CN115304823A - Application of terminal olefin-based modified nano filler and preparation method of polylactic acid composite material - Google Patents
Application of terminal olefin-based modified nano filler and preparation method of polylactic acid composite material Download PDFInfo
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Abstract
The invention belongs to the technical field of high polymer materials, and particularly relates to an application of a terminal olefin group modified nano filler and a preparation method of a polylactic acid composite material. The invention provides an application of a terminal olefin group modified nano filler as a crystallization nucleating agent in preparation of a polylactic acid composite material. According to the invention, the terminal olefin group modified nano filler is added into the polylactic acid, so that the crystallization nucleation efficiency of the polylactic acid can be improved and the crystallinity of the polylactic acid can be further improved under the condition of not adding a plasticizer.
Description
Technical Field
The invention belongs to the technical field of macromolecules, and particularly relates to application of a terminal olefin-based modified nano filler, a polylactic acid composite material and a preparation method thereof.
Background
Polylactic acid is a high molecular material with biodegradable characteristics, has the advantages of high strength, high gloss and the like, and is considered to be one of ideal substitutes for petroleum-based non-degradable high molecular materials. However, polylactic acid has a slow crystallization rate and hardly crystallizes in a general molding process, which limits the practical use of polylactic acid.
Huneault et al (Li H, huneault M A. Effect of circulation and localization on the crystallization of poly (lactic acid) -scientific direct [ J ] Polymer,2007,48 (23): 6855-6866.) use talc in conjunction with polyethylene glycol to increase the rate of crystallization of polylactic acid. The talcum powder can be used as a nucleating agent to induce the formation of polylactic acid crystal nucleus, and the polyethylene glycol can be used as a plasticizer to improve the mobility of a polylactic acid molecular chain so as to promote the crystal growth. Although this method can improve the crystallinity of polylactic acid, it requires the use of a higher content of polyethylene glycol as a plasticizer, resulting in a large decrease in the glass transition temperature of polylactic acid. And if no plasticizer is added, the single use of the talcum powder has lower improvement range on the crystallinity of the polylactic acid.
Disclosure of Invention
The invention aims to provide application of terminal olefin-based modified nano filler as a crystallization nucleating agent in preparation of a polylactic acid composite material. According to the invention, the terminal olefin modified nano filler is added into the polylactic acid, so that the crystallinity of the polylactic acid can be improved under the condition of not adding a plasticizer.
In order to achieve the above purpose, the invention provides the following technical scheme:
the invention provides an application of terminal olefin group modified nano-filler as a crystallization nucleating agent in preparation of a polylactic acid composite material.
Preferably, the terminal olefin group in the terminal olefin group-modified nanofiller includes a vinyl group or an allyl group.
Preferably, the terminal olefin-based modified nanofiller includes terminal olefin-based modified graphene and/or terminal olefin-based modified carbon nanotubes.
Preferably, the preparation method of the terminal olefin-based modified graphene comprises the following steps:
terminal olefin silane and graphene oxide dispersion liquid are mixed in a first stage, and terminal olefin-based modified graphene oxide is obtained through a first condensation reaction;
and mixing the terminal olefin-based modified graphene oxide and water in a second stage, and carrying out hydrothermal reduction to obtain the terminal olefin-based modified graphene.
Preferably, the preparation method of the terminal olefin-based modified carbon nanotube comprises the following steps:
firstly mixing the carbon nano tube, a sodium hydroxide solution and hydrogen peroxide, and carrying out substitution reaction to obtain a hydroxylated carbon nano tube;
and secondly mixing the hydroxylated carbon nanotube and terminal alkenyl silane, and carrying out a second condensation reaction to obtain the terminal alkenyl modified carbon nanotube.
The invention also provides a preparation method of the polylactic acid composite material, which comprises the following steps:
mixing polylactic acid, terminal olefin modified nano filler and organic peroxide, and mixing to obtain the polylactic acid composite material.
Preferably, the polylactic acid has a number average molecular weight of 100000 to 300000.
