CN115322545A - Uncrosslinked waste latex reinforced and toughened polylactic acid composite material and preparation method thereof - Google Patents

Uncrosslinked waste latex reinforced and toughened polylactic acid composite material and preparation method thereof Download PDF

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CN115322545A
CN115322545A CN202211030317.0A CN202211030317A CN115322545A CN 115322545 A CN115322545 A CN 115322545A CN 202211030317 A CN202211030317 A CN 202211030317A CN 115322545 A CN115322545 A CN 115322545A
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latex
polylactic acid
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dispersion liquid
acid composite
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CN115322545B (en
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徐欢
江亮
朱桂英
柯律
李欣雨
朱金佗
何新建
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China University of Mining and Technology CUMT
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2201/00—Properties
    • C08L2201/04—Antistatic
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
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    • Y02W30/62—Plastics recycling; Rubber recycling

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Abstract

The invention discloses a preparation method of a reinforced and toughened polylactic acid composite material of uncrosslinked waste latex, which comprises the following steps: adding expandable graphite and a stripping agent into water, placing the water into liquid-phase circulating high-speed shearing and grinding equipment for shearing, grinding and dispersing, and uniformly dispersing the stripping agent to obtain a dispersion liquid of the expandable graphite coated by the stripping agent; placing the graphene dispersion liquid into a microwave reaction kettle, and carrying out microwave irradiation and ultrasonic oscillation synergistic assisted expansion reaction to obtain fully-stripped and uniformly-dispersed graphene dispersion liquid; adding the waste latex into the graphene dispersion liquid, and placing the graphene dispersion liquid into a microwave reaction kettle to perform a crosslinking reaction of the latex; drying the decrosslinked latex, mixing with polylactic acid, and placing the mixture into a melt blending device for melt blending to obtain the high-strength high-toughness polylactic acid composite material. The method can efficiently and controllably realize the decrosslinking reaction of the waste latex, thereby improving the melt processing performance of the waste latex and obviously improving the comprehensive properties of the polylactic acid composite material, such as strength, toughness, conductivity and the like.

Description

Uncrosslinked waste latex reinforced and toughened polylactic acid composite material and preparation method thereof
Technical Field
The invention relates to a reinforced and toughened polylactic acid composite material obtained by efficiently decrosslinking waste latex through microwave-assisted reaction and a preparation method thereof, belonging to the technical field of solid waste resource utilization and polylactic acid high performance.
Background
With the application of latex products in the household, domestic, industrial and medical industries, a great deal of waste latex is discarded to landfill every year, and is easy to become a favorable place for propagation of vectors (such as aedes aegypti, dengue fever, chikungunya fever, zika virus and yellow fever) due to the non-degradability. And the harmful leaching liquor components can pollute underground water sources, so that the environment is seriously polluted, and simultaneously, huge waste of resources is caused.
The natural latex in the latex pillow is liquid flowing out of rubber tapping of rubber trees, is milk-white, has the solid content of 30-40 percent, and has the average rubber particle size of about 1.06 mu m. The fresh natural latex contains 27-41.3% of rubber components and 44-70% of water, and ammonia and other stabilizing agents are added to prevent the natural latex from coagulating due to the action of microorganisms and enzymes. It is also necessary to add zinc diethyldithiocarbamate, benzothiazole accelerators, sulphur containing vulcanizers, silicates and zinc oxide during foaming.
In the forming process of the latex pillow, the crosslinked structure formed in the vulcanization process makes recycling difficult, and in order to make the latex pillow have higher added value, the original three-dimensional crosslinked structure needs to be destroyed, and the fluidity of the latex pillow needs to be recovered. Some methods commonly used today are: thermomechanical, thermochemical, mechanochemical, biochemical and physical processes (microwave and ultrasound). Microwave heating is an efficient and novel material treatment technology and is widely applied to the fields of material science, food processing, analytical chemistry and the like. Since microwaves are electromagnetic waves that propagate through a material, the attendant transmission process results in the dissipation of heat from electrical energy. However, the microwave energy absorbed by a sample depends on its dielectric properties, the greater the dielectric constant and dielectric dissipation factor, the more microwave power the sample absorbs and the faster it heats up. The advantages of using microwave induced carbonization to recover carbon or solid residues from waste are therefore: compared with the high temperature of 700 to 900 ℃ in the waste carbonization process, the carbonization (or pyrolysis) effect can be realized at a relatively moderate temperature of 400 to 600 ℃. In the traditional heating method, a heat source is positioned outside carbon, heat generated by the heat source is transferred through a conduction and radiation mechanism, the surface is heated firstly and then transferred to the inside, and microwave heating provides volume heating for the inside and the outside of an object at the same time with extremely high efficiency, and meanwhile, chemicals are not involved in the heating process, so that the method is a green, environment-friendly and efficient technology.
