Graphene and low-cost preparation method thereof

A graphene, low-cost technology, applied in the field of graphene and its low-cost preparation, can solve the problems of high cost, difficult scale production, difficult transfer, etc., achieve high room temperature electrical conductivity and thermal conductivity, reduce raw material costs, The effect of reducing environmental pressure

Active Publication Date: 2018-07-24

HUBEI INST OF AEROSPACE CHEMOTECH

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AI-Extracted Technical Summary

Problems solved by technology

Micro-mechanical exfoliation method can produce micron-scale graphene, but its controllability is poor, the yield is low, and it is difficult to carry out large-scale production; the epitaxial growth method can obtain large-scale graphene by heating and epitaxial growth on the SiC (0001) crystal surface area of single-layer graphene, but its growth efficiency is low, poor controllability and difficult to transfer; oxidation-reduction method is the mainstream method o...

Abstract

The invention relates to graphene and a low-cost preparation method thereof. The low-cost preparation method comprises the following steps: carrying out ultrasonic cleaning on plastic products; then crushing the plastic product and carrying out ball milling to obtain a plastic product micro-fragment; then carbonizing and carrying out the ball milling to obtain carbonized powder with fine granularity; carrying out secondary calcination on the carbonized powder; washing, purifying and drying to finally obtain the graphene. The graphene provided by the invention takes the plastic product or dailywaste plastic products, especially polyethylene plastic, polystyrene plastic and the like, as raw materials and the graphene is prepared through a specific technological method; the prepared graphenenot only has the advantages of low cost, controllable layer number, large specific surface area and high electric conductivity, and waste plastic is used as the raw material so that the environment protection pressure is greatly reduced; the method is suitable for preparation and production of the low-cost graphene and a result can be applied to researches of conducting materials, environment protection, coating, heat dissipation structures and solid propellants.

Application Domain

Graphene

Technology Topic

PolystyreneMetallurgy +8

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Examples

Experimental program(13)

Example Embodiment

[0045] The low-cost preparation method of graphene of the present invention specifically includes the following steps:

[0046] (1) Cut the plastic product into a solvent and place it in an ultrasonic cleaning machine for a period of time to remove the printing ink and attached contaminants on the surface of the plastic bag. The plastic products can be discarded plastic products, such as plastic bags, plastic bottles, plastic films, or plastic skins, and can be polyethylene plastic products, polystyrene plastic products, or polypropylene plastic products.

[0047] In this step, the ultrasonic frequency is 100-1000W, and the ultrasonic time is 5-60min. The selected cleaning solvent is absolute ethanol, acetone, tetrahydrofuran, ethyl acetate, ether or dimethylformamide.

[0048] (2) Use a precision knife to break the cleaned plastic products into small pieces, and then clean them again with a solvent; the selected solvent is the same as step (1).

[0049] (3) The small pieces of plastic products are placed in a ball milling tank for a period of high-speed ball milling according to a certain ball-to-material ratio to obtain curled plastic product micro-fragments. The mass ratio of the ball-to-materials of the ball mill is 10:1 to 100:1. The ball milling speed is 2000-10000rpm, and the ball milling time is 30-200min. The obtained plastic product micro-fragments have a sheet diameter of several micrometers to hundreds of micrometers.

[0050] (4) Placing micro-fragments of plastic products in a vacuum furnace for high-temperature carbonization, and ball milling the carbonized powder block for a period of time to obtain carbonized powder. Among them, the high temperature carbonization temperature is 800~1500℃, the carbonization time is 5~80min; the vacuum degree in the vacuum furnace is less than 10 -3 MPa; The milling speed is 1000~8000rpm, and the milling time is 10~150min.

[0051] The particle size of the carbonized powder obtained in this step is 10 nm to 200 nm.

[0052] (5) The carbonized powder after ball milling is placed in a vacuum furnace for secondary calcination under reducing gas and protective gas. The calcination temperature is 1000-1500°C, and the calcination time is 10-80min.

[0053] In this step, the reducing gas is hydrogen or carbon monoxide, and the mass flow rate of the reducing gas is 10-200 sccm. The shielding gas is nitrogen, helium, argon or neon, and the mass flow rate of the shielding gas is 100-800 sccm.

