Flame-retardant functionalized carbon nanotube modified polyethylene material and preparation method thereof

Abstract

The invention relates to the technical field of new materials, and discloses a flame-retardant functionalized carbon nanotube modified polyethylene material, which is characterized in that organic functional groups and starch macromolecules are introduced to the surfaces of carbon nanotubes, so that the intermolecular distance of the carbon nanotubes is increased, the agglomeration phenomenon of the carbon nanotubes is inhibited, and the flame-retardant functionalized carbon nanotube modified polyethylene material is prepared. According to the present invention, the carbon nano-tubes are introduced into the polyethylene, such that the carbon nano-tubes can be easily dispersed, the carbon nano-tubes can provide the good mechanical property enhancing effect on the polyethylene, the phosphorus element is introduced on the surfaces of the carbon nano-tubes, the starch having the excellent char forming property is introduced, and the flame-retardant phosphoric acid, the flame-retardant polyphosphoric acid and the like can be formed during combustion so as to promote the char forming of the starch and the polyethylene; according to the present invention, the carbon layer with the barrier property is rapidly formed, and the barrier carbon layer can isolate oxygen and heat so as to prevent the further combustion of the polyethylene material, such that the flame retardation self-extinguishing effect is provided so as to obtain the polyethylene material with characteristics of good flame retardation and good mechanical property.

Description

Technical Field

[0001] The invention relates to the technical field of new materials, in particular to a flame-retardant functionalized carbon nanotube-modified polyethylene material and a preparation method thereof. Background Art

[0002] With the continuous development of the field of materials, the application of organic polymer materials in life is becoming more and more extensive. Articles made of organic polymer materials can be seen everywhere. Among the various types of organic polymer materials, polyethylene is the organic polymer material with the simplest structure. It is made of ethylene polymerization and is odorless, non-toxic, has excellent chemical stability and corrosion resistance. Therefore, it is also widely used in all aspects of life. However, it also has disadvantages such as general mechanical properties, low strength, and lack of flame retardant properties. Therefore, it also needs to be modified to a certain extent so that it can have a wider range of applications.

[0003] In Chinese patent CN109054147B "A graphene-reinforced polyethylene pipe and its preparation method", a polyethylene pipe with graphene as a reinforcing and toughening filler and magnesium hydroxide as a flame retardant is disclosed. However, when graphene and nanomaterials such as carbon nanotubes are directly added to polyethylene, there is a phenomenon of agglomeration, so the modification effect is relatively poor. By organically modifying the surface of carbon nanotubes, the agglomeration of carbon nanotubes themselves can be suppressed. At the same time, the introduction of flame retardant groups and starch with good carbon-forming properties can make the polyethylene material have good flame retardant properties and mechanical properties. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a flame retardant functionalized carbon nanotube modified polyethylene material and a preparation method thereof, which solves the problems of carbon nanotube agglomeration and the lack of flame retardancy and poor mechanical properties of polyethylene materials.

[0005] To achieve the above object, the present invention provides the following technical solution: A method for preparing a flame retardant functionalized carbon nanotube modified polyethylene material comprises the following steps: (1) Dispersing carbon nanotubes in deionized water, ultrasonically treating for 10-20 min, then adding 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1-hydroxybenzotriazole, ultrasonically treating for 30-90 min, then adding 1,3-propylenediamine, ultrasonically treating for 4-8 h, after the reaction is completed, washing with deionized water and acetone, and vacuum drying to obtain amino-modified carbon nanotubes; (2) Adding amino-modified carbon nanotubes, phosphorous acid, and 2 mol / L formaldehyde aqueous solution into deionized water, stirring and refluxing at 60-90° C. for 8-16 h, and after the reaction is completed, centrifuging, washing with deionized water and anhydrous ethanol, and vacuum drying to obtain phosphate-modified carbon nanotubes; (3) adding phosphate-modified carbon nanotubes and catalyst urea to deionized water, then adding starch, ultrasonically treating for 15-30 min, heating to 50-80 °C for reaction for 2-6 h, and after the reaction is completed, centrifugation, deionized water washing, and vacuum drying to obtain flame-retardant functionalized carbon nanotubes; (4) Add low-density polyethylene, flame-retardant functionalized carbon nanotubes, stearic acid and antioxidant 1076 into a double-roll mixer, mix at 200-240° C. for 15-45 min, and then use an injection molding machine to injection mold to obtain a flame-retardant functionalized carbon nanotube modified polyethylene material.

