JB/T 7852-1995 Technical requirements for polyacrylonitrile pre-oxidized fibers for braided packing
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T7852-95
Technical conditions for polyacrylonitrile pre-oxidized fibers for braided packing
Published on December 1, 1995
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1996
Mechanical Industry Standard of the People's Republic of Chinawww.bzxz.net
Technical conditions for polyacrylonitrile pre-oxidized fibers for braided packing
1 Subject content and applicable scope
JB/T 785295
This standard specifies the technical requirements, test methods and inspection rules for polyacrylonitrile (PAN)-based pre-oxidized fibers for braided packing (hereinafter referred to as pre-oxidized fibers).
This standard applies to pre-oxidized fibers.
2 Technical requirements
2.1 The mechanical properties of pre-oxidized fibers shall comply with the provisions of Table 1. Table 1
Density g/em
1. 35~1. 45
Tensile strength MPa
≥210
Initial tensile modulus MPa
≥6000
2.2 The surface of the pre-oxidized fiber should be smooth, without obvious defects such as hair, broken ends and impurities, and not burnt. 2.3 The continuous length of the pre-oxidized fiber should be not less than 500m. 3 Test method
3.1 The test method for the density of pre-oxidized fibers shall be in accordance with the provisions of Appendix A (Supplement). Elongation at break %
3.2 The test methods for tensile strength, initial tensile modulus and elongation at break of pre-oxidized fibers shall be in accordance with the provisions of Appendix B (Supplement). 3:3 The appearance quality of pre-oxidized fibers shall be visually inspected. 4 Inspection rules
4.1 Pre-oxidized fibers shall be inspected and qualified by the inspection department of the manufacturer before they can leave the factory. 4.2 The appearance quality of pre-oxidized fibers shall be fully inspected, and the other items shall be sampled. 4.3 Sampling
4.3.1 Products of the same brand and specification are counted as one batch of 100kg. If less than 100kg, they are counted as one batch. 4.3.2 Two rolls of pre-oxidized fibers are randomly selected from the same batch of pre-oxidized fibers for sampling. When sampling, 10m of pre-oxidized fibers are taken from each roll (the first 10m on each roll is included first) as the total sample. 5 Marking, packaging, transportation and storage
5.1 Pre-oxidized fibers shall be neatly arranged on hollow paper rolls or plastic cylinders with a diameter (outer diameter) of not less than 45mm and a wall thickness of not less than 3mm, wrapped with soft and clean paper and put into mold bags, and the length, net weight, manufacturing date and batch number shall be indicated. 5.2 The packaging box of pre-oxidized fiber should indicate: product name, model and specification:
Manufacturer name and trademark;
Product quantity (abbreviation) and weight;
Approved by the Ministry of Machinery Industry on December 1, 1995
Implementation on July 1, 1996
Factory date.
JB/T 7852-95
5.3 The product packaging box should be accompanied by a product certificate, which should indicate: a. Batch number:
b. Standard number:
c. Inspector's name or code,
5.4 The product must be protected from rain, sun exposure and moisture during transportation. 5.5 The product should be stored in a clean and dry warehouse, and sun exposure and rain exposure are strictly prohibited. The storage period should not exceed three years from the date of production. 2
AI Test equipment
JB/T7852-95
Appendix A
Test method for density of pre-oxidized fibers
(Supplement)
A1.1 Ruler: 1m in length, 0.5mm in accuracy. A1.2 Balance, 0.1mg in sensitivity.
A1.3 Constant temperature drying oven: with blower, maximum temperature 200℃. A1.4 Dryer: filled with silica gel desiccant. A1.5 Beaker, 250mL.
A1.6 Bracket for supporting beaker.
A2 Test equipment
A2.1 The standard environmental conditions for the test are temperature 20±5r and relative humidity of air (60±5)%. A2.2 When the test is carried out under other conditions, the test environment temperature and relative humidity of air shall be indicated in the test report. A3 Test specimen
A3.1 Take two total test specimens according to 4.3.2. Take a test specimen every 1m from the two total test specimens. Take two sections from each total test specimen, for a total of four sections. The length of each section shall comply with the provisions of Table A1. Table A1
Nominal number of single filaments
Length of each test specimen
Test specimen length
A3.2 The surface of the test specimen shall be smooth, without defects such as hair, broken ends, knots and impurities. A3.3 The four test specimens shall be numbered to avoid loss. A4 Test steps
A4.1 Shape the test specimen into a small ring with a diameter of about 10mm, place it in a drying oven that has been kept at a constant temperature of 105±5℃ and dry it for 2h, then place it in a desiccator to cool to room temperature and weigh it.
A4.2 Tie the sample ring with a metal wire with a diameter not exceeding 0.1mm and make a mark on the metal wire. The position of this mark should ensure that the sample is still in the hanging state after being immersed in anhydrous ethanol. A4.3 Pour chemically pure anhydrous ethanol into the beaker and then place it on the bracket supporting the beaker. A4.4 Hang the metal wire that ties the sample on a balance and weigh it in the air to an accuracy of 0.1mg. Then completely immerse the sample in anhydrous ethanol, remove the bubbles on the surface of the sample by swinging, adjust the volume of anhydrous ethanol so that the liquid surface is consistent with the mark on the metal wire, and weigh it in anhydrous ethanol to an accuracy of 0.1mg.
