Hollow fiber membrane water contact angle test tool

Abstract

This invention discloses a testing fixture for the water contact angle of hollow fiber membranes, including a support assembly, a carrier assembly, an adhesive assembly, a display assembly, and a lifting assembly. The support assembly is symmetrically arranged on both sides, and each of the two sets of support assemblies has a carrier assembly for placing the component on its surface. The carrier assembly has an adhesive assembly for positioning the material on its surface. This invention solves the problem of the lack of an effective method to evaluate the hydrophilicity and hydrophobicity of the inner surface of hollow fiber dialysis membranes by coordinating the components, carrier assembly, adhesive assembly, display assembly, lifting assembly, and stopwatch. The testing method is simple and effective, requiring no special tools or equipment. This testing method and fixture can meet the requirements for rapid evaluation of the contact angle of the inner surface of hollow fiber membranes at the micron level. The testing method is simple, the testing cost is low, and the test results have high reliability. Therefore, it can be used as an evaluation tool for the hydrophilicity and hydrophobicity of the inner surface of hollow fiber membranes.

Description

Technical Field

[0001] This utility model relates to the field of hollow fiber membrane testing technology, specifically to a hollow fiber membrane water contact angle testing fixture. Background Technology

[0002] Contact angle testing is the most direct and rapid method for evaluating changes in the hydrophilicity and hydrophobicity of a material surface. For testing the contact angle of the outer surface of hollow fiber membranes, the standard HY / T266-2018, "Contact Angle Method for Testing the Hydrophilicity of Externally Pressurized Hollow Fiber Ultrafiltration Membranes," can be used. This method directly measures the angle between the solid, liquid, and gas interfaces during the contact between a droplet and the outer surface of the hollow fiber membrane to evaluate the change in the membrane's hydrophilicity. However, this method is only suitable for hollow fiber membranes with consistent hydrophilicity on both the inner and outer surfaces, using the outer contact angle as an evaluation index of the overall hydrophilicity of the hollow fiber membrane material. For membranes with inconsistent hydrophilicity on the inner and outer surfaces, it is necessary to measure the contact angles of the inner and outer surfaces separately. Before measuring the inner surface contact angle, the hollow fiber membrane needs to be dissected to expose the inner surface for testing. For smaller hollow fiber membranes, the transverse dissection of the membrane fibers and the testing process are very difficult.

[0003] Currently, there is no relevant testing method for measuring the contact angle of the inner surface of small-sized hollow fiber membranes. For example, hollow fiber dialysis membranes have an inner diameter of 200 micrometers and a wall thickness of 40 micrometers. After the inner surface has undergone hydrophilic modification treatment, it is necessary to evaluate the size of the inner surface contact angle. However, there is currently no effective method or instrument for measuring the size of the contact angle of the inner surface of small-sized hollow fiber membranes. Therefore, we propose a testing fixture for evaluating the water contact angle of the inner surface of small-sized hollow fiber membranes. Utility Model Content

[0004] The purpose of this invention is to provide a hollow fiber membrane water contact angle testing fixture. This fixture can meet the requirements for rapid evaluation of the contact angle of the inner surface of hollow fiber membranes at the micron level. The testing method is simple, the testing cost is low, and the test results are reliable, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a hollow fiber membrane water contact angle testing fixture, comprising a support assembly, a load-bearing assembly, an adhesive assembly, a display assembly, and a lifting assembly;

[0006] The support components are symmetrically arranged on both sides. The surfaces of both sets of support components are provided with bearing components for placing parts. The surfaces of the bearing components are provided with adhesive components for material positioning. The surfaces of the bearing components are provided with display components for height observation. The inner sides of the two sets of support components are provided with lifting components for adjusting liquid height.

[0007] A stopwatch for recording the rise time of the membrane filament is bolted to the top of the support assembly.

