CN110256816A - A kind of compound smart material and its preparation method and application for strain transducer - Google Patents

Abstract

The invention relates to the technical field of road detection devices, in particular to a composite smart material used for strain sensors and its preparation method and application. The composite smart material includes: by weight, 80-120 parts of dual-type resin, 0.5-8 parts of non-metallic carbon material, 5-15 parts of reactive diluent, 30-70 parts of curing agent, 0-0 parts of curing accelerator 4 parts, 5-10 parts of toughening agent and 5-25 parts of dispersant; The dual-type resin is made up of bisphenol A type epoxy resin and novolac epoxy resin; The multi-scale non-metallic carbon material is made of carbon nano tube and carbon black. The composite sensitive material proposed by the invention has many advantages such as high precision, long service life, high survival rate, high temperature resistance (up to 180° C.) and low cost, and is suitable for detecting strain changes of pavement structural layers.

Description

A composite sensitive material for strain sensor and its preparation method and application

technical field

The invention relates to the technical field of road detection devices, in particular to a composite smart material used for strain sensors and its preparation method and application.

Background technique

The information disclosed in the Background of the Invention is only intended to increase the understanding of the general background of the invention, and is not necessarily to be taken as an acknowledgment or any form of suggestion that the information constitutes the prior art that is already known to those skilled in the art.

The construction and working environment of the asphalt concrete pavement structure layer is often relatively harsh, and the commonly used high-precision, high-sensitivity sensors are often not suitable for the harsh environment of road asphalt pavement construction and operation, resulting in extremely low survival rate and poor compatibility with the pavement structure. The small-scale detection accuracy is not enough, and the working life is lower than the service time of the structure and materials. However, although the relatively mature imported resistance strain gauge detection system on the market can effectively detect changes in road surface strain, its price is relatively expensive, about 5000-6000 yuan per piece, and it is difficult to use it on a large scale in scientific research, engineering and future smart road construction. Promote apps.

In recent years, the development of polymer compound composite sensitive materials has provided a new idea for solving the problems of poor deformation coordination and insufficient long-term working performance of strain sensors. Composite smart material is a new type of functional material with self-sensing ability to external factors such as its own force, deformation, temperature, humidity and so on. Composite smart materials usually exhibit the electrical characteristics of semiconductors or conductors, and the resistivity of the material itself is often between that of a good conductor and an insulator, and has a certain degree of electrical conductivity. When the composite smart material is affected by external factors, its conductive properties will change, and it will show the change of the output electrical signal (such as resistance) of the composite smart material on a macroscopic level, so as to establish a certain correlation between the external factors and the electrical signal output by the composite smart material In order to obtain relevant mechanical information such as deformation and force of the measured structure and material. For example, patent document 201810297973.4 discloses a strain sensor for monitoring rutting pressure strain on asphalt pavement and its use method. The strip is made of PET composite smart material; the outside of the electrode needs to be connected to an external line for measurement, and an encapsulation layer is arranged on the outside of the electrode. The sensor has the characteristics of high sensitivity, high reliability and good durability, and can monitor and collect signals at any time with low labor intensity. However, the monitoring performance of the sensor described in this patent needs to be further improved.

Contents of the invention

In view of the above problems, the present invention aims to provide a composite smart material for strain sensors, its preparation method and application. It has been verified by experiments that the composite smart material proposed by the invention has many advantages such as high precision, long service life, high survival rate, high temperature resistance and low cost, and is suitable for detecting strain changes of pavement structural layers.

The first purpose of the present invention is to provide a composite smart material for strain sensors.

The second purpose of the present invention is to provide a method for preparing a composite sensitive material for strain sensors.

The third object of the present invention is to provide a road surface strain detection sensor.

The fourth object of the present invention is to provide the application of the composite smart material for strain sensors.

In order to realize the above-mentioned purpose of the invention, the present invention discloses the following technical solutions:

First of all, the invention discloses a composite smart material for strain sensors, which uses dual-type resins as the matrix, multi-scale non-metallic carbon materials as conductors, compounded active diluent, curing agent, curing accelerator, toughening Agent and dispersant; Wherein, described double-type resin is made up of bisphenol A type epoxy resin and novolac epoxy resin; Described multi-scale non-metallic carbon material is made up of carbon nanotube and carbon black; By weight, The base is 80-120 parts, the non-metallic carbon material is 0.5-8 parts, the reactive diluent is 5-15 parts, the curing agent is 30-70 parts, the curing accelerator is 0-4 parts, and the toughening agent is 5-10 parts and dispersant is 5-25 parts.

