A method for quantitatively detecting the stability of superhydrophobic performance of superhydrophobic paper-based materials

Abstract

This invention provides a method for quantitatively detecting the stability of superhydrophobic properties of superhydrophobic paper-based materials. The specific steps are as follows: The sample to be tested is sealed to a glass slide with waterproof sealing tape; the number of test samples to be prepared is calculated based on the test conditions; the prepared sample is placed in a constant temperature and humidity chamber with pre-set test conditions, and the sample is taken out sequentially according to the designed test intervals; the contact angle and roll-off angle of the contact and non-contact surfaces of the taken-out sample are measured using a contact angle measuring instrument; based on the contact angle and roll-off angle of both sides of the superhydrophobic paper-based sample measured throughout the entire test cycle, the stabilization time T of the sample's superhydrophobic properties is calculated. s and the final stable value θ of the contact angle c (°), the rolling hysteresis time T of the superhydrophobic properties of the sample. L And determine the final stable value θ of the roll angle. s (°). This detection method is suitable for superhydrophobic paper-based samples of various sizes and shapes, and features convenient detection, high measurement accuracy, and good reproducibility.

Description

Technical Field

[0001] The invention belongs to the technical field of super-hydrophobic paper-based materials, and particularly relates to a method for quantitatively detecting the stability of super-hydrophobic performance of super-hydrophobic paper-based materials. Background Art

[0002] In recent years, as people have become more and more aware of the serious environmental pollution caused by non-degradable materials such as plastic products, paper-based materials, as the most representative sustainable natural green materials, have played an increasingly important role in daily life and production. However, since paper-based materials without any modification have strong hygroscopicity, the strength index of paper-based materials after absorbing moisture is significantly reduced, which affects the subsequent use performance of paper-based materials. In the traditional pulping and papermaking industry, paper-based materials are given the ability to resist the penetration and diffusion of liquids (especially water or water-based solutions) through the treatment of sizing in the pulp or on the surface. As the application field of paper-based materials gradually expands, traditional sizing technology has long been unable to meet the requirements of some industries for the performance of paper-based materials. In order to make full use of the recyclable, renewable, biodegradable green and environmentally friendly natural polymer material-wood fiber paper-based materials, scientific and technical personnel have conducted a relatively systematic study of hydrophobic modification processes and related theories through biological, chemical and physical modification methods to target the common problem of this raw material in many application fields: poor waterproof performance (native hydrophilicity), especially the hydrophobic modification of paper-based materials (the main application form of wood fiber cellulose).

[0003] The report of super-hydrophobic phenomenon has given researchers new research ideas for the preparation of waterproof and moisture-proof paper-based materials. The wettability of solid surfaces is usually characterized by contact angles. Super-hydrophobic surfaces refer to surfaces with static apparent contact angles of ≥150° and rolling angles of <10° formed between liquid water droplets and solid surfaces. If natural biodegradable green wood fiber-based materials are given anti-adhesion, self-cleaning, super-waterproof and other application properties through super-hydrophobic modification, such new materials will have great application potential in many fields. Therefore, super-hydrophobic papers based on different preparation principles and processes have been reported one after another, such as physical and chemical modification (template method, plasma method, impregnation method and papermaking filler method, etc.), surface coating, chemical modification (phase separation method, layer-by-layer assembly method), nanoparticle deposition method, etc. According to the latest search, there are more than 11,900 Chinese and foreign scientific and technological literature related to super-hydrophobic paper, and there are more than 30 Chinese authorized patents related to the preparation of super-hydrophobic paper alone.

[0004] In the field of super-hydrophobic paper-based materials, most of the current research is mainly focused on the development of new materials and new technologies, and there are few reports on the influence of the three-dimensional network structure of paper-based fibers on the stability of the super-hydrophobicity of the surface. Since super-hydrophobicity is closely related to the rough structure of the material surface, under the influence of external conditions (such as high humidity environment), the change of the fiber network structure inside the paper base may cause the change of the rough structure of the paper base surface, thereby further affecting the surface super-hydrophobicity of the paper-based material. In addition, super-hydrophobic paper-based materials have two-sidedness under different temperature and humidity conditions, and the stability of the super-hydrophobicity of one side (contact surface) exposed to the temperature and humidity environment and one side (non-contact surface) enclosed in the temperature and humidity environment is significantly different. Therefore, how to evaluate the stability of the super-hydrophobicity of the contact surface and non-contact surface of the super-hydrophobic paper-based materials under different application conditions, especially different temperature and humidity environments (because the temperature and humidity of the environment have a greater impact on the physicochemical properties of the paper-based fibers) is a key technical problem that the existing detection method needs to solve. Summary of the invention

[0005] The present invention aims to solve the above problems and provides a method for quantitatively detecting the stability of super-hydrophobic performance of super-hydrophobic paper-based materials. The method can measure super-hydrophobic paper-based materials of different sizes and has high detection accuracy and good reproducibility.

