A biodegradable PBAT / bamboo charcoal masterbatch and its preparation method

Abstract

The present invention relates to a biodegradable PBAT / bamboo charcoal masterbatch, which comprises the following raw materials in parts by mass: 100 parts of poly(butylene adipate-co-terephthalate) (PBAT), 20-30 parts of poly(butylene succinate), 10-30 parts of modified bamboo charcoal powder, and 0.2-0.4 part of chain extender; the modified bamboo charcoal powder is obtained by subjecting bamboo charcoal powder to persulfate treatment, microwave-assisted reaction, and grafting agent modification in sequence, and the grafting agent comprises polybasic acid and epoxide compound. By grafting and modifying the bamboo charcoal powder, the present invention significantly improves the interfacial compatibility and matrix dispersibility with the PBAT substrate, and improves the mechanical properties of the composite material. The modifier with a specific proportion compounding improves the resistance to damp heat aging of the masterbatch composite material.

Description

Technical Field

[0001] The present invention belongs to the technical field of biodegradable plastics, and particularly relates to a biodegradable PBAT / bamboo charcoal masterbatch and a preparation method thereof. Background Art

[0002] Plastic products have been widely used in many fields such as packaging, construction, agriculture, automotive, and medical due to their light weight, durability, low cost, etc. However, traditional plastic products do not have the ability to degrade, so the large-scale production and use of plastic products have brought environmental pollution problems. Non-degradable plastics accumulate in the natural environment, causing long-term impacts on soil, water sources, wild animals and plants, and human health. Biodegradable plastic products refer to plastics whose various properties can meet the use requirements, whose properties do not change during the storage period, and which can be degraded into harmless substances that can be absorbed by nature under natural conditions after being discarded.

[0003] Poly(butylene adipate-co-terephthalate) (PBAT) is a completely biodegradable aromatic copolymer, and its mechanical properties are comparable to those of low-density polyethylene (LDPE). It has good toughness, ductility, film-forming properties, high impact strength, good melt processing properties, etc., and can be widely used in packaging materials. However, PBAT has defects such as low strength, poor creep resistance, low modulus, and high cost, which limit its application. Adding natural fillers is an effective way to improve the modulus of PBAT, improve its creep resistance, and reduce its cost. Bamboo charcoal is derived from the residues of low-cost bamboo harvesting and processing, has a carbon skeleton with high strength, is hard in texture, and can generate a rich multi-level pore structure through the control of the carbonization process. Given the advantages of the unique pore structure, surface hydrophobicity, and low cost of bamboo charcoal, the potential of bamboo charcoal as a powder filler to be compounded with biodegradable polymer materials is huge. Such composites can reduce costs, and by increasing the filling amount of inorganic powder in the material, the modulus, flame retardancy, and antistatic properties of the composite material can be significantly improved. At present, for the composite material of bamboo charcoal and PBAT, there is poor compatibility and insufficient matrix dispersion. As a result, the addition of bamboo charcoal has led to a serious decline in the mechanical properties of the composite material.

[0004] Patent CN113773626A discloses an environmentally friendly degradable masterbatch. Since less bamboo charcoal powder is added, it cannot effectively reduce costs and needs to be combined with modified corn starch, and the preparation process is relatively complex. In addition, since the carbonization temperature of the added bamboo charcoal is not controlled, the light shielding effect of the composite material prepared when used as a black masterbatch cannot be guaranteed. CN119081440A discloses a bamboo-based degradable material, which is composed of the following components by weight: 35-45 parts of bamboo powder, 20-25 parts of polylactic acid, 20-25 parts of PBAT, 5-10 parts of compatibilizer, and 5-10 parts of PBS. The compatibilizer is a maleic anhydride grafted compatibilizer. CN117624853A discloses a polylactic acid-based biodegradable composite material modified with bamboo powder, including polylactic acid, PBAT resin, modified bamboo powder, modified reinforcing filler, antioxidant, lubricant, and plasticizer; the modified bamboo powder is obtained by sequentially coating and modifying bamboo powder with polydopamine and grafting with maleic anhydride; the modified reinforcing filler is obtained by surface modification of calcium carbonate powder with coconut oil and stearic acid. Patent CN 101818414 A uses an aluminate coupling agent to modify bamboo charcoal to increase its compatibility with polypropylene, and uses liquid paraffin and zinc stearate as dispersants to promote the dispersion of bamboo charcoal. The modification effect of the coupling agent on low-density bamboo charcoal is limited and cannot effectively promote the formation of an effective interfacial layer between bamboo charcoal and the matrix resin. Traditional dispersants have poor plasticizing and dispersing effects at high bamboo charcoal contents and cannot effectively avoid the agglomeration and dispersion of bamboo charcoal. Therefore, the performance of the composite material obtained is low. Moreover, the content of bamboo charcoal powder used in this patent is low, and it cannot be shown that it is still effective at high bamboo charcoal powder contents. Summary of the Invention

