A device and method for preparing test samples for time domain nuclear magnetic resonance analyzer

Abstract

The present application discloses a preparation device for a time domain nuclear magnetic resonance analyzer test sample, the device including a hollow cylindrical sample chamber for filling a sample, and also including: a bolt seal, located at one end of the sample chamber and threadedly connected to the sample chamber; a screw, extending into the other end of the sample chamber, the outer wall of the screw being threadedly sealed with the inner wall of the sample chamber; a heating chamber, sleeved on the periphery of the sample chamber, and slidingly arranged with the sample chamber for heating and melting the sample in the sample chamber; a cooling chamber, with a built-in 0-4°C ice-water mixture, after the sample is heated and melted, the sample chamber is placed in the cooling chamber for crystallizing the sample; wherein the sample is located between the end of the screw and the bolt seal, and the inner wall of the sample chamber corresponding to the sample is a smooth cylindrical surface. The preparation device arranged in the above manner can avoid the influence of external air on sample preparation, while avoiding the preparation error caused by "thermal cracking" or "Coanda effect", thereby improving time test accuracy.

Description

Technical Field

[0001] The present application relates to the field of sample preparation technology, and in particular to a sample preparation device for a time-domain nuclear magnetic resonance analyzer. In addition, the present application also relates to a preparation method implemented using the above-mentioned preparation device. Background Art

[0002] Time-domain NMR technology uses a permanent magnetic field and radio frequency energy to illuminate atomic nuclei sensitive to NMR, such as hydrogen and fluorine, causing them to generate radio frequency signals that can then be detected. The amplitude and duration of these signals are related to the sample's properties.

[0003] Since the discovery of nuclear magnetic resonance signals of condensed matter in the 1950s, nuclear magnetic resonance theory and analysis methods have developed rapidly and have become a powerful tool for studying a series of problems in physics, chemistry and life sciences. As an independent branch, low-field solid-state nuclear magnetic resonance (LF-NMR) has the advantages of low cost, low maintenance and short cycle time, and is mainly used in industrial standard relaxation measurement applications. This technology can measure the proton dipole coupling strength, which is an effective basis for judging the speed of molecular chain dynamics in polymers. Combined with the difference in the activity ability of molecular chains between different phases of semi-crystalline polymers, it can achieve quantitative characterization of characteristic structural information such as chain conformation, phase composition and morphology of polymers. Minispec time-domain nuclear magnetic resonance analyzer (a series of time-domain nuclear magnetic resonance analyzer models affiliated to the German Bruker brand company) is a mature industrial low-field nuclear magnetic resonance spectrometer with the advantages of being fast, non-destructive and solvent-free. Based on the high sensitivity of nuclear magnetic resonance spectrometers, there are often high requirements for samples. Usually, samples with a height of about 12 mm are prepared in a nuclear magnetic resonance tube with an outer diameter of 10 mm, as shown in the attached instruction manual. Figure 1 As shown, this ensures that the test sample is in the most uniform RF field position of the spectrometer.

[0004] The main existing method for preparing test samples for the Minispec time-domain NMR analyzer involves calculating the mass of a sample of corresponding size using density calculations, weighing that mass, and placing it into an NMR tube (1). A quenching process is then used to manipulate the polymer's crystal structure. During the quenching process, the sample in the NMR tube (1) is first heated to a temperature above the melting point of 30°C, fully melted for a period of time until it is completely relaxed, and then rapidly cooled at a rate exceeding the critical cooling rate. A common cooling medium is an ice-water mixture at 0-4°C. Large temperature differences between ambient temperatures can cause non-uniform shrinkage of the NMR tube (1), generating significant thermal stress and subsequent "thermal cracking." Even if thermal cracking does not occur, the prepared cylindrical sample inside the tube can still generate bubbles and the "Coanda effect" (wall adhesion effect) during the sudden cooling process due to a lack of external pressure, especially for systems with high melt viscosity, such as polybutene-1. Both of these factors can affect sample preparation and result in significant test errors for the analyzer. In addition, during the process of preparing samples using the nuclear magnetic resonance tube 1, a large number of protons in the water vapor in the air will affect the experimental results and also cause test errors of the analyzer.

[0005] Therefore, in view of the above technical problems, how to design and improve the test accuracy of the time domain nuclear magnetic resonance analyzer for the test sample is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this application is to provide a preparation device for test samples of a time-domain nuclear magnetic resonance analyzer, which can avoid the influence of external air on sample preparation, and at the same time avoid preparation errors caused by "thermal cracking" or "Coanda effect", thereby improving the test accuracy of the time-domain nuclear magnetic resonance analyzer on the test samples.

