CN111440443A

CN111440443A - Preparation method of isotropic electrorheological elastomer and detection method of vibration absorption performance of electrorheological elastomer

Info

Publication number: CN111440443A
Application number: CN202010148797.5A
Authority: CN
Inventors: 巫金波; 袁欣; 温维佳; 周雪峰; 张萌颖; 薛厂
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2020-03-05
Filing date: 2020-03-05
Publication date: 2020-07-24
Anticipated expiration: 2040-03-05
Also published as: CN111440443B

Abstract

The invention provides a preparation method of an isotropic electrorheological elastomer, which comprises the steps of adding electrorheological particles into PDMS prepolymer or a mixed solution of PDMS prepolymer and silicone oil, stirring to uniformly disperse the electrorheological particles, adding a curing agent, stirring until the curing agent is uniformly mixed to obtain a sizing material, transferring the sizing material into a container, removing bubbles in a vacuum environment, and curing in an oven to obtain the isotropic electrorheological elastomer. The invention also provides a method for detecting the vibration absorption performance of the prepared electrorheological elastomer. The preparation method of the electrorheological elastomer has simple process, does not need a curing electric field, does not need to provide a high-voltage power supply and design a corresponding pressurizing and curing die, can reduce the preparation cost, and the prepared electrorheological elastomer also has larger storage modulus variation and higher relative ER effect.

Description

Preparation method of isotropic electrorheological elastomer and detection method of vibration absorption performance of electrorheological elastomer

Technical Field

The invention relates to the technical field of electrorheological material preparation, in particular to a preparation method of an isotropic electrorheological elastomer, and simultaneously, the invention also relates to a method for detecting the vibration absorption performance of the prepared electrorheological elastomer.

Background

The electrorheological elastomer is composed of high molecular polymer (such as rubber) and dielectric particles with a micro-nano scale, and can be generally divided into an anisotropic electrorheological elastomer and an isotropic electrorheological elastomer, wherein the isotropic electrorheological elastomer is prepared by performing a curing process under a condition without an electric field, the orientation of the electrorheological particles is randomly distributed, so that an isotropic material is obtained, the anisotropic electrorheological elastomer is prepared by performing a curing process under a certain electric field, the electrorheological particles are polarized under the electric field to form chains, columns and other structures, and the ordered structures are locked after the curing is completed, so that the anisotropic material is obtained.

Compared with the anisotropic electrorheological elastomer, the isotropic electrorheological elastomer has the characteristics of simple preparation and easy large-scale production, and is more suitable for popularization and application. However, the anisotropic electrorheological elastomer applied at present also has the problems of small variation of storage modulus and low relative ER effect (electrorheological effect), the variation of the storage modulus is only higher than 400kPa, the relative ER effect is generally lower than 5, and the practical application of the electrorheological elastomer is limited to a great extent.

Disclosure of Invention

In view of this, the present invention is directed to a method for preparing an isotropic electrorheological elastomer, so as to prepare an isotropic electrorheological elastomer.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a method for preparing an isotropic electrorheological elastomer, and the method comprises the following steps:

a. adding the electrorheological particles into PDMS prepolymer or the mixed solution of PDMS prepolymer and silicone oil, and stirring to uniformly disperse the electrorheological particles;

b. adding a curing agent, and stirring until the curing agent is uniformly mixed to obtain a sizing material;

c. and transferring the rubber material into a container, removing bubbles in a vacuum environment, and curing in an oven to obtain the isotropic electrorheological elastomer.

Furthermore, the electrorheological particles adopt giant electrorheological particles BaTiO (C)₂O₄)₂+NH₂CONH₂。

Further, when a mixed solution of the PDMS prepolymer and the silicone oil is adopted, the mass ratio of the PDMS prepolymer to the silicone oil is 0-1.

Further, the silicone oil is dimethyl silicone oil.

Further, the viscosity of the dimethyl silicone oil is 5-100 mpas.

Furthermore, the addition amount of the electrorheological particles accounts for 10-50% of the total weight of the electrorheological elastomer.

Further, when only the PDMS prepolymer is used, the addition amount of the electrorheological particles is 10 to 45 wt.%, and when a mixed solution of the PDMS prepolymer and the silicone oil is used, the addition amount of the electrorheological particles is 10 to 50 wt.%.

