Textile Bursting Strength Test —— Film Bursting Strength Tester Method（ASTM D3786）

Scope of application

1.1 This test method is applicable to the hydraulic swelling strength tester or pneumatic diaphragm swelling strength tester to test the swelling resistance of textiles. This method is usually applied to a wide range of textile products.

1.2 This method is also applicable to elastic woven fabrics or industrial woven fabrics, such as airbags. Because new materials may exceed the range of the instrument, please refer to the report section and consider using test method D3787 or D6797 instead.

1.3 The numerical units in this specification are expressed in both the Imperial and International Systems of Units. The values expressed in each unit system are not exactly equal; therefore, each unit system should be used independently. Mixing the two systems of units may lead to inconsistent results.

Note 1: For testing the expansion strength by means of steel ball expansion, see Test Method D 3787.

1.4 This standard does not address all possible safety issues related to its use, and users of this standard are responsible for establishing appropriate safety and health practices and determining the scope of the application prior to use.

1.5 This standard county is based on the internationally recognized standard establishment principles “international standards preparation, guidance and recommended specifications principles” for the revision, which is issued by the World Trade Organization Committee on Technical Barriers to Trade.

 

References

2.1 ASTM standard:

D123 Textile-related terms

D1776 Standard Practice for Conditioning and Testing of Textiles

D3787 Standard test method for textile swelling strength – Constant velocity traction (CRT) steel ball swelling test

D4850 Terminology related to textiles and their test methods

D6797 Standard Test Method for Determination of Fixed Elongation Rate (CRE) by Spherical Explosion Test Standard Test Method for Crushing Resistance of Textiles

2.2 Other standards.

TAPPI method T403, paper bursting strength

 

Terminology

3.1 All terms related to D13.59, fabric test methods, see D4850 Terminology section

3.1.1 This standard also includes terms related to bursting strength, knitted fabrics, non-woven fabrics, stretch fabrics, and woven fabrics.

3.2 For other terms covered in this standard, please refer to D 123.

Test method overview

4.1 The sample is clamped to an expandable film. The film is hydraulically pushed to expand until the sample breaks. The difference between the pressure required to expand the sample and the pressure required to expand the film is recorded as the expansion force.

 

Meaning and use

5.1 This method is used to determine the bursting strength of knitted, non-woven, and woven films and is widely used by the textile industry for the evaluation of textiles for various applications.

5.2 In some cases, the test results obtained by applying the procedure in Test Method D 3786 do not correlate with the actual properties of the material. Test Method D 3786 is considered to be suitable for acceptance testing of bursting strength in commercial shipments of textiles and is therefore already widely used for acceptance testing in trade. In case of disagreement between buyers and sellers with different values according to test method D 3786, a random sample of the material evaluated is compared between the laboratories of the buyer and the seller to determine whether statistical deviations exist.

Note 2: The force transfer and stretching that occurs when knitted goods and non-fabrics are broken can be prevented by the clamping method described in this test method.

Equipment and materials

6.1 Hydraulic film bursting tester(See Figure 1) – test apparatus conforming to the requirements of 6.1.1 – 6.1.4. Take care to avoid externally induced vibrations during installation.

Figure 1 Hydraulic film bursting tester

6.1.1 Fixture to ensure that the test sample is fastened between two rings of parallel durable stainless steel plate surfaces and that there is no slippage during the test. Apply sufficient pressure to minimize actual slippage. The upper and lower fixture surfaces have coaxial holes with a diameter of 31 to 0.75 mm (1.22 to 0.03 in.). The surfaces of the fixture should be durable enough, and the edges that are prone to cutting action should be made into curved surfaces with a radius of curvature of not more than 0.4 mm. The lower fixture is combined with an airtight container in which the pressure medium expands the rubber film.

Note 3: Since the fixture unit and the fixture surface are subject to considerable wear and deformation, they should be inspected and repaired regularly and replaced if necessary. The resulting effect of grooving the fixture surface as specified is uncertain.

6.1.2 Film – is made of synthetic or natural rubber and is sandwiched between the fixture plate and the instrument. The central area of its upper surface remains parallel to the plate until it is stretched by pressure compression. The film should be inspected periodically and replaced as necessary.

6.1.3 Manometers – The equipment is equipped with a pressure measuring system accurate to 1% of the maximum range over the entire range. For equipment equipped with Bolden-type manometers, the measurement range is 25% to 75% of the maximum.

6.1.4 Pressure system – increase the pressure under the film until the specimen ruptures. Pressure can be obtained in two ways: hydraulically and pneumatically.

6.1.4.1 Hydraulic System – Hydraulic pressure is generated by a stream of water flowing at 95 ± 5 mL/min. The variable position of the stream is controlled by a piston in the pressure-regulating chamber of the device. The recommended fluid for the valve chamber is USP chemically pure 96% propanetriol.

