Plastic Woven Fabric Tensile Testing: Standards, Sample Preparation, Methods, and Applications

Plastic woven fabric tensile testing measures the breaking strength and elongation of woven polypropylene (PP) and polyethylene (PE) fabrics, providing critical performance data for packaging, geotextile, and industrial applications. This technical guide covers applicable standards such as ISO 13934, GB/T 3923, and ASTM D5035, along with specimen preparation, test procedures, and result interpretation. Manufacturers, suppliers, and buyers can use this information to verify fabric quality, optimize production parameters, and ensure compliance with product specifications.

Technical Overview

Plastic woven fabric is manufactured by interlacing flat tape yarns extruded from polypropylene (PP) or high-density polyethylene (HDPE) resins. The resulting fabric combines low weight, high strength-to-cost ratio, chemical resistance, and dimensional stability, which makes it the base material for woven sacks, flexible intermediate bulk containers (FIBC), tarpaulins, geotextiles, container liners, and laminated packaging films.

Tensile testing is the most fundamental mechanical evaluation for plastic woven fabric. Because the fabric carries load through oriented tape yarns, its strength is strongly direction-dependent and sensitive to weaving density, tape thickness, and draw ratio. Tensile testing quantifies the maximum force the fabric can withstand before failure in both the warp (machine) direction and the weft (cross) direction, as well as its elongation behavior under load.

Commonly applied standards include ISO 13934-1 and ISO 13934-2 (textile fabric strip and grab tensile tests), GB/T 3923.1 and GB/T 3923.2 (Chinese national equivalents), ASTM D5035 (strip test) and ASTM D5034 (grab test), ASTM D4632 (grab test for geotextiles), and ISO 10319 or GB/T 15788 for wide-width tensile testing. Product standards such as GB/T 8946 for plastic woven sacks and GB/T 10454 for FIBC specify the tensile performance requirements that the fabric must satisfy.

Testing Samples

Strip Test Specimens (Warp and Weft)

Strip specimens are rectangular strips with an effective width of 50 mm and a length sufficient to provide a gauge length of approximately 200 mm plus additional material for clamping. Specimens are cut in both the warp and weft directions, with sampling positions distributed across the full width of the fabric roll and kept at least 100 mm away from the fabric edge to avoid edge effects. A minimum of five valid specimens per direction is required, and specimens must be free of folds, creases, visible defects, and broken tapes.

Grab Test Specimens

Grab specimens are typically 100 mm wide by 200 mm long, with only the central portion of the specimen gripped by the jaws rather than its full width. This geometry evaluates the fabric's resistance to localized force concentrations and is particularly suitable for heavy, coated, or laminated woven fabrics where raveling a strip is impractical. Both warp-way and weft-way grab specimens are prepared.

Seam Strength Specimens

For finished products such as woven bags and FIBC bodies, sewn or heat-sealed joints are often the weakest point. Seam strength specimens contain a stitched seam positioned at a defined distance from the mid-point of the gauge length, so that failure occurs at the seam during extension. These specimens are prepared with the same dimensions as grab or strip specimens, depending on the referenced standard.

Wide-Width Specimens for Geotextile Applications

When plastic woven fabric is used as a geotextile for reinforcement or separation, wide-width tensile testing per ISO 10319 or ASTM D4595 is performed. Specimens are 200 mm or wider with a gauge length of 100 mm, which minimizes the influence of individual tape yarns and provides strength values expressed in kN/m suitable for engineering design.

Testing Items

The principal parameters measured during plastic woven fabric tensile testing include:

• Maximum tensile force (breaking force), reported in N for strip specimens or N/50 mm for width-normalized strength
• Tensile strength for wide-width specimens, reported in kN/m
• Elongation at break, expressed as a percentage of the initial gauge length
• Elongation at specified force, used when design load levels are defined
• Seam or joint strength for finished bag and FIBC assemblies
• Statistical dispersion of results, including coefficient of variation between replicate specimens

For typical PP woven fabric, breaking elongation commonly falls in the range of 10 to 30 percent, while breaking force depends heavily on tape denier, weave density, and lamination, often reaching several hundred to over one thousand newtons per 50 mm of fabric width.