Further, the curing agent adopts a silicon-hydrogen crosslinking agent, and the addition amount of the curing agent is 10-20 wt.% of the PDMS prepolymer.

Further, the curing temperature in the oven is 50-80 ℃.

Compared with the prior art, the invention has the following advantages:

the preparation method of the isotropic electrorheological elastomer can prepare the isotropic electrorheological elastomer by gradually mixing the electrorheological particles, the PDMS prepolymer or the mixed solution of the PDMS prepolymer and the silicone oil and the curing agent and curing the mixture in an oven. The preparation method has simple process, does not need a curing electric field, does not need to provide a high-voltage power supply and design a corresponding pressurizing and curing die, and can reduce the preparation cost and the safety risk of the electrorheological elastomer.

Meanwhile, in the preparation method, the dispersed phase particles are giant electrorheological particles, the isotropic electrorheological elastomer with excellent performance can be obtained by utilizing the GER effect of the giant electrorheological particles, and the addition of the silicone oil can soften the matrix, so that the performance of the electrorheological elastomer can be further improved.

In addition, the invention also provides a method for detecting the vibration absorption performance of the electrorheological elastomer, which is used for detecting the vibration absorption performance of the electrorheological elastomer prepared above and comprises the following steps:

s1. adhering the electrorheological elastomer on the shaking table, arranging electrodes on both sides of the electrorheological elastomer, placing a detection object on the electrorheological elastomer, adhering the detection object by the electrorheological elastomer, and making a colored mark on the top of the detection object;

s2, adjacent to the electrorheological elastomer, rigidly connecting a reference object for detection on the shaking table, and making a colored mark on the top of the reference object for detection;

s3. connecting the electrode with power supply, and collecting the motion state of the colored mark on the top of the object and reference object to obtain the motion track of the colored mark;

in step s3, a camera is used for shooting, and the exposure time of the camera is 1.0s, so as to obtain the motion trail; alternatively, in step s3, the camera is used to capture the image, and the motion trajectory is obtained by recording a series of positions of the colored mark frame by frame and connecting the series of positions by a curve.

The detection method can realize the detection of the vibration absorption performance of the electrorheological elastomer, and is favorable for judging the performance of the prepared electrorheological elastomer.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a graph of Δ G' of B-PDMS ERE according to the mass fraction of ERE (the top left insert in the graph is the appearance of elastomer);

FIG. 2 is a graph of the relative ER effect of a B-PDMS ERE as a function of the mass fraction of the ERs in accordance with an embodiment of the present invention;

FIG. 3 is a diagram illustrating the relationship between the mass fraction of electrorheological particles and the shear stress of a B-PDMS precursor according to an embodiment of the present invention;

FIG. 4 is a graph of the mass fraction of electrorheological particles versus the viscosity (apparent viscosity) of a B-PDMS precursor according to an embodiment of the present invention;

FIG. 5 is a graph of Δ G' of B-S-PDMS ERE versus the mass fraction of electrorheological particles in accordance with an embodiment of the present invention;

FIG. 6 is a SEM image of B-PDMS ERE (a) and B-S-PDMS ERE (B) according to an embodiment of the present invention;

FIG. 7 is a graph of Δ G' versus electric field for a B-S-PDMS ERE in accordance with an embodiment of the present invention;

FIG. 8 is a graph of Δ G' versus electric field for a B-S-PDMS precursor and a B-S-PDMS ERE according to an embodiment of the present invention (points in the graph are test data, lines are fitted curves);

FIG. 9 is a graph of the relationship between the ER effect and the electric field for the B-S-PDMS ERE according to the embodiment of the present invention;

FIG. 10 is a schematic diagram of the arrangement of B-S-PDMS precursor, B-S-PDMS and B-PDMS under the electric field according to the embodiment of the present invention;

FIG. 11 is a graph illustrating the time response of the storage modulus of a B-S-PDMS ERE in accordance with an embodiment of the present invention;

FIG. 12 is a schematic diagram of the time stability of a B-S-PDMS ERE according to an embodiment of the present invention;