Preferably, the organic peroxide comprises one or more of dicumyl peroxide, di-tert-butylperoxydiisopropylbenzene and dibenzoyl peroxide.
Preferably, the mass of the terminal olefin-based modified nano filler is 1-10% of the mass of the polylactic acid composite material;
the mass of the organic peroxide is 0.1-0.8% of that of the polylactic acid composite material.
Preferably, the temperature for mixing is 180 to 230 ℃.
The invention provides an application of terminal olefin group modified nano-filler as a nucleating agent in preparation of a polylactic acid composite material. According to the invention, the terminal olefin-based modified nano filler is applied to polylactic acid as a crystallization nucleating agent, and the crystallization nucleating efficiency of the polylactic acid can be improved and the crystallinity of the polylactic acid can be further improved under the condition of not adding a plasticizer.
Drawings
FIG. 1 is a differential scanning calorimetry curve of polylactic acid composite materials obtained in examples 1 and 2 and comparative examples 1 and 2;
FIG. 2 is a graph showing the dynamic thermomechanical analysis of the polylactic acid composite materials obtained in examples 3 to 4 and comparative examples 3 to 6.
Detailed Description
The invention provides an application of terminal olefin group modified nano-filler as a crystallization nucleating agent in preparation of a polylactic acid composite material.
In the present invention, the terminal olefin group in the terminal olefin group-modified nanofiller preferably comprises a vinyl group or an allyl group.
In the invention, the terminal olefin-based modified nanofiller preferably comprises terminal olefin-based modified graphene and/or terminal olefin-based modified carbon nanotubes; when the terminal olefin-based modified nano-filler is terminal olefin-based modified graphene and terminal olefin-based modified carbon nanotubes, the ratio of the terminal olefin-based modified graphene and the terminal olefin-based modified carbon nanotubes is not particularly limited, and the terminal olefin-based modified nano-filler and the terminal olefin-based modified carbon nanotubes can be mixed according to any ratio.
In the invention, the terminal olefin-based modified graphene is preferably prepared; the preparation method preferably comprises the following steps:
firstly mixing terminal olefin silane and graphene oxide dispersion liquid, and carrying out a first condensation reaction to obtain terminal olefin-based modified graphene oxide;
and mixing the terminal olefin-based modified graphene oxide and water in a second stage, and carrying out hydrothermal reduction to obtain the terminal olefin-based modified graphene.
In the present invention, all the starting materials for the preparation are commercially available products well known to those skilled in the art, unless otherwise specified.
According to the invention, terminal olefin silane and graphene oxide dispersion liquid are mixed at first stage, and terminal olefin modified graphene oxide is obtained through a first condensation reaction.
In the present invention, the terminal olefinic group in the terminal alkenylsilane preferably includes a vinyl group or an allyl group. In the present invention, the terminal alkenylsilane preferably includes trichlorosilane, vinyltriethoxysilane, and vinyltrimethoxysilane, allyltrimethylsilane, or allyltrimethoxysilane.
In the present invention, the concentration of graphene oxide in the graphene oxide dispersion liquid is preferably 2 to 10mg/mL, more preferably 3 to 9mg/mL, and even more preferably 4 to 8mg/mL; the thickness of the graphene oxide sheet is preferably 0.9 to 5nm, more preferably 1.5 to 4.5nm, and still more preferably 2.0 to 4.0nm. In the present invention, the amount ratio of the graphene oxide to the terminal-position alkenylsilane in the graphene oxide dispersion liquid is preferably 0.1 to 0.6g:1mL, more preferably 0.2 to 0.5g:1mL, more preferably 0.33 to 0.4g:1mL.
In the present invention, the first-stage mixing process is preferably: and dropwise adding the terminal alkenyl silane into the graphene oxide dispersion liquid which is stirred. In the present invention, the rotation speed of the stirring is preferably 200 to 1000r/min, more preferably 300 to 900r/min, and still more preferably 400 to 800r/min. In the present invention, the dropping rate is preferably 1mL/10min.
