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Method for measuring content of short-chain branches in polyethylene copolymer

A technology of polyethylene copolymer and measurement method, which is applied in the direction of measuring devices, flow characteristics, instruments, etc., can solve the problems of limitations, failure to reflect the overall structure of samples, and high requirements for test sample preparation conditions, and achieve the effect of low requirements and easy operation

Active Publication Date: 2014-08-06
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the above two methods require very few samples. If the sample uniformity is poor, the single measurement result cannot reflect the overall structure of the sample.
At the same time, the instruments used are sensitive to environmental factors such as temperature, humidity, and even vibration, and require high preparation conditions for test samples, so they are limited in practical applications

Method used

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  • Method for measuring content of short-chain branches in polyethylene copolymer
  • Method for measuring content of short-chain branches in polyethylene copolymer
  • Method for measuring content of short-chain branches in polyethylene copolymer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] 1.1 Determination of the content of short chain branches in polyethylene copolymer standard samples

[0041]The standard sample used is a randomly selected polyethylene copolymer, and the infrared spectroscopic method is used according to the literature "infrared spectroscopic practical characterization of PE microstructure" [Xie Kan, Chen Dongmei, Cai Xia, etc. Synthetic Resin and Plastics, 2005, 22 (1) : 48-52], the method measures each ethylene and different monomer (butene, hexene) copolymer short chain branch content value, and each standard sample prepares 5 samples, and the result of testing respectively is averaged and set Set as the true value of the short chain branch content of the standard sample. The specific test steps are:

[0042] 1) Press the pellet or powder sample into a 0.4mm thick sheet at 170°C in a metal mold lined with aluminum foil;

[0043] 2) Use the MAGNA-IR 760 infrared spectrometer of Nigoli Company of the United States to test the sample...

Embodiment 2

[0078] Viscous flow activation energy E of polyethylene copolymer at extremely low frequency η The assay method is with embodiment 1. According to E η Find the corresponding short chain branch content from the working curve, or put E η The value is to be entered into the regression equation to calculate the short chain branch content of the sample.

[0079] 2.1 Determination of short-chain branch content in ethylene-butylene copolymer

[0080] sample

15#

16#

17#

E. η / (KJ·mol -1 )

15.8

19.2

21.5

D B

5.01

9.39

13.50

D. B (IR)

5.1

9.3

13.6

absolute error

-0.09

0.09

-0.1

Relative error

1.76％

0.97％

0.74％

[0081] 2.2 Determination of short-chain branched chain content in ethylhexyl copolymer

[0082] sample

Embodiment 3

[0084] Viscous flow activation energy E of polyethylene copolymer at extremely low frequency η The assay method is with embodiment 1. The assay method of polyethylene copolymer short chain branch content is the same as embodiment 2. Prepare different samples for the same sample to test the reliability of the method.

[0085] 3.1 Determination of short-chain branched content in ethylene-butylene copolymer

[0086] sample

16#-1

16#-2

16#-3

16#-4

16#-5

E. η / (KJ·mol -1 )

19.1

19.2

19.3

19.0

19.1

D B

9.22

9.39

9.54

9.07

9.22

absolute error

-0.17

0

0.15

-0.32

-0.17

[0087] Average 9.29

[0088] Mean absolute error 9.29-9.39=-0.1

[0089] Relative error 0.1 / 9.39*100%=1.1%

[0090] 3.2 Determination of short-chain branched chain content in ethylhexyl copolymer

[0091] sample

19#-1

19#-2

19#-3

19#-4

19#-5

[0092] ...

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Abstract

The invention relates to a method for measuring a content of short-chain branches in a polyethylene copolymer. The method is used for measuring the content of short-chain branches in a copolymer of ethylene and different monomers (butane / hexene). The method comprises the following steps: measuring the change of complex viscosity of the copolymer of ethylene and different monomers (butane / hexene) following the change of temperature under ultralow frequency by using a dynamic rheometer, thereby acquiring the viscosity activation energy E Eta of a polyethylene copolymer sample, and then calculating the content of short-chain branches by utilizing a regression formula DB=a*E Eta b, wherein a and b in the regression formula are constants and the values of a and b can be solved by utilizing the viscosity activation energy of a standard sample and the content of short-chain branches. The method provided by the invention is easily operated and is high in practicability.

Description

technical field [0001] The invention relates to an analysis method for polyolefins, in particular to a method for measuring short-chain branch content in copolymers of ethylene and different monomers (butene, hexene). Background technique [0002] In recent years, in the development of high-performance and differentiated polyethylene resins, major companies in the world have increasingly adopted the technical route of polymerizing ethylene and other comonomers to obtain polyethylene copolymers with excellent performance. The chemical properties, crystallization properties, rheological properties and processing properties of polyethylene copolymers are becoming more and more diverse, which requires analytical research on their chemical structures. [0003] Through the determination of the content of short-chain branches in polyethylene copolymers, information such as the content of comonomers and the degree of branching in polyethylene copolymers can be obtained, so as to pro...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N11/00
Inventor 李朋朋谢昕梁天珍赵家琳王美玲郭义许惠芳高杜鹃樊洁魏福庆金鼎铭刘永军
Owner PETROCHINA CO LTD
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