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Detection method for molecular weight of polyethylene

A measurement method, polyethylene technology, applied in the direction of measuring devices, analysis materials, flow characteristics, etc., can solve problems such as limitations

Active Publication Date: 2013-07-31
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The relationship between viscosity and molecular weight of different types of polyethylene is different, which limits the application of rheological means to measure the molecular weight of polyethylene

Method used

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  • Detection method for molecular weight of polyethylene
  • Detection method for molecular weight of polyethylene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] This method is applicable to the dynamic rheometer of various models, and the used instrument of the present invention is:

[0043] (1) AR-G2 dynamic rheological analyzer produced by American TA company

[0044] Frequency range: 7.54×10 -7 ~628.3rad / s, temperature range: -150~400℃

[0045] (2) Shanghai Puda Hydraulic Machinery Manufacturing Co., Ltd. produces XLB-0.25D / Q flat vulcanizing machine

[0046] Pressure: 0~16MPa, Temperature: 0~300℃

[0047] 1.1 Test sample preparation

[0048] In a flat vulcanizing machine, use a mold at 180°C to press the granular polyethylene sample 1# into a disc with a diameter of 25 mm and a thickness of 2 mm, which is uniform, free of bubbles, and has a clean and flat surface.

[0049] 1.2 Test steps

[0050] (1) Turn on the compressed air and adjust the inlet pressure of the rheometer to 30psi;

[0051] (2) Open the safety lock of the rheometer;

[0052] (3) AR-G2 rheometer main engine is turned on, and after the instrument pass...

Embodiment 2

[0066] According to the method of Example 1, the rheological test and calculation were carried out on the powdered polyethylene sample 2#, and the sample was determined to belong to the polyethylene H category according to the RSI. The results are shown in Table 2. The GPC test method used to verify the reliability of the method of the present invention is the same as in Example 1, and the results are shown in Table 2.

Embodiment 3

[0068] According to the method of Example 1, the granular polyethylene sample 3# was subjected to rheological tests and calculations. According to the RSI, it was determined that the sample belonged to the polyethylene L category. The results are shown in Table 2. The GPC test method used to verify the reliability of the method of the present invention is the same as in Example 1, and the test results are shown in Table 2.

[0069] Sample test and calculation result in the embodiment of table 2

[0070]

[0071] As can be seen from Table 2, the same polyethylene sample is very close to the molecular weight measured by the method of the present invention and GPC, indicating that the method of the present invention can be effectively used to measure the molecular weight of polyethylene.

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Abstract

The invention relates to a detection method for molecular weight of polyethylene. The method comprises: (1) adopting a dynamic rheometer to carry out frequency scanning measurement for a polyethylene sample in a linear viscoelastic region; (2) calculating a relaxation spectrum distribution width of the polyethylene sample according to the frequency scanning result, and determining the type of thepolyethylene sample according to the relaxation spectrum distribution width; (3) calculating zero shear viscosity of the polyethylene sample according to the frequency scanning result; (4) substituting the zero shear viscosity of the polyethylene sample into a regression formula of the type of the polyethylene sample to calculate the molecular weight of the sample, wherein the regression formula is as the follow: eta0= K(MW)<alpha>. According to the present invention, no solvent pollution is generated when the method is adopted to carry out testing; the method is easy to operate, and providesgood adaptability for the whole structure of the polyethylene sample; with considering the different dependency relationships between the zero shear viscosity of the polyethylene with the different types and the molecular weight, the method has wide applicability.

Description

technical field [0001] The invention relates to a method for determining molecular weight of polyethylene, in particular to a method for determining molecular weight of polyethylene by means of rheology. Background technique [0002] At present, polyethylene resin is the synthetic resin variety with the largest output and consumption, and the annual domestic consumption of polyethylene has exceeded 10 million tons. With the continuous production of new polyethylene plants at home and abroad, the competition in the field of polyethylene resin is becoming increasingly fierce. In order to occupy a favorable position in the fierce market competition, it is necessary to develop high-performance polyethylene resin products and provide technical services that meet user needs. To achieve these two goals, it is necessary to have a clear understanding of various factors that affect the performance of polyethylene resin products, especially the molecular chain structure, and the molec...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N11/00
Inventor 李朋朋王美玲谢昕梁天珍姚自余杨芳贾慧青樊洁郭义巨娟侠金鼎铭刘永军
Owner PETROCHINA CO LTD
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