阅读说明：本技术 一种石墨烯增强的pp/ldpe纳米复合管材 (Graphene-enhanced PP/LDPE (polypropylene/low-density polyethylene) nano composite pipe ) 是由 陈卫丰 夏祥义 于 2021-08-24 设计创作，主要内容包括：本发明公开了一种石墨烯增强的PP/LDPE新型纳米复合管材。该纳米复合管材由聚丙烯(PP)和低密度聚乙烯LDPE)以及石墨烯三种主要成分组成,另外含有少量其它助剂,其中,PP/LDPE作为纳米复合管材的基体,而石墨烯作为复合管材的增强剂,采用本方法所制备的纳米复合管材,石墨烯能均匀地分散在聚合物基体中,极好地改善了复合管材的综合力学性能,复合管材产品的力学性能够得到较大提高。(The invention discloses a graphene-reinforced PP/LDPE novel nano composite pipe. The nano composite pipe prepared by the method has the advantages that the graphene can be uniformly dispersed in the polymer matrix, the comprehensive mechanical property of the composite pipe is well improved, and the mechanical property of the composite pipe product can be greatly improved.)

1. The novel graphene-reinforced PP/LDPE nano composite pipe is characterized by comprising three main components, namely polypropylene (PP), low-density polyethylene (LDPE) and graphene, wherein the graphene needs to be subjected to surface treatment by a coupling agent, and the composite pipe also contains a small amount of other auxiliary agents including one or more of a plasticizer, a stabilizer, an internal lubricant, an external lubricant, a flame retardant and a processing auxiliary agent, wherein the PP/LDPE serves as a matrix of the composite pipe, and the graphene serves as a reinforcing agent of the composite pipe.

2. The graphene-reinforced PP/LDPE nanocomposite pipe material as claimed in claim 1, wherein the concentration of concentrated sulfuric acid is 70-100%, preferably 98-98.3%.

3. The graphene-reinforced PP/LDPE nanocomposite pipe material as claimed in claim 1, wherein the mass ratio of concentrated sulfuric acid, graphite powder, sodium nitrate, potassium permanganate, deionized water and hydrogen peroxide is 50-170: 3-8: 1-5: 9-25: 70-270: 5-30, preferably 80-120: 4-6: 2-3: 12-20: 100-200: 15 to 25.

4. The graphene-reinforced PP/LDPE nanocomposite pipe as claimed in claim 1, wherein the coupling agent is one or more of silane coupling agents KH540, KH560, KH570, KH792, A151, A171, A172 and Si 602.

5. The graphene-reinforced PP/LDPE nanocomposite pipe material as claimed in claim 1, wherein the mass ratio of graphene to coupling agent is in the range of 40-130: 0.5-5, preferably 80-100: 2 to 3.

6. The graphene-reinforced PP/LDPE nanocomposite pipe material as claimed in claim 1, wherein the mass ratio of PP to LDPE is in the range of 40-130: 5 to 50, preferably 70 to 100: 10 to 30.

7. The graphene-reinforced PP/LDPE nanocomposite pipe material as claimed in claim 1, wherein the mass ratio of the polymer matrix formed by PP/LDPE to the surface-treated graphene is in the range of 50-130: 0.1-20, preferably 80-100: 0.5 to 15.

8. The graphene-reinforced PP/LDPE nanocomposite pipe as claimed in claim 1, wherein the small amount of additives are one or more of plasticizers, stabilizers, lubricants, coupling agents, flame retardants and processing aids.

9. The graphene-reinforced PP/LDPE nanocomposite pipe as claimed in claim 1, wherein the plasticizer is one or a mixture of dioctyl phthalate, diethyl phthalate, butyl benzyl phthalate, diethylhexyl adipate and tricresyl phosphate.

10. The graphene-reinforced PP/LDPE nanocomposite pipe material as claimed in claim 1, wherein the mass ratio of the PP/LDPE polymer matrix to the plasticizer is in the range of 40-130: 0 to 30, preferably 80 to 100: 0 to 15.

