CN102183441B - Method for measuring surface adhesive capacity and elastic modulus of soft material - Google Patents

Abstract

The invention discloses a method for measuring the surface adhesive capacity and an elastic modulus of a soft material, the method comprises the following specific steps of: (1) preparing a sample and selecting a probe according the physical property and the chemical property of a tested sample; (2) controlling a horizontal substrate and the spherical probe to move oppositely to be contacted and separated at a constant speed; (3) measuring an interaction force P, a relative displacement delta and a contact radius a respectively by using a pressure sensor, a displacement sensor and an optical microscope in the whole process of the step (2) when the substrate and the probe are contacted with each other; (4) frequently repeating the steps (2) and (3) under the control of software; and (5) quantitatively analyzing the adhesive capacity and the elastic performance of the tested material by using data obtained in the step (3) according to a jabatan kerja raya (JKR) theory. The measurement method has giant application potential in the aspects of scientific research on soft materials such as high-molecule elastic body, biogel and the like, product quality control in industrial manufacturing processes and the like.

Description

A kind of surface adhesion ability of soft material and the measuring method of elastic modulus

Technical field

The present invention relates to a kind of to the surface adhesion ability of soft material and the measuring method of elastic modulus.

Background technology

Surperficial viscoelastic measurement to soft materials such as macromolecular elastomer and xanthan gels is an important field of research always.When two articles contacts, having adhesion produces; For object than rigidity; Owing to be not easy to take place the influence that therefore deformation can ignore adhesion; And receiving external force to produce deformation usually easily for the soft material of low elastic modulus, it is very important that the adhesion of this moment will become, and it measured accurately also become very important.

Applied to Johnson among the present invention; Theoretical (the K. L. Johnson of the JKR that Kendall and Roberts set forth in 1971; K. Kendall, A. D. Roberts, Proc. R. Soc. London A; 1971 the 324th volume 301-313 pages or leaves), and quantitative description the adhesion that produces when being in contact with one another of perfect elastic body and the balance between the elastic potential energy.The JKR theory had after the people such as Shull and further developed.

Common has " flow measurement method " and " peel strength mensuration " to the viscoelastic measuring method of soft material." flow measurement method " is to characterize its rheological property through the variation of soft material being sheared and measuring shearing force, can be realized by business-like flow graph usually." peel strength mensuration " is the size that required power is come the exosyndrome material adhesion when measuring material and peel off with the stiff base of adhering to; Chinese patent " viscosity measurement method of the film " (patent publication No.: CN101192505) of for example applying at Wu Han; Utilize laminator job platform uniform motion that film to be measured and rubber strip are peeled off, read the viscosity measurement result of tautness meter reading as film to be measured.First method only is confined to the flowing material of low modulus is measured, and can not characterize the more elastic body or the soft material of high-modulus, and the surface adhesion of energy measurement material not.Second kind can not characterize the elastic modulus of material, and test is that destructive and required sample size is bigger.

Summary of the invention

In view of above problem; The object of the present invention is to provide a kind of to the surface adhesion ability of soft material and the measuring method of elastic modulus; This method can be simultaneously characterizes the elastic modulus and the adhesion energy of soft material, and only needs the sample of micro-volume during test.For solving the problems of the technologies described above, the application has developed a kind of based on JKR theoretical quantitative measurment and the surface adhesion ability of analyzing soft material and the method for elastic modulus, and particular content is following:

The measuring method of a kind of soft material surface adhesion ability and elastic modulus comprises the steps:

(1) carries out the preparation of specimen and the selection of probe according to the physics and the chemical property of sample;

(2) horizontal substrate of said specimen and said probe are at the uniform velocity to be in contact with one another and to separate;

Interaction force P, relative displacement δ and contact radius a when (3) in the whole process of step (2), measuring said horizontal substrate respectively simultaneously and contact with said probe with pressure transducer, displacement transducer and optical microscope;

(4) the optional majority of step (2) time repetition under control of software;

(5) utilize the data that obtain in the step (3), according to the adhesion energy and the elastic modulus of the said specimen of the theoretical quantitative test of JKR.

