HG/T 2365-1992 Determination of moisture content of poly(alkylene terephthalate) pellets
Some standard content:
Chemical Industry Standard of the People's Republic of China
HG/T2365-92
ISO 6188-86
Polyalkylene terephthalate granules
Determination of water content
Published on October 7, 1992
Ministry of Chemical Industry of the People's Republic of China
The standard was implemented on May 1, 1993
Chemical Industry Standard of the People's Republic of China
Polyalkylene terephthalate granules
Determination of water content
HG/T2365-92
ISO6188-86
This standard is equivalent to the international standard ISO6188-86 "Plastics-Determination of water content of polyalkylene terephthalate granules". 1 Subject content and scope of application
This standard specifies the method for determining the moisture content of polyethylene terephthalate and polybutylene terephthalate pellets. This standard is applicable to the determination of moisture content in the range of 0.002% to 0.05% (m/m). This standard is not applicable to polyethylene (butylene) terephthalate samples containing volatile compounds other than water in such quantities that they have a significant impact on the vapor pressure at room temperature. The moisture content is very important for material processing. To prevent material degradation during processing, the moisture content should be less than a few parts per million. In dry polyethylene terephthalate pellets, the error caused by the presence of a small amount of acetaldehyde can be allowed. The presence of a large amount of volatile compounds should be checked regularly by some method, such as gas chromatography. This check is particularly necessary for new or new grades of materials. 2 Principle
Place the sample in a closed space under high vacuum and heat it to 200±5°C to ensure that the moisture is completely evaporated, and measure the pressure increase caused. The pressure increase is proportional to the water content. The reference material is a hydrate (such as sodium molybdate dihydrate) with a known water content that loses water under the test conditions. Determine the correction factor and calculate its water content. 3 Reagents
3.1 Sodium molybdate dihydrate (Na,MoOg.2H,O). Note: Other hydrates that lose crystal water under the test conditions, such as barium chloride dihydrate (BaCl,2H,O), can also be used. Instruments
General laboratory instruments
4.1 Measuring instrument
The following moisture measuring instrument is recommended, as shown in the schematic diagram. It is a vacuum-tightly connected glass system, and the joint is preferably spherical. Spherical bottles A and B have a volume of 0.5±0.05L and at least 1L, respectively. Two spherical bottles are connected to tube C: one end of tube C is connected to high vacuum pump D, and the other end is connected to the sample tube joint equipped with piston E. Tube C is connected to a vacuum pump equipped with piston F, and is equipped with piston G to separate the spherical bottles. On both sides of piston G, tube C is connected to U-tube oil pressure gauge L through injection head H and check valve K. The branch pipe length of the oil pressure gauge is at least 350mm, and the sample tube M should be made of heat-resistant glass. The volume difference of each group of sample tubes should not exceed 5ml. Note: ① If the repeatability described in 6.2.2 can be achieved, it is allowed to use instruments of different designs. ② It is best to use silicone oil as the filling liquid of the oil pressure gauge. The Ministry of Chemical Industry of the People's Republic of China approved the standard on October 7, 1992. The standard is pre-changed on the net mm.b2808a:ccn. Various standards and industry resources are free for free download. 1993-05-01 implementation
HG/T2365-92
Figure Water content tester
A-spherical bottle 0.5±0.05L; B-spherical bottle not less than 1LC-connecting pipe; D-high vacuum pump; E, F, G-piston; H-spray Nozzle; K-check valve; L-oil pressure gauge: M-sample tube 4.2 Heating devicebZxz.net
Use an electric furnace or any other suitable device to heat the sample tube to 200±5. For ease of operation, the heating device should be easy to load and unload.
