Methods

Applicable Standards

Several international and national standards govern artificial leather tensile testing, and the choice depends on the target market and product category:

• GB/T 8948: Chinese national standard for PVC artificial leather, specifying physical performance requirements including tensile strength.
• GB/T 8949: Chinese national standard for PU artificial leather.
• ISO 1421 / DIN EN ISO 1421: Rubber- or plastics-coated fabrics — determination of tensile strength and elongation at break, widely used for coated fabrics including synthetic leather.
• ASTM D751: Standard test methods for coated fabrics, covering breaking strength and elongation using grab and strip procedures.
• JIS K 6552 / JIS L 1096: Japanese industrial standards relevant to leather-like materials and textile testing.
• ISO 3376: Tensile strength and percentage elongation of leather, sometimes referenced for comparison with genuine leather.

Test Procedure

The general test procedure using a universal testing machine is as follows:

• Verify the testing machine calibration and select an appropriate force capacity load cell so that the expected breaking force falls between 15% and 85% of the capacity range.
• Measure and record specimen dimensions, including width and thickness within the gauge section, at multiple points and calculate averages.
• Set the gauge length according to the standard, commonly 100 mm for strip specimens.
• Clamp the specimen symmetrically in the upper and lower grips, ensuring the longitudinal axis aligns with the direction of force application without slack or pre-tension errors.
• Select the crosshead speed as specified, typically in the range of 100 to 500 mm/min depending on the standard and material type.
• Start the test and continuously record force and elongation until the specimen ruptures.
• Record the maximum force, calculate tensile strength or breaking strength, and determine elongation at break.
• Repeat for all specimens, discard results from specimens that fail at the grips (if permitted by the standard), and calculate the arithmetic mean of valid results.

Instrumentation

A typical testing setup consists of a constant-rate-of-extension (CRE) universal testing machine equipped with pneumatic or manual wedge grips, an electronic force measurement system, an extensometer or crosshead displacement measurement, and data acquisition software. Grip surfaces should be smooth, serrated, or lined with appropriate material to prevent specimen slippage without causing premature failure. Regular verification of force accuracy, speed accuracy, and gauge length is required in accordance with ISO 7500-1 and ISO 9513 or equivalent calibration standards.

Applications

Tensile strength test results for artificial leather directly influence material selection, product certification, and quality control across numerous industries:

• Footwear: Uppers, linings, and insole materials must withstand repeated flexing and stretching during walking; tensile data supports durability claims and lastability assessments.
• Automotive Interiors: Seat covers, door trim, and instrument panel wraps require verified tensile performance under temperature cycling, aging, and abrasion exposure, often tested in combination with heat aging protocols.
• Furniture Upholstery: Sofa and chair coverings experience sustained tension during fabrication and use; adequate tensile strength prevents seam failure and tearing.
• Bags and Luggage: Handles, straps, and body panels are subjected to concentrated loads, making tensile and seam strength verification essential for load-bearing components.
• Garments and Accessories: Clothing, gloves, and belts made from synthetic leather require a balance of strength and elongation to maintain fit and appearance.
• Sporting Goods: Ball coverings and protective equipment use coated fabrics whose mechanical reliability is validated through tensile testing.
• Research and Development: Formulators compare resin systems, backing fabrics, and coating structures by analyzing tensile data to optimize cost, softness, and strength trade-offs.

FAQ

What is the difference between tensile strength and breaking force?

Breaking force is the absolute maximum force (in newtons) that the specimen withstands before rupture, while tensile strength normalizes this force by the original cross-sectional area or per unit width, allowing meaningful comparison between specimens of different dimensions. Both values may be reported depending on the applicable standard.

Why must specimens be tested in both machine and transverse directions?

Artificial leather is anisotropic because the textile substrate has different yarn densities and orientations in the warp and weft directions. Testing both directions ensures the material meets minimum requirements regardless of how patterns are cut and used in the final product.

What crosshead speed should be used?

The crosshead speed is specified by the governing standard, and common values range from 100 mm/min to 500 mm/min. Using the wrong speed can significantly affect results, since higher speeds generally produce higher measured breaking forces. Always apply the speed stated in the referenced test method.

Why is specimen conditioning necessary before testing?

Temperature and humidity affect the mechanical properties of both the polymer coating and the textile substrate. Conditioning at a standard atmosphere, typically 23°C and 50% relative humidity, ensures reproducible and comparable results between laboratories and test dates.

What should be done if a specimen breaks at the grips?

Failure at or near the grips often indicates stress concentration rather than true material strength. Most standards permit discarding such results and testing additional specimens, provided the percentage of discarded results remains within the limits defined by the method. Grip liners, proper clamping pressure, and reinforced specimen tabs can help reduce grip breaks.

How often should artificial leather tensile testing be performed?

Testing frequency depends on the quality control plan. Typical practice involves testing every production batch, during incoming material inspection, after any formulation or process change, and as part of periodic type testing for certification and customer audits.