CN110684375B

CN110684375B - Pyrolytic carbon black modification method for loading carbon nano tube on surface of pyrolytic carbon black

Info

Publication number: CN110684375B
Application number: CN201911057594.9A
Authority: CN
Inventors: 史新妍; 殷浩; 宫小文; 段咏欣
Original assignee: Qingdao University of Science and Technology
Current assignee: Qingdao University of Science and Technology
Priority date: 2019-11-01
Filing date: 2019-11-01
Publication date: 2020-11-17
Anticipated expiration: 2039-11-01
Also published as: CN110684375A

Abstract

The invention discloses a method for modifying pyrolytic carbon black by loading carbon nanotubes on the surface of the pyrolytic carbon black, and belongs to the technical field of material preparation. The method of the invention utilizes the characteristics of low viscosity and high diffusivity of the supercritical fluid and the density close to liquid, takes the supercritical carbon dioxide as a dispersion medium, and utilizes the sufficient kinetic energy of the supercritical fluid to disperse the carbon nanotubes and enable the carbon nanotubes to be deposited and interpenetrated on the surface of the pyrolytic carbon black during stirring. Compared with untreated pyrolytic carbon black, the pyrolytic carbon black loaded with carbon nanotubes on the surface, which is prepared by the method, can improve the modulus, tensile strength and hardness of vulcanized rubber to a certain extent, increase the energy required by the vulcanized rubber in tensile fracture and improve the tensile property of the vulcanized rubber.

Description

Pyrolytic carbon black modification method for loading carbon nano tube on surface of pyrolytic carbon black

Technical Field

The invention relates to the technical field of preparation of pyrolytic carbon black materials, in particular to a pyrolytic carbon black modification method for loading carbon nanotubes on the surface of pyrolytic carbon black.

Background

With the rapid development of the modern automobile industry, the consumption of rubber products, particularly tires, is increased, and the quantity of waste tires produced in China is two hundred million each year, so that a large quantity of waste tires cause serious pollution to the environment. The raw material of the rubber industry is mainly petroleum, and the waste rubber is a fuel with high calorific value, the calorific value is 31397J/kg generally, and the calorific value of waste tires is 33494J/kg. The existing recycling means meets the requirements of life and production to a certain extent, wherein the pyrolysis of the waste tires provides a route with high added value and environmental friendliness. Pyrolysis (also known as pyrolysis, thermal cracking) refers to a chemical reaction in which organic components in solid waste are thermally degraded by high temperature in an oxygen-deficient or inert gas atmosphere, volatile products are released, and solid coke is formed. The waste tire can be pyrolyzed to recover organic liquid, regenerated carbon black, steel wires and combustible gas, combustible waste gas can be used as energy after being recovered, and the pyrolyzed carbon black (CBp) and pyrolysis oil are main products of pyrolysis of the waste tire.

Various properties of tire pyrolytic carbon black are different from those of ordinary commercial carbon black. The types of carbon black used by rubber at different parts of the tire are different, and various impurities and carbon are deposited on the surface of the pyrolytic carbon black in the pyrolysis process, so the particle size of the pyrolytic carbon black is generally 50-1000 nm, and bimodal or trimodal distribution is presented. Meanwhile, in the pyrolysis process, the surface active points of the pyrolytic carbon black are inactivated at high temperature, ash such as metal salt in rubber is deposited on the surface of the pyrolytic carbon black, and carbon generated in the pyrolysis blocks holes on the surface of the pyrolytic carbon black to reduce the structure degree of the pyrolytic carbon black. The properties of the pyrolytic carbon black limit the recycling of the pyrolytic carbon black, so that the method has important significance for effectively modifying the pyrolytic carbon black to enhance the recycling value of the pyrolytic carbon black.

