A method for detecting the molecular weight and molecular weight distribution of a resin

Abstract

The application provides a method for detecting resin molecular weight and molecular weight distribution, and relates to the field of relative molecular mass determination technology, and comprises the following steps: dissolving and configuring a resin sample solution by using a resin sample; checking whether there is leakage and residual sample in a pipeline and a sample injection system of a GPC device, and adjusting working parameters of the GPC device; starting the GPC device, injecting the resin sample solution after the image is stable, drawing a chromatogram image of the resin sample, and analyzing the accuracy of the chromatogram image of the resin sample; drawing a plurality of chromatogram images of polystyrene with different known molecular weights according to the above steps; drawing a correction curve and a working curve according to the chromatogram image of the polystyrene and the chromatogram image of the resin sample; and calculating the molecular weight and the molecular weight distribution of the resin sample through data analysis. The technical problem that the chromatogram image of the resin material is not checked in the detection process of the existing gel permeation chromatography method, which may cause the chromatogram image used for drawing the working curve to be inaccurate and affect the accuracy of the detection result is solved.

Description

Technical Field

[0001] This invention relates to the field of relative molecular mass determination technology, specifically a method for detecting the molecular weight and molecular weight distribution of resins. Background Technology

[0002] The molecular weight distribution of resins is an important indicator for characterizing polymers, significantly affecting the physical and mechanical properties and molding and processing performance of resin materials. Commonly used determination methods include: viscometry, laser light scattering, mass spectrometry, and size exclusion chromatography (SEC). Among these, gel permeation chromatography (GPC), as a type of size exclusion chromatography, is convenient, fast, and widely available, making it highly applicable.

[0003] Existing gel permeation chromatography methods have the following problems:

[0004] 1. Failure to verify the chromatographic image of the resin material during the testing process may result in inaccurate chromatographic images used for plotting the working curve, affecting the accuracy of the test results;

[0005] 2. The lack of equipment for collecting and treating waste liquid can easily cause environmental pollution. Summary of the Invention

[0006] The present invention provides a method for detecting the molecular weight and molecular weight distribution of resin, thereby solving at least one of the technical problems mentioned above.

[0007] To address the aforementioned technical problems, this invention discloses a method for detecting the molecular weight and molecular weight distribution of resins, comprising:

[0008] Step S1: Dissolve the resin sample to prepare a resin sample solution;

[0009] Step S2: Check the pipelines and sample injection system of the GPC device for leaks and residual samples, and adjust the operating parameters of the GPC device.

[0010] Step S3: Start the GPC device. After the image stabilizes, inject the resin sample solution, plot the chromatographic image of the resin sample, and analyze the accuracy of the chromatographic image of the resin sample.

[0011] Step S4: Following steps S1-S3, draw multiple sets of chromatographic images of polystyrene with different known molecular weights;

[0012] Step S5: Plot the correction curve and working curve based on the chromatographic images of polystyrene and resin samples;

[0013] Step S6: Calculate the molecular weight and molecular weight distribution of the resin sample through data analysis.

[0014] Preferably, step S1 includes:

[0015] Step S11: weigh 40 mg of resin sample, put it into a jar, add 10 ml of tetrahydrofuran solution to dissolve;

[0016] Step S12: after the resin sample is completely dissolved, filter the solution through a 2 μm filter membrane.

[0017] Preferably, step S3 comprises:

[0018] Step S31: divide the resin sample solution into multiple groups of test samples;

[0019] Step S32: use multiple groups of test samples to perform tests in turn, and obtain multiple chromatogram images of the resin sample;

[0020] Step S33: compare the similarity of the multiple chromatogram images in turn, and divide all the chromatogram images into a first group and a second group, the similarity of any two chromatogram images in the first group is greater than a preset first threshold, and the rest of the chromatogram images are placed in the second group;

[0021] Step S34: calculate a first ratio of the number of chromatogram images in the first group to the number of chromatogram images of all resin samples, and determine whether the first ratio is greater than a preset second threshold, if the first ratio is greater than the preset second threshold, use the chromatogram images in the first group to draw the working curve, if the first ratio is less than or equal to the preset second threshold, re-prepare the resin sample solution and repeat steps S31-S33.

