Quantitative nuclear magnetic carbon spectrum valuing method for azido polyether branching degree standard substance

Abstract

The invention provides a quantitative NMR (nuclear magnetic resonance) carbon spectrum valuing method of an azide polyether branching degree standard substance, which is based on quantitative NMR and directly values the branching degree of the azide polyether branching degree standard substance under the condition of not using an internal standard substance. Compared with the existing branching degree valuing method, such as a differential scanning calorimetry and a gel chromatography, the valuing method disclosed by the invention does not need an internal standard or an external standard, does not need to establish a calibration measurement curve, is simple and convenient in data processing and calculation, high in detection sensitivity and good in valuing accuracy, can realize unattended operation and stable operation in the testing process, and is suitable for large-scale popularization and application. The method is suitable for valuing the azide polyether branching degree standard substance.

Description

Technical Field

[0001] The invention belongs to the technical field of energetic material measurement, relates to azide polyether, and specifically relates to a quantitative nuclear magnetic resonance carbon spectrum determination method for azide polyether branching degree standard substance. Background Art

[0002] Azide polyether is an important adhesive containing an azido (-N3) functional group and is widely used in solid propellants and other fields. Azide polyethers with a certain degree of branching can avoid crystallization, and the cross-linked topological structure formed can improve the strength and toughness (tensile strength and elongation at break) of the composite system. The degree of branching (DB) of hyperbranched azide polyethers is between 0 and 1. The larger the DB value, the closer its topological structure is to the tree-like homologues, and the smaller the DB value, the closer its topological structure is to the linear homologues. Azide polyether branching standard substances are mainly used for calibration of azide polyether-related measuring equipment, measurement method evaluation or material assignment and other testing and metrology processes. Therefore, it is necessary to accurately determine its characteristic value, namely the degree of branching, at specified time intervals and environmental conditions.

[0003] There are two entry points for determining the degree of branching at home and abroad: based on the response of the degree of branching of polymers to physical parameters and based on the response of the branch chemical structure to the spectrum. Methods for determining the degree of branching based on the response of the degree of branching of polymers to physical parameters include differential scanning calorimetry (DSC), gel permeation chromatography (GPC)-light scattering detector coupling, etc. DSC can directly obtain the distribution of branches in the main chain of polymers, but because the melting temperature and the length of the crystalline segment are not a simple linear relationship, the enthalpy distribution in DSC does not directly correspond to the number of crystalline segments, so the DSC method only relatively characterizes the degree of branching of the same polymer system. The GPC method determines the degree of branching by detecting the difference in physical properties of branched polymers relative to linear polymers of the same relative molecular mass. The determination results of this method are strongly dependent on the selected linear reference material, so there is a certain determination error. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a quantitative nuclear magnetic resonance carbon spectrum determination method for azide polyether branching degree standard substance, so as to solve the technical problem that the simplicity and accuracy of the determination method in the prior art are difficult to be taken into account.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0006] The invention discloses a quantitative nuclear magnetic resonance carbon spectrum determination method for an azido polyether branching degree standard substance. The method is based on quantitative nuclear magnetic resonance and directly determines the branching degree of the azido polyether branching degree standard substance without using an internal standard substance.

[0007] The method comprises the following steps:

[0008] Step 1: Configure the NMR sample tube:

[0009] In a 5 mm diameter NMR sample tube, weigh 15-30 mg of azide polyether branching degree standard material, add 600 μL of deuterated dimethyl sulfoxide, ultrasonically dissolve and let stand for 4-6 hours, shake well and seal to obtain a configured NMR sample tube.

[0010] Step 2: Determine the quantitative NMR spectrum:

[0011] The NMR sample tube prepared in step 1 is placed in a superconducting NMR spectrometer to measure the quantitative NMR spectrum of the sample solution in the NMR sample tube.

[0012] Step 3: Determination of standard material value:

[0013] The quantitative nuclear magnetic resonance spectrum obtained in step 2 is subjected to baseline correction, phase correction and chemical shift correction, and the quantitative peaks of the quantitative nuclear magnetic resonance spectrum are respectively integrated, and the branching degree of the azide polyether branching degree standard substance is finally calculated based on the integrated area.

[0014] The calculation formula of the degree of branching is as follows:

[0015] DB=(A D +A T ) / (A D +A T +A L ).