5 Sample
Quickly put a representative sample of the test material into a dry container and seal it immediately to minimize moisture absorption from the atmosphere. Note: The container should be dried in an oven in advance and then placed in a desiccator containing a suitable desiccant, such as blue silica gel, to cool. Standard fee report network mm, bteosa:cen various standard industry information reports free download 6 operating steps
HG/T2365-92
6.1. Leak detection
The instrument leak detection method is as follows: Install the dry sample tube on the instrument. This tube does not need to be heated during leak detection. Rotate piston E to make the sample tube and tube C communicate, and rotate piston G to make spherical bottles A and B communicate. Evacuate the system to a pressure less than 100Pa (100Pa=1mbar~0.7mmHg), close pistons F and G. After 1h, check whether the pressure is still less than 100Pa, and whether the pressure difference indicated by the oil pressure gauge is less than 2mm oil column. If the above requirements are not met, check the leakage point and re-test. To ensure the airtightness during measurement, leak detection should be carried out at any time as needed. Note: When changing the oil of the oil pressure gauge, in order to exclude the gas in the new oil, the instrument must be evacuated for several hours. 6.2 Determination
6.2.1 Quickly pour the sample with a volume equivalent to 12~18g into the dry sample tube, and install the sample tube on the instrument. Rotate piston E to connect the sample tube with tube C, and rotate piston G to connect spherical bottles A and B. Evacuate the system to a pressure less than 100Pa, and close pistons F and G. Put the heating device preheated to 200±5℃ on the outside of the sample tube, and heat the sample tube at this temperature for 50min. Or heat it until the pressure difference of the oil pressure gauge changes by no more than 1mm oil column within 5min. Note: ① To minimize the error caused by moisture absorption from the atmosphere, first estimate the sample by volume, and then weigh it after heating. ② When the sample is powder, slowly evacuate the sample. It is recommended to cover the sample with a thin layer of glass wool. The glass wool is pre-dried and placed in a desiccator containing an appropriate desiccant (such as blue silica gel) for cooling. ③ The unknown sample may have a high water content. Therefore, within the initial 10 minutes of the test, the oil pressure gauge should be observed frequently. If the pressure rises too high, open piston G and take a smaller sample to repeat the test. After 50 minutes, or when the oil pressure difference remains unchanged, read the pressure difference accurately to the millimeter, stop heating the sample tube, open piston G and rotate piston E to eliminate the vacuum in the sample tube. Cool the sample tube and weigh it (accurate to 0.01g). 6.2.2 Perform two measurements on each sample. If the result difference is greater than 0.005% (m/m), check for leaks (see 6.1) and repeat the measurement twice.
6.3 Calibration
6.3.1 Weigh at least five samples of sodium molybdate dihydrate (3.1) with a mass ranging from 30 to 40 mg and place them in clean and dry sample tubes.
Each sodium molybdate dihydrate sample is weighed according to the steps specified in 6.2.1. The operation can be carried out in one step, and the heating time can be shortened from 50min to 15min.
6.3.2 According to formula (1), calculate the corresponding correction coefficient fm.w
of the amount of water (g) required to produce 1mm oil pressure difference, where: m-sodium molybdate dihydrate sample mass, g;
water content of sodium molybdate dihydrate, g/g
Ap pressure difference indicated by oil pressure gauge, mm oil column
If hydrates other than sodium molybdate dihydrate are used for correction, the mass and water content of the sample need to be coordinated with each other. Take the average of each test value as the correction coefficient calculation, and the value with a difference of more than 5% from the average value shall be eliminated. Note: ① When using new sodium molybdate dihydrate, the moisture content should be determined by the mass difference after drying at 200 °C for 1 hour. ② Do not use water for correction because the required mass is too small to be accurately weighed. (1)
Calculation of test results
HG/T2365-92
The moisture content is calculated according to formula (2) and expressed as mass percentage: f.Ap
In the formula ：f——Correction coefficient determined according to 6.3;Ap
Pressure difference indicated by oil pressure gauge, mm oil column;
Test report
Mass of test material, g.
The test report shall include the following contents:a.
Indicate the adoption of this professional standard;
Complete sample identification;
Single test result and average value of two determinations, accurate to 0.001% (m/m); Test personnel;
Test date.
Additional remarks:
This standard is proposed by the Science and Technology Department of the Ministry of Chemical Industry of the People's Republic of China and is under the jurisdiction of the Chemical Method Branch of the National Technical Committee for Plastic Standardization. This standard was drafted by Fujian Provincial Central Inspection Institute. The main drafters of this standard are Lin Guanlou and Lin Guzhao. (2)
From the date of implementation of this standard, the original national standard GB7140-86 "Determination of water content in polyethylene terephthalate granules" will be invalid.
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Chemical Industry Standard
Polyalkylene terephthalate granules
Determination of water content
HG/T2365-92
Editor Chemical Industry Standard Editorial Department
(Standardization Research Institute of Ministry of Chemical Industry)
Postal Code: 100013
Printing Chemical Industry Standardization Research Institute
Copyright is exclusive and may not be reproduced
Format 880×12301/16 Printing Sheet Word Count 8000 First Edition in May 1993
First Printing in May 1993
Print Count 1-500
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