Quantitative evaluation method for viscoelasticity of polymer solution

Abstract

The invention relates to a method for quantitatively evaluating viscoelasticity of a polymer solution. The method mainly solves the problem that the existing polymer solution viscoelasticity determination result can only be qualitatively analyzed and cannot be quantitatively analyzed. The method comprises the following steps: S1, finding out a vibration frequency range when an energy storage modulus and an energy consumption modulus change regularly; s2, taking the energy storage modulus and the energy consumption modulus of one sample, and processing a detection result; s3, taking logarithms to obtain an energy storage modulus logarithmic value array and an energy consumption modulus logarithmic value array; s4, averaging to obtain the average number of the log value array of the energy storage modulus and the average number of the log value array of the energy consumption modulus; s5, solving an inverse logarithm to obtain a logarithm average energy storage modulus and a logarithm average energy consumption modulus; drawing, comparing and analyzing. According to the method, qualitative analysis can be simplified into intuitive and convenient quantitative analysis, so that the influence degree and rule system of different factors on the viscoelasticity of the polymer solution can be obtained.

Description

Technical field:

[0001] The invention relates to the technical field of indoor experimental analysis, and in particular to a method for quantitatively evaluating the viscoelasticity of a polymer solution. Background technology:

[0002] Due to the long-chain structure of polymer macromolecules and the gradual nature of macromolecular motion, the deformation and flow of polymer solutions are not purely viscous or purely elastic. This comprehensive property of both viscosity and elasticity is called viscoelasticity. There are many parameters used to characterize the viscoelasticity of fluids, such as relaxation time, Weisenberg number, storage modulus, first normal stress difference, etc. One method of using a rheometer to measure viscoelasticity is to characterize its viscosity and elasticity respectively by measuring the loss modulus and storage modulus of the liquid at different vibration frequencies. The measurement results are presented as a curve of the change of storage modulus and loss modulus with vibration frequency. However, when comparing and analyzing the viscoelasticity of multiple samples, this way of expression can only qualitatively analyze that a certain sample has higher viscoelasticity than other samples, and cannot quantitatively give answers to questions such as "how much higher is the viscoelasticity of a certain sample than others" and "what kind of change pattern is there". Summary of the invention:

[0003] The present invention aims to solve the problem that the existing polymer solution viscoelasticity measurement results in the background technology can only be qualitatively analyzed and cannot achieve quantitative analysis of the viscoelasticity test results, and provide a method for quantitatively evaluating the viscoelasticity of a polymer solution. The method for quantitatively evaluating the viscoelasticity of a polymer solution can simplify the qualitative analysis into an intuitive and convenient quantitative analysis, thereby obtaining the degree and law of influence of different factors on the viscoelasticity of the polymer solution.

[0004] The present invention solves the problem by the following technical solution: The method for quantitatively evaluating the viscoelasticity of the polymer solution comprises the following steps:

[0005] S1. Determine the change factors of the sample group to be analyzed, measure the viscoelastic frequency scanning experimental data of the sample group, and find out the vibration frequency range when the common storage modulus and dissipation modulus change regularly, as the regular vibration frequency range for studying the viscoelasticity of the polymer solution;

[0006] S2. Based on the determined vibration frequency range, select the viscoelasticity test data of one sample from the sample group, take the logarithm of all data points on the storage modulus and dissipation modulus curves within the regular vibration frequency range, and obtain a storage modulus logarithm array and a dissipation modulus logarithm array;

[0007] S3, averaging the storage modulus logarithmic array and the energy loss modulus logarithmic array obtained in step S2, respectively, to obtain the average of the storage modulus logarithmic array and the average of the energy loss modulus logarithmic array of the sample;

[0008] S4, respectively calculating the antilogarithm of the average of the storage modulus logarithmic array and the average of the logarithmic array of the energy loss modulus of the sample in step S3, so as to obtain the logarithmic average storage modulus and the logarithmic average energy loss modulus of the sample;

[0009] S5. For other multiple comparative analysis samples, after processing according to steps S2 to S4, the logarithmic average storage modulus and the logarithmic average energy loss modulus of each sample are obtained, so as to quantitatively analyze the change law of viscoelasticity.

[0010] Preferably, the method for finding the vibration frequency range when the storage modulus and the loss modulus change regularly in step S1 is:

[0011] Find out the critical vibration frequency at which the storage modulus and the energy loss modulus show fluctuations. The data less than or equal to the critical vibration frequency is the required vibration frequency range; data points greater than the critical vibration frequency will not participate in the subsequent calculations.