[0016] Where:

[0017] DB represents the branching degree of the azidopolyether branching degree standard substance;

[0018] A D Represents the peak area of ​​the characteristic signal peak of the tree-like branching unit;

[0019] A T represents the peak area of ​​the characteristic signal peak of the terminal unit;

[0020] A L Represents the peak area of ​​the linear unit characteristic signal peak.

[0021] The present invention also has the following technical features:

[0022] In step 1, the deuteration degree of deuterated dimethyl sulfoxide is above 99%.

[0023] In step 1, the degree of branching of the azide polyether branching standard substance is 0.2 to 0.5.

[0024] In step 2, the nuclear magnetic resonance test parameters and conditions of the superconducting nuclear magnetic resonance spectrometer are: observation frequency 800.1 MHz, pulse sequence zgig or C13ig, measurement temperature 298K, relaxation time 2s, and scanning times 1024 to 2048.

[0025] In step 3, the quantitative peaks are the main chain and side chain methylene characteristic peaks with carbon spectrum chemical shifts of 23.22 ppm, 22.59 ppm and 22.02 ppm.

[0026] The method also includes step four.

[0027] Step 4: Get the expanded uncertainty:

[0028] Obtain the uncertainty of the degree of branching of the azido polyether branching standard substance obtained in step 3; the uncertainty is:

[0029] Where:

[0030] u C Indicates uncertainty;

[0031] u B Represents the uncertainty component introduced by the setting process;

[0032] u A It represents the repeatability uncertainty component introduced by the collaborative determination among laboratories;

[0033] u s It represents the uncertainty component caused by the stability of the standard material of branching degree of polyazide ether;

[0034] u bb It represents the uncertainty component caused by the heterogeneity of the standard material of azide polyether branching degree.

[0035] Based on uncertainty, when the confidence probability is set to 95%, the coverage factor k = 2, then the expanded uncertainty U c for.

[0036] U C =ku C .

[0037] Compared with the prior art, the present invention has the following technical effects:

[0038] (I) Compared with the existing branching degree determination methods, such as differential scanning calorimetry, gel chromatography and the like, the determination method of the present invention does not require an internal standard or an external standard, does not require the establishment of a calibration measurement curve, is simple in data processing and calculation, has high detection sensitivity and good determination accuracy, and can realize unattended and stable operation of the test process, and is suitable for the determination of branching degree standard substances of azide polyethers.

[0039] (II) The present invention establishes a quantitative nuclear magnetic resonance carbon spectroscopy determination method for the branching degree of polyazide standard substances with accurate and reliable characteristic value determination. The method uses nuclear magnetic resonance carbon spectroscopy to directly and accurately quantify the branching degree of the standard substance, and has the advantages of simple operation, mild test conditions, small test dosage, and good repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The molecular structure of the standard substance for branching degree of polyazide ether and the corresponding quantitative NMR carbon spectrum.

[0041] Figure 2 It is the branching degree quantitative spectrum peak of the standard substance of polyazide branching degree.

[0042] The specific contents of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0043] It should be noted that, unless otherwise specified, all of the equipment and technical methods in the present invention adopt equipment and technology known in the prior art.

[0044] Quantitative NMR carbon spectroscopy ( 13 C NMR) is a direct quantitative method based on polymer structure. 13 The half-peak width of the C NMR spectrum is narrow and the chemical shift distribution range is wide. The measurement error caused by the possible difference in relaxation time of C atoms in the polymer main chain and side chains can be minimized by adding relaxation reagents and using small-angle pulse sampling.

[0045] The main chain and the branch chain 13 If signal overlap occurs in the C NMR spectrum, it can be effectively analyzed by increasing the field strength of the NMR instrument or combining it with a two-dimensional NMR spectrum. 13 In the C NMR spectrum, the characteristic signals of the polymer main chain and side chain can be accurately attributed and integrated, and the branching degree standard material of azide polyether can be accurately determined without destroying the sample or having a calibration curve.

[0046] The present invention discloses a quantitative nuclear magnetic resonance carbon spectrum determination method for azide polyether branching degree standard substance. The method is based on quantitative nuclear magnetic resonance ( 13 C NMR), without using an internal standard, the degree of branching of the azidopolyether branching standard material was directly determined.

[0047] In accordance with the above technical scheme, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical scheme of this application fall within the protection scope of the present invention.