[0022] Preferably, step S5 comprises:

[0023] Step S51: measure the retention volume corresponding to the sample peak in the chromatogram image of each different molecular weight polystyrene;

[0024] Step S52: draw a correction curve on a semilog coordinate system with the retention volume of polystyrene as the abscissa and the molecular weight of polystyrene as the ordinate;

[0025] Step S53: take several molecular weights of polystyrene on the correction curve, and calculate the molecular weight of the resin sample by Formula One;

[0026] Step S54: draw a working curve on a semilog coordinate system with the retention volume of the resin sample as the abscissa and the molecular weight of the resin sample calculated in step S53 as the ordinate;

[0027] Step S55: obtain a working curve equation according to the working curve.

[0028] Preferably, step S6 comprises:

[0029] Step S61: mark the sample peak on the chromatogram image point and point, point is the point at which the sample peak just lifts off the baseline, point is the point at which the sample peak returns to the baseline;

[0030] Step S62: The chromatogram of the resin sample is divided into several equal slices by a straight line perpendicular to the baseline, and the retention volume, peak height, area and molecular weight of each equal slice are recorded, the molecular weight is obtained by bringing the retention volume of each point into the working curve equation;

[0031] Step S63: The molecular weight distribution width index is calculated by Formula Two.

[0032] Preferably, Formula One is:

[0033] ;

[0034] Wherein: is a constant related to temperature in the viscosity coefficient of polystyrene; is a constant related to temperature in the viscosity coefficient of the resin sample; is a characteristic constant related to the polymer system in the viscosity coefficient of polystyrene; is a characteristic constant related to the polymer system in the viscosity coefficient of the resin sample; is the molecular weight of polystyrene; is the molecular weight of the resin sample; is the logarithmic function with base 10;

[0035] Formula Two is:

[0036] ;

[0037] Wherein: D is the molecular weight distribution width index; is the peak area of the i-th equal slice; is the molecular weight of the i-th equal slice; T is the total number of equal slices.

[0038] Preferably, the GPC device comprises a solvent tank for storing filtered tetrahydrofuran, the solvent tank is in communication with the liquid inlet of a high-pressure flow pump, the liquid outlet of the high-pressure flow pump is connected with a sample injector, the liquid outlet of the sample injector is in communication with the liquid inlet of a chromatographic column, the liquid outlet of the chromatographic column is connected with a differential detector, the liquid outlet of the differential detector is connected with a waste liquid treatment tank, and the liquid outlet of the waste liquid treatment tank is connected with a waste liquid collection tank.

[0039] Preferably, the waste liquid treatment box comprises a box body, a liquid inlet is arranged at the upper end of the left side wall of the box body, a liquid outlet is arranged at the lower end of the right side wall of the box body, the liquid outlet is provided with an electric valve, an oxide storage box and a gas purification box are connected to the upper surface of the box body, an oxidizing agent is stored in the oxide storage box, a horizontal plate is fixedly connected to the inner wall of the oxide storage box, an electric control gate is arranged on the horizontal plate, a waste tank is fixedly connected to the left side wall of the box body, a viewing window is arranged on the outer wall of the waste tank, a filter plate is fixedly connected to the inner wall of the waste tank, the waste tank is communicated with the inside of the box body through a waste port and a reflux port, the reflux port is arranged below the filter plate, a collection tank is fixedly connected to the inner wall of the box body at the waste port, center rods are fixedly connected to the inner walls of the front and rear sides of the box body, a bearing tank is rotatably sleeved on the center rods, a limiting plate is fixedly connected to the right side inner wall of the box body, and the upper surface of the limiting plate is in contact with the right side of the lower bottom surface of the bearing tank.

[0040] Preferably, a T-shaped seat is fixedly connected to the inner top surface of the box body, a floating plate is sleeved on the T-shaped seat, the right side lower surface of the floating plate is connected to the right part of the bearing tank through a connecting rope one, two limiting blocks are symmetrically and slidably connected to the left and right side walls of the vertical part of the T-shaped seat, a conical surface is arranged on each limiting block, a spring one is fixedly connected between the two limiting blocks, a connecting rod is hinged to one end of the two limiting blocks, the other end of the connecting rod is hinged to the center plate, the upper surface of the center plate is connected to a control assembly, a connecting plate is fixedly connected to the inner top surface of the box body, a discharging plate is slidably connected to the inner top surface of the box body in the left-right direction, a discharging hole is arranged on the discharging plate, a spring two is fixedly connected between the left end of the discharging plate and the right side wall of the connecting plate, a connecting rope three is fixedly connected to the right end of the discharging plate, and the other end of the connecting rope three is fixedly connected to the upper surface of the center plate after passing around a steering wheel.