As a further technical solution, the mass percentage of the bisphenol A epoxy resin and the novolac epoxy resin is 30:70-50:50.

As a further technical solution, the mass ratio of the carbon nanotubes to the carbon black is 1:5-12.

As a further technical solution, the carbon nanotubes are at least one of single-wall carbon nanotubes, double-wall carbon nanotubes, and multi-wall carbon nanotubes.

As a further technical solution, the specific surface area of the carbon nanotubes is ≥240m ² /g, and the electrical conductivity is ≥160s/cm.

As a further technical solution, the specific surface area of the carbon black is 60-140m ² /g.

As a further technical solution, the reactive diluent is dioxypropylene ethyl ether, glycidyl ether, polyglycidyl ether, propylene oxide butyl ether, propylene oxide phenyl ether, triglycidyl propyl ether one or more of.

As a further technical solution, the curing agent is an acid anhydride or aromatic amine curing agent; for example, the acid anhydride curing agent is tetrahydrophthalic anhydride, dodecyl succinic anhydride, methylcyclohexene tetrahydrophthalic anhydride, One or more of acid dianhydrides; the aromatic amine curing agent is one of 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, m-phenylenediamine or more.

As a further technical solution, the curing accelerator is one of 2, 4, 6 tris (dimethylaminomethyl) phenol (DMP-30), 2-ethyl-4-methylimidazole, bisphenol A or a mixture of several.

As a further technical solution, the dispersant is any one of acetone, N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), and dimethylsulfoxide (DMSO).

As a further technical solution, the toughening agent is silicone resin.

One of the characteristics of the composite smart material of the present invention is: the dual-type resin is used as the matrix, and the dual-type resin matrix can give full play to the advantages of good flexibility of bisphenol A epoxy resin and excellent heat resistance of novolac epoxy resin; therefore, with The dual-type resin is used as the matrix, which helps to improve the heat resistance, mechanical properties and weather resistance of the prepared composite smart material, and prolongs the pot life.

The second characteristic of the composite smart material of the present invention is that the multi-scale non-metallic carbon material composed of carbon nanotubes and carbon black is used as a conductor. The multi-scale conductor uses the synergistic effect of the micron-scale size of carbon black and the nano-scale size of carbon nanotubes to construct a conductive network of a microscopic and nanoscopic dual system. In this conductive network, the carbon black of the microstructure The conductive material plays the dual role of building the conductive network and conducting the contact point, and the carbon nanotube conductive material with the nanoscopic structure acts as the filling part of the conductive network.

Secondly, the present invention discloses a method for preparing the composite smart material for strain sensors, which includes the following steps:

(1) Grinding the multi-scale non-metallic carbon-based conductive material after drying; then adding a dispersant for stirring, and then stirring and ultrasonically dispersing the active diluent to obtain a suspension dispersion of the multi-scale non-metallic carbon-based conductive material;

(2) Add dual-type resins to the suspension dispersion in step (1), and ultrasonically disperse after stirring evenly, then add curing agent, curing accelerator and toughening agent, and vacuum dry the product after stirring evenly. Cured, that is.

As a further technical solution, in step (1), the stirring time is 20-30 min.

As a further technical solution, in step (1), the time for the ultrasonic dispersion is 20-40 min.

As a further technical solution, in step (2), after adding the dual-type resin, the stirring process parameters are: rotating speed 800-3000rpm, time 30-40min.

As a further technical solution, in step (2), the time for the ultrasonic dispersion is 60-180 min.

As a further technical solution, in step (2), the curing method is: firstly cure at 100-120°C for 2-4 hours, then cure at 150-160°C for 1-2 hours, and cool to room temperature to obtain a composite smart Material.

Thirdly, the present invention discloses a road surface strain detection sensor, the material of which includes the composite smart material proposed by the present invention or the composite smart material prepared by the method of the present invention.

It should be noted that although composite smart materials have been used as materials for road surface strain detection sensors, the present invention finds that the development of strain sensors suitable for asphalt concrete roads with composite smart materials as the core needs to meet at least the following conditions:

(1) The strength of the composite smart material is equivalent to that of the corresponding layer structure of asphalt concrete.

(2) During the paving process of asphalt concrete pavement, the temperature of materials such as mixing, paving, and rolling is relatively high, about 130°C-160°C, so the developed composite sensitive material strain sensor should withstand a higher temperature than the above temperature listed.

(3) It is sensitive to the strain and deformation of the road surface, and the monitoring accuracy is high.

