CN212483251U - Testing device for molecular membrane layering dynamic adsorption and interface rheology - Google Patents
Testing device for molecular membrane layering dynamic adsorption and interface rheology Download PDFInfo
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Abstract
The utility model discloses a molecular membrane layering developments adsorb and interfacial rheology's testing arrangement belongs to interfacial chemistry analysis test technical field. The device comprises a first quartz glass square sample vessel, a U-shaped needle head, a platinum plate, a second quartz glass square sample vessel, a background lamp, a light softening plate, an analytical balance, a piezoelectric ceramic nano platform, a horizontal adjustment sample stage, an electric control sample lifting platform, a microscope lens, a camera and a pressure sensor, wherein the piezoelectric ceramic nano platform, the horizontal adjustment sample stage and the electric control sample lifting platform are sequentially fixed by fixing screws from top to bottom to form a sample stage and a lifting control system. The utility model discloses the layering dynamic adsorption analysis of the molecular membrane of specially adapted surfactant active and colloidal solution and the survey of interface rheological property have promoted the credibility of analytical accuracy and survey value greatly, and the application industry field is extensive, has high spreading value.
Description
Technical Field
The utility model relates to a molecular membrane layering developments adsorb and interfacial rheology's testing arrangement belongs to interfacial chemistry analysis test technical field.
Background
The platinum plate method (Wilhelmy plate method) was proposed as a classical method in L.Wilhelmy1863 (Ueber di Abhangikeit der Capillaritatates-Constanten des Alkohols von Substanz und Gestalt des benetzlen felter Korpers, von.Ludwig Wilhelmy, Ann.Phys.,119,177(1863) with regard to the dependence of the alcohol capillary constant on the substance and shape of the wetted solid). This method, together with the platinum ring method (DuNouy ring), constitutes the classical method of testing the liquid-gas surface tension or the liquid-liquid interfacial tension on the basis of the weighing principle. By replacing the platinum plate with a solid sample of known wetting perimeter, the contact angle values between the solid-liquid-gas three phases can be tested with known values of liquid surface tension, i.e. the well-known wetting balance or dynamic contact angle techniques. Devices for measuring surface tension, interfacial tension or contact angle using the platinum ring method or the platinum plate method have been commercialized, including companies such as Kruss, Dataphysics, KSV, Cahn, Kyowa, USA KINO, shanghai barron information technology ltd, shanghai morning digital technology ltd, and chengde testing machine factory. From the commercial instrument, its technical characterstic mainly embodies: (1) the method adopts a classical sensor connection structure, namely, a sensor is positioned above an integral structure, and a platinum plate or a platinum ring is connected through a lower hanging weighing hook to finish the test purpose; (2) the algorithm of the surface tension employs a classical algorithm such as a platinum ring method (DuNouy method) using c.huh and s.g.mason or Zuidema & Waters correction and a platinum plate method (σ ═ F/(2 (+). COS θ) using a simple mechanical equation, and when the platinum plate method is used, θ ═ 0 and COS θ ═ 1).
The published patents at home and abroad are very many related to surface tension, and the related principles comprise a weighing method, a maximum bubble method, a drop volume method, a capillary method, a laser method and the like. Among them, the weighing method related to this patent has the most patents, and especially related patents in China have reached nearly 30. The overall view is as follows: (1) improvements to test probes (e.g., plates or rings) include ZL 200620131314.6A LIQUID SURFACE TENSION COEFFICIENT MEASURING APPARATUS, ZL 02246571.5A SURFACE TENSION MEASURING SUSPENSION SHEET, ZL 200910116749.1A LIQUID SURFACE TENSION COEFFICIENT MEASURING APPARATUS, etc.; these patents have no bearing on the technology claimed in this patent and do not affect the novelty of this patent; (2) the improved symmetrical retransmission sensor comprises ZL01216371 liquid interface tensiometer, ZL01254339.X liquid surface tension coefficient determinator, ZL200520039453.1 automatic liquid surface tension detector, ZL 200610054181.1 variable temperature liquid surface tension coefficient determination experimental device, ZL 200620051680.0 automatic liquid surface tension coefficient determinator and ZL 201120020899.5 automatic interface tension coefficient determinator, and the like, and has the innovation points that a torsion wire or an improved torsion wire sensor is adopted, or a new sensor (such as a strain gauge sensor and an analytical balance) is introduced, and the balance does not conflict with the innovative structure (a lifting mechanism is added under the condition of not changing the analytical structure) in the patent, so that the innovativeness of the patent is not influenced; (3) innovations on part structures such as a sample pool temperature control or a sample table and the like comprise ZL02213618.5 sample table for liquid surface tension measurement, ZL200820208896.2 experimental device for measuring liquid surface tension coefficient, ZL201120008560.3 liquid surface tension coefficient measuring device for chemical teaching and the like, and the related innovation points are irrelevant to the patent and do not influence the innovation of the patent; (4) the innovation of the overall structure of the surface tension test comprises ZL 201020159905.0 instruments for testing liquid-gas surface tension and liquid-liquid interface tension by a platinum plate method, ZL 201120065224.2 surface/interface tension meter by a liquid platinum ring method, Japanese patent JP2001099772A surface tension measuring method (Japanese KYOWA manual surface tension meter) and the like, the structures of the patents adopt the connection relation inconsistent with the patents, and the patents do not mention or adopt the technology of the lower edge of a test probe in the movement mode and the test realization mode in the test process, and are completely inconsistent with the structure mode of the patent, so the innovation of the patent is not influenced.
