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On-line detection device and detection method of PPTA molecular weight in aramid solutions

A detection device and molecular weight technology, which is applied in the field of organic solvents, can solve problems affecting the continuous production of aramid fiber, and achieve the effects of continuous and stable production, convenient operation, and simple preparation structure

Active Publication Date: 2018-11-23
SINOPEC YIZHENG CHEM FIBER +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Purpose of the invention: the purpose of the present invention is to address the deficiencies in the prior art, to provide an on-line detection device and detection method for the molecular weight of PPTA in aramid fiber solution, and to solve the problem that GPC and intrinsic viscosity tests need to be operated offline, thereby affecting the continuous production of aramid fibers. problem, the molecular weight of PPTA solute can be detected online during the preparation of aramid fiber, so as to control the quality of aramid fiber

Method used

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  • On-line detection device and detection method of PPTA molecular weight in aramid solutions
  • On-line detection device and detection method of PPTA molecular weight in aramid solutions
  • On-line detection device and detection method of PPTA molecular weight in aramid solutions

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Experimental program
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Effect test

Embodiment 1

[0035] First with the NDJ-1D type rotor viscometer, its rotor diameter is 7.56mm, the rotor speed is 20rpm, and the diameter of the cylinder hopper is 19.14mm, the apparent viscosity ( PPTA sample is dissolved into the solution of 18% mass percent concentration with 100% sulfuric acid), obtains regression relation:

[0036] [η]=-n 1 ×10 -5 n a +n 2 (3)

[0037] where n 1 =2.12~10.86, n 2 =6.23~15.14; the unit of [η] is dL / g, η a The unit is mPa·s.

[0038] The pump supply volume of the metering pump 1 in the device is 1.0cc / r, and the rotating speed is 26.8rpm. The diameter D1 of the annular pipeline formed by the first round pipe 2 and the second round pipe 3 is 50cm, and the diameter D2 of the pipeline is 1.2cm, the diameter of the throttling wool tube is 0.5mm, the aspect ratio is 120, and the constant temperature environment is 80°C.

[0039] The actual spinning solution on the aramid spinning production line is a solution obtained by dissolving 18% PPTA in sulfu...

Embodiment 2

[0042] Embodiment 2: Due to the need for continuous large-scale production of aramid fibers, it is difficult to adjust the spinning equipment and process after it is stabilized. Therefore, the process conditions in this embodiment are the same as those in Embodiment 1. The only difference is that the product of the previous polymerization process optimization of the PPTA polymer powder used: in order to deduct the perishable factor of terephthaloyl chloride, when performing condensation polymerization with p-phenylenediamine, an excess of 0.3% p-phenylene Diformyl chloride. The product is spun under the same conditions as in Example 1, and the calculation results of the computer program show that the apparent shear viscosity of the aramid spinning solution is 19500 ± 849mPa·s, and the intrinsic viscosity of PPTA is 6.652 ± 0.051, (viscosity Average) molecular weight is 44313 ± 321.

[0043] Sampling the spinning solution, precipitating PPTA with water, washing and drying, dis...

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Abstract

The invention discloses an on-line detection device and detection method of PPTA molecular weight in aramid solutions. A horizontally-arranged flowing path is formed by sequentially connecting a metering pump, a first circular pipe, a throttling capillary pipe and a second circular pipe; a metering pump inlet and a second circular pipe outlet positioned at the two ends of the flowing path are respectively laterally connected with an aramid spinning liquid conveying pipeline; one differential pressure sensor is respectively connected with the first circular pipe and the second circular pipe; the other differential pressure sensor is connected with the throttling capillary pipe. The apparent viscosity of a series of PPTA (poly-p-phenylene terephthalamide) with known characteristic viscosityunder certain temperatures and concentrations is determined, and a regression equation is built through numerical value fitting; after parameters are measured and calculated by the detection device toobtain the apparent viscosity, the characteristic viscosity of the PPTA in the solution can be deduced by contrast of the regression equation, and then the viscosity average molecular weight of the PPTA can be calculated. According to the on-line detection device and detection method disclosed by the invention, real-time monitoring of the PPTA molecular weight on an aramid production line can berealized, continuous and stable production is facilitated, and the required device has the advantages of simple structure and convenience in operation; moreover, the stable requirement on the properties of the product can be ensured because of measurement accuracy.

Description

technical field [0001] The invention relates to an organic solvent, in particular to a method for recovering the organic solvent. Background technique [0002] Aramid fibers have the characteristics of high strength, high modulus, high temperature resistance, acid and alkali resistance, and corrosion resistance. They are widely used in national defense, aerospace industry, ships, cords, communication cables, and reinforced composite materials. They are ideal Military and civilian dual-use raw materials. Among the three high-performance fibers (aramid, high-strength polyethylene, carbon fiber), aramid has the fastest development speed, the largest output and demand, and the annual demand growth rate is over 10%. [0003] Aramid fiber is prepared from concentrated sulfuric acid solution of PPTA through liquid crystal spinning technology. There are many factors affecting the performance of aramid fibers, among which the properties of PPTA itself, especially its molecular weig...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N11/14
CPCG01N11/14
Inventor 杨勇杨胜林王芳梁园王伟严岩
Owner SINOPEC YIZHENG CHEM FIBER