CN113637295A - Lignin-modified PBAT biodegradable plastic and preparation method thereof - Google Patents
Lignin-modified PBAT biodegradable plastic and preparation method thereof Download PDFInfo
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Abstract
The invention discloses lignin modified PBAT biodegradable plastic and a preparation method thereof. The raw materials of the lignin-modified PBAT biodegradable plastic comprise, by weight, 70-85 parts of PBAT, 25-30 parts of corn starch, 26-40 parts of lignin, 2-4 parts of adipic acid and 6-10 parts of polyethylene glycol diglycidyl ether. Has the advantages that: (1) lignin is treated in a eutectic solvent in a series of ways, and the effects of oxidation resistance, ultraviolet absorption enhancement and plasticizer increase are retained to the maximum extent, so that the biodegradable plastic with high quality is prepared on the basis of reducing the cost. (2) The use of lignin and corn starch successfully replaces a larger portion of PBAT, significantly reducing costs. (3) The interface acting force between PBAT and corn starch is synergistically enhanced by utilizing a lignin mixture and a deep eutectic solvent, so that the degradation rate and the mechanical property of the plastic are improved.
Description
Technical Field
The invention relates to the technical field of plastics, in particular to lignin-modified PBAT biodegradable plastic and a preparation method thereof.
Background
The improvement of science and technology drives the pace of life to be accelerated, and the consumption of plastic products is increased linearly along with the pace of life. Most of plastic products are disposable articles which are directly discarded after being used, so that the plastic garbage is increased year by year, and the environmental pollution is continuously aggravated. Along with the enhancement of environmental protection consciousness generated by various aspects such as green economy, garbage classification and the like. How to solve the problem of inhibiting the occurrence of plastic wastes becomes one of important problems, so that the degradable environment-friendly plastic can enter the lives of people.
The copolymer (PBAT) of butanediol oxalate and butanediol terephthalate is a thermoplastic polymer which can be completely biodegraded into carbon dioxide and water, but is used for plastic products, so that the cost is high, the mechanical property is low, and the application of the copolymer is greatly limited. On the other hand, lignin and corn starch are natural compounds which are abundant, cheap and completely degradable. However, due to different properties, the plastic prepared by mixing the materials has pores and low mechanical property due to poor interface compatibility.
Therefore, on the basis of reducing the cost, the method for preparing the lignin modified PBAT biodegradable plastic has important significance on how to prepare the lignin modified PBAT biodegradable plastic with high degradation rate, good mechanical property and high quality.
Disclosure of Invention
The invention aims to provide lignin modified PBAT biodegradable plastic and a preparation method thereof, and aims to solve the problems in the background art.
In order to solve the technical problems, the invention provides the following technical scheme:
a preparation method of lignin modified PBAT biodegradable plastic comprises the following steps:
s1: dispersing lignin in a deep eutectic solvent mixed solution for pretreatment, precipitating with hot water, and performing solid-liquid separation; respectively treating solid and liquid to obtain lignin A and eutectic waste liquid;
s2: dispersing lignin A into the eutectic waste liquid again, adding lipase and adipic acid, and reacting; reducing the temperature, adding polyethylene glycol diglycidyl ether solution, stirring uniformly, dropwise adding sodium hydroxide aqueous solution, reacting, and freeze-drying to obtain a lignin mixture;
s3: sequentially adding the dried PBAT, the lignin mixture and the corn starch into a high-speed mixer for homogenization; and (3) kneading in a kneading machine, granulating, and performing injection molding to obtain the lignin modified PBAT biodegradable plastic.
Preferably, the lignin is prepared from grape seeds by an enzymatic hydrolysis method.
Preferably, the deep eutectic solvent mixed solution is a mixed solution of a deep eutectic solvent and deionized water; the deep eutectic solvent is choline chloride and lactic acid in a mass ratio of 1: 1-2: 1, and the addition amount of the deionized water is 5-10% of the mass of the lactic acid.
Preferably, the raw materials of the lignin-modified PBAT biodegradable plastic comprise, by weight, 70-85 parts of PBAT, 25-30 parts of corn starch, 26-40 parts of lignin, 2-4 parts of adipic acid and 6-10 parts of polyethylene glycol diglycidyl ether.