FIG. 13 is a schematic diagram of an apparatus for detecting vibration absorption and energy absorption according to an embodiment of the present invention;

FIG. 14 is a graph showing the comparison of the movement traces of the colored marks on two detection objects in the presence or absence of an electric field;

FIG. 15 is a diagram showing the stress state and microstructure of an elastomer during the detection process;

FIG. 16 is a graph showing the rate of change of the amplitude of a colored mark on a test object with an electric field;

FIG. 17 is a schematic diagram showing the variation of the amplitude of the trace of the colored mark on the object for detection with the electric field (the solid line is the electric field recorded by the high voltage power supply, and the dotted line is the electric field controlled by the square wave);

FIG. 18 shows the variation of the moving trace of the colored mark on the object for detection when the square wave electric field is changed from 0 to 1.5kV/mm during the detection.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

The embodiment relates to a preparation method of an isotropic electrorheological elastomer, which specifically comprises the following steps:

step a: adding the electrorheological particles into PDMS prepolymer or the mixed solution of PDMS prepolymer and silicone oil, and stirring to uniformly disperse the electrorheological particles;

step b: adding a curing agent, and stirring until the curing agent is uniformly mixed to obtain a sizing material; and the number of the first and second groups,

step c: and transferring the rubber material into a container, removing bubbles in a vacuum environment, and curing in an oven to obtain the isotropic electrorheological elastomer.

In the above preparation method, the electrorheological particles used may be GER particles with high electrorheological effect, and are preferably giant electrorheological particles BaTiO (C2O4)2+ NH2CONH2, and the giant electrorheological particles may be referred to as BTRU hereinafter. The silicone oil can then preferably be a dimethicone oil having a viscosity of between 5 and 100mpas, and can be, for example, 5mpas, 10mpas, 20mpas, 25mpas, 50mpas or 75mpas, and it is preferably 10 mpas.

In the present embodiment, when a mixture of PDMS prepolymer and silicone oil is used, it should be noted that the mass ratio between the PDMS prepolymer and the silicone oil may be between 0 and 1, and for example, the ratio between the PDMS prepolymer and the silicone oil may be 1: 5. 1: 4. 1: 3. 1: 2 or 1:1, and the ratio between the two is preferably also 1: 1.

in addition, the addition amount of the electrorheological particles added in the embodiment accounts for 10 to 50% of the total weight of the prepared electrorheological elastomer, and may be, for example, 10 wt.%, 15 wt.%, 18 wt.%, 20 wt.%, 22 wt.%, 25 wt.%, 30 wt.%, 32 wt.%, 35 wt.%, 38 wt.%, 40 wt.%, 42 wt.%, 45 wt.%, 50 wt.%. Moreover, as a preferred embodiment form, when only the PDMS prepolymer is used, the addition amount of the electrorheological particles in this embodiment may be selected to be between 10 and 45 wt.%, and when a mixed solution of the PDMS prepolymer and the silicone oil is used, since more particles may be accommodated at this time, the addition amount of the electrorheological particles may be selected to be between 10 and 50 wt.%.

In this embodiment, the curing agent may generally adopt a hydrosilation cross-linking agent, which is a hydrosilation-terminated siloxane or a hydrosilation-terminated polysiloxane cross-linking agent, and has a chain extension effect, and can generate a silica gel layer with a self-adhesion function under the action of an organosilicon catalyst. In this embodiment, no matter which specific silicon hydride crosslinking agent is selected, it has no influence on the technical effect of this embodiment, and as a preferable example, the curing agent of this embodiment may be specifically selected to be a silicon hydride crosslinking agent containing a platinum catalyst. Meanwhile, the curing agent is generally added in the present embodiment in 10-20 wt.% of the PDMS prepolymer, and may be, for example, 10%, 10.5%, 11%, 12%, 12.5%, 15%, 18%, or 20%. The addition amount of the curing agent affects the curing time, so the specific addition amount can be adjusted according to the need, and the addition amount of the curing agent in this embodiment is preferably 10%.