[0007] Another object of the present application is to provide a preparation method implemented using the above-mentioned preparation device, wherein the sample prepared by this method is a uniform spline of the size required for testing by the Minisipec time-domain nuclear magnetic resonance analyzer, thereby ensuring the test accuracy of the test sample by the domain nuclear magnetic resonance analyzer.

[0008] To achieve the above-mentioned objectives, the present application provides a device for preparing test samples for a time-domain nuclear magnetic resonance analyzer, comprising a hollow cylindrical sample chamber for filling the sample, and further comprising:

[0009] A bolt seal is located at one end of the sample cavity and is threadedly connected to the sample cavity;

[0010] A screw rod extends into the other end of the sample chamber, and the outer wall of the screw rod is threadedly and sealedly connected to the inner wall of the sample chamber;

[0011] A heating chamber is sleeved on the periphery of the sample chamber and is slidably arranged with the sample chamber, and is used to heat and melt the sample in the sample chamber;

[0012] A cooling chamber is provided with a 0-4°C ice-water mixture. After the sample is heated and melted, the sample chamber is placed in the cooling chamber to crystallize the sample.

[0013] The sample is located between the end of the screw and the bolt seal, and the inner wall of the sample cavity corresponding to the sample is a smooth cylindrical surface.

[0014] Preferably, an internal thread is provided on the inner wall of the sample cavity corresponding to the bolt seal, and the minor diameter of the internal thread is larger than the inner diameter of the sample cavity.

[0015] Preferably, the sample chamber and the heating chamber are made of heat-conductive and high-temperature-resistant 45# steel, the heating chamber has a built-in electric heater, and the electric heater is externally connected to a temperature control box.

[0016] Preferably, the heating chamber is further provided with a thermocouple for detecting the temperature thereof, and the thermocouple is externally connected to the temperature control box.

[0017] Preferably, the device for preparing a time domain nuclear magnetic resonance analyzer test sample further comprises:

[0018] A fixed bottom plate, on the end surface of which the heating chamber and the cooling chamber are fixedly arranged;

[0019] a fixed top plate, fixedly connected to the fixed bottom plate via a fixing column, wherein the heating chamber and the cooling chamber are both located between the fixed bottom plate and the fixed bottom plate, and are spaced apart from the fixed top plate;

[0020] Wherein, through holes corresponding to the positions of the heating cavity and the cooling cavity are respectively provided on the fixed top plate, and the sample cavity passes through the through holes and is placed in the heating cavity or the cooling cavity.

[0021] Preferably, the end of the sample cavity away from the bolt seal is provided with a limit seal that is engaged with it, the inner wall of the limit seal is threadedly connected to the outer wall of the sample cavity, the screw passes through the limit seal and extends into the sample cavity, and the screw moves axially relative to the limit seal.

[0022] Preferably, the outer diameter of the position-limiting seal is larger than the outer diameter of the sample cavity and is located in the through hole. The outer wall of the position-limiting seal abuts against the inner wall of the through hole to limit the shaking of the sample cavity and the screw in the through hole.

[0023] Preferably, the fixed bottom plate, the fixed top plate and the cooling chamber are made of POM material.

[0024] In addition, the present application also provides a preparation method implemented by the preparation device for preparing a test sample using a time-domain nuclear magnetic resonance analyzer as described in any of the above items, the method comprising the following steps:

[0025] Step a, obtaining the mass of the sample of corresponding volume by density calculation, and adding the sample into the sample cavity;

[0026] Step b, extending the sample cavity into the heating cavity, and ensuring that the corresponding range of the sample is within the heating cavity;

[0027] Step c, heating the heating chamber to above 30° C., and uniformly melting the sample;

[0028] Step d, rotating the screw to provide pressure for the molten sample, reducing the flow space of the melt, and at the same time exhausting the air in the cavity through the bolt seal;

[0029] Step e: until the molten sample overflows from the bolt seal, stop rotating the screw and stop heating;

[0030] Step f: placing the sample cavity into the cooling cavity, allowing the molten sample to crystallize quickly to form a glue seal, while simultaneously rapidly rotating the screw to provide pressure to expel the crystals.