[0041] Preferably, the control assembly comprises a limiting box, the limiting box is fixedly connected to the right side wall of the box body, a communication hole is arranged on the bottom surface of the limiting box, a floating block is arranged in the limiting box, a supporting rod is fixedly connected to the upper surface of the floating block, the supporting rod is slidably penetrated through the upper wall of the limiting box in the up-down direction, a counterweight is fixedly connected to the upper end of the supporting rod, a connecting rope two is fixedly connected to the upper surface of the counterweight, and the other end of the connecting rope two is fixedly connected to the upper surface of the center plate after passing around a steering wheel.

[0042] The technical solutions of the present application are described in further detail below with reference to the drawings and examples.

[0043] Compared with the prior art, the present application has the following beneficial effects:

[0044] By dividing the prepared resin sample solution into multiple groups of test samples, multiple chromatogram images of the resin samples are obtained, and by comparing the multiple chromatogram images of the resin samples, the similarity between the chromatogram images of the resin samples exceeding the second threshold value is ensured to be greater than the first threshold value, thereby ensuring the accuracy of the chromatogram images and effectively improving the accuracy of the resin molecular weight and molecular weight distribution results. BRIEF DESCRIPTION OF DRAWINGS

[0045] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and are meant to explain the application and are not intended to limit the application. In the drawings:

[0046] Figure 1 Flow chart of the method of the present application;

[0047] Figure 2 Structure diagram of the GPC device of the present application;

[0048] Figure 3 Structure diagram of the waste liquid treatment tank of the present application;

[0049] Figure 4 Structure diagram of the A area in Figure 3

[0050] In the figure: 1, solvent tank; 2, high-pressure flow pump; 3, sample injector; 4, chromatographic column; 5, differential detector; 6, waste liquid treatment tank; 7, waste liquid collection tank; 8, tank body; 9, electric valve; 10, oxide storage tank; 11, gas purification tank; 12, cross plate; 13, electric control gate; 14, waste tank; 15, viewing window; 16, filter plate; 17, waste port; 18, reflux port; 19, collection tank; 20, center rod; 21, bearing tank; 22, limiting plate; 23, T-shaped seat; 24, floating plate; 25, connecting rope one; 26, limiting block; 27, conical surface; 28, spring one; 29, connecting rod; 30, center plate; 31, connecting plate; 32, discharge plate; 33, spring two; 34, connecting rope three; 35, steering wheel; 36, limiting tank; 37, communication hole; 38, floating block; 39, support rod; 40, counterweight; 41, connecting rope two. DETAILED DESCRIPTION

[0051] The preferred embodiments of the present application will be described herein below with reference to the drawings, and it should be understood that the preferred embodiments described herein are intended for explaining and illustrating the present application, and are not intended to limit the present application.

[0052] ​In addition, the description such as "first", "second" and the like in the present application is only for the purpose of description and does not mean to particularly indicate the order or sequence, nor to limit the present application, which is merely to distinguish the components or operations described by the same technical terms, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implying the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions and technical features of various embodiments can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0053] The present application provides the following embodiments

[0054] Embodiment 1

[0055] The present application provides a method for detecting the molecular weight and molecular weight distribution of resin, comprising:

[0056] Step S1: dissolve the resin sample to prepare a resin sample solution;

[0057] Step S2: check whether there is leakage and residual sample in the pipeline and sample injection system of the GPC device, and adjust the working parameters of the GPC device;

[0058] Step S3: start the GPC device, inject the resin sample solution after the image is stable, draw the chromatogram image of the resin sample, and analyze the accuracy of the chromatogram image of the resin sample;

[0059] Step S4: draw the chromatogram image of a plurality of groups of polystyrene with different known molecular weights according to the steps of steps S1-S3;

[0060] Step S5: draw the correction curve and the working curve according to the chromatogram image of polystyrene and the chromatogram image of the resin sample;

[0061] Step S6: calculate the molecular weight and molecular weight distribution of the resin sample through data analysis.