(4) It can withstand the harsh environment of the road service operation process.

(5) Compatibility with the road surface is good, and the effect of mutual coordinated deformation and system integration is excellent.

In terms of monitoring performance, the composite smart material developed by the present invention can withstand a temperature of up to 180°C on the one hand, and is completely suitable for high temperature conditions such as mixing and rolling of asphalt concrete pavement during the paving process; on the other hand It can effectively monitor the deformation of the road with high monitoring accuracy and sensitivity; in terms of engineering application and service life, the composite smart material strain sensor developed by the present invention can be effectively applied to the field of road engineering where construction and working environments are often harsh. It matches the rigidity of the asphalt concrete pavement structure layer, has a long service life and a high survival rate; in terms of sensor cost performance, the cost of the composite smart material strain sensor developed by the present invention is controlled within 1,000 yuan per piece, which is the premise of ensuring monitoring accuracy and engineering application The unit price of the sensor is greatly reduced, and it has significant economic and social benefits. Therefore, the composite smart material of the present invention is very suitable for the preparation of road surface strain detection sensors.

Finally, the invention discloses the application of the composite smart material and its sensor in road detection.

Compared with the prior art, the present invention has achieved the following beneficial effects:

(1) The composite sensitive material strain sensor of the present invention can withstand temperatures up to 180°C, and has high monitoring accuracy and sensitivity, can effectively monitor the deformation of the road, and is suitable for mixing, rolling and other temperatures during the paving process of asphalt concrete pavement higher case.

(2) The rigidity of the composite smart material of the present invention matches that of the asphalt concrete pavement structure layer, and has a long service life and a high survival rate; and the unit price of the sensor is greatly reduced under the premise of ensuring monitoring accuracy and engineering application.

Detailed ways

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It should be noted that the terminology used here is only for describing specific embodiments, and is not intended to limit exemplary embodiments according to the present invention. For example, as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, their Indicates the presence of features, steps, operations, means, components and/or combinations thereof.

As mentioned above, although the relatively mature imported resistance strain gauge detection system currently on the market can effectively detect changes in road strain, it is relatively expensive and difficult to be widely used in scientific research, engineering, and future smart road construction. Therefore, the present invention proposes a composite smart material for a strain sensor and a preparation method thereof; the present invention will be further described in conjunction with specific embodiments.

Example 1

A composite smart material for strain sensors and a preparation method thereof, comprising the following steps:

(1) Weigh 2.0 parts of multi-walled carbon nanotubes with a specific surface area of 250m ² /g and a conductivity of 186s/cm, and weigh 16 parts of carbon black with a surface area of 80m ² /g, then dry and grind.

(2) Weigh 6 parts of multi-scale non-metallic carbon-based conductive materials prepared in step (1), add 12 parts of dispersant N-methylpyrrolidone (NMP), and mechanically stir for 30 minutes; then add reactive diluent polyglycidyl ether 8 Parts were ultrasonically dispersed for 20 minutes to prepare a suspension dispersion of multi-scale non-metallic carbon-based conductive materials.

(3) Weigh 40 parts of bisphenol A epoxy resin and 60 parts of novolac epoxy resin, add them to the suspension dispersion prepared in step (2), stir mechanically for 30 minutes (rotating speed 2000 rpm), and disperse ultrasonically for 60 minutes.

(4) After ultrasonic dispersion, add 35 parts of curing agent tetrahydrophthalic anhydride, 3 parts of curing accelerator DMP-303 and 7 parts of toughening agent silicone resin, and stir for 5 minutes; after completion, pour the sample into the mold.

(5) Place the poured body obtained in step (4) in a vacuum drying oven to dry for 6 hours. Take out the cast body, put it in a 110°C electric blast drying oven for high temperature curing for 4 hours, then put it in a 150°C electric blast drying oven for high temperature curing for 2 hours, and then demould.

Example 2

A composite smart material for strain sensors and a preparation method thereof, comprising the following steps:

(1) Weigh 2.0 parts of multi-walled carbon nanotubes with a specific surface area of 250m ² /g and a conductivity of 186s/cm, and weigh 10 parts of carbon black with a surface area of 60m ² /g, then dry and grind.

(2) Weigh 0.5 parts of the multi-scale non-metallic carbon-based conductive material prepared in step (1), add 25 parts of dispersant N,N-dimethylformamide (DMF), stir mechanically for 30 minutes; then add reactive diluent II 5 parts of propylene oxide ethyl ether were ultrasonically dispersed for 20 minutes to prepare a suspension dispersion of multi-scale non-metallic carbon conductive materials.

