CN113881208A - Functionalized modified straw/polylactic acid composite material and preparation method thereof - Google Patents
Functionalized modified straw/polylactic acid composite material and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a functionalized modified straw/polylactic acid composite material which comprises the following components in parts by weight: 30-400 parts of isoleucine grafted modified straw; 100 portions and 900 portions of polylactic acid. The invention also provides a preparation method of the functionalized modified straw/polylactic acid composite material. According to the invention, the isoleucine grafted modified straw is combined with the polylactic acid, the compatibility of the two is good, the interface combination is good, and the straw/polylactic acid composite material with high mechanical strength and low water absorption performance can be obtained.
Description
Technical Field
The invention belongs to the field of composite materials, and particularly relates to a straw/polylactic acid composite material and a preparation method thereof.
Background
With the exhaustion of petroleum resources and the gradual emphasis of people on ecological environment protection, the exploration of novel resources becomes very important. Polymer wood-plastic composites with natural plant fibers as reinforcement have become a hot spot of worldwide research. Among various natural plant fibers, straw is an environment-friendly renewable resource, which has wide sources, sufficient yield and low price, and the straw resource is mostly used for producing straw artificial boards, biological energy sources, biological fertilizers and the like at present. However, in the production of artificial straw boards, the quality requirement on straws is high, the added value is not high, and the problems of high production energy consumption, high production cost and the like exist in biological energy sources and biological fertilizers, so that at present, more technical problems exist, and industrial application cannot be realized. In order to solve the problems, researchers compound the straws and plastics to prepare straw-plastic composite materials which can be applied to furniture, floors, building materials, and interior decoration of automobiles, high-speed rails and airplanes, so that the added value and the application range of the straws are improved, and the balance of ecological environment can be maintained. However, the conventional straw plastic composite material generally uses non-biodegradable plastics such as polypropylene (PP), polyethylene terephthalate (PET) and Polystyrene (PS), which also causes certain "white pollution". Therefore, compounding biodegradable polymer resin with straw is a focus and focus of attention of researchers.
The straw and the biodegradable plastic are compounded, so that on one hand, the utilization rate of the straw can be increased, and on the other hand, the effect of reducing the production cost of the biodegradable plastic can be achieved. If the straw/biodegradable high polymer composite material with excellent performance can be prepared, the popularization and application of the biodegradable plastic can be further accelerated. The biodegradable polymer is mainly used as a matrix, such as polylactic acid (PLA), Polycaprolactone (PCL), Polyhydroxyalkanoate (PHA), and the like, wherein PLA is a biodegradable polymer synthesized from only biological resources. However, cellulose, lignin and the like in the straw components are polar molecules, a large number of hydrophilic hydroxyl groups are arranged on molecular chains, and PLA is a nonpolar molecule, so that the compatibility of the PLA and the fibers is extremely poor. Therefore, the construction of the compatible interface between the straw and the PLA matrix has a decisive role in preparing the straw/PLA fully-degradable material with excellent performance.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings in the background technology and provide a functionalized modified straw/polylactic acid composite material with good interface compatibility and a preparation method thereof. In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a functionalized modified straw/polylactic acid composite material comprises the following components in parts by weight:
30-400 parts of isoleucine grafted modified straw;
100 portions and 900 portions of polylactic acid.
In the functionalized modified straw/polylactic acid composite material, preferably, the isoleucine grafted modified straw is mainly obtained by reacting 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine with straw. The modified straw has better compatibility with polylactic acid and better interface bonding strength.
As a general technical concept, the invention also provides a preparation method of the functionalized modified straw/polylactic acid composite material, which comprises the following steps:
(1) 2-ureido-4-hydroxy-6-methylpyrimidine reacts with 1, 6-diisocyanate under the action of a catalyst to obtain isocyanato end-functionalized 2-ureido-4-hydroxy-6-methylpyrimidine;
(2) reacting the isocyanato end-functionalized 2-ureido-4-hydroxy-6-methylpyrimidine obtained in the step (1) with ethylene glycol under the action of a catalyst to obtain an initiator;
(3) obtaining 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine by the initiator obtained in the step (2) and isoleucine under the action of a catalyst;
(4) uniformly mixing the 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine obtained in the step (3) with straw to obtain isoleucine grafted modified straw;
(5) and (4) mixing the isoleucine grafted modified straw obtained in the step (4) with polylactic acid, crushing, and hot-pressing to obtain the functionalized modified straw/polylactic acid composite material.