[0054] (6) The powder after the second calcination is washed, purified, and dried multiple times to obtain graphene. The washing times are 2-6 times, and the washing solvent is deionized water, absolute ethanol, acetone or ethyl acetate.

[0055] The purification process in this step is one or a combination of centrifugal separation, electrodialysis, suction filtration, dialysis or molecular membrane filtration.

[0056] The drying temperature is 20~80℃, and the drying time is 2~12h.

[0057] The present invention also provides graphene prepared by the above method.

Example Embodiment

[0058] Example 1:

[0059] Step 1: Cut the polyethylene plastic bag into tetrahydrofuran and place it in an ultrasonic cleaning machine at 300W for 40 minutes to remove the printing ink and attached contaminants on the surface of the plastic bag;

[0060] Step 2: Use a precision knife to break the cleaned polyethylene plastic bag into small pieces, and then clean it again with tetrahydrofuran, the method is the same as step 1;

[0061] Step 3: Put the small pieces of polyethylene plastic bag in a ball milling tank at a ball-to-material ratio of 50:1 at 6000 rpm for 70 minutes to obtain curled polyethylene plastic bag micro-fragments; the obtained micro-fragments have a diameter of 40-70 microns;

[0062] Step 4: Place the micro-fragments of the polyethylene plastic bag in a vacuum furnace for carbonization at 1200°C for 20 minutes, and mill the carbonized powder mass at 4000 rpm for 60 minutes to obtain carbonized powder; the vacuum degree in the vacuum furnace is <10 -3 MPa; The particle size of the obtained carbonized powder is 200 nm.

[0063] Step 5: Place the ball-milled carbonized powder in a vacuum furnace for secondary calcination at 1300°C under CO (mass flow rate of 50 sccm) and He (mass flow rate of 300 sccm) for 40 minutes;

[0064] Step 6: The powder after the second calcination is washed twice with acetone and then subjected to suction filtration and centrifugal separation, and then dried at 35° C. for 6 hours to obtain graphene.

[0065] Graphene properties: purity: 99.4%, specific surface area: 536m 2 /g, powder conductivity: 1850S/m, thermal conductivity: 1125W/(m·K).

Example Embodiment

[0066] Example 2:

[0067] Step 1: Cut the polyethylene plastic bag into acetone and place it in an ultrasonic cleaning machine at 400W for 30 minutes to remove the printing ink and attached contaminants on the surface of the plastic bag;

[0068] Step 2: Use a precision knife to break the cleaned polyethylene plastic bag into small pieces, and then clean it again with acetone; the method is the same as step 1;

[0069] Step 3: Put the small pieces of polyethylene plastic bag in a ball milling tank at a ball-to-material ratio of 70:1 at 9000 rpm for 50 minutes to obtain curled polyethylene plastic bag micro-fragments; the obtained micro-fragments have a diameter of 10-30 microns;

[0070] Step 4: Place the micro-fragments of the polyethylene plastic bag in a vacuum furnace for carbonization at 1300°C for 20 minutes, and mill the carbonized powder mass at 5000 rpm for 80 minutes to obtain carbonized powder; the vacuum degree in the vacuum furnace is less than 10 -3 MPa; The particle size of the obtained carbonized powder is 25nm;

[0071] Step 5: Place the carbonized powder after ball milling in a vacuum furnace in H 2 (Mass flow 120sccm) and Ar (mass flow 500sccm) at 1400℃ for the second calcination for 45min;

[0072] Step 6: The powder after the second calcination is washed with acetone for 4 times and then subjected to molecular membrane filtration, and then dried at 30° C. for 5 hours to obtain graphene.

[0073] Graphene properties: purity: 99.6%, specific surface area: 765m 2 /g, powder conductivity: 2460S/m, thermal conductivity: 1314W/(m·K).

PUM

Property	Measurement	Unit
Particle size	10.0 ~ 200.0	nm
Film diameter	40.0 ~ 70.0	µm
Specific surface area	536.0	m²/g

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

Reduce raw material costs
low cost

Graphene and low-cost preparation method thereof

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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