[0006] In order to achieve the above detection purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for quantitatively detecting the super-hydrophobic stability of a super-hydrophobic paper-based material comprises the following specific steps:

[0008] S1: According to the size of the sample to be tested, select a glass sheet of appropriate specifications. The size of the glass sheet should be slightly larger than the sample size;

[0009] S2: Use sealing tape to fix the sample to be tested on the glass sheet, ensuring that the edges of the sample to be tested are sealed with tape and the middle position of the sample to be tested is kept in good contact with the test environment;

[0010] S3: According to the actual application conditions of the super-hydrophobic paper-based sample, the test time is determined, and the test interval is determined according to the test time, and the number of test samples to be prepared is calculated accordingly, that is, the number of glass sheets with the samples to be tested fixed thereon is calculated;

[0011] S4: according to the test requirements, set the temperature and humidity conditions of the constant temperature and humidity chamber, put the prepared samples to be tested into the constant temperature and humidity chamber with the set test conditions, record the initial time t0, and take out the samples to be tested in sequence according to the designed test interval time;

[0012] S5: First, use a contact angle meter to measure the contact angle and rolling angle of the contact surface of the sample to be tested, then slowly remove the sealing waterproof tape to ensure the integrity of the sample to be tested, and use a contact angle meter to measure the contact angle and rolling angle of the non-contact surface of the sample to be tested;

[0013] S6: According to the contact angles of the two surfaces of the super-hydrophobic paper-based sample measured during the entire test cycle, analyze their changing patterns, find out the starting time t1 when the contact angle is less than 150°, and calculate the stabilization time T of the super-hydrophobic performance of the sample s (T s =t1-t0, h) and determine the final stable value of the contact angle θ c (°);

[0014] S7: According to the rolling angle of the super-hydrophobic paper-based sample measured during the entire test cycle, analyze its changing pattern, find the starting time t2 when the rolling angle is greater than 10°, and calculate the rolling lag time T of the super-hydrophobic performance of the sample L (T L = t2-t0, h) and determine the final stable value of the rolling angle θ s (°).

[0015] In the above S1, if the sample is rectangular, the length of the glass sheet is 0.5-10 mm larger than the sample, and the width is 0.5-5 mm larger than the sample; if the sample is square, the side length of the glass sheet is 0.4-11 mm larger than the sample; if the sample is circular, the diameter of the glass sheet is 0.3-6 mm larger than the sample.

[0016] The sealing tape described in S2 above is a special waterproof tape.

[0017] The humidity adjustment range in the above S4 is: 4-98% RH, and the temperature adjustment range is: 5-70°C, wherein any combination of temperature and humidity can constitute the temperature and humidity conditions for testing.

[0018] The benefits of the present invention are as follows: a constant temperature and humidity chamber is used to simulate different actual temperature and humidity conditions; a sealing and waterproof tape is used to seal and fix the sample to be tested on a glass sheet on all sides to simulate the contact surface and non-contact surface of the super-hydrophobic paper-based material; the stability of the super-hydrophobic properties of the contact surface and non-contact surface of the super-hydrophobic paper-based material under different temperature and humidity conditions can be quantitatively detected; the advantages of convenient detection, high measurement accuracy and good reproducibility are achieved; and the present invention is suitable for detecting the stability of the super-hydrophobic properties of super-hydrophobic paper-based samples of various sizes and shapes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] Figure 1 A schematic diagram of a sample preparation method (front view);

[0021] Figure 2 Schematic diagram of a sample preparation method (top view).

[0022] Among them, 1-glass sheet, 2-waterproof sealing tape, 3-contact surface of superhydrophobic paper-based sample, 4-non-contact surface of superhydrophobic paper-based sample. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below through specific embodiments, but this should not be construed as limiting the scope of the present invention to the following embodiments. Without departing from the concept of the above-mentioned detection method of the present invention, various changes or substitutions made according to scientific and technological knowledge and conventional methods and means in the field should be included in the scope of the present invention.