Supercritical fluids (supercritical fluids) are fluids at temperatures and pressures above their critical state. The state of matter at temperatures and pressures above the critical point is classified as a supercritical fluid. Supercritical fluids have many excellent properties: near zero surface tension, near the viscosity and diffusion coefficient of the gas, and near the density and solvating power of the liquid. The excellent properties of supercritical fluids have led to many applications, such as supercritical extraction, supercritical foaming, supercritical drying, supercritical reaction, and supercritical fluid deposition.

Carbon nanotubes are one-dimensional quantum materials with a special structure (radial dimension is of the order of nanometers, axial dimension is of the order of micrometers, and both ends of the tube are basically sealed). Carbon nanotubes are coaxial circular tubes consisting of several to tens of layers of carbon atoms arranged in a hexagonal pattern. The layers are maintained at a fixed distance of about 0.34nm, with a diameter of typically 2-20 nm. By utilizing the properties of the carbon nano tube, a plurality of composite materials with excellent performance can be manufactured. For example, the plastic reinforced by the carbon nano tube material has the advantages of excellent mechanical property, good conductivity, corrosion resistance and radio wave shielding. The carbon nanotube composite material using the cement as the matrix has the advantages of good impact resistance, static electricity prevention, wear resistance, high stability and difficult influence on the environment. The carbon nano tube reinforced ceramic composite material has high strength and good shock resistance.

At present, the method for loading the carbon nano tubes on the surface of the pyrolytic carbon black is less, the modification effect is poorer, and more carbon nano tubes cannot be loaded on the surface of the pyrolytic carbon black. Therefore, the invention creatively adopts the supercritical fluid deposition method to load the carbon nano tubes on the surface of the pyrolytic carbon black so as to carry out surface modification on the pyrolytic carbon black, thereby effectively enhancing the application performance of the pyrolytic carbon black.

Disclosure of Invention

The invention aims to provide a method for modifying pyrolytic carbon black by loading carbon nanotubes on the surface of the pyrolytic carbon black by a supercritical fluid deposition method, so as to solve the preparation problem of a carbon nanotube/pyrolytic carbon black composite material and apply the prepared composite material to the performance of reinforcing rubber.

In order to achieve the above object, the present invention provides a method for modifying pyrolytic carbon black by loading carbon nanotubes on the surface of pyrolytic carbon black, wherein the method comprises the following steps:

(1) weighing carbon nano tubes and pyrolytic carbon black, and sequentially and respectively pouring the carbon nano tubes and the pyrolytic carbon black into a reaction kettle;

(2) screwing down a kettle cover of the reaction kettle and then placing the kettle cover in a heating cavity of a heating and stirring controller;

(3) after the temperature is raised to the set temperature, CO is filled in₂Setting stirring parameters when the air pressure is set, and starting stirring;

(4) and after stirring, standing for 5min, and releasing pressure and opening the kettle to obtain the carbon nano tube/pyrolytic carbon black composite material.

Preferably, the mass ratio of the carbon nanotubes and the pyrolytic carbon black weighed in the step (1) is 1: 25.

Preferably, the set temperature in the step (3) is 50 ℃.

Preferably, the set air pressure in the step (3) is 8.5 MPa.

Preferably, the stirring parameter set in the step (3) is 540r/min, the stirring is carried out for 15min, then the speed is reduced to 270r/min, the stirring is carried out for 15min, and finally the speed is reduced to 90r/min, and the stirring is carried out for 10 min.

In addition, the invention also provides a carbon nano tube/pyrolytic carbon black composite material, and the composite material is prepared by the modification method.

In addition, the invention also provides an application of the carbon nanotube/pyrolytic carbon black composite material, and the carbon nanotube/pyrolytic carbon black composite material prepared by the modification method is applied to performance reinforcement of rubber.

The invention has the beneficial effects that:

1. the method for modifying the pyrolytic carbon black by loading the carbon nano tubes on the surface of the pyrolytic carbon black is simple in preparation steps, and the prepared material is applied to rubber performance reinforcement to improve the tensile stress strain, the physical and mechanical properties, the average particle size, the storage modulus and the like of rubber.

