Disclosure of Invention
Aiming at the situation, in order to overcome the defects of the prior art, the invention provides a degradable composite polyethylene plastic and a preparation method thereof, and in order to solve the problem of poor degradability of the polyethylene plastic, the invention provides a dopamine modified microcrystalline cellulose, polyether ether ketone/hydroxyapatite composite material and chitosan/nano silica aerogel which are added into the polyethylene, so that the degradability and mechanical property of the polyethylene plastic are improved.
In order to achieve the aim, the technical scheme adopted by the invention is that the invention provides degradable composite polyethylene plastic and a preparation method thereof, wherein the degradable composite polyethylene plastic comprises, by weight, 80-100 parts of low-density polyethylene, 8-12 parts of starch, 5-8 parts of dopamine modified microcrystalline cellulose, 10-15 parts of polyether ether ketone/hydroxyapatite composite material, 15-20 parts of chitosan/nano silica aerogel, 2-3 parts of polyethylene wax and 3-5 parts of glycerol.
Further, the preparation method of the dopamine-modified microcrystalline cellulose comprises the following steps:
Placing microcrystalline cellulose into a beaker, adding 100mL of deionized water, adjusting the pH value to 8.5 by using a hydrochloric acid buffer solution, adding dopamine, stirring for 3-4 hours at 30 ℃, centrifuging after the completion of the stirring, taking precipitate, and drying for 10 hours at 60 ℃ in a drying box to obtain the dopamine modified microcrystalline cellulose.
Further, the mass ratio of the microcrystalline cellulose to the dopamine is 1:0.3-0.4, the centrifugal rotating speed is 3000-4000rpm, and the time is 1-2h.
Further, the preparation method of the polyether-ether-ketone/hydroxyapatite composite material comprises the following steps:
Adding hydroxyapatite and polyether-ether-ketone into absolute ethyl alcohol, placing the absolute ethyl alcohol into an ultrasonic disperser for ultrasonic dispersion for 1 hour, then filtering and separating out a mixture, placing the mixture into an oven for drying at 90 ℃ for 10 hours, and mixing and extruding the mixture by a double-screw extruder to obtain the polyether-ether-ketone/hydroxyapatite composite material.
Further, the mass ratio of the hydroxyapatite to the polyether-ether-ketone is 1-2:20, the ultrasonic dispersion power is 300W, the extrusion temperature is 370-400 ℃, and the rotating speed is 60r/min.
Further, the preparation method of the chitosan/nano silica aerogel comprises the following steps:
S1, adding chitosan into 50mL of 0.2% acetic acid solution, magnetically stirring for 30min at 50 ℃ at 500r/min to obtain chitosan solution, adding nano silicon dioxide into 50mL of absolute ethyl alcohol, and stirring for 30min to obtain mixed solution;
S2, transferring the chitosan solution and the mixed solution obtained in the step S1 into a beaker, magnetically stirring for 24 hours in a water bath at 40 ℃ at 500r/min, then centrifuging at 8000r/min in a centrifuge to remove supernatant, washing and precipitating the supernatant with ethanol solution and ultrapure water in sequence until the supernatant is colorless, and then freezing the precipitate in a refrigerator at-20 ℃ for 24 hours, and freeze-drying to obtain the chitosan/nano silicon dioxide aerogel.
Further, in the step S1, the mass ratio of the chitosan to the nano silicon dioxide is 3:1-2.
The invention provides a preparation method of degradable composite polyethylene plastic, which comprises the following steps:
Uniformly stirring and mixing starch, dopamine modified microcrystalline cellulose, polyether ether ketone/hydroxyapatite composite material and chitosan/nano silicon dioxide aerogel, then adding polyethylene wax and glycerin, continuously stirring and mixing, finally adding low-density polyethylene, uniformly mixing, placing into an internal mixer for banburying, cooling and crushing after finishing, transferring into a double-screw extruder, extruding and granulating after mixing, preparing by using an injection machine, and shaping to obtain the degradable composite polyethylene plastic.