As a method, the platinum Plate method (Wilhelmy Plate method) has performed a better summary analysis in the professional books of interface design of A.I.Rusanov, Physical Chemistry of Surface of Arthur.W.Adamson, and standards of Fundamentals of interface and Colloid Science Vol 3 and Liquid-Fluid interfaces of J.Lyklema, and mainly relates to the improvement of the platinum Plate method such as the Surface treatment technology (corner point roughness treatment) of the platinum Plate method, the vertical problem of the platinum Plate method, the wetting problem of the platinum Plate method, and the like, and the improvement of the test precision and the like. In implementing a surface tension or interfacial tension test method, four techniques are mainly included at present: (1) the contact method (Detachment method) is characterized in that the plate is stopped just after contacting the sample, the buoyancy is considered to be zero, and the surface tension value is calculated to be equal to F/(2 x (+). cos theta) by a simple mechanical method; (2) the classical platinum plate method (max pull) which is characterized in that after the platinum plate is immersed in the sample and then pulled up, the surface tension after the maximum value is obtained is equal to F/(2X (+) cos θ), which is a static surface tension test method and cannot be used for testing surfactants and samples with viscosity in practical applications; (3) zero-buoyancy method, which is characterized in that a platinum plate is continuously immersed into a certain depth of 2mm after contacting the liquid surface, and then the platinum plate is pulled back to 2mm to the height of the liquid surface, wherein the buoyancy is assumed to be zero, the contact angle is assumed to be zero, and the surface tension is equal to F/(2 x (+)) cos theta; (4) immersion depth method characterized in that a platinum plate is forcibly immersed to a certain depth, for example, 1mm, and after correcting the buoyancy value at that height, the surface tension value (Fweight + Fbuoyancy)/(2 + cos. theta.) is calculated by the mechanical platinum plate method. (see: In situ force-balance tensiometry, G.S.Lapham, D.R.Downling, W.W.Schult, Experiments In Fluids 27(1999) 157-166, Springer-Verla, 1999). See the enclosed figure 2. From the above-mentioned methods, the characteristics are that the method used is the platinum plate method under the condition of simple mechanical formula, the contact angle value is assumed to be zero, and the buoyancy of the liquid enclosed by the climbing liquid curved surface to the platinum plate is assumed to be zero. See the basic principle diagram of the platinum plate method in the attached figure 3. In 2005, Shanghai Clontan information technology Limited provided a platinum plate algorithm based on elastic coefficient and Young-Laplace equation correction in developed surface tension meters A201 and A601, but the core technology of the algorithm was that a simple Young-Laplace equation was used in combination with the lever coefficient of an analytical balance or a torsion wire sensor, the height of the liquid was obtained by simple calculation, but the contact angle value was not corrected comprehensively. In specific implementation, the methods do not perform the correction of the thin plate Meniscus Contact Angle (LMCA) or adopt the mode of correcting the fixed value of the lower edge during the correction, and do not perform high-precision effective buoyancy correction, so that the novelty and innovation of the patent are not influenced by the method.