[0008] Preferably, the support assembly includes a first iron frame platform and a second iron frame platform, which are equidistant and symmetrically arranged, and are located outside the lifting assembly.

[0009] Preferably, the load-bearing component includes a first fixed crossbeam and a second fixed crossbeam, both of which are bolted to the surfaces of the first iron frame and the second iron frame, and the first fixed crossbeam and the second fixed crossbeam are arranged at equal intervals.

[0010] Preferably, the adhesive component includes double-sided adhesive, which is adhered to the surfaces of the first fixed crossbeam and the second fixed crossbeam, and a hollow fiber membrane is adhered to the surface of the double-sided adhesive.

[0011] Preferably, the display component includes a first scale and a second scale, both of which are adhered to the surface of double-sided adhesive.

[0012] Preferably, the lifting assembly includes a manual lifting platform, a test solution, and a glass container. The manual lifting platform is located between a first iron frame and a second iron frame. The glass container is placed on top of the manual lifting platform, and the test solution is placed inside the glass container.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] This invention solves the problem of lacking an effective method to assess the hydrophilicity and hydrophobicity of the inner surface of hollow fiber dialysis membranes by coordinating components, a support component, an adhesive component, a display component, a lifting component, and a stopwatch. The test method is simple and effective, requiring no special tools or equipment. This test method and fixture can meet the requirements for rapid assessment of the contact angle of the inner surface of hollow fiber membranes at the micron level. The test method is simple, the test cost is low, and the test results have high reliability. Therefore, it can be used as an assessment method for the hydrophilicity and hydrophobicity of the inner surface of hollow fiber membranes.

[0015] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objectives and other advantages of this invention can be realized and obtained through the structures pointed out in the description and the accompanying drawings. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model;

[0017] Figure 2 This is a schematic diagram of the stopwatch structure of this utility model;

[0018] Figure 3 This is a schematic diagram of the manual lifting platform structure of this utility model;

[0019] Figure 4 This is a schematic diagram showing the rise of the liquid on the inner surface of the membrane according to this invention;

[0020] Figure 5 This is a schematic diagram of the contact angle of the flat sheet film in Formula 1 of this utility model;

[0021] Figure 6 This is a schematic diagram of the contact angle of the flat sheet film in Formula 2 of this utility model.

[0022] In the diagram: 1. First fixed crossbeam; 2. Second fixed crossbeam; 3. First iron frame; 4. First ruler; 5. Hollow fiber membrane; 6. Second ruler; 7. Double-sided tape; 8. Second iron frame; 9. Stopwatch; 10. Manual lifting platform; 11. Test solution; 12. Glassware. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0024] This utility model provides a hollow fiber membrane water contact angle testing fixture, including a support component, a load-bearing component, an adhesive component, a display component, and a lifting component;

[0025] The support components are arranged symmetrically on both sides. The surfaces of both sets of support components are provided with carrier components for placing the components. The surfaces of the carrier components are provided with adhesive components for material positioning. The surfaces of the carrier components are provided with display components for height observation. The inner sides of the two sets of support components are provided with lifting components for adjusting the liquid height. A stopwatch 9 for recording the rise time of the membrane filament is attached to the top of the support components.

[0026] Preferred;

[0027] like Figure 2 As shown, the support assembly includes a first iron frame platform 3 and a second iron frame platform 8. The first iron frame platform 3 and the second iron frame platform 8 are symmetrically arranged at equal intervals. The first iron frame platform 3 and the second iron frame platform 8 are located outside the lifting assembly and serve to support the components and membrane fibers on the following and this surface.

[0028] further;

[0029] like Figure 2As shown, the load-bearing component includes a first fixed crossbeam 1 and a second fixed crossbeam 2. Both the first fixed crossbeam 1 and the second fixed crossbeam 2 are bolted to the surfaces of the first iron frame platform 3 and the second iron frame platform 8. The first fixed crossbeam 1 and the second fixed crossbeam 2 are arranged at equal intervals, which is beneficial for supporting the structural components bonded to the surface.