[0024] Embodiment 1 of a method for quantitatively detecting the stability of super-hydrophobic performance of super-hydrophobic paper-based materials of the present invention:

[0025] S1: The shape of the sample to be tested is rectangular, with a length of 30 mm and a width of 25 mm. The length of the glass sheet is 35 mm and the width is 28 mm.

[0026] S2: Use waterproof tape to fix the sample to be tested on the glass sheet, ensure that the edges of the sample to be tested are sealed with waterproof tape, and the middle position of the sample to be tested is kept in good contact with the test environment;

[0027] S3: Determine that the total test time of the super-hydrophobic paper-based sample is 48 hours, the test time interval before 36 hours is 2 hours, and the test time interval after 12 hours is 1 hour. Based on this, it is calculated that 31 test samples need to be prepared;

[0028] S4: Set the temperature and humidity conditions of the constant temperature and humidity chamber to: humidity 75±5% RH, temperature 30±3°C, put the prepared samples to be tested into the constant temperature and humidity chamber with set test conditions, record the initial time t0, and take out the samples to be tested in sequence according to the designed test interval time;

[0029] S6: First, the contact angle and the rolling angle of the contact surface of the samples to be tested (directly exposed to the high temperature and humid environment) are measured by a contact angle meter, and then the sealing and waterproof tape is slowly removed to ensure the integrity of the samples to be tested. The contact angle and the rolling angle of the non-contact surface of the samples to be tested (directly in contact with the glass surface but not directly exposed to the high temperature and humid environment) are measured by a contact angle meter;

[0030] S7: According to the contact angles of the two surfaces of the super-hydrophobic paper-based sample measured during the entire test cycle, analyze their changing patterns, find out the starting time t1 when the contact angle is less than 150°, and calculate the stabilization time T of the super-hydrophobic performance of the sample s (T s =t1-t0, h) and determine the final stable value of the contact angle θ c (°);

[0031] S8: According to the rolling angles of the two sides of the super-hydrophobic paper-based sample measured during the entire test cycle, analyze their changing rules, find out the starting time t2 when the rolling angle is greater than 10°, and calculate the rolling lag time T of the super-hydrophobic performance of the sample L (T L = t2-t0, h) and determine the final stable value of the rolling angle θ s (°).

[0032] Based on the above method, the contact angle and rolling angle of the two surfaces of the super-hydrophobic paper-based sample M change with time as shown in Table 1.

[0033] Table 1 Superhydrophobic performance stability results of superhydrophobic paper-based sample A at humidity 75±5%RH and temperature 30±3℃

[0034]

[0035] Based on Table 1, the stabilization time T of the superhydrophobic performance of the contact surface of superhydrophobic sample A s The contact angle is θ at the end of 39h. c is 139.8°, and the rolling lag time T L The final stable value of the rolling angle is θ s The super hydrophobic performance of the non-contact surface stabilizes for 45 hours, the final stable value of the contact angle is 149.2°, and the rolling hysteresis time T L The final stable value of the rolling angle is θ s It is 12.7°.

[0036] Embodiment 2 of a method for quantitatively detecting the stability of super-hydrophobic performance of super-hydrophobic paper-based materials of the present invention:

[0037] S1: The shape of the sample to be tested is circular with a diameter of 20 mm, and the diameter of the circular glass piece selected is 21 mm;

[0038] S2: Use waterproof tape to fix the sample to be tested on the glass sheet, ensure that the edges of the sample to be tested are sealed with waterproof tape, and the middle position of the sample to be tested is kept in good contact with the test environment;

[0039] S3: Determine that the total test time of the super-hydrophobic paper-based sample is 72 hours, the test time interval before 48 hours is 12 hours, and the test time interval after 48 hours is 6 hours. Based on this, it is calculated that 9 test samples need to be prepared;

[0040] S4: Set the temperature and humidity conditions of the constant temperature and humidity chamber to: humidity 50±5% RH, temperature 20±3°C, put the prepared samples to be tested into the constant temperature and humidity chamber with set test conditions, record the initial time t0, and take out the samples to be tested in sequence according to the designed test interval time;

[0041] S6: First, the contact angle and the rolling angle of the contact surface of the samples to be tested are measured by a contact angle meter, and then the sealing and waterproof tape is slowly removed to ensure the integrity of the samples to be tested, and the contact angle and the rolling angle of the non-contact surface of the samples to be tested are measured by a contact angle meter;

[0042] S7: According to the contact angles of the two surfaces of the super-hydrophobic paper-based sample measured during the entire test cycle, analyze their changing patterns, find out the starting time t1 when the contact angle is less than 150°, and calculate the stabilization time T of the super-hydrophobic performance of the sample s (T s =t1-t0, h) and determine the final stable value of the contact angle θ c (°);

[0043] S8: According to the rolling angles of the two sides of the super-hydrophobic paper-based sample measured during the entire test cycle, analyze their changing rules, find out the starting time t2 when the rolling angle is greater than 10°, and calculate the rolling lag time T of the super-hydrophobic performance of the sample L (T L = t2-t0, h) and determine the final stable value of the rolling angle θ s (°).