(3) Weigh 51.5 parts of bisphenol A epoxy resin and 68.5 parts of novolac epoxy resin, add them to the suspension dispersion prepared in step (2), stir mechanically for 35 minutes (3000 rpm), and disperse ultrasonically for 100 minutes.

(4) After ultrasonic dispersion, add 30 parts of curing agent dodecyl succinic anhydride, 4 parts of curing accelerator bisphenol A and 10 parts of toughening agent silicone resin, and stir for 5 minutes; after completion, pour the sample into the mold.

(5) Place the poured body obtained in step (4) in a vacuum drying oven to dry for 6 hours. Take out the casting body, put it in a 100°C electric blast drying oven for high temperature curing for 4 hours, then put it in a 155°C electric blast drying oven for high temperature curing for 2 hours, and then demould.

Example 3

A composite smart material for strain sensors and a preparation method thereof, comprising the following steps:

(1) Weigh 2.0 parts of multi-walled carbon nanotubes with a specific surface area of 250m ² /g and a conductivity of 186 s/cm, and weigh 20 parts of carbon black with a surface area of 120m ² /g, then dry and grind.

(2) Weigh 7 parts of multi-scale non-metallic carbon-based conductive materials prepared in step (1), add 10 parts of dispersant dimethyl sulfoxide (DMSO), and stir mechanically for 20 minutes; then add reactive diluent propylene oxide butyl 15 parts of ether, ultrasonically dispersed for 30 minutes to prepare a suspension dispersion of multi-scale non-metallic carbon conductive materials.

(3) Weigh 60 parts of bisphenol-A epoxy resin and 40 parts of novolac epoxy resin, add them to the suspension dispersion prepared in step (2), stir mechanically for 40 minutes (speed 800 rpm), and disperse ultrasonically for 120 minutes.

(4) After ultrasonic dispersion, add 70 parts of curing agent methylcyclohexene tetra-acid dianhydride, 2 parts of curing accelerator 2-ethyl-4-methylimidazole and 8 parts of toughening agent silicone resin, and stir for 5 minutes ; After completion, pour the sample into the mold.

(5) Place the poured body obtained in step (4) in a vacuum drying oven to dry for 6 hours. Take out the casting body, put it in a 120°C electric blast drying oven for high temperature curing for 2 hours, then put it in a 160°C electric blast drying oven for high temperature curing for 1 hour, and then demould.

Example 4

A composite smart material for strain sensors and a preparation method thereof, comprising the following steps:

(1) Weigh 2.0 parts of multi-walled carbon nanotubes with a specific surface area of 250m ² /g and a conductivity of 186s/cm, weigh 24 parts of carbon black with a surface area of 140m ² /g, and then dry and grind them.

(2) Weigh 8 parts of the multi-scale non-metallic carbon-based conductive material prepared in step (1), add 5 parts of dispersant acetone, and mechanically stir for 25 minutes; then add 15 parts of reactive diluent triglyceride propyl ether, and ultrasonically disperse After 40 minutes, a multi-scale non-metallic carbon-based conductive material suspension dispersion was prepared.

(3) Weigh 40 parts of bisphenol A epoxy resin and 40 parts of novolak epoxy resin, add them to the suspension dispersion prepared in step (2), stir mechanically for 35 minutes (rotating speed 2500 rpm), and disperse ultrasonically for 180 minutes.

(4) After the ultrasonic dispersion is completed, add 70 parts of curing agent 4,4'-diaminodiphenylmethane and 5 parts of toughening agent silicone resin, and stir for 5 minutes; after completion, pour the sample into the mold.

(5) Place the poured body obtained in step (4) in a vacuum drying oven to dry for 6 hours. Take out the casting body, put it in a 115°C electric blast drying oven for high temperature curing for 3 hours, then put it in a 150°C electric blast drying oven for high temperature curing for 1.5 hours, and then release the mold.

Performance Testing:

(1) The mechanical and temperature resistance properties of the composite smart material prepared in the above examples were tested, and the results are shown in Table 1.

Example 1 Example 2 Example 3 Example 4 Tensile strength/MPa 68 64 71 73 Elastic modulus/MPa 1250 1183 1296 1194 Temperature limit/℃ 180 173 177 182

It can be seen that the composite intelligent material developed by the present invention has good tensile strength and elastic modulus, can match the rigidity of the asphalt concrete pavement structure layer, has a long service life and a high survival rate; meanwhile, the composite intelligent material developed by the present invention The temperature resistance limit reaches 180°C, which is completely suitable for the high temperature conditions of 130°C-160°C during the mixing and rolling of asphalt concrete pavement during the paving process, and can be adapted to the field of road engineering where the construction and working environment are relatively harsh.