11. The graphene-reinforced PP/LDPE nanocomposite pipe as claimed in claim 1, wherein the stabilizer is one or a mixture of two of an organic tin stabilizer, a rare earth composite stabilizer and a metal soap stabilizer.

12. The graphene-reinforced PP/LDPE nanocomposite pipe material as claimed in claim 1, wherein the mass ratio of the PP/LDPE polymer matrix to the stabilizer is in the range of 40-130: 1-8, preferably 80-100: 3 to 6.

13. The graphene-reinforced PP/LDPE nanocomposite pipe as claimed in claim 1, wherein the internal lubricant is one or a mixture of calcium stearate, zinc stearate and monoglyceride stearate.

14. The graphene-reinforced PP/LDPE nanocomposite pipe material as claimed in claim 1, wherein the mass ratio of the PP/LDPE polymer matrix to the internal lubricant is in the range of 40-130: 0.1 to 1.5, preferably 80 to 100: 0.3 to 0.8.

15. The graphene-reinforced PP/LDPE nanocomposite pipe as claimed in claim 1, wherein the external lubricant is one or a mixture of polyethylene wax, olefin wax and ethylene bisstearamide.

16. The graphene-reinforced PP/LDPE nanocomposite pipe material as claimed in claim 1, wherein the mass ratio of the PP/LDPE polymer matrix to the external lubricant is in a range of 30-130: 0.2 to 1.6, preferably 80 to 100: 0.4 to 1.0.

17. The novel graphene-reinforced PP/LDPE composite pipe and the preparation method thereof as claimed in any one of claims 1 to 3, wherein the preparation method comprises the following steps:

(1) adding a certain amount of concentrated sulfuric acid into a reaction kettle, controlling the temperature to be about 0 ℃, adding a mixture of graphite powder and sodium nitrate while stirring according to the mixture ratio of claim 3, then adding potassium permanganate, reacting for 50min at 15 ℃, then heating to about 35 ℃, continuing to react for 30 mm, then adding deionized water, continuing to stir for 20min, then adding hydrogen peroxide, reacting for 10-20min, and keeping the reaction liquid bright yellow, then reducing the reaction liquid with a proper amount of hydrazine hydrate to obtain a black solution, then filtering the reaction liquid, washing with a 5% HCl solution and deionized water, and finally placing the filter cake into a drying oven at 60 ℃ for vacuum drying to obtain graphene; (2) according to the proportion of claim 5, adding graphene and a silane coupling agent into a powder surface modifying machine, carrying out surface modification on the graphene, then adding the graphene subjected to surface modification, a certain amount of PP, LDPE and other auxiliaries into a common high-speed stirring machine, carrying out high-speed mixing at the temperature of 70-110 ℃, then stirring at a low speed for 10min, and then cooling and discharging; (3) adding the obtained mixed solid material into a double-screw extruder, extruding under the process conditions that the screw rotating speed is 15-30r/min and the temperature is 170-200 ℃, then carrying out vacuum sizing, spray cooling and forming, and finally cutting at fixed length to obtain the graphene reinforced PP/LDPE novel composite pipe.

Technical Field

The invention relates to a graphene-reinforced PP/LDPE nano composite pipe in the field of composite materials, in particular to a graphene-reinforced composite pipe with excellent comprehensive mechanical properties.

Background

With the rapid development of national economy in China, the demand of various fields on PP pipes is increasing day by day in recent years. Along with the improvement of the quality of raw materials, processing equipment and process level, the product quality is greatly improved. However, since PP itself has some disadvantages, such as poor impact strength and brittleness at low temperature, its application in polymer pipes is greatly limited. Therefore, people utilize other various polymer materials, including ABS, MBS, LDPE and the like, to toughen and modify PP to prepare various composite polymer pipes, and certain effects are achieved.