[0048] Embodiment 1:

[0049] This example provides a method for quantitative nuclear magnetic resonance carbon spectrum determination of azide polyether branching degree standard substance, which comprises the following steps:

[0050] Step 1: Configure the NMR sample tube:

[0051] In a 5 mm diameter NMR sample tube, weigh 20 mg of azide polyether branching degree standard material, add 600 μL of deuterated dimethyl sulfoxide (dDMSO), ultrasonically dissolve and let stand for 4.5 h, shake well and seal to obtain a configured NMR sample tube.

[0052] In step 1, the deuteration degree of deuterated dimethyl sulfoxide is above 99%.

[0053] In this embodiment, the branching degree of the azide polyether branching degree standard substance is 0.2 to 0.3.

[0054] Step 2: Determine the quantitative NMR spectrum:

[0055] The NMR sample tube prepared in step 1 is placed in a superconducting NMR spectrometer to measure the quantitative NMR spectrum of the sample solution in the NMR sample tube.

[0056] In step 2, the nuclear magnetic resonance test parameters and conditions of the superconducting nuclear magnetic resonance spectrometer are: observation frequency 800.1 MHz, pulse sequence zgig, measurement temperature 298 K, relaxation time 2 s, and scan number 1600.

[0057] In this embodiment, the superconducting nuclear magnetic resonance spectrometer adopts a Bruker 800 MHz superconducting nuclear magnetic resonance spectrometer (BRUKER, Germany).

[0058] Step 3: Determination of standard material value:

[0059] The quantitative nuclear magnetic resonance spectrum obtained in step 2 is subjected to baseline correction, phase correction and chemical shift correction, and the quantitative peaks of the quantitative nuclear magnetic resonance spectrum are respectively integrated, and the branching degree of the azide polyether branching degree standard substance is finally calculated based on the integrated area.

[0060] The calculation formula of branching degree is as follows:

[0061] DB=(A D +A T ) / (A D +A T +A L ).

[0062] Where:

[0063] DB represents the branching degree of the azidopolyether branching degree standard substance;

[0064] A D represents the peak area of ​​the characteristic signal peak of the dendritic branching unit (23.22 ppm);

[0065] A T represents the peak area of ​​the characteristic signal peak of the terminal unit (22.59 ppm);

[0066] A L It represents the peak area of ​​the characteristic signal peak of the linear unit (22.02 ppm).

[0067] In step 3, the quantitative peaks are the main chain and side chain methylene characteristic peaks with carbon spectrum chemical shifts of 23.22 ppm, 22.59 ppm, and 22.02 ppm.

[0068] Specifically, in this embodiment, the collected 13 C NMR spectra were calibrated with chemical shifts (using DMSOδ C 39.6ppm as the reference), baseline correction and phase adjustment ( Figure 1 ).according to 13 C NMR spectrum literature data, combined with the chemical structure of azide polyether, corresponding attribution ( Figure 2 ), the chemical shift of 23.22ppm is the characteristic signal peak of the tree-like branching unit, 22.59ppm is the characteristic signal peak of the terminal unit, and 22.02ppm is the characteristic signal peak of the linear unit. The three groups of characteristic signal peaks are well separated, which meets the principle of quantitative NMR characteristic peak selection.

[0069] Step 4: Get the expanded uncertainty:

[0070] Obtain the uncertainty of the degree of branching of the azido polyether branching standard substance obtained in step 3; the uncertainty is:

[0071] Where:

[0072] u C Indicates uncertainty;

[0073] u B Represents the uncertainty component introduced by the setting process;

[0074] u A It represents the repeatability uncertainty component introduced by the collaborative determination among laboratories;

[0075] u s It represents the uncertainty component caused by the stability of the standard material of branching degree of polyazide ether;

[0076] u bb It represents the uncertainty component caused by the heterogeneity of the standard material of azide polyether branching degree.

[0077] In this step, when using quantitative NMR carbon spectroscopy to determine the value of nitrogen polyether branching standard substances, in order to achieve the best estimate of its "true value", it is necessary to cooperate with multiple laboratories to determine the value. The sources of uncertainty include: ① The uncertainty component introduced in the determination process (u B );② Repeatability uncertainty component introduced by inter-laboratory cooperative determination (u A );③Uncertainty component caused by the stability of the standard material (u s );④Uncertainty component caused by the inhomogeneity of the standard material (u bb ). The uncertainty component introduced by the determination process adopts Class B assessment, the uncertainty component introduced by the inter-laboratory cooperative determination adopts Class A assessment, and the uncertainty introduced by the inhomogeneity and instability can be obtained by the uniformity and stability test of the branching degree standard material of polyazide ether. The various uncertainty components are synthesized to obtain the synthetic uncertainty.