[0005] In order to solve the defects in the prior art that the compatibility between PBAT materials and bamboo charcoal-based fillers is poor, the dispersion effect is poor, resulting in a low addition amount of bamboo charcoal fillers and poor mechanical properties of the composite material. The present invention uses a microwave-assisted heating method to modify bamboo charcoal in combination with a strong oxidant to increase the number of acidic oxygen-containing functional groups such as carboxyl groups on the surface, and then adds a polybasic acid as a compatibilizer to graft the bamboo charcoal to obtain grafted bamboo charcoal, so that an interpenetrating interfacial layer can be formed between the bamboo charcoal surface and PBAT, and an interlocking structure is formed between the two, improving the compatibility and dispersibility between bamboo charcoal and PBAT, thereby improving the mechanical properties of the bamboo charcoal / PBAT masterbatch and reducing costs.

[0006] Specifically, the present invention provides the following technical solutions to solve the above technical problems:

[0007] A biodegradable PBAT / bamboo charcoal masterbatch, comprising the following raw materials in parts by mass: 100 parts of poly(butylene adipate-co-terephthalate) (PBAT), 20-30 parts of poly(butylene succinate), 10-30 parts of modified bamboo charcoal powder, and 0.2-0.4 part of chain extender; the modified bamboo charcoal powder is obtained by subjecting bamboo charcoal powder to sulfate treatment, microwave-assisted reaction, and grafting agent modification in sequence, and the grafting agent comprises a polybasic acid and an epoxide compound.

[0008] Further, the poly(butylene adipate-co-terephthalate) has a weight-average molecular weight of 200,000-400,000; the poly(butylene succinate) has a molecular weight of 200,000-300,000; the chain extender is selected from one or more of 2,4-toluene diisocyanate, pyromellitic dianhydride, ethylene-glycidyl methacrylate copolymer, styrene-glycidyl methacrylate copolymer, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane. The persulfate is selected from at least one of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0009] Further, the polybasic acid is selected from at least one of tannic acid, itaconic acid, and succinic acid; the epoxide compound is selected from at least one of glycidyl acrylate, glycidyl methacrylate, styrene-glycidyl methacrylate copolymer, and methyl methacrylate-glycidyl methacrylate copolymer.

[0010] Further, the grafting agent is a compound of tannic acid, itaconic acid, and / or succinic acid, and an epoxide compound in a mass ratio of 3-5:3-5:1-2. The above compounded grafting agent can not only improve the mechanical properties of the composite material, but also significantly improve the high temperature and high humidity resistance of the composite material, further broadening the application range of such composite biodegradable materials. It should be noted that the dosage ratio of the compounded grafting agent should be controlled reasonably, otherwise it may have an adverse effect on the mechanical properties and / or biodegradability.

[0011] Further, the bamboo charcoal powder is obtained by carbonizing a low-density bamboo species, and the density of the low-density bamboo species is 0.33-0.5 g / cm 3 , such as Phyllostachys vivax f. aureocaulis (0.41 g / cm 3 ), Phyllostachys elegans (0.33 g / cm 3 ), Phyllostachys nigra var. henonis (0.43 g / cm 3). The carbonization process is well-known in the art. The low-density bamboo species material is cut into bamboo slices with a length of 1 - 5 cm, and first pre-oxidized at 300 - 400 °C (air flow rate 0.05 - 0.1 L / min) for 0.5 - 1 h. After pre-oxidation, the protective nitrogen gas flow is switched on, with a flow rate of 0.2 - 0.5 L / min, and the heating rate is 5 - 20 °C / min. The temperature is raised to 800 - 1100 °C for carbonization, and the carbonization time is 1 - 2 h. After carbonization, it is ground to 200 - 400 mesh, and after the grinding is completed, it is further ultra-finely ground to 1000 - 2000 mesh with a jet mill to obtain bamboo charcoal powder. The density of the obtained bamboo charcoal powder is 0.5 - 0.7 g / cm 3 , and the specific surface area is 500 - 700 m² / g.