Optimally, in the step S1, the mass ratio of the lignin to the deep eutectic solvent mixed liquid is 0.5-1: 2-5; in step S2, the ratio of lignin A to the eutectic waste liquid is 1: 0.5-0.8.
Preferably, the specific process in step S1 is: dispersing lignin in a deep eutectic solvent mixed solution, and pretreating for 5-8 hours at the temperature of 60-140 ℃; injecting the reaction solution into hot water, stirring and precipitating, and carrying out solid-liquid separation; and drying the solid, and concentrating the liquid to obtain lignin A and eutectic waste liquid.
Preferably, the specific process in step S2 is: dispersing the lignin A into the eutectic waste liquid again, setting the temperature to be 38-60 ℃, the stirring speed to be 150-250 rmp, adding lipase and adipic acid, and reacting for 1-2 hours; reducing the temperature to 30-35 ℃, adding a polyethylene glycol diglycidyl ether solution, uniformly stirring, setting the stirring speed to 300-400 rmp, dropwise adding a sodium hydroxide aqueous solution, reacting for 1-2 hours, and freeze-drying to obtain a lignin mixture.
Preferably, the solvent of the polyethylene glycol diglycidyl ether solution is ethyl acetate.
Preferably, the homogenizing temperature in the step S3 is 100-120 ℃; the kneading temperature is 140-180 ℃.
In the technical scheme, PBAT (a copolymer of butanediol oxalate and butanediol terephthalate) belongs to thermoplastic biodegradable plastics, but the application of PBAT is greatly limited by higher cost and lower mechanical property. Therefore, the scheme adds lignin and corn starch, and both substances are natural compounds which are produced from biological materials, have low price and are very easily degraded. Because the corn starch does not have thermoplasticity, the addition amount of the corn starch is less than 8 percent when the corn starch is generally used in PBAT plastics, and when the corn starch is used, the interface action force of two substances is poor due to poor polarity, so that the prepared plastics have pores and low mechanical property; the same problem of poor interfacial force between lignin and PBAT is also present. Therefore, in the scheme, lignin is subjected to a series of treatments in a deep eutectic solvent to finally form a lignin mixture, so that the lignin mixture has the effects of oxidation resistance, ultraviolet absorptivity and a plasticizer, and the high-quality biodegradable plastic is prepared on the basis of reducing the cost.
(1) In the scheme, the added corn starch is more than 15 percent of PBAT; the antioxidant has an antioxidant effect, can enhance the antioxidant effect of the plastic, and forms a synergistic effect with the antioxidant effect generated by the lignin mixture, so that the antioxidant is not added into the plastic; its reactive cross-linking in plastics inhibits the migration of PBAT, and at the same time, due to its hydrolytic properties, synergistically increases the degradation rate. Specifically, the method comprises the following steps: under the irradiation of light, PBAT migrates and crosslinks to form an insoluble polyester network, so that the adsorption sites of biological enzymes are reduced, and the hydrolysis property of PBAT is damaged.
(2) In the scheme, the lignin is prepared by taking grape seeds as raw materials through an enzymolysis method, and active ingredients can be maximally reserved due to no high-temperature high-pressure treatment. And in some series of treatments it is possible to maximize the retention of the active ingredient, therefore the treatment is carried out in a deep eutectic solvent.
The first step is as follows: the lignin is pretreated in a deep eutectic solvent mixed solution, and is dissociated and reunited to obtain lignin A, and the solvent selectively catalyzes and dissociates aryl ether bond (beta-O-4) and carbon-carbon bond in the lignin to increase the content of phenolic hydroxyl group, thereby enhancing the polarity and the compatibility with corn starch. The added deionized water improves the viscosity of the deep eutectic solvent and promotes mass transfer, so that the amount of the deep eutectic solvent and the pretreatment time are reduced on the basis of dissociating phenolic hydroxyl groups. In the process, dehydration and acylation can occur among partial aliphatic hydroxyl groups, the molecular weight of the lignin is reduced, and the nano lignin with uniform particle size is formed. The carbon-carbon double bond formed by dehydration and the acylated group are more reactive due to the addition of water. In addition, the acylation reaction promotes the re-coagulation among the nano lignin to form nano microspheres, and the substance has higher oxidation resistance and ultraviolet absorptivity. Wherein the temperature needs to be controlled, the yield of the lignin A is higher at 100-120 ℃, and the yield is gradually reduced at 120-140 ℃, which is caused by the formation of smaller fragments formed by dissociation.