[0078] Based on uncertainty, when the confidence probability is set to 95%, the coverage factor k = 2, then the expanded uncertainty U C for;

[0079] U C =ku C .

[0080] Specifically, in this embodiment, 6 laboratories were selected to perform 12 parallel measurements on the experimental samples, and the determination results are shown in Table 1.

[0081] Table 1 Branching degree quantitative results of standard substances of polyazide ether branching degree

[0082]

[0083]

[0084] First, perform a normal distribution test on the degree of branching:

[0085] The known Shapiro-Wilk method is selected to test the normal distribution of the data. The statistic of the Shapiro-Wilk test is:

[0086]

[0087] The test data of laboratory 1 were used as an example to test the normal distribution of data, and the results are shown in Table 2. The test data of other laboratories were tested by the same method and all showed normal distribution.

[0088] Table 2 Shapiro-Wilk test calculation results

[0089]

[0090]

[0091] Second, perform a test on the suspicious value of the branching degree within the group:

[0092] The known Dixon method is used to test suspicious values ​​within the group.

[0093] Arrange each set of measurement results in ascending order, X (1) ≤xX (2) ≤……≤X (n-1) ≤X (n) ; Calculate r1 and r according to the following formula: n .

[0094]

[0095] From the table, we get f(0.05,12)=0.583. If r1>r n , and r1>f(0.05,12), then determine X (1) is an outlier and should be removed; if r n >r1, and r n >f(0.05,12), then determine X (n) is an outlier and should be removed; if r1, r n If all are less than f(0.05,12), all data are retained. n The maximum value is less than f(0.05,12), and all data should be retained.

[0096] Third, conduct uncertainty analysis of branching degree determination:

[0097] Using quantitative 13 CNMR test principle The uncertainty sources of the target branching characteristic value are as follows: ① The uncertainty component introduced by the determination process (u B );② Repeatability uncertainty component introduced by inter-laboratory cooperative determination (u A );③Uncertainty component caused by the stability of the standard material (u s );④Uncertainty component caused by the inhomogeneity of the standard material (u bb ).

[0098] The uncertainty components are synthesized and the combined uncertainty is:

[0099]

[0100] When the confidence probability is 95%, the coverage factor k=2, then the expanded uncertainty is:

[0101] U C =ku C (k=2)

[0102] Because the NMR method has no correlation with the mass of the sample, the uncertainty of the balance weighing is not considered in the uncertainty component. 13 In the process of determining the target degree of branching by C NMR, the uncertainty mainly comes from the uncertainty introduced by the integral of the characteristic peak, and is also related to the processing of background signals, the selection of measurement parameters, the selection of characteristic quantitative peaks, and signal analysis and processing. The uncertainty caused by the test process is obtained by evaluating the uncertainty of each operating unit separately and then synthesizing it. This can effectively simplify the evaluation procedure and avoid repeated evaluation. Therefore, the uncertainty component introduced in the determination process adopts Class B assessment. According to test experience and previous test data, the uncertainty introduced in the determination process is u B =0.0012.

[0103] The repeatability uncertainty component introduced by the cooperative determination between laboratories is calculated according to the formula The calculated uncertainty is: 0.00052.

[0104] For the deviation caused by the long-term stability of the sample, the uncertainty of long-term stability u during the one-year storage period is calculated according to ISO35:2006 s =s(b)×t=0.0033.

[0105] Analyze uniformity test data, if uniformity evaluation data Then u bb >s bb The uncertainty component caused by inhomogeneity is:

[0106]

[0107] like The uncertainty component caused by inhomogeneity is:

[0108]

[0109] in:

[0110] represents the sum of variances between groups;

[0111] represents the within-group variance and:

[0112] n represents the number of measurements per group;

[0113] express Degrees of freedom.

[0114] Substitute into the formula and calculate: u bb =0.01.

[0115] The uncertainty component values ​​of the branching degree of the standard substance are shown in Table 3:

[0116] Table 3 Uncertainty of setting value

[0117]

[0118] Taking the expanded uncertainty factor k=2, the expanded uncertainty is 0.0076.

