TWI790784B - Graphene polyester composite material and manufacturing method thereof - Google Patents

Abstract

A graphene polyester composite material, which includes a polymer molecular chain and multiple graphenes formed by polymerizing multiple dibasic acid molecules and multiple dibasic alcohol molecules, it is characterized in that each graphene is grafted on the Each diol molecule. The polymer molecular chains may be polyethylene terephthalate molecular chains. The steps of the method for making the graphene polyester composite material include: oxidizing a graphite with a solution of supercritical carbon dioxide and an oxidizing agent to form graphite oxide; exfoliating the graphite oxide into multiple graphene oxides; reducing each graphene oxide into complex graphene oxides Graphene oxide; Grafting each reduced graphene oxide on ethylene glycol to obtain a modified ethylene glycol; and polymerizing the modified ethylene glycol and terephthalic acid to obtain a graphene polyester composite material. The present invention provides a modified material that directly combines graphene and polymer monomers, so that graphene does not fall off and disappear with use, and different modification effects can be achieved by different types of reduced graphene oxide.

Description

Graphene polyester composite material and manufacturing method thereof

The invention relates to a graphene polymer modified material and a manufacturing method thereof, in particular to a graphene polyester composite material in which reduced graphene oxide is grafted to diol and then polymerized, and a manufacturing method thereof.

Graphene is a hexagonal honeycomb lattice material composed of carbon atoms, with only one carbon atom thickness, which makes graphene have many unique and excellent properties, such as: 1. Very strong conductivity: the resistivity of graphene is about 10 ^-6 ohm‧cm, lower than copper and silver and other metals. 2. High thermal conductivity: The thermal conductivity of graphene is 5300w/m‧k, which is higher than that of diamond. 3. Super large specific surface area: The specific surface area of single-layer graphene can reach 2600m ² /g, while the specific surface area of ordinary activated carbon is 1500m ² /g. 4. Ultra-high strength: the Young's modulus of graphene is 1100GPa, and that of carbon nanotubes is 1000GPa. Therefore, graphene has triggered a research boom in various material fields, whether it is added to any material or coated on the outer layer of existing materials, the research has sprung up and published.

Graphene can be used as a variety of functional fillers to develop various conductive, thermally conductive, heat-resistant, gas barrier and structurally reinforced composite materials. Graphene's high light transmission can also be made into PVA and PET films. The common mass production method of graphene is the Hummers' method, which uses sulfuric acid, potassium permanganate and sodium nitrate to oxidize graphite first and then peels it into graphene oxide (Graphene Oxide, GO), and then reduces it to Reduction of graphene oxide into reduced graphene oxide (Reduced Graphene Oxide, rGO), and the degree of reduction of reduced graphene oxide can be controlled by the reduction conditions, usually the higher the degree of reduction, the conductivity of reduced graphene oxide the higher. Functional groups on the surface of graphene oxide, such as carboxyl groups, carbonyl groups, epoxy groups, etc., can be hydrophilic (graphene is hydrophobic), which can help graphene oxide disperse in aqueous solutions and prevent graphene from agglomerating. Back to graphite, the secondary functional groups form controllable chemical defects, use these defects as the nucleation center of metal growth, control the purpose of metal growth, and improve the catalytic function; or reduce oxidation Graphene is used to trap and kill viruses. However, the Hummers method will produce harmful sulfuric acid vapor, nitrogen dioxide and dinitrogen tetroxide and other harmful gases.

Because the specific surface area and van der Waals force of the nano-scale graphene additive are quite large in the state of a single layer, if the graphene is directly mixed into the polymerized polyester material and then the fiber drawing operation is performed, the graphene is easy to be drawn. When the temperature rises during operation, it will be reunited or superimposed again. Graphene is a material with a high aspect ratio. After reuniting or superimposing, the volume will increase, which will easily cause nozzle blockage during drawing, resulting in excessive pressure rise and causing equipment shutdown. Graphene cannot be directly mixed into textile fibers, and another method of dispersing graphene is required.