2. In the method, the carbon nanotubes are dispersed by using low viscosity and high diffusivity in a supercritical state and high kinetic energy under stirring, the carbon nanotubes are loaded in gaps on the surface of the pyrolytic carbon black and are alternately deposited, and finally the surface-modified hybrid particles of the pyrolytic carbon black wrapped by the carbon nanotubes are formed.

Drawings

FIG. 1 is a tensile stress strain curve comparing CBp/CNT/SF with CBp and CBp/CNT.

FIG. 2 is the integrated area of the tensile stress strain curves for CBp/CNT/SF versus CBp, CBp/CNT.

FIG. 3 is a comparison of the average particle size of CBp/CNT/SF with CBp and CBp/CNT.

FIG. 4 is a strain sweep plot of storage modulus for CBp/CNT/SF versus CBp, CBp/CNT.

FIG. 5 is a scanning electron micrograph of the apparent morphologies of CBp/CNT/SF and CBp, CBp/CNT.

Detailed Description

In order to clearly illustrate the technical features of the present solution, the present solution is explained below by way of specific embodiments.

Example 1

Weighing 0.1g CNT (carbon nano tube) and 2.5g CBp (pyrolytic carbon black), respectively pouring CNT and CBp into a reaction kettle in sequence, screwing down the kettle cover of the reaction kettle, and placing the reaction kettle in the reaction kettleHeating the heating cavity of the heating and stirring controller, heating to 50 deg.C, and introducing CO²And (2) starting stirring when the pressure reaches 8.5MPa, setting the stirring speed to be 540r/min, reducing the stirring speed to 270r/min after stirring for 15min, reducing the stirring speed to 90r/min after continuing stirring for 15min, closing the stirring after 10min, standing for 5min, releasing pressure, opening a kettle, and taking materials to obtain CBp/CNT/SF (SF: Supercritical Fluid).

The differences in physical properties of CBp/CNT/SF according to the present invention compared to CBp/CNT prepared by CBp alone and by simple mechanical fabrication are compared by specific experiments.

1. Experimental formulation

A set of natural rubber basic formulas are adopted for comparing the application performance of the carbon black, and the specific formula is shown in Table 1

TABLE 1 Experimental formulation

Control 1 was prepared from pyrolytic carbon black alone, and control 2 was prepared from CBp/CNT (prepared by simple mechanical shaking in a sealed bag at a certain ratio to simulate the mechanical blending process in an internal mixer), wherein the mass ratio of CBp to CNT was 25:1 as in example 1.

2. Test sample preparation

Banburying is carried out by adopting a 60ml Hamp torque rheometer RM-200C: the temperature of an internal mixing chamber is 60 ℃, the roller speed is 60r/min, and 1/2 reinforcing filler, zinc oxide and stearic acid are added after 1 minute and 30 seconds of raw rubber are added. The remaining 1/2 reinforcing filler and cure system were added at 3 minutes and 4 minutes 30 seconds to strip. And (4) discharging the sheet on a double-roller open mill by 1.5 mm. (control 1, control 2, same rubber mixing process of example 1, only the fillers used were different.)

3. Experimental methods

1. Mechanical Property test

The tensile strength, the elongation at break and the tensile stress are tested by an electronic tensile machine according to the GB/T528-2009 standard.

2. Dynamic Light Scattering (DLS) testing

And (3) adopting a laser particle size analyzer to test the particle sizes of the three carbon blacks.

3. Dynamic mechanical property test

Strain scan testing was performed using a rubber processing analyzer RPA 2000. The sample was a 5g disc type sample, strain scanned: the frequency is 1Hz, the temperature is 60 ℃, and the strain range is 0-100%.

5. Scanning electron microscope

The test specimens were 3 solid powders.