[0031] Compared to the above-mentioned background technology, the sample chamber of the present application is provided with a bolt seal and a screw at each end. The bolt seal is threadedly connected to the sample chamber, which has a certain sealing effect, but it cannot be completely sealed. Therefore, under the pressure of the rotating screw, the gas in the sample chamber will be discharged from the sample chamber through the bolt seal. Specifically, when the sample is in a melt state, the gas will enter the fluid melt under a certain pressure. After cooling and crystallization, the air will be fixed inside the spline due to the disappearance of the melt fluidity, resulting in spline preparation errors.

[0032] In addition, during the melt crystallization process, due to the pressure exerted by the rotating screw, no bubbles or "Coanda effect" will be generated during the melt's sudden cooling and volume contraction; in addition, the sample cavity is a hollow cylindrical structure, and under the action of the rotating screw, a uniform columnar spline that meets the test requirements can be produced, thereby ensuring the spline preparation effect and improving the accuracy of the test results.

[0033] The present application also provides a preparation method implemented using the above-mentioned preparation device. The preparation method first calculates the mass of the corresponding volume of sample through density calculation, adds the sample to the sample cavity, heats it to a molten state, and applies continuous pressure by rotating the screw to reduce the flow space of the melt, while simultaneously expelling the air in the cavity through the bolt seal. When the molten sample overflows from the bolt seal, the screw is stopped from rotating and the heating is stopped. The sample cavity is placed in a low-temperature cooling chamber for a quenching process. The polymer quickly crystallizes to form a glue seal. At the same time, the screw is rotated rapidly to provide pressure to expel the polymer crystals, avoiding the influence of air during the melt volume shrinkage process, thereby preparing a uniform spline that meets the test requirements of the time-domain nuclear magnetic resonance analyzer, greatly improving the accuracy of the analyzer test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0035] Figure 1 This is a schematic diagram of the structure of a nuclear magnetic resonance tube in the prior art;

[0036] Figure 2 This is a schematic diagram of the structure of a time domain nuclear magnetic resonance analyzer sample testing device provided in an embodiment of the present application;

[0037] Figure 3 This is a schematic diagram of the front structure of a time domain nuclear magnetic resonance analyzer test sample device provided in an embodiment of the present application;

[0038] Figure 4 A top view of a time-domain nuclear magnetic resonance analyzer test sample device provided in an embodiment of the present application;

[0039] Figure 5 This is a schematic diagram of the sample chamber, screw and bolt sealing structure of the time domain nuclear magnetic resonance analyzer sample testing device provided in an embodiment of the present application.

[0040] In the figure: 1, nuclear magnetic resonance tube 2, heating chamber 3, sample chamber 4, bolt seal 5, screw 6, cooling chamber 7, fixed bottom plate 8, fixed column 9, fixed top plate 10, through hole 11, limit seal 12, sample. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0042] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0043] like Figures 2 to 5 As shown, in this embodiment, a device for preparing test samples for a time-domain nuclear magnetic resonance analyzer is provided. The device includes a hollow cylindrical sample chamber 3 for filling a sample 12. The sample chamber 3 has an overall cylindrical structure and a hollow cylindrical structure inside. The splines prepared by the preparation device meet the requirements of 8.0±0.2mm and 12.0±0.2mm uniform columnar splines. Of course, for time-domain nuclear magnetic resonance analyzers of different models or manufacturers, the structure of the sample chamber 3 can be adaptively adjusted according to their spline requirements, and all of these fall within the scope of protection of this application.

[0044] It should be noted that this application takes the Minispec time-domain nuclear magnetic resonance analyzer as an example. On this basis, the required spline specifications are uniform columnar splines with a diameter of about 8 mm and a height of about 12 mm. Then the diameter of the sample cavity 3 is set to 8.0±0.2 mm. When the diameter is constant, the specific weight of the sample 12 is required through density calculation. When the spline is formed, its height can naturally reach 12.0±0.2 mm.

[0045] A bolt seal 4 is provided at one end of the sample chamber 3 and is connected to the sample chamber 3 by means of a bolt connection. Meanwhile, a screw 5 is provided at the other end of the sample chamber 3 and extends into the sample chamber 3. To ensure a tight seal between the screw 5 and the sample chamber 3 and prevent air from re-entering the sample 12, the outer wall of the screw 5 is sealedly connected to the inner wall of the sample chamber 3 via a threaded connection, thereby preventing air from entering the sample chamber 3 from the point where the outer wall of the screw 5 contacts the inner wall of the sample chamber 3.