The eutectic waste liquid is dried to remove water and then is reused, and the eutectic waste liquid can be used as a chain extender because the eutectic waste liquid contains smaller fragments formed by dissociation.
Secondly, dispersing the lignin A into the eutectic waste liquid again, and reducing the solvent amount because the pretreatment is not needed; under the catalytic action of lipase in inert gas, the ester exchange is carried out with adipic acid, so that the compatibility with PBAT is enhanced by utilizing similar compatibility, and the generated lignin/hexanoate is further crosslinked with PBAT; when polyethylene glycol diglycidyl ether solution is added, the reaction is stopped; then, sodium hydroxide solution is dripped in, and the polyethylene glycol diglycidyl ether is hydrolyzed under alkaline medium to carry out in-situ modification on lignin. So that the reaction between PBAT and corn starch can be carried out due to the reactivity of the epoxy group, thereby enhancing the interface acting force between the PBAT and the corn starch. In addition, because the solvent is ethyl acetate, part of the smaller segments are extracted by the ethyl acetate to be used as a chain extender in the plastic kneading process, the crosslinking density is improved, and the tensile strength and the heat resistance are increased. In the process, sodium hydroxide and lactic acid react to form sodium lactate, and the sodium lactate can be used for food preservation and increasing the application of plastics. Meanwhile, the modified starch serves as a plasticizer of the corn starch, the self-crosslinking of the corn starch is enhanced, an interpenetrating network is formed with the PBAT, and the tensile property is improved.
In addition, in the mixing and kneading process, the choline chloride and the residual lactic acid form a eutectic solvent again, so that the eutectic solvent has the functions of a plasticizer and a compatilizer, and the compatibility among the corn starch, the PBAT and the lignin is improved. The proportion of the corn starch to the PBAT is increased in turn. Meanwhile, choline chloride is a degradable substance for promoting plant photosynthesis, and can be directly used for culturing plant fertilizers after being used for composting and degrading plastics to form green circulation.
Compared with the prior art, the invention has the following beneficial effects: (1) lignin is treated in a eutectic solvent in a series of ways, and the effects of oxidation resistance, ultraviolet absorption enhancement and plasticizer increase are retained to the maximum extent, so that the biodegradable plastic with high quality is prepared on the basis of reducing the cost. (2) The use of lignin and corn starch successfully replaces a larger portion of PBAT, significantly reducing costs. (3) The interface acting force between PBAT and corn starch is synergistically enhanced by utilizing a lignin mixture and a deep eutectic solvent, so that the degradation rate and the mechanical property of the plastic are improved.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1:
s1: dispersing lignin in a deep eutectic solvent mixed solution, and pretreating for 6 hours at the temperature of 120 ℃; injecting the reaction solution into hot water, stirring and precipitating, and carrying out solid-liquid separation; and drying the solid, and concentrating the liquid to obtain lignin A and eutectic waste liquid.
S2: dispersing lignin A into the eutectic waste liquid again, setting the temperature at 40 ℃, stirring at the speed of 200rmp, adding lipase and adipic acid, and reacting for 2 hours; reducing the temperature to 35 ℃, adding a polyethylene glycol diglycidyl ether-ethyl acetate solution, uniformly stirring, setting the stirring speed to 400rmp, dropwise adding a sodium hydroxide aqueous solution, reacting for 2 hours, and freeze-drying to obtain a lignin mixture.
S3: sequentially adding the dried PBAT, the lignin mixture and the corn starch into a high-speed mixer, and homogenizing at the temperature of 120 ℃; and (3) putting the mixture into a kneader, kneading the mixture at a set temperature of 180 ℃, granulating, and performing injection molding to obtain the lignin modified PBAT biodegradable plastic.