Testing Methods

Sample Preparation and Conditioning

All specimens are cut with sharp blades to avoid nicking the tape yarns, and fabric rolls are sampled after removing the outer layers. Specimens are conditioned in a standard atmosphere before testing, typically at 23 ± 2 °C with 50 ± 10 percent relative humidity for plastic-based materials, or at 20 ± 2 °C with 65 ± 4 percent relative humidity for textile-based procedures. A conditioning period of at least 24 hours is generally applied so that temperature and moisture equilibrium is reached.

Test Procedure

Testing is performed on a calibrated universal testing machine fitted with pneumatic, hydraulic, or wedge-type grips lined with rubber or emery surfaces to prevent slippage of the smooth tape yarns. The standard procedure for the strip method is as follows:

• Set the gauge length to 200 mm for the strip method, or approximately 100 mm for grab and wide-width configurations as specified by the standard
• Select the extension rate, commonly 20 mm/min for the ISO strip method, with higher speeds of 100 to 300 mm/min used in certain grab and ASTM procedures
• Mount the specimen centrally in the grips, apply the specified pretension to remove slack without stressing the fabric, and zero the load and extension readings
• Extend the specimen until rupture and record the maximum force and elongation at break
• Discard results where the specimen breaks within the jaw line, slips in the grips, or fails at a distance less than the minimum allowed from the clamp edge, and repeat with a new specimen

Data Processing and Reporting

The arithmetic mean of all valid specimens is calculated separately for warp and weft directions, along with the coefficient of variation. Breaking force is reported in newtons or normalized to N/50 mm (or kN/m for wide-width testing), and elongation values are rounded according to the precision requirements of the standard. The test report should identify the fabric specification, sampling plan, conditioning atmosphere, machine speed, grip type, number of specimens tested, individual and mean results, and any deviations observed during testing.

Applications

Tensile testing of plastic woven fabric supports quality control and product qualification across a wide range of industries:

• Packaging: strength verification of PP woven sacks for cement, fertilizer, flour, rice, and animal feed, where fabric strength directly determines safe stacking and handling loads
• Logistics: certification of FIBC and jumbo bag body fabric and lift loops used for bulk transport of powders and granules
• Construction: qualification of woven geotextiles for soil separation, filtration, and reinforcement, and of scaffold safety netting and tarpaulins
• Agriculture: evaluation of ground cover fabric, silage covers, and greenhouse screening materials
• Transportation: assessment of container liners, cargo covers, and pallet wrap fabrics
• Manufacturing optimization: comparison of tape draw ratios, weaving parameters, and lamination processes during product development

Accredited third-party laboratories operating under ISO/IEC 17025 quality systems can perform these tests for regulatory compliance, supplier qualification, trade acceptance, and failure analysis purposes.

FAQ

Question: What is the difference between the strip method and the grab method?

Answer: The strip method clamps the full 50 mm width of the specimen, so every tape yarn across the width contributes to the measured force, giving a direct indication of intrinsic fabric strength. The grab method grips only the central region of a wider specimen, which better simulates localized loading conditions and is preferred for heavy, coated, or dense woven fabrics where raveling a strip is difficult.

Question: Why must warp and weft directions be tested separately?

Answer: Woven plastic fabric is anisotropic because the warp and weft tapes differ in linear density, drawing orientation, and weaving crimp. Warp-direction strength is frequently higher than weft-direction strength, and both values are needed to characterize fabric performance and detect weaving defects.

Question: Which testing speed should be selected?

Answer: The speed is fixed by the referenced standard. ISO strip methods typically specify 20 mm/min with a 200 mm gauge length, while several ASTM grab and strip procedures specify faster rates in the range of 100 to 300 mm/min. Consistency with the standard is essential because higher speeds generally produce higher measured breaking forces.

Question: How many specimens are required for a valid result?

Answer: At least five valid specimens per direction are required for routine fabric testing, with additional specimens prepared in anticipation of jaw breaks or slippage. Results from invalid failures are excluded and replaced so that the reported mean reflects true fabric strength.

Question: What acceptance criteria are typically applied?

Answer: Acceptance limits depend on the product specification. For example, woven sack standards define minimum breaking force in N/50 mm for each direction, and FIBC standards require minimum fabric and seam strengths corresponding to the declared safety factor of the bag. The specification agreed between buyer and seller, or the applicable product standard, governs the pass/fail decision.

Question: Can laminated or coated woven fabric be tested by the same methods?

Answer: Yes. Coated fabric is usually tested by the grab method or by the strip method with cut-strip specimens, since the coating prevents raveling. The coating may slightly increase measured force and reduce jaw slippage, so the method chosen should be documented in the test report.