阅读说明：本技术 一种再生abs塑料中各单体单元组成含量的检测方法 (Method for detecting composition content of each monomer unit in regenerated ABS (acrylonitrile butadiene styrene) plastic ) 是由 熊维 朱宽 于 2021-01-06 设计创作，主要内容包括：本发明公开了一种再生ABS塑料中各单元单体组成含量的检测方法,包括以下步骤：(1)准备样品；(2)对样品进行拉曼光谱定性分析；(3)对样品进行热失重分析；(4)提取样品中的ABS聚合物；(5)对ABS聚合物进行核磁共振氢谱测试；(6)根据三种单体的各自官能团的出峰位置不同,由各自峰面积之比计算百分含量。本发明先采用拉曼光谱定性分析得出再生ABS塑料的成分组成,由热失重法分析进一步确定,然后通过提取ABS聚合物以去除再生料中的炭黑和其他无机物,以保证所要测量单体含量的准确性,最后采用核磁共振氢谱测量ABS聚合物,通过谱图中各单体对应的峰面积得出对应的含量,本发明具备样品处理简便、测量的精确性和准确性较好等优点。(The invention discloses a method for detecting the composition content of each unit monomer in regenerated ABS plastic, which comprises the following steps: (1) preparing a sample; (2) performing Raman spectrum qualitative analysis on the sample; (3) carrying out thermogravimetric analysis on the sample; (4) extracting the ABS polymer in the sample; (5) performing nuclear magnetic resonance hydrogen spectrum test on the ABS polymer; (6) the percentage content is calculated from the ratio of the respective peak areas according to the difference of the peak positions of the respective functional groups of the three monomers. The method comprises the steps of firstly obtaining the component composition of the regenerated ABS plastic by adopting Raman spectrum qualitative analysis, further determining by thermogravimetric analysis, then removing carbon black and other inorganic matters in the regenerated material by extracting the ABS polymer to ensure the accuracy of the content of the monomer to be measured, and finally measuring the ABS polymer by adopting nuclear magnetic resonance hydrogen spectrum, and obtaining the corresponding content through the peak area corresponding to each monomer in the spectrogram.)

1. A method for detecting the composition content of each monomer unit in regenerated ABS plastic is characterized by comprising the following steps:

(1) preparing a sample;

(2) performing Raman spectrum qualitative analysis on the sample;

(3) carrying out thermogravimetric analysis on the sample;

(4) extracting the ABS polymer in the sample;

(5) performing nuclear magnetic resonance hydrogen spectrum test on the ABS polymer;

(6) the percentage content is calculated from the ratio of the respective peak areas according to the difference of the peak positions of the respective functional groups of the three monomers.

2. The method for detecting the composition content of each monomer unit in the recycled ABS plastic according to claim 1, wherein the sample in the step (1) is a plurality of small blocks with the size of 5mm by 2 mm.

3. The method for detecting the composition content of each monomer unit in the recycled ABS plastic as claimed in claim 1, wherein the Raman spectroscopy qualitative analysis apparatus in step (2) is a confocal micro-Raman spectrometer, and the test conditions are as follows: laser wavelength 6328nm, a confocal hole of 400 μm, a slit of 100 μm, a grating of 650g/mm, a microscope lens of 50 times, a scanning range of 100-^-1Resolution 2cm^-1The scan time is 2 s.

4. The method for detecting the composition content of each monomer unit in the recycled ABS plastic according to claim 1, wherein the apparatus for thermal weight loss analysis in step (3) is Q500 from TA instruments of America, and the test conditions are as follows: the flow rate of nitrogen atmosphere is 50mL/min, the temperature range is 25-900 ℃, and the heating speed is 20 ℃/min.

5. The method for detecting the composition content of each monomer unit in the recycled ABS plastic according to claim 1, wherein the specific operation of extracting the ABS polymer in the step (4) is as follows: dissolving a sample by adopting a proper solvent, then filtering and centrifugally separating the solution, removing carbon black or other inorganic matters possibly existing in the solution to obtain an ABS polymer solution, and drying the ABS polymer solution to volatilize the solvent completely to obtain the ABS polymer.