In particular, in 2014, Shanghai Clontian, an analytical balance-based interfacial tension and contact angle testing apparatus and method (patent No. 201410722554.2), attempts were made to correct the objectively existing contact angle values by wetting speed and Young-Laplace equation. This is the first trial correction for immersion height and contact angle values. However, since the liquid wetting speed was extremely high in the lower edge test, it was found by high-speed camera measurement that the wetting time was 0.02 sec, which is a wet time of only 8 sheets of distilled water to a platinum plate at 400 FPS. At present, the data updating speed of the analytical balance is 92 data/second at most, namely, once data is updated in about 0.01 second, only 1-2 data points exist during testing, and the high-precision requirement of changing the wetting speed updating rate and correcting the contact angle value cannot be met.
According to the principle of interfacial chemistry, the Angle between the 3D curved surface of the droplet and the tangent of the solid surface can be regarded as the Contact Angle (Contact Angle) when the droplet is on the solid surface. The contact angle value can be measured by a Young-Laplace equation and an image analysis method, and the corresponding testing technology is an axial symmetry influence analysis method (ADSA). The meniscus between the sheet and the liquid and the surface of the liquid, as mentioned in this patent, is not valid at this point as the definition of the contact angle of a small droplet is given by the volume of liquid being much larger than the volume of the sheet. The meniscus angle at this time was first disclosed in patent No. 201410722554.2, an analytical balance-based interfacial tension and contact angle testing apparatus and method. From the principle of interface chemistry, due to the existence of the surface tension of the solid and the surface tension of the liquid, a clear meniscus arc exists for any solid and liquid contact surface with the volume or the cross-sectional area smaller than that of the liquid. This arc does not coincide with the state at the contact angle (droplet) between solid and liquid. This Meniscus arc of the sheet or fiber within the liquid should be considered the sheet Meniscus Contact Angle (LMCA). The definition of LMCA and solving the equation is not consistent with the definition of the contact angle of a small droplet. Thus, the corresponding contact angles (sheet, fiber, powder, etc.) obtained by the current weighing principle differ in value from the contact angle of an image-wise droplet by an LMCA angle.
The dynamic adsorption phenomenon of molecular membranes currently adopts an interface rheometer adopting an optical imaging method as a mainstream technology. In shanghai barron patent No. 201110244512.9, "method and apparatus for interfacial rheology test by drop imaging method", a method for calculating interfacial elasticity coefficient based on the phase angle deviation between surface area or volume and surface tension or interfacial tension based on the assa algorithm is proposed. However, in practice, due to unpredictability of the adsorption time of the molecular film, the analysis of the time effect based on the change of the oscillation frequency actually causes a problem that the test time is too long and the accuracy of the time effect is not high.
Similar surface tension time effect testing techniques mainly include a maximum bubble pressure method (Max bubble pressure) and a maximum drop volume method (Max volume). Both can only be tested to obtain the fastest reaction time possible for the surfactant (i.e., dead time or life time). The basis of the measured value analysis is a curve of time when the surface tension changes and the corresponding surface tension after the speed is reduced from the fastest speed, and a newly formed interface (a new interface of bubbles and liquid) disappears in each testing process, so that the whole completed dynamic adsorption and the change phenomenon thereof cannot be really tested in practical application. The ringing effect of surfactants as mentioned in this patent is not measurable by the method of the formation of a single new interface.
Another major drawback of shanghai barron, an analytical balance-based interfacial tension and contact angle testing apparatus and method (patent No. 201410722554.2), is that it requires the sensing probe (platinum plate) to be brought into contact with the liquid in advance as it achieves its test surface tension value. At this time, the liquid-gas interface is effectively formed, and although the interface can be slightly changed by lowering or raising the sample stage, the effect of forming a new interface by changing the interface is extremely poor. A sandwich effect surface tension testing device and method based on a weighing principle (patent number: 201910505540.8) and a method and device for detecting milk SDS (sodium dodecyl sulfate) by using a surface tension sandwich effect (patent number: 201611028923.3) respectively provide a measurement of the surface tension or the interface tension of different layers under a static condition based on the weighing principle and an optical principle. For the measurement of properties of molecular membranes, the need for dynamic adsorption is deficient under static conditions.