In order to solve the global problems of nondegradable waste latex and environmental pollution, the development of a microwave-assisted environment-friendly treatment method for carrying out efficient crosslinking reaction on the waste latex is urgently needed, so that the melt processability of the latex is improved, and the waste latex is effectively applied to thermoplastic composite materials.
Disclosure of Invention
The invention aims to overcome the defects of nondegradable waste latex and environmental pollution in the prior art, provides an environment-friendly synthetic method capable of efficiently crosslinking waste latex, and improves the melt processability of the waste latex, thereby expanding the application of the waste latex in reinforced and toughened polylactic acid composite materials.
In order to solve the technical problems, the invention provides a preparation method of a reinforced and toughened polylactic acid composite material of uncrosslinked waste latex, which comprises the following steps:
s1, preparing an intercalation expandable graphite solution: adding expandable graphite and a stripping agent into water, stirring uniformly, and then putting the mixture into liquid-phase circulating high-speed shearing and grinding equipment for shearing, grinding and dispersing to ensure that the stripping agent is uniformly distributed on the surfaces of graphite flakes and among the graphite flakes to obtain a dispersion liquid in which the expandable graphite is uniformly coated by the stripping agent;
s2, preparing a graphene dispersion liquid: placing the dispersion liquid obtained in the step S1 into a microwave reaction kettle, heating to 200-260 ℃ under built-in ultrasonic oscillation, reacting for 2-10 minutes, fully expanding and stripping graphite flakes into graphene nano-sheets, and obtaining a dispersion liquid containing uniformly dispersed graphene;
s3, preparing the uncrosslinked latex: putting the waste latex into the graphene dispersion liquid obtained in the S2, putting the waste latex into a microwave reaction kettle, heating to 150-220 ℃ under a stirring state, and reacting for 30 seconds-20 minutes to obtain the de-crosslinked latex;
s4, preparing the polylactic acid composite material: and (3) drying the decrosslinked latex obtained in the step (S3) until the moisture content is lower than 0.1%, uniformly mixing the decrosslinked latex with polylactic acid, and putting the decrosslinked latex into a melt blending device for melt blending to obtain the polylactic acid composite material.
As an improvement, in the step S1, the fixed carbon content of the expandable graphite is 90-99.9%, and the size of the graphite sheet is 5μm~1500 μm, the mass fraction in the water solution is 0.5% -5%.
As an improvement, in the step S1, the stripping agent is at least one of polyvinylpyrrolidone, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, polyoxyethylene octyl phenol ether-10 and octylphenol polyoxyethylene ether, and the mass fraction is 1/200 to 1/50 of that of the expandable graphite.
As an improvement, the liquid phase circulation high-speed shearing and grinding equipment for providing grinding and dispersing effects in the step S1 is at least one of a shearing homogenizing and emulsifying machine, an in-line shearing homogenizing and emulsifying machine, a vacuum homogenizing and emulsifying machine, a pin-and-rod type sand mill and a turbine type sand mill, and the energy consumption per unit mass in the grinding and dispersing process is 0.5 to 10 kWh/kg.
As an improvement, in the step S2, the output power of the microwave reaction kettle is 200 to 5000W, and the unit mass energy consumption of built-in ultrasonic oscillation is 1 to 20 kWh/kg.
As an improvement, in the step S3, the output power of the microwave reaction kettle is 200 to 5000W, and the mass ratio of the graphene to the latex is 1/1000 to 1/50.