[0006] Preferably, in step (1), the mass fraction of deionized water is 1000-5000 parts, the mass fraction of carbon nanotubes is 10 parts, the mass fraction of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 18-50 parts, the mass fraction of 1-hydroxybenzotriazole is 15-45 parts, and the mass fraction of 1,3-propylenediamine is 60-140 parts.

[0007] Preferably, in step (2), the mass fractions of deionized water are 3000-12000 parts, the mass fractions of amino-modified carbon nanotubes are 100 parts, the mass fractions of phosphorous acid are 20-50 parts, and the mass fractions of formaldehyde are 3-10 parts.

[0008] Preferably, in step (3), the mass fractions of deionized water are 4000-8000 parts, the mass fractions of phosphate-modified carbon nanotubes are 10 parts, the mass fractions of urea are 2-5 parts, and the mass fractions of starch are 10-35 parts.

[0009] Preferably, in step (4), the mass fraction of low-density polyethylene is 100 parts, the mass fraction of flame-retardant functionalized carbon nanotubes is 0.6-2 parts, the mass fraction of stearic acid is 1-2 parts, and the mass fraction of antioxidant 1076 is 0.5-1.5 parts.

[0010] Compared with the prior art, the present invention has the following experimental principles and beneficial technical effects: The flame-retardant functionalized carbon nanotube modified polyethylene material comprises the following steps: firstly modifying carbon nanotubes with 1,3-propylenediamine, then reacting the amino groups on the carbon nanotubes with formaldehyde and phosphorous acid to obtain phosphate modified carbon nanotubes, then reacting the -OH groups on the phosphate groups with the hydroxypropyl groups of starch under the catalysis of urea to graft starch with good carbonization properties onto the surface of the carbon nanotubes, thereby obtaining flame-retardant functionalized carbon nanotubes, and then mixing and injection molding the carbon nanotubes with polyethylene, antioxidants, lubricants and other additives to obtain flame-retardant functionalized carbon nanotube modified polyethylene. Since organic functional groups and starch macromolecules are introduced on the surface of the carbon nanotubes, the distance between carbon nanotube molecules is increased, thereby inhibiting the agglomeration of the carbon nanotubes themselves, thus facilitating the dispersion of the carbon nanotubes and enabling the carbon nanotubes to have a better mechanical property enhancement effect on polyethylene. When subjected to external force, the carbon nanotubes can restrict the movement of polyethylene molecular chains. Meanwhile, due to the excellent mechanical properties of the carbon nanotubes themselves, yield strain can occur when subjected to external force, absorbing a large amount of energy, thereby playing an enhancement role.

[0011] The flame retardant functionalized carbon nanotube modified polyethylene material introduces phosphorus elements and starch with excellent charring properties on the surface of carbon nanotubes, which can form flame retardant phosphoric acid, polyphosphoric acid and the like during combustion, thereby promoting charring of starch and polyethylene and quickly forming a char layer with barrier properties. The barrier char layer can isolate oxygen and heat, thereby preventing further combustion of the polyethylene material and achieving a flame retardant self-extinguishing effect. At the same time, the carbon nanotubes also have a good effect of promoting charring. Under the synergistic effect of the carbon nanotubes, phosphorus elements and starch, the polyethylene has excellent flame retardant properties, thereby obtaining a polyethylene material with good flame retardant and mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Reaction diagram for preparing phosphate-modified carbon nanotubes; Figure 2 Reaction diagram for preparing flame-retardant functionalized carbon nanotubes. DETAILED DESCRIPTION