[0012] Preferably, the viscoelastic frequency scanning experimental data of the sample group in step S1 includes a monitoring array of the change of storage modulus with frequency.

[0013] Preferably, the viscoelastic frequency scanning experimental data of the sample group in step S1 also includes a monitoring array of the change of the energy loss modulus with frequency.

[0014] Preferably, the logarithmic value formula of the storage modulus in step S2 is: i =logG′ i ;

[0015] Where: A i is the logarithmic value of the storage modulus of the sample at the i-th point within the vibration frequency range with a regular change trend;

[0016] G' i It is the storage modulus of the sample at the i-th point within the vibration frequency range with a regular change trend.

[0017] Preferably, the formula for the logarithmic value of the energy loss modulus in step S2 is: i =logG" i

[0018] Where: B i is the logarithmic value of the energy dissipation modulus of the sample at the i-th point within the vibration frequency range with a regular change trend;

[0019] G” i It is the energy loss modulus of the sample at the i-th point within the vibration frequency range with a regular change trend.

[0020] Preferably, the average formula of the storage modulus logarithmic array in step S3 is:

[0021]

[0022] Where: is the average of the storage modulus logarithmic array; n is the number of data points of the sample within the vibration frequency range with a regular change trend; A i It is the logarithm of the storage modulus of the sample at the i-th point within the vibration frequency range that shows a regular change trend.

[0023] Preferably, the formula for the average of the energy loss modulus logarithmic array in step S3 is:

[0024]

[0025] Where: is the average of the logarithmic array of energy loss modulus; n is the number of data points of the sample within the vibration frequency range with a regular change trend; B i It is the logarithm of the energy dissipation modulus of the sample at the i-th point within the vibration frequency range that shows a regular change trend.

[0026] Preferably, the logarithmic mean storage modulus formula in step S4 is:

[0027]

[0028] The logarithmic average energy loss modulus formula of step S4 is:

[0029]

[0030] Where: A is the logarithmic average storage modulus; B is the logarithmic average energy loss modulus; is the average of the storage modulus logarithmic array; is the average of the energy dissipation modulus logarithmic array.

[0031] Preferably, the method for quantitatively analyzing the change law of viscoelasticity in step S5 is: taking the change factor of the sample group as the ordinate, and the logarithmic average storage modulus and the logarithmic average energy loss modulus as the abscissa, plotting the change curve of the logarithmic average storage modulus and the logarithmic average energy loss modulus with the change factor; by plotting the change curve, the influence of the change factor on the viscoelasticity of the polymer solution can be intuitively displayed.

[0032] Compared with the above background technology, the present invention has the following beneficial effects:

[0033] The method of the present invention is used to process and analyze multiple groups of viscoelasticity test results, and a curve of the change of polymer solution viscoelasticity with various factors is obtained. The range and influence trend of each factor that has a strong influence on the viscoelasticity of the polymer are circled intuitively, quickly and quantitatively, which is convenient for guiding the control of the factor during subsequent on-site implementation to ensure that the injected polymer solution exerts the maximum viscoelastic advantage, and effectively solves the problem that the viscoelasticity results can only be analyzed qualitatively and cannot provide specific guidance on the site. Description of the drawings:

[0034] Attached Figure 1 is a flow chart of a quantitative evaluation method of viscoelasticity of a polymer solution of the present invention;

[0035] Attached Figure 2 This is a result diagram of the storage modulus during conventional analysis of viscoelasticity of an embodiment of the present invention;

[0036] Attached Figure 3 This is a result diagram of the energy dissipation modulus during conventional viscoelastic analysis of an embodiment of the present invention;

[0037] Attached Figure 4 It is a result diagram of the quantitative analysis of viscoelasticity of an embodiment of the present invention. Specific implementation method:

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0039] like Figure 1 As shown, the method for quantitatively evaluating the viscoelasticity of a polymer solution of the present invention comprises the following steps:

[0040] S1. Determine the change factors of the sample group to be analyzed, measure the viscoelastic frequency scanning experimental data of the sample group, and find out the vibration frequency range when the common storage modulus and dissipation modulus change regularly, as the regular vibration frequency range for studying the viscoelasticity of the polymer solution;

[0041] Find the vibration frequency range when the storage modulus and dissipation modulus change regularly. When the vibration frequency is greater than a certain value, the storage modulus and dissipation modulus show irregular fluctuations, and it is meaningless to study the viscoelasticity of the solution at this time. Therefore, when analyzing, find the critical vibration frequency at which the storage modulus and dissipation modulus show fluctuations. The data less than or equal to the critical vibration frequency is the required vibration frequency range; data points greater than the critical vibration frequency will not participate in the subsequent calculations.