[0012] The bamboo charcoal powder used in the present invention is a low-density carbon powder material with a density of 0.5 - 0.7 g / cm 3 , which is much lower than that of traditional petroleum-based carbon powder (1.5 - 1.85 g / cm 3 ). The low-density carbon powder can reduce the overall mass of the material while maintaining the same volume filling rate, improve the filling efficiency, and can effectively construct a conductive percolation network. The increase in specific surface area also provides more reactive sites. However, the low-density carbon powder material also brings some challenges. Compared with high-density carbon powder, it is more difficult to disperse and more prone to agglomeration, and the compatibility problem with the PBAT matrix material is also more difficult to solve. The present invention solves the above problems by modifying the bamboo charcoal powder.

[0013] Furthermore, the modified bamboo charcoal powder is prepared by a preparation method including the following steps:

[0014] (S1) The bamboo charcoal powder is impregnated in an aqueous solution of persulfate with a concentration of 0.5 - 1.0 mol / L and a mass multiple of 4 - 10 for 5 - 20 h. After that, the mixture is ultrasonically treated for 1 - 2 h to obtain a mixed solution;

[0015] (S2) The mixed solution is reacted under microwave conditions for 10 - 20 min, filtered, and the solid phase is washed and dried to obtain surface-treated bamboo charcoal powder;

[0016] (S3) The surface-treated bamboo charcoal powder is put into a grafting agent solution and reacted at 60 - 80 °C to obtain modified bamboo charcoal powder.

[0017] Furthermore, in step (S1), the persulfate is selected from at least one of sodium persulfate, potassium persulfate, and ammonium persulfate; the conditions of the ultrasonic treatment are a power of 100 - 200 W and a frequency of 60 - 180 kHz.

[0018] Further, in step (S2), the washing is carried out by water washing until the washing liquid is neutral; the power under microwave conditions is 600 - 1000 W, such as 800 W or 900 W. The purpose of the microwave treatment reaction is to break up the microporous structure of the bamboo charcoal, further reduce the dispersion particle size, increase the porosity of the bamboo charcoal, expand the pore size, and the structural change helps to increase the specific surface area and adsorption capacity of the bamboo charcoal, thereby enhancing its reaction to the oxidant. At the same time, microwave-assisted heating provides more uniform energy supply, and the energy is transferred to the interior of the bamboo charcoal more quickly, causing the bamboo charcoal particles to heat up rapidly. This helps to accelerate the reaction rate and efficiency between the oxidant and the surface of the bamboo charcoal, increase the reaction process, and thus obtain more acidic functional groups, that is, the reaction sites for subsequent graft modification agents.

[0019] Further, in step (S3), the grafting agent solution is obtained by dissolving the grafting agent in an organic solvent, and the organic solvent is selected from at least one of ethanol, ethyl acetate, dichloromethane, and chloroform. The concentration of the grafting agent solution is 20 - 30 wt%. The mass ratio of the surface-treated bamboo charcoal powder to the grafting agent solution is 1:6 - 10; the reaction time is 1 - 2 h. After the reaction, filtration, washing, and drying are carried out to obtain the modified bamboo charcoal powder.

[0020] The modified bamboo charcoal powder of the present invention is obtained by successively performing oxidation, microwave reaction, and graft modification on low-density bamboo charcoal powder. It makes the surface of the modified bamboo charcoal powder have abundant functional groups, significantly improves the compatibility with PBAT materials, and enhances the mechanical properties of the composite material. Using a mixture of two polyacids and an epoxide as the grafting agent can significantly improve the mechanical properties of the material, especially improve the resistance to heat and humidity of the material.