In the field of academic works at home and abroad (Physical Chemistry of Surface, by arthur.w.adamson, and the principle of action of surfactants, by zhao national seal, pages 105-151), the study of dynamic adsorption of surfactants has been limited to the study of adsorption isotherms of ionic or nonionic surfactants and simple adsorption amounts (different Surface tensions) based on critical micelle concentrations. Studies on dynamic adsorption of deeper-lying surfactants, particularly dynamic adsorption based on the surface or interfacial tension sandwich effect, have not been conducted due to limitations of the test techniques.
The best theoretical model for the dynamic adsorption of surfactants or colloidal solutions lies in: and (3) quickly forming a liquid-gas or liquid-liquid interface, waiting for the dynamic change of the surfactant or the system after forming the new interface, observing the change of the surface tension or the interface tension, and analyzing all dynamic adsorption data. Through the above summary analysis, it can be seen that the traditional platinum plate or platinum ring method cannot effectively form a new interface; the maximum bubble method or the maximum drop volume method cannot effectively maintain the interface and test the final stable value and the dynamic adsorption process. The traditional platinum plate method utilizes the premise that the Contact Angle value of a platinum plate droplet is zero and utilizes the lower edge to measure, and does not carry out high-precision and effective thin plate Meniscus Contact Angle (LMCA) and buoyancy correction, so that the congenital defects exist when the dynamic adsorption of a molecular membrane is tested, and the precision can not meet the requirements.
U.S. Pat. No. 5 FOR MEASURING THE SURFACE tension of THE SURFACE PRESSURE (U.S. Pat. No. US 6,222,184 Bl) proposes a measurement method based on THE principle of platinum plate SURFACE tension test applied to SURFACE PRESSURE, and THE SURFACE tension and THE change curve of THE SURFACE area are realized by changing THE SURFACE area, so that THE method can be used FOR MEASURING THE rheological property of THE interface. However, the change of the surface area is not ideal in speed and change range in the implementation process, and the surface is susceptible to the influence of liquid vibration to cause the change of the surface tension curve. The calculation of surface tension is simply a force measurement analysis without detailed correction of meniscus contact angle and buoyancy. The patent ZL01115539.6 discloses a method and a device for testing rheological properties of an interface as in the patent US 6,222,184 Bl, and the basic principle and technical realization are the same in the two patents. Except that patent ZL01115539.6 details the sample cell. The technical innovation point of the method is that a more scientific and higher-precision correction mode is adopted when the surface tension value is tested; in the measurement of the interface rheological property, a mode of forming and directly changing the meniscus area of the liquid on the thin plate is adopted, and a mode of only changing the surface area of the groove where the liquid is positioned is adopted, obviously, the speed, the precision and the reliability of the former are higher.
By applying the utility model to test the dynamic adsorption of molecular membranes of different ionic surfactants, we obtained the following conclusions:
1. when the anionic surfactant is lower than CMC, the effective components of the surfactant are not easy to adsorb on the liquid-gas interface layer.
2. When the cationic surfactant is lower than CMC, the active ingredients of the surfactant are easy to be adsorbed on the liquid-gas interface layer.
Meanwhile, experimental results show that dynamic change exists in the adsorption process of the surfactant, namely the surfactant is adsorbed to a liquid-gas interface, leaves the liquid-gas interface and is automatically adsorbed back to the liquid-gas interface, and when the concentration of the surfactant is usually lower than the critical micelle concentration, the oscillation process lasts for several or several cycles, and the phenomenon is called as the ringing effect of the dynamic adsorption of the surfactant.
The results of the above studies are not currently available by conventional surface tension testing techniques. The results of these studies are based on the above proposed testing device and method for dynamic adsorption of molecular membrane in a layered manner.