In the invention, 2-ureido-4-hydroxy-6-methylpyrimidine and isoleucine are used as main reaction parts, the 2-ureido-4-hydroxy-6-methylpyrimidine can form multiple hydrogen bond combination with straws, the isoleucine and polylactic acid have good compatibility, and the 2-ureido-4-hydroxy-6-methylpyrimidine and the isoleucine are linked by the 1, 6-diisocyanate and ethylene glycol, so that the 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine is prepared.
In the above preparation method, preferably, the weight parts of the 2-ureido-4-hydroxy-6-methylpyrimidine, the 1, 6-diisocyanate, the ethylene glycol, the isoleucine, the straw and the polylactic acid are controlled to be 8-80 parts, 40-200 parts, 20-100 parts, 10-60 parts, 30-400 parts and 100-900 parts, respectively. According to the invention, the ratio of each raw material is controlled, so that isoleucine grafted modified straw which is well matched with polylactic acid can be obtained through reaction, and the functionalized modified straw/polylactic acid composite material with more excellent comprehensive performance can be obtained through the combination of the isoleucine grafted modified straw and the polylactic acid. In the raw material ratio, the ratio of each substance needs to be accurately controlled.
In the above preparation method, preferably, in the step (1), 2-ureido-4-hydroxy-6-methylpyrimidine and 1, 6-diisocyanate are reacted under the condition of a catalyst N-methylpyrrolidone (5-30 parts), chloroform is added after the reaction, the mixed solution is slowly added dropwise into an N-heptane solution, precipitation and filtration are repeatedly performed to collect a solid, and finally the solid is dried in vacuum to obtain the isocyanato end-functionalized 2-ureido-4-hydroxy-6-methylpyrimidine.
In the above preparation method, preferably, in the step (2), 2-ureido-4-hydroxy-6-methylpyrimidine with isocyanate end functionalized is reacted with ethylene glycol under the condition of stannous octoate catalyst (5-30 parts), the reactant is directly placed in acetone solution for precipitation, the product is collected by repeated precipitation and filtration, and finally the product is placed in a vacuum oven for drying to obtain the initiator.
In the above preparation method, preferably, in the step (3), the initiator is reacted with isoleucine under the condition of catalyst stannous octoate (5-30 parts) to obtain 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine.
In the above preparation method, preferably, in the step (4), the 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine and the straw are uniformly mixed, sealed and placed for 12 hours, and then dried to obtain the isoleucine grafted modified straw.
In the above preparation method, preferably, in the step (5), isoleucine grafted modified straw and polylactic acid are mixed by a two-roll mixer to obtain a mixed product; and cooling the mixed product, crushing the mixed product into granules by a crusher, pouring the granules into a hot-pressing mould, wherein the stacking height of the granules exceeds 1mm of the mould, and the surface of the granules is uniform and flat, and finally putting the hot-pressing mould into a hot press for hot pressing to obtain the functionalized modified straw/polylactic acid composite material.
In the preparation method, preferably, the mixing temperature is 160-190 ℃, and the mixing time is 10-20 min; the hot pressing time is 8-20min, the hot pressing temperature is 160-190 ℃, and the pressure is 3-7 MPa.
According to the invention, 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine is used as a novel compatilizer modified straw/PLA composite material, and a novel straw/PLA full-biodegradable material with excellent performance is developed, so that the advantages of excellent PLA performance and low straw cost can be maintained, high value-added utilization is realized, the dependence on non-renewable petrochemical resources can be reduced, complete biodegradation of the material can be ensured, and the significance is great.