Said horizontal substrate and said probe vertically carry out move toward one another with speed 1～40 μ m/s continuously under computer and Stepping Motor Control; Said horizontal substrate contacts and forms the circular contact area that a said contact radius is a with said probe; Vertical direction acting force between said horizontal substrate and the said probe is said interaction force P; Said horizontal substrate is δ with relative displacement after said probe contacts, and said then horizontal substrate is carried out reverse motions until separating with said probe with identical speed.

Said specimen is processed smooth elastic film A and is attached to transparent substrates, and the thickness of film A is h, the rigid inorganic probe of corresponding selection sphere or spherical crown shape or rigid metal probe;

The radius of said sphere or spherical crown shape is R, and it is m that sphere can plate macromolecule material film B and thickness as required equably.

Said macromolecule material film B is a high molecular film material;

The thickness h of said macromolecule material film B>> δ>m, and a/ δ>1/2;

Said specimen also can be made into the elasticity probe of spherical crown shape, and corresponding horizontal substrate is the planar rigidity material, and can plate macromolecule material film C and thickness as required uniformly is n;

Said planar rigidity material is microslide or the silicon chip or the gold-plated silicon chip of cleaning, uses after can being cut into the square small pieces of 10mmx10mm;

The thickness h of said macromolecule membrane C>> δ>n, and a/ δ>1/2;

The spherical radius of the elasticity probe of said spherical crown shape is R, and the bottom surface radius is r, and height is h.

Said optical microscope is transparent unilateral observation and the said surface of contact radius a of record from said horizontal substrate and said probe.

The theoretical quantitative Analysis elastic modulus E of utilization JKR ^*With energyreleaserate G, comprise following two steps:

(1) calculating elastic modulus E ^*

Through data a, δ and the P that records, can calculate elastic modulus E according to formula (1) ^*Work as a<<during h, available formula (2) approximate treatment elastic modulus E ^*:

；

(2) calculating energy rate of release G

Energyreleaserate G reflection testee surface adhesion performance size, G is big more, and body surface viscosity is more little, on the contrary the wisp surface viscosity is big more more for G;

When obtaining elastic modulus E ^*After, can calculate energyreleaserate G through formula group I or II:

。

Said soft material is macromolecular elastomer, gel or film.

Said macromolecule material film B and C can select material different according to test request.As need measuring samples and the adhesion energy of specifying polymer surface, then select this kind macromolecular material; The adhesion energy of measuring samples and hydrophobic surface is generally selected polymethylmethacrylate, polystyrene, teflon etc. for use; The adhesion energy of measuring samples and water-wetted surface is generally selected polyacrylic acid, polyvinyl alcohol (PVA), polyamide etc. for use.

Compare with prior art, the present invention has the following advantages: the test material that is suitable for is extensive, comprises soft materials such as macromolecular elastomer, gel, film; Can be simultaneously the elastic modulus and the adhesion energy of soft material be characterized; Measuring accuracy is high; Stability and good reproducibility; And the sample volume that needs during test is little.

Description of drawings

Fig. 1 is the geometric parameter synoptic diagram of each parts in the viscoelasticity measurement experiment of the present invention; The physical dimension synoptic diagram of wherein, (a) popping one's head in for elasticity; (b) be rigid probe synoptic diagram among the embodiment 1;

Fig. 2 is the power-displacement curve and corresponding MIcrosope image that records gel among the embodiment 1; Wherein ordinate is acting force P, and horizontal ordinate is relative displacement δ;

Fig. 3 is three cyclic force-displacement curves that record gel among the embodiment 2.

Embodiment

Through embodiment the present invention is specifically described below.Be necessary to be pointed out that at this; Following examples only are used for the present invention is described further; Can not be interpreted as the restriction to protection domain of the present invention, some nonessential improvement and adjustment that the professional and technical personnel in this field content according to the present invention is made still belong to protection scope of the present invention.