As an improvement, in the step S4, the melt blending equipment is at least one of a high-speed mixer, an open mill, a turnover internal mixer, a continuous internal mixer, a reciprocating screw extruder, a twin-screw extruder, a single-screw extruder, a Z-type kneader, a screw kneader, a vacuum kneader and a horizontal twin-screw mixer, the processing temperature is 80 to 265 ℃, and the energy consumption per unit mass in the melt blending process is 0.1 to 5 kWh/kg; the mass ratio of the uncrosslinked latex to the polylactic acid is 1.
The invention also provides a reinforced and toughened polylactic acid composite material prepared by the method, which has good antistatic performance and consists of polylactic acid, decrosslinked latex and graphene, wherein the tensile strength of the composite material is 50 to 70 MPa, and the impact toughness is 8 to 30 kJ/m 2 Surface resistance of 1.0X 10 8 ~9.9×10 12 Omega, volume resistivity of 1.0X 10 7 ~9.9×10 11 Ω·m。
The invention has the beneficial effects that: (1) The liquid phase circulation high-speed shearing and grinding technology can effectively grind the expandable graphite flake, and ensures that the stripping agent is uniformly dispersed and coated on the surface of the graphite flake; (2) The technology combining microwave irradiation and ultrasonic oscillation is adopted, so that the graphite flake is forced to expand at high power, and a good stripping effect is formed; (3) The waste latex is added into the dispersion liquid of the nano-sheet uniformly dispersed graphene, so that the graphene is uniformly attached to the inside of the latex, the dielectric property of the latex is effectively improved, and the absorption efficiency of microwave irradiation is improved; (4) The melt blending process with high shear rate uniformly disperses the uncrosslinked latex in the polylactic acid matrix, endows good processability, and fully peels off the graphene nanosheets to improve the conductivity of the composite material; (5) The composite material has the characteristics of high strength, high toughness, antistatic property and the like, and the preparation method reflects the characteristics of environmental protection, low cost and the like, and is favorable for expanding the application and development of the uncrosslinked waste latex in the field of multifunctional composite materials. The method has the advantages of simple production process, easy large-scale and low-cost production, and multi-functionalization of composite material products.
Drawings
FIG. 1 is a flow chart of a method for preparing a reinforced and toughened polylactic acid composite material by decrosslinking waste latex according to the present invention;
FIG. 2 is a digital photograph of samples of the waste latex (a), the uncrosslinked latex (b) and the high-strength high-toughness polylactic acid composite (c) in example 1;
FIG. 3 is a scanning electron microscope image of the uncrosslinked latex reinforced and toughened polylactic acid composite material of example 1;
fig. 4 is a scanning electron microscope image of the latex-filled polylactic acid composite of comparative example 1.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings.
Example 1
The invention provides a preparation method of a reinforced and toughened polylactic acid composite material of uncrosslinked waste latex, which comprises the following steps:
s11, preparing an intercalation expandable graphite solution: adding 0.5 part by mass of expandable graphite and 0.01 part by mass of stripping agent (sodium dodecyl benzene sulfonate) into 100 parts by mass of water, uniformly stirring, shearing, grinding and dispersing by a vacuum homogenizing emulsifying machine, and obtaining a dispersion liquid of the expandable graphite uniformly coated by the stripping agent after the unit mass energy consumption reaches 0.5 kWh/kg;
s12, preparing a graphene dispersion liquid: putting the dispersion liquid obtained in the step S11 into a microwave reaction kettle (with the output power of 200W), heating to 200 ℃, reacting for 10 minutes, fully expanding and stripping graphite flakes into graphene nano-sheets when the unit mass energy consumption of the built-in ultrasonic oscillation reaches 1 kWh/kg, and obtaining the dispersion liquid containing uniformly dispersed graphene;
s13, preparing the uncrosslinked latex: putting 500 parts by mass of waste latex into the graphene dispersion liquid obtained in the step S12, putting the waste latex into a microwave reaction kettle (with the output power of 200W), heating to 150 ℃ in a stirring state, and reacting for 20 minutes to obtain de-crosslinked latex;
s14, preparing a polylactic acid composite material: and (3) drying the decrosslinked latex obtained in the step (S13) until the water content is lower than 0.1%, uniformly mixing the decrosslinked latex with 500 parts by mass of polylactic acid, putting the decrosslinked latex into a reciprocating screw extruder for melt blending (the processing temperature is 120 to 195 ℃), and obtaining the high-strength high-toughness polylactic acid composite material after the unit mass energy consumption reaches 0.1 kWh/kg.