[0021] The present invention also provides a preparation method for biodegradable PBAT / bamboo charcoal masterbatch, including the following steps: Poly(butylene adipate-co-terephthalate) (PBAT), poly(butylene succinate), bamboo charcoal powder, and a chain extender are mixed evenly in a mixer to obtain the biodegradable PBAT / bamboo charcoal masterbatch.

[0022] Further, the preparation method of the biodegradable PBAT / bamboo charcoal masterbatch includes the following steps:

[0023] Poly(butylene adipate-co-terephthalate) (PBAT) and poly(butylene succinate) are added to a mixer and mixed at 150 - 180 °C and a rotation speed of 60 - 100 rpm for 1 - 5 min. Then the modified bamboo charcoal powder is added, and mixing is continued for 1 - 5 min. Finally, the chain extender is added and mixed for 3 - 10 min. After the mixing is completed, it is cooled to room temperature to obtain the product biodegradable PBAT / bamboo charcoal masterbatch.

[0024] Compared with the prior art, the modified bamboo charcoal powder prepared by the present invention through specific raw materials and methods has significantly improved interfacial compatibility and matrix dispersibility with the PBAT substrate, thereby enhancing the mechanical properties of the composite material. In addition, through the modifier compounded in a specific ratio, the heat and humidity aging resistance of the composite material is improved. After the obtained composite material is placed in a high temperature and high humidity environment of double 85 for 30 days, the loss of mechanical properties is very low. Description of the Drawings

[0025] Figure 1 is a polarized light microscope picture of the composite material obtained in Example 3;

[0026] Figure 2 is a scanning electron microscope picture of the composite material obtained in Example 3. Detailed Embodiments

[0027] The technical solutions of the present invention will be further explained and illustrated below with specific examples.

[0028] The bamboo charcoal powder used in the present invention is made from Yachu bamboo (0.33 g / cm 3 ) cut into bamboo slices of 1 - 2 cm, baked until the water content is lower than 5%. First, it is pre-oxidized at 400 °C for 1 h with an air flow rate of 0.1 L / min, and then switched to nitrogen with a flow rate of 0.4 L / min. The temperature is raised to 1000 °C at a heating rate of 15 °C / min and held for 2 h to complete carbonization. After carbonization, the carbon material is crushed to 400 meshes by a Raymond mill and then ground to 1500 meshes by a jet mill to obtain bamboo charcoal powder with a density of 0.52 g / cm 3 .

[0029] Poly(butylene adipate-co-terephthalate) (PBAT) has a weight average molecular weight of about 260,000 and a melt index of 3.1 g / 10 min.

[0030] Poly(butylene succinate) has a weight average molecular weight of about 240,000 and a melt index of 6.8 g / 10 min.

[0031] Preparation Example 1

[0032] (S1) 100 parts by mass of bamboo charcoal powder is impregnated in 500 parts by mass of 0.9 mol / L potassium persulfate solution. After stirring evenly, it is soaked at room temperature for 10 h, and then the mixture is placed in an ultrasonic cleaner and ultrasonically treated for 2 h at an ultrasonic frequency of 100 kHz and an ultrasonic power of 120 W to obtain a mixed solution;

[0033] (S2) The mixed solution is placed in a quartz glass reactor and then put into a microwave oven. It is reacted for 10 minutes at a microwave power of 800 W, filtered, and the solid phase is washed with distilled water until neutral, then placed in a drying oven and dried to constant weight at 120 °C to obtain surface-treated bamboo charcoal powder;

[0034] (S3) Add the grafting agent to dichloromethane and stir vigorously for 5 minutes to prepare a 20 wt% grafting agent solution. The grafting agent is a compound of tannic acid, itaconic acid, and glycidyl methacrylate in a mass ratio of 3:3:1. Put the surface-treated bamboo charcoal powder obtained in step S2 into the grafting agent solution and stir. The mass ratio of the surface-treated bamboo charcoal to the grafting agent solution is 1:6. Stir and react in a water bath at 80 °C until the dichloromethane completely evaporates. First, wash with alcohol, then wash with water, and dry in an oven at 100 °C to obtain modified bamboo charcoal powder.