[0046] Of course, after the sample 12 is filled into the sample cavity 3, it can be filled in from the end of the screw 5 or the end of the bolt seal 4, and then the screw 5 or the bolt seal 4 is installed in the sample cavity 3. The filled sample 12 needs to be heated and melted to reach a molten state. In this embodiment, the heating cavity 2 is sleeved on the outer periphery of the sample cavity 3 and can be slid relative to the sample cavity 3, so that the sample 12 in the sample cavity 3 is fully and evenly heated and melted.

[0047] The melted sample 12 requires a quenching process to achieve rapid crystallization. In this embodiment, this is achieved by a cooling chamber 6 containing a 0-4°C ice-water mixture, allowing the melt to crystallize and form a seal. During the melting process, the rotating screw 5 provides continuous pressure to reduce the space available for the melt to flow. At the same time, the bolt seal 4 removes air from the chamber, preventing the air inside the sample chamber 3 from affecting the melt.

[0048] In addition, based on the above-mentioned specification splines, when the sample 12 is in the sample cavity 3, the inner wall of the corresponding sample cavity 3 is a smooth cylindrical surface, which can make the outer wall of the spline uniform and meet the preparation standard, and facilitate the rapid discharge of the spline.

[0049] In summary of the above embodiments, the sample chamber 3 of the present application is provided with a bolt seal 4 and a screw 5 at both ends respectively. The bolt seal 4 is threadedly connected to the sample chamber 3 and has a certain sealing effect, but it cannot be completely sealed. Therefore, under the pressure of the rotating screw 5, the gas in the sample chamber 3 will be discharged from the bolt seal 4 to the outside of the sample chamber 3. Specifically, when the sample 12 is in a melt state, the gas will enter the melt with fluidity under a certain pressure. After cooling and crystallization, the air will be fixed inside the spline due to the disappearance of the melt fluidity, resulting in preparation errors in the spline. In addition, during the crystallization process of the melt, due to the pressure applied by the rotating screw 5, no bubbles or "Coanda effect" will be generated during the process of sudden cooling and volume contraction of the melt; in addition, the sample chamber 3 is a hollow cylindrical structure, and under the action of the rotating screw 5, a uniform columnar spline that meets the test requirements can be produced, thereby ensuring the preparation effect of the spline and improving the accuracy of the test results.

[0050] It should be noted that, since the spline needs to be discharged from the seal after cooling and crystallization, in order to prevent the bolt seal 4 and the corresponding internal thread on the inner wall of the sample chamber 3 from affecting the overall specifications of the spline, the minor diameter of the internal thread here is set to be larger than the inner diameter of the sample chamber 3; of course, the minor diameter of the internal thread here refers to the diameter of the bottom of the internal thread, that is, the diameter of the bottom of the internal thread is larger than the inner diameter of the sample chamber 3, and the spline will not contact the internal thread here during the discharge process and will not be affected by the internal thread here. For the threaded connection method, there is no need to make too many requirements on its accuracy, that is, a partial sealing effect can be achieved through threaded connection, and there is no need to achieve complete sealing, so as to ensure that the air inside the sample chamber 3 can be discharged. Of course, for the threaded connection method between the screw 5 and the sample chamber 3, higher processing accuracy requirements can be adopted to achieve direct thread sealing; at the same time, sealing methods such as raw tape can also be used, but it is necessary to ensure that it does not affect the purpose of achieving its axial transmission through rotation.

[0051] In addition, since the heating chamber 2 needs to heat the sample 12 inside the sample chamber 3, the sample chamber 3 and the heating chamber 2 here are made of heat-conducting metal materials with fixed shapes, such as 45 steel or other high-temperature resistant alloys, which are replaced or replaced. They will not be described in detail here. It should be pointed out that a heater is provided inside the heating chamber 2. The heater can be a resistance wire or other electric heating component. The heating chamber 2 is externally connected to a temperature control box to achieve independent temperature regulation of the heating chamber 2, so that a larger temperature range can be achieved. Of course, the setting of the heater does not affect the insertion of the sample chamber 3, and in order to make the sample 12 fully melted, the heater here must first heat the cavity of the heating chamber 2. The heated cavity can then evenly heat the periphery of the sample chamber 3, so that the sample 12 is evenly heated and melted more fully.

[0052] The heating chamber 2 is also provided with a thermocouple for detecting its temperature. The thermocouple is externally connected to a temperature control box, which can provide timely feedback on the heating temperature of the heating chamber 2, making it easier for operators to observe and perform the next operation.