Example 2
The invention provides a preparation method of a reinforced and toughened polylactic acid composite material of uncrosslinked waste latex, which comprises the following steps:
s21, preparing an intercalation expandable graphite solution: adding 5 parts by mass of expandable graphite and 0.025 part by mass of stripping agent (polyoxyethylene octyl phenol ether-10) into 100 parts by mass of water, uniformly stirring, shearing, grinding and dispersing by a pin type sand mill, and obtaining dispersion liquid of the expandable graphite uniformly coated by the stripping agent after the unit mass energy consumption reaches 10 kWh/kg;
s22, preparing a graphene dispersion liquid: putting the dispersion liquid obtained in the step S21 into a microwave reaction kettle (with output power of 5000W), heating to 260 ℃, reacting for 2 minutes, fully expanding and stripping graphite flakes into graphene nano-sheets when the unit mass energy consumption of the built-in ultrasonic oscillation reaches 20 kWh/kg, and obtaining the dispersion liquid containing uniformly dispersed graphene;
s23, preparing the uncrosslinked latex: placing 250 parts by mass of waste latex into the graphene dispersion liquid obtained in S22, placing the waste latex into a microwave reaction kettle (with output power of 5000W), heating to 220 ℃ under a stirring state, and reacting for 30 seconds to obtain de-crosslinked latex;
s24, preparing the polylactic acid composite material: and (3) drying the decrosslinked latex obtained in the step (S23) until the water content is lower than 0.1%, uniformly mixing the decrosslinked latex with 250 parts by mass of polylactic acid, putting the decrosslinked latex into a turnover internal mixer for melt blending (the processing temperature is 240-265 ℃), and obtaining the high-strength high-toughness polylactic acid composite material after the unit mass energy consumption reaches 5 kWh/kg.
Example 3
The invention provides a preparation method of a reinforced and toughened polylactic acid composite material of uncrosslinked waste latex, which comprises the following steps:
s31, preparing an intercalation expandable graphite solution: adding 1 part by mass of expandable graphite and 0.01 part by mass of stripping agent (polyvinylpyrrolidone) into 100 parts by mass of water, uniformly stirring, shearing, grinding and dispersing by a turbine type sand mill, and obtaining a dispersion liquid in which the expandable graphite is uniformly coated by the stripping agent after the unit mass energy consumption reaches 2 kWh/kg;
s32, preparing a graphene dispersion liquid: putting the dispersion liquid obtained in the step S31 into a microwave reaction kettle (with the output power of 1000W), heating to 230 ℃, reacting for 5 minutes, fully expanding and stripping graphite flakes into graphene nano-sheets when the unit mass energy consumption of the built-in ultrasonic oscillation reaches 5 kWh/kg, and obtaining the dispersion liquid containing uniformly dispersed graphene;
s33, preparing the uncrosslinked latex: putting 100 parts by mass of waste latex into the graphene dispersion liquid obtained in the step S32, putting the waste latex into a microwave reaction kettle (with the output power of 1000W), heating to 190 ℃ under the stirring state, and reacting for 10 minutes to obtain the de-crosslinked latex;
s34, preparing the polylactic acid composite material: and (3) drying the decrosslinked latex obtained in the step (S33) until the water content is lower than 0.1%, uniformly mixing the decrosslinked latex with 1000 parts by mass of polylactic acid, sequentially putting the decrosslinked latex into a high-speed mixer (with the temperature of 80-100 ℃) and a continuous internal mixer (with the temperature of 140-210 ℃) for melt blending, and obtaining the high-strength high-toughness polylactic acid composite material after the energy consumption per unit mass reaches 1.5 kWh/kg.