[0062] Preferably, step S1 comprises:

[0063] Step S11: weigh 40mg of resin sample, put it into a wide-mouth bottle, and add 10ml of tetrahydrofuran solution for dissolution;

[0064] Step S12: filter the solution through a 2μm filter membrane after the resin sample is completely dissolved.

[0065] Preferably, step S3 comprises:

[0066] Step S31: divide the resin sample solution into multiple groups of test samples;

[0067] Step S32: sequentially perform tests using the multiple groups of test samples to obtain chromatographic images of the multiple resin samples;

[0068] Step S33: sequentially compare the similarity of the chromatographic images of the multiple resin samples, and divide all the chromatographic images into a first group and a second group, wherein the similarity of any two chromatographic images in the first group is greater than a preset first threshold, and the rest of the chromatographic images are placed in the second group;

[0069] Step S34: calculate a first ratio of the number of chromatographic images in the first group to the number of chromatographic images of all resin samples, and determine whether the first ratio is greater than a preset second threshold, if the first ratio is greater than the preset second threshold, use the chromatographic images in the first group to draw a working curve, if the first ratio is less than or equal to the preset second threshold, re-prepare the resin sample solution and repeat steps S31-S33.

[0070] Preferably, step S5 comprises:

[0071] Step S51: measure the retention volume corresponding to the sample peak in the chromatographic image of each different molecular weight polystyrene;

[0072] Step S52: draw a correction curve on a semilog coordinate system with the retention volume of polystyrene as the abscissa and the molecular weight of polystyrene as the ordinate;

[0073] Step S53: take several molecular weights of polystyrene on the correction curve, and calculate the molecular weight of the resin sample by Formula One;

[0074] Step S54: draw a working curve on a semilog coordinate system with the retention volume of the resin sample as the abscissa and the molecular weight of the resin sample calculated in step S53 as the ordinate;

[0075] Step S55: obtain a working curve equation according to the working curve.

[0076] Preferably, step S6 comprises:

[0077] Step S61: mark the points of , , on the chromatographic image, wherein the point of is the point at which the sample peak just rises, and the point of is the point at which the sample peak returns to the baseline;

[0078] Step S62: the chromatogram of the resin sample is divided into several equal parts by a straight line perpendicular to the baseline, the retention volume, peak height, area and molecular weight of each equal part are recorded, and the molecular weight is obtained by bringing the retention volume of each point into the working curve equation;

[0079] Step S63: the distribution width index of the molecular weight is calculated by Formula Two.

[0080] Preferably, Formula One is:

[0081] ;

[0082] Wherein: is a constant related to temperature in the viscosity coefficient of polystyrene; is a constant related to temperature in the viscosity coefficient of the resin sample; is a characteristic constant related to the polymer system in the viscosity coefficient of polystyrene; is a characteristic constant related to the polymer system in the viscosity coefficient of the resin sample; is the molecular weight of polystyrene; is the molecular weight of the resin sample; is the logarithmic function with base 10;

[0083] Formula Two is:

[0084] ;

[0085] Wherein: D is the molecular weight distribution width index; is the peak area of the i-th equal part; is the molecular weight of the i-th equal part; T is the total number of equal parts.

[0086] Wherein, optionally, the reliability P of the molecular weight calculation is calculated based on Formula Three, and when the reliability is less than a corresponding preset value, a warning is given;

[0087] ;

[0088] is the first ratio, is the ratio of the number of chromatograms in the second group to the number of chromatograms of all resin samples; is the average value of the similarity of any two chromatograms in the first group; is the maximum value of the similarity of any two chromatograms in the first group; is the minimum value of the similarity of any two chromatograms in the first group; is the average value of the similarity of the k-th chromatogram in the second group and all chromatograms in the first group; F is the total number of chromatograms in the second group; The minimum function.

[0089] Preferably, the GPC device comprises a solvent tank 1 for storing filtered tetrahydrofuran, the solvent tank 1 being in communication with a liquid inlet of a high-pressure flow pump 2, a liquid outlet of the high-pressure flow pump 2 being connected with a sample injector 3, a liquid outlet of the sample injector 3 being in communication with a liquid inlet of a chromatographic column 4, a liquid outlet of the chromatographic column 4 being connected with a differential detector 5, a liquid outlet of the differential detector 5 being connected with a waste liquid treatment tank 6, and a liquid outlet of the waste liquid treatment tank 6 being connected with a waste liquid collection tank 7.