In the present invention, the temperature of the first condensation reaction is preferably 50 to 90 ℃, more preferably 55 to 85 ℃, and still more preferably 60 to 80 ℃; the time is preferably 0.5 to 8 hours, more preferably 1.0 to 7.0 hours, and still more preferably 2.0 to 6.0 hours.
In the present invention, the first condensation reaction is preferably carried out under catalysis of hydrochloric acid; the hydrochloric acid is preferably concentrated hydrochloric acid; the volume ratio of the hydrochloric acid to the terminal olefin silane is preferably 1:4 to 10, more preferably 1:5 to 9, more preferably 1:6 to 8. In the present invention, the hydrochloric acid is preferably mixed with the graphene oxide dispersion before the terminal alkenylsilane is added dropwise.
After the first condensation reaction is completed, the method preferably further comprises centrifuging the obtained reaction solution to be neutral to obtain a precipitate, wherein the precipitate is terminal olefin-based modified graphene oxide. The centrifugation process is not particularly limited in the present invention, and those familiar to those skilled in the art can be used.
After the terminal olefin-based modified graphene oxide is obtained, the terminal olefin-based modified graphene oxide and water are subjected to secondary mixing, and the terminal olefin-based modified graphene is obtained through hydrothermal reduction.
In the present invention, the amount ratio of the terminal olefin-based modified graphene oxide to water is preferably 1 to 3mg/mL, and more preferably 2mg/mL.
The process of the second mixing is not particularly limited in the present invention, and may be any process known to those skilled in the art.
In the present invention, the temperature of the hydrothermal reduction is preferably 90 to 180 ℃; more preferably 100 to 170 ℃, and still more preferably 110 to 160 ℃; the time is preferably 1 to 6 hours, more preferably 2 to 5 hours, and still more preferably 3 to 4 hours. In the present invention, the hydrothermal reduction is preferably carried out in a stainless steel reaction vessel with a polytetrafluoroethylene lining.
After the hydrothermal reduction is completed, the invention preferably further comprises cooling the obtained product to room temperature and then carrying out freeze drying to obtain the terminal olefin-based modified graphene. The cooling and freeze-drying processes are not particularly limited in the present invention and may be those well known to those skilled in the art.
In the present invention, the terminal olefin-based modified carbon nanotube is preferably prepared; the preparation method preferably comprises the following steps:
firstly mixing the carbon nano tube, a sodium hydroxide solution and hydrogen peroxide, and carrying out substitution reaction to obtain a hydroxylated carbon nano tube;
and secondly mixing the hydroxylated carbon nanotube, water and terminal alkenyl silane, and carrying out a second condensation reaction to obtain the terminal alkenyl modified carbon nanotube.
In the present invention, the carbon nanotubes are preferably multi-walled carbon nanotubes or single-walled carbon nanotubes; the pipe diameter of the carbon nano tube is preferably 10-50 nm, more preferably 15-45 nm, and more preferably 20-40 nm; the aspect ratio is preferably 200 to 1000:1, more preferably 300 to 900:1, more preferably 400 to 800:1.
in the present invention, the mass concentration of the sodium hydroxide solution is preferably 1 to 10mol/L, more preferably 2 to 9mol/L, and still more preferably 3 to 8mol/L. In the present invention, the mass concentration of hydrogen peroxide is preferably 30%.
In the present invention, the ratio of the amount of the carbon nanotubes to the sodium hydroxide solution is preferably 0.5 to 5mg:1mL, more preferably 1.0 to 4.5mg:1mL, more preferably 1.5 to 4.0mg/mL. In the invention, the volumes of the sodium hydroxide solution and the hydrogen peroxide are preferably 5-15: 1, more preferably 6 to 14:1, more preferably 7 to 13:1.
in the present invention, the first mixing process is preferably: the carbon nano tube and the sodium hydroxide solution are premixed for the first time, and hydrogen peroxide is dripped into the obtained premix.