In the technical scheme, the deep eutectic solvent is choline chloride and lactic acid in a mass ratio of 1:1, and the addition amount of the deionized water is 10% of the mass of the lactic acid. The raw materials of the lignin-modified PBAT biodegradable plastic comprise, by weight, 80g of PBAT, 28g of corn starch, 30g of lignin, 4g of adipic acid and 10g of polyethylene glycol diglycidyl ether.
Example 2:
s1: dispersing lignin in a deep eutectic solvent mixed solution, and pretreating for 8 hours at the temperature of 100 ℃; injecting the reaction solution into hot water, stirring and precipitating, and carrying out solid-liquid separation; and drying the solid, and concentrating the liquid to obtain lignin A and eutectic waste liquid.
S2: dispersing lignin A into the eutectic waste liquid again, setting the temperature at 38 ℃ and the stirring speed at 150rmp, adding lipase and adipic acid, and reacting for 1 hour; reducing the temperature to 30 ℃, adding polyethylene glycol diglycidyl ether-ethyl acetate solution, stirring uniformly, setting the stirring speed to 400rmp, dropwise adding sodium hydroxide aqueous solution, reacting for 2 hours, and freeze-drying to obtain a lignin mixture.
S3: sequentially adding the dried PBAT, the lignin mixture and the corn starch into a high-speed mixer, and homogenizing at the temperature of 120 ℃; and (3) putting the mixture into a kneader, kneading the mixture at the set temperature of 140 ℃, granulating, and performing injection molding to obtain the lignin modified PBAT biodegradable plastic.
In the technical scheme, the deep eutectic solvent is choline chloride and lactic acid in a mass ratio of 1:1, and the addition amount of the deionized water is 5% of the mass of the lactic acid. The raw materials of the lignin-modified PBAT biodegradable plastic comprise, by weight, 70g of PBAT, 25g of corn starch, 26g of lignin, 2g of adipic acid and 6g of polyethylene glycol diglycidyl ether.
Example 3:
s1: dispersing lignin in a deep eutectic solvent mixed solution, and pretreating for 5 hours at the temperature of 140 ℃; injecting the reaction solution into hot water, stirring and precipitating, and carrying out solid-liquid separation; and drying the solid, and concentrating the liquid to obtain lignin A and eutectic waste liquid.
S2: dispersing lignin A into the eutectic waste liquid again, setting the temperature at 45 ℃ and the stirring speed at 250rmp, adding lipase and adipic acid, and reacting for 2 hours; reducing the temperature to 32 ℃, adding polyethylene glycol diglycidyl ether-ethyl acetate solution, stirring uniformly, setting the stirring speed to 300rmp, dropwise adding sodium hydroxide aqueous solution, reacting for 1 hour, and freeze-drying to obtain a lignin mixture.
S3: sequentially adding the dried PBAT, the lignin mixture and the corn starch into a high-speed mixer, and homogenizing at the temperature of 110 ℃; and (3) putting the mixture into a kneader, kneading the mixture at the set temperature of 160 ℃, granulating, and performing injection molding to obtain the lignin modified PBAT biodegradable plastic.
In the technical scheme, the deep eutectic solvent is choline chloride and lactic acid in a mass ratio of 1: 1-2: 1, and the addition amount of the deionized water is 8% of the mass of the lactic acid. The raw materials of the lignin-modified PBAT biodegradable plastic comprise, by weight, 85g of PBAT, 30g of corn starch, 40g of lignin, 3g of adipic acid and 8g of polyethylene glycol diglycidyl ether.
Comparative example 1: water is not added into the deep eutectic solvent mixed solution; the rest is similar to the embodiment 1.
S1: dispersing lignin in a deep eutectic solvent mixed solution, and pretreating for 8 hours at the temperature of 60 ℃; injecting the reaction solution into hot water, stirring and precipitating, and carrying out solid-liquid separation; and drying the solid, and concentrating the liquid to obtain lignin A and eutectic waste liquid.
S2: dispersing lignin A into the eutectic waste liquid again, setting the temperature at 40 ℃, stirring at the speed of 200rmp, adding lipase and adipic acid, and reacting for 2 hours; reducing the temperature to 35 ℃, adding a polyethylene glycol diglycidyl ether-ethyl acetate solution, uniformly stirring, setting the stirring speed to 400rmp, dropwise adding a sodium hydroxide aqueous solution, reacting for 2 hours, and freeze-drying to obtain a lignin mixture.