[0119] In summary, using 13 The results of C NMR determination of the hyperbranched polyazide standard substance with a characteristic quantity branching degree of 0.2-0.3 are as follows: the branching degree is 0.26 and the expanded uncertainty is 0.0076.

[0120] Embodiment 2:

[0121] This example provides a method for quantitative nuclear magnetic resonance carbon spectrum determination of azide polyether branching degree standard substance, which comprises the following steps:

[0122] Step 1: Configure the NMR sample tube:

[0123] In a 5 mm diameter NMR sample tube, weigh 10 mg of azide polyether branching degree standard substance, add 600 μL of deuterated dimethyl sulfoxide (dDMSO), ultrasonically dissolve and let stand for 4.5 h, shake well and seal to obtain a configured NMR sample tube.

[0124] In step 1, the deuteration degree of deuterated dimethyl sulfoxide is above 99%.

[0125] In this embodiment, the branching degree of the azide polyether branching degree standard substance is 0.4 to 0.5.

[0126] Step 2: Determine the quantitative NMR spectrum:

[0127] The NMR sample tube prepared in step 1 is placed in a superconducting NMR spectrometer to measure the quantitative NMR spectrum of the sample solution in the NMR sample tube.

[0128] In step 2, the nuclear magnetic resonance test parameters and conditions of the superconducting nuclear magnetic resonance spectrometer are: observation frequency 800.1 MHz, pulse sequence C13ig, measurement temperature 298 K, relaxation time 2 s, and scan number 2048.

[0129] In this embodiment, the superconducting nuclear magnetic resonance spectrometer adopts a Bruker 800 MHz superconducting nuclear magnetic resonance spectrometer (BRUKER, Germany).

[0130] Step 3: Determination of standard material value:

[0131] The quantitative nuclear magnetic resonance spectrum obtained in step 2 is subjected to baseline correction, phase correction and chemical shift correction, and the quantitative peaks of the quantitative nuclear magnetic resonance spectrum are respectively integrated, and the branching degree of the azide polyether branching degree standard substance is finally calculated based on the integrated area.

[0132] The calculation formula of branching degree is as follows:

[0133] DB=(A D +A T ) / (A D +A T +A L ).

[0134] Where:

[0135] DB represents the branching degree of the azidopolyether branching degree standard substance;

[0136] A D represents the peak area of ​​the characteristic signal peak of the dendritic branching unit (23.22 ppm);

[0137] A T represents the peak area of ​​the characteristic signal peak of the terminal unit (22.59 ppm);

[0138] A L It represents the peak area of ​​the characteristic signal peak of the linear unit (22.02 ppm).

[0139] In step 3, the quantitative peaks are the main chain and side chain methylene characteristic peaks with carbon spectrum chemical shifts of 23.22 ppm, 22.59 ppm, and 22.02 ppm.

[0140] Specifically, in this embodiment, the collected 13 C NMR spectra were calibrated with chemical shifts (using DMSOδ C 39.6ppm as the reference), baseline correction and phase adjustment. 13 The literature data of C NMR spectrum were combined with the chemical structure of azide polyether for corresponding attribution. The chemical shift of 23.22ppm was the characteristic signal peak of the tree-like branching unit, 22.59ppm was the characteristic signal peak of the terminal unit, and 22.02ppm was the characteristic signal peak of the linear unit. The three groups of characteristic signal peaks were well separated, which met the principle of quantitative NMR characteristic peak selection.

[0141] Step 4: Get the expanded uncertainty:

[0142] Obtain the uncertainty of the degree of branching of the azido polyether branching standard substance obtained in step 3; the uncertainty is:

[0143] Where:

[0144] uC Indicates uncertainty;

[0145] u B Represents the uncertainty component introduced by the setting process;

[0146] u A It represents the repeatability uncertainty component introduced by the collaborative determination among laboratories;

[0147] u s It represents the uncertainty component caused by the stability of the standard material of branching degree of polyazide ether;

[0148] u bb It represents the uncertainty component caused by the heterogeneity of the standard material of azide polyether branching degree.