6. The method for detecting the composition content of each monomer unit in the recycled ABS plastic as claimed in claim 5, wherein the solvent is one of chloroform or dichloromethane.

7. The method for detecting the composition content of each monomer unit in the recycled ABS plastic as claimed in claim 1, wherein the apparatus used for the nuclear magnetic resonance hydrogen spectrometry in step (5) is model DRX 400MHz of Bruker, under the test conditions of the magnetic field strength of 9.2T, the diameter of a nuclear magnetic tube of 5mm, deuterated chloroform as a solvent, TMS as an internal standard reagent for nuclear magnetic resonance, and the temperature is 120 ℃.

8. The method for detecting the composition content of each monomer unit in the recycled ABS plastic according to claim 7, wherein the nuclear magnetic resonance hydrogen spectrum test has a working frequency of 400.15MHz, a spectrum width of 8010.54Hz, a pulse width of 10 μ s, a pulse delay of 2s and 16 sampling times.

9. The method for detecting the composition content of each monomer unit in the recycled ABS plastic according to claim 7, wherein the samples for the NMR spectroscopy are as follows: and dissolving the ABS polymer in the deuterated chloroform solvent to prepare a solution with the concentration of 2.5-4% by mass fraction.

10. The method for detecting the composition content of each monomer unit in the recycled ABS plastic as claimed in claim 7, wherein the volume fraction of TMS is 0.05-0.2%.

Technical Field

The invention relates to a method for detecting organic monomer, in particular to a method for detecting the composition content of each monomer unit in regenerated ABS plastic.

Technical Field

The ABS plastic is a graft copolymer of three monomers of acrylonitrile (A), butadiene (B) and styrene (S), and the relative contents of the three monomers can be changed at will to prepare various resins. The ABS resin integrates the excellent properties of the three monomers, namely: gloss, electrical properties, moldability of styrene; heat resistance, rigidity, oil resistance of acrylonitrile; impact resistance of butadiene. The recycled ABS plastic is usually produced by recycling chemical products, corresponding products are manufactured through a certain processing means, the product requirements are different, and the attributes of the recycled ABS plastic are different, so that different products can be manufactured by using recycled materials. The performances of the ABS polymers are greatly different if the proportions of the three monomers are different, so that the component proportions of the three monomers of the ABS plastic must be accurately identified so as to judge whether the performances meet the requirements. However, the accuracy of some existing methods for detecting the recycled ABS plastics is not enough, and the efficiency is not high, so that the development of a method for conveniently, efficiently and accurately detecting the ABS plastics is particularly urgent.

Disclosure of Invention

The invention aims to provide a method for detecting the composition content of each monomer unit in regenerated ABS plastic, which is mainly used for carrying out quantitative analysis on the content of each monomer in an ABS polymer through H1-NMR (nuclear magnetic resonance hydrogen spectrum), and specifically, the percentage content is calculated according to the ratio of respective peak areas according to the difference of peak positions of respective functional groups of three monomers.

In order to realize the purpose, the adopted technical scheme is as follows: a method for detecting the composition content of each monomer unit in regenerated ABS plastic is characterized by comprising the following steps:

(1) preparing a sample;

(2) performing Raman spectrum qualitative analysis on the sample;

(3) carrying out thermogravimetric analysis on the sample;

(4) extracting the ABS polymer in the sample;

(5) performing nuclear magnetic resonance hydrogen spectrum test on the ABS polymer;

(6) the percentage content is calculated from the ratio of the respective peak areas according to the difference of the peak positions of the respective functional groups of the three monomers.

As a preferred scheme, the sample in the step (1) is a plurality of small blocks with the size of 5mm by 2 mm.

As a preferable scheme, the instrument for qualitative raman spectroscopy analysis in step (2) is a confocal micro-raman spectrometer, and the test conditions are as follows: the laser wavelength is 632.8nm, the confocal hole is 400 μm, the slit is 100 μm, the grating is 650g/mm, the microscope lens is 50 times, and the scanning range is 100-3200cm^-1Resolution 2cm^-1The scan time is 2 s.