In the invention, 2-ureido-4-hydroxy-6-methylpyrimidine functional isoleucine and 2-ureido-4-hydroxy-6-methylpyrimidine belong to multiple hydrogen bond groups, and a large number of polar hydroxyls exist on the surface of the straw fiber, so that multiple hydrogen bond combination can be formed between the two, and stronger combination function between the 2-ureido-4-hydroxy-6-methylpyrimidine functional isoleucine and the straw can be ensured due to mutual superposition and synergistic effect between the multiple hydrogen bonds. The isoleucine belongs to aliphatic amino acid and has good compatibility with a polylactic acid matrix, so the 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine can play a good bridging role in the straw/polylactic acid composite material.
Compared with the prior art, the invention has the advantages that:
1. according to the invention, the isoleucine grafted modified straw is combined with the polylactic acid, the compatibility of the two is good, the interface combination is good, and the straw/polylactic acid composite material with high mechanical strength and low water absorption performance can be obtained.
2. The preparation method provided by the invention is simple in process, pollution-free, low in energy consumption and high in reaction efficiency, is a simple and efficient modification process, and the obtained modified straw/polylactic acid composite material can be fully biodegradable and is an environment-friendly material.
Detailed Description
In order to facilitate an understanding of the present invention, the present invention will be described more fully and in detail with reference to the preferred embodiments, but the scope of the present invention is not limited to the specific embodiments described below.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods. In the following comparative examples and examples, 2-ureido-4-hydroxy-6-methylpyrimidine is also known as 2-amino-4-hydroxy-6-methylpyrimidine; the producer is Shanghai leaf Biotechnology GmbH; 1, 6-diisocyanate is also known as 1, 6-hexamethylene diisocyanate.
Comparative example 1:
a straw/polylactic acid composite material comprises the following components in parts by weight:
300 parts of straw;
700 parts of polylactic resin.
The preparation method of the straw/polylactic acid composite material comprises the following steps:
(1) uniformly mixing 700 parts by weight of polylactic resin and 300 parts by weight of modified straw; mixing by a double-roller mixing mill at 180 ℃ for 10min to obtain a mixed product;
(2) cooling the mixed product, crushing the mixed product into granules by a powerful crusher, pouring the granules into a hot-pressing mold, and uniformly flattening the surface of the granules, wherein the stacking height of the granules is 1mm higher than that of the mold; slowly putting the die into a hot press, wherein the hot pressing time is 10min, the hot pressing temperature is 170 ℃, and the pressure is 6MPa, so as to obtain the straw/polylactic acid composite material.
Comparative example 2:
a functionalized modified straw/polylactic acid composite material comprises the following components in parts by weight:
300 parts of isoleucine grafted and modified straw;
700 parts of polylactic acid.
Specifically, the feed additive is prepared from the following raw materials in parts by weight:
300 parts of straw;
700 parts of polylactic resin;
and (3) 30 parts of isoleucine.
The preparation method of the functionalized modified straw/polylactic acid composite material comprises the following steps:
(1) uniformly mixing the straws and isoleucine, sealing and standing for 12 hours, and drying to obtain modified straws;
(2) uniformly mixing 700 parts by weight of polylactic resin and 300 parts by weight of modified straw; mixing by a double-roller mixing mill at 180 ℃ for 10min to obtain a mixed product;
(3) cooling the mixed product, crushing the mixed product into granules by a powerful crusher, pouring the granules into a hot-pressing mold, and uniformly flattening the surface of the granules, wherein the stacking height of the granules is 1mm higher than that of the mold; slowly putting the die into a hot press, wherein the hot pressing time is 10min, the hot pressing temperature is 170 ℃, and the pressure is 6MPa, so as to obtain the modified straw/polylactic acid composite material.
Comparative example 3:
a functionalized modified straw/polylactic acid composite material comprises the following components in parts by weight:
300 parts of modified straw;
700 parts of polylactic acid.