[0090] In this embodiment, each group of test samples is tested separately, and the recorder completely draws the chromatogram of the previous group of test samples before injecting the next group of test samples.

[0091] In this embodiment, the working parameters of the GPC device include the sensitivity of the instrument, the type of detector, the polarity, the pump flow rate, and the sample injection volume.

[0092] In this embodiment, the calibration curve is a curve drawn using the chromatogram of polystyrene with a known molecular weight.

[0093] In this embodiment, the working curve is a curve used to calculate the molecular weight of the resin, which is drawn based on the calibration curve and the chromatogram of the resin sample.

[0094] In this embodiment, the reason for filtering the dissolved resin sample solution is that the solution detected by gel permeation chromatography cannot contain solid components to avoid affecting the test results and prevent damage to the instrument.

[0095] In this embodiment, when analyzing the similarity of the chromatograms, the sample peaks in the chromatograms are intercepted, the points where the sample peaks rise are overlapped, and then the similarity of the sample peaks in the two chromatograms is analyzed. The similarity of the sample peaks is the similarity of the chromatograms. In addition to the similarity analysis of the first group of chromatograms, the two chromatograms used for similarity analysis of all subsequent chromatograms come from the first group and the unanalyzed group. The unanalyzed group is the group where the chromatogram similarity analysis has not been performed.

[0096] In this embodiment, the retention volume refers to the volume of mobile phase consumed from the start of sample injection to the point where the concentration of the measured component reaches a maximum after the column.

[0097] In this embodiment, the baseline is a horizontal straight line, which is a measurement reference and one of the indicators for checking whether the instrument is working properly.

[0098] In this embodiment, the vertical distance from the highest point of the sample peak to the baseline is called the peak height.

[0099] In this embodiment, the area of the sample peak is the area of the image composed of the sample peak and the baseline.

[0100] In this embodiment, the distribution width index is an index used to represent the dispersion degree of the molecular weight distribution.

[0101] The technical scheme has the following beneficial effects:

[0102] By dividing the prepared resin sample solution into multiple groups of test samples, multiple chromatograms of the resin samples are obtained, and by comparing the multiple chromatograms of the resin samples, it is ensured that the first ratio of a first group with a similarity greater than a first threshold value is greater than a second threshold value, thereby ensuring the accuracy of the chromatogram and effectively improving the accuracy of the molecular weight and molecular weight distribution of the resin.

[0103] Embodiment 2

[0104] On the basis of embodiment 1, the waste liquid treatment tank 6 comprises a tank body 8, a liquid inlet is arranged at the upper end of the left side wall of the tank body 8, a liquid outlet is arranged at the lower end of the right side wall of the tank body 8, the liquid outlet is provided with an electric valve 9, an oxide storage tank 10 and a gas purification tank 11 are connected to the upper surface of the tank body 8, an oxidizing agent is stored in the oxide storage tank 10, a horizontal plate 12 is fixedly connected to the inner wall of the oxide storage tank 10, an electrically controlled gate 13 is arranged on the horizontal plate 12, a waste tank 14 is fixedly connected to the left side wall of the tank body 8, a viewing window 15 is arranged on the outer wall of the waste tank 14, a filter plate 16 is fixedly connected to the inner wall of the waste tank 14, the waste tank 14 is in communication with the inside of the tank body 8 through a waste port 17 and a reflux port 18, the reflux port 18 is arranged on the lower side of the filter plate 16, a collection tank 19 is fixedly connected to the waste port 17 of the inner wall of the tank body 8, a center rod 20 is fixedly connected to the inner walls of the front and rear sides of the tank body 8, a bearing tank 21 is rotatably sleeved on the center rod 20, a limiting plate 22 is fixedly connected to the right side inner wall of the tank body 8, and the upper surface of the limiting plate 22 is in contact with the lower bottom surface right side of the bearing tank 21.