[0149] In this step, when using quantitative NMR carbon spectroscopy to determine the value of nitrogen polyether branching standard substances, in order to achieve the best estimate of its "true value", it is necessary to cooperate with multiple laboratories to determine the value. The sources of uncertainty include: ① The uncertainty component introduced in the determination process (u B );② Repeatability uncertainty component introduced by inter-laboratory cooperative determination (u A );③Uncertainty component caused by the stability of the standard material (u s );④Uncertainty component caused by the inhomogeneity of the standard material (u bb ). The uncertainty component introduced by the determination process adopts Class B assessment, the uncertainty component introduced by the inter-laboratory cooperative determination adopts Class A assessment, and the uncertainty introduced by the inhomogeneity and instability can be obtained by the uniformity and stability test of the branching degree standard material of polyazide ether. The various uncertainty components are synthesized to obtain the synthetic uncertainty.

[0150] Based on uncertainty, when the confidence probability is set to 95%, the coverage factor k = 2, then the expanded uncertainty U C for.

[0151] U C =ku C .

[0152] Specifically, in this embodiment, 6 laboratories were selected to perform 12 parallel measurements on the experimental samples, and the determination results are shown in Table 3.

[0153] Table 3 Branching degree quantitative results of standard substances of azide polyether branching degree

[0154]

[0155]

[0156] First, perform a normal distribution test on the degree of branching:

[0157] The known Shapiro-Wilk method is selected to test the normal distribution of the data. The statistic of the Shapiro-Wilk test is:

[0158]

[0159] The test data of laboratory 1 were used as an example to test the normal distribution of data, and the results are shown in Table 4. The test data of other laboratories were tested by the same method and all showed normal distribution.

[0160] Table 4 Shapiro-Wilk method test calculation results

[0161]

[0162] Second, perform a test on the suspicious value of the branching degree within the group:

[0163] The known Dixon method is used to test suspicious values ​​within the group.

[0164] Arrange each set of measurement results in ascending order, X (1) ≤xX (2) ≤……≤X (n-1) ≤X (n) ; Calculate r1 and r according to the following formula: n .

[0165]

[0166] From the table, we get f(0.05,12)=0.583. If r1>r n , and r1>f(0.05,12), then determine X (1) is an outlier and should be removed; if r n >r1, and r n >f(0.05,12), then determine X (n) is an outlier and should be removed; if r1, r n If all are less than f(0.05,12), all data are retained. n The maximum value is less than f(0.05,12), and all data should be retained.

[0167] Third, conduct uncertainty analysis of branching degree determination:

[0168] Using quantitative 13 C NMR test principle: The uncertainty sources of the target branching characteristic value are as follows: ① The uncertainty component introduced by the determination process (u B );② Repeatability uncertainty component introduced by inter-laboratory cooperative determination (u A );③Uncertainty component caused by the stability of the standard material (u s);④Uncertainty component caused by the inhomogeneity of the standard material (u bb ).

[0169] The uncertainty components are synthesized and the combined uncertainty is:

[0170]

[0171] When the confidence probability is 95%, the coverage factor k=2, then the expanded uncertainty is:

[0172] U C =ku C (k=2)

[0173] Because the NMR method has no correlation with the mass of the sample, the uncertainty of the balance weighing is not considered in the uncertainty component. 13 In the process of determining the target degree of branching by C NMR, the uncertainty mainly comes from the uncertainty introduced by the integral of the characteristic peak, and is also related to the processing of background signals, the selection of measurement parameters, the selection of characteristic quantitative peaks, and signal analysis and processing. The uncertainty caused by the test process is obtained by evaluating the uncertainty of each operating unit separately and then synthesizing it. This can effectively simplify the evaluation procedure and avoid repeated evaluation. Therefore, the uncertainty component introduced in the determination process adopts Class B assessment. According to test experience and previous test data, the uncertainty introduced in the determination process is u B =0.0012.

[0174] The repeatability uncertainty component introduced by the cooperative determination between laboratories is calculated according to the formula The calculated uncertainty is: 0.0007.

[0175] For the deviation caused by the long-term stability of the sample, the uncertainty of long-term stability u during the one-year storage period is calculated according to ISO35:2006 s =s(b)×t=0.00069.

[0176] Analyze uniformity test data, if uniformity evaluation data Then u bb >s bb The uncertainty component caused by inhomogeneity is:

[0177]

[0178] like The uncertainty component caused by inhomogeneity is:

[0179]

[0180] in:

[0181] represents the sum of variances between groups;

[0182] represents the within-group variance and:

[0183] n represents the number of measurements per group;

[0184] express degrees of freedom.