S3: sequentially adding the dried PBAT, the lignin mixture and the corn starch into a high-speed mixer, and homogenizing at the temperature of 120 ℃; and (3) putting the mixture into a kneader, kneading the mixture at a set temperature of 180 ℃, granulating, and performing injection molding to obtain the lignin modified PBAT biodegradable plastic.
In the technical scheme, the deep eutectic solvent is choline chloride and lactic acid in a mass ratio of 1:1, and deionized water is not added. The raw materials of the lignin-modified PBAT biodegradable plastic comprise, by weight, 80g of PBAT, 25g of corn starch, 40g of lignin, 4g of adipic acid and 7g of polyethylene glycol diglycidyl ether.
Comparative example 2: in the deep eutectic solvent mixed solution, the mass ratio of choline chloride to lactic acid is 1: 3.
S1: dispersing lignin in a deep eutectic solvent mixed solution, and pretreating for 6 hours at the temperature of 120 ℃; injecting the reaction solution into hot water, stirring and precipitating, and carrying out solid-liquid separation; and drying the solid, and concentrating the liquid to obtain lignin A and eutectic waste liquid.
S2: dispersing lignin A into the eutectic waste liquid again, setting the temperature at 40 ℃, stirring at the speed of 200rmp, adding lipase and adipic acid, and reacting for 2 hours; reducing the temperature to 35 ℃, adding a polyethylene glycol diglycidyl ether-ethyl acetate solution, uniformly stirring, setting the stirring speed to 400rmp, dropwise adding a sodium hydroxide aqueous solution, reacting for 2 hours, and freeze-drying to obtain a lignin mixture.
S3: sequentially adding the dried PBAT, the lignin mixture and the corn starch into a high-speed mixer, and homogenizing at the temperature of 120 ℃; and (3) putting the mixture into a kneader, kneading the mixture at a set temperature of 180 ℃, granulating, and performing injection molding to obtain the lignin modified PBAT biodegradable plastic.
In the technical scheme, the deep eutectic solvent is choline chloride and lactic acid in a mass ratio of 1:3, and the addition amount of the deionized water is 10% of the mass of the lactic acid. The raw materials of the lignin-modified PBAT biodegradable plastic comprise, by weight, 80g of PBAT, 28g of corn starch, 30g of lignin, 4g of adipic acid and 10g of polyethylene glycol diglycidyl ether.
Comparative example 3: the eutectic solvent was replaced with organic acid: oxalic acid; the rest is the same as in example 1.
Comparative example 4: the reaction of adipic acid in step S2 was exchanged with a polyethylene glycol diglycidyl ether step.
S1: dispersing lignin in a deep eutectic solvent mixed solution, and pretreating for 6 hours at the temperature of 120 ℃; injecting the reaction solution into hot water, stirring and precipitating, and carrying out solid-liquid separation; and drying the solid, and concentrating the liquid to obtain lignin A and eutectic waste liquid.
S2: dispersing the lignin A into the eutectic waste liquid again, setting the temperature to be 35 ℃, adding a polyethylene glycol diglycidyl ether-ethyl acetate solution, stirring uniformly, setting the stirring speed to be 400rmp, dropwise adding a sodium hydroxide aqueous solution, and reacting for 2 hours; setting the temperature at 60 ℃, stirring at 200rmp, adding lipase and adipic acid, reacting for 2 hours, and freeze-drying to obtain a lignin mixture.
S3: sequentially adding the dried PBAT, the lignin mixture and the corn starch into a high-speed mixer, and homogenizing at the temperature of 120 ℃; and (3) putting the mixture into a kneader, kneading the mixture at a set temperature of 180 ℃, granulating, and performing injection molding to obtain the lignin modified PBAT biodegradable plastic.
In the technical scheme, the deep eutectic solvent is choline chloride and lactic acid in a mass ratio of 1:3, and the addition amount of the deionized water is 10% of the mass of the lactic acid. The raw materials of the lignin-modified PBAT biodegradable plastic comprise, by weight, 80g of PBAT, 28g of corn starch, 30g of lignin, 4g of adipic acid and 10g of polyethylene glycol diglycidyl ether.