[0030] Going a step further;

[0031] like Figure 2 As shown, the bonding assembly includes double-sided adhesive 7, which is bonded to the surfaces of the first fixed crossbeam 1 and the second fixed crossbeam 2. A hollow fiber membrane 5 is bonded to the surface of the double-sided adhesive 7, which can bond the following display components and membrane fibers.

[0032] in,

[0033] like Figure 2 As shown, the display component includes a first scale 4 and a second scale 6, both of which are adhered to the surface of the double-sided adhesive 7, for measuring the rise height of the membrane filament and for measuring the rise height of the solution during the membrane filament test.

[0034] at last;

[0035] like Figure 3 As shown, the lifting assembly includes a manual lifting platform 10, a test solution 11, and a glass container 12. The manual lifting platform 10 is located between the first iron frame 3 and the second iron frame 8. The glass container 12 is placed on top of the manual lifting platform 10, and the test solution 11 is placed inside the glass container 12. The manual lifting platform 10 is a conventional hand-cranked lifting platform with a self-locking mechanism.

[0036] The test fixture is assembled as shown in the figure. The first fixed crossbeam 1 and the second fixed crossbeam 2 are bolted to the surfaces of the first iron frame 3 and the second iron frame 8. Two sets of double-sided tape 7 are then attached to the surfaces of the first fixed crossbeam 1 and the second fixed crossbeam 2, respectively. The first scale 4 and the second scale 6 are then attached and fixed as shown in the figure. The stopwatch 9 is installed on the second iron frame 8 on the right side. The hollow fiber membrane 5 is then removed and attached to the surface of the double-sided tape 7, and placed as shown in the figure. The glass container 12 is removed, and after adding the test solution 11 inside, it is placed on top of the manual lifting platform 10. The manual lifting platform 10, along with the glass container 12, is positioned below the hollow fiber membrane 5. The manual lifting platform 10 is then rotated to lift and move the glass container 12 upwards until it reaches the desired position. Figure 1 The position and height displayed in the image.

[0037] When using the aforementioned hollow fiber membrane water contact angle testing fixture to test the hollow fiber membrane, the testing method is as follows:

[0038] 1) Test fixture setup: according to Figure 1 Set up the testing fixtures and prepare other tools needed for the test;

[0039] 2) Test sample preparation: Prepare hollow fiber membrane samples required for testing. Prepare at least 20 hollow fiber membrane samples for each type of test sample. When selecting membrane samples, ensure that the membrane sample size is not deformed by compression, and the length of the test sample should be greater than 15cm.

[0040] 3) Preparation of dyeing solution: In order to facilitate the observation of the rising height of the hollow fiber membrane in the liquid during the test, dye needs to be added to the test liquid to prepare a dyeing solution. The types of dyes used in the dyeing solution include, but are not limited to, methylene blue, Congo red, fuchsin, Sudan red, rhodamine, and fluorescent dyes. The dyes are prepared with pure water, and the concentration of the prepared dyeing solution aqueous solution is between 0.05 and 2 mg / L, preferably between 0.15 and 0.3 mg / L.

[0041] 4) Inner diameter of the fiber membrane sample during testing: Before testing, the size of the hollow fiber membrane needs to be measured for the calculation of the contact angle. A microscopic image measuring instrument is used to measure the inner surface diameter of the hollow fiber membrane sample to be tested. Each sample is measured 5 times, and the average value is taken as the inner surface diameter of the hollow fiber membrane sample.

