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Characterization method for polymer molecular weight

A polymer and molecular weight technology, applied in the field of polymers, can solve the problems of increased test cost, chromatographic column replacement, and high cost, and achieve the effects of less sample amount and solvent amount, accurate test results, and low characterization cost.

Active Publication Date: 2016-12-07
CHANGZHOU INST OF ENERGY STORAGE MATERIALS &DEVICES
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

However, there are three shortcomings in the existing GPC technology to characterize the molecular weight of polymers: (1) The test of the average molecular weight of each sample requires 60 ml of highly toxic trichlorobenzene, the sample size is about 20 mg, and the purification and recovery of trichlorobenzene is difficult , so the cost is high; (2) the use of a large amount of trichlorobenzene is more serious to the pollution of the environment, especially the water source; (3) the chromatographic column needs to be replaced frequently, further increasing the test cost

Method used

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  • Characterization method for polymer molecular weight
  • Characterization method for polymer molecular weight

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Embodiment 1

[0040] The test instrument is a Bruker Ascend series 400MHZ liquid nuclear magnetic resonance spectrometer, the probe is a BBFO broadband high-resolution liquid probe, and the Z gradient field is 5.35G / mm.

[0041] 1) Instrument calibration

[0042] The instrument was calibrated for temperature over the 300-380K range using 80% ethylene glycol in deuterated DMSO standard.

[0043] Use containing GdCl 3 99% of D 2 O / 1%H 2 The self-diffusion coefficient of water was repeatedly tested with the O standard sample until the diffusion coefficient of water at 298K was 1.872e-9, so as to realize the correction of the gradient.

[0044] 2) Determination of linear polyethylene molecular weight and molecular distribution

[0045] a) Acquisition of standard curve

[0046] A range of linear polyethylenes of known molecular weight and distribution are selected from Table 1. Weigh 3 mg of sample and dissolve it in a glass tube with a caliber of 10 mm, add 6 mL of deuterated tetrachloroe...

Embodiment 2

[0056] The pulse sequence used by 1D DOSY is still ledbpg2s1d, the diffusion time parameter (D20) is adjusted to 100ms, and the gradient pulse duration varies with the molecular weight between 300-1800us. Pulse gradient strengths were set to 1% and 98%, respectively. A two-dimensional DOSY experiment was performed on the sample PE4 to obtain its 2D DOSY spectrum at 110°C, and then obtain the diffusion coefficient. 2D DOSY spectrum such as Figure 6 Shown, where, F1 dimension is the sample 1 H NMR spectrum, F2 dimension is the diffusion axis, as can be seen from the figure, where 1.40ppm is polyethylene 1 H NMR signal peak, 6.0ppm is the signal of deuterated reagent. The two signals on the two-dimensional plane correspond to the diffusion signals of the polyethylene sample and the solvent under the experimental conditions, and the diffusion rates are 1.332*10 -9 m 2 / s and 5.32*10 -9 m 2 / s, with figure 2 The DOSY spectra of PE4 shown are basically the same, and the di...

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Abstract

The invention provides a characterization method for polymer molecular weight. The method comprises the following steps: performing a two-dimensional molecular diffusion experiment in a nuclear magnetic resonance technology (namely, two-dimensional diffusion-ordered spectroscopy (2D DOSY)) on a polymer solution with a known molecular weight to obtain a diffusion coefficient, and establishing a standard curve of the polymer molecular weight and the diffusion coefficient; performing a two-dimensional molecular diffusion experiment on a to-be-measured polymer solution with an unknown molecular weight to obtain a diffusion coefficient, and calculating the molecular weight of a to-be-measured polymer and distribution thereof according to the standard curve of the molecular weight of the type of polymer and the diffusion coefficient, wherein the concentration of the to-be-measured polymer solution is controlled at 0.2-1.5mg / mL and the experimental temperature is controlled at 90-150 DEG C according to the molecular size. The method is easy to operate, the needed sample size and solvent amount are very small, the characterization cost is low, and a test result is accurate; moreover, two or more different types of polymers with approximate molecular weights in polymers can be distinguished while the polymer molecular weight and the molecular weight distribution are characterized.

Description

technical field [0001] The invention relates to the field of macromolecules, in particular to a method for characterizing the molecular weight of polymers. Background technique [0002] The molecular weight and distribution of polymers have an important impact on the properties of polymer materials, so they become necessary characterization indicators in the process of polymer science research. However, some non-polar high polymers containing only hydrocarbon elements do not have functional groups and are insoluble in common organic solvents (such as tetrahydrofuran) at room temperature. The molecular weight parameters of such polymers can only be obtained by means of high temperature GPC in solvents such as benzene. [0003] The principle of high-temperature GPC is to use high-temperature trichlorobenzene to dissolve the polymer and wash it to make it walk in the chromatographic column, and then determine the number-average and weight-average molecular weight by the reside...

Claims

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Application Information

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IPC IPC(8): G01N24/08G01N13/00
CPCG01N13/00G01N24/08G01N2013/003
Inventor 龙映云李百祥曾宝华
Owner CHANGZHOU INST OF ENERGY STORAGE MATERIALS &DEVICES
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