As a preferred scheme, the apparatus for thermal weight loss analysis in step (3) is Q500 of TA instruments, usa, and the test conditions are as follows: the flow rate of nitrogen atmosphere is 50mL/min, the temperature range is 25-900 ℃, and the heating speed is 20 ℃/min.

As a preferred scheme, the specific operation of extracting the ABS polymer in the step (4) is: dissolving a sample by adopting a proper solvent, then filtering and centrifugally separating the solution, removing carbon black or other inorganic matters possibly existing in the solution to obtain an ABS polymer solution, and drying the ABS polymer solution to volatilize the solvent completely to obtain the ABS polymer.

As a preferred embodiment, the solvent is one of chloroform or dichloromethane.

In a preferred embodiment, the instrument used for the hydrogen spectrum test of nuclear magnetic resonance in step (5) is DRX 400MHz model of Bruker, under the test conditions of magnetic field strength of 9.2T, nuclear magnetic tube diameter of 5mm, deuterated chloroform as a solvent, TMS as an internal standard reagent of nuclear magnetic resonance, and temperature of 120 ℃.

In a preferred scheme, the operating frequency of the nuclear magnetic resonance hydrogen spectrum test is 400.15MHz, the spectrum width is 8010.54Hz, the pulse width is 10 mus, the pulse delay is 2s, and the sampling is carried out 16 times.

As a preferred embodiment, the sample for the nmr hydrogen spectrum test is: and dissolving the ABS polymer in the deuterated chloroform solvent to prepare a solution with the concentration of 2.5-4% by mass fraction.

In a preferred embodiment, the TMS has a volume fraction of 0.05-0.2%.

Has the advantages that:

the invention identifies the composition of the regenerated ABS plastic through Raman spectrum, verifies the analysis of Raman spectrogram through thermogravimetric analysis, further determines the components of the material, and then extracts ABS polymer in the sample through purification treatment to ensure accurate data of subsequent quantitative analysis. And finally, quantitatively analyzing the content of each monomer in the ABS polymer by adopting a nuclear magnetic resonance hydrogen spectrum so as to determine the proportion of each monomer. The data obtained by the detection method is accurate and reliable, and the method is simple and easy to operate.

Detailed Description

The invention will be further understood by reference to the following detailed description of preferred embodiments of the invention and the examples included therein. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. To the extent that a definition of a particular term disclosed in the prior art is inconsistent with any definition provided in the present disclosure, the definition of the term provided in the present disclosure controls.

As used herein, a feature that does not define a singular or plural form is also intended to include a plural form of the feature unless the context clearly indicates otherwise. It will be further understood that the term "prepared from …," as used herein, is synonymous with "comprising," including, "comprising," "having," "including," and/or "containing," when used in this specification means that the recited composition, step, method, article, or device is present, but does not preclude the presence or addition of one or more other compositions, steps, methods, articles, or devices. Furthermore, the use of "preferred," "preferably," "more preferred," etc., when describing embodiments of the present invention, is meant to refer to embodiments of the invention that may provide certain benefits, under certain circumstances. However, other embodiments may be preferred, under the same or other circumstances. In addition, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

In order to achieve the aim, the invention provides a method for detecting the composition content of each monomer unit in regenerated ABS plastic, which comprises the following steps:

(1) preparing a sample;

(2) performing Raman spectrum qualitative analysis on the sample;

(3) carrying out thermogravimetric analysis on the sample;

(4) extracting the ABS polymer in the sample;

(5) performing nuclear magnetic resonance hydrogen spectrum test on the ABS polymer;

(6) the percentage content is calculated from the ratio of the respective peak areas according to the difference of the peak positions of the respective functional groups of the three monomers.

In some preferred embodiments, the sample in step (1) is in the form of a number of small blocks of size 5mm by 2 mm.

In some preferred embodiments, the apparatus for raman spectroscopic qualitative analysis in step (2) is a confocal micro-raman spectrometer, and the test conditions are as follows: the laser wavelength is 632.8nm, the confocal hole is 400 μm, the slit is 100 μm, the grating is 650g/mm, the microscope lens is 50 times, and the scanning range is 100-3200cm^-1Resolution 2cm^-1The scan time is 2 s.

