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A Characterization Method of Entanglement Degree of High Molecular Weight Polyethylene

A high-molecular-weight, polyethylene technology, applied in measuring devices, analytical materials, thermal analysis of materials, etc., can solve the problems of difficult or impossible to judge polyethylene, and difficult to test the degree of entanglement of products, achieving high reliability and convenient operation. , the effect of data

Active Publication Date: 2021-02-12
CHINA PETROCHEMICAL TECH CO LTD +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The data obtained by high-temperature rheology is the entanglement of molecular chains when polyethylene is melted. This data is more effective in characterizing the entanglement of molecular chains during material processing, but it is difficult to test the degree of entanglement of products.
The data obtained by high-temperature gel chromatography are only the size and distribution of molecular weight. For high-molecular-weight polyethylene, especially ultra-high-molecular-weight polyethylene, the influence of molecular structure on the degree of molecular chain entanglement of its raw materials and products is only one aspect. Samples The thermal history of polyethylene will also have a great impact on the degree of entanglement, and the superposition of the effects of different thermal histories and molecular structure makes it extremely difficult to judge the degree of entanglement of polyethylene molecular chains
However, the method of judging the degree of molecular chain entanglement of polyethylene density test is only applicable to polyethylene homopolymer products, and cannot be judged for raw materials and products containing short chain branches.

Method used

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  • A Characterization Method of Entanglement Degree of High Molecular Weight Polyethylene
  • A Characterization Method of Entanglement Degree of High Molecular Weight Polyethylene
  • A Characterization Method of Entanglement Degree of High Molecular Weight Polyethylene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Take the ultra-high molecular weight polyethylene raw material with a viscosity average molecular weight of 3 million, and use 120# gasoline as the diluent to obtain the raw material by polymerization in a tank reactor at 80°C. The raw material and decahydronaphthalene solvent were dissolved at 150° C. for 3 hours with a solid content of 1%, and the antioxidant content was 2‰. The resulting solution was introduced into 5°C cooling water at high temperature and cooled for 10 minutes. The obtained solid was placed in n-hexane and extracted for 5 minutes, then taken out and placed in a drying oven for drying at room temperature.

[0037] Weigh 5.0 mg of the dried polyethylene sample and test it in DSC. After heating up to 110°C at a rate of 10°C / min and staying for 10 minutes, the temperature was lowered to 30°C at a rate of 10°C / min, and then raised to 160°C at a rate of 10°C / min. The melting peak after the temperature rise was integrated to obtain a melting enthalpy of...

Embodiment 2

[0041] The ultra-high molecular weight polyethylene raw material with a viscosity average molecular weight of 3 million is taken, and the raw material is obtained by polymerization in a tubular reactor at 20° C. using n-hexane as a diluent. The raw material and decahydronaphthalene solvent were dissolved at 150° C. for 3 hours with a solid content of 1%, and the antioxidant content was 2‰. The resulting solution was introduced into 35°C cooling water at high temperature and cooled for 10 minutes. The obtained solid was placed in n-hexane and extracted for 5 minutes, then taken out and placed in a drying oven for drying at room temperature.

[0042] Weigh 5.0 mg of the dried polyethylene sample and test it in DSC. After heating up to 110°C at a rate of 10°C / min and staying for 10 minutes, the temperature was lowered to 30°C at a rate of 10°C / min, and then raised to 160°C at a rate of 10°C / min. The melting peak after the temperature rise was integrated to obtain a melting enth...

Embodiment 3

[0046] Take an ultra-high molecular weight polyethylene raw material with a viscosity-average molecular weight of 2 million, and place the raw material on a hot-press molding machine for hot-press molding. The hot-press temperature is 220° C., the hot-press time is 4 hours, and the hot-press pressure is 10 MPa. The ultra-high molecular weight polyethylene raw material and trichlorobenzene solvent were dissolved at 150° C. for 4 hours with a solid content of 2%, and the antioxidant content was 4‰. The resulting solution was transferred to 5°C cooling water at high temperature and cooled for 10 minutes. The obtained solid was placed in n-hexane and extracted for 5 minutes, then taken out and placed in a drying oven for drying at room temperature.

[0047] Weigh 5.0 mg of the dried polyethylene sample and test it in DSC. After heating up to 110°C at a rate of 10°C / min and staying for 10 minutes, the temperature was lowered to 30°C at a rate of 10°C / min, and then raised to 160°C ...

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Abstract

The invention relates to a method for characterizing the degree of entanglement of high-molecular-weight polyethylene, which comprises the following steps: (1) placing the high-molecular-weight polyethylene to be tested and an antioxidant in a solvent, and dissolving them at high temperature to obtain a mixed solution; (2) ) adding the mixed solution to a low-temperature medium that does not react with polyethylene for rapid cooling, and then drying the precipitated high polymer to obtain a low-entangled standard sample; (3) adding the standard sample and the high molecular weight polyethylene to be tested Place them in a differential scanning calorimeter and perform the same measurement to obtain the melting enthalpy value H of the standard sample 1 And the melting enthalpy value H of the sample to be tested 2 ; (4) will (H 1 -H 2 ) / H 1 As the degree of entanglement of high molecular weight polyethylene to be tested. Compared with the prior art, the present invention mainly adopts the differential scanning calorimeter to carry out the experiment, and solves the difficulty in characterizing the degree of molecular chain entanglement of the current high molecular weight polyethylene raw materials and products, especially ultra-high molecular weight polyethylene raw materials and products. , the proof method is convenient and simple to operate, and the data are representative.

Description

technical field [0001] The invention relates to the technical field of polymer material characterization, in particular to a characterization method for the entanglement degree of high molecular weight polyethylene. Background technique [0002] With the rapid development of science and technology, the application range of polyethylene raw materials is becoming wider and wider, the output is increasing year by year, and the performance of polyethylene is also continuously improving. In many fields of high-performance materials, the proportion of polyethylene products is also increasing, such as body armor, high-speed rail bridge brackets, wear-resistant pipes, aerospace materials, elevator sliders and so on. The performance of these polyethylene products is closely related to the entanglement of molecular chains of polyethylene, especially for high molecular weight polyethylene products, the degree of entanglement of molecular chains is often the key to the difference in per...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N25/48
CPCG01N25/4833
Inventor 叶纯麟李建龙肖明威布志捷郭宁宁晓燕卢伟京刘方涛阳永荣徐浩骆广海夏磊赵世成
Owner CHINA PETROCHEMICAL TECH CO LTD