SUMMERY OF THE UTILITY MODEL
The utility model discloses to the problem that above-mentioned background art mentioned, and take following technical scheme to realize:
a testing device for molecular membrane layered dynamic adsorption and interface rheology comprises a first quartz glass square sample vessel, a U-shaped needle head, a platinum plate, a second quartz glass square sample vessel, a background lamp, a light softening plate, an analytical balance, a piezoelectric ceramic nano platform, a horizontal adjustment sample stage, an electric control sample lifting stage, a microscope lens, a camera and a pressure sensor, wherein the piezoelectric ceramic nano platform, the horizontal adjustment sample stage and the electric control sample lifting stage are sequentially fixed by fixing screws from top to bottom to form a sample stage and a lifting control system, the first quartz glass square sample vessel is sleeved inside the second quartz glass square sample vessel, the second quartz glass square sample vessel is arranged at the top of the piezoelectric ceramic nano platform, the U-shaped needle head is arranged in the first quartz glass square sample vessel and communicated with a tee joint, the other end of the tee joint is communicated with the pressure sensor through an air pipe, the platinum plate is also arranged inside the first quartz glass square sample vessel and is connected with the analytical balance through a connecting rod, the background lamp and the light softening plate are respectively positioned on two sides of the first quartz glass square sample vessel, and the microscope and the camera are also distributed on two sides of the first quartz glass square sample vessel.
As a preferable example, the other end of the pressure sensor is connected with a computer for capturing the pressure value of the U-shaped needle in real time.
As a preferred example, the analytical balance is connected with a computer through an RS232 data line or a USB data line, and the stress data on the platinum plate is captured in real time through the computer.
As a preferred example, the backlight and the soft light plate constitute a backlight system, and the micro-lens and the camera constitute an imaging system.
As a preferred example, the upper edge of the U-shaped needle is positioned below the platinum plate.
The utility model has the advantages that: hanging a platinum plate below an analytical balance, and testing a corrected sheet meniscus contact angle and surface tension after buoyancy when the upper edge of the platinum plate is in contact with liquid; after a U-shaped needle is immersed into the liquid to be tested, testing the dynamic surface tension during hanging drop, thereby completing the test of the dynamic adsorption of the molecular membranes of different layers; analyzing the change curve of the surface tension value along with time and the surface area to obtain the dynamic adsorption of the corresponding molecular membrane and the corresponding interfacial elastic coefficient modulus; the method is particularly suitable for the layered dynamic adsorption analysis of the molecular membrane of the surfactant and the colloidal solution, greatly improves the reliability of analysis precision and measured value, has wide application industry field and has high popularization value.
Drawings
FIG. 1: the structure diagram of the molecular membrane dynamic adsorption testing device disclosed by the patent;
in fig. 1: the device comprises a first quartz glass square sample vessel 1, a U-shaped needle 2, a platinum plate 3, a second quartz glass square sample vessel 7, a background lamp 8, a light softening plate 9, an analytical balance 10, a piezoelectric ceramic nano platform 11, a horizontal adjustment sample stage 12, an electric control sample lifting stage 13, a microscope lens 14, a camera 15 and a pressure sensor 16;
FIG. 2: the top view of the sample vessel and the platinum plate structure;
in fig. 2: the device comprises a quartz glass square sample vessel 1, a U-shaped needle 2, a platinum plate 3 and a quartz glass square sample vessel 7;
FIG. 3: a molecular membrane layering dynamic adsorption structure schematic diagram;
in fig. 3: the device comprises a quartz glass square sample vessel 1, a U-shaped needle 2, a platinum plate 3, a liquid meniscus change curve indication 4, a tested liquid 5 and a hanging drop 6; FIG. 4: an LMCA schematic diagram of a platinum gold plate when a sheet meniscus contact angle changes along with the rising height;
in fig. 4: the contact angle of the thin plate meniscus when the platinum plate completely and just contacts the liquid level is 4-1, the contact angle of the thin plate meniscus when the platinum plate completely rises over a small section of liquid level is 4-2, the contact angle of the thin plate meniscus when the platinum plate completely rises over a small section of liquid level is 4-3, and the contact angle of the thin plate meniscus when the platinum plate completely rises and the surface tension climbing height is consistent is 4-4; FIG. 5: the structural schematic diagram of the thin plate meniscus contact angle, platinum plate, buoyancy and climbing liquid;
FIG. 6: a typical stress change curve chart of a platinum plate rising method;
FIG. 7: analysis of the effect of changes in dynamic surface tension of different types of surfactants.
Detailed Description
In order to make the technical means, the creation features, the achievement purposes and the functions of the present invention easy to understand and understand, the present invention is further explained by combining the following specific drawings.