Specifically, the feed additive is prepared from the following raw materials in parts by weight:
300 parts of straw;
700 parts of polylactic resin;
50 parts of 2-ureido-4-hydroxy-6-methylpyrimidine;
40 parts of 1, 6-diisocyanate;
10 parts of N-methylpyrrolidone;
35 parts of ethylene glycol.
The preparation method of the functionalized modified straw/polylactic acid composite material comprises the following steps:
(1) reacting 2-ureido-4-hydroxy-6-methylpyrimidine with 1, 6-diisocyanate at 100 ℃ for 12 hours under the condition of a catalyst N-methylpyrrolidone, adding trichloromethane after reaction, slowly dripping the mixed solution into an N-heptane solution, repeatedly carrying out precipitation filtration, and finally carrying out vacuum drying on the solid at 40 ℃ for 12 hours to obtain isocyanato end functionalized 2-ureido-4-hydroxy-6-methylpyrimidine;
(2) 2-ureido-4-hydroxy-6-methylpyrimidine with isocyanic acid radical end functionalization reacts with ethylene glycol for 9 hours at the temperature of 100 ℃ under the condition of catalyst stannous octoate, the reactant is directly precipitated in acetone solution, repeated precipitation and filtration are carried out, and finally the product is dried for 6 hours in a vacuum oven at the temperature of 80 ℃ to obtain modified 2-ureido-4-hydroxy-6-methylpyrimidine;
(3) then adding the straw and the modified 2-ureido-4-hydroxy-6-methylpyrimidine, uniformly mixing, sealing and placing for 12 hours, and drying to obtain modified straw;
(4) uniformly mixing 700 parts by weight of polylactic resin and 300 parts by weight of modified straw; mixing by a double-roller mixing mill at 180 ℃ for 10min to obtain a mixed product;
(5) cooling the mixed product, crushing the mixed product into granules by a powerful crusher, pouring the granules into a hot-pressing mold, and uniformly flattening the surface of the granules, wherein the stacking height of the granules is 1mm higher than that of the mold; slowly putting the die into a hot press, wherein the hot pressing time is 10min, the hot pressing temperature is 170 ℃, and the pressure is 6MPa, so as to obtain the modified straw/polylactic acid composite material.
Example 1:
a functionalized modified straw/polylactic acid composite material comprises the following components in parts by weight:
300 parts of isoleucine grafted and modified straw;
700 parts of polylactic acid.
Specifically, the feed additive is prepared from the following raw materials in parts by weight:
300 parts of straw;
700 parts of polylactic resin;
30 parts of isoleucine;
50 parts of 2-ureido-4-hydroxy-6-methylpyrimidine;
40 parts of 1, 6-diisocyanate;
10 parts of N-methylpyrrolidone;
35 parts of ethylene glycol;
4 parts of stannous octoate.
The preparation method of the functionalized modified straw/polylactic acid composite material comprises the following steps:
(1) reacting 2-ureido-4-hydroxy-6-methylpyrimidine with 1, 6-diisocyanate at 100 ℃ for 12 hours under the condition of a catalyst N-methylpyrrolidone, adding trichloromethane after reaction, slowly dripping the mixed solution into an N-heptane solution, repeatedly carrying out precipitation filtration, and finally carrying out vacuum drying on the solid at 40 ℃ for 12 hours to obtain isocyanato end functionalized 2-ureido-4-hydroxy-6-methylpyrimidine;
(2) 2-ureido-4-hydroxy-6-methylpyrimidine with isocyanic acid radical end functionalization reacts with ethylene glycol for 9 hours at the temperature of 100 ℃ under the condition of catalyst stannous octoate, reactants are directly precipitated in acetone solution, repeated precipitation and filtration are carried out, and finally the product is dried for 6 hours in a vacuum oven at the temperature of 80 ℃ to obtain an initiator;
(3) reacting an initiator with isoleucine for 6h at 110 ℃ under the condition of a catalyst stannous octoate to obtain 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine;
(4) adding the straw and the functionalized isoleucine, uniformly mixing, sealing and standing for 12 hours, and drying to obtain modified straw;
(5) uniformly mixing 700 parts by weight of polylactic resin and 300 parts by weight of modified straw; mixing by a double-roller mixing mill at 180 ℃ for 10min to obtain a mixed product;
(6) cooling the mixed product, crushing the mixed product into granules by a powerful crusher, pouring the granules into a hot-pressing mold, and uniformly flattening the surface of the granules, wherein the stacking height of the granules is 1mm higher than that of the mold; slowly putting the die into a hot press, wherein the hot pressing time is 10min, the hot pressing temperature is 170 ℃, and the pressure is 6MPa, so as to obtain the modified straw/polylactic acid composite material.