CBp without any treatment, CBp/CNT/SF obtained after supercritical fluid treatment and CBp/CNT obtained after simple mechanical shock blending (putting into a sealed bag according to a certain proportion and shaking shock to simulate the mechanical blending process of an internal mixer) are observed on the surface appearance of the particles by using a scanning electron microscope.

4. Results of the experiment

4.1 physical Properties mechanical Properties

As shown in fig. 1 and 2, the tensile stress strain of example 1 was higher than control 1, demonstrating that the rubber reinforced with CBp/CNT/SF of the present invention was higher in tensile stress strain than the rubber reinforced with CBp alone; although example 1 is lower in tensile stress strain than control 2 compared to control 2, it can be seen from fig. 2 that the ability to break is highest for rubber reinforced with CBp/CNT/SF of the invention, and thus, from an energy perspective, the ability to stretch is best for rubber reinforced with CBp/CNT/SF of the invention.

TABLE 2 physical and mechanical Properties of the vulcanizates

As can be seen from Table 2, the rubber reinforced with CBp/CNT/SF of the present invention increased tensile strength, hardness, modulus of the vulcanizate, and substantially unchanged elongation at break compared to the rubber reinforced with CBp alone; compared with CBp/CNT reinforced rubber prepared by simple mechanical oscillation, the methods of tensile strength, hardness and the like are basically the same, but the rubber reinforced by CBp/CNT/SF is superior to CBp/CNT prepared by simple machinery in elongation at break.

4.2 average particle diameter comparison

As can be seen from fig. 2, the average particle sizes of the control group 1 and the group 2 are substantially the same, while the average particle size of the example 1 is significantly larger than the two, which illustrates that the supercritical CO2 deposition method of the present invention can deposit a certain amount of CNTs on the surface CBp. Secondly, the DLS test sample is subjected to an ultrasonic dispersion process, so that the bonding force between the CNTs deposited on the CBp surface and CBp has a certain strength, and the CNTs and CBp are not destroyed and separated by ultrasonic vibration.

4.3 storage modulus comparison

As can be seen from FIG. 3, the decrease in storage modulus during the strain increase was much greater for control 2 and example 1 than for control 1 and was similar, indicating that the CBp/CNT/SF reinforced rubber of the present invention is superior in rigidity to the rubber reinforced with CBp alone, but is substantially the same as the CBp/CNT reinforced rubber prepared by simple machinery.

4.4 particle morphology by scanning Electron microscopy

As can be seen from fig. 4, the surface of the control group 2 has substantially no CNT adhesion, while the surface entanglement of the example 1 deposits a considerable layer of CNTs, demonstrating that the supercritical fluid treatment can disperse CNTs and then interpenetrate the deposition on CBp surface, and successfully surface-modify CBp.

In conclusion, CBp/CNT/SF prepared by the method of the invention has the advantages that CNTs are successfully interpenetrated and deposited on the surface of CBp, the modification of the surface of CBp is successfully realized, and the mechanical property of CBp/CNT/SF with the modified surface of the CNTs is obviously better than that of unmodified CBp.

Claims

1. A method for modifying pyrolytic carbon black by loading carbon nanotubes on the surface of the pyrolytic carbon black is characterized by comprising the following preparation steps:

(3) raising the temperature to 50 ℃, and introducing CO₂Until the air pressure is 8.5MPa, and then the stirring parameter is set to be 5Stirring for 15min at 40r/min, then cooling to 270r/min, stirring for 15min, finally cooling to 90r/min, and stirring for 10 min;

2. The modification method according to claim 1, wherein the mass ratio of the carbon nanotubes and the pyrolytic carbon black weighed in the step (1) is 1: 25.

3. A carbon nanotube/pyrolytic carbon black composite, wherein the composite is prepared by the modification method of claim 1.

4. The application of the carbon nanotube/pyrolytic carbon black composite material is characterized in that the carbon nanotube/pyrolytic carbon black composite material prepared by the modification method of claim 1 is applied to the performance reinforcement of rubber.