[0013] A method for preparing a flame retardant functionalized carbon nanotube modified polyethylene material, characterized by comprising the following steps: (1) Disperse 10 mg of carbon nanotubes in 10 ml of deionized water, and ultrasonically treat for 10-20 min. Then, add 18-50 mg of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 15-45 mg of 1-hydroxybenzotriazole, and ultrasonically treat for 30-90 min. Then, add 60-140 mg of 1,3-propylenediamine, and ultrasonically treat for 4-8 h. After the reaction is completed, wash with deionized water and acetone, and vacuum dry to obtain amino-modified carbon nanotubes. (2) Add 1.5 g of amino-modified carbon nanotubes, 0.3-0.75 g of phosphorous acid, and 0.45-1.4 g of a 2 mol / L formaldehyde aqueous solution to 45-180 g of deionized water, stir and reflux at 60-90° C. for 8-16 h, and after the reaction is complete, centrifuge, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain phosphate-modified carbon nanotubes; (3) Add 0.1 g of phosphate-modified carbon nanotubes and 0.02-0.05 g of catalyst urea to 40-80 g of deionized water, then add 0.1-0.35 g of starch, perform ultrasonic treatment for 15-30 min, heat to 50-80 ° C and react for 2-6 h, after the reaction is completed, centrifuge, wash with deionized water, and vacuum dry to obtain flame-retardant functionalized carbon nanotubes; (4) Add 100 g of low-density polyethylene, 0.6-1 g of flame-retardant functionalized carbon nanotubes, 1-2 g of stearic acid and 0.5-1.5 g of antioxidant 1076 into a double-roll mixer, mix at 200-240° C. for 15-45 min, and then use an injection molding machine to perform injection molding to obtain a flame-retardant functionalized carbon nanotube modified polyethylene material. Example 1

[0014] (1) Disperse 10 mg of carbon nanotubes in 10 ml of deionized water, ultrasonically treat for 10 min, then add 18 mg of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 15 mg of 1-hydroxybenzotriazole, ultrasonically treat for 30 min, then add 60 mg of 1,3-propylenediamine, and ultrasonically treat for 4 h. After the reaction is completed, wash with deionized water and acetone, and vacuum dry to obtain amino-modified carbon nanotubes; (2) Add 1.5 g of amino-modified carbon nanotubes, 0.3 g of phosphorous acid, and 0.45 g of a 2 mol / L formaldehyde aqueous solution to 45 g of deionized water, stir and reflux at 60° C. for 8 h, and after the reaction is complete, centrifuge, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain phosphate-modified carbon nanotubes; (3) Add 0.1 g of phosphate-modified carbon nanotubes and 0.02 g of catalyst urea to 40 g of deionized water, then add 0.1 g of starch, ultrasonically treat for 15 min, heat to 50 °C and react for 2 h. After the reaction is completed, centrifuge, wash with deionized water, and vacuum dry to obtain flame-retardant functionalized carbon nanotubes. (4) Add 100 g of low-density polyethylene, 0.6 g of flame-retardant functionalized carbon nanotubes, 1 g of stearic acid and 0.5 g of antioxidant 1076 into a double-roll mixer, mix at 200 °C for 15 min, and then use an injection molding machine to obtain a flame-retardant functionalized carbon nanotube modified polyethylene material. Example 2

[0015] (1) Disperse 10 mg of carbon nanotubes in 10 ml of deionized water, ultrasonically treat for 12 min, then add 20 mg of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 20 mg of 1-hydroxybenzotriazole, ultrasonically treat for 40 min, then add 70 mg of 1,3-propylenediamine, and ultrasonically treat for 5 h. After the reaction is completed, wash with deionized water and acetone, and vacuum dry to obtain amino-modified carbon nanotubes; (2) Add 1.5 g of amino-modified carbon nanotubes, 0.4 g of phosphorous acid, and 0.6 g of a 2 mol / L formaldehyde aqueous solution to 60 g of deionized water, stir and reflux at 60° C. for 10 h, and after the reaction is complete, centrifuge, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain phosphate-modified carbon nanotubes; (3) Add 0.1 g of phosphate-modified carbon nanotubes and 0.03 g of catalyst urea to 50 g of deionized water, then add 0.15 g of starch, ultrasonically treat for 18 min, heat to 60 °C for 3 h, and after the reaction is complete, centrifuge, wash with deionized water, and vacuum dry to obtain flame-retardant functionalized carbon nanotubes; (4) Add 100 g of low-density polyethylene, 0.7 g of flame-retardant functionalized carbon nanotubes, 1.2 g of stearic acid and 0.7 g of antioxidant 1076 into a double-roll mixer, mix at 210 °C for 20 min, and then use an injection molding machine to obtain a flame-retardant functionalized carbon nanotube modified polyethylene material. Example 3