The measurement of the power-displacement curve of embodiment 1 gel

Fig. 1 (a) is the physical dimension synoptic diagram of elasticity probe, and spherical radius is R, and the bottom surface radius is r, and height be h, and is fixed on elasticity on the rigid tray and pops one's head in and contact with stiff base, and the surface of contact radius is a, and perpendicular to substrate direction generation deformation δ; (b) be middle rigid probe synoptic diagram, for rigid probe presses down attached to the elastic film on the stiff base, vertical substrate direction volume under pressure is δ.Shown in Fig. 1 (b); Thick h is that the circle self-control gel of 10mm sticks on the microslide with 502 glue for the 4mm radius; Microslide speed with 10 little meter per seconds under Stepping Motor Control presses down the stainless shot that radius R is 3 ± 0.001mm; Depression distance δ is 50 microns, leaves steel ball with identical speed then and until breaking away from fully.Fig. 2 is the power-displacement curve of gel and the MIcrosope image of 5 instantaneous correspondences wherein; Dark circular region in 5 width of cloth MIcrosope images is the surface of contact of steel ball and gel; Through measuring its radius a size and combining corresponding pressure value P; The energyreleaserate G of formula group I quantitative Analysis gel capable of using when elastic modulus E * is known, big or small in this instance because of not measuring a value, so do not make quantitative Analysis.Can make qualitative and quantitative analysis to the viscoelasticity of material in conjunction with Fig. 2.Fig. 2 curve horizontal ordinate is the displacement δ of steel ball, and ordinate is pressure and the pulling force that steel ball receives, and can judge the viscosity size of material according to the area of tensile region, and the big more tack of materials of area is big more when δ is identical.

The measurement of three cyclic force-displacement curves of embodiment 2 gels

Same shown in Fig. 1 (b); Thick h is that the circle self-control gel of 10mm sticks on the microslide with 502 glue for the 4mm radius; Speed with 10 little meter per seconds under Stepping Motor Control presses down the stainless shot that radius R is 3 ± 0.001mm; Depression distance δ is 50 microns, leaves steel ball with identical speed then and until breaking away from fully, and repeats above process and obtain the result that three circulations are measured.Fig. 3 is the cyclic force-displacement curve of gel.Shown in figure, O1, O2 and O3 are respectively 1; Pulling force 0 point in 2,3 tests, the viscous deformation that can analyze material from 3 positions is big or small; O2 and O1 have big distance; Tangible viscous deformation has taken place in explanation material in the 2nd test, and O3 and O2 position are more or less the same, and illustrative material in the 3rd test viscous deformation does not take place basically.

Claims (6)

1. A soft material surface adhesion can and the measuring method of elastic modulus, it is characterized in that, comprise the steps:

   (1) carries out the preparation of specimen and the selection of probe according to the physics and the chemical property of specimen;

   (2) horizontal substrate of said specimen and said probe are at the uniform velocity to be in contact with one another and to separate;

   Interaction force P, relative displacement δ and contact radius a when (3) in the whole process of step (2), measuring said horizontal substrate respectively simultaneously and contact with said probe with pressure transducer, displacement transducer and optical microscope;

   (4) the optional majority of step (2) time repetition under control of software;

   (5) utilize the data that obtain in the step (3), according to the adhesion energy and the elastic modulus of the said specimen of the theoretical quantitative test of JKR;

   Said horizontal substrate and said probe vertically carry out move toward one another with speed 1～40 μ m/s continuously under computer and Stepping Motor Control; Said horizontal substrate contacts and forms the circular contact area that a said contact radius is a with said probe; Vertical direction acting force between said horizontal substrate and the said probe is said interaction force P; Said horizontal substrate is δ with relative displacement after said probe contacts, and said then horizontal substrate is carried out reverse motions until separating with said probe with identical speed;