In the present embodiment, in the above-mentioned curing of the rubber compound, the curing temperature in the oven is generally 50 ℃ to 80 ℃, and may be, for example, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 68 ℃, 70 ℃, 75 ℃ or 80 ℃, and preferably 60 ℃. The curing time in the oven is generally 2 to 8 hours and may be, for example, 2 hours, 2.5 hours, 3 hours, 4 hours, 4.5 hours or 5 hours, 6 hours, 6.5 hours, 7 hours, 8 hours. The curing time can affect the initial modulus of the prepared electrorheological elastomer, and the curing time in actual implementation can be selected according to the specific application of the electrorheological elastomer.

Through the above preparation method, the embodiment can prepare the isotropic electrorheological elastomer, wherein the electrorheological elastomer prepared in the embodiment may also be different based on using a separate PDMS prepolymer or using a mixed solution of the PDMS prepolymer and the silicone oil. At this time, for the preparation example using only the PDMS prepolymer, a BTRU/PDMS isotropic electrorheological elastomer was prepared and may be referred to as a B-PDMS ERE hereinafter, and for the preparation example using a mixed liquid of the PDMS prepolymer and the silicone oil, a BTRU/silicone oil-PDMS isotropic electrorheological elastomer was prepared and may be referred to as a B-S-PDMS ERE hereinafter.

The preparation method of the embodiment can prepare the isotropic electrorheological elastomer, and meanwhile, the isotropic electrorheological elastomer can be prepared only by gradually mixing the raw materials and curing the raw materials in the oven.

The following description will be further described with reference to specific tests on the preparation of the isotropic electrorheological elastomer of the present embodiment, and the following description will be first described with reference to B-PDMS ERE and B-S-PDMS ERE, respectively, according to two preparation examples included in the preparation method.

In this case, it should be noted that, in the preparation of the electrorheological elastomer, the process parameters may generally adopt the respective preferred values, and the curing time in the oven may all adopt the same value. Meanwhile, the following test conditions for testing the storage modulus variation and the relative ER effect are also specifically: the shear strain is fixed at 0.01%, and the angular frequency is 1-100 rad/s.

For B-PDMS ERE

In this example, the mass fraction of the electrorheological particles is increased by 5 wt.% to prepare a plurality of electrorheological elastomers such as PDMS, B-PDMS-5, B-PDMS-10, B-PDMS-15, B-PDMS-20, B-PDMS-25, B-PDMS-30, B-PDMS-35, B-PDMS-40, B-PDMS-45, and B-PDMS-50. Wherein, the first PDMS shows that no electrorheological particles are added, namely B-PDMS-0, and the number behind each B-PDMS represents the mass fraction of the added electrorheological particles, namely the specific gravity of the electrorheological particles in the prepared electrorheological elastomer.

In each of the prepared electrorheological elastomers B-PDMS, the B-PDMS-5 is abandoned because the glue viscosity is low and the electrorheological particles are deposited at the bottom. The electrorheological elastomer prepared in this embodiment may be prepared in different shapes, different sizes, and different thicknesses according to the requirement, and may be specifically as shown in the insert in fig. 1. In addition, it should be noted that the inventor finds that the prepared electrorheological elastomer can be cut into a plurality of pieces by cutting the electrorheological elastomer, and the cut and separated pieces can be re-integrated into one piece, which shows that the electrorheological elastomer of the embodiment has good self-healing property.

The viscoelastic property of the prepared electrorheological elastomer was tested by oscillatory scan test, and fig. 1 shows the change Δ G '(Δ G' ═ G) of the storage modulus of the electrorheological elastomer B-PDMS_E’-G₀', wherein G_E' is the storage modulus under electric field, G₀' storage modulus in the absence of an electric field). The change of the mass fraction of the current-variable particles, namely the concentration of the particles. As can be seen from fig. 1, Δ G 'is very small when the mass fraction of the electro-rheological particles is low, but Δ G' increases sharply with an increase in the concentration of the electro-rheological particles because the distance between the particles decreases when the content of the electro-rheological particles increases, and the electrostatic attraction between the particles is essentially a short distance force, whereby the storage modulus increases rapidly. The higher the mass fraction of the electrorheological particles, the greater the chance of forming chains among the particles, so that under the action of an external electric field, the longer and denser the structure of the particles is, thereby promoting an energy storage modeThe amount is increased.