[0105] Preferably, a T-shaped seat 23 is fixedly connected to the inner top surface of the tank body 8, a floating plate 24 is sleeved on the T-shaped seat 23, the right lower surface of the floating plate 24 is connected to the right part of the bearing tank 21 through a connecting rope one 25, two limiting blocks 26 are symmetrically and slidably connected to the left and right side walls of the vertical part of the T-shaped seat 23, a conical surface 27 is arranged on the limiting block 26, a spring one 28 is fixedly connected between the two limiting blocks 26, a connecting rod 29 is hinged to one end of the two limiting blocks 26, the other end of the connecting rod 29 is hinged to a center plate 30, the upper surface of the center plate 30 is connected to a control assembly, a connecting plate 31 is fixedly connected to the inner top surface of the tank body 8, a discharging plate 32 is slidably connected to the inner top surface of the tank body 8 along the left-right direction, a discharging hole is arranged on the discharging plate 32, a spring two 33 is fixedly connected between the left end of the discharging plate 32 and the right side wall of the connecting plate 31, a connecting rope three 34 is fixedly connected to the other end of the center plate 30 after passing through a steering wheel 35.

[0106] Preferably, the control assembly comprises a limiting box 36 fixedly connected to the right side wall of the box body 8, the bottom surface of the limiting box 36 is provided with a communication hole 37, a floating block 38 is placed in the limiting box 36, the upper surface of the floating block 38 is fixedly connected with a support rod 39, the support rod 39 is slidably penetrated through the upper wall of the limiting box 36 in the up-down direction, the upper end of the support rod 39 is fixedly connected with a counterweight 40, the upper surface of the counterweight 40 is fixedly connected with a connecting rope two 41, the other end of the connecting rope two 41 is fixedly connected to the upper surface of the center plate 30 after being wound around the steering wheel 35.

[0107] The beneficial effects of the above technical solution are:

[0108] The test completed tetrahydrofuran flows into the box body 8 through the liquid inlet, when the tetrahydrofuran accumulates to a certain liquid level, the tetrahydrofuran reacts with the oxide carried on the carrying groove 21, so that the tetrahydrofuran reacts with the oxide, thereby reducing the concentration of tetrahydrofuran in the waste liquid, avoiding the volatilization of tetrahydrofuran into the air to affect the health of the experimental personnel, and further preventing the tetrahydrofuran gas from entering the experimental space to affect the health of the experimental personnel by setting the gas purification box 11 to absorb the volatilized tetrahydrofuran gas. As the liquid level of the waste liquid continues to rise, the floating plate 24 is lifted under the action of the buoyancy until the floating plate 24 moves to above the limiting block 26, the right part of the carrying groove 21 is lifted through the connecting rope one 25, so that the oxide on the carrying groove 21 falls into the collecting groove 19 along the carrying groove 21, and finally falls into the waste liquid tank 14. At the same time, the electric valve 9 is opened, so that the treated waste liquid in the waste liquid treatment box 6 flows into the waste liquid collecting tank 7 for storage. As the waste liquid flows out, the liquid level of the waste liquid drops, so that the floating block 38 also falls, under the action of the counterweight 40, the connecting rope two 41 is pulled, the center plate 30 moves upward, the two limiting blocks 26 are close to each other, the floating plate 24 loses the limit and falls below the limiting block 26, and the connecting rope three 34 no longer exerts a pulling force on the discharge plate 32. The discharge plate 32 moves left under the action of the spring two 33, so that the discharge hole on the discharge plate 32 is in communication with the discharge port of the oxide storage tank 10, so that the oxide below the partition plate falls from the discharge port to the carrying groove 21, completing the replacement of the oxide. After the waste liquid is completely discharged, the electric valve 9 is closed, as the liquid level of the waste liquid rises again, the floating block 38 rises under the action of the buoyancy, the center plate 30 loses the pulling force of the connecting rope two 41 and moves downward under the action of the spring one 28 to return to the initial position, and the electric control gate 13 is started. The oxide above the partition plate is quantitatively dropped below the partition plate, ready for the replacement of the next oxide.

[0109] The regular replacement of the oxidant ensures the purification effect of the waste liquid, the waste height in the waste tank 14 can be conveniently observed through the sight window 15, the experimental personnel can clean the waste oxidant in time, the lower part of the waste tank 14 is provided with a reflux port 18 in communication with the inside of the box body 8, so that the oxidant in the waste tank 14 can still participate in the reaction, the utilization rate of the oxidant is improved, the oxidant storage tank 10 is divided into two parts by the partition plate, the volatilized tetrahydrofuran gas is prevented from reacting with all the oxidants, the quality of all the oxidants is affected, the quantitative feeding of the oxidant is completed through the electric control gate 13, the accurate amount of the oxidant is ensured, the waste of the oxidant is avoided while the purification effect is ensured, the falling of the floating plate 24 is limited through the limiting block 26 before the waste liquid flows out, the replacement of the oxidant is more thorough, the accumulation of too much oxidant on the bearing tank 21 is prevented, the flowability of the bearing tank 21 is ensured, the automatic resetting of the device is completed after the waste liquid flows out, the operation of the experimental personnel to open the waste liquid treatment box 6 is reduced, the volatilization amount of tetrahydrofuran into the external environment is reduced, the health of the experimental personnel is ensured, and the service life of the waste liquid treatment box 6 is improved.