Comparative example 5: the same procedure as in example 1 was repeated except that no lignin mixture was added.
Comparative example 6: referring to the preparation method in patent CN201611193435.8, lignin modified PBAT biodegradable plastic is prepared.
Comparative example 7: the PBAT is used as a material to prepare the biodegradable plastic.
Experiment: the lignin-modified PBAT biodegradable plastic prepared in the examples 1-3 and the comparative examples 1-7 is tested. With reference to GB/T1040.2-2006, a universal electronic tensile testing machine is used for testing the tensile strength and the elongation at break of the plastic; and ultraviolet aging for 48 hours, measuring again to obtain elongation at break B, and judging the ultraviolet resistance through the reduction rate. The ultraviolet resistance of the plastic is tested according to GB/T16422.3-1997; according to GB/T16716.7-2012, the prepared plastic is put in compost, and degradation experiments are carried out under ultraviolet irradiation; testing the degradation rate after 16 weeks; the data obtained are shown below:
| examples | Tensile strength/MPa | Elongation at break/% | Elongation at break B/%) | Percent of degradation/%) |
| Example 1 | 52 | 460 | 450 | 83 |
| Example 2 | 49 | 449 | 438 | 81 |
| Example 3 | 50 | 454 | 443 | 80 |
| Comparative example 1 | 48 | 445 | 436 | 78 |
| Comparative example 2 | 45 | 435 | 415 | 73 |
| Comparative example 3 | 44 | 430 | 409 | 70 |
| Comparative example 4 | 48 | 450 | 438 | 80 |
| Comparative example 5 | 22 | 386 | 362 | 85 |
| Comparative example 6 | 46 | 438 | 417 | 51 |
| Comparative example 7 | 28 | 429 | 413 | 42 |
And (4) conclusion: from the data of examples 1-3, it can be seen that the high-content lignin and corn starch are used to replace PBAT, so that the cost is reduced, and the mechanical property and the degradation rate are increased. Compared to comparative examples 6 and 7, a faster degradation rate is shown, with an increase in efficiency of at least 35%. The reason is that the addition of water-absorbing starch and lignin pretreatment increase phenolic hydroxyl groups and reduce the molecular weight and particle size of lignin, thereby significantly enhancing the degradation rate.
A small decrease in both mechanical properties and degradation rate was seen compared to comparative example 1, due to: in the same time and the same solvent, the increase of water increases the dissociation rate, thereby increasing the abundance of hydroxyl groups, reducing the reactivity and further reducing the interface acting force; the water absorption is also reduced. Compared with the comparative example 2, due to different proportions, the acidic liquid is too high, the esterification is excessive in subsequent reaction, and due to the reduction of the conjugated phenolic groups, the ultraviolet absorptivity of the esterified lignin is reduced, so that the esterified lignin is unstable when used for preparing plastics, and the mechanical property and the degradation speed are reduced. The data is also reduced compared to comparative example 3, since all of the acidic solvents, corresponding to acid hydrolysis of lignin, can cause dissociation, but the reactivity of dehydration and acylation is reduced, so that the carbon-carbon double bond and the acylated group are reduced, the reactivity is reduced, and the interfacial force is reduced. In addition, the acylation reaction promotes the re-coagulation among the nano lignin to form nano microspheres, the substance has high oxidation resistance and ultraviolet absorptivity, and the ultraviolet absorptivity can photocrosslink the polyester in the low plastic, so that the reduction of the enzymatic hydrolysis of the plastic is prevented.