In 2004, England scientists prepared sp from carbon atoms for the first time²Graphene, a novel two-dimensional atomic crystal formed by hybridized and connected monoatomic layers, has the thickness of only 0.3354 nm, and is the thinnest material found in the world at present. The graphene has a special monoatomic layer structure and novel physical properties, namely the thermal conductivity is about 5000J/(m.K.s), the forbidden band width is almost zero, the transparency is high (about 97.7 percent), particularly the strength is as high as 130 GPa, and the Young modulus (1100 GPa) and the fracture strength (125 GPa) of the graphene are equivalent to those of a carbon nano tube. Graphene and graphene derivatives thereof can play a good role in enhancing a polymer matrix, but the further improvement of the performance of the composite material is influenced due to the weak bonding force between the graphene and the polymer matrix. Therefore, the PP/LDPE polymer matrix and the graphene subjected to surface treatment are optimally designed according to the formula, and the PP/LDPE nano composite pipe enhanced by the graphene is prepared by adopting the extrusion blending technology, so that the problems are solved.

Disclosure of Invention

The invention aims to solve the defects of the PP pipe at present, prepare a nano composite pipe with good comprehensive mechanical properties and provide a preparation method thereof.

In order to improve the impact strength of the pipe, LDPE with good toughness and PP form a polymer matrix of the pipe, and in order to improve the bending strength and the tensile strength of the pipe, graphene with excellent mechanical properties is selected for reinforcing the pipe. Because the binding force between the graphene and the polymer matrix is not strong, the graphene is subjected to surface treatment by using various silane coupling agents, so that the binding force between the polymer matrix and the graphene is enhanced, and the mechanical property of the composite pipe is greatly improved. The PP/LDPE/graphene novel composite pipe prepared by the invention has excellent mechanical properties and good application prospect. The technical scheme is as follows:

(1) adding a certain amount of concentrated sulfuric acid into a reaction kettle, controlling the temperature to be about 0 ℃, and adding a mixture of graphite powder and sodium nitrate while stirring according to the mixture ratio of claim 3. Then adding a potassium permanganate solution, reacting for 50min at about 15 ℃, then heating to about 35 ℃, continuing to react for 30min, then adding deionized water, stirring for 20min, adding hydrogen peroxide according to the proportion, reacting for 10-20min, and reducing the reaction liquid with a proper amount of hydrazine hydrate to obtain a black solution. Then, the reaction solution was filtered and washed with 5% HCl solution and deionized water. And finally, placing the filter cake in a drying oven at 60 ℃ for vacuum drying to obtain the graphene. (2) According to the proportion of claim 5, adding graphene and a silane coupling agent into a powder surface modifying machine, carrying out surface modification on the graphene under the action of high-speed stirring, and discharging after stirring for 20 min. Then, adding the graphene subjected to surface modification, PP, LDPE and other auxiliaries in a certain proportion into a high-speed stirrer, mixing at a high speed for 20min at a temperature of 70-110 ℃, stirring at a low speed for 10min, and finally cooling and discharging; (3) and adding the obtained mixture into a double-screw extruder, extruding under the process conditions that the screw rotating speed is 15-30r/min and the temperature is 170-200 ℃, carrying out vacuum sizing, spraying, cooling and forming, and finally cutting at a fixed length to produce the graphene-reinforced PP/LDPE nano composite pipe.

The composite pipe is composed of three main components of polypropylene (PP), chlorinated polyethylene (LDPE) and graphene, wherein the graphene is subjected to surface treatment by a coupling agent, and the composite pipe also contains a small amount of other additives including a plasticizer, a stabilizer, an internal lubricant, an external lubricant, a processing additive and the like. The PP/LDPE is used as a matrix of the composite pipe, and the graphene is used as a reinforcing agent of the composite pipe.

The concentration of the concentrated sulfuric acid is 70-100%, and the preferred value is 98-98.3%.

The mass ratio of concentrated sulfuric acid, graphite powder, sodium nitrate, potassium permanganate, deionized water and hydrogen peroxide is 50-170: 3-8: 1-5: 9-25: 70-270: 5-30, preferably 80-120: 4-6: 2-3: 12-20: 100-200: 15 to 25.

The coupling agent is one or more of silane coupling agents KH540, KH560, KH570, KH792, A151, A171, A172 and Si 602.

The mass ratio of the graphene to the coupling agent is 40-130: 0.5-5, preferably 80-100: 2 to 3.