[0042] 5) Hollow fiber membrane sample fixing: After the measurement is completed, the hollow fiber membrane samples to be tested are sequentially glued to the fixed crossbeam. In order to ensure the accuracy of the test results, there should be ≥3 parallel samples, preferably 5 parallel samples. During the process of gluing and fixing the parallel samples of hollow fiber membrane, the samples should not be deformed. The hollow fiber membrane samples should be kept in a natural vertical state, and the parallel samples should be evenly distributed. In order to facilitate operation, the interval between parallel samples should be greater than 1cm. After fixing the parallel samples, use a sharp blade to cut the lower end of the hollow fiber membrane so that the lower end face of the parallel samples is at the same level. During the cutting process, care should be taken to keep the cut end face flat and free from deformation.

[0043] 6) Immersion test: Add the prepared dyeing solution to the container and place it on the manual lifting platform so that the dyeing solution is directly below the hollow fiber membrane sample. Slowly raise the lifting platform so that the lower end of the hollow fiber membrane sample contacts the dyeing solution and the lower end of the hollow fiber membrane is submerged in the dyeing solution to a depth ≥1mm. During the test, the temperature of the dyeing solution is measured and recorded.

[0044] 7) Staining height recording: Due to the capillary effect, the staining solution will gradually rise along the inner surface of the membrane filament and reach the maximum rising height. Observe and record the rising of the staining solution in the membrane filament, and measure and record the maximum rising height and rising time.

[0045] 8) Contact Angle Calculation: According to the Young-LaPlace equation for the capillary effect, the capillary effect is an interaction between a solid surface and a liquid surface. Since the hollow fiber membrane is small in size and has a regular hollow structure, the capillary effect can be used to measure the water absorption height of the inner surface of the hollow fiber membrane in water. Then, the contact angle of the inner surface of the hollow fiber membrane can be indirectly calculated using the Young-LaPlace equation ρgh=2γcosθ / r. As shown in Equation 1 below, the contact angle of the inner surface of the hollow fiber membrane can be calculated using the above test data:

[0046] ρg(h-h0)=(2γcosθ) / r;

[0047] Where: ρ is the density of water under the corresponding temperature conditions, in kg / m3;

[0048] g is the acceleration due to gravity, which is 9.8 m / s².

[0049] h represents the capillary rise height, in meters (m).

[0050] h0 is the depth of the membrane fiber immersed in the liquid surface, in meters (m).

[0051] γ is the surface tension of water under the corresponding temperature conditions, with units of N / m;

[0052] r is the inner radius of the capillary tube, in meters (m).

[0053] θ is the contact angle of the inner surface of the capillary.

[0054] Comparative Example 1;

[0055] First, the test setup was prepared in the laboratory. Then, a 0.25 mg / L methylene blue aqueous solution was prepared as the staining solution. Hollow fiber dialysis membrane samples (inner diameter 200 ± 20 μm, wall thickness 40 ± 5 μm) were prepared for the test. Preliminary tests were conducted to observe and determine the rising pattern and stability of the membrane fibers in the staining solution. The rising of the liquid on the inner surface of two different types of hollow fiber membranes (samples 1# and 2#) after contact with the staining solution was measured and recorded. The rising height at different times was measured and recorded. The test results are as follows: Figure 4 As shown in the figure, the liquid initially rises rapidly within the hollow fiber membrane, then the rising speed gradually slows down, reaching its maximum height before ceasing to rise. The rising process curve exhibits a clear regularity. Both hollow fiber dialysis membrane samples tested reached their maximum rising height within 20 minutes. Figure 4 As shown.

[0056] Comparative Example 2

[0057] Furthermore, four different batches of samples of the same type were selected, and the contact angle of the membrane fiber samples was further measured and calculated to determine the stability of the test results of this method. The entire test was conducted at room temperature, and the temperature of the test liquid was 15℃. By referring to the standard, the density of water at this temperature was found to be 0.999099 kg / m³, and the surface tension of water was 0.07439 N / m. Before the formal test, the inner diameter of the membrane fiber samples was measured. During the test, the rise height of the methylene blue aqueous solution in the membrane fiber was recorded. The specific test calculation results are shown in Table 1 below:

[0058] Table 1. Calculation results of contact angle tests for different batches of membranes.