Example 4
The invention provides a preparation method of a reinforced and toughened polylactic acid composite material of uncrosslinked waste latex, which comprises the following steps:
s41, preparing an intercalation expandable graphite solution: adding 2 parts by mass of expandable graphite and 0.03 part by mass of stripping agent (sodium dodecyl sulfate) into 100 parts by mass of water, uniformly stirring, shearing, grinding and dispersing by using a pipeline type shearing, dispersing and emulsifying machine, and obtaining a dispersion liquid of the expandable graphite uniformly coated by the stripping agent after the unit mass energy consumption reaches 5 kWh/kg;
s42, preparing a graphene dispersion liquid: putting the dispersion liquid obtained in the step S41 into a microwave reaction kettle (with the output power of 3000W), heating to 240 ℃, reacting for 6 minutes, fully expanding and stripping graphite flakes into graphene nanosheets by the energy consumption per unit mass of built-in ultrasonic oscillation reaching 10 kWh/kg, and obtaining a dispersion liquid containing uniformly dispersed graphene;
s43, preparing the uncrosslinked latex: putting 500 parts by mass of waste latex into the graphene dispersion liquid obtained in S42, putting the waste latex into a microwave reaction kettle (output power of 2000W), heating to 170 ℃ under a stirring state, and reacting for 12 minutes to obtain de-crosslinked latex;
s44, preparing the polylactic acid composite material: and (3) drying the decrosslinked latex obtained in the step (S43) until the water content is lower than 0.1%, uniformly mixing the decrosslinked latex with 7000 parts by mass of polylactic acid, sequentially putting the decrosslinked latex into a screw kneading machine (the temperature is 90-120 ℃) and a single screw extruder (the temperature is 180-240 ℃) for melt blending, and obtaining the high-strength high-toughness polylactic acid composite material after the energy consumption per unit mass reaches 3 kWh/kg.
Example 5
The invention provides a preparation method of a reinforced and toughened polylactic acid composite material of uncrosslinked waste latex, which comprises the following steps:
s51, preparing an intercalation expandable graphite solution: adding 3 parts by mass of expandable graphite and 0.025 part by mass of stripping agent (sodium dodecyl sulfate) into 100 parts by mass of water, uniformly stirring, shearing, grinding and dispersing by a shearing emulsifying homogenizer, and obtaining a dispersion liquid in which the expandable graphite is uniformly coated by the stripping agent after the unit mass energy consumption reaches 8 kWh/kg;
s52, preparing a graphene dispersion liquid: putting the dispersion liquid obtained in the step S51 into a microwave reaction kettle (output power is 4000W), heating to 250 ℃, reacting for 4 minutes, fully expanding and stripping graphite flakes into graphene nano-sheets when the unit mass energy consumption of the built-in ultrasonic oscillation reaches 6 kWh/kg, and obtaining the dispersion liquid containing uniformly dispersed graphene;
s53, preparing the uncrosslinked latex: placing 2500 parts by mass of waste latex into the graphene dispersion liquid obtained in S52, placing the waste latex into a microwave reaction kettle (with output power of 3500W), heating to 195 ℃ under a stirring state, and reacting for 7 minutes to obtain de-crosslinked latex;
s54, preparing the polylactic acid composite material: and (3) drying the decrosslinked latex obtained in the step (S53) until the water content is lower than 0.1%, uniformly mixing the decrosslinked latex with 25000 parts by mass of polylactic acid, putting the decrosslinked latex into a continuous internal mixer for melt blending (the processing temperature is 160-230 ℃), and obtaining the high-strength high-toughness polylactic acid composite material after the unit mass energy consumption reaches 2.2 kWh/kg.
Comparative example 1 (No decrosslinking reaction of waste latex)
Basically, the method of example 1 is adopted to prepare the polylactic acid composite material, except that in the present example, 500 parts by mass of waste latex is directly and uniformly mixed with 500 parts by mass of polylactic acid without any treatment, and the mixture is put into a reciprocating screw extruder to be melt-blended (the processing temperature is 120 to 195 ℃), and the polylactic acid composite material is obtained after the unit mass energy consumption reaches 0.1 kWh/kg.