Note 4: Glycol can be used in place of propylene glycol if desired.

6.1.4.2 Air pressure is generated by controlling a stream of clean, dry air using a control valve.

6.1.5 Calibrate the aluminum sheet used for the tester – use a sheet that has been determined to have an expansion force in the range of 70-790kPa (10 to 115psi)

to check the working performance of the tester.

Note 5: It may not be advisable to use aluminum sheets from one manufacturer on testers from other manufacturers. Verification should be confirmed according to the instructions for use provided by the manufacturer.

6.1.6 Pressure recording table

6.1.6.1 Hydraulic equipment – A suitable method should be found to stop pressurization at the moment the sample is damaged and to ensure that the pressure in the valve chamber is constant, which will ensure that the recording of the expansion pressure and the pressure required to expand the film is completed successfully.

6.1.6.2 Air pressure device – Measures should be taken to record the load pressure when the sample is damaged. and record the pressure required to expand the film to the same extent.

Sampling

7.1 lot sample – as a lot sample for acceptance testing, a certain number of rolls of fabric are randomly selected from the list in accordance with the applied material specification or other agreement between the buyer and seller. The number of fabric rolls is considered the basic sampling unit.

NOTE 6 A specification or agreement between the buyer and seller must take into account a combination of fabric rolls between and from the samples taken

The differences between the test samples are taken so that the sampling plan can reduce producer and consumer risk and achieve acceptable quality levels and limited quality levels.

7.2 Laboratory Samples – As a laboratory sample for the acceptability test, after discarding the first 1m length of fabric, take a full width of 1m (1yd) from each roll of fabric in the lot, along the fabric edge, or cut a long strip at least 305mm (1ft) wide from the roll or sheet portion of the circular knit fabric.

7.3 Test Samples – Take 10 square test samples of 125mm (5in.) side length from each laboratory sample.

 Calibration

8.1 Daily Calibration of Test Apparatus – The operation of the test apparatus shall be verified periodically (e.g., monthly), which may be done by expanding and breaking five standard aluminum samples. The average value of the swelling resistance shown by the five aluminum samples should be within ±5% of the standard value noted on the aluminum package. The use of aluminum sheets for verification does not apply to all test instruments. Reference should be made to the instructions provided by the manufacturer for the different instruments to be tested.

8.2 Calibration of Manometers – Calibrate manometers by means of a piston-type fixed load tester or mercury column according to the angle used previously. Alternatively, use a tracer electronic manometer or other calibration instrument recommended by the equipment supplier. This calibration is better suited to be performed in the normal position of the tester.

8.3 If there is no protocol, check the instrument in accordance with Method TAPPI Method T403 given by the American Technical Association of the Pulp and Paper Industry.

Note 7: Causes of small readings may be manometer error (deviation or non-linear error), the too rapid expansion of the manometer, too much friction on the manometer pointer, air entering the pressure system or the manometer, the membrane not being able to be zeroed, or too low a pumping rate (manual testers). Possible causes of large readings are manometer error (non-linear error), loose pointer (excessive), stop bolt bending the manometer pointer, insufficient clamping force (slippage), uneven clamping force (partial slippage), stiff or inelastic film, film above the fixture plate at zero, multiple piece testing, pumping rate too fast (manual tester) and double expansion. If the manometer accidentally exceeds its maximum range, be sure to recalibrate it before using it again.

Humidity adjustment

9.1 Follow specification D1776 to get the sample (or laboratory sample) from the regular environment to the standard environment for moisture conditioning.

Selection and quantity of specimens

10.1 Unless otherwise agreed, take 10 test specimens, each in a circle with a side length of at least 125 mm (5 in), on the laboratory sample in accordance with the Applied Materials Specification standard. The samples are tested without shearing. Samples of knitted fabrics are taken so that different samples contain different rows or rows of yarns and the distance from the edge of the fabric is not less than one-tenth of the width of the fabric. This restriction does not apply to tubular knitted fabrics.

Test Procedure of Textile Bursting Strength Test

11.1 Test all wetted test samples under the standard conditions described in 9.1.

11.2 Manual Hydraulic Tester:

11.2.1 Insert the sample under the tripod so that the sample fits snugly on the plate so that the handle clamps the sample placed on the plate as far to the right as possible.

Note 8: For samples with high elasticity, it is necessary to spread the sample evenly on the plate to remove some of the elasticity before clamping.

11.2.2 Turn the handwheel clockwise at 120 pm until the sample expands and breaks.

11.2.3 Stop the handwheel rotation as soon as the sample is found to be broken (see Note 9).

11.2.4 Immediately after the rupture, release the clamping handle clamped on the sample. And immediately turn the wheel counterclockwise to the initial position to release the tension on the film and record the pressure required to make the film expand (diaphragm pressure). Record the total pressure to make the sample swell.