In addition, as shown in fig. 1, for example, at an electric field of 3kV/mm, when the mass fraction of the erf is less than 45%, Δ G 'increases with the increase of the erf content and reaches a maximum value at 45%, and then Δ G' decreases with the increase of the erf content. The reason for this is that when too many electrorheological particles are added, agglomeration of the dispersed phase may be caused, and even phase separation from the polymer matrix, i.e., PDMS, may occur, thereby adversely affecting the polarization of the electrorheological particles, so that too high content of electrorheological particles may cause poor dispersion state or phase non-uniformity, as is the case with the prepared B-PDMS-50.

The reason for the Δ G' decrease after 45% above can be confirmed by the test of the rheological data of the uncured electrorheological elastomer precursor in fig. 3 and 4. As can be seen from fig. 3 and 4, as the BTRU content increases, the viscosity of the B-PDMS precursor increases, the shear thinning phenomenon is more obvious, and when the mass fraction of the electrorheological particles is 50 wt.%, the fluidity of the corresponding precursor is poor, and further, the performance of the cured electrorheological elastomer is poor.

In this embodiment, the relative ER effect of the prepared B-PDMS along with the change of the mass fraction of the electrorheological particles is shown in fig. 2, and it can be seen from fig. 2 that the change trend is consistent with Δ G' in fig. 1, that is, at a fixed concentration of the electrorheological particles, the relative ER effect increases along with the increase of the electric field strength. At the same electric field strength, the relative ER effect increases with increasing concentration of the electrorheological particles and decreases after reaching the maximum value.

In addition, as shown in FIG. 2 and FIG. 1, the variation of the storage modulus of the prepared B-PDMS is based on the maximum electric field of 3kV/mm, and the performances of the prepared B-PDMS are better to be B-PDMS-40, B-PDMS-45 and B-PDMS-50, and the variation of the storage modulus of the three is larger and is close to 200 kPa. Meanwhile, the relative ER effect of the three is the largest at an electric field strength of 3kV/mm, and the inventor finds that the relative ER effect is respectively 3.71, 3.96 and 3.58.

(II) for B-S-PDMS ERE

In this embodiment, dimethyl silicone oil with a viscosity of 10mPas is specifically used as the silicone oil, the ratio of PDMS to the dimethyl silicone oil is 1:1, and the mass fractions of the electrorheological particles are 40 wt.%, 45 wt.%, and 50 wt.%, respectively, to prepare B-S-PDMSERE.

At this time, the relationship between the storage modulus variation Δ G 'and the mass fraction of the ERE in the prepared B-S-PDMS is shown in FIG. 5, and it can be found that Δ G' increases with the mass fraction of the ERE regardless of high and low electric fields, which is different from the BTRU/PDMS system. This is true because the addition of the dimethylsilicone fluid reduces the agglomeration of the nano-sized electrorheological particles in the PDMS matrix, improving particle dispersion and compatibility of the particles with the matrix, so that in this case, the matrix can support the electrorheological particle content of 50 wt.% without the previous overfilling phenomenon. As shown in FIG. 6, which is an SEM image of a B-PDMS-50ERE cross-section at the left side (a), it can be seen that it appears as more particle agglomeration, while in contrast, FIG. 6, which is an SEM image of a B-S-PDMS-50ERE cross-section at the right side (B), it can be seen that it appears as a uniform distribution of particles, the difference between the two being just justified by the above explanation.

It should be noted that, in addition to reducing the agglomeration of the electrorheological particles in the PDMS, another function of the added silicone oil is to improve the mobility of the electrorheological particles. At this time, FIG. 7 shows the relationship between Δ G' and the electric field intensity, and it can be seen from FIG. 7 that the change of the storage modulus of the B-S-PDMS ERE is large, and the inventors found that the change of the storage modulus of the B-S-PDMS ERE under the electric field of 3kV/mm can reach 396 kPa. At the same time, the inventors have also found that in the range of 0 to 3kV/mm, Δ G' follows the following proportional relationship: Δ G'. varies.. E^αThat is Δ G' is proportional to E^α。

It should be noted that, for the above proportional relation, the inventor also found that the value of the proportionality index α is greater than 2, which is clearly contradictory to the conventional concept, because according to the classical theory, the electrostatic interaction between two dipole particles is proportional to the square of the applied electric field, and Δ G' is related to the electric field strength twice.