Therefore, the known methods of combining graphene and polyester materials are mostly to attach graphene to the outer layer of polyester materials by coating. Then apply the method on the outside of a fiber; or disclose in my country's patent certificate number I707906, prepare a graphene resin solution, and then apply or print the solution on a fabric to form a graphene constant temperature fabric to utilize graphene Excellent anisotropic thermal conductivity, far-infrared absorption and release, high electrical conductivity and other characteristics. In this way of coating, the graphene only stays on the surface layer of the polyester material. After a period of use, the graphene will eventually fall off from the polyester material, losing its effect and affecting the service life; and single-layer graphene In the process of mixing into slurry or solution and in the process of coating, there are still opportunities to agglomerate or overlap each other, which reduces the improvement effect brought by graphene.

In addition, there is a modification method of applying graphene to graft (or claim to be grafted) graphene to other polymers, for example, in the patent CN 107709454 of the People's Republic of China, graphene is grafted to poly(acrylonitrile-CO-cis-butylene) Diamide imide) as a thin film for water filtration, and describe that graphene oxide can be more uniformly dispersed than graphene, and graphene oxide can also change the hydrophobicity of graphene; or the patent CN 106543534 of the People's Republic of China will Graphene is grafted to double-amino-terminated polyethylene glycol (PEG) or polyvinyl alcohol (PVA), and then added to another polymer to allow the graphene to be evenly distributed.

In view of this, the present inventor is concentrating on research, design and assembly, expecting to provide a graphene polyester composite material and its manufacturing method, which is the motivation of the present invention.

The main purpose of the present invention is to provide a graphene polyester composite material and its manufacturing method, which can make graphene evenly distributed in polyester without re-aggregation, and can change the degree of polymerization by controlling the degree of reduction and oxidation of graphene. Properties of ester composites.

The graphene polyester composite material of the present invention comprises a polymer molecular chain formed by polymerizing a plurality of dibasic acid molecules and a plurality of dibasic alcohol molecules and a plurality of graphenes, and is characterized in that each graphene is polymerized before Grafted on each diol molecule. Each dibasic acid molecule can be a terephthalic acid (TA) molecule, each diol molecule can be an ethylene glycol (EG) molecule, and the polymer molecular chain can be a polyethylene terephthalic acid molecule. Polyethylene terephthalate (PET) molecular chain. The graphene grafted on the polymer molecular chain will no longer be aggregated into a group.

Each graphene can be a single-layer reduced graphene oxide, rather than a multi-layer agglomerated or stacked state. The length of each graphene can be between 5-30 microns. The weight percentage of each graphene and polymer molecular chain can be between 0.1wt%~10wt%.

Since the common method of mass production of graphene is to use the Hummers method to manufacture graphite oxide and then exfoliate a single layer of graphene oxide, the application form of graphene also includes graphene oxide (Graphene Oxide, GO) and the reduction of GO. Reduced Graphene Oxide (Reduced Graphene Oxide, rGO), the oxide layer on the surface of GO can prevent graphene from stacking and aggregating each other, and help graphene to disperse; and the surface of graphene oxide has functional bonds brought by the oxide layer (such as hydroxyl and carboxyl) The surface properties of graphene oxide can be changed, and GO can be planned to be reduced according to the properties of the final product to make rGO, for example, rGO can be made to absorb UV, the surface of rGO can be hydrophilic or hydrophobic, or It can capture pathogens; the conductivity of GO decreases due to oxidation, and rGO can control the degree of reduction to achieve the required conductivity; so the application surface of rGO has very high flexibility. If various functional rGOs are co-polymerized with polyester, graphene-polyester composites with various special properties can be created.

The manufacturing method of the graphene polyester composite material of the present invention comprises: a graphite is oxidized into a graphite oxide with a solution of a supercritical carbon dioxide and an oxidizing agent; the graphite oxide is stripped into a plurality of graphene oxides; each graphene oxide is reduced into a plurality reducing graphene oxide; grafting each reduced graphene oxide on ethylene glycol to obtain a modified ethylene glycol; and polymerizing the modified ethylene glycol and terephthalic acid to obtain a graphene polyester composite material. Each reduced graphene oxide may be a single-layer reduced graphene oxide, rather than a multi-layer agglomerated or stacked state.