[0044] Based on the above method, the contact angle and rolling angle of the two surfaces of the super-hydrophobic paper-based sample M change with time as shown in Table 2.

[0045] Table 2 Superhydrophobic performance stability results of superhydrophobic paper-based sample M at humidity 50±5%RH and temperature 20±3℃

[0046]

[0047] Based on Table 2, the stabilization time T of the superhydrophobic performance of the contact surface of the superhydrophobic sample M s After 48 hours, the final stable value of the contact angle is θ c is 140.0°, rolling lag time T L For 24h, the final stable value of the rolling angle is θ sThe super hydrophobic performance of the non-contact surface stabilizes for >72h, the final stable value of the contact angle is 152.9°, and the rolling hysteresis time T L For >72h, the final stable value of the rolling angle is θ s It should be noted that by extending the test time, the specific stabilization time and rolling hysteresis time of the non-contact surface of the sample can be accurately measured. This embodiment is only for illustrating and explaining the present invention, and will not be described in detail here.

Claims

1. A method for quantitatively detecting the stability of super-hydrophobic performance of super-hydrophobic paper-based materials, characterized in that The specific steps include: S1: According to the size of the sample to be tested, select a glass sheet of appropriate specifications. The size of the glass sheet should be slightly larger than the sample size; S2: Use sealing tape to fix the sample to be tested on the glass sheet, ensuring that the edges of the sample to be tested are sealed with tape and the middle position of the sample to be tested is kept in good contact with the test environment; S3: According to the actual application conditions of the super-hydrophobic paper-based sample, the test time is determined, and the test interval is determined according to the test time, and the number of test samples to be prepared is calculated accordingly, that is, the number of glass sheets with the samples to be tested fixed thereon is calculated; S4: according to the test requirements, set the temperature and humidity conditions of the constant temperature and humidity chamber, put the prepared samples to be tested into the constant temperature and humidity chamber with the set test conditions, record the initial time t0, and take out the samples to be tested in sequence according to the designed test interval time; S5: First, use a contact angle meter to measure the contact angle and rolling angle of the contact surface of the sample to be tested, then slowly remove the sealing waterproof tape to ensure the integrity of the sample to be tested, and use a contact angle meter to measure the contact angle and rolling angle of the non-contact surface of the sample to be tested; S6: According to the contact angles of the two surfaces of the super-hydrophobic paper-based sample measured during the entire test cycle, analyze the variation pattern, find the starting time t1 when the contact angle is less than 150°, calculate the stabilization time Ts (Ts=t1-t0, h) of the super-hydrophobic performance of the sample and determine the final stable value θc (°) of the contact angle; S7: Based on the rolling angle of the superhydrophobic paper-based sample measured during the entire test cycle, analyze its variation pattern, find out the starting time t2 when the rolling angle is greater than 10°, calculate the rolling lag time TL (TL=t2-t0, h) of the superhydrophobic performance of the sample and determine the final stable value θs(°) of the rolling angle.

2. The method for quantitatively detecting the super-hydrophobic performance stability of super-hydrophobic paper-based materials according to claim 1, characterized in that In S1, if the sample is rectangular, the length of the glass sheet is 0.5-10 mm larger than the sample, and the width is 0.5-5 mm larger than the sample; if the sample is square, the side length of the glass sheet is 0.4-11 mm larger than the sample; if the sample is circular, the diameter of the glass sheet is 0.3-6 mm larger than the sample.

3. The method for quantitatively detecting the super-hydrophobic performance stability of super-hydrophobic paper-based materials according to claim 1, characterized in that The sealing tape described in S2 is a special waterproof tape.

4. The method for quantitatively detecting the super-hydrophobic performance stability of super-hydrophobic paper-based materials according to claim 1, characterized in that The humidity adjustment range in S4 is 4-98% RH, and the temperature adjustment range is 5-70° C., wherein any combination of temperature and humidity can constitute the temperature and humidity conditions for testing.

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