Through a Raman spectrum test, the components of the regenerated ABS plastic can be identified by Raman spectrum peaks in a test result, and the characteristic peaks of the polystyrene are as follows: C-H stretching vibration peak on benzene ring, C-H stretching vibration peak on ethylene chain, and vibration peak on benzene ring skeleton; the characteristic peaks of polyacrylonitrile are: stretching vibration peak of cyano C ≡ N; the polybutadiene characteristic peak is unsaturated C-H stretching vibration peak connected with alkene carbon, C ═ C double bond symmetric stretching vibration peak; if other substances exist, other characteristic peaks also appear, and specific substances are confirmed according to the spectrogram.

In some preferred embodiments, the apparatus for thermal gravimetric analysis in step (3) is TA instruments Q500, and the test conditions are: the flow rate of nitrogen atmosphere is 50mL/min, the temperature range is 25-900 ℃, and the heating speed is 20 ℃/min.

Based on the thermal weight loss analysis, the components in the regenerated ABS plastic can be judged through the decomposition reaction and the weight loss rate of each stage, the ABS polymer is decomposed within the range of 270-500 ℃, and whether the regenerated ABS plastic contains inorganic additives can be judged through the weight loss rate and residues of the thermal weight loss test.

The ABS plastic is transparent, while the recycled ABS plastic is generally black, because some carbon black or other inorganic matters are inevitably introduced in the recycling process, in order to make the data measurement of each monomer of the ABS polymer more accurate, the recycled ABS plastic needs to be extracted. In some preferred embodiments, the specific operation of extracting the ABS polymer in step (4) is: dissolving a sample by adopting a proper solvent, then filtering and centrifugally separating the solution, removing carbon black or other inorganic matters possibly existing in the solution to obtain an ABS polymer solution, and drying the ABS polymer solution to volatilize the solvent completely to obtain the ABS polymer.

In some preferred embodiments, the solvent is one of chloroform and dichloromethane, because chloroform and dichloromethane can dissolve the ABS plastic well and are volatile, and can be removed by drying without affecting subsequent measurements.

In some preferred embodiments, the apparatus used for the hydrogen nuclear magnetic resonance spectroscopy in step (5) is model DRX 400MHz of Bruker under the test conditions of magnetic field strength of 9.2T, nuclear magnetic tube diameter of 5mm, deuterated chloroform as a solvent, TMS as an internal nuclear magnetic resonance standard reagent, and temperature of 120 ℃.

Deuterated chloroform (CDCl3) is a deuterated product of chloroform, a colorless deuterated solvent, and is often used as a reagent for nuclear magnetic instruments. This is because it has better solubility for the recycled ABS plastic sample and its residual signal peaks do not interfere with the signal peaks of the sample.

In some preferred embodiments, the nuclear magnetic resonance hydrogen spectrum test has an operating frequency of 400.15MHz, a spectrum width of 8010.54Hz, a pulse width of 10 mus, a pulse delay of 2s, and 16 sampling times.

In some preferred embodiments, the sample for the nmr spectroscopy test is: and dissolving the ABS polymer in the deuterated chloroform solvent to prepare a solution with the concentration of 2.5-4% by mass fraction.

In some preferred embodiments, the TMS has a volume fraction of 0.05-0.2%.

TMS is tetramethylsilane, and because silicon has low electronegativity and has small influence on hydrogen atoms on four methyl groups, the TMS can give a strong signal and a sharp absorption peak in a nuclear magnetic resonance spectrum, and proton absorption peaks in other general organic compounds appear on the left side of the TMS. Therefore, it is common to use TMS as an internal standard for chemical shift in nuclear magnetic resonance spectroscopy and set its chemical shift to zero

Tetramethylsilane serves to calibrate the chemical shift zero in the 1H, 13C and 29Si spectra of the nuclear magnetic resonance spectrum. Since the 12 hydrogens of tetramethylsilane are identical, the 4 carbons are also equivalent, so that tetramethylsilane exhibits a single peak in both the H spectrum and the fully decoupled C spectrum, while almost all compounds currently studied using the H and C spectra have chemical shifts at low fields (i.e., greater chemical shifts) of the tetramethylsilane peak that do not interfere with each other.