Because supercritical carbon dioxide has a high ability to penetrate and move between graphite layers, supercritical carbon dioxide can transport the oxidant dissolved in it to between graphite layers, so that an oxide layer is formed between graphite layers, and then use ultrasonic vibration and other methods to dissipate Graphene oxide is exfoliated so that graphene oxide can be dispersed in aqueous solution. The use of supercritical carbon dioxide will not consume sulfuric acid and produce harmful gases like the Hummers method.

The reduction of graphene oxide can be carried out by hydrothermal reduction, which is relatively simple, safe and economical. For example, reduction at 190°C for 24 hours. The reduction can also be carried out with drugs such as hydrazine hydrate, hydroquinone, sodium borohydride (NaBH ₄ ) and ascorbic acid.

There is another method of grafting reduced graphene oxide, which can first carry out glycolysis of PET into ethylene terephthalate monomer, then graft reduced graphene oxide on the part of ethylene glycol, and then polymerize .

In order to further understand the characteristics, characteristics and technical content of the present invention, please refer to the following detailed description of the present invention.

Please refer to the first figure to the second figure, which reveals the legend of the embodiment of the present invention. The method for making the graphene polyester composite material of the present invention is illustrated by the above figure. The solution of critical carbon dioxide and oxidant is oxidized into graphite monoxide; step S2, exfoliating graphite oxide into complex graphene oxide; step S3, reducing each graphene oxide into complex reduced graphene oxide; step S4, reducing each reduced graphene oxide Grafting to ethylene glycol to obtain a modified ethylene glycol; and step S5, polymerizing the modified ethylene glycol and terephthalic acid to obtain a graphene polyester composite material. In this embodiment, each reduced graphene oxide may be a single-layer reduced graphene oxide, rather than a multi-layer agglomerated or stacked state.

The detailed polymerization process of step S5 can be: adding a catalyst to the modified ethylene glycol; adding terephthalic acid to the modified ethylene glycol; performing polymerization under a nitrogen environment; vacuuming to remove excess ethylene glycol; Cool and dry the finished product.

Because supercritical carbon dioxide has a high ability to penetrate and move between graphite layers, supercritical carbon dioxide can transport the oxidant dissolved in it to between graphite layers, oxidize between graphite layers to form graphite oxide, and then use ultrasonic vibration and other methods To exfoliate graphite oxide into graphene oxide. The use of supercritical carbon dioxide will not consume sulfuric acid and produce harmful gases like the Hummers method. The reduction of graphene oxide can be carried out by hydrothermal reduction, which is relatively simple, safe and economical. In this example, it was reduced at 190°C for 24 hours, which is a low-level reduction of graphene oxide, so as to retain more functional bonds to help reduce graphene oxide dispersion and strengthen PET. More functional bonds also allow this embodiment to capture The positively charged coronavirus on the surface is not killed, so that this embodiment can be made into melt-blown cloth and used as one of the layers of mask filter cloth.

The oxide layer on the surface of graphene oxide can prevent graphene from stacking and aggregating each other, and help graphene to disperse; and the surface of graphene oxide has functional bonds (such as hydroxyl and bonding groups) brought by the oxide layer, which can change the surface characteristics of graphene oxide. And according to the nature requirements of the final product, GO can be reduced in a planned way to make rGO, for example, rGO can be made to absorb UV, the surface of rGO can be hydrophilic or hydrophobic, or it can capture pathogens; GO is oxidized so As the conductivity decreases, rGO can control the degree of reduction to achieve the required conductivity; therefore, the application surface of rGO has very high flexibility. If various functional rGOs are co-polymerized with polyester, graphene-polyester composites with various special properties can be created. Graphene oxide can also be reduced with drugs such as hydrazine hydrate, hydroquinone, sodium borohydride (NaBH ₄ ) and ascorbic acid.

The graphene polyester composite material of the present invention comprises a polymer molecular chain formed by polymerizing a plurality of dibasic acid molecules and a plurality of dibasic alcohol molecules and a plurality of graphenes, and is characterized in that each graphene is polymerized before Grafted on each diol molecule. In this embodiment, each dibasic acid molecule is a terephthalic acid molecule respectively, each dibasic alcohol molecule is an ethylene glycol molecule respectively, and the polymer molecular chain is a polyethylene terephthalate molecular chain; each graphene In this embodiment, each is a reduced graphene oxide, and each graphene can be a single-layer reduced graphene oxide, rather than a multi-layer agglomerated or stacked state.