As shown in fig. 1-7, a testing device for molecular membrane layered dynamic adsorption and interface rheology comprises a first quartz glass square sample vessel 1, a U-shaped needle 2, a platinum plate 3, a second quartz glass square sample vessel 7, a background lamp 8, a light softening plate 9, an analytical balance 10, a piezoelectric ceramic nano platform 11, a horizontal adjustment sample stage 12, an electric control sample lifting stage 13, a microscope lens 14, a camera 15, a pressure sensor 16, the piezoelectric ceramic nano platform 11, the horizontal adjustment sample stage 12, and the electric control sample lifting stage 13, which are fixed by fixing screws sequentially from top to bottom to form a sample stage and a lifting control system, wherein the first quartz glass square sample vessel 1 is sleeved inside the second quartz glass square sample vessel 7, the second quartz glass square sample vessel 7 is arranged on top of the piezoelectric ceramic nano platform 11, the U-shaped needle 2 is arranged in the first quartz glass square sample vessel 1, the three-way valve is communicated, the other end of the three-way valve is communicated with the pressure sensor 16 through an air pipe, the platinum plate 3 is also arranged inside the first quartz glass square sample vessel 1 and is connected with the analytical balance 10 through a connecting rod, the background lamp 8 and the light softening plate 9 are respectively positioned at two sides of the first quartz glass square sample vessel 1, and the microscope 14 and the camera 15 are also distributed at two sides of the first quartz glass square sample vessel 1.
The other end of the pressure sensor 16 is connected with a computer for capturing the pressure value of the U-shaped needle 2 in real time.
The analytical balance 10 is connected with a computer through an RS232 data line or a USB data line, and the computer captures the stress data on the platinum plate 3 in real time
When a liquid-gas system is tested, after the first quartz glass square sample vessel 1 is filled with the tested liquid, the first quartz glass square sample vessel is directly placed in the second quartz glass square sample vessel 7, and then the tested liquid is added into the first quartz glass square sample vessel 1 until the liquid overflows;
when a liquid-liquid system is tested, after a high-density phase of a tested liquid is filled in a first quartz glass square sample vessel 1, placing the first quartz glass square sample vessel in a second quartz glass square sample vessel 7, and then adding a low-density phase liquid into the second quartz glass square sample vessel 7; after completion, the first quartz glass square sample vessel 1 was replenished with high density phase liquid until overflow.
The backlight system is composed of the background light 8 and the soft light plate 9, and the imaging system is composed of the micro lens 14 and the camera 15.
And (3) capturing the contact angle value and the rising height of the meniscus of the thin plate in real time through an imaging system, and establishing real-time data relation with the force measurement of the analytical balance 10 and the micro-pressure value of the pressure sensor for final data analysis.
The upper edge of the U-shaped needle head 2 is positioned below the platinum plate 3.
A test method for molecular membrane layering dynamic adsorption and interface rheology comprises the following steps:
s1, sleeving the first quartz glass square sample vessel 1 in the second quartz glass square sample vessel 7, and positioning the upper edge of the U-shaped needle 2 below the platinum plate 3, so that during imaging, an image of a hanging drop on the upper edge of the U-shaped needle and a meniscus curve image of the platinum plate can appear in the camera 15 at the same time;
s2, adopting the way that the platinum plate 3 rises to use the upper edge surface of the platinum plate 3 as a probe test surface, solving the height, the meniscus contact angle value and the surface tension value by utilizing the relation between the height of the liquid climbing process and the meniscus contact angle and the surface tension change, and realizing the rise of the platinum plate 3 relative to the rise of the platinum plate by lowering the electric control sample lifting platform 13; in the process that the platinum plate 3 rises, due to the action of surface tension, the liquid can climb on the surface of the platinum plate 3; when the rising height of the platinum plate 3 is smaller than the maximum value which can be reached by the action of the surface tension of the liquid, the maximum value of the height of the liquid is consistent with the height of the platinum plate 3, and the relationship between the height value, the meniscus contact angle value and the corresponding stress at the moment conforms to the Young-Laplace equation, namely:
wherein, sigma is a surface tension value, theta is a contact angle value, d is a platinum plate thickness, delta rho is a liquid density difference, x is a liquid surface curved surface length, y is a liquid surface curved surface height, h is a climbing height of a liquid surface, g is a gravity system, and R is a gravity system0Analyzing a real-time image to obtain the height of a stress slope change point and a meniscus contact angle value by simultaneously analyzing data of a balance 10 and an imaging system, and calculating to obtain a surface tension value or an interface tension value by utilizing a platinum plate method stress method analysis formula;
Ftotal＝Fplateweight+Fsurfacetension-Fbuoyancy→Ftotal＝mg+σ*2*(w+d)cosΘ-Δρghwd