[0016] (1) Disperse 10 mg of carbon nanotubes in 10 ml of deionized water, ultrasonically treat for 15 min, then add 34 mg of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 30 mg of 1-hydroxybenzotriazole, ultrasonically treat for 50 min, then add 100 mg of 1,3-propylenediamine, ultrasonically treat for 6 h, after the reaction is completed, wash with deionized water and acetone, and vacuum dry to obtain amino-modified carbon nanotubes; (2) Add 1.5 g of amino-modified carbon nanotubes, 0.5 g of phosphorous acid, and 0.9 g of a 2 mol / L formaldehyde aqueous solution to 80 g of deionized water, stir and reflux at 80 °C for 12 h, and after the reaction is complete, centrifuge, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain phosphate-modified carbon nanotubes; (3) Add 0.1 g of phosphate-modified carbon nanotubes and 0.03 g of catalyst urea to 70 g of deionized water, then add 0.25 g of starch, ultrasonically treat for 20 min, heat to 70 °C and react for 4 h. After the reaction is completed, centrifuge, wash with deionized water, and vacuum dry to obtain flame-retardant functionalized carbon nanotubes. (4) Add 100 g of low-density polyethylene, 0.8 g of flame-retardant functionalized carbon nanotubes, 1.5 g of stearic acid and 1.1 g of antioxidant 1076 into a double-roll mixer, mix at 230 °C for 25 min, and then use an injection molding machine to obtain a flame-retardant functionalized carbon nanotube modified polyethylene material. Example 4

[0017] (1) Disperse 10 mg of carbon nanotubes in 10 ml of deionized water, and ultrasonically treat for 20 min. Then, add 50 mg of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 45 mg of 1-hydroxybenzotriazole, and ultrasonically treat for 90 min. Then, add 140 mg of 1,3-propylenediamine, and ultrasonically treat for 8 h. After the reaction is completed, wash with deionized water and acetone, and vacuum dry to obtain amino-modified carbon nanotubes. (2) Add 1.5 g of amino-modified carbon nanotubes, 0.75 g of phosphorous acid, and 1.4 g of a 2 mol / L formaldehyde aqueous solution to 180 g of deionized water, stir and reflux at 90° C. for 16 h, and after the reaction is complete, centrifuge, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain phosphate-modified carbon nanotubes; (3) Add 0.1 g of phosphate-modified carbon nanotubes and 0.05 g of catalyst urea to 80 g of deionized water, then add 0.35 g of starch, ultrasonically treat for 30 min, heat to 80 °C for 6 h, and after the reaction is complete, centrifuge, wash with deionized water, and vacuum dry to obtain flame-retardant functionalized carbon nanotubes; (4) Add 100 g of low-density polyethylene, 1 g of flame-retardant functionalized carbon nanotubes, 2 g of stearic acid and 1.5 g of antioxidant 1076 into a double-roll mixer, mix at 240 °C for 45 min, and then use an injection molding machine to obtain a flame-retardant functionalized carbon nanotube modified polyethylene material.

[0018] Comparative Example 1 (1) 100 g of low-density polyethylene, 0.3 g of carbon nanotubes, 1.2 g of stearic acid and 1 g of antioxidant 1076 were added to a two-roll mixer and mixed at 220° C. for 30 min. The mixture was then injection molded using an injection molding machine to obtain a carbon nanotube-modified polyethylene material.