The second picture is a photo of the fiber produced by the embodiment of the present invention. The fiber in the picture is extruded by a capillary rheometer Rheoscope 1000 (CEAST, Italy) at a pressure of 0.7-1.5 bars and a temperature of 280°C. The first image (B) is an enlarged view of the single fiber in the first image (A), and the length of the scale bar in the lower right corner of the first image (B) is 100 microns. In the first figure (B), it can be seen that the reduced graphene oxide is dispersed in the fiber, and the length of the reduced graphene oxide is about 30 microns or less.

Tables (a) and (b) compare the physical properties of the fiber made of the graphene polyester composite material of the present invention and the unmodified conventional PET fiber. In Table (a), the glass transition temperature of the graphene polyester composite fiber of the present invention is slightly lower, the crystallization temperature and heat of fusion are higher, and the melting temperature and crystallinity are approximately the same. In table (b), it can be seen that the tensile strength (130) of the fiber made by the present invention can be twice that of the conventional PET (60), and the present invention can also be extended longer before breaking. The Young's modulus is also about 80% higher than that of conventional PET materials, which shows that the physical properties of this creation are better than that of conventional PET materials.

There is another method of grafting reduced graphene oxide in PET, which can first carry out glycolysis of PET into ethylene terephthalate monomer, and then graft reduced graphene oxide on the part of ethylene glycol, and then Polymerize again.

However, the above are only preferred embodiments of the present invention, and should not be used to limit the scope of the present invention. All changes and modifications that are obvious to those skilled in the industry should be regarded as not departing from The essence of the present invention.

Table (a) Comparison table of physical properties between this creation and conventional PET fibers (1) Material Glass transition temperature °C Crystallization temperature °C (Note 1) Melting temperature °C (Note 2) Heat of fusion J/g Crystallinity % (Note 3) this invention 72.8 195.6 244.4 46.6 33.3 Known PET 80.5 164.4 249.2 40.1 32.1 Note 1: Measured at the first cooling by DSC method at a rate of 10K/min. Note 2: Measured in the second heating with the DSC method at a rate of 10K/min. Note 3: It is assumed that the heat of fusion of PET with 100% crystallinity is a converted value of 140J/g.

Table (b) Comparison table of physical properties between this creation and conventional PET fibers (2) Material Tensile strengthMpa Elongation at break% Young's modulus Gpa Intrinsic viscosity dl/g this invention 130±20 720±180 1.9±0.5 0.6 Known PET 60±10 630±110 1.1±0.1 0.78

S1: step S2: step S3: step S4: step S5: step

The first figure is a flow chart of the production method of the graphene polyester composite material of the present invention.

The second figure is a schematic diagram of the fiber of the graphene polyester composite material of the present invention.

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S1: step

S2: step

S3: step

S4: step

S5: step

Claims (6)

A graphene polyester composite material, which includes a polymer molecular chain formed by polymerizing a plurality of terephthalic acid molecules and a plurality of ethylene glycol molecules and a plurality of reduced graphene oxides, characterized in that each of the reduced graphene oxides is Grafted onto each of the ethylene glycol molecules prior to polymerization. The graphene polyester composite material as described in claim 1, wherein the length of each reduced graphene oxide is between 5 and 30 microns. The graphene polyester composite material as described in Claim 1, wherein the weight percentage of each of the reduced graphene oxide and the polymer molecular chain is between 0.1wt% and 10wt%. A method for making a graphene polyester composite material, the steps comprising: oxidizing a graphite into a graphite oxide with a solution of a supercritical carbon dioxide and an oxidizing agent; exfoliating the graphite oxide into a plurality of graphene oxides; ene is reduced to multiple reduced graphene oxides; each of the reduced graphene oxides is grafted onto ethylene glycol to obtain a modified ethylene glycol; and the modified ethylene glycol is polymerized with terephthalic acid to obtain a graphene Polyester composite. The manufacture method of the graphene polyester composite material as described in claim 4, wherein the length of each of the reduced graphene oxide is between 5 and 30 microns. The manufacturing method of the graphene polyester composite material as described in Claim 4, wherein the weight percentage of each of the reduced graphene oxide and the graphene polyester composite material is between 0.1wt% and 10wt%.

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