[0110] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A method for detecting the molecular weight and molecular weight distribution of a resin, characterized by: The method comprises the following steps: Step S1: dissolving the resin sample to prepare a resin sample solution; Step S2: checking the pipeline and sample injection system of the GPC device for leakage and residual sample, and adjusting the working parameters of the GPC device; Step S3: starting the GPC device, injecting the resin sample solution after the image is stable, drawing a chromatogram of the resin sample, and analyzing the accuracy of the chromatogram of the resin sample; The step S3 comprises the following steps: Step S31: dividing the resin sample solution into multiple groups of test samples; Step S32: sequentially performing tests by using the multiple groups of test samples to obtain multiple chromatograms of the resin sample; Step S33: sequentially comparing the similarity of the multiple chromatograms of the resin sample, and dividing all the chromatograms into a first group and a second group, the similarity of any two chromatograms in the first group is greater than a preset first threshold, and the rest of the chromatograms are placed in the second group; Step S34: calculating a first ratio of the number of chromatograms in the first group to the number of chromatograms of all resin samples, and judging whether the first ratio is greater than a preset second threshold, if the first ratio is greater than the preset second threshold, using the chromatograms in the first group to draw a working curve, and if the first ratio is less than or equal to the preset second threshold, repeating the steps of Step S31 to Step S33 after preparing the resin sample solution again; Step S4: drawing chromatograms of multiple groups of polystyrene with different known molecular weights according to the steps of Step S1 to Step S3; Step S5: drawing a correction curve and a working curve according to the chromatograms of the polystyrene and the chromatogram of the resin sample; Step S6: calculating the molecular weight and the molecular weight distribution of the resin sample through data analysis.

2. The method for detecting the molecular weight and molecular weight distribution of resin according to claim 1, characterized in that: The step S1 comprises the following steps: Step S11: weighing 40 mg of the resin sample, placing the resin sample into a wide-mouth bottle, and adding 10 ml of tetrahydrofuran solution to dissolve the resin sample; Step S12: filtering the solution through a 2 μm filter membrane after the resin sample is completely dissolved.

3. The method for detecting the molecular weight and molecular weight distribution of resin according to claim 1, characterized in that: The step S5 comprises the following steps: Step S51: measuring the retention volume corresponding to the sample peak in each chromatogram of the polystyrene with different molecular weights; Step S52: taking the retention volume of the polystyrene as the abscissa and the molecular weight of the polystyrene as the ordinate to draw a correction curve on a semilog coordinate system; Step S53: taking a plurality of molecular weights of the polystyrene on the correction curve, and calculating the molecular weight of the resin sample through a formula one; Step S54: taking the retention volume of the resin sample as the abscissa and the molecular weight of the resin sample calculated in Step S53 as the ordinate to draw a working curve on a semilog coordinate system; Step S55: obtaining a working curve equation according to the working curve.

4. The method for detecting the molecular weight and molecular weight distribution of resin according to claim 3, characterized in that: The step S6 comprises the following steps: Step S61: Labeling on the chromatogram image the point and the point, the point is the point at which the sample peak just lifts off, the point is the point at which the sample peak returns to the baseline; Step S62: dividing the chromatogram of the resin sample into a plurality of equal parts by a straight line perpendicular to the baseline, recording the retention volume, peak height, area and molecular weight of each equal part, and obtaining the molecular weight by inputting the retention volume of each point into the working curve equation; Step S63: calculating the molecular weight distribution width index through a formula two.

5. The method according to claim 4, wherein the formula one is: and the formula two is: ​ ； wherein: is a temperature dependent constant in the polystyrene viscosity coefficient; is a temperature dependent constant in the resin sample viscosity coefficient; is a characteristic constant related to the polymer system in the polystyrene viscosity coefficient; is a characteristic constant related to the polymer system in the resin sample viscosity coefficient; is the molecular weight of polystyrene; is the molecular weight of the resin sample; is the logarithm function with base 10; ​ ； wherein: D is the molecular weight distribution breadth index; is the peak area of the ith fraction; is the molecular weight of the ith fraction; and T is the total number of fractions.

