The People's Republic of China textile industry standard determination of tear strength FZ / T 6 00 06-91
Method A of this standard refers to the adoption of the international standard ISO 9073-4-1989 "Textiles-Test Methods for Nonwovens-Part 4: Determination of Tear Resistance".
1 Subject content and scope of application This standard specifies two methods for determining the tear strength of nonwovens, Method A-Trapezoid Method, Method B-Drop Weight Method.
Method A-Trapezoid method is applicable to all types of non-woven fabrics.
Method B-The drop weight method is only suitable for the measurement of the tear strength of thin non-woven fabrics whose mass is below 120g / m2.
2 Reference standards
GB 6529 Standard atmosphere for humidity control and testing of textiles
GB 8170 numerical rounding rules
3 Method A-Trapezoid Method
3.1 The principle is to draw a trapezoidal strip sample, cut a certain length of cut at the midpoint of its short side as the starting point of tearing, and then clamp the trapezoid sample along the clamping line between the upper and lower clamps of the strength testing machine Within the jaws, a continuously increasing load is applied to the sample to tear the sample along the incision and gradually expand until the sample is completely torn.
3.2 Instruments
3.2.1 Constant speed traction type (CRT) strength testing machine or constant speed elongation type (CRE) strength testing machine can also be used. The arbitration test or CRE type shall prevail in case of dispute.
3.2.2 The clamp to hold the specimen must have sufficient width to allow the width of the specimen to be fully clamped. During the test, the specimen must not slip in the jaws.
3.3 There should be no obvious creases and defects on the sampled samples, samples should be taken at a distance of more than 1m from the end of the cloth, and samples of 1m length should be cut for each variety.
3.4 Preparation of samples
3.4.1 100 mm away from the edge of the fabric on the sample, and cut 10 longitudinal and transverse samples in parallel. Generally, it can be cut more than the specified number for the reserve.
3.4.2 Sample size: First cut into strips with a width of 50mm and a length of not less than 200mm.
3.4.3 Use a trapezoid template (the size of which is shown in Figure 1) to draw the trapezoid bevel on the bar, ie, the clamping line, and cut a 10 mm length perpendicular to the short side at the center of the short side of the trapezoid Of the incision.
3.5 Humidity adjustment and test of sample The standard atmosphere is pre-conditioned and adjusted according to GB 6529.
The test is conducted in the standard atmosphere specified in GB 6529, and the arbitration test uses the secondary standard atmosphere.
3.6 Test procedure
3.6.1 Before testing, correct the distance between the upper and lower clamps to 100 ± 1mm.
3.6.2 Adjust the traction speed of the lower clamp to 100mm / min.
3.6.3 Pre-test: Select the tensile range of the strength tester so that the maximum tear strength falls between 20% and 80% of the full scale (constant speed extension CRE tester is not subject to this limit).
3.6.4 Formal test: place the sample in the upper and lower clamps so that the clamping line is flush with the clamp jaw line, then tighten the upper and lower clamp screws, and pay attention to the sample in the middle of the upper and lower clamps Symmetrical position, so that the short side of the trapezoidal sample remains vertical, and finally start the strength testing machine, wait for the sample to be completely torn, and record the maximum tear strength value.
3.6.5 If the clamp screw is not tightened during the test and the specimen slides in the jaws, the test data should be eliminated. Due to the difference in the manufacturing process, the longitudinal and transverse tearing directions sometimes have a certain irregularity during the test. Any such abnormal conditions should be noted in the test report
3.7 The result represents the average value of the maximum value of the tear strength in the longitudinal and transverse directions, the unit is Newton (N), two decimal places are calculated, and one decimal place is retained after rounding according to GB 8170.
3.8 Test report
a. Test methods and instruments;
b. Sample name, code, raw material and mixing ratio;
c. Test result: The tear strength is expressed in Newton (N), and the coefficient of variation is expressed in percentage;
d. Atmospheric conditions for testing;
e. Any deviations from this standard and abnormal phenomena need to be noted.
4 B method-drop hammer method
4.1 Principle An approximately semi-circular sample is clamped on the dynamic clamp and fixed clamp of the drop-weight tearer, and between the two clamps, that is, in the middle of the sample-notch, using a fan-shaped pendulum from The impact force when the vertical position falls to the horizontal position causes the specimens in the dynamic clamp and the fixed clamp to tear quickly.
4.2 Instrument Drop-weight fabric tear strength meter.
4.3 There should be no obvious creases and defects on the sampled samples, samples should be taken at a distance of more than 1m from the end of the cloth, and samples of 0.5m length should be cut for each variety.
4.4 Preparation of samples
4.4.1 On the sample within 100mm from the edge of the cloth, cut 10 pieces of longitudinal and transverse samples with a sample line of the specified size in a parallel arrangement, and generally can be cut more than the specified number for backup .
4.4.2 The size of the sample is 92mm wide, 63mm high, the incision line length is 20mm, the specified tear length is 43mm, and the radius of curvature R is 43mm. The specific dimensions and drawing are shown in Figure 2. In addition to cutting with a template, it can also be made into a punch to prepare samples.
4.5 The standard atmosphere of the sample for humidity control and test is the same as 3.5.
4.6 Test procedure
4.6.1 Check the level of the instrument before the test, the zero-pointing state of the pointer under no load, and make necessary adjustments. Check the height of the knife edge, and the length of the incision line should meet the requirements of 20mm.
4.6.2 Pre-test: Select the appropriate range according to the actual strength, so that the test value falls within the range of 20% to 80% of the full-scale value.
4.6.3 Raise the fan-shaped pendulum to the vertical position, which is the starting position of the test, and push the pointer to the baffle, place the bottom edge of the semi-circular sample on the middle bottom position of the two clamps, and then Tighten the two clamps and press the cutter handle to make a 20mm long incision from the bottom to the center of the sample.
4.6.4 Press the pendulum baffle, the fan-shaped pendulum falls quickly and swings to the right. Because the moving clamp is connected with the pendulum, the sample is torn and broken, when the pendulum returns to the pendulum Hold it gently with your hands. At this time, pay special attention to the position where the hands cannot touch the pointer, and finally record the reading.
4.6.5 During the test, if the clamp is not tightened and it is found that the sample slips in the clamp or the tearing track deviates from the test
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