Note 9: If the dial indicates that the pressure has stopped increasing and the sample has not broken, then push the lever to remove the pressure. Record as the elasticity of the sample exceeds the dimensional limits of the tester. If the sample has slipped, discard this test result and reapply a new test sample.

11.3 Motor-driven hydraulic tester:

11.3.1 Clamp the sample between the upper and lower clamps and ensure that it is flat and free of wrinkles. Clamp the sample in place and apply pressure until the sample is damaged according to the equipment instructions.

11.3.2 Film Calibration (Sheet Pressure) – The film is expanded without a specimen using the expanded specimen setup described above, and then the pressure required to expand the film to the height of the film with the specimen is recorded as the film calibration (sheet pressure).

11.4 Air Pressure Tester.

11.4.1 Adjust the control valve of the swell tester so that the average time to swell the specimen falls within the range of (20 ± 5) s. This requires a pre-test to determine the correct setting of the control valve. Record the time required from the start of the arch until the specimen is broken.

11.4.2 Ensure that the specimen is well-clamped and will not slip out of place. Zero the recorder and place it in the proper measuring position as required. Secure the safety cover in the appropriate position according to the equipment requirements and apply pressure until the specimen is broken.

11.4.3 Film Calibration – Using the same control valve settings as above without the specimen, expand the film to the average height of expansion with the specimen and record the required pressure, i.e. “film pressure”.

Calculations

12.1 Calculate the bursting pressure for each test sample by subtracting the film pressure that stretches the film from the total pressure of the bursting sample.

12.2 Report the pressure reading for each test sample and the average for each laboratory sample and batch.

12.3 Report the model number of the bursting tester used.

Reporting

13.1 Declare that testing was performed in accordance with Test Method D3768 – Testing with a Film Expansion Tester, describing the product or material sampled and the sampling method used.

13.2 Report the swelling strength and average value in kPa (psi) for each specimen. If the fabric did not break, the report should indicate the maximum swell pressure of the equipment and that the sample did not break at this pressure.

13.3 Record the model number of the bursting tester used.

Accuracy and Deviation

14.1 Summary – Comparing the average of two sets of ten observations, there should be 95 differences per 100 cases that do not exceed the following thresholds, where both sets of observations were tested by the same skilled operator, on the same instrument and on the same sample taken arbitrarily from the same test material.

Staple yarn cylinder knitted fabric 41 kPa (6.0 psi )

Filament yarn warp-knitted knitted fabric 14 kPa (2.0 psi )

Large deviations are possible in different cases, so tests can only be performed in specific methods.

Within this limit, there are no known deviations in the procedure for testing the bursting strength of Method D 3786. 14.2-14.4 are analyzed and deviations in other cases are studied.

14.2 Interlaboratory Data – Interlaboratory test comparisons were conducted in 1977, using six arbitrarily selected fabrics with four results each, tested in each of five laboratories. three fabrics were stapling yarn cylinder knits and three were filament yarn warp knits. The differences in the swelling strength results are expressed as standard deviations, as shown in Table 1.

Note 10: The differences between the two groups of samples are mainly due to differences in yarn sources rather than differences in knitting apparatus models. However, there is no objective evidence to support this view.

Note 11: These data were obtained in the laboratory using an automatic hydraulic tester, while the accuracy of the manual tester is inconclusive.

14.3 Critical Difference – For the discrepancy cases reported in 14.2, if this difference is equal to or greater than the critical difference shown in Table 2, then there is a 95% probability level that there is a significant difference between the two observations (see Note 10).

Note 12: The critical difference values listed in the table should be considered as the overall picture, especially with regard to inter-laboratory precision. The amount of statistical inter-laboratory bias must be determined before two specialized laboratories can be declared, as well as comparisons based on recent data obtained from a random sample of the evaluated material.

14.4 Bias – The procedural bias in Test Method D 3786 is unknown because the test data for swelling is also limited to this test method.

Table 1 Differences in hydraulic expansion strength expressed as standard variance and percentage

	Single Operator Portion	In-lab portioning	Interlaboratory fractions
Staple yarn tube knitting	6.8	1.1	2.5
Warp knitting of filament yarn	2.3	3.1	2.6

 

Table 2 Critical difference in expansion pressure under the indicated conditions  psir^A

	Number of observations/average	Single Operator Accuracy	In-laboratory accuracy	Interlaboratory fractions
Staple yarn tube knitting	5	8.4	9.0	11.3
	10	6.0	6.7	9.6
	20	4.2	5.2	8.7
	40	3.0	4.3	8.1
Warp knitting of filament yarn	5	2.9	9.1	11.6
	10	2.0	8.8	11.4
	20	1.4	8.7	11.3
	40	1.0	8.7	11.3

 

^A Based on infinite degrees of freedom, the critical difference is calculated using t = 1.645.