[0185] Substitute into the formula and calculate: u bb =0.013.

[0186] The uncertainty component values ​​of the branching degree of the standard substance are shown in Table 5:

[0187] Table 5 Uncertainty of determination

[0188]

[0189]

[0190] Taking the expanded uncertainty factor k=2, the expanded uncertainty is 0.014.

[0191] In summary, using 13 The determination results of C NMR for the hyperbranched polyazide standard substance with a characteristic quantity branching degree of 0.4-0.5 are as follows: the branching degree is 0.46 and the expanded uncertainty is 0.014.

Claims

1. A quantitative nuclear magnetic resonance carbon spectrum determination method for azide polyether branching degree standard substance, characterized in that: The method is based on quantitative nuclear magnetic resonance and directly determines the branching degree of azide polyether branching degree standard material without using an internal standard.

2. The quantitative nuclear magnetic resonance carbon spectrum determination method of the azido polyether branching degree standard substance as claimed in claim 1, characterized in that: The method comprises the following steps: Step 1: Configure the NMR sample tube: In a 5 mm diameter NMR sample tube, weigh 15-30 mg of polyazide branching standard material, add 600 μL of deuterated dimethyl sulfoxide, ultrasonically dissolve and let stand for 4-6 hours, shake well and seal to obtain a configured NMR sample tube; Step 2: Determine the quantitative NMR spectrum: Placing the NMR sample tube prepared in step 1 in a superconducting NMR spectrometer to measure a quantitative NMR spectrum of the sample solution in the NMR sample tube; Step 3: Determination of standard material value: The quantitative nuclear magnetic resonance spectrum obtained in step 2 is subjected to baseline correction, phase correction and chemical shift correction, and the quantitative peaks of the quantitative nuclear magnetic resonance spectrum are respectively integrated, and the branching degree of the azide polyether branching degree standard substance is finally calculated according to the integrated area; The calculation formula of the degree of branching is as follows: DB=(A D +A T ) / (A D +A T +A L ); Where: DB represents the branching degree of the azidopolyether branching degree standard substance; A D Represents the peak area of ​​the characteristic signal peak of the tree-like branching unit; A T represents the peak area of ​​the characteristic signal peak of the terminal unit; A L Represents the peak area of ​​the linear unit characteristic signal peak.

3. The quantitative nuclear magnetic resonance carbon spectrum determination method of the azido polyether branching degree standard substance as claimed in claim 2, characterized in that: In step 1, the deuteration degree of deuterated dimethyl sulfoxide is above 99%.

4. The quantitative nuclear magnetic resonance carbon spectrum determination method of the azido polyether branching degree standard substance as claimed in claim 2, characterized in that: In step 1, the branching degree of the azide polyether branching degree standard substance is 0.2 to 0.

5.

5. The quantitative nuclear magnetic resonance carbon spectrum determination method of the azido polyether branching degree standard substance as claimed in claim 2, characterized in that: In step 2, the nuclear magnetic resonance test parameters and conditions of the superconducting nuclear magnetic resonance spectrometer are: observation frequency 800.1 MHz, pulse sequence zgig or C13ig, measurement temperature 298K, relaxation time 2s, and scanning times 1024 to 2048.

6. The quantitative NMR carbon spectrum determination method of the azido polyether branching degree standard substance as claimed in claim 2, characterized in that: In step 3, the quantitative peaks are the main chain and side chain methylene characteristic peaks with carbon spectrum chemical shifts of 23.22 ppm, 22.59 ppm and 22.02 ppm.

7. The quantitative NMR carbon spectrum determination method of the azido polyether branching degree standard substance as claimed in claim 2, characterized in that: The method also includes step 4; Step 4: Get the expanded uncertainty: Obtain the uncertainty of the degree of branching of the azido polyether branching standard substance obtained in step 3; the uncertainty is: Where: u C Indicates uncertainty; u B Represents the uncertainty component introduced by the setting process; u A It represents the repeatability uncertainty component introduced by the collaborative determination among laboratories; u s It represents the uncertainty component caused by the stability of the standard material of branching degree of polyazide ether; u bb It represents the uncertainty component caused by the heterogeneity of the standard material of branching degree of polyazide ether; Based on uncertainty, when the confidence probability is set to 95%, the coverage factor k = 2, then the expanded uncertainty U C for; U C =stand C .

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