wherein g is a gravity system, sigma is a surface tension value, d is the thickness of the platinum plate, theta is a contact angle value, delta rho is a liquid density difference, h is a climbing height of the liquid surface, omega is the length of the platinum plate, and m is the weight weighed by an analytical balance;
wherein, the method for solving the Young-Laplace equation adopts an Asha algorithm (ADSA-RealDrop method);
s3, placing distilled water in a first quartz glass square sample vessel 1, obtaining the surface tension value of the distilled water by the traditional platinum plate method measurement to be in accordance with the standard value of the literature, ensuring that the tested liquid, the first quartz glass square sample vessel 1, a second quartz glass square sample vessel 7 and a U-shaped needle 2 are clean, a piezoelectric ceramic nano platform 11, a horizontal adjustment sample stage 12 and an electric control sample lifting stage 13 jointly form a lifting sample stage, completely immersing a platinum plate 3 into the tested sample by the lifting sample stage, stopping lifting the sample stage according to the method when the liquid-liquid interface tension value is tested, placing low-density phase liquid in the second quartz glass square sample vessel 7, finding the highest possible climbing height of the platinum plate 3 in the mode of S2, stopping lifting the sample stage, keeping the position of the platinum plate 3 unchanged, and dropping a surfactant aqueous solution or a diluted surfactant aqueous solution, capturing the test and meniscus contact angle values in real time by a computer and calculating corresponding surface tension or interfacial tension values;
through the method, the analysis of the change effect of the dynamic surface tension of different types of surfactants is realized (figure 7), a special change curve of the surfactants such as SDS is obtained for the first time, the special change curve is called ringing effect, the specific experimental result is shown in figure 7, the SDS (sodium dodecyl sulfate) cationic surfactant has obvious processes of continuous adsorption and separation from top to bottom, which is mainly because the density of the SDS is higher than that of water, and the molecules are easy to sink into the water; however, SDS is a surfactant, and the action mechanism of SDS is a surface layer formed by water and air, so that the adsorption phenomenon can occur; meanwhile, as shown in fig. 7, the adsorption curves of different types of surfactants are different, and the cationic surfactant usually has the phenomenon that the surface tension rapidly decreases and then increases during adsorption; the surface tension of the anionic surfactant is rapidly reduced during adsorption, and then the anionic surfactant is in a descending trend;
the operation method of the dynamic surface tension or the interfacial tension of the pressure method comprises the following steps:
(1) suspending air bubbles or low-density phase liquid at the top end of the U-shaped needle head 2 (under interfacial tension);
(2) when the surfactant aqueous solution is dropped in the platinum sheet method dynamic surface tension or interface tension measuring process, the pressure value and the vertex curvature radius of the pressure sensor 16 are obviously changed, and the high-speed dynamic surface tension or interface tension value is obtained by testing through the height and the vertex curvature radius data of the pressure sensor 16 and the imaging system which are combined, and by utilizing the high sensitivity (usually reaching 0.5ms or less) of the pressure sensor 16;
in addition, from experimental data, the surface tension value or the interfacial tension value (upper layer) of the liquid and the air layer is generally obtained by the dynamic platinum plate method principle of S3, while the surface tension value or the interfacial tension value (sinking into the liquid) of the lower layer is generally obtained by the dynamic surface tension of the pressure method, and the surface tension or the interfacial tension sandwich effect data of the liquid can be analyzed and obtained by combining the two data;
s4, placing distilled water in the first quartz glass square sample vessel 1, and obtaining a surface tension value of the distilled water by the traditional platinum plate method to be in accordance with a standard value of a document, so as to ensure that the tested liquid, the first quartz glass square sample vessel 1, the second quartz glass square sample vessel 7 and the U-shaped probe 2 are clean; the platinum gold plate 3 was completely immersed into the sample to be tested by raising the sample stage. When the liquid-liquid interfacial tension value is tested, low-density phase liquid is placed in the second quartz glass square sample vessel 7; after finding the highest possible climbing height of the platinum plate 3 in the manner of S2, stopping lifting the sample platform, and keeping the position of the platinum plate 3 unchanged; the ascending waveform or the descending waveform, such as sine or sawtooth wave or any waveform change, and the ascending and descending height value (generally, the height is the highest height value of the liquid climbing) of the piezoelectric ceramic nano platform 11 platform are set; reading the height change value and the surface tension change curve value in real time by a computer, and analyzing by using the liquid area (S) and the surface/interface tension value (gamma) and adopting an interface tension relaxation method to obtain the interface expansion elasticity (epsilon)d) And interfacial extensional viscosity (. eta.)d) And the like.