For this reason, by measuring Δ G' of the uncured B-S-PDMS precursor under the same test parameters, as shown in fig. 8, it can be found that the test results are consistent with the above judgment. The main reason why there is no linear relationship after the precursor is cured into an elastomer is that the mobility of the electrorheological particles changes.

Generally, the electrorheological particles, whether in dispersion or in isotropic elastomers, are initially randomly distributed and need to migrate in the presence of an electric field in order to conform to the electric field. Because the electrorheological particles in the electrorheological elastomer are locked in the matrix, the mobility of the electrorheological particles is far lower than that of the precursor, and under the condition of low electric field intensity, the electrostatic force among the electrorheological particles is very small, the elastic force of the matrix is difficult to overcome, so that the increment of the storage modulus of the elastomer is very small. When the electric field is large enough, the sum of the electrostatic interactions between the electrorheological particles is larger than the storage modulus of the matrix, and the mobility of the electrorheological particles increases with the increase of the electric field, so the Δ G' value increases rapidly, and the curve of the elastomer in fig. 8 also turns to the curve of the precursor under the high electric field.

It is for the above reasons that Δ G' of B-S-PDMS ERE is in a curve relationship with the electric field, and the higher the mobility of the electrorheological particles, the larger the proportionality coefficient α, and if it is assumed that the particles in the electric field have no mobility at all, then their relationship with the electric field will be shown by the dashed line in fig. 8. furthermore, in this embodiment, the relative ER effect value of B-S-PDMSERE is specifically shown in fig. 9 at different electric field strengths, and as can be seen from fig. 9, the relative ER effect of B-S-PDMS ERE increases with the increase of the field strength, and at 3kV/mm, the relative ER effect of B-S-PDMS ERE with the mass fractions of 40 wt.%, 45 wt.%, and 50 wt.% increases by 24 times, 30 times, and 33 times, respectively.

It should be further illustrated in this embodiment that the difference between the shear modulus and the energy consumption of the electrorheological elastomer B-PDMS ERE and the B-S-PDMS ERE is also due to the addition of the silicone oil, so that the fluidity of the electrorheological particles is increased. At this time, the viscoelastic differences of the B-PDMS ERE and the B-S-PDMS ERE are compared in table 1 below, and the data shows that the storage modulus G 'value of the B-S-PDMS ERE is lower than the G' value of the B-PDMS ERE under the condition of zero field and the same mass fraction of the electrorheological particles, which indicates that the silicone oil can effectively reduce the molecular interaction of the elastomer matrix, thereby reducing the initial storage modulus of the composite material.

After the electric field is applied, the storage modulus G 'and the loss modulus G' of the B-S-PDMS ERE are both rapidly increased and finally exceed the B-PDMS ERE, which shows that the viscosity of PDMS can be greatly reduced by adding the silicone oil, and further the resistance of the electrorheological particles to move can be reduced.

TABLE 1 comparison of viscoelasticity of B-PDMSERE and B-S-PDMS ERE

In the embodiment, the arrangement forms of the electrorheological particles of the B-S-PDMS precursor, the B-S-PDMS ERE, and the B-PDMS ERE under the electric field are shown in fig. 10, in the B-S-PDMS system, the electrostatic interaction easily overcomes the elasticity of the polymer, so that the electrorheological particles have a larger mobility, and thus the electrorheological particles are more easily formed into chains or even columnar structures under the action of the electric field, and meanwhile, the silicone oil also helps the electrorheological particles to be mutually attached to form a compact microstructure in the direction of the electric field, and the effect is more obvious under the action of a high electric field. Therefore, the B-PDMS ERE prepared in this example has a larger storage modulus induced by the electric field, and the increase in particle mobility also results in greater friction, and is manifested as an increase in loss modulus.

With the switching of the electric field, the storage modulus and the loss modulus of the electrorheological elastomer of the embodiment can be almost reversibly changed, and the elastomer can be restored to the initial non-powered state by dissipating the absorbed energy, so that the electrorheological effect is realized. Meanwhile, as mentioned above, the low zero-field modulus and the high electric-field modulus also greatly enhance the relative ER effect of the B-PDMS-ERE of the present embodiment, so that the B-PDMS-ERE has a high practical application value.

