This standard is a test method for testing the quality of machine-made jute yarn and thread (hereinafter referred to as jute yarn and thread) with jute and kenaf as the main raw materials. GB 2701-1987 Test method for jute yarn and thread GB2701-1987 Standard download decompression password: www.bzxz.net

Scope of application
National Standard of the People's Republic of China
Test methods for jute yarns and threads
Jute yarns and threads --Methods of testingUDC 677.13.062
GB 2701-87
Replaces GB2701--81
This standard is a test method for testing the quality of machine-made jute yarns and threads (hereinafter referred to as jute yarns and threads) with jute and kenaf as the main raw materials.
2 Test conditions
2.1 Test the quality of jute yarns and threads. Except for the twist which shall be in accordance with GB2543-81 "Test method for yarn twist" and the breaking strength and breaking elongation which shall be in accordance with GB3916-83 "Determination of breaking strength and breaking elongation of single yarn", the rest can be carried out under normal temperature and humidity. 2.2 Standard temperature and humidity for testing (standard atmosphere for testing) The standard temperature and humidity for testing of hemp yarn and thread are 20±2℃ and 65±2% relative humidity. 3 Sampling
The acceptance and re-inspection sampling of the receiving department shall be carried out in accordance with GB2700-87 "Acceptance Regulations for Jute Yarn and Thread". 4 Fineness test
4.1 Instruments and tools
4.1.1 The circumference of the yarn frame length gauge is 1000±1 mm. 4.1.2 The sensitivity of the scale is 0.01 gram.
4.1.3 Scissors.
4.2 Test procedure
4.2.1 Use the yarn frame length gauge at a speed of 80 to 140 revolutions per minute to shake 2 small strands (each small strand sample is 20 meters long) from each of the 10 strands (balls and cylinders), for a total of 20 small strands.
Twist 20 small skeins of samples one by one on a balance and weigh them and record them. Calculate the tex of linen yarn and thread according to formula (1) and (2): Linen yarn tex = weight (g)
×1000
length (m)
water-free tex = linen yarn tex: (1+actual moisture regain) 4.2.4 According to the test results, calculate the fineness deviation using formula (3): actual water-free tex - nominal water-free tex
fineness deviation (±%) = -
nominal water-free tex
4.2.5 Calculate the fineness unevenness H (%) using the 20 values ​​obtained during the fineness test according to formula (4): H=-2 (XX) ×N)
Where: - the arithmetic mean of all test values; Approved by the Ministry of Textile Industry of the People's Republic of China on November 9, 1987 26
-×100
(1))
Implemented on April 1, 1988
GB 2701-87
X——arithmetic mean of each test value below the average value, N,—number of test values ​​below the average value; N——total number of tests.
Note: Test values ​​that are exactly equal to the average value are not counted in the values ​​below the average value. 5 Moisture regain test
5.1 Instruments and appliances
5.1.1 Constant temperature oven. The temperature control range is 105～110℃. Equipped with a balance, the sensitivity of the balance is 0.01 grams. 5.1.2 If there is no balance on the oven, there should be a sealed box and a drying dish to put the sample in and weigh it cold outside the oven. 5.2 Test procedure
5.2.1 After weighing all or part of the linen yarn and thread samples after the fineness test, put them in an oven at a temperature of 105-110℃ to dry until constant weight. If there is no balance on the oven, after the sample is dried to constant weight, it should be placed in a sealed box and cooled in a drying dish for 15 minutes before weighing it on the balance.
5.2.2 Calculate the moisture regain according to the moisture regain calculation formula. 6 Breaking strength test
Carry out according to the provisions of GB3916-83. The number of samples is 2 samples each from 10 strands (balls, cylinders), a total of 20 samples. 7 Impurity rate test
7.1 Instruments and utensils
7.1.1 The sensitivity of the balance is 0.001 grams.
7.1.2 Tweezers and a container with a smooth surface.
7.2 Test procedure
7.2.1 Take a sample of 1 meter in length from each of the 10 strands (balls and tubes). 7.2.2 Place the sample in a smooth container and remove the impurities (the fibers in the scaly skin must be separated first). 7.2.3 Weigh the impurities W and fiber weight W2 on a balance. 7.2.4
Calculate the impurity rate according to formula (5):
Impurity rate (%)
8 Twist test
Perform according to the provisions of GB2543-81. The number of samples is 2 samples from each of the 10 strands (balls and tubes), for a total of 20 samples. 9 Appearance defects
Take the skein (ball, tube) as the unit, shake it on a 60×75 cm blackboard or put it on a yarn frame, inspect it with your eyes (the coarseness and fineness can also be measured directly with a ruler or by magnifying the quantity), and evaluate its quality. The length of the linen yarn and thread for inspection can be calculated according to the actual length or formula (6): Linen yarn length (meter) =bzxz.net
Linen yarn weight (gram) × 1000
Yarn fineness (special)
When the length is 50 meters or more, it is rounded up to 100 meters, and when it is less than 50 meters, it is ignored. 10 Calculation of results
The test results of each index are represented by the arithmetic mean of all test values ​​of the test. Except for the fineness which is calculated to one decimal place, the rest are calculated to two decimal places. Then, the fineness is rounded to an integer according to the number rounding rules in Appendix C of GB1.1-81 "General provisions for the preparation of standards for standardization work"27
GB 2701-87
. The calculated figures of various percentages should be accurate to two decimal places and rounded to one decimal place according to the provisions of Appendix C of GB1.1-81. Additional notes:
This standard is drafted by Zhejiang Hemp Textile. 28
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