Example 2:
a functionalized modified straw/polylactic acid composite material comprises the following components in parts by weight:
300 parts of isoleucine grafted and modified straw;
700 parts of polylactic acid.
Specifically, the feed additive is prepared from the following raw materials in parts by weight:
300 parts of straw;
700 parts of polylactic resin;
45 parts of isoleucine;
70 parts of 2-ureido-4-hydroxy-6-methylpyrimidine;
60 parts of 1, 6-diisocyanate;
12 parts of N-methylpyrrolidone;
40 parts of ethylene glycol;
6 parts of stannous octoate.
The preparation method of the functionalized modified straw/polylactic acid composite material comprises the following steps:
(1) reacting 2-ureido-4-hydroxy-6-methylpyrimidine with 1, 6-diisocyanate at 110 ℃ for 10 hours under the condition of a catalyst N-methylpyrrolidone, adding trichloromethane after reaction, slowly dripping the mixed solution into an N-heptane solution, repeatedly carrying out precipitation filtration, and finally carrying out vacuum drying on the solid at 50 ℃ for 10 hours to obtain 2-ureido-4-hydroxy-6-methylpyrimidine with isocyanic acid radical end functionalization;
(2) 2-ureido-4-hydroxy-6-methylpyrimidine with isocyanate end functionalized reacts with ethylene glycol for 8 hours at 110 ℃ under the condition of catalyst stannous octoate, the reactant is directly precipitated in acetone solution, repeated precipitation and filtration are carried out, and finally the product is dried for 8 hours in a vacuum oven at 70 ℃ to obtain an initiator;
(3) reacting an initiator with isoleucine for 10h at 110 ℃ under the condition of a catalyst stannous octoate to obtain 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine;
(4) adding the straw and the functionalized isoleucine, uniformly mixing, sealing and standing for 12 hours, and drying to obtain modified straw;
(5) uniformly mixing 700 parts by weight of polylactic resin and 300 parts by weight of modified straw; mixing by a double-roller mixing mill at 180 ℃ for 10min to obtain a mixed product;
(6) cooling the mixed product, crushing the mixed product into granules by a powerful crusher, pouring the granules into a hot-pressing mold, and uniformly flattening the surface of the granules, wherein the stacking height of the granules is 1mm higher than that of the mold; slowly putting the die into a hot press, wherein the hot pressing time is 10min, the hot pressing temperature is 170 ℃, and the pressure is 6MPa, so as to obtain the modified straw/polylactic acid composite material.
Example 3:
a functionalized modified straw/polylactic acid composite material comprises the following components in parts by weight:
300 parts of isoleucine grafted and modified straw;
700 parts of polylactic acid.
Specifically, the feed additive is prepared from the following raw materials in parts by weight:
300 parts of straw;
700 parts of polylactic resin;
60 parts of isoleucine;
80 parts of 2-ureido-4-hydroxy-6-methylpyrimidine;
65 parts of 1, 6-diisocyanate;
14 parts of N-methylpyrrolidone;
50 parts of ethylene glycol;
and 8 parts of stannous octoate.
