LU503175B1

LU503175B1 - Micro tensile strain monitoring sensor and preparation method thereof

Info

Publication number: LU503175B1
Application number: LU503175A
Authority: LU
Inventors: Rui Zhao; Shengtao Zhang; Ning Zhang; Ming Liang; Zhaoming Chi
Original assignee: Univ Shandong; Shandong Hi Speed Group Co Ltd
Priority date: 2022-12-12
Filing date: 2022-12-12
Publication date: 2023-06-12

Abstract

The invention provides a micro tensile strain monitoring sensor and a preparation method thereof. The sensor includes a main structure, a conductive electrode and an encapsulation layer, wherein the main structure comprises a resin polymer matrix, a multi-scale non-metallic carbon conductor, a compound toughening agent, a coupling agent, a curing agent, a curing accelerator and a dispersant; the outer side of the main structure is provided with an encapsulation layer, and at least two ends of the main structure are respectively provided with a conductive electrode extending to the outer side of the encapsulation layer. The sensor can be effectively applied to the road engineering field where the construction and working environment are often harsh, and its rigidity is matched with that of the asphalt concrete pavement structure layer, so that it has long service life and high survival rate, and the unit price of the sensor is greatly reduced on the premise of ensuring the monitoring accuracy and engineering application.

Description

MICRO TENSILE STRAIN MONITORING SENSOR AND 00817

PREPARATION METHOD THEREOF

TECHNICAL FIELD

The invention belongs to the field of road engineering materials, and particularly relates to a micro tensile strain monitoring sensor and a preparation method thereof.

BACKGROUND

The statements in this part only provide background information related to this disclosure, and do not necessarily constitute prior art.

Pavement disease has always been a key technical problem that puzzles the construction and management of road engineering. "Specifications For Design Of

Highway Asphalt Pavement" clearly puts forward that pavement structural strain is the key technical index of pavement structural design, and the deformation of asphalt pavement under periodic wheel load will directly affect the permanent deformation and fatigue cracking of asphalt pavement.

In the process of pavement service, real-time and accurate monitoring of pavement deformation and other indicators can provide scientific basis for construction and maintenance scheme design, construction safety and quality control, health monitoring and comprehensive information control, so as to avoid the increase of maintenance cost, engineering waste and other social and environmental problems caused by early structural damage.

Under the normal operation condition, the tensile strain of asphalt pavement surface and base is often lower than 100*10-6. The tiny deformation poses a great challenge to the monitoring accuracy and sensors. However, the construction and working environment of asphalt concrete pavement structure layer is often harsh.

Commonly used high-precision and high-sensitivity sensors are not suitable for road asphalt pavement construction, have poor compatibility with pavement structure, have insufficient detection accuracy in a small range, and have a working life shorter than that in the harsh environment during the operation process, resulting in extremely low survival rate, service life of structures and materials, etc. Although the mature 7508175 imported resistance strain gauge detection system on the market can effectively detect the pavement strain change, its price 1s too expensive to be widely applied in scientific research, engineering and future intelligent road construction.

SUMMARY

In order to solve the above problems, the present invention provides a micro tensile strain monitoring sensor and preparation method thereof. The invention can not only monitor the large deformation of the road, but also effectively monitor the deformation in the range of road tensile strain less than 100*10°°, with extremely high monitoring accuracy and sensitivity. In terms of engineering application and service life, it can be effectively applied to the road engineering field where the construction and working environment are often harsh, and its rigidity is matched with that of asphalt concrete pavement structure layer, with long service life and high survival rate.

In terms of cost performance of sensors, it can control the cost within 800 yuan/sensor, greatly reduce the unit price of sensors on the premise of ensuring the monitoring accuracy and engineering application, and has remarkable economic and social benefits.

According to some embodiments, the present disclosure adopts the following technical scheme:

A micro tensile strain monitoring sensor comprises a main structure, a conductive electrode and an encapsulation layer, wherein the main structure comprises a resin polymer matrix, a multi-scale non-metallic carbon conductor, a compound toughening agent, a coupling agent, a curing agent, a curing accelerator and a dispersant; the outer side of the main structure is provided with an encapsulation layer, and at least two ends of the main structure are respectively provided with a conductive electrode extending to the outer side of the encapsulation layer.

Optionally, by mass, 100 parts of resin polymer, 0.75-2.5 parts of carbon nanotubes and carbon black, 3-18 parts of carbon black, 2-15 parts of toughening agent, 3-5 parts of coupling agent, 25-45 parts of curing agent and 2 parts of curing 00817 accelerator are used as multi-scale non-metallic carbon materials.

Optionally, the resin polymer matrix is a mixture of one or more of pure epoxy resin, polyurethane modified epoxy resin, polyamide modified epoxy resin and urea-formaldehyde melamine epoxy resin;

Optionally, epoxy value of the resin polymer matrix is 0.4 to 0.6 eq/100g.

Optionally, the carbon nanotubes are at least one of single-walled carbon nanotubes, double-walled carbon nanotubes and multi-walled carbon nanotubes;

Optionally, the specific surface area of carbon nanotubes should be >280m?/g, and the conductivity should be >160s/cm;

Optionally, the specific surface area of carbon black should be 60m?/g - 140m?/g.

Optionally, the toughening agent is a rubber toughening agent and a thermoplastic elastomer toughening agent.

Optionally, the rubber toughening agent is one or more of polysulfide rubber, carboxyl liquid nitrile rubber, polyether, polysulfone and polyimide;

Optionally, the thermoplastic elastomer toughening agent is one or more of polyurethane and polyamide.

Optionally, the coupling agent is one of 3-(2,3-epoxypropyl) propyl trimethoxysilane (KH-560) or y-aminopropyl triethoxysilane (KH-550).

Optionally, the curing agent is a mixture of one or more of vinyl triamine, aminoethyl piperazine, diaminodiphenyl methane, low molecular polyamide curing agent 650#, low molecular polyamide curing agent 651# and 593;

Optionally, the curing accelerator is a mixture of one or more of 2, 4, 6 tris (dimethylaminomethyl) phenol, 2- ethyl -4- methylimidazole and bisphenol A.

Optionally, the dispersant is one of acetone, N-methylpyrrolidone,

N,N-dimethylformamide and dimethyl sulfoxide DMSO.

A preparation method of the micro tensile strain monitoring sensor comprises: (1) drying and grinding multi-scale non-metallic carbon conductive materials; (2) weighing a certain amount of ground multi-scale non-metallic carbon conductive materials in proportion, adding coupling agent and dispersant,

mechanically stirring, and then ultrasonically dispersing to obtain multi-scale 00817 non-metallic carbon conductive material suspension dispersion; (3) adding a certain amount of polymer matrix and toughening agent into the suspension dispersion, and sequentially applying mechanical stirring and ultrasonic dispersion; (4) after ultrasonic dispersion, cooling the sample, adding curing agent and curing accelerator, and applying mechanical stirring; (5) pouring the sample into a mould, and directly placing a copper conductive electrode at a pre-set position in the pouring spline; (6) placing the obtained casting body for vacuumizing, drying and curing, cooling to room temperature, and taking out the semi-cured sample from the mould, (7) preparing that polymer matrix and toughening agent with the same proportion as that of (3), and the cure agent and curing accelerator with the same proportion as that of (4), applying mechanical stirring, and immediately encapsulating and curing the surface of the semi-cured strain resistance response sensitive smart material prepared in (6) by vacuum encapsulation.

As an application, the obtained micro tensile strain monitoring sensor is buried in the bottom or layer of asphalt pavement structure layer to monitor the response relationship between resistance and tensile strain during pavement operation.

Compared with the prior art, the invention has the advantages that: (1) In terms of monitoring performance, the high-precision micro tensile strain monitoring sensor provided by this disclosure can not only monitor the large deformation of the road, but also effectively monitor the deformation within the range of road tensile strain less than 100*10°, with extremely high monitoring accuracy and sensitivity. (2) In terms of engineering application and service life, the high-precision micro tensile strain monitoring sensor provided by this disclosure can be effectively applied to the road engineering field where the construction and working environment are often harsh, and its stiffness is matched with that of the asphalt concrete pavement structure layer, with long service life and high survival rate.

(3) In terms of the cost performance of the sensor, the cost of the high-precision 00817 micro tensile strain monitoring sensor provided by this disclosure is controlled within 800 yuan, which greatly reduces the unit price of the sensor on the premise of ensuring the monitoring accuracy and engineering application. It has remarkable 5 economic and social benefits.

BRIEF DESCRIPTION OF THE FIGURES

The drawings of the specification which form a part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application, and do not constitute undue restrictions on this application.

FIG. 1 is a schematic diagram of the structure of a micro tensile strain monitoring sensor of the present disclosure;

FIG. 2 is a relationship between the resistance change rate and the strain of the pavement surface layer in the embodiment of the present disclosure;

FIG. 3 is a relationship between the resistance change rate and the micro-strain (100 micro-strain) of the pavement surface in the embodiment of the present disclosure;

Among them, 1, strain resistance response sensitive smart material core element, 2, encapsulation material, 3, copper conductive electrode, 4, lead wire, 5, resistance detection instrument.

DESCRIPTION OF THE INVENTION

A typical embodiment of the present disclosure provides a high-precision micro tensile strain monitoring sensor with strain resistance response sensitive smart material as the core element. As shown in Figure 1, the core element of strain resistance response sensitive smart material is made of resin polymer as matrix, multi-scale non-metallic carbon material as conductor, compounded with toughening agent, coupling agent, curing agent, curing accelerator and dispersant. At the same time, the outer side of the matrix is provided with an encapsulation layer, and two ends of the matrix are respectively provided with a conductive electrode extending to 00817 the outer side of the encapsulation layer (copper conductive electrode is selected in this embodiment).

One or more examples of this embodiment include 100 parts of resin polymer, 0.75-2.5 parts of carbon nanotube, 3-18 parts of carbon black, 2-15 parts of toughening agent, 3-5 parts of coupling agent, 25-45 parts of curing agent, 2-6 parts of curing accelerator and 6-6 parts of dispersing agent.

In one or more examples of this embodiment, the resin polymer matrix 1s a mixture of one or more of pure epoxy resin, polyurethane modified epoxy resin, polyamide modified epoxy resin and urea melamine epoxy resin.

Further, the epoxy value of the resin polymer matrix should be 0.4 to 0.6 eq/100 g..

In one or more examples of this embodiment, the multi-scale non-metallic carbon materials are composed of carbon nanotubes and carbon black.

Furthermore, the carbon nanotubes are at least one of single-walled carbon nanotubes, double-walled carbon nanotubes and multi-walled carbon nanotubes.

Furthermore, the specific surface area of carbon nanotubes should be >280m?/g, and the conductivity should be >160s/cm.

Furthermore, the specific surface area of carbon black should be 60 m°/g-140 mg

In one or more examples of this embodiment, the toughening agent is a rubber toughening agent and a thermoplastic elastomer toughening agent.

Further, the rubber toughening agent is one or more of polysulfide rubber, carboxyl liquid nitrile rubber, polyether, polysulfone and polyimide.

Further, the thermoplastic elastomer toughening agent is one or more of polyurethane and polyamide.

In one or more examples of this embodiment, the coupling agent is one of 3- (2,3-epoxypropoxy) propyl trimethoxysilane (KH-560) or y-aminopropyltriethoxy- silane (KH-550).

In one or more examples of this embodiment, the curing agent is a mixture of 00817 one or more of vinyl triamine (DETA), aminoethyl piperazine (AE), diaminodiphenyl methane (DDM), low molecular polyamide curing agent 650#, low molecular polyamide curing agent 651# and 593 curing agent.

In one or more examples of this embodiment, the curing accelerator is a mixture of one or more of 2,4,6 tris (dimethylaminomethyl) phenol (DMP-30), 2- ethyl -4- methylimidazole and bisphenol A.

In one or more examples of this embodiment, the dispersant is one of acetone, N- methylpyrrolidone (NMP), N,N- dimethylformamide (DMF) and dimethyl sulfoxide

DMSO.

Another embodiment of the present disclosure provides a preparation method of the high-precision micro tensile strain monitoring sensor with strain resistance response sensitive smart material as the core element, and the steps are as follows: (1) drying multi-scale non-metallic carbon conductive materials, and grinding with a grinding bowl to promote the dispersion of conductive material particle aggregates, (2) weighing a certain amount of the multi-scale non-metallic carbon conductive material prepared in (1) according to a certain proportion, adding coupling agent and dispersant, mechanically stirring for 20-30 min at a rotating speed of 800-3000rpm, and then ultrasonically dispersing for 20-40 min to obtain the multi-scale non-metallic carbon conductive material suspension dispersion liquid; (3) adding a certain amount of polymer matrix and toughening agent into the multi-scale non-metallic carbon conductive material suspension dispersion prepared in step (2), mechanically stirring for 30-40min, and rotating at 800-3000rpm; (4) ultrasonically dispersing the sample prepared in step (3) for 60-180min, and the ultrasonic power is 1200W-2500W; (5) after the ultrasonic dispersion, cooling the sample, then adding the curing agent and curing accelerator, and mechanically stirring for 5-10 min at 800-3000rpm;

(6) pouring the sample into a mould, and directly placing a copper conductive 00817 electrode at a specific position in the pouring spline. It is a cuboid with a length of 12-24 cm and a square with a side length of 0.6cm, 0.8cm or 1.0cm; (7) placing the casting body in a vacuum drying oven, and vacuumizing for 0.5-1.5 hours at 10-25°C and 0.05-0.10 MPa, taking out the casting body, placing it in an electric-heating blast drying oven at 80-120°C for curing for 0.5-1h, and taking out the semi-cured sample from the mould after cooling to room temperature; (8) prepare that polymer matrix and toughening agent with the same proportion as that of (3), the cure agent and curing accelerator with the same proportion as that of (5), mechanically stirring for 5-10 min, and rotating at 800-3000rpm, then immediately encapsulating the surface of the semi-cured strain resistance response sensitive smart material prepared in (7) by vacuum encapsulation, pay attention to the copper conductive electrodes on both sides during the encapsulation process to avoid contacting the encapsulation material. After encapsulation, place the sensor at room temperature for curing for 2-4 hours, and then place it in an electric heating drying oven at 120-150°C for post-curing for 2-4h, removing auxiliary materials related to vacuum encapsulation after complete curing and moulding.

The above-mentioned high-precision micro tensile strain monitoring sensor is buried in the bottom or layer of asphalt pavement structure layer to monitor the response relationship between resistance and tensile strain during pavement operation.

In order to enable those skilled in the art to have a clearer understanding of the technical scheme of the present disclosure, the technical scheme of the present disclosure will be explained in detail below with specific examples. Of course, in other embodiments, the parameters of specific materials can be appropriately changed.

Example: (1) weigh 1.25g of multi-walled carbon nanotube with a diameter of 10-20nm, a length of 30-60um, a specific surface area of 380m?*/g and a conductivity of 380s/cm, and weigh 6g of carbon black with a surface area of 80m?/g, then drying a multi-scale non-metallic carbon conductive material formed by mixing them, and grinding with a 00817 grinding bowl to promote the dispersion of conductive material particle aggregates; (2) add coupling agent y-aminopropyl triethoxysilane (KH-550)3.0g and dispersant N,N- dimethylformamide (DMF)40mL into the multi-scale non-metallic carbon conductive material prepared in step (1), mechanically stir at 2000rpm for 20min, and then ultrasonically disperse for 20min to prepare the multi-scale carbon black and carbon nanotube conductive material suspension dispersion; (3) add 80g of pure epoxy resin with epoxy value of 0.48~0.54 eq/ 100g, 20g of polyamide modified epoxy resin with epoxy value of 0.41-0.47 eq/ 100g and 3g of toughening agent polyimide into the above-mentioned multi-scale carbon black and carbon nanotube conductive material suspension dispersion, and mechanically stir at 1500 rpm for 30min; (4) ultrasonically disperse the above samples for 120min, and the ultrasonic power is 2500W; (5) after the ultrasonic dispersion, cool the sample, then add curing agent 650# 30g of low molecular polyamide curing agent and curing accelerator DMP-30 2g, and mechanically stir at 2500 rpm for 10min, (6) pour the sample into a polytetrafluoroethylene mould with a length of 22cm* width of 0.6cm* height of 0.6cm, and place the copper conductive electrode after pouring; (7) place the above-mentioned casting body in a vacuum drying oven, and vacuum for 1h at 25°C and 0.10MPa to remove bubbles, take out the casting body, place in an electric heating drying oven at 80°C for curing for 1 hour, and take out the semi-cured sample from the mould after cooling to room temperature; (8) weigh 40g of pure epoxy resin with epoxy value of 0.48-0.54 eq/ 100g, 40g of polyamide modified epoxy resin with epoxy value of 0.41-0.47 eq/ 100g, curing agent low molecular polyamide curing agent 650# 15g and curing accelerator

DMP-30 1g, mechanically stir for Smin, and rotate at 800rpm; then, the semi-cured strain resistance response sensitive smart material surface is encapsulated by vacuum encapsulation, and the copper conductive electrodes on both sides are prevented from contacting the encapsulation material during the encapsulation process. After the 00817 encapsulation is completed, the sensor is placed at room temperature for curing for 2h, and then placed in an electrothermal blast drying oven at 150°C for post-curing for 4h.

After complete curing and moulding, the auxiliary materials related to vacuum encapsulation are removed.

The above-mentioned high-precision micro tensile strain monitoring sensor is horizontally buried at the bottom of asphalt pavement layers to monitor the response relationship between resistance and tensile strain during pavement operation.

Example performance index:

Tensile strength: 74MPa;

Elastic modulus: 1380mpa;

There is an obvious change relationship with the strain of the asphalt pavement surface, as shown in FIG. 2 and FIG. 3.

The above is only the preferred embodiment of the present application, and it is not intended to limit the present application. For those skilled in the art, the present application can be modified and varied. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of this application shall be included in the scope of protection of this application.

Although the specific embodiments of this disclosure have been described with reference to the accompanying drawings, it is not a limitation on the scope of protection of this disclosure. It should be understood by those skilled in the art that on the basis of the technical scheme of this disclosure, various modifications or variations that can be made by those skilled in the art without creative labour are still within the scope of protection of this disclosure.

Claims

CLAIMS LU503175

1. A micro tensile strain monitoring sensor, characterized by comprising a main structure, a conductive electrode and an encapsulation layer, wherein the main structure comprises a resin polymer matrix, a multi-scale non-metallic carbon conductor, a compound toughening agent, a coupling agent, a curing agent, a curing accelerator and a dispersant; the outer side of the main structure 1s provided with an encapsulation layer, and at least two ends of the main structure are respectively provided with a conductive electrode extending to the outer side of the encapsulation layer.

2. The micro tensile strain monitoring sensor according to claim 1, characterized in that, by mass, 100 parts of resin polymer, 0.75-2.5 parts of carbon nanotubes, 3-18 parts of carbon black, 2-15 parts of toughening agent, 3-5 parts of coupling agent, 25-45 parts of curing agent and 2 parts of curing accelerator are used as multi-scale non-metallic carbon materials.

3. The micro tensile strain monitoring sensor according to claim 1, characterized in that the resin polymer matrix is a mixture of one or more of pure epoxy resin, polyurethane modified epoxy resin, polyamide modified epoxy resin and urea-formaldehyde melamine epoxy resin; or, that epoxy value of the resin polymer matrix is 0.4 to 0.6 eq/100g.

4. The micro tensile strain monitoring sensor according to claim 2, characterized in that the carbon nanotubes are at least one of single-walled carbon nanotubes, double-walled carbon nanotubes and multi-walled carbon nanotubes; or, the specific surface area of carbon nanotubes is >280m%/g, and the conductivity is >160s/cm; or, the specific surface area of carbon black is 60m°/g - 140m*/g.

5. The micro tensile strain monitoring sensor according to claim 1, characterized in 00817 that the toughening agent is a rubber toughening agent and a thermoplastic elastomer toughening agent.

6. The micro tensile strain monitoring sensor according to claim 5, characterized in that the rubber toughening agent is one or more of polysulfide rubber, carboxyl liquid nitrile rubber, polyether, polysulfone and polyimide; or, the thermoplastic elastomer toughening agent is one or more of polyurethane and polyamide.

7. The micro tensile strain monitoring sensor according to claim 1, characterized in that the coupling agent is one of 3-(2,3-epoxypropyl) propyl trimethoxysilane (KH-560) or y-aminopropyl triethoxysilane (KH-550).

8. The micro tensile strain monitoring sensor according to claim 1, characterized in that the curing agent is a mixture of one or more of vinyl triamine, aminoethyl piperazine, diaminodiphenyl methane, low molecular polyamide curing agent 650#, low molecular polyamide curing agent 651# and 593; or, the curing accelerator is a mixture of one or more of 2, 4, 6 tris (dimethylaminomethyl) phenol, 2-ethyl-4-methylimidazole and bisphenol A.

9. The micro tensile strain monitoring sensor according to claim 1, characterized in that the dispersant is one of acetone, N-methylpyrrolidone, N,N-dimethylformamide and dimethyl sulfoxide DMSO.

10. A preparation method of the micro tensile strain monitoring sensor according to claim 1, characterized by comprising: (1) drying and grinding multi-scale non-metallic carbon conductive materials; (2) weighing a certain amount of ground multi-scale non-metallic carbon conductive materials in proportion, adding coupling agent and dispersant,

mechanically stirring, and then ultrasonically dispersing to obtain 00817 multi-scale non-metallic carbon conductive material suspension dispersion;

(3) adding a certain amount of resin polymer matrix and toughening agent into the suspension dispersion, and sequentially mechanically stirring and ultrasonic dispersion;

(4) after ultrasonic dispersion, cooling the sample, adding curing agent and curing accelerator, and mechanically stirring;

(5) pouring the sample into a mould, and directly placing a copper conductive electrode at a pre-set position in the pouring spline;

(6) placing the obtained casting body for vacuumizing, drying and curing, cooling to room temperature, and taking out the semi-cured sample from the mould;

(7) preparing the resin polymer matrix and toughening agent with the same proportion as that of (3), and the cure agent and curing accelerator with the same proportion as that of (4), mechanically stirring, and immediately encapsulating and curing the surface of the semi-cured strain-responsive smart material prepared in (6) by vacuum encapsulation.