6. The method for detecting the molecular weight and molecular weight distribution of resin according to claim 1, characterized in that: The GPC device comprises a solvent tank (1) for storing filtered tetrahydrofuran, a high-pressure flow pump (2) connected to the solvent tank (1), a sample injector (3) connected to the high-pressure flow pump (2), a chromatographic column (4) connected to the sample injector (3), a differential detector (5) connected to the chromatographic column (4), a waste liquid treatment tank (6) connected to the differential detector (5), and a waste liquid collection tank (7) connected to the waste liquid treatment tank (6).

7. The method of claim 6, wherein the resin is a polyethylene resin. The waste liquid treatment tank (6) comprises a tank body (8), a liquid inlet provided on the upper end of the left side wall of the tank body (8), a liquid outlet provided on the lower end of the right side wall of the tank body (8), an electric valve (9) arranged on the liquid outlet, an oxide storage tank (10) and a gas purification tank (11) connected to the upper surface of the tank body (8), an oxidizing agent stored in the oxide storage tank (10), a horizontal plate (12) fixedly connected to the inner wall of the oxide storage tank (10), an electric control gate (13) arranged on the horizontal plate (12), a waste tank (14) fixedly connected to the left side wall of the tank body (8), a viewing window (15) arranged on the outer wall of the waste tank (14), a filter plate (16) fixedly connected to the inner wall of the waste tank (14), the waste tank (14) being in communication with the inside of the tank body (8) through a waste port (17) and a reflux port (18), the reflux port (18) being arranged below the filter plate (16), a collection tank (19) fixedly connected to the inner wall of the tank body (8) at the waste port (17), a center rod (20) fixedly connected to the inner walls of the front and rear sides of the tank body (8), a bearing tank (21) rotatably sleeved on the center rod (20), a limiting plate (22) fixedly connected to the right side inner wall of the tank body (8), and the upper surface of the limiting plate (22) being in contact with the lower bottom surface right side of the bearing tank (21).

8. The method for detecting the molecular weight and molecular weight distribution of resin according to claim 7, characterized in that: A T-shaped seat (23) is fixedly connected to the inner top surface of the tank body (8), a floating plate (24) is sleeved on the T-shaped seat (23), the right lower surface of the floating plate (24) is connected to the right part of the bearing tank (21) through a connecting rope I (25), two limiting blocks (26) are symmetrically and slidably connected to the left and right side walls of the vertical part of the T-shaped seat (23), a conical surface (27) is arranged on the limiting block (26), a spring I (28) is fixedly connected between the two limiting blocks (26), a connecting rod (29) is hinged to one end of the two limiting blocks (26) which are close to each other, the other end of the connecting rod (29) is hinged to a center plate (30), the upper surface of the center plate (30) is connected to a control assembly, a connecting plate (31) is fixedly connected to the inner top surface of the tank body (8), a discharging plate (32) is slidably connected to the inner top surface of the tank body (8) along the left-right direction, a discharging hole is arranged on the discharging plate (32), a spring II (33) is fixedly connected between the left end of the discharging plate (32) and the right side wall of the connecting plate (31), a connecting rope III (34) is fixedly connected to the right end of the discharging plate (32), and the other end of the connecting rope III (34) is fixedly connected to the upper surface of the center plate (30) after passing through a steering wheel (35).

9. The method of claim 8, wherein the resin is a polyethylene resin. The control assembly comprises a limiting box (36) fixedly connected to the right side wall of the box body (8), the bottom surface of the limiting box (36) is provided with a communication hole (37), the limiting box (36) is placed with a floating block (38), the upper surface of the floating block (38) is fixedly connected with a supporting rod (39), the supporting rod (39) is slidably penetrated through the upper wall of the limiting box (36) in the up-down direction, the upper end of the supporting rod (39) is fixedly connected with a counterweight (40), the upper surface of the counterweight (40) is fixedly connected with a connecting rope two (41), the other end of the connecting rope two (41) is fixedly connected to the upper surface of the center plate (30) after being wound around the steering wheel (35).

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