In this embodiment, FIG. 11 shows the time response of B-S-PDMS-50 under different electric field strength, in which the electric field is turned on and off alternately, and it can be seen from FIG. 11 that G' responds instantaneously when the electric field is applied, and the B-S-PDMS-50 is nearly reversible at each electric field strength, but as the electric field is larger, the network structure is more firm, and therefore more time is required to return to the initial state.

FIG. 12 shows the time-dependent change of the electrorheological property of B-S-PDMS-50 under the action of an electric field of 2kV/mm, and it can be known from FIG. 12 that the relative ER effect gradually weakens with the time-dependent increase, and when the using time reaches 45d, the relative ER effect decays to 85.3% of the initial value. It can be seen that Δ G' and Δ G "of the B-S-PDMS-50 prepared in this example did not decrease greatly within 45 days, even slightly increase, and the decrease of the ER effect was only a result of the increase of the initial modulus, and the increase of the electric field induced modulus did not decay therewith, thus indicating that the prepared electrorheological elastomer has good time stability.

The same tests and analyses were carried out on the prepared B-S-PDMS-40 and B-S-PDMS-45 except for the B-S-PDMS-50, and the results were similar to those of the B-S-PDMS-50, so that the B-S-PDMS ERE prepared in this example has excellent properties.

(III) verification of vibration damping Performance

To further illustrate the advantages of the isotropic electrorheological elastomer prepared by the preparation method of this embodiment, the following example also specifically takes the prepared B-S-PDMS ERE as an example, and the vibration absorption performance of the prepared electrorheological elastomer is detected, so that the detection can show the effect that the electrorheological elastomer prepared in this embodiment can possess in practical application.

At this time, specifically, the detection method for the vibration absorption performance of the electrorheological elastomer of the embodiment includes the following steps:

step s 1: adhering an electrorheological elastomer on a shaking table, arranging electrodes on two sides of the electrorheological elastomer, placing an object for detection on the electrorheological elastomer, adhering the object for detection by depending on the property of the electrorheological elastomer, and making a colored mark on the top of the object for detection;

step s 2: the device is adjacent to the electrorheological elastomer, a reference object for detection is rigidly connected to the shaking table, and a colored mark is made on the top of the reference object for detection;

step s 3: and connecting the electrode with a power supply, and carrying out image acquisition on the motion states of the colored marks on the tops of the object for detection and the reference object for detection so as to obtain the motion track of the colored marks.

As shown in fig. 13, for the detection object and the detection reference object in the above detection method, two common circular empty bottles may be used, for example, the body of the bottle may be transparent, and the cap may be black, for example, and in this case, the colored mark on the top of the object may be a white mark disposed in the center of the top of the cap, for example. Therefore, the motion state of the mark can be better acquired through the obvious contrast between the black color and the white color.

In addition, as a detection method of the above detection method, in the above step s3, the camera may be used to capture the image, and the exposure time of the camera is 1.0s, so as to obtain the motion trajectory. Alternatively, as another detection method of the above detection method, in step s3 of this embodiment, a camera may be used to capture images, and a series of positions of the colored marks may be recorded frame by frame, and the series of positions may be connected by a curve to obtain the motion trajectory.

In the present embodiment, the two detection methods are simultaneously adopted in the specific detection, so as to better reflect the properties of the prepared electrorheological elastomer.

At this time, for photographing with a camera, the motion state of the mark is acquired by the camera photographing, and as can be seen from fig. 14, after the electric field is applied, the motion radius of the mark is reduced and the change process is also reversible. The above phenomenon can be explained by the process shown in fig. 15, specifically, in the circular motion, the elastic body always generates shear strain due to the force applied to the upper and lower surfaces, and the direction thereof also changes at any time, which is specifically shown in the middle six top views of fig. 15.