The beneficial effects obtained by the invention are as follows:
The microcrystalline cellulose is a hydrolysis product of natural cellulose, has a relatively complete crystal structure and a large length-diameter ratio, so that the microcrystalline cellulose has degradability and excellent mechanical property, dopamine can be subjected to self-oxidation under alkaline conditions to form polydopamine to be coated on the surface of the microcrystalline cellulose, the compatibility of the microcrystalline cellulose and a matrix and the dispersibility of the matrix are improved, the mechanical property of the plastic is further improved, the polyether-ether-ketone has good chemical stability, water resistance and thermal stability, the hydroxyapatite is used as a main inorganic component in a natural bone material, so that the bone material has excellent mechanical property, the hydroxyapatite is used as an inorganic filler, the mechanical property of a composite material can be improved, the comprehensive property of the plastic can be improved, the chitosan has very good degradability, but poor stability, the chitosan and the nano silicon dioxide are compounded to prepare aerogel, the aerogel is added into the polyethylene, the degradability of the plastic is improved, the porous structure of the aerogel can provide more adsorption positions for microorganisms, the aerogel is more favorable for degradation, the polyethylene wax and the glycerin effectively reduce friction between all components, the internal components are improved, and the mechanical property of the whole body is improved, and the smoothness is improved.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments, and all other embodiments obtained by those skilled in the art without making any inventive effort based on the embodiments of the present invention are within the scope of protection of the present invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, any methods and materials similar or equivalent to those described herein can be used in the present application. The preferred methods and materials described herein are illustrative only and should not be construed as limiting the application.
The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.
Example 1
The degradable composite polyethylene plastic comprises, by weight, 80 parts of low-density polyethylene, 8 parts of starch, 5 parts of dopamine modified microcrystalline cellulose, 10 parts of polyether-ether-ketone/hydroxyapatite composite material, 15 parts of chitosan/nano silica aerogel, 2 parts of polyethylene wax and 3 parts of glycerol.
The preparation method of the dopamine modified microcrystalline cellulose comprises the following steps:
placing 1g of microcrystalline cellulose into a beaker, adding 100mL of deionized water, adjusting the pH value to 8.5 by using a hydrochloric acid buffer solution, adding 0.3g of dopamine, stirring for 3 hours at 30 ℃, centrifuging to obtain precipitate after the completion of the stirring, wherein the centrifuging speed is 3000rpm, the time is 1 hour, and drying for 10 hours at 60 ℃ in a drying oven to obtain the dopamine modified microcrystalline cellulose.
The preparation method of the polyether-ether-ketone/hydroxyapatite composite material comprises the following steps:
Adding 1g of hydroxyapatite and 20g of polyether-ether-ketone into absolute ethyl alcohol, placing the absolute ethyl alcohol in an ultrasonic disperser for ultrasonic dispersion for 1 hour, performing ultrasonic dispersion for 300W, then performing suction filtration to separate out a mixture, placing the mixture in an oven for drying at 90 ℃ for 10 hours, and mixing and extruding the mixture by a double-screw extruder at the extrusion temperature of 370 ℃ and the rotating speed of 60r/min to obtain the polyether-ether-ketone/hydroxyapatite composite material.
The preparation method of the chitosan/nano silicon dioxide aerogel comprises the following steps:
S1, adding 3g of chitosan into 50mL of 0.2% acetic acid solution, magnetically stirring for 30min at 50 ℃ at 500r/min to obtain chitosan solution, adding 1g of nano silicon dioxide into 50mL of absolute ethyl alcohol, and stirring for 30min to obtain mixed solution;
S2, transferring the chitosan solution and the mixed solution obtained in the step S1 into a beaker, magnetically stirring for 24 hours in a water bath at 40 ℃ at 500r/min, then centrifuging at 8000r/min in a centrifuge to remove supernatant, washing and precipitating the supernatant with ethanol solution and ultrapure water in sequence until the supernatant is colorless, and then freezing the precipitate in a refrigerator at-20 ℃ for 24 hours, and freeze-drying to obtain the chitosan/nano silicon dioxide aerogel.
The embodiment provides a preparation method of degradable composite polyethylene plastic, which comprises the following steps:
Uniformly stirring and mixing starch, dopamine modified microcrystalline cellulose, polyether ether ketone/hydroxyapatite composite material and chitosan/nano silicon dioxide aerogel, then adding polyethylene wax and glycerin, continuously stirring and mixing, finally adding low-density polyethylene, uniformly mixing, placing into an internal mixer for banburying, cooling and crushing after finishing, transferring into a double-screw extruder, extruding and granulating after mixing, preparing by using an injection machine, and shaping to obtain the degradable composite polyethylene plastic.