(2) Test the strain monitoring accuracy of the composite smart material prepared in the above embodiment, and the results show that in the range of 0-10000με, the resistance has a clear trend of change with the strain.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A composite smart material for strain sensors, characterized in that, with dual-type resin as matrix, multi-scale non-metallic carbon material as conductor, compound reactive diluent, curing agent, curing accelerator, toughening Agent and dispersant; Wherein, described double-type resin is made up of bisphenol A type epoxy resin and novolac epoxy resin; Described multi-scale non-metallic carbon material is made up of carbon nanotube and carbon black; By weight, The base is 80-120 parts, the non-metallic carbon material is 0.5-8 parts, the reactive diluent is 5-15 parts, the curing agent is 30-70 parts, the curing accelerator is 0-4 parts, and the toughening agent is 5-10 parts and dispersant is 5-25 parts. 2. the composite smart material for strain sensor as claimed in claim 1, is characterized in that, the mass percent of described bisphenol A type epoxy resin and novolac epoxy resin is 30:70-50:50. 3. The composite sensitive material for strain sensor as claimed in claim 1, characterized in that, the mass ratio of the carbon nanotubes and carbon black is: 1:5-12; Preferably, the carbon nanotubes are at least one of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes; Preferably, the specific surface area of the carbon nanotubes is ≥240m ² /g, and the electrical conductivity is ≥160s/cm; Preferably, the specific surface area of the carbon black is 60-140m ² /g. 4. the composite sensitive material for strain sensor as described in any one of claim 1-3, it is characterized in that, described reactive diluent is dioxypropylene ethyl ether, glycidyl ether, polyglycidyl ether, One or more of propylene oxide butyl ether, propylene oxide phenyl ether, and triglyceride propyl ether; Preferably, the curing agent is an acid anhydride or aromatic amine curing agent; for example, the acid anhydride curing agent is tetrahydrophthalic anhydride, dodecyl succinic anhydride, methylcyclohexene tetra-acid dianhydride One or more of; the aromatic amine curing agent is one or more of 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, m-phenylenediamine . 5. the composite sensitive material for strain sensor as described in any one of claim 1-3, it is characterized in that, described curing accelerator is 2,4,6 three (dimethylaminomethyl) phenol (DMP- 30), a mixture of one or more of 2-ethyl-4-methylimidazole and bisphenol A; Preferably, the dispersant is any one of acetone, N-methylpyrrolidone, N,N-dimethylformamide, and dimethyl sulfoxide; Preferably, the toughening agent is silicone resin. 6. A preparation method for a composite sensitive material for a strain sensor, characterized in that, comprising the steps: (1) Grinding the multi-scale non-metallic carbon-based conductive material after drying; then adding a dispersant for stirring, and then stirring and ultrasonically dispersing the active diluent to obtain a suspension dispersion of the multi-scale non-metallic carbon-based conductive material; (2) Add dual-type resins to the suspension dispersion in step (1), and ultrasonically disperse after stirring evenly, then add curing agent, curing accelerator and toughening agent, and vacuum dry the product after stirring evenly. Cured, that is. 7. the preparation method of the composite sensitive material for strain sensor as claimed in claim 6, is characterized in that, in step (1), described stirring time 20-30min; Preferably, in step (1), the ultrasonic dispersion time is 20-40min. 8. The preparation method of the composite sensitive material for strain sensor as claimed in claim 6 or 7, it is characterized in that, in step (2), after adding dual-type resin, the stirring process parameters are: rotating speed 800-3000rpm, time 30 -40min; Preferably, in step (2), the time of the ultrasonic dispersion is 60-180min; Preferably, in step (2), the curing method is: firstly curing at 100-120° C. for 2-4 hours, then curing at 150-160° C. for 1-2 hours, and cooling to room temperature to obtain a composite smart material. 9. A road surface strain detection sensor, characterized in that the material of the sensor comprises the composite smart material according to any one of claims 1-5 and/or the composite material prepared by the method according to any one of claims 6-8 Astute material. 10. The composite smart material prepared by the method according to any one of claims 1-5 and/or the method according to any one of claims 6-8 and/or the sensor according to claim 9 detects on the road in the application.