[0019] Comparative Example 2 (1) Disperse 10 mg of carbon nanotubes in 10 ml of deionized water, ultrasonically treat for 15 min, then add 40 mg of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 30 mg of 1-hydroxybenzotriazole, ultrasonically treat for 60 min, then add 100 mg of 1,3-propylenediamine, ultrasonically treat for 6 h, after the reaction is completed, wash with deionized water and acetone, and vacuum dry to obtain amino-modified carbon nanotubes; (2) Add 1.5 g of amino-modified carbon nanotubes, 0.54 g of phosphorous acid, and 0.9 g of a 2 mol / L formaldehyde aqueous solution to 150 g of deionized water, stir and reflux at 80° C. for 12 h, and after the reaction is complete, centrifuge, wash with deionized water and anhydrous ethanol, and vacuum dry to obtain phosphate-modified carbon nanotubes; (3) Add 100 g of low-density polyethylene, 0.6 g of flame-retardant functionalized carbon nanotubes, 1.2 g of stearic acid and 1 g of antioxidant 1076 into a double-roll mixer, mix at 220 °C for 30 min, and then use an injection molding machine to obtain a flame-retardant functionalized carbon nanotube modified polyethylene material.

[0020] The polyethylene materials prepared in Examples 1-4 and Comparative Examples 1-2 are compared as follows: The polyethylene materials prepared in the embodiment and the comparative example were respectively made into standard tensile specimens, and the test standard was GB / T 17037.2-2020 using an LDS tensile testing machine.

[0021]

[0022] The polyethylene of the embodiment and the comparative example was tested for limiting oxygen index using a K-R2406S digital oxygen index tester, and the test standard was GB / T 2406.1-2008.

[0023]

Claims

1. A flame retardant functionalized carbon nanotube modified polyethylene material, characterized in that: The method for preparing a flame retardant functionalized carbon nanotube modified polyethylene material comprises the following steps: (1) Dispersing carbon nanotubes in deionized water, ultrasonically treating for 10-20 min, then adding 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1-hydroxybenzotriazole, ultrasonically treating for 30-90 min, then adding 1,3-propylenediamine, ultrasonically treating for 4-8 h, after the reaction is completed, washing with deionized water and acetone, and vacuum drying to obtain amino-modified carbon nanotubes; (2) Adding amino-modified carbon nanotubes, phosphorous acid, and 2 mol / L formaldehyde aqueous solution into deionized water, stirring and refluxing at 60-90° C. for 8-16 h, and after the reaction is completed, centrifuging, washing with deionized water and anhydrous ethanol, and vacuum drying to obtain phosphate-modified carbon nanotubes; (3) adding phosphate-modified carbon nanotubes and catalyst urea to deionized water, then adding starch, ultrasonically treating for 15-30 min, heating to 50-80 °C for reaction for 2-6 h, and after the reaction is completed, centrifugation, deionized water washing, and vacuum drying to obtain flame-retardant functionalized carbon nanotubes; (4) Add low-density polyethylene, flame-retardant functionalized carbon nanotubes, stearic acid and antioxidant 1076 into a double-roll mixer, mix at 200-240° C. for 15-45 min, and then use an injection molding machine to injection mold to obtain a flame-retardant functionalized carbon nanotube modified polyethylene material.

2. The flame retardant functionalized carbon nanotube modified polyethylene material according to claim 1, characterized in that: In the step (1), the mass fraction of deionized water is 1000-5000 parts, the mass fraction of carbon nanotubes is 10 parts, the mass fraction of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 18-50 parts, the mass fraction of 1-hydroxybenzotriazole is 15-45 parts, and the mass fraction of 1,3-propylenediamine is 60-140 parts.

3. The flame retardant functionalized carbon nanotube modified polyethylene material according to claim 1, characterized in that: In the step (2), the mass fractions of deionized water are 3000-12000 parts, the mass fractions of amino-modified carbon nanotubes are 100 parts, the mass fractions of phosphorous acid are 20-50 parts, and the mass fractions of formaldehyde are 3-10 parts.

4. The flame retardant functionalized carbon nanotube modified polyethylene material according to claim 1, characterized in that: In the step (3), the mass fractions of deionized water are 4000-8000 parts, the mass fractions of phosphate-modified carbon nanotubes are 10 parts, the mass fractions of urea are 2-5 parts, and the mass fractions of starch are 10-35 parts.

5. The flame retardant functionalized carbon nanotube modified polyethylene material according to claim 1, characterized in that: In the step (4), the mass fraction of low-density polyethylene is 100 parts, the mass fraction of flame-retardant functionalized carbon nanotubes is 0.6-2 parts, the mass fraction of stearic acid is 1-2 parts, and the mass fraction of antioxidant 1076 is 0.5-1.5 parts.

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