Example 2
The degradable composite polyethylene plastic comprises, by weight, 100 parts of low-density polyethylene, 12 parts of starch, 8 parts of dopamine modified microcrystalline cellulose, 15 parts of a polyether-ether-ketone/hydroxyapatite composite material, 20 parts of chitosan/nano silica aerogel, 3 parts of polyethylene wax and 5 parts of glycerol.
The preparation method of the dopamine modified microcrystalline cellulose comprises the following steps:
1g of microcrystalline cellulose is placed in a beaker, 100mL of deionized water is added, the pH value is regulated to 8.5 by using hydrochloric acid buffer solution, 0.4g of dopamine is added, stirring is carried out for 4 hours at 30 ℃, the precipitate is obtained by centrifugation after the completion, the rotational speed of the centrifugation is 4000rpm, the time is 2 hours, and the dopamine modified microcrystalline cellulose is obtained by drying for 10 hours at 60 ℃ in a drying box.
The preparation method of the polyether-ether-ketone/hydroxyapatite composite material comprises the following steps:
Adding 2g of hydroxyapatite and 20g of polyether-ether-ketone into absolute ethyl alcohol, placing the absolute ethyl alcohol in an ultrasonic disperser for ultrasonic dispersion for 1 hour, performing ultrasonic dispersion for 300W, then performing suction filtration to separate out a mixture, placing the mixture in an oven for drying at 90 ℃ for 10 hours, and mixing and extruding the mixture by a double-screw extruder at the extrusion temperature of 400 ℃ and the rotating speed of 60r/min to obtain the polyether-ether-ketone/hydroxyapatite composite material.
The preparation method of the chitosan/nano silicon dioxide aerogel comprises the following steps:
S1, adding 3g of chitosan into 50mL of 0.2% acetic acid solution, magnetically stirring for 30min at 50 ℃ at 500r/min to obtain chitosan solution, adding 2g of nano silicon dioxide into 50mL of absolute ethyl alcohol, and stirring for 30min to obtain mixed solution;
S2, transferring the chitosan solution and the mixed solution obtained in the step S1 into a beaker, magnetically stirring for 24 hours in a water bath at 40 ℃ at 500r/min, then centrifuging at 8000r/min in a centrifuge to remove supernatant, washing and precipitating the supernatant with ethanol solution and ultrapure water in sequence until the supernatant is colorless, and then freezing the precipitate in a refrigerator at-20 ℃ for 24 hours, and freeze-drying to obtain the chitosan/nano silicon dioxide aerogel.
This example provides a method for preparing a degradable composite polyethylene plastic, which is performed with reference to example 1.
Example 3
The degradable composite polyethylene plastic comprises, by weight, 90 parts of low-density polyethylene, 10 parts of starch, 7 parts of dopamine modified microcrystalline cellulose, 12 parts of a polyether-ether-ketone/hydroxyapatite composite material, 17 parts of chitosan/nano silica aerogel, 2.5 parts of polyethylene wax and 4 parts of glycerol.
The preparation method of the dopamine modified microcrystalline cellulose comprises the following steps:
1g of microcrystalline cellulose is placed in a beaker, 100mL of deionized water is added, the pH value is regulated to 8.5 by using hydrochloric acid buffer solution, 0.35g of dopamine is added, stirring is carried out for 4 hours at 30 ℃, the precipitate is obtained by centrifugation after the completion, the rotational speed of the centrifugation is 4000rpm, the time is 2 hours, and the dopamine modified microcrystalline cellulose is obtained by drying for 10 hours at 60 ℃ in a drying box.
The preparation method of the polyether-ether-ketone/hydroxyapatite composite material comprises the following steps:
Adding 1.5g of hydroxyapatite and 20g of polyether-ether-ketone into absolute ethyl alcohol, placing the absolute ethyl alcohol in an ultrasonic disperser for ultrasonic dispersion for 1 hour, performing ultrasonic dispersion for 300W, then performing suction filtration to separate out a mixture, placing the mixture in an oven for drying at 90 ℃ for 10 hours, and mixing and extruding the mixture by a double-screw extruder at the extrusion temperature of 380 ℃ and the rotating speed of 60r/min to obtain the polyether-ether-ketone/hydroxyapatite composite material.