[0042] The viscoelastic frequency scanning experimental data of the sample group includes a monitoring array of storage modulus variation with frequency and a monitoring array of energy loss modulus variation with frequency.

[0043] S2. Based on the determined vibration frequency range, select the viscoelasticity test data of one sample from the sample group, take the logarithm of all data points on the storage modulus and dissipation modulus curves within the regular vibration frequency range, and obtain a storage modulus logarithm array and a dissipation modulus logarithm array;

[0044] The logarithmic formula of the storage modulus is: i =logG′ i ;

[0045] Where: A i G' is the logarithmic value of the storage modulus of the sample at the i-th point within the vibration frequency range with a regular change trend; i It is the storage modulus of the sample at the i-th point within the vibration frequency range with a regular change trend.

[0046] The formula for the logarithmic value of the energy loss modulus is: i =logG" i

[0047] Where: B i is the logarithmic value of the energy dissipation modulus of the sample at the i-th point within the vibration frequency range with a regular change trend; G” i It is the energy loss modulus of the sample at the i-th point within the vibration frequency range with a regular change trend.

[0048] S3, averaging the storage modulus logarithmic array and the energy loss modulus logarithmic array obtained in step 2, respectively, to obtain the average of the storage modulus logarithmic array and the average of the energy loss modulus logarithmic array of the sample;

[0049] The average formula of the storage modulus logarithmic array is:

[0050]

[0051] Where: is the average of the storage modulus logarithmic array; n is the number of data points of the sample within the vibration frequency range with a regular change trend; A i It is the logarithm of the storage modulus of the sample at the i-th point within the vibration frequency range that shows a regular change trend.

[0052] The formula for the average of the energy loss modulus logarithmic array is:

[0053]

[0054] Where: is the average of the logarithmic array of energy loss modulus; n is the number of data points of the sample within the vibration frequency range with a regular change trend; B iIt is the logarithm of the energy dissipation modulus of the sample at the i-th point within the vibration frequency range that shows a regular change trend.

[0055] S4, respectively calculating the antilogarithm of the average of the storage modulus logarithmic array and the average of the logarithmic array of the energy loss modulus of the sample in step 3, so as to obtain the logarithmic average storage modulus and the logarithmic average energy loss modulus of the sample;

[0056] The logarithmic mean storage modulus formula is:

[0057]

[0058] The logarithmic average energy loss modulus formula is:

[0059]

[0060] Where: A is the logarithmic average storage modulus; B is the logarithmic average energy loss modulus; is the average of the storage modulus logarithmic array; is the average of the energy dissipation modulus logarithmic array.

[0061] S5. For other comparative analysis samples, after processing according to steps 2-4, the logarithmic average storage modulus and logarithmic average energy loss modulus of each sample are obtained, so as to quantitatively analyze the change law of viscoelasticity.

[0062] The method for quantitatively analyzing the changing law of viscoelasticity is: taking the changing factor of the sample group as the vertical coordinate, taking the logarithmic average storage modulus and the logarithmic average energy loss modulus as the horizontal coordinate, and drawing the changing curve of the logarithmic average storage modulus and the logarithmic average energy loss modulus with the changing factor; by drawing the changing curve, the influence of the changing factor on the viscoelasticity of the polymer solution can be intuitively displayed.

[0063] Example 1

[0064] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0065] like Figure 1 As shown in FIG. 1 , a method for quantitatively evaluating the viscoelasticity of a polymer solution is described in detail by taking a set of experimental data on the effect of a variable factor x on the viscoelasticity of a polymer solution as an example:

[0066] Step 1: There are 6 samples in this group of experiments. When the vibration frequency is less than 2.783Hz, the storage modulus and energy loss modulus of all samples show a regular change. Therefore, the vibration frequency range of the viscoelastic regular change trend of this group of experimental data is 0.01-2.783HZ, and the data points with a frequency greater than 2.783Hz will not be included in the subsequent calculations.