   One of following two kinds of methods are chosen in the preparation of said specimen:

   A) said specimen is processed smooth elastic film A and is attached to transparent substrates, and the thickness of film A is h, the rigid inorganic probe of corresponding selection sphere or spherical crown shape or rigid metal probe; The radius of said sphere or spherical crown shape is R, and plating thickness equably is the macromolecule material film B of m; The thickness h of said macromolecule material film B>> δ>m, and a/ δ>1/2;

   B) said specimen is processed the elasticity probe of spherical crown shape, and corresponding horizontal substrate is the planar rigidity material; Said planar rigidity material is microslide or the silicon chip or the gold-plated silicon chip of cleaning, and plating thickness equably is the macromolecule material film C of n; The thickness h of said macromolecule material film C>> δ>n, and a/ δ>1/2.
2. 2. measuring method according to claim 1 is characterized in that, the spherical radius of the elasticity probe of said spherical crown shape is R, and the bottom surface radius is r, and height is h.
3. 3. measuring method according to claim 1 is characterized in that, said optical microscope is transparent unilateral observation and the said contact radius a of record from said horizontal substrate and said probe.
4. 4. according to claim 1 or 3 described measuring methods, it is characterized in that the theoretical quantitative Analysis elastic modulus E of utilization JKR ^*With energyreleaserate G, comprise following two steps:

   (1) calculating elastic modulus E ^*

   Through data a, δ and the P that records, can calculate elastic modulus E according to formula (1) ^*Work as a<<during h, with formula (2) approximate treatment elastic modulus E ^*:

   $\mathrm{\&delta;}=\frac{a^2}{R}[0.4+0.6{\exp }^{(-18a/h)}]+\frac{{[1+1.33(a/h)+1.33{(a/h)}^3]}^{-1}}{2E^{*}a}(P-\frac{4E^{*}{a}^3}{3R})---\left(1\right);$

   $\mathrm{\&delta;}=\frac{a^2}{3R}+\frac{P}{2E^{*}a}---\left(2\right)$

   (2) calculating energy rate of release G

   When obtaining elastic modulus E ^*After, calculate energyreleaserate G through formula group I or II:

   $I\left\{\begin{array}{cc}G=\frac{{(P^{\&prime;}-P)}^2}{8\mathrm{\&pi;}{E}^{*}{a}^3}\left(\frac{0.56+1.5(a/h)+3{(a/h)}^3}{{(0.75+(a/h)+{(a/h)}^3)}^2}\right)& \left(3\right)\\ P^{\&prime;}=\frac{4E^{*}{a}^3}{3R}& \left(4\right)\end{array}\right..$

   $\mathrm{II}\left\{\begin{array}{cc}G=\frac{E^{*}{({\mathrm{\&delta;}}^{\&prime;}-\mathrm{\&delta;})}^2}{2\mathrm{\&pi;a}}[1+2.67\left(\frac{a}{h}\right)+5.33{\left(\frac{a}{h}\right)}^3]& \left(5\right)\\ {\mathrm{\&delta;}}^{\&prime;}=\frac{a^2}{R}[0.4+0.6{\exp }^{(-18a/h)}]& \left(6\right)\end{array}\right.$
5. 5. measuring method according to claim 1 is characterized in that, said soft material is macromolecular elastomer, gel or film.
6. 6. measuring method according to claim 1; It is characterized in that; When measuring said specimen and specifying the adhesion energy of polymer surface, the material of said macromolecule material film B and said macromolecule material film C is identical with said appointment macromolecular material; When measuring the adhesion energy of said specimen and hydrophobic surface, said macromolecule material film B and said macromolecule material film C are polymethylmethacrylate, polystyrene or teflon; When measuring the adhesion energy of said specimen and water-wetted surface, said macromolecule material film B and said macromolecule material film C are polyacrylic acid, polyvinyl alcohol (PVA) or polyamide.

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