[0053] On the basis of the above embodiments, the preparation device of the present application also includes a fixed bottom plate 7 and a fixed top plate 9. The heating chamber 2 and the cooling chamber 6 are fixedly arranged on the fixed bottom plate 7, and the openings of both are set upward. A fixed top plate 9 is arranged above the heating chamber 2 and the cooling chamber 6. The fixed bottom plate 7 is fixedly connected to the fixed bottom plate 7 through a fixed column 8, thereby forming a stable rectangular frame structure. Of course, the heating chamber 2 and the cooling chamber 6 need to be spaced apart from the fixed top plate 9.

[0054] It is worth noting that through holes 10 corresponding to the positions of the heating chamber 2 and the cooling chamber 6 are respectively provided on the fixed top plate 9, and the sample chamber 3 is placed in the heating chamber 2 or the cooling chamber 6 through the through hole 10; that is, when the sample 12 is heated and melted, the sample chamber 3 can be extended into the heating chamber 2 through the through hole 10 above the heating chamber 2; after the heating and melting is completed, the sample chamber 3 is taken out as a whole, and then extended into the cooling chamber 6 through the through hole 10 above the cooling chamber 6 to complete the cooling crystallization.

[0055] Furthermore, the end of the sample chamber 3 away from the bolt seal 4 is provided with a limit seal 11 that engages with the bolt seal 4. Figure 2 As shown, the inner wall of the limiting seal 11 is threadedly connected to the outer wall of the sample chamber 3, the screw 5 passes through the limiting seal 11 and extends into the sample chamber 3, and the screw 5 moves axially relative to the limiting seal 11; specifically, the setting of the limiting seal 11 does not affect the rotation of the screw 5. Of course, the screw 5 can move axially while rotating.

[0056] Furthermore, since the sample cavity 3 needs to pass through the through hole, the outer diameter of the through hole 10 needs to be larger than the outer diameter of the sample cavity 3. At the same time, the outer wall of the limiting seal 11 is in abutment against the inner wall of the through hole 10. Therefore, the outer diameter of the limiting seal 11 naturally needs to be larger than the outer diameter of the sample cavity 3, thereby ensuring that the sample cavity 3 and the screw 5 will not swing at will in the through hole 10, providing a certain support force for the rotating screw 5.

[0057] It should be noted that the fixed bottom plate, the fixed top plate and the cooling cavity can be made of POM (polyoxymethylene) material, and can be replaced or replaced by PP (polypropylene) or PMP (poly-4-methyl-1-pentene).

[0058] In addition, the present application also provides a preparation method implemented using the above-mentioned preparation device, which comprises the following steps:

[0059] Step a: Calculate the mass of the corresponding volume of sample 12 by density calculation and add it to the sample cavity 3. It should be noted that since some molten sample overflowed in step e, the amount of sample 12 added can be appropriately increased to ensure that the final spline can meet the requirements.

[0060] Step b: Insert the end of the sample chamber 3 with the bolt seal 4 into the heating chamber 2, and ensure that the corresponding range of the sample 12 is within the heating chamber 2; this is to ensure that the sample 12 can be fully melted and that the sample 12 in the heating chamber 2 can be directly heated;

[0061] Step c: The heating chamber 2 is heated to above 30° C., and the sample 12 is heated and melted evenly. Generally speaking, this step can be maintained for a certain time to ensure that the sample 12 is fully melted.

[0062] Step d: Rotate the screw 5 to provide pressure to the molten sample, reduce the space where the melt can flow, and expel the air in the cavity through the bolt seal 4;

[0063] In addition, the air between the sample 12 and the screw 5 can be discharged to the space between the sample 12 and the bolt seal 4 by rotating the screw 5 before the sample 12 is completely melted;

[0064] Step e: After the molten sample overflows from the bolt seal 4, the screw 5 is stopped from rotating and the heating is stopped. It should be noted that the melted sample 12 also has a liquid sealing function. When the molten sample overflows, it indicates that there is no air in the sample chamber 3. Then, there is no need to apply pressure through the screw 5, and the screw 5 can be stopped. At this time, both ends of the molten sample are in a sealed state.

[0065] Step f: Place the sample cavity 3 into the cooling cavity 6, and allow the molten sample to crystallize quickly to form a glue seal. Simultaneously, the screw 5 is rotated quickly to provide pressure to expel the crystals and avoid the influence of air during the volume shrinkage of the melt.

[0066] Through the above steps, a uniform spline with a size that meets the test requirements of the time domain nuclear magnetic resonance analyzer is prepared, which greatly improves the accuracy of the analyzer test results.