The preparation method of the functionalized modified straw/polylactic acid composite material comprises the following steps:
(1) reacting 2-ureido-4-hydroxy-6-methylpyrimidine with 1, 6-diisocyanate at 100 ℃ for 8 hours under the condition of a catalyst N-methylpyrrolidone, adding trichloromethane after reaction, slowly dripping the mixed solution into an N-heptane solution, repeatedly carrying out precipitation filtration, and finally carrying out vacuum drying on the solid at 50 ℃ for 10 hours to obtain 2-ureido-4-hydroxy-6-methylpyrimidine with isocyanic acid radical end functionalization;
(2) 2-ureido-4-hydroxy-6-methylpyrimidine with isocyanic acid radical end functionalization reacts with ethylene glycol for 10 hours at the temperature of 100 ℃ under the condition of catalyst stannous octoate, reactants are directly precipitated in acetone solution, repeated precipitation and filtration are carried out, and finally the product is dried for 10 hours in a vacuum oven at the temperature of 60 ℃ to obtain an initiator;
(3) reacting an initiator with isoleucine for 8h at 110 ℃ under the condition of a catalyst stannous octoate to obtain 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine;
(4) adding the straw and the functionalized isoleucine, uniformly mixing, sealing and standing for 12 hours, and drying to obtain modified straw;
(5) uniformly mixing 700 parts by weight of polylactic resin and 300 parts by weight of modified straw; mixing by a double-roller mixing mill at 180 ℃ for 10min to obtain a mixed product;
(6) cooling the mixed product, crushing the mixed product into granules by a powerful crusher, pouring the granules into a hot-pressing mold, and uniformly flattening the surface of the granules, wherein the stacking height of the granules is 1mm higher than that of the mold; slowly putting the die into a hot press, wherein the hot pressing time is 10min, the hot pressing temperature is 170 ℃, and the pressure is 6MPa, so as to obtain the modified straw/polylactic acid composite material.
In order to detect the mechanical properties and the water resistance of the functionalized modified straw/polylactic acid composite material, the bending strength, the tensile elongation at break and the water absorption rate of 72h of the straw/polylactic acid composite materials of comparative examples 1-3 and examples 1-3 were respectively examined.
The bending strength of the straw/polylactic acid composite material is in accordance with the standard GB/T1449-2005 (bending performance test method of fiber reinforced plastics), the specification of a test piece is 120mm multiplied by 15mm multiplied by 4mm, the distance between supports is 64mm, and the descending speed of a pressure head is 10 mm/min. The tensile strength and the tensile elongation at break are tested according to the standard GB/T1447-2005 (tensile property test method for fiber reinforced plastics), the specification of a test piece is 80mm multiplied by 10mm multiplied by 4mm, the tensile speed is 10mm/min, and the test interval is 60 mm. The water absorption of the composite material is tested according to GB/T1034-2008 standard, a test piece is sawn into a specification of 10mm multiplied by 4mm, the test piece is dried at 70 ℃ for 6 hours and then is immersed into pure water at 20 ℃, the test piece is taken out after 72 hours, excessive water on the surface is removed by filter paper, and then weighing is started by an electronic balance. The water absorption of the composite material is calculated according to the following formula: water absorption rate (weight after water absorption-weight before water absorption)/weight before water absorption × 100%. Specific performance results are shown in table 1 below.
Table 1: performance of straw/polylactic acid composite materials of comparative examples 1-3 and examples 1-3
From the results of table 1, it can be seen that: from comparative examples 1-3 and examples 1-3, it is seen that the mechanical strength and water resistance of the 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine modified composite material (examples 1-3) are better, especially the bending strength and tensile strength are significantly better, compared to the unmodified straw/polylactic acid composite material (comparative example 1), because the 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine plays a better bridging role between the two phases of the composite material, and the superposition of multiple hydrogen bonds and the optimization of compatibility thereof cooperate to make the interface compatibility and the structural stability of the composite material better. From comparative examples 2-3 and examples 1-3, it can be seen that 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine modified more favorably than the interfacial enhancement effect of the single isoleucine modification and 2-ureido-4-hydroxy-6-methylpyrimidine modification. Comparing example 1, example 2 and example 3, it can be seen that different modification process parameters have direct influence on the mechanical strength and water resistance of the composite material, wherein the modification effect under the condition of example 2 is better. In conclusion, the 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine is utilized to form multiple hydrogen bonds to construct the straw/polylactic acid compatible interface, so that better mechanical strength and water resistance can be obtained.