A4.5 Remove the sample and weigh the weight of the wire in air and in anhydrous ethanol (the wire should also be set to the mark in A4.2). Accurate to 0.1mg
A4.6 Measure the density of anhydrous ethanol with a liquid density meter. A4.7 Calculate the density according to formula (A1) and express the result as the arithmetic mean of the four samples. Take two decimal places. Where: p-density of pre-oxidized fiber·g/cm: pg
m,-m,A
P—density of anhydrous ethanol+g/cm*
m—weight of the sample in air, g,
JB/T785295
m: weight of the sample in anhydrous ethanol, g. A4.8 The maximum deviation of the density measurement of the four sections of the sample taken from the two total samples should not be greater than 2%. If it exceeds 2%, the sample should be re-sampled and measured. B1 Test equipment
JB/T 785295
Appendix B
Test method for tensile strength, initial tensile modulus and elongation at break of pre-oxidized fibers (supplement)
B1.1 Optical transmission microscope: magnification 500×, cross micrometer with scale lines in the eyepiece, B1.2 Single fiber electronic strength meter: range 0~100cN, equipped with XY recorder, B1.3 Set of triangles.
B2 Test conditions
B2.1 The standard test environment is 20±5C and relative air humidity (60±5)%. B2.2 When testing under other conditions, the test environment temperature and relative air humidity should be indicated in the test report. B3 Specimen
B3.1 Take a specimen of about 100mm in length from each total specimen every 1m, and take two sections in total. B3.2 Soak the two samples in acetone for 2 hours to remove the surface protective glue. For the un-glueized samples, soak for 10 minutes. After taking them out, let the acetone evaporate naturally.
B3.3 Randomly select 15 pre-oxidized fiber singles from each sample, a total of 30, and stick them on the paper frame shown in Figure B1 with adhesive. Dry them naturally at room temperature for 24 to 48 hours, and number them for measurement. 35
Head chlorinated fiber single filaments
Bonded
Paper frame for preparing samples in Figure B1
B4 Determination of diameter
B4.1 The size corresponding to each small grid on the scale line of the microscope eyepiece micrometer is calibrated with a 0.01mm micrometer. B4.2 Place the paper frames with pre-oxidized fibers and numbers on the stage of the microscope in sequence, adjust the focus of the objective lens so that the fiber monofilament is clearly imaged in the eyepiece, and read the number of grids occupied by the fiber edge in the eyepiece micrometer scale, accurate to 0.2 grids. B4.3 Use formula (B1) to calculate the diameter of the fiber monofilament, accurate to two decimal places. d = number of grids Xd.
Where: d—diameter of pre-oxidized fiber monofilament, um#d. —the size corresponding to each grid on the microscope eyepiece micrometer scale, μm/grid. Determination of initial tensile modulus, tensile strength and elongation at break B5
B5.1 Operating procedures
JB/T7852-95
B5.1.1 Adjust the distance between the upper and lower clamps of the single fiber electronic strength meter to 25mm, adjust the descending speed of the lower clamp to 8~10mm/min, and adjust the paper feed speed of the XY recorder to 60~120mm/min. B5.1.2 Install the paper frame with the fiber monofilament with the measured diameter in sequence between the upper and lower clamps of the strength meter, and cut the two ends of the paper frame.
B5.1.3 Press the descending button, and the lower gripper will descend at a constant speed. At the same time, the XY recorder will automatically record the load-elongation curve (see Figure B2). tu
Test curve
Figure B2 Load-length drawing line
Negative point
B5.1.4 Draw two tangent lines on the load-elongation curve, including the zero negative point or the breaking load point, and intersect at point A. B5.2 Initial tensile modulus E
Read the load value P at point A and the elongation △L, and use formula (B2) to calculate the initial tensile modulus, accurate to one decimal place, 10000P./(x/4)d
Where: E—initial tensile modulus, MPa; P,—negative value corresponding to point A, cN;
d—fiber monofilament diameter + um;
AL,—length corresponding to point A, mm;
L—length of fiber monofilament sample (25mm): K—elongation correction coefficient,
lower clamp descent speed (mm/min)
Record only paper feed speed (mm/min),
B5.3 Tensile strength.
(AL/L)K
Read the load value P at the breaking point, calculate the tensile strength according to formula (B3), and take three significant figures. 10000P
Wherein: a-
Tensile strength, MPa;
P. Load value corresponding to the breaking point, cN.
B5.4 Elongation at break e
Read the maximum elongation at the breaking point △L·Calculate the elongation at break according to formula (B4), accurate to one decimal place. AL
Wherein-
Elongation at break:
×100%
Elongation at the breaking point, mm.
Results and data processing
JB/T 785295
The arithmetic mean of the tensile strength, initial tensile modulus and elongation at break of 30 fiber monofilaments are taken as the test results of the sample. B6.1
Calculate the standard deviation and dispersion coefficient according to formula (B5) and formula (B6). s
In the formula: S standard deviation:
C, dispersion coefficient;
X.—Test result of each fiber monofilament;
also—Arithmetic mean of mechanical quantity:
Month—Number of measured monofilaments.
×100%
.....(B6)
B6.3 The dispersion coefficients of tensile strength, initial tensile modulus and elongation at break should be less than 30%, 30% and 25% respectively, otherwise re-sampling and re-testing should be carried out.
Additional Notes:
This standard was proposed and managed by the Hefei General Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by Hunan University.
The main drafters of this standard are Xu Zhongyu, Liu Hongbo and Yang Cuizhi.
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