[0067] Step 2: Take the viscoelastic test data of sample 1# for calculation.

[0068] The storage modulus of sample 1# at 0.01-0.783HZ is 0.002897Pa, 0.003963Pa, ..., 0.646Pa, respectively. After taking the logarithm, the logarithmic array of the storage modulus is obtained (-2.538, -2.402, ..., -0.190).

[0069] The energy loss modulus of sample 1# at 0.01-0.783HZ is 0.01717Pa, 0.02093Pa, ..., 0.621Pa respectively. After taking the logarithm, the energy loss modulus logarithmic array is obtained (-1.765, -1.679, ..., -0.207).

[0070] Step 3: The storage modulus logarithmic array of sample 1# obtained in step 2 is averaged to obtain -1.205, and the energy loss modulus logarithmic array is averaged to obtain -0.923.

[0071] Step 4: Take the antilogarithm of the averages in step 3 to obtain the logarithmic average storage modulus of sample 1#, which is 0.062 Pa, and the logarithmic average energy loss modulus, which is 0.119 Pa.

[0072] Step 5: After processing samples 2#-6# according to steps 2-4, their logarithmic average storage modulus and logarithmic average energy loss modulus are obtained respectively for quantitative comparative analysis. It is also possible to draw a change curve with the change factor x as the ordinate and the logarithmic average storage modulus and logarithmic average energy loss modulus as the abscissa, which can more clearly and intuitively show the influence of the change factor x on the viscoelasticity of the polymer solution.

[0073] The results of the quantitative analysis of viscoelasticity can be found in Figure 4 .Depend on Figure 4 It can be seen that when the concentration of variable factor x is between 8400mg / L and 10000mg / L, the logarithmic average storage modulus and the logarithmic average energy loss modulus decrease with the increase of the concentration of variable factor x, and the rate of decrease is relatively fast, indicating that in this range, the viscoelasticity of the polymer solution is greatly affected by the adverse effect of variable factor x. When the concentration of variable factor x is between 8400mg / L and 10000mg / L, the viscoelasticity of the polymer solution is affected by variable factor x more slowly, and the viscoelasticity improves slightly when the concentration reaches about 10000mg / L.

[0074] The invention is a convenient, intuitive and quantitative method for evaluating the viscoelasticity of a solution. The judgment result of the invention is clear and has good guiding significance for actual analysis.

[0075] Comparative Example 1

[0076] The conventional analysis method for the viscoelasticity of the six samples in this group of experiments is: plot the storage modulus and the loss modulus curves of the six samples against the vibration frequency in one graph, and observe and compare these curves. At the same frequency, the larger the storage modulus and the loss modulus, the better the viscoelasticity of the sample.

[0077] The results of conventional viscoelastic analysis are shown in Figure 2 , Figure 3 .from Figure 2 From the curve of the storage modulus of each sample with the vibration frequency, the storage modulus of sample No. 6 is much higher than that of other samples at the same frequency when the change factor x concentration is 5370 mg / L. The storage modulus of the other samples at the same frequency are not much different. Figure 3 From the curve of the energy modulus of each sample with the vibration frequency, it is still sample No. 6, when the concentration of the variable factor x is 5370mg / L, the energy modulus at the same frequency is the highest, while the others have certain differences, but the difference is not large. It can be seen that only a relatively qualitative conclusion can be drawn: when the concentration of the variable factor x is 5370mg / L, the viscoelasticity is the best, and when it reaches 7686mg / L, the viscoelasticity becomes significantly worse.

[0078] From the comparison between Example 1 and Comparative Example 1, it can be seen that, compared with conventional methods, the present invention can intuitively and conveniently find the influence rules of the viscoelasticity of the polymer solution by the changing factors, including the influence trend, range, amplitude, speed, etc., so as to facilitate the control of the factors during subsequent on-site implementation, so as to ensure that the injected polymer solution exerts the maximum viscoelastic advantage.