The preparation method of the chitosan/nano silicon dioxide aerogel comprises the following steps:
S1, adding 3g of chitosan into 50mL of 0.2% acetic acid solution, magnetically stirring for 30min at 50 ℃ at 500r/min to obtain chitosan solution, adding 1.5g of nano silicon dioxide into 50mL of absolute ethyl alcohol, and stirring for 30min to obtain mixed solution;
S2, transferring the chitosan solution and the mixed solution obtained in the step S1 into a beaker, magnetically stirring for 24 hours in a water bath at 40 ℃ at 500r/min, then centrifuging at 8000r/min in a centrifuge to remove supernatant, washing and precipitating the supernatant with ethanol solution and ultrapure water in sequence until the supernatant is colorless, and then freezing the precipitate in a refrigerator at-20 ℃ for 24 hours, and freeze-drying to obtain the chitosan/nano silicon dioxide aerogel.
This example provides a method for preparing a degradable composite polyethylene plastic, which is performed with reference to example 1.
Comparative example 1
This comparative example provides a degradable composite polyethylene plastic and a preparation method thereof, which is different from example 1 in that all components do not contain dopamine modified microcrystalline cellulose, and the rest components and the content of the components are the same as those in example 1.
Comparative example 2
This comparative example provides a degradable composite polyethylene plastic and a preparation method thereof, which is different from example 1 in that the polyether-ether-ketone/hydroxyapatite composite material is not contained in all components, and the rest components and the content of the components are the same as those in example 1.
Comparative example 3
The comparative example provides a degradable composite polyethylene plastic and a preparation method thereof, which are different from the example 1 in that all components do not contain chitosan/nano silica aerogel, and the rest components and the content of the components are the same as the example 1.
Experimental example
1. The degradable composite polyethylene plastics prepared in examples 1-3 and comparative examples 1-3 of the present invention were tested for tensile properties, and the specific method was referred to GB/T1040.1-2018, with a spline width of 10mm, a thickness of 4mm, and a tensile speed of 5mm/min.
2. The degradable composite polyethylene plastics prepared in examples 1-3 and comparative examples 1-3 were subjected to bending performance test, and the specific method is referred to GB/T9341-2008, the spline width is 10mm, the thickness is 4mm, and the bending speed is 2mm/min.
3. The biodegradable composite polyethylene plastics prepared in examples 1 to 3 and comparative examples 1 to 3 of the present invention were subjected to analysis and test for biodegradability, were subjected to biodegradation by landfill degradation, were taken out after 60 days, and were measured for residual mass and were calculated for degradation rate.
Degradation rate= (mass before degradation-remaining mass)/mass before degradation×100%.
4. The surface morphology of the degradable composite polyethylene plastic prepared in example 1 was observed by a scanning electron microscope.
Analysis of results
FIG. 1 is a graph showing the tensile properties of examples 1-3 and comparative examples 1-3 of the present invention, wherein the tensile strengths of examples 1-3 are 10.7MPa, 11.3MPa, and 10.1MPa, respectively, and the tensile strengths of comparative examples 1-3 are 6.2MPa, 7.1MPa, and 8.4MPa, respectively, as shown in the graph.
FIG. 2 is a graph showing the bending property test results of examples 1 to 3 and comparative examples 1 to 3 of the present invention, wherein the tensile strengths of examples 1 to 3 are 7.9MPa, 8.2MPa, and 7.6MPa, respectively, and the tensile strengths of comparative examples 1 to 3 are 5.7MPa, 5.8MPa, and 6.1MPa, respectively, as shown in the graph.
FIG. 3 is a graph showing the results of the biodegradability tests of examples 1 to 3 and comparative examples 1 to 3 of the present invention, wherein the degradation rates of examples 1 to 3 are 56.2%, 57.1% and 56.8% respectively, and the degradation rates of comparative examples 1 to 3 are 38.2%, 41.1% and 34.7% respectively, as shown in the graph.
The combination of fig. 1, fig. 2 and fig. 3 shows that the mechanical properties and degradability of polyethylene plastic are obviously improved by adding dopamine modified microcrystalline cellulose, polyether ether ketone/hydroxyapatite composite material and chitosan/nano silica aerogel.
FIG. 4 is a scanning electron microscope image of the degradable composite polyethylene plastic prepared in example 1 of the present invention.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made hereto without departing from the spirit and principles of the present invention.
The invention and its embodiments have been described above with no limitation, and the invention is illustrated in the figures of the accompanying drawings as one of its embodiments, without limitation in practice. In summary, those skilled in the art, having benefit of this disclosure, will appreciate that the invention can be practiced without the specific details disclosed herein.