The mass ratio range of the PP to the LDPE is 40-130: 5 to 50, preferably 70 to 100: 10 to 30.

The mass ratio of the polymer matrix formed by the PP/LDPE to the graphene subjected to surface treatment is 50-130: 0.1-20, preferably 80-100: 0.5 to 15.

The small amount of auxiliary agent is one or more of plasticizer, stabilizer, lubricant, coupling agent, flame retardant and processing aid.

The plasticizer is one or a mixture of more of dioctyl phthalate, diethyl phthalate, butyl benzyl phthalate, diethylhexyl adipate and tricresyl phosphate.

The mass ratio of the PP/LDPE polymer matrix to the plasticizer is 40-130: 0 to 30, preferably 80 to 100: 0 to 15.

The stabilizer is one or a mixture of two of an organic tin stabilizer, a rare earth composite stabilizer, a metal soap stabilizer and a basic lead salt stabilizer.

The mass ratio of the polymer matrix to the stabilizer is 40-130: 1-8, preferably 80-100: 3 to 6.

The internal lubricant is one or a mixture of more of calcium stearate, zinc stearate and stearic acid monoglyceride.

The mass ratio of the PP/LDPE polymer matrix to the internal lubricant is 40-130: 0.1 to 1.5, preferably 80 to 100: 0.3 to 0.8.

The external lubricant is one or a mixture of polyethylene wax, olefin wax and ethylene distearamide.

The mass ratio of the PP/LDPE polymer matrix to the external lubricant is 30-130: 0.2 to 1.6, preferably 80 to 100: 0.4 to 1.0.

Compared with the prior art, the invention has the advantages that: the LDPE with good toughness is adopted to toughen the PP, and the PP and the LDPE form a polymer matrix together, so that the impact strength of the pipe can be improved. Meanwhile, in order to improve the bending strength and the tensile strength of the pipe, the pipe is reinforced by using the novel nano material graphene with excellent mechanical property. Because the graphene and the polymer have weak bonding force, the silane coupling agent is utilized to carry out surface treatment on the graphene, so that the bonding force between a polymer matrix and the graphene can be greatly enhanced, and the comprehensive performance of the nano composite pipe is greatly improved. The polymer nano composite pipe prepared by the invention has excellent tensile strength, bending strength and impact strength.

Detailed Description

Example 1

Adding 630kg of concentrated sulfuric acid into a reaction kettle, controlling the temperature to be about 0 ℃, adding a solid mixture of 16kg of graphite powder and 7kg of sodium nitrate while stirring, then adding 50kg of potassium permanganate, reacting for 50min at about 15 ℃, then heating to about 35 ℃, continuing to react for 30min, then adding 850kg of deionized water, continuing to stir for 20min, adding 55kg of hydrogen peroxide, reacting for 10-20min, and enabling the reaction solution to become bright yellow. Subsequently, the reaction solution was reduced with 1.2L of hydrazine hydrate to obtain a black solution, and then the reaction solution was filtered and washed with a 5% HCl solution and deionized water. And finally, placing the filter cake in a vacuum drying oven at 60 ℃ for full drying to obtain the graphene. Adding 6kg of graphene and 0.15kg of silane coupling agent KH550 into a continuous powder surface modifying machine, carrying out surface modification on the graphene under the action of high-speed stirring, and discharging after stirring for 20 min. Then adding the graphene subjected to surface modification, 100kg of PP, 10kg of LDPE, 5kg of basic lead salt stabilizer, 0.6kg of stearic acid and 0.5kg of paraffin into a common high-speed stirrer, mixing at a high speed for 20min within the temperature range of 70-110 ℃, then stirring at a low speed for 10min, cooling and discharging. And adding the obtained mixture into a double-screw extruder, setting the rotating speed of a screw to be 25r/min, extruding a pipe blank within the temperature range of 170 plus material barrel and mold temperature to 200 ℃, then carrying out vacuum sizing, spray cooling and forming, and finally carrying out fixed-length cutting to produce the graphene reinforced PP/LDPE nano composite pipe.