[0067] It should be noted that, in this specification, relational terms such as first and second are merely used to distinguish one entity from other entities, but do not necessarily require or imply any actual relationship or order between these entities.

[0068] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core ideas of this application. It should be noted that for those skilled in the art, without departing from the principles of this application, various improvements and modifications can be made to this application, and such improvements and modifications also fall within the scope of protection of the claims of this application.

Claims

1. A method for preparing a test sample for a time domain nuclear magnetic resonance analyzer, characterized in that: The method is implemented by using a sample preparation device for a time domain nuclear magnetic resonance analyzer, wherein the preparation device includes a hollow cylindrical sample chamber for filling the sample, and further includes: A bolt seal is located at one end of the sample cavity and is threadedly connected to the sample cavity; A screw rod extends into the other end of the sample chamber, and the outer wall of the screw rod is threadedly and sealedly connected to the inner wall of the sample chamber; A heating chamber is sleeved on the periphery of the sample chamber and is slidably arranged with the sample chamber, and is used to heat and melt the sample in the sample chamber; A cooling chamber is provided with a 0-4°C ice-water mixture. After the sample is heated and melted, the sample chamber is placed in the cooling chamber to crystallize the sample. The sample is located between the end of the screw and the bolt seal, and the inner wall of the sample cavity corresponding to the sample is a smooth cylindrical surface; The preparation method comprises: Step a, obtaining the mass of the sample of corresponding volume by density calculation, and adding the sample into the sample chamber; Step b, extending the sample cavity into the heating cavity, and ensuring that the corresponding range of the sample is within the heating cavity; Step c, heating the heating chamber to above 30° C., and uniformly melting the sample; Step d, rotating the screw to provide pressure for the molten sample, reducing the flow space of the melt, and at the same time exhausting the air in the cavity through the bolt seal; Step e: until the molten sample overflows from the bolt seal, stop rotating the screw and stop heating; Step f: placing the sample cavity into the cooling cavity, allowing the molten sample to crystallize quickly to form a glue seal, while simultaneously rapidly rotating the screw to provide pressure to expel the crystals.

2. The method for preparing a time domain nuclear magnetic resonance analyzer test sample according to claim 1, wherein: An internal thread is provided on the inner wall of the sample cavity corresponding to the bolt seal, and the minor diameter of the internal thread is larger than the inner diameter of the sample cavity.

3. The method for preparing a time domain nuclear magnetic resonance analyzer test sample according to claim 2, wherein: The sample cavity and the heating cavity are made of heat-conducting and high-temperature-resistant 45# steel. The heating cavity has a built-in electric heater, and the electric heater is externally connected to a temperature control box.

4. The method for preparing a time domain nuclear magnetic resonance analyzer test sample according to claim 3, wherein: The heating chamber is also provided with a thermocouple for detecting the temperature thereof, and the thermocouple is externally connected to the temperature control box.

5. The method for preparing a time domain nuclear magnetic resonance analyzer test sample according to any one of claims 1 to 4, characterized in that: Also includes: A fixed bottom plate, on the end surface of which the heating chamber and the cooling chamber are fixedly arranged; a fixed top plate, fixedly connected to the fixed bottom plate via a fixing column, wherein the heating chamber and the cooling chamber are both located between the fixed bottom plate and the fixed top plate, and are spaced apart from the fixed top plate; Wherein, through holes corresponding to the positions of the heating cavity and the cooling cavity are respectively provided on the fixed top plate, and the sample cavity passes through the through holes and is placed in the heating cavity or the cooling cavity.

6. The method for preparing a time domain nuclear magnetic resonance analyzer test sample according to claim 5, characterized in that: The end of the sample cavity away from the bolt seal is provided with a limit seal that is engaged with the bolt seal. The inner wall of the limit seal is threadedly connected to the outer wall of the sample cavity. The screw penetrates the limit seal and extends into the sample cavity, and the screw moves axially relative to the limit seal.

7. The method for preparing a time domain nuclear magnetic resonance analyzer test sample according to claim 6, wherein: The outer diameter of the position-limiting seal is larger than the outer diameter of the sample cavity and is located in the through hole. The outer wall of the position-limiting seal abuts against the inner wall of the through hole to limit the shaking of the sample cavity and the screw in the through hole.

8. The method for preparing a time domain nuclear magnetic resonance analyzer test sample according to claim 5, characterized in that: The fixed bottom plate, the fixed top plate and the cooling chamber are made of POM material.

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