In the present invention, the first premixing is preferably carried out under stirring; the rotation speed of the stirring is preferably 200-1000 r/min, more preferably 300-900 r/min, and even more preferably 400-800 r/min; the time is preferably 20 to 60min, more preferably 30 to 50min, and still more preferably 35 to 45min. In the present invention, the dropping rate is preferably 0.5mL/min. In the present invention, the dropwise addition is preferably performed under stirring. In the present invention, the rotation speed of the stirring is the same as the rotation speed of the first premixing, and is not described herein again.
In the present invention, the temperature of the substitution reaction is preferably room temperature. In the present invention, the time for the substitution reaction is preferably 12 to 48 hours, more preferably 15 to 45 hours, and still more preferably 20 to 40 hours.
After the substitution reaction is completed, the invention also preferably comprises the step of centrifuging the obtained reaction liquid to be neutral to obtain the hydroxylated carbon nanotube. The present invention is not particularly limited to the centrifugation process, and those skilled in the art will be familiar with the centrifugation process.
After the hydroxylated carbon nanotube is obtained, the hydroxylated carbon nanotube, water and terminal alkenyl silane are mixed for the second time, and the terminal alkenyl modified carbon nanotube is obtained through the second condensation reaction.
In the present invention, the kind of the terminal alkenylsilane is preferably the same as the above scheme, and will not be described herein. In the present invention, the amount ratio of the hydroxylated carbon nanotubes to the water is preferably 5 to 20mg:1mL, more preferably 8 to 18mg:1mL, more preferably 10 to 15mg:1mL. In the present invention, the amount ratio of the hydroxylated carbon nanotubes to the terminal alkenylsilane is preferably 0.05 to 0.5g:1mL, more preferably 0.1 to 0.4g:1mL, more preferably 0.2 to 0.3g:1mL.
In the present invention, the second mixing process is preferably: and carrying out second premixing on the hydroxylated carbon nanotube and water, and dripping the terminal olefin silane into the obtained premix.
In the present invention, the second premixing is preferably carried out under stirring; the rotation speed of the stirring is preferably 200-1000 r/min, more preferably 300-900 r/min, and even more preferably 400-800 r/min; the time is preferably 15 to 60min, more preferably 20 to 55min, and still more preferably 25 to 50min. In the present invention, the dropping rate is preferably 1mL/10min. In the present invention, the dropwise addition is preferably performed under stirring. In the present invention, the rotation speed of the stirring is the same as the rotation speed of the second premixing, and the details are not repeated herein.
In the present invention, the temperature of the second condensation reaction is preferably 50 to 90 ℃, more preferably 55 to 85 ℃, and even more preferably 60 to 80 ℃; the time is preferably 0.5 to 8 hours, more preferably 1.0 to 7.0 hours, and still more preferably 2.0 to 6.0 hours.
After the second condensation reaction is completed, the method also preferably comprises the steps of centrifuging the obtained reaction liquid to be neutral, freezing and drying, and obtaining the terminal olefin-based modified carbon nanotube after drying is completed. The centrifugation and freeze-drying process is not particularly limited in the present invention, and those well known to those skilled in the art can be used.
The invention also provides a preparation method of the polylactic acid composite material, which comprises the following steps:
mixing polylactic acid, terminal olefin modified nano filler and organic peroxide, and mixing to obtain the polylactic acid composite material.
In the present invention, the number average molecular weight of the polylactic acid is preferably 100000 to 300000g/mol, more preferably 120000 to 280000g/mol, and still more preferably 150000 to 250000g/mol.
In the present invention, the organic peroxide preferably includes one or more of dicumyl peroxide, di-tert-butylperoxydiisopropylbenzene, and dibenzoyl peroxide; when the organic peroxide is two or more selected from the above-mentioned organic peroxides, the present invention does not specifically limit the proportion of the specific substance, and the organic peroxide may be mixed in any proportion.
In the present invention, the mass of the terminal olefin-based modified nanofiller is preferably 1% to 10%, more preferably 2% to 9%, and still more preferably 3% to 8% of the mass of the polylactic acid composite.
In the present invention, the mass of the organic peroxide is preferably 0.1% to 0.8%, more preferably 0.2% to 0.7%, and still more preferably 0.3% to 0.5% of the mass of the polylactic acid composite material.