Example 2

Adding 430kg of concentrated sulfuric acid into a reaction kettle, controlling the temperature to be about zero, adding a solid mixture of 11kg of graphite powder and 6kg of sodium nitrate while stirring, then adding 35kg of potassium permanganate, reacting for 50min at about 15 ℃, then heating to about 35 ℃, continuing to react for 30min, then adding 550kg of deionized water, continuing to stir for 20min, adding 35kg of hydrogen peroxide, reacting for 10-20min, and enabling the reaction liquid to become bright yellow. Subsequently, the reaction solution was reduced with 0.9L of hydrazine hydrate to obtain a black solution, and then the reaction solution was filtered and washed with a 5% HCl solution and deionized water. And finally, placing the filter cake in a vacuum drying oven at 60 ℃ for full drying to obtain the graphene. Adding 5kg of graphene and 0.15kg of silane coupling agent KH560 into a powder surface modifying machine, carrying out surface modification on the graphene under the action of high-speed stirring, and discharging after stirring for 20 min. Then adding the graphene with the modified surface, 100kg of PP, 17kg of LDPE, 2.3kg of dioctyl phthalate, 5.2kg of basic lead salt stabilizer, 0.7kg of stearic acid and 0.6kg of paraffin into a common high-speed stirrer, mixing at a high speed for 20min at the temperature of 70-110 ℃, then stirring at a low speed for 10min, cooling and discharging. And adding the obtained mixture into a double-screw extruder, setting the rotating speed of the screw to be 30r/min, extruding the mixture within the temperature range of 170 plus one mold temperature to 200 ℃, carrying out vacuum sizing, spray cooling and forming, and finally carrying out fixed-length cutting to obtain the graphene reinforced PP/LDPE nano composite pipe.

Example 3

820kg of concentrated sulfuric acid is added into a reaction kettle, the temperature is controlled to be about zero, a solid mixture of 21kg of graphite powder and 13kg of sodium nitrate is added while stirring, 70kg of potassium permanganate is added, the reaction is carried out for 50min at about 15 ℃, then the temperature is raised to about 35 ℃, the reaction is continued for 30min, 1100kg of deionized water is added, the stirring is continued for 20min, 72kg of hydrogen peroxide is added, the reaction is carried out for 10-20min, and the reaction liquid becomes bright yellow. Subsequently, the reaction solution was reduced with 1.8L of hydrazine hydrate to obtain a black solution, and then the reaction solution was filtered and washed with a 5% HCl solution and deionized water. And finally, placing the filter cake in a vacuum drying oven at 60 ℃ for full drying to obtain the graphene. Adding 11kg of graphene and 0.28kg of silane coupling agent KH550 into a surface modifying machine, carrying out surface modification on the graphene under the action of high-speed stirring, and discharging after stirring for 20 min. And then adding the graphene with the modified surface, 90kg of PP, 13kg of LDPE, 1.2kg of dioctyl phthalate, 4.2kg of basic lead salt stabilizer, 0.45kg of stearic acid and 0.35kg of paraffin into a high-speed stirrer, mixing at a high speed for 20min within the temperature range of 80-100 ℃, then stirring at a low speed for 10min, cooling and discharging. Adding the obtained mixture into a hopper of a double-screw extruder, setting the rotating speed of a screw to be 20r/min, extruding the mixture at the temperature of a charging barrel and a die within the temperature range of 180 ℃ plus one over 200 ℃, carrying out vacuum sizing, carrying out spray cooling forming, and finally cutting at a fixed length to prepare the graphene reinforced PP/LDPE novel composite pipe.

TABLE I mechanical property of PP/LDPE nano composite pipe reinforced by graphene

Graphene reinforced PP/LDPE tubing of examples 1-3	Tensile Strength (MPa)	Tensile modulus (MPa)	Ring stiffness (KN/m 2)	Impact Strength (KJ/m 2)	Elongation at Break (%)
						1	67.7	4431	≧8	33.1	87.5
2	63.3	3973	≧5	30.7	118.6
						3	56.5	3151	≧4	29.5	179.8