The piezoelectric ceramic nano platform 11 has the function of changing rapidly in a sine or sawtooth wave or any waveform.
Experiments prove that a test device and a test method for molecular membrane layered dynamic adsorption and interface rheology.A thin plate made of platinum is hung below an analytical balance, and the meniscus contact angle of the modified thin plate and the surface tension after buoyancy are tested when the upper edge of the platinum plate is in contact with liquid; after a U-shaped needle is immersed into the liquid to be tested, testing the dynamic surface tension during hanging drop, thereby completing the test of the dynamic adsorption of the molecular membranes of different layers; the dynamic adsorption of the corresponding molecular membrane and the corresponding interfacial elastic coefficient modulus are obtained by analyzing the change curve of the surface tension value along with time and the surface area, the method is particularly suitable for the layered dynamic adsorption analysis of the molecular membrane of the surfactant and the colloidal solution and the determination of the interfacial rheological property, the analysis precision and the reliability of the measured value are greatly improved, the application industry field is wide, and the method has extremely high popularization value.
The basic principles and the main features of the invention and the advantages of the invention have been shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that various changes and modifications may be made without departing from the spirit and scope of the invention, and such changes and modifications fall within the scope of the claimed invention. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (5)
1. A test device for molecular membrane layered dynamic adsorption and interface rheology is characterized in that: the device comprises a first quartz glass square sample vessel, a U-shaped needle, a platinum plate, a second quartz glass square sample vessel, a background lamp, a light softening plate, an analytical balance, a piezoelectric ceramic nano platform, a horizontal adjustment sample stage, an electric control sample lifting stage, a microscope lens, a camera and a pressure sensor, wherein the piezoelectric ceramic nano platform, the horizontal adjustment sample stage and the electric control sample lifting stage are sequentially fixed by fixing screws from top to bottom to form a sample stage and a lifting control system, the first quartz glass square sample vessel is sleeved inside the second quartz glass square sample vessel, the second quartz glass square sample vessel is arranged at the top of the piezoelectric ceramic nano platform, the U-shaped needle is arranged in the first quartz glass square sample vessel and communicated with a tee joint, and the other end of the tee joint is communicated with the pressure sensor through an air pipe, the platinum plate is also arranged inside the first quartz glass square sample vessel and is connected with the analytical balance through a connecting rod, the background lamp and the light softening plate are respectively positioned on two sides of the first quartz glass square sample vessel, and the microscope and the camera are also distributed on two sides of the first quartz glass square sample vessel.
2. The device for testing the layered dynamic adsorption and interfacial rheology of the molecular membrane according to claim 1, wherein: the other end of the pressure sensor is connected with a computer which is used for capturing the pressure value of the U-shaped needle in real time.
3. The device for testing the layered dynamic adsorption and interfacial rheology of the molecular membrane according to claim 2, wherein: the analytical balance is connected with a computer through an RS232 data line or a USB data line, and stress data on the platinum plate is captured in real time through the computer.
4. The device for testing the layered dynamic adsorption and interfacial rheology of the molecular membrane according to claim 1, wherein: the backlight system is composed of the background lamp and the light softening plate, and the imaging system is composed of the micro-lens and the camera.
5. The device for testing the layered dynamic adsorption and interfacial rheology of the molecular membrane according to claim 1, wherein: the upper edge of the U-shaped needle head is positioned below the platinum plate.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114324072A (en) * | 2022-01-17 | 2022-04-12 | 四川大学 | Method for measuring surface tension coefficient of liquid by thin plate method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114324072A (en) * | 2022-01-17 | 2022-04-12 | 四川大学 | Method for measuring surface tension coefficient of liquid by thin plate method |
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