Claims

1. A method for quantitatively evaluating the viscoelasticity of a polymer solution, characterized in that: The following steps are involved: S1. Determine the change factors of the sample group to be analyzed, measure the viscoelastic frequency scanning experimental data of the sample group, and find out the vibration frequency range when the common storage modulus and dissipation modulus change regularly, as the regular vibration frequency range for studying the viscoelasticity of the polymer solution; S2. Based on the determined vibration frequency range, select the viscoelasticity test data of one sample from the sample group, take the logarithm of all data points on the storage modulus and dissipation modulus curves within the regular vibration frequency range, and obtain a storage modulus logarithm array and a dissipation modulus logarithm array; S3, averaging the storage modulus logarithmic array and the energy loss modulus logarithmic array obtained in step S2, respectively, to obtain the average of the storage modulus logarithmic array and the average of the energy loss modulus logarithmic array of the sample; S4, respectively calculating the antilogarithm of the average of the storage modulus logarithmic array and the average of the logarithmic array of the energy loss modulus of the sample in step S3, so as to obtain the logarithmic average storage modulus and the logarithmic average energy loss modulus of the sample; S5. For other multiple comparative analysis samples, after processing according to steps S2 to S4, the logarithmic average storage modulus and the logarithmic average energy loss modulus of each sample are obtained, so as to quantitatively analyze the change law of viscoelasticity.

2. The method for quantitatively evaluating the viscoelasticity of a polymer solution according to claim 1, characterized in that: Step S1: The method for finding the vibration frequency range when the storage modulus and the loss modulus change regularly is: Find out the critical vibration frequency at which the storage modulus and the energy loss modulus show fluctuations. The data less than or equal to the critical vibration frequency is the required vibration frequency range; data points greater than the critical vibration frequency will not participate in the subsequent calculations.

3. The method for quantitatively evaluating the viscoelasticity of a polymer solution according to claim 1, characterized in that: The viscoelastic frequency scanning experimental data of the sample group in step S1 includes a monitoring array of the change of storage modulus with frequency.

4. The method for quantitatively evaluating the viscoelasticity of a polymer solution according to claim 3, characterized in that: The viscoelastic frequency scanning experimental data of the sample group in step S1 also includes a monitoring array of the change of the energy loss modulus with frequency.

5. The method for quantitatively evaluating the viscoelasticity of a polymer solution according to claim 4, characterized in that: The logarithmic value formula of the storage modulus in step S2 is: i =logG′ i ; Where: A i is the logarithmic value of the storage modulus of the sample at the i-th point within the vibration frequency range with a regular change trend; G' i It is the storage modulus of the sample at the i-th point within the vibration frequency range with a regular change trend.

6. The method for quantitatively evaluating the viscoelasticity of a polymer solution according to claim 5, characterized in that: The formula for the logarithmic value of the energy loss modulus in step S2 is: i =logG" i Where: B i is the logarithmic value of the energy dissipation modulus of the sample at the i-th point within the vibration frequency range with a regular change trend; G” i It is the energy loss modulus of the sample at the i-th point within the vibration frequency range with a regular change trend.

7. The method for quantitatively evaluating the viscoelasticity of a polymer solution according to claim 6, characterized in that: The average formula of the storage modulus logarithm array in step S3 is: Where: is the average of the storage modulus logarithmic array; n is the number of data points of the sample within the vibration frequency range with a regular change trend; A i It is the logarithm of the storage modulus of the sample at the i-th point within the vibration frequency range that shows a regular change trend.

8. The method for quantitatively evaluating the viscoelasticity of a polymer solution according to claim 7, characterized in that: The formula for the average of the energy loss modulus logarithmic array in step S3 is: Where: is the average of the logarithmic array of energy loss modulus; n is the number of data points of the sample within the vibration frequency range with a regular change trend; B i It is the logarithm of the energy dissipation modulus of the sample at the i-th point within the vibration frequency range that shows a regular change trend.

9. The method for quantitatively evaluating the viscoelasticity of a polymer solution according to claim 8, characterized in that: The logarithmic average storage modulus formula of step S4 is: The logarithmic average energy loss modulus formula of step S4 is: Where: A is the logarithmic average storage modulus; B is the logarithmic average energy loss modulus; is the average of the storage modulus logarithmic array; is the average of the energy dissipation modulus logarithmic array.

10. The method for quantitatively evaluating the viscoelasticity of a polymer solution according to claim 1, characterized in that: The method for quantitatively analyzing the change law of viscoelasticity in step S5 is: taking the change factor of the sample group as the vertical coordinate, and the logarithmic average storage modulus and the logarithmic average energy loss modulus as the horizontal coordinate, plotting the change curve of the logarithmic average storage modulus and the logarithmic average energy loss modulus with the change factor; by plotting the change curve, the influence of the change factor on the viscoelasticity of the polymer solution can be intuitively displayed.

Images