Comparative example 2 (direct microwave-assisted uncrosslinked waste latex without introducing graphene)
Basically, the method of embodiment 2 is adopted to prepare the de-crosslinked waste latex and the polylactic acid composite material filled with the de-crosslinked waste latex, except that the graphene nanosheet is not introduced, the waste latex is directly subjected to microwave-assisted de-crosslinking reaction, that is, 250 parts by mass of the waste latex is put into a microwave reaction kettle (with output power of 5000W), and the temperature is raised to 220 ℃ under the stirring state, and the reaction is carried out for 30 seconds, so that the de-crosslinked latex is obtained; and drying the obtained decrosslinked latex, uniformly mixing the decrosslinked latex with 250 parts by mass of polylactic acid, putting the mixture into a turnover internal mixer for melt blending (the processing temperature is 240 to 265 ℃), and obtaining the polylactic acid composite material after the unit mass energy consumption reaches 5 kWh/kg.
Comparative example 3 (introduction of expandable graphite alone, microwave-assisted uncrosslinked waste latex)
Basically, the method of example 3 is adopted to prepare the de-crosslinked waste latex and the polylactic acid composite material filled with the de-crosslinked waste latex, except that expandable graphite is only adopted to improve the dielectric property of the waste latex, namely, 1 part by mass of the expandable graphite and 100 parts by mass of the waste latex are added into 100 parts by mass of water, stirred uniformly and then put into a microwave reaction kettle (with the output power of 1000W), and the temperature is raised to 190 ℃ under the stirring state, and the reaction is carried out for 10 minutes to obtain the de-crosslinked latex; drying the obtained decrosslinked latex, uniformly mixing the decrosslinked latex with 1000 parts by mass of polylactic acid, sequentially putting the decrosslinked latex into a high-speed mixer (the temperature is 80-100 ℃) and a continuous internal mixer (the temperature is 140-210 ℃) for melt blending, and obtaining the polylactic acid composite material after the energy consumption per unit mass reaches 1.5 kWh/kg.
Structural characterization and performance testing:
the microstructure of the quenched surface of example 1 and the microstructure of the quenched surface of comparative example 1 were observed by a field emission Scanning Electron Microscope (SEM), and the results are shown in fig. 3 and 4;
the mechanical properties and the conductivity of the composite materials obtained in examples 1 to 5 and comparative examples 1 to 3 of the present invention were tested, and the results are shown in table 1. The performance evaluation method and the test standard are as follows: the extruded and pelletized composite material was dried at 100 ℃ for 1 to 2 hours, and then test samples (each set of samples comprising 5 tensile test bars, 5 impact test bars, and 3 individual bulk resistivity test boards) were molded using an injection molding machine equipped with a standard test bar mold.
And (3) testing mechanical properties: the obtained composite material is subjected to injection molding (the molding temperature is 160-220 ℃) to obtain tensile and impact sample bars, and the tensile property of the composite material is tested by using a universal drawing machine (model 5900) of Instron corporation in America according to the plastic tensile property test standard in ASTM D638-2003 of American society for testing materials; the impact properties of the composite materials were tested according to ASTM D256-1997 Standard test method for Izod impact testing of plastics, of the American society for testing and materials. At least 3 parallel test specimens were guaranteed per group and the results were averaged.
And (3) testing electrical properties: and testing the surface resistance and the volume resistivity of the composite material according to the national standard GB/T1410-2006 test method for the volume resistivity and the surface resistivity of the solid insulating material. At least 5 replicates of each group were tested and the results averaged.
TABLE 1 mechanical and electrical property test results of the composite materials
Figure 560421DEST_PATH_IMAGE002
The same important significance is that the graphene nano sheets which are fully stripped and uniformly dispersed are introduced, so that the antistatic performance is good in examples 1 to 5, and the surface resistance is 1.0 multiplied by 10 8 ~9.9×10 12 Omega range, and volume resistivity of 1.0X 10 7 ~9.9×10 11 In the range of omega.m, it is a good antistatic material. In particular, the surface resistance of example 2 was as low as 2X 10 8 Ω and a volume resistivity as low as 5 × 10 7 Omega · m, which indicates that the very small amount of graphene nanosheets can ensure good electrical properties of the composite material in a uniformly dispersed state. However, toThe ratio of 1 to 3 is in an insulating state, and the antistatic material cannot be used.
The foregoing is only a preferred embodiment of this invention and it should be noted that modifications can be made by those skilled in the art without departing from the principle of the invention and these modifications should also be considered as the protection scope of the invention.

Claims (10)

1. A preparation method of a de-crosslinked waste latex reinforced and toughened polylactic acid composite material is characterized by comprising the following steps:
s1, preparing an intercalation expandable graphite solution: adding expandable graphite and a stripping agent into water, stirring, and then placing the mixture into liquid-phase circulating high-speed shearing and grinding equipment for shearing, grinding and dispersing to obtain a dispersion liquid of the expandable graphite coated by the stripping agent;
s2, preparing a graphene dispersion liquid: putting the dispersion liquid obtained in the step S1 into a microwave reaction kettle, heating to 200-260 ℃ under ultrasonic oscillation, and reacting for 2-10 minutes to obtain a graphene dispersion liquid;
s3, preparing the uncrosslinked latex: putting the waste latex into the graphene dispersion liquid obtained in the S2, putting the waste latex into a microwave reaction kettle, heating to 150-220 ℃, and reacting for 30 seconds-20 minutes to obtain the uncrosslinked latex;
s4, preparing the polylactic acid composite material: and (3) drying the decrosslinked latex obtained in the step (S3), mixing the dried decrosslinked latex with polylactic acid, and putting the mixture into a melt blending device for melt blending to obtain the polylactic acid composite material.
2. The method of claim 1, wherein: in the step S1, the fixed carbon content of the expandable graphite is 90-99.9%, and the size of the graphite sheet is 5μm~1500 μm, the mass fraction in the water solution is 0.5-5%.
3. The production method according to claim 1, characterized in that: in the step S1, the stripping agent is at least one of polyvinylpyrrolidone, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, polyoxyethylene octyl phenol ether-10 and octylphenol polyoxyethylene ether, and the mass fraction of the stripping agent is 1/200 to 1/50 of that of the expandable graphite.
4. The method of claim 1, wherein: the liquid phase circulation high-speed shearing and grinding equipment in the step S1 is at least one of a shearing emulsifying and emulsifying machine, a pipeline type shearing dispersing and emulsifying machine, a vacuum homogenizing and emulsifying machine, a pin-type sand mill and a turbine type sand mill, and the energy consumption per unit mass in the grinding and dispersing process is 0.5 to 10 kWh/kg.
5. The method of claim 1, wherein: in the step S2, the output power of the microwave reaction kettle is 200-5000W, and the energy consumption per unit mass of ultrasonic oscillation is 1-20 kWh/kg.
6. The production method according to claim 1, characterized in that: in the step S3, the output power of the microwave reaction kettle is 200-5000W, and the mass ratio of the graphene to the latex is 1/1000-1/50.
7. The method of claim 1, wherein: in the step S4, the uncrosslinked latex obtained in S3 is dried until the moisture content is less than 0.1%.
8. The production method according to claim 1, characterized in that: and in the step S4, the melt blending equipment is at least one of a high-speed mixer, an open mill, a turnover internal mixer, a continuous internal mixer, a reciprocating screw extruder, a twin-screw extruder, a single-screw extruder, a Z-type kneader, a screw kneader, a vacuum kneader and a horizontal twin-screw mixer, the processing temperature is 80 to 265 ℃, the energy consumption per unit mass in the melt blending process is 0.1 to 5 kWh/kg, and the mass ratio of the decrosslinked latex to the polylactic acid is 1 to 19 to 1.
9. A polylactic acid composite material obtained by the preparation method according to any one of claims 1 to 8.
10.The polylactic acid composite material according to claim 9, wherein: the polylactic acid composite material has tensile strength of 50 to 70 MPa and impact toughness of 8 to 30 kJ/m 2 Surface resistance of 1.0X 10 8 ~9.9×10 12 Omega, volume resistivity of 1.0X 10 7 ~9.9×10 11 Ω·m。
CN202211030317.0A 2022-08-26 2022-08-26 Decrosslinking waste latex reinforced and toughened polylactic acid composite material and preparation method thereof Active CN115322545B (en)

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