[0059]

[0060]

[0061] As shown in Table 1, the maximum rising height was reached when the dye solution rose for 20 minutes. The test calculation showed that the contact angle of the inner surface of the four batches of hollow fiber membrane samples of Sanxin 160H was about 45°. The test results of different batches of membrane fibers showed relatively high stability.

[0062] Comparative Example 3

[0063] To determine the accuracy of this method for measuring material surface contact angles, a water contact angle meter was used to measure and compare the contact angles of flat sheet membranes (which differ only in shape, with similar internal structures and surface morphology) prepared under the same formulation conditions as hollow fiber membranes. Two different hydrophilic / hydrophobic membrane formulations (Formulation 1: existing production line formulation; Formulation 2: hydrophobic modified formulation) were selected to prepare hollow fiber membranes and flat sheet membranes, and their contact angles were compared. The results are shown in the table below. The comparison results show that the contact angles of hollow fiber membranes and flat sheet membranes prepared with the same formulation and process are very close, indicating that the contact angles obtained by this method for hollow fiber membranes have high accuracy.

[0064] Table 2 Comparison of contact angle test results for hollow fiber membranes and flat sheet membranes

[0065]

[0066] like Figure 5 The results of the contact angle test for the sheet film of Formulation 1 are shown below. Figure 6 The results of the contact angle test for the flat sheet film of Formulation 2 are shown.

[0067] Based on the above, the test method and test device can meet the requirements for rapid evaluation of the contact angle of the inner surface of hollow fiber membranes at the micron level. The test method is simple, the test cost is low, and the test results have high reliability. Therefore, it can be used as an evaluation of the hydrophilicity and hydrophobicity of the inner surface of hollow fiber membranes.

[0068] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fixture for testing the water contact angle of a hollow fiber membrane, characterized in that, This includes support components, load-bearing components, adhesive components, display components, and lifting components; The support components are symmetrically arranged on both sides. The surfaces of both sets of support components are provided with bearing components for placing parts. The surfaces of the bearing components are provided with adhesive components for material positioning. The surfaces of the bearing components are provided with display components for height observation. The inner sides of the two sets of support components are provided with lifting components for adjusting liquid height. A stopwatch (9) for recording the rise time of the membrane filament is bolted to the top of the support assembly.

2. The hollow fiber membrane water contact angle testing fixture according to claim 1, characterized in that: The support assembly includes a first iron frame platform (3) and a second iron frame platform (8), which are equidistantly and symmetrically arranged, and are located outside the lifting assembly.

3. The hollow fiber membrane water contact angle testing fixture according to claim 2, characterized in that: The load-bearing component includes a first fixed crossbeam (1) and a second fixed crossbeam (2). The first fixed crossbeam (1) and the second fixed crossbeam (2) are both bolted to the surfaces of the first iron frame (3) and the second iron frame (8). The first fixed crossbeam (1) and the second fixed crossbeam (2) are arranged at equal intervals.

4. The hollow fiber membrane water contact angle testing fixture according to claim 3, characterized in that: The adhesive assembly includes double-sided adhesive (7), which is bonded to the surfaces of the first fixed crossbeam (1) and the second fixed crossbeam (2), and a hollow fiber membrane (5) is bonded to the surface of the double-sided adhesive (7).

5. The hollow fiber membrane water contact angle testing fixture according to claim 4, characterized in that: The display component includes a first ruler (4) and a second ruler (6), both of which are adhered to the surface of double-sided tape (7).

6. The hollow fiber membrane water contact angle testing fixture according to claim 2, characterized in that: The lifting assembly includes a manual lifting platform (10), a test solution (11), and a glass container (12). The manual lifting platform (10) is located between the first iron frame (3) and the second iron frame (8). The glass container (12) is placed on top of the manual lifting platform (10), and the test solution (11) is placed inside the glass container (12).

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