The present invention will be specifically described below by way of examples. It is to be noted that the following examples are only intended to illustrate the present invention and should not be construed as limiting the scope of the present invention.

Example 1

The invention provides a method for detecting the composition content of each monomer unit in regenerated ABS plastic, which comprises the following steps:

(1) cutting samples from the regenerated ABS plastic into a plurality of small blocks with the size of 5mm by 2 mm;

(2) taking a small piece of sample from the prepared samples for Raman spectrum analysis, confirming that the main component is ABS according to a vibration peak appearing in a spectrogram, and meanwhile, judging whether other components exist;

(3) weighing 15mg of ABS recycled plastic sample, putting the ABS recycled plastic sample into a platinum disk containing the sample, and carrying out thermogravimetric analysis on the sample under the following test conditions: scanning at the initial temperature of 25 ℃ and the heating speed of 20 ℃/min, wherein the scanning temperature range is 25-900 ℃, the nitrogen atmosphere is adopted, and the flow rate is 50 mL/min;

(4) extracting an ABS polymer in the regenerated ABS plastic, putting a proper amount of sample into dichloromethane for dissolving, then filtering and centrifugally separating the solution to remove carbon black or other inorganic matters possibly existing in the solution to obtain an ABS polymer solution, and drying the ABS polymer solution to completely volatilize the solvent to obtain the ABS polymer;

(5) and (2) carrying out nuclear magnetic resonance hydrogen spectrum test on the ABS polymer, weighing about 50mg of sample, placing the sample in a deuterated chloroform solvent for dissolving to prepare a solution with the mass fraction of 2.5%, placing the dissolved sample into a 5mm nuclear magnetic tube, adding a TMS internal standard reagent with the prepared volume fraction of 0.15%, and carrying out ultrasonic vibration for 2 minutes to remove bubbles and partial oxygen in the sample. The test was carried out by the following test conditions: the working frequency is 400.15MHz, the spectrum width is 8010.54Hz, the pulse width is 10 mus, the pulse delay is 2s, and the sampling is carried out for 16 times;

(6) the percentage content is calculated from the ratio of the respective peak areas according to the difference of the peak positions of the respective functional groups of the three monomers.

Specifically, the content of the three monomers in the ABS polymer can be calculated by the following formula:the unit is mg/mg;

wherein Az and Ai represent the areas of the signal peaks selected for the ABS polymer and the internal standard, respectively;

ni and Nz are the number of certain monomer and internal standard proton corresponding to the integrated peak of ABS polymer and internal standard respectively;

mx and Mi are the molecular weights of a certain monomer and internal standard, respectively;

wi and Wx are the masses of the weighed sample and internal standard;

P_iis the purity of the internal standard.

The precision and accuracy of the detection method for the composition content of each monomer unit in the regenerated ABS plastic provided by the invention are verified as follows:

1. detection of precision

Selecting a certain regenerated ABS plastic to test according to the method, calculating the contents of A (acrylonitrile), B (butadiene) and S (styrene) after integrating the corresponding peak areas of the obtained nuclear magnetic resonance hydrogen spectrum, and repeating the measurement for 6 times, wherein the results are shown in Table 1:

TABLE 1 results of precision measurement

As shown in the results of Table 1, the precision of each monomer content in the ABS polymer measured by the method provided by the invention is good, and the precision requirement is met.

2. Accuracy detection

An ABS polymer of known composition was selected for accuracy testing and the results are shown in table 2:

TABLE 2 accuracy test results

Composition of	Known composition	Test results	Recovery rate
				wt％(A)	25.2	24.6～27.9	97.6％～110.7％
wt％(B)	32.3	30.7～34.6	95.05％～107.1％
				wt％(S)	42.5	41.9～44.3	98.6％～104.2％

As can be seen from the results in Table 2, the method provided by the present invention provides a better accuracy of the monomer content in the ABS polymer.

It should be clear that the scope of the present invention is not limited to the particular embodiments described above, but that modifications and variations are possible to those skilled in the art in light of the above teachings, all of which are intended to fall within the scope of the appended claims.