Claims (10)
1. A functionalized modified straw/polylactic acid composite material is characterized by comprising the following components in parts by weight:
30-400 parts of isoleucine grafted modified straw;
100 portions and 900 portions of polylactic acid.
2. The functionalized modified straw/polylactic acid composite material according to claim 1, wherein the isoleucine grafted and modified straw is mainly obtained by reacting 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine with straw.
3. A preparation method of a functionalized modified straw/polylactic acid composite material is characterized by comprising the following steps:
(1) 2-ureido-4-hydroxy-6-methylpyrimidine reacts with 1, 6-diisocyanate under the action of a catalyst to obtain isocyanato end-functionalized 2-ureido-4-hydroxy-6-methylpyrimidine;
(2) reacting the isocyanato end-functionalized 2-ureido-4-hydroxy-6-methylpyrimidine obtained in the step (1) with ethylene glycol under the action of a catalyst to obtain an initiator;
(3) obtaining 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine by the initiator obtained in the step (2) and isoleucine under the action of a catalyst;
(4) uniformly mixing the 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine obtained in the step (3) with straw to obtain isoleucine grafted modified straw;
(5) and (4) mixing the isoleucine grafted modified straw obtained in the step (4) with polylactic acid, crushing, and hot-pressing to obtain the functionalized modified straw/polylactic acid composite material.
4. The production method as claimed in claim 3, wherein the parts by weight of the 2-ureido-4-hydroxy-6-methylpyrimidine, the 1, 6-diisocyanate, the ethylene glycol, the isoleucine, the straw and the polylactic acid are controlled to be 8 to 80 parts, 40 to 200 parts, 20 to 100 parts, 10 to 60 parts, 30 to 400 parts and 100 parts, respectively.
5. The preparation method according to claim 3 or 4, characterized in that in the step (1), 2-ureido-4-hydroxy-6-methylpyrimidine and 1, 6-diisocyanate are reacted under the condition of a catalyst N-methylpyrrolidone, trichloromethane is added after the reaction, the mixed solution is slowly and dropwise added into an N-heptane solution, precipitation and filtration are repeatedly carried out to collect a solid, and finally the solid is dried in vacuum to obtain the isocyanato end-functionalized 2-ureido-4-hydroxy-6-methylpyrimidine.
6. The preparation method according to claim 3 or 4, characterized in that in the step (2), 2-ureido-4-hydroxy-6-methylpyrimidine with isocyanate end functionalized is reacted with ethylene glycol under the condition of catalyst stannous octoate, the reactant is directly put into acetone solution for precipitation, the product is collected by repeated precipitation and filtration, and finally the product is put into a vacuum oven for drying to obtain the initiator.
7. The method according to claim 3 or 4, wherein in the step (3), the initiator is reacted with isoleucine under the condition of a catalyst stannous octoate to obtain 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine.
8. The preparation method according to claim 3 or 4, characterized in that in the step (4), the 2-ureido-4-hydroxy-6-methylpyrimidine functionalized isoleucine and the straw are uniformly mixed, sealed and placed for 8-12h, and then dried to obtain the isoleucine grafted modified straw.
9. The preparation method according to claim 3 or 4, wherein in the step (5), the isoleucine grafted modified straw and the polylactic acid are mixed by a two-roll mixer to obtain a mixed product; and cooling the mixed product, crushing the mixed product into particles by a crusher, pouring the particles into a hot-pressing mold, uniformly flattening the surface of the particles, finally putting the hot-pressing mold into a hot press, and hot-pressing to obtain the functionalized modified straw/polylactic acid composite material.
10. The method as claimed in claim 9, wherein the mixing temperature is 160-190 ℃ and the mixing time is 10-20 min; the hot pressing time is 8-20min, the hot pressing temperature is 160-190 ℃, and the pressure is 3-7 MPa.
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