Compared with the comparative example 4, the eutectic solvent is unstable and the reactivity is reduced due to the exchange of the reaction steps and the dropwise addition of sodium hydroxide, and meanwhile, the transesterification of adipate is difficult and the compatibility is reduced due to the steric hindrance of the polyethylene glycol diglycidyl ether. Reducing the mechanical properties. Compared to comparative example 5, it can be found that the mechanical properties drop rapidly without the addition of the lignin mixture, due to: many of these materials, including eutectic solvent plasticizers, reactive plasticizers, and sodium lactate as a byproduct, significantly enhance the cross-linking and interfacial effects to combine the high levels of water-absorbing and hydrophobic materials.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A preparation method of lignin modified PBAT biodegradable plastic is characterized by comprising the following steps: the method comprises the following steps:
s1: dispersing lignin in a deep eutectic solvent mixed solution for pretreatment, precipitating with hot water, and performing solid-liquid separation; respectively treating solid and liquid to obtain lignin A and eutectic waste liquid;
s2: dispersing lignin A into the eutectic waste liquid again, adding lipase and adipic acid, and reacting; reducing the temperature, adding polyethylene glycol diglycidyl ether solution, stirring uniformly, dropwise adding sodium hydroxide aqueous solution, reacting, and freeze-drying to obtain a lignin mixture;
s3: sequentially adding the dried PBAT, the lignin mixture and the corn starch into a high-speed mixer for homogenization; and (3) kneading in a kneading machine, granulating, and performing injection molding to obtain the lignin modified PBAT biodegradable plastic.
2. The preparation method of the lignin-modified PBAT biodegradable plastic according to claim 1, characterized in that: the lignin is prepared from grape seeds by an enzymolysis method.
3. The preparation method of the lignin-modified PBAT biodegradable plastic according to claim 1, characterized in that: the deep eutectic solvent mixed solution is a mixed solution of a deep eutectic solvent and deionized water; the deep eutectic solvent is choline chloride and lactic acid in a mass ratio of 1: 1-2: 1, and the addition amount of the deionized water is 5-10% of the mass of the lactic acid.
4. The preparation method of the lignin-modified PBAT biodegradable plastic according to claim 1, characterized in that: the raw materials of the lignin-modified PBAT biodegradable plastic comprise, by weight, 70-85 parts of PBAT, 25-30 parts of corn starch, 26-40 parts of lignin, 2-4 parts of adipic acid and 6-10 parts of polyethylene glycol diglycidyl ether.
5. The preparation method of the lignin-modified PBAT biodegradable plastic according to claim 1, characterized in that: in the step S1, the mass ratio of the lignin to the deep eutectic solvent mixed liquid is 0.5-1: 2-5; in step S2, the ratio of lignin A to the eutectic waste liquid is 1: 0.5-0.8.
6. The preparation method of the lignin-modified PBAT biodegradable plastic according to claim 1, characterized in that: the specific process in step S1 is: dispersing lignin in a deep eutectic solvent mixed solution, and pretreating for 5-8 hours at the temperature of 60-140 ℃; injecting the reaction solution into hot water, stirring and precipitating, and carrying out solid-liquid separation; and drying the solid, and concentrating the liquid to obtain lignin A and eutectic waste liquid.
7. The preparation method of the lignin-modified PBAT biodegradable plastic according to claim 1, characterized in that: the specific process in step S2 is: dispersing the lignin A into the eutectic waste liquid again, setting the temperature to be 38-60 ℃, the stirring speed to be 150-250 rmp, adding lipase and adipic acid, and reacting for 1-2 hours; reducing the temperature to 30-35 ℃, adding a polyethylene glycol diglycidyl ether solution, uniformly stirring, setting the stirring speed to 300-400 rmp, dropwise adding a sodium hydroxide aqueous solution, reacting for 1-2 hours, and freeze-drying to obtain a lignin mixture.
8. The preparation method of the lignin-modified PBAT biodegradable plastic according to claim 7, characterized in that: the solvent of the polyethylene glycol diglycidyl ether solution is ethyl acetate.
9. The preparation method of the lignin-modified PBAT biodegradable plastic according to claim 1, characterized in that: in the step S3, the homogenizing temperature is 100-120 ℃; the kneading temperature is 140-180 ℃.
10. The lignin-modified PBAT biodegradable plastic prepared by the preparation method of the lignin-modified PBAT biodegradable plastic according to any one of claims 1 to 9.
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| CN114474449A (en) * | 2022-03-31 | 2022-05-13 | 北京林业大学 | Lignin/PBAT composite film material and preparation method and application thereof |
| CN114474449B (en) * | 2022-03-31 | 2022-09-13 | 北京林业大学 | Lignin/PBAT composite film material and preparation method and application thereof |
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