In the present invention, the mixing is preferably performed in a dry mixing manner. In the present invention, the dry blending is preferably carried out under stirring. In a specific embodiment of the present invention, the dry blending process preferably comprises: mixing and dissolving organic peroxide and ethanol, and then dry-mixing with polylactic acid and terminal olefin-based modified nano-filler. In the present invention, the amount ratio of the organic peroxide to ethanol is preferably 0.1 to 0.5g:1mL, more preferably 0.2 to 0.4g:1mL, more preferably 0.3g:1mL. The invention has no special requirements on the condition parameters of the dry mixing, as long as the dry mixing can be uniformly mixed.
In the present invention, the temperature for kneading is preferably 180 to 230 ℃, more preferably 190 to 220 ℃, and still more preferably 200 to 210 ℃. In the present invention, the mixing is preferably carried out in a twin-screw extruder; the screw rotating speed of the double-screw extruder is preferably 30 to 150r/min, more preferably 40 to 140r/min, and even more preferably 50 to 130r/min.
After the mixing is completed, the invention also preferably comprises cooling and granulating the obtained material. The present invention does not require any particular cooling or pelletizing process, as is well known to those skilled in the art.
In order to further illustrate the present invention, the following detailed description of the preparation method of a polylactic acid composite material provided by the present invention is made with reference to the accompanying drawings and examples, which should not be construed as limiting the scope of the present invention.
Example 1
Stirring 500mL of graphene oxide dispersion liquid with the concentration of 2mg/mL at the stirring speed of 400r/min, and dripping 5mL of trichlorosilane at the dripping speed of 1mL/10min in the stirring process; after the dropwise addition, transferring the mixed solution into an oil bath kettle, heating to 80 ℃ for condensation reaction, wherein the reaction time is 3 hours; after the reaction is finished, centrifuging the obtained reaction liquid to be neutral to obtain vinyl modified graphene oxide;
mixing the obtained vinyl modified graphene oxide with 50mL of water, placing the mixture in a stainless steel reaction kettle with a polytetrafluoroethylene lining, and carrying out hydrothermal reduction at 150 ℃ for 3 hours; after the reaction is finished, cooling the obtained product to room temperature, and then carrying out freeze drying to obtain vinyl modified graphene;
0.5g of dicumyl peroxide and 2mL of ethanol are mixed and dissolved, and then dry-mixed with 100g of polylactic acid (the number average molecular weight is 178000 g/mol) and 5g of vinyl modified graphene; putting the obtained dry mixture into a double-screw extruder for mixing, wherein the rotating speed of screws is 80r/min, and the mixing temperature is 190 ℃; and cooling and granulating after mixing to obtain the polylactic acid composite material.
Example 2
Stirring 500mL of graphene oxide dispersion liquid with the concentration of 2mg/mL at the stirring speed of 400r/min, and dropwise adding 5mL of trichloro-vinyl silane at the dropwise adding speed of 1mL/10min in the stirring process; after the dropwise addition, transferring the mixed solution into an oil bath kettle, heating to 80 ℃ for condensation reaction, wherein the reaction time is 3 hours; after the reaction is finished, centrifuging the obtained reaction liquid to be neutral to obtain vinyl modified graphene oxide;
mixing the obtained vinyl modified graphene oxide with 50mL of water, placing the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, and carrying out hydrothermal reduction at 150 ℃ for 3 hours; after the reaction is finished, cooling the obtained product to room temperature, and then carrying out freeze drying to obtain vinyl modified graphene;
0.5g of dicumyl peroxide and 2mL of ethanol are mixed and dissolved, and then dry-mixed with 100g of polylactic acid (the number average molecular weight is 178000 g/mol) and 2g of vinyl modified graphene; putting the obtained dry mixture into a double-screw extruder for mixing, wherein the rotating speed of screws is 80r/min, and the mixing temperature is 190 ℃; and cooling and granulating after mixing to obtain the polylactic acid composite material.
Example 3
Stirring 0.5g of multi-walled carbon nanotube (the pipe diameter is 20-40 nm, the length-diameter ratio is 400-800;
stirring the obtained hydroxylated carbon nano tube and 400mL of water at the stirring speed of 500r/min for 0.5h, dropwise adding 5mL of trichlorosilane into the mixed solution under stirring, heating to 80 ℃ for reaction for 2h, centrifuging the obtained reaction solution to be neutral after the reaction is finished, and freeze-drying to obtain a vinyl modified carbon nano tube;
0.5g of dicumyl peroxide and 2mL of ethanol were mixed and dissolved, and then dry-blended with 100g of polylactic acid (number average molecular weight 178000 g/mol) and 3.5g of vinyl-modified carbon nanotubes; putting the obtained dry mixture into a double-screw extruder for mixing, wherein the rotating speed of screws is 90r/min, and the mixing temperature is 190 ℃; and cooling and granulating after mixing to obtain the polylactic acid composite material.
Example 4
Stirring 0.5g of multi-walled carbon nanotube (the pipe diameter is 20-40 nm, the length-diameter ratio is 400-800;
stirring the obtained hydroxylated carbon nano tube and 400mL of water at the stirring speed of 500r/min for 0.5h, dropwise adding 5mL of trichlorosilane into the mixed solution under stirring, heating to 80 ℃ for reaction for 2h, centrifuging the obtained reaction solution to be neutral after the reaction is finished, and freeze-drying to obtain a vinyl modified carbon nano tube;
0.5g of dicumyl peroxide and 2mL of ethanol were mixed and dissolved, and then dry-blended with 100g of polylactic acid (number average molecular weight 178000 g/mol) and 1.5g of vinyl-modified carbon nanotubes; putting the obtained dry mixture into a double-screw extruder for mixing, wherein the rotating speed of screws is 90r/min, and the mixing temperature is 190 ℃; and cooling and granulating after mixing to obtain the polylactic acid composite material.
Comparative example 1
The polylactic acid composite material is prepared according to the technical scheme of example 1, except that dicumyl peroxide is not added.
Comparative example 2
The polylactic acid composite material is prepared according to the technical scheme of the example 2, and the difference is that dicumyl peroxide is not added.
Comparative example 3
The polylactic acid composite material is prepared according to the technical scheme of the example 3, and the difference is that dicumyl peroxide is not added.
Comparative example 4
The polylactic acid composite material is prepared according to the technical scheme of the embodiment 4, and the difference is that dicumyl peroxide is not added.
Comparative example 5
0.5g of dicumyl peroxide and 2mL of ethanol were mixed and dissolved, and then dry-blended with 100g of polylactic acid (number average molecular weight 178000 g/mol) and 3.5g of unmodified carbon nanotubes; putting the obtained dry mixture into a double-screw extruder for mixing, wherein the rotating speed of screws is 90r/min, and the mixing temperature is 190 ℃; and cooling and granulating after mixing to obtain the polylactic acid composite material.
Comparative example 6
The polylactic acid composite material is prepared according to the technical scheme of the comparative example 5, and the difference is that dicumyl peroxide is not added.
Performance testing
Test example 1
The polylactic acid composite materials obtained in examples 1 to 2 and comparative examples 1 to 2 were tested by a differential scanning calorimetry analyzer, and the test methods (test conditions) were as follows: heating the sample to 220 ℃ at 30 ℃/min, keeping the temperature for 3min to eliminate thermal history, cooling to 40 ℃ at the cooling rate of 30 ℃/min, and recording the enthalpy change curve in the cooling process. The test results are shown in fig. 1.
It can be seen from fig. 1 that both example 1 and example 2 exhibited the crystallization peak of polylactic acid, but the crystallization peak of example 1 was stronger. The crystallinity of the polylactic acid composite material in the embodiment 1 and the embodiment 2 is respectively 33.6 percent and 17.3 percent through calculation; in contrast, in both comparative example 1 and comparative example 2, the crystallization peak of polylactic acid did not appear, which indicates that it is difficult for the modified graphene to effectively induce the crystallization of polylactic acid in the case where the interfacial effect is weak.
Test example 2
The polylactic acid composite materials obtained in examples 3 to 4 and comparative examples 3 to 6 were subjected to dynamic mechanical analysis test using a dynamic thermomechanical analyzer, and the test method was: the sample was raised from 25 ℃ to 120 ℃ in the tensile mode at a rate of 2 ℃/min and the change in modulus was recorded. The test results are shown in fig. 2.
It can be seen from FIG. 2 that the elastic modulus of example 3 shows a monotonically decreasing trend in the temperature range of 80 to 110 ℃; while the elastic modulus of example 4 and comparative examples 3 to 6 showed a tendency to increase and then decrease in the temperature range of 80 to 110 ℃. When the polylactic acid composite material contains high content of crystals, no cold crystallization occurs in the temperature range, so that the elastic modulus is monotonously reduced (as in example 3); when no crystal exists in the polylactic acid composite material (such as comparative examples 3-6), the polylactic acid composite material is subjected to cold crystallization in the temperature range, so that the elastic modulus is increased and then reduced; although the trend of example 4 is also a trend showing an increase and then a decrease, the elastic modulus is significantly higher than that of comparative examples 3 to 6; in example 4, the peak position where the elastic modulus increases and then decreases is shifted toward a lower temperature than in comparative examples 3 to 6. This indicates that in example 4, some of the polylactic acid crystals are present, and therefore the modulus of elasticity is higher than that in the absence of the crystals (e.g., comparative examples 3 to 6); cold crystallization (i.e., an increase in elastic modulus) can also occur at lower temperatures.
Although the present invention has been described in detail with reference to the above embodiments, it is to be understood that the present invention is not limited to the details of the embodiments, and that various modifications, additions, substitutions, and equivalents may be made without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. The terminal olefin group modified nano filler is used as a crystallization nucleating agent in the preparation of polylactic acid composite materials.
2. The use according to claim 1, wherein the terminal olefinic group in the terminal olefinic group-modified nanofiller comprises a vinyl group or an allyl group.
3. The use according to claim 2, wherein the terminal-olefin-based modified nanofiller comprises terminal-olefin-based modified graphene and/or terminal-olefin-based modified carbon nanotubes.
4. The application of claim 3, wherein the preparation method of the terminal olefin-based modified graphene comprises the following steps:
terminal olefin silane and graphene oxide dispersion liquid are mixed in a first stage, and terminal olefin-based modified graphene oxide is obtained through a first condensation reaction;
and mixing the terminal olefin-based modified graphene oxide and water in a second stage, and carrying out hydrothermal reduction to obtain the terminal olefin-based modified graphene.
5. The use according to claim 3, wherein the preparation method of the terminal olefin-based modified carbon nanotube comprises the following steps:
firstly mixing the carbon nano tube, a sodium hydroxide solution and hydrogen peroxide, and carrying out substitution reaction to obtain a hydroxylated carbon nano tube;
and secondly mixing the hydroxylated carbon nano tube and terminal alkenyl silane, and carrying out a second condensation reaction to obtain the terminal alkenyl modified carbon nano tube.
6. The preparation method of the polylactic acid composite material is characterized by comprising the following steps:
mixing polylactic acid, terminal olefin modified nano filler and organic peroxide, and mixing to obtain the polylactic acid composite material.
7. The method according to claim 6, wherein the polylactic acid has a number average molecular weight of 100000 to 300000.
8. The method according to claim 6, wherein the organic peroxide comprises one or more of dicumyl peroxide, di-t-butylperoxydiisopropylbenzene, and dibenzoyl peroxide.
9. The preparation method according to claim 6, wherein the mass of the terminal olefin-based modified nano filler is 1-10% of the mass of the polylactic acid composite material;
the mass of the organic peroxide is 0.1-0.8% of that of the polylactic acid composite material.
10. The method according to claim 6, wherein the kneading temperature is 180 to 230 ℃.
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