When no electric field is applied (E ═ 0), the elastomer is relatively soft and is easily deformed by the driving of the rocking bed, and θ is generated₁So that the motion trajectory of the marker is larger than the trajectory of the rocking platform. Under the application of an electric field (E)>0) When the shear storage modulus of the elastomer is increased, namely the electrorheological particles in the elastomer begin to attract each other, so that chain segments which are approximately parallel to the direction of an electric field are generated to block the next instant shear, and the shear strain is changed into theta₂(θ₁>θ₂) Thereby gradually reducing the motion trajectory. When the electric field is removed, the motion tracks of the elastic body and the mark gradually return to the previous state.

As shown in fig. 16, by varying the electric field intensity, the inventors found that the rate of change of the amplitude radius of the mark on the object for detection can be reversibly adjusted between 0% and 18%. In addition, as shown in fig. 17, by applying a square wave electric field of 1.5kV/mm to the elastic body, the inventors also found that the amplitude of the motion trace of the mark is changed back and forth between 10.6mm and 8.8mm as the electric field is switched, which indicates that the elastic body is changed reversibly as the electric field is switched.

In addition, for the shooting by the camera, as described above, the inventor obtained a series of positions of the marker on the object for detection by the camera frame by frame recording, and connected them by a curve to obtain the motion trajectory change process of the marker when the square wave electric field is changed from 0 to 1.5kV/mm as shown in fig. 18. In fig. 18, from point 1 to point 9, the motion trajectory is a closed ellipse, and the 10 th point begins to deviate inward, which shows that under the action of the electric field, the storage modulus of the elastic body increases and the trajectory shrinks. And when the 29 th point is reached, the motion track is closed, and the whole system returns to the initial position.

For the motion trail of the marker photographed above, the time interval based on every two frames of the camera is 20ms, so that the whole change process can be completed within 0.6S by calculation, thereby also showing that the regulation and control of the B-S-PDMSERE prepared in the embodiment on the motion trail of the marker is fast and reversible, i.e. the response of the elastomer is fast.

The preparation method of the electrorheological elastomer of the embodiment can prepare the isotropic electrorheological elastomer, and the prepared isotropic electrorheological elastomer has excellent performance, can be widely applied to vibration isolation and damping of automobiles, aviation, buildings, precision equipment and the like, and the fields of intelligent execution mechanisms such as electric and artificial muscles, and can be made into different shapes, sizes and thicknesses according to needs, thereby being beneficial to popularization and industrialization and having good practicability.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A preparation method of isotropic electrorheological elastomer is characterized in that: the preparation method comprises the following steps:

2. The method of preparing an electrorheological isotropic elastomer according to claim 1, wherein: the electrorheological particles adopt giant electrorheological particles BaTiO (C)₂O₄)₂+NH₂CONH₂。

3. The method of preparing an electrorheological isotropic elastomer according to claim 1, wherein: when the mixed liquid of the PDMS prepolymer and the silicone oil is adopted, the mass ratio of the PDMS prepolymer to the silicone oil is 0-1.

4. The method of preparing an electrorheological isotropic elastomer according to claim 3, wherein: the silicone oil is dimethyl silicone oil.

5. The method of preparing an electrorheological isotropic elastomer according to claim 4, wherein the electrorheological elastomer is prepared by: the viscosity of the dimethyl silicone oil is 5-100 mpas.

6. The method of preparing an electrorheological isotropic elastomer according to claim 1, wherein: the addition amount of the electrorheological particles accounts for 10-50% of the total weight of the electrorheological elastomer.

7. The method of preparing an electrorheological isotropic elastomer according to claim 6, wherein: when only PDMS prepolymer is adopted, the addition amount of the electrorheological particles is between 10 and 45 wt.%, and when a mixed liquid of PDMS prepolymer and silicone oil is adopted, the addition amount of the electrorheological particles is between 10 and 50 wt.%.

8. The method of preparing an electrorheological isotropic elastomer according to claim 1, wherein: the curing agent adopts a silicon-hydrogen crosslinking agent, and the addition amount of the curing agent is 10-20 wt% of the PDMS prepolymer.

9. The method of preparing an electrorheological isotropic elastomer according to any one of claims 1 to 8, wherein: the curing temperature in the oven is 50-80 ℃.

10. A method for detecting vibration absorption performance of an electrorheological elastomer is characterized by comprising the following steps: the method for detecting the vibration absorption performance of an electrorheological elastomer prepared according to claim 1, and the method comprises the following steps: