CN106671386B

CN106671386B - Shaft-diameter bidirectional conductivity controllable conductive polymer pipe and preparation method thereof

Info

Publication number: CN106671386B
Application number: CN201611226753.XA
Authority: CN
Inventors: 白时兵; 聂敏; 李怡俊; 王琪
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2016-12-27
Filing date: 2016-12-27
Publication date: 2020-10-16
Anticipated expiration: 2036-12-27
Also published as: CN106671386A

Abstract

The invention belongs to the technical field of conductive polymer materials, and particularly relates to a conductive polymer pipe with controllable axial and radial bidirectional conductivity and a preparation method thereof. The technical problem to be solved by the invention is to provide a preparation method of a shaft-diameter bidirectional conductivity controllable conductive polymer pipe, which comprises the following steps: and (3) uniformly mixing the polymer and the conductive filler, then putting the mixture into a polymer pipe rotary extrusion device for melt rotary extrusion, and cooling and sizing the extruded pipe blank. The method can induce the conductive filler to change from single-dimensional orientation to multi-dimensional orientation in the pipe wall, and promote the formation of a conductive network; meanwhile, a hybrid conductive filler system with a larger connection degree is formed by utilizing different morphological responses of the multidimensional conductive filler in a rotating flow field, so that the permeation threshold value of the conductive polymer pipe is greatly reduced, the consumption of expensive conductive filler is reduced, and the conductive polymer pipe with high conductivity, excellent processability and mechanical property is prepared.

Description

Shaft-diameter bidirectional conductivity controllable conductive polymer pipe and preparation method thereof

Technical Field

The invention belongs to the technical field of conductive polymer materials, and particularly relates to a conductive polymer pipe with controllable axial and radial bidirectional conductivity and a preparation method thereof.

Background

The conductive polymer is a composite material which realizes the conductive performance of the polymer by adding one or more conductive fillers, and has very wide application prospect in the fields of static resistance, electromagnetic shielding, sensors, conductors and the like. Conductive polymer tubes are a special type of conductive material with high added value and special purpose, especially microtubes with a diameter of less than 5mm and the special shape thereof have important use in the fields of flexible sensors and medical health, and are gradually receiving attention from the academia and the industry (US 4278835A). However, it is difficult to maintain the conductive properties of the polymer material during the processing of the polymer tube. The key point of preparing the polymer conductive material is that a conductive path can be formed in a polymer matrix, but in the traditional melt extrusion or injection molding processing process, polymer melt is subjected to extremely strong shearing or stretching action, so that the conductive filler is subjected to single-dimensional high orientation in the polymer matrix.

U.S. Pat. No. 1.Al-Saleh M H and Sundaraj U.S. Electromagentic conductivity of CNT/polymer composites [ J ]. Carbon,2009.47(7):1738-1746.2.Arjmand M, application T, Okonewski M, and SundarajU.S. Pat. No. 10 of Electron conductivity of electronic components [ J ]. Carbon,2012.50(14):5126-5134.3. Arjomand M, Magmo M, Gemini A, Paragnene A, Paragne/polymer composites [ J ]. Pat. No. 5. sub.S.No. 5. sub.3. electronic components of electronic components [ J ]. Carbon,2012.50(14): 5134.3. Arjones M, Magnetorhod J ]. Pat. No. 3. sub.3. mu.3. electronic components of electronic components [ J ]. 5. sub.S.11. sub.S.S.3. sub.3. Pat. 2. sub.3. Carbone orientation of electronic components [ J.: Polyinstructions [ 12. sub.7. C.3. C.S.S.S.S.S.S.S.3. sub.S.3. electronic components of electronic components [ 12. sub.12. C.3. C.12. C.S.12. sub.7. C.S.S.12. sub.S.S.12. sub.3. C.S.3. sub.3. C.3. No. C.S.3. sub.E.3. sub.3. No. C.3. sub.E., the extremely thick polymer insulating layer exists between the highly oriented conductive fibers, so that the conductive fibers are difficult to contact with each other to form a conductive path, and the percolation threshold of the material is greatly improved. In the production process of the conductive polymer pipe, the polymer melt is strongly stretched, and conductive fillers such as carbon fibers, carbon nanotubes and the like in the polymer melt are highly oriented, so that the production difficulty of the conductive polymer pipe is higher than that of a traditional injection molding sample. Therefore, conventional production processes often require the addition of large amounts of conductive fillers or more complex production processes such as filament extrusion and the like. However, these processes have significant drawbacks: the addition of a large amount of conductive filler can greatly reduce the mechanical properties of the polymer pipe, and the polymer pipe fails in the using process; the special production process, for example, embedding long conductive fibers such as carbon fibers and metal wires in a polymer for direct extrusion, has extremely high technical requirements on an extrusion machine, is not beneficial to large-scale traditional industrial production, and greatly limits the popularization of products.

With the development of national economy and strong market competition, higher requirements are put on the production and performance of conductive polymer pipes, if high conductivity, excellent processability and mechanical properties are expected, but the existing processing method of the polymer pipes is difficult to realize.

Disclosure of Invention

The invention aims to provide a shaft-diameter bidirectional conductivity controllable conductive polymer pipe and a preparation method thereof aiming at the defects of insufficient processing technology and large addition amount of conductive filler in the prior art.

The invention aims to solve the first technical problem of providing a preparation method of a shaft-diameter bidirectional conductivity controllable conductive polymer pipe. The method comprises the following steps: and (3) uniformly mixing the polymer and the conductive filler, then putting the mixture into a polymer pipe rotary extrusion device for melt rotary extrusion, and cooling and sizing the extruded pipe blank.

Preferably, in the above method for preparing a tube of conductive polymer with controllable axial and radial bidirectional conductivity, the device for rotational extrusion of the polymer tube is ZL 200810045785.9; the rotation is any one of a mode in which the core rod rotates independently with respect to the die, a mode in which the die rotates independently with respect to the core rod, a mode in which the core rod rotates simultaneously in the same direction as the die, and a mode in which the core rod rotates simultaneously in the opposite direction as the die.

Further, in the above method for preparing the tube of conductive polymer with controllable axial and radial bidirectional conductivity, the rotation is performed by rotating the core rod and the neck mold in opposite directions.

Furthermore, in the above method for preparing the conductive polymer tube with controllable axial and radial bidirectional conductivity, when the core rod and the neck ring rotate in the same direction or in the opposite direction, the rotation speeds of the core rod and the neck ring are the same or different.

Preferably, in the preparation method of the conductive polymer tube with controllable axial-diameter bidirectional conductivity, the polymer and the conductive filler are added in a ratio of 50-99.99 parts by weight of polymer and 0.01-50 parts by weight of conductive filler.

Further, in the preparation method of the conductive polymer pipe with controllable axial and radial bidirectional conductivity, the polymer and the conductive filler are added in a ratio of 70-99.9 parts by weight of polymer to 0.1-30 parts by weight of conductive filler.

Preferably, in the above method for preparing the tube of conductive polymer with controllable axial-diameter bidirectional conductivity, the polymer is at least one of polyethylene, polypropylene, polybutylene, polyvinyl chloride, nylon, polyurethane, polyolefin elastomer or polyvinyl acetate.

Further, in the above method for producing a tube of a conductive polymer having a controlled axial-radial bidirectional conductivity, the polyolefin elastomer is a high polymer of ethylene and butene, or a high polymer of ethylene and octene.

Preferably, in the above method for preparing a tube of a conductive polymer with controllable axial-radial bidirectional conductivity, the conductive filler is at least one of carbon fiber, carbon black, graphene, carbon nanotube, iron powder or stainless steel fiber.

Further, in the above method for preparing the conductive polymer tube with controllable axial-radial bidirectional conductivity, the conductive filler is a mixture of carbon fiber and graphene or a mixture of carbon fiber and carbon black.

Preferably, in the method for preparing the conductive polymer pipe with controllable axial and radial bidirectional conductivity, the rotating speed is 1-60 rpm/min.

Further, in the preparation method of the shaft-diameter bidirectional conductivity controllable conductive polymer pipe, the rotating speed is 10-40 rpm/min.

Furthermore, in the preparation method of the shaft-diameter bidirectional conductivity controllable conductive polymer pipe, the rotating speed is 15-30 rpm/min.

Preferably, in the above method for preparing the conductive polymer pipe with controllable axial-diameter bidirectional conductivity, other additives or fillers are added according to the need.

Further, in the above method for preparing the conductive polymer tube with controllable axial-diameter bidirectional conductivity, the other auxiliary agent is at least one of an antioxidant, a plasticizer, a heat stabilizer, a light stabilizer, a flame retardant, an antistatic agent, a mildew preventive, a coloring agent, a whitening agent, a filler, a coupling agent and a lubricant.

Further, in the above method for preparing the conductive polymer tube with controllable axial and radial bidirectional conductivity, the filler is at least one of glass fiber, glass microsphere, talcum powder, montmorillonite, mica, wollastonite and calcium carbonate.

The second technical problem to be solved by the invention is to provide the shaft diameter bidirectional conductivity controllable conductive polymer pipe prepared by the preparation method of the shaft diameter bidirectional conductivity controllable conductive polymer pipe.

Preferably, the axial-diameter bidirectional conductivity controllable conductive polymer pipe has a conductivity of 1.0 × 10 in the axial direction^-41.0S/cm, a conductivity in the radial direction of 1.0 × 10^-11～1.0×10^-1S/cm。

The third technical problem to be solved by the invention is to provide the application of the axial-diameter bidirectional conductivity controllable conductive polymer tube as a strain sensor.

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

1) the method applies a rotating force field in the process of preparing the conductive polymer pipe, can form multidimensional orientation in the conductive filler in the pipe wall of the polymer pipe by simply changing the rotating mode and the rotating speed, controls the orientation degree, and forms a conductive network structure with controllable connection density, thereby realizing the conductive polymer pipe with freely controllable conductivity.

2) The rotary extrusion technology adopted by the method has the characteristics of generating laminar flow on the surface of the melt and generating vortex flow inside the melt in the melt extrusion processing process, so that the conductive fillers on the surface of the conductive tube are regularly arranged, the conductive capacity of the wall surface of the conductive tube can be regulated, and the high-performance special conductive tube with a conductive core layer and an insulating skin layer is prepared; furthermore, along with the increase of the rotating speed, the multi-dimensional oriented conducting filler cap-exchanging range in the tube wall is gradually enlarged, and the special conducting tube with axial-diameter bidirectional conduction can also be prepared. The two different conductive tubes can be applied to various fields, are simple to regulate and control and have competitive advantages.

3) The conductivity of the conductive polymer tube prepared by the method of the invention has response to tube deformation such as bending, stretching, twisting and the like, namely the conductivity of the polymer tube changes along with the deformation, thereby being applied to the fields of deformation response sensors and the like.

4) The method adopts the rotary extrusion hybrid conductive filler system technology, the conductive filler seepage threshold is low, the addition amount is small, and the production efficiency is high, so that the prepared pipe not only has the competitive advantage of high quality, but also has price competitiveness due to low cost.

5) The method adopts melt extrusion processing, so the processing speed is high, the yield is high, and the method meets the requirements of industrial large-scale production; the method provided by the invention has the advantages of simple and mature process, easy control and convenient popularization and application.

Drawings

FIG. 1 is a schematic view of a conductive portion of a conductive tube obtained by the method of the present invention;

FIG. 2 is a schematic diagram of the conductive filler forming a conductive path during processing according to the method of the present invention;

on the surfaces of the inner wall and the outer wall of the conductive polymer tube, the conductive fillers are arranged in parallel to ensure that the polymer tube has insulativity in the radial direction, and in the middle layer of the tube, the conductive fillers are oriented in multiple dimensions and are contacted with each other to form a conductive path, so that the tube has extremely high conductivity in the axial direction; with the increase of the rotating speed, the middle multidimensional orientation layer gradually expands towards the surface of the inner wall and the outer wall, and finally the conductive polymer pipe also has good conductive performance in the radial direction.

FIG. 3 is a comparison graph of a scanning electron microscope after etching inner and outer walls of a conductive pipe extruded by a core rod and a neck mold rotating in opposite directions at the same time in 30r/min by using 15 parts by weight of carbon fiber and 85 parts by weight of low density polyethylene in the conventional extrusion and the method of the present invention;

wherein, the drawings a and b are respectively the inner wall and the outer wall of a conventional extruded tube, the drawings c and d are respectively the inner wall and the outer wall of the conductive tube of the invention, and the arrow direction in the drawings is the extrusion direction of the tube; as can be seen from the figure, the carbon fibers are arranged in a deviated axial direction and the deviation directions of the inner wall and the outer wall are opposite through rotary extrusion, so that the carbon fibers form a three-dimensional conductive path in the polymer tube, and the rapid improvement of the conductivity is realized.

Detailed Description

In the traditional method for preparing the polymer conductive material by melt extrusion or injection molding, the polymer melt is subjected to extremely strong shearing or stretching action, so that the conductive filler is highly oriented in a single dimension in a polymer matrix, and the conductive capacity of the polymer is reduced. And the defects of raw material cost waste, complex operation, long time consumption and the like exist respectively when a large amount of conductive fillers are added or more complex production processes are adopted.

Aiming at the problems in the prior art for preparing the conductive tube, the inventor of the invention finds that a polymer tube rotary extrusion device (ZL200810045785.9) is adopted, the core rod and the neck ring mold of the polymer tube rotary extrusion device are independently adjustable, and the rotating speed and the direction are independently adjustable, so that four different rotating modes, namely, the core rod rotates independently relative to the neck ring mold, the neck ring mold rotates independently relative to the core rod, the core rod rotates simultaneously in the same direction with the neck ring mold or the core rod rotates simultaneously in the opposite direction with the neck ring mold, are superposed with axial extrusion/traction movement, the flow mode of polymer melt is regulated and controlled, different speed distribution and stress distribution along the wall thickness direction of the tube are formed, the stress and speed gradient distribution of the mutually crossed covers in the tube wall are generated, and the conductive filler is induced to form an arrangement mode of the mutually crossed. Meanwhile, the conductive fillers are promoted to contact with each other by utilizing the different morphological responses of the multidimensional conductive fillers (one-dimensional fillers: carbon fibers, two-dimensional fillers: graphene and three-dimensional fillers: carbon black) in a rotating flow field, namely the characteristics that the one-dimensional fillers are easy to deviate and the two three-dimensional fillers are difficult to deviate, so that a hybrid conductive filler system with a larger connection degree is formed, the permeation threshold of the conductive polymer pipe is greatly reduced, and the consumption of the expensive conductive fillers is reduced, thereby preparing the conductive polymer pipe with high conductivity, excellent processability and excellent mechanical property.

Therefore, the invention provides a method for preparing a shaft-diameter bidirectional conductivity controllable conductive polymer pipe, which comprises the following steps: uniformly mixing 50-99.99 parts by weight of polymer and 0.01-50 parts by weight of conductive filler, then putting the mixture into a polymer pipe rotary extrusion device to perform melt rotary extrusion at the rotating speed of 1-60 rpm/min, and cooling and sizing the extruded pipe blank under the traction of a traction machine; the rotation is any one of a mode in which the core rod rotates independently with respect to the die, a mode in which the die rotates independently with respect to the core rod, a mode in which the core rod rotates simultaneously in the same direction as the die, and a mode in which the core rod rotates simultaneously in the opposite direction as the die. The polymer and the conductive filler can also be melt extruded and cut by a conventional method and then put into a polymer tube rotary extrusion device.

Preferably, the rotation is a simultaneous counter-rotation of the core rod and the die.

Preferably, when the core rod and the neck ring mold rotate in the same direction or rotate in opposite directions at the same time, the rotation speeds of the core rod and the neck ring mold are the same or different.

In order to take the conductive effect and energy saving into consideration, the rotation speed is preferably 10-40 rpm/min. The rotating speed is further 15-30 rpm/min.

In order to take the conductive effect and energy saving into consideration, the polymer and the conductive filler are preferably added in a proportion of 70-99.9 parts by weight of the polymer and 0.1-30 parts by weight of the conductive filler.

Preferably, the polymer is at least one of polyethylene, polypropylene, polybutylene, polyvinyl chloride, nylon, polyurethane, polyolefin elastomer, or polyvinyl acetate.

Preferably, the conductive filler is at least one of carbon fiber, carbon black, graphene, carbon nanotube, iron powder or stainless steel fiber. Further, in order to ensure the conductive effect, the conductive filler should be a mixture of a one-dimensional filler and a two-dimensional filler, or a mixture of a one-dimensional filler and a three-dimensional filler. Further, the conductive filler is a mixture of carbon fiber and graphene or a mixture of carbon fiber and carbon black.

Further, in the actual industrial production, according to the requirements of application fields on the performance of the polymer pipe, other well-known processing aids such as antioxidants, plasticizers, heat stabilizers, light stabilizers, flame retardants, antistatic agents, mildew inhibitors, coloring agents, whitening agents, fillers, coupling agents, lubricants and the like can be added, and other fillers which can be used for further enhancing the performance of the pipe can be added, such as glass fibers, glass microspheres, talcum powder, montmorillonite, mica, wollastonite, calcium carbonate and the like.

The inventor finds that the conductive part of the conductive tube can be controlled by adjusting the rotating speed of the device and the concentration of the conductive filler in the method of the invention. At low rotation speed, the conductive fibers on the inner wall surface of the tube are arranged in parallel in one dimension and do not conduct electricity, and the inner part forms a conductive network of a three-dimensional cross cover due to the speed difference formed by rotary extrusion, so that the conductive network conducts electricity in the axial direction and does not conduct electricity in the radial direction. Along with the increase of the rotating speed, the range of the three-dimensional cap-overlapping network is gradually enlarged, and finally, a conductive network is also formed on the surface of the inner wall and the outer wall of the pipe, namely, the two-way conduction is realized in the axial and radial directions. Along with the increase of the content of the conductive filler, the critical rotating speed required for realizing axial and radial bidirectional conduction is gradually reduced.

The inventors have also found that factors affecting the conductivity in the method of the present invention are the rotation speed, the rotation mode, the amount of filler added, the kind of filler, and the like. When the threshold value is not reached, the threshold value can be controlled by adjusting the rotating speed, the rotating mode, the adding amount of the filler and the type of the filler; once the threshold value is reached, the influence of the adding amount of the filler on the conductivity is small, the conductivity gradually rises and finally tends to be unchanged by increasing the adding amount of the conductive filler, and the conductivity can be controlled by adjusting the rotating speed and the rotating mode.

By the method, various influencing factors can be reasonably controlled according to the requirements of the application field, so that the conductive tube with controllable conductive parts and controllable conductivity is prepared.

The invention also provides the axial-diameter bidirectional conductivity controllable conductive polymer pipe prepared by the method, and further, the conductivity in the axial direction is 1.0 × 10^-41.0S/cm, a conductivity in the radial direction of 1.0 × 10^-11～1.0×10^- ¹S/cm。

The inventor also finds that the shaft-diameter bidirectional conductivity controllable conductive polymer pipe is subjected to bending, stretching, twisting and other deformation, and has response to the deformation, namely the conductivity of the pipe changes along with the deformation, so that the conductive pipe can be applied to the fields of deformation response sensors and the like.

Therefore, the invention also provides the application of the axial-diameter bidirectional conductivity controllable conductive polymer pipe as a strain sensor.

The present invention will be specifically described below by way of examples. It should be noted that the following examples are only intended to illustrate the present invention and should not be construed as limiting the scope of the present invention, and that those skilled in the art can make modifications and variations of the present invention without departing from the spirit and scope of the present invention.

It is worth mentioning that: 1) the parts of the materials in the following examples and comparative examples are parts by weight. 2) The pipes prepared in the following examples and comparative examples were tested for conductivity according to GB1410-78, with conductivity greater than 10^-6S/cm can be considered a conductor.

Example 1

Firstly, 99.99 parts by weight of polyethylene LDPE (No. 2420H) and 0.01 part by weight of carbon nano tube are melted and extruded and granulated in a double-screw extruder, then the obtained granules are placed in a polymer tube rotary extrusion device, a core rod is adopted to independently rotate, the melting and rotary extrusion are carried out at the rotating speed of 10rpm/min, and the extruded tube blank is cooled and sized under the traction of a traction machine to obtain the polymer tube with the diameter phi of 3.

The axial conductivity of the pipe obtained in this example was 1.92 × 10^-3S/cm, radial conductivity 1.5 × 10^-11S/cm。

Example 2

Firstly, 99.9 parts by weight of polyethylene LDPE (No. 2420H) and 0.1 part by weight of graphene are melted and extruded and granulated in a double-screw extruder, then the obtained granules are placed in a polymer tube rotary extrusion device, a mouth mold independently rotates, the granules are melted and rotationally extruded at the rotating speed of 20rpm/min, and the extruded tube blank is cooled and sized under the traction of a traction machine to obtain a polymer tube with the diameter phi of 3.

The axial conductivity of the pipe obtained in this example was 3.92 × 10^-2S/cm, radial conductivity 4.2 × 10^-11S/cm。

Example 3

The method comprises the steps of firstly, melting, extruding and pelletizing 90 parts by weight of polyethylene LDPE (No. 2420H) and 10 parts by weight of carbon fiber twin-screw extruder, then placing obtained pellets in a polymer tube rotary extrusion device, adopting a core rod and neck ring mold reverse rotation mode, melting, rotating and extruding at the rotating speed of 60rpm/min, and cooling and sizing the extruded tube blank under the traction of a traction machine to obtain the polymer tube with the diameter phi of 3.

The axial conductivity of the pipe obtained in this example was 4.1 × 10^-1S/cm, radial conductivity 6.41 × 10^-3S/cm。

Example 4

Firstly, 50 parts by weight of polyethylene LDPE (No. 2420H) and 50 parts by weight of carbon black are melted, extruded and granulated in a double-screw extruder, then the obtained granules are placed in a polymer tube rotary extrusion device, the core rod and a neck ring mold rotate in the same direction, the mixture is melted, rotated and extruded at the rotating speed of 10rpm/min, and the extruded tube blank is cooled and sized under the traction of a traction machine to obtain the polymer tube with the diameter phi of 3.

The axial conductivity of the pipe obtained in this example was 3.92 × 10^-3S/cm, radial conductivity 7 × 10^-11S/cm。

Example 5

The method comprises the steps of firstly carrying out melt extrusion and grain cutting on 60 parts by weight of polybutene and 40 parts by weight of stainless steel fiber in a double-screw extruder, then placing obtained granules in a polymer pipe rotary extrusion device, carrying out melt rotary extrusion at the rotating speed of 1rpm/min in a mode of reverse rotation of a core rod and a neck ring, and carrying out cooling and sizing on an extruded pipe blank under the traction of a traction machine to obtain the polymer pipe with the diameter of phi 3.

The axial conductivity of the pipe obtained in this example was 1.12 × 10^-4S/cm, radial conductivity 6.86 × 10^-11S/cm。

Example 6

Melting and extruding 90 parts by weight of polypropylene and 10 parts by weight of iron powder in a double-screw extruder, granulating, then placing the obtained granules in a polymer pipe rotary extrusion device, melting and rotating and extruding at the rotating speed of 5rpm/min in a mode that a core rod and a neck ring rotate in the same direction, and cooling and sizing the extruded pipe blank under the traction of a tractor to obtain the polymer pipe with the diameter phi 3.

The axial conductivity of the pipe obtained in this example was 2.92 × 10^-3S/cm, radial conductivity 9.11 × 10^-11S/cm。

Example 7

Firstly, melting, extruding and pelletizing 60 parts by weight of polyethylene LDPE (No. 2420H) and 40 parts by weight of stainless steel fiber in a double-screw extruder, then placing the obtained pellets in a polymer tube rotary extrusion device, adopting a mode of single rotation of a core rod, melting, rotating and extruding at the rotating speed of 60rpm/min, and cooling and sizing the extruded tube blank under the traction of a traction machine to obtain the polymer tube with the diameter phi of 3.

The axial conductivity of the pipe obtained in this example was 4.82 × 10^-1S/cm, radial conductivity 1 × 10^-1S/cm。

Example 8

Melting, extruding and granulating 85 parts by weight of polypropylene and 10 parts by weight of carbon fiber 5 parts by weight of graphene in a double-screw extruder, then placing the obtained granules in a polymer pipe rotary extrusion device, adopting a mode of single rotation of a neck ring die, melting, rotating and extruding at the rotating speed of 50rpm/min, and cooling and sizing the extruded pipe blank under the traction of a tractor to obtain the polymer pipe with the diameter of phi 3.

The axial conductivity of the pipe obtained in this example was 9.24 × 10^-1S/cm, radial conductivity 8.11 × 10^-2S/cm。

Example 9

The method comprises the steps of firstly carrying out melt extrusion and grain cutting on 85 parts by weight of polybutene, 10 parts by weight of carbon fiber and 5 parts by weight of carbon black in a double screw extruder, then placing obtained grains in a polymer pipe rotary extrusion device, carrying out melt rotary extrusion at the rotating speed of 30rpm/min in a mode that a core rod and a neck ring rotate in the same direction, and carrying out cooling and sizing on an extruded pipe blank under the traction of a traction machine to obtain the polymer pipe with the diameter phi of 3.

The axial conductivity of the pipe obtained in this example was 1.34 × 10^-1S/cm, radial conductivity 7.51 × 10^-11S/cm。

Example 10

Firstly, melting, extruding and granulating 75 parts by weight of polyurethane, 20 parts by weight of stainless steel fibers and 5 parts by weight of carbon nano tube in a double-screw extruder, then placing the obtained granules in a polymer tube rotary extrusion device, adopting a mode of reverse rotation of a core rod and a neck ring die, melting, rotating and extruding at the rotating speed of 20rpm/min, and cooling and sizing the extruded tube blank under the traction of a traction machine to obtain the polymer tube with the diameter phi 3.

The axial conductivity of the pipe obtained in this example was 7.83 × 10^-2S/cm, radial conductivity 7.21 × 10^-11S/cm。

Example 11

Firstly, 50 parts by weight of polyvinyl acetate, 20 parts by weight of polyurethane and 30 parts by weight of carbon fiber are melted and extruded and granulated in a double-screw extruder, then the obtained granules are placed in a polymer pipe rotary extrusion device, the core rod and a neck ring rotate in the same direction, the melt and rotary extrusion is carried out at the rotating speed of 5rpm/min, and the extruded pipe blank is cooled and sized under the traction of a traction machine to obtain the polymer pipe with the diameter phi of 3.

The axial conductivity of the pipe obtained in this example was 5.12 × 10^-4S/cm, radial conductivity 3.21 × 10^-2S/cm。

Example 12

The method comprises the steps of firstly carrying out melt extrusion and grain cutting on 85 parts by weight of polybutene and 15 parts by weight of carbon fiber twin-screw extruder, then placing obtained granules in a polymer pipe rotary extrusion device, carrying out melt rotary extrusion at the rotating speed of 10rpm/min in a mode of reverse rotation of a core rod and a neck ring, and carrying out cooling and sizing on an extruded pipe blank under the traction of a traction machine to obtain a polymer pipe with the diameter of phi 3.

The axial conductivity of the pipe obtained in this example was 1.12 × 10^-4S/cm, radial conductivity 1.941 × 10^-11S/cm。

Example 13

The method comprises the steps of firstly carrying out melt extrusion and grain cutting on 90 parts by weight of polyurethane and 10 parts by weight of graphene in a double-screw extruder, then placing obtained granules in a polymer pipe rotary extrusion device, carrying out melt rotary extrusion at the rotating speed of 40rpm/min by adopting a mode of single rotation of a mandrel, and cooling an extruded pipe blank under the traction of a tractor to obtain a polymer pipe with the diameter phi 3.

The axial conductivity of the pipe obtained in the example is 1.24S/cm, and the radial conductivity is 1.18 × 10^-1S/cm。

Example 14

The method comprises the steps of firstly carrying out melt extrusion and grain cutting on 90 parts by weight of polyurethane and 5 parts by weight of graphene in a carbon fiber double-screw extruder, then placing obtained grains in a polymer pipe rotary extrusion device, carrying out melt rotary extrusion at the rotating speed of 15rpm/min in a mode of single rotation of a mandrel, and cooling and sizing an extruded pipe blank under the traction of a traction machine to obtain the polymer pipe with the diameter of phi 3.

The axial conductivity of the pipe obtained in this example was 3.74 × 10^-1S/cm, radial conductivity 5.73 × 10^-4S/cm。

Comparative example 1

The method comprises the steps of firstly carrying out melt extrusion and grain cutting on 90 parts by weight of polyurethane and 10 parts by weight of graphene in a double-screw extruder, then placing obtained granules in a polymer pipe conventional extrusion device, and carrying out cooling and sizing on an extruded pipe blank under the traction of a traction machine to obtain a polymer pipe with a diameter phi of 3.

The axial conductivity of the resulting tubing was 2.39 × 10^-10S/cm, radial conductivity 2.21 × 10^-11S/cm。

Comparative example 2

The method comprises the steps of firstly carrying out melt extrusion and grain cutting on 70 parts by weight of LDPE and 30 parts by weight of carbon fiber in a double-screw extruder, then placing obtained granules in a polymer pipe conventional extrusion device to extrude a pipe blank, and carrying out cooling and sizing under the traction of a tractor to obtain the polymer pipe with the diameter of phi 3.

The axial conductivity of the obtained tube was 5.09 × 10^-9S/cm, radial conductivity 1.24 × 10^-11S/cm。

Comparative example 3

Firstly, 50 parts by weight of polyvinyl acetate and 50 parts by weight of carbon black are melted and extruded and granulated in a double-screw extruder, then the obtained granules are placed in a polymer pipe conventional extruding device, and the extruded pipe blank is cooled and sized under the traction of a traction machine to obtain a polymer pipe with the diameter phi of 3.

The axial conductivity of the obtained tube was 9.09 × 10^-9S/cm, radial conductivity 5.1 × 10^-11S/cm。

Comparative example 4

Firstly, melting and extruding 60 parts by weight of polyurethane and 40 parts by weight of iron powder in a double-screw extruder, granulating, then placing the obtained granules in a polymer pipe conventional extruding device, and cooling and sizing the extruded pipe blank under the traction of a tractor to obtain a polymer pipe with the diameter of phi 3.

The axial conductivity of the resulting tubing was 3.93 × 10^-10S/cm, radial conductivity 3.81 × 10^-11S/cm。

Comparative example 5

The method comprises the steps of firstly carrying out melt extrusion and grain cutting on 90 parts by weight of polybutene and 10 parts by weight of carbon nanotube in a double-screw extruder, then placing obtained granules in a polymer pipe conventional extruding device, and carrying out cooling and sizing on an extruded pipe blank under the traction of a traction machine to obtain a polymer pipe with the diameter of phi 3.

The axial conductivity of the resulting tubing was 8.21 × 10^-9S/cm, radial conductivity 1.76 × 10^-11S/cm。

Comparative example 6

Melting and extruding 80 parts by weight of polypropylene and 20 parts by weight of stainless steel fiber in a double-screw extruder, pelletizing, then placing the obtained pellets in a polymer pipe conventional extruding device, and cooling and sizing the extruded pipe blank under the traction of a tractor to obtain the polymer pipe with the diameter phi of 3.

The axial conductivity of the resulting tubing was 4.49 × 10^-11S/cm, radial conductivity 4.12 × 10^-11S/cm。

Comparative example 7

Firstly, melting, extruding and granulating 80 parts by weight of polyurethane and 10 parts by weight of graphene in a 10-weight-fraction carbon nanotube double-screw extruder, then placing the obtained granules in a polymer tube conventional extruding device, and cooling and sizing the extruded tube blank under the traction of a tractor to obtain a polymer tube with the diameter phi of 3.

The axial conductivity of the resulting tubing was 8.81 × 10^-9S/cm, radial conductivity 5.12 × 10^-11S/cm。

Comparative example 8

Firstly, 70 parts by weight of polyurethane, 20 parts by weight of polyvinyl acetate and 10 parts by weight of graphene are melted and extruded and granulated in a double-screw extruder, then the obtained granules are placed in a polymer pipe conventional extruding device, and the extruded pipe blank is cooled and sized under the traction of a traction machine to obtain a polymer pipe with the diameter phi of 3.

The axial conductivity of the resulting tubing was 6.11 × 10^-9S/cm, radial conductivity 1.51 × 10^-11S/cm。

In conclusion, the conductivity of the conductive polymer tube prepared by the method can be higher by several orders of magnitude than that of the conductive polymer tube prepared by the traditional method in the axial and radial methods, and the conductive capability and the conductive part can be adjusted by reasonably controlling the rotating speed and the using amount of the conductive filler according to different requirements of different fields. The invention provides a better choice for conducting polymer pipes in different fields.

Claims

1. The preparation method of the shaft diameter bidirectional conductivity controllable conductive polymer pipe is characterized by comprising the following steps: the method comprises the following steps: uniformly mixing a polymer and a conductive filler, then putting the mixture into a polymer pipe rotary extrusion device for melt rotary extrusion, and cooling and sizing the extruded pipe blank; the rotation is any one of the rotation modes of the core rod rotating independently relative to the neck ring mold, the neck ring mold rotating independently relative to the core rod, the core rod and the neck ring mold rotating in the same direction or the core rod and the neck ring mold rotating in opposite directions; the conductive filler is at least one of carbon fiber, carbon black, carbon nano tube, iron powder or stainless steel fiber; the conductive filler is a mixture of a one-dimensional filler and a two-dimensional filler, or a mixture of a one-dimensional filler and a three-dimensional filler; at low rotation speed, the conducting fibers on the surface of the inner wall of the tube are arranged in parallel in one dimension and do not conduct electricity, a conducting network of a three-dimensional cross cover is formed inside the tube, the conducting network conducts electricity in the axial direction and the radial direction, the range of the conducting network is gradually expanded to the surface of the inner wall of the tube along with the increase of the rotation speed, and the conducting network conducts electricity in the axial direction and the radial direction.

2. The method for producing an axial-diameter bidirectional conductivity controllable conductive polymer pipe according to claim 1, characterized in that: the rotation mode is that the core rod and the neck mold rotate reversely at the same time.

3. The method for producing an axial-diameter bidirectional conductivity controllable conductive polymer pipe according to claim 1, characterized in that: the polymer and the conductive filler are added in a ratio of 50-99.99 parts by weight of polymer to 0.01-50 parts by weight of conductive filler.

4. The method for producing a tube of axial-radial bidirectional conductivity controllable conductive polymer according to claim 3, characterized in that: the polymer and the conductive filler are added in a ratio of 70-99.9 parts by weight of polymer to 0.1-30 parts by weight of conductive filler.

5. The method for producing an axial-diameter bidirectional conductivity controllable conductive polymer pipe according to claim 1, characterized in that: the polymer is at least one of polyethylene, polypropylene, polybutylene, polyvinyl chloride, nylon, polyurethane, polyolefin elastomer or polyvinyl acetate.

6. The method for producing an axial-diameter bidirectional conductivity controllable conductive polymer pipe according to claim 1, characterized in that: the conductive filler is a mixture of carbon fibers and carbon black.

7. The method for producing an axial-diameter bidirectional conductivity controllable conductive polymer pipe according to claim 1, characterized in that: the rotating speed is 1-60 rpm/min.

8. The method of manufacturing a tube of axial-radial bidirectional conductivity controllable conductive polymer according to claim 7, characterized in that: the rotating speed is 10-40 rpm/min.

9. The method of manufacturing a tube of axial-radial bidirectional conductivity controllable conductive polymer according to claim 8, characterized in that: the rotating speed is 15-30 rpm/min.

10. The method for preparing a tube of conductive polymer with controllable axial and radial bidirectional conductivity according to any one of claims 1 to 9, wherein: other auxiliary agents or fillers are added according to the needs.

11. The method of producing an axial-diameter bidirectional conductivity controllable conductive polymer pipe according to claim 10, characterized in that: the other auxiliary agent is at least one of an antioxidant, a plasticizer, a heat stabilizer, a light stabilizer, a flame retardant, an antistatic agent, a mildew inhibitor, a coloring agent, a whitening agent, a filling agent, a coupling agent and a lubricant; the filler is at least one of glass fiber, glass beads, talcum powder, montmorillonite, mica, wollastonite and calcium carbonate.

12. Controllable conducting polymer pipe of two-way conductivity of shaft diameter, its characterized in that: the conductive polymer pipe is prepared by the preparation method of the axial-diameter bidirectional conductivity controllable conductive polymer pipe as claimed in any one of claims 1 to 11.

13. The axial-radial bidirectional conductivity controllable conductive polymer pipe of claim 12, wherein the conductivity in the axial direction is 1.0 × 10^-41.0S/cm, a conductivity in the radial direction of 1.0 × 10^-11～1.0×10^-1S/cm。

14. Use of the axial-diameter bidirectional conductivity controllable conductive polymer tube according to claim 12 or 13 as a strain sensor.