[0035] Preparation Example 2

[0036] Other conditions are the same as those in Preparation Example 1, except that in step (S3), the grafting agent is a compound of tannic acid, succinic acid, and glycidyl methacrylate in a mass ratio of 5:5:2.

[0037] Preparation Example 3

[0038] Other conditions are the same as those in Preparation Example 1, except that in step (S3), the grafting agent is a compound of tannic acid and succinic acid in a mass ratio of 1:1.

[0039] Preparation Example 4

[0040] Other conditions are the same as those in Preparation Example 1, except that in step (S3), the grafting agent is glycidyl methacrylate.

[0041] Preparation Example 5

[0042] Other conditions are the same as those in Preparation Example 1, except that in step (S3), the grafting agent is a compound of succinic acid and glycidyl methacrylate in a mass ratio of 3:1.

[0043] Preparation Example 6

[0044] Other conditions are the same as those in Preparation Example 1, except that in step (S3), the grafting agent is a compound of tannic acid and glycidyl methacrylate in a mass ratio of 3:1.

[0045] Comparative Preparation Example 1

[0046] (S1) Immerse 100 parts by mass of bamboo charcoal powder in 500 parts by mass of 0.9 mol / L potassium persulfate solution. After stirring evenly, soak at room temperature for 10 h. Then, place the mixture in an ultrasonic washer and ultrasonicate at an ultrasonic frequency of 100 kHz and an ultrasonic power of 120 W for 2 h. Filter the obtained bamboo charcoal powder, wash it, and dry it to obtain oxidized bamboo charcoal powder;

[0047] (S2) adding a grafting agent to dichloromethane and stirring vigorously for 5 minutes to prepare a 20wt% grafting agent solution, wherein the grafting agent is a compound of tannic acid, itaconic acid, and glycidyl methacrylate in a mass ratio of 3:3:1, and the oxidized bamboo charcoal powder obtained in step S1 is placed in the grafting agent solution and stirred, and the weight ratio of the surface-treated bamboo charcoal to the grafting agent solution is 1:6, and the reaction is stirred in a water bath at 80°C until the dichloromethane is completely volatilized, first washed with alcohol, then washed with water, and dried in an oven at 100°C to obtain modified bamboo charcoal powder. That is, compared with Preparation 1, the microwave reaction of step (S2) is not performed.

[0048] Comparative Preparation Example 2

[0049] The other conditions are the same as those in Preparation Example 1, except that in step (S3), the grafting agent is maleic anhydride grafted polylactic acid (PLA-g-St / MAH, purchased from Xi'an Qiyue Biology).

[0050] Example 1

[0051] 100 parts by weight of butylene terephthalate-adipate (PBAT) and 30 parts by weight of polybutylene succinate were placed in an internal mixer at 150° C. and a mixing speed of 60 rpm for 1 min, and then 10 parts by weight of the modified bamboo charcoal powder prepared in Preparation Example 1 were added, mixed at 60 rpm for 2 minutes, and then 0.2 parts by weight of a chain extender 2,4-toluene diisocyanate was added, and mixing was continued at 60 rpm for 4 min. After mixing, the blend was cut into small pieces and directly cooled in air at room temperature to obtain the bamboo charcoal / PBAT composite material provided by the present invention.

[0052] Example 2

[0053] The other conditions were the same as those in Example 3, except that the amount of the modified bamboo charcoal powder prepared in Preparation Example 1 was 20 parts by weight.

[0054] Example 3

[0055] The other conditions were the same as those in Example 3, except that the amount of modified bamboo charcoal powder prepared in Preparation Example 1 was 30 parts by weight.

[0056] Figure 1 This is a polarizing microscope picture of the composite material obtained in Example 3, which can show from the side that the bamboo charcoal is evenly dispersed in the matrix. Figure 2 This is a scanning electron microscope image of the composite material obtained in Example 3. The boundary between bamboo charcoal and PBAT is not obvious, indicating that a mutually penetrating interface layer is formed and the interface compatibility is very good.

[0057] Example 4

[0058] The other conditions were the same as those in Example 3, except that the modified bamboo charcoal powder prepared in Preparation Example 1 was replaced by the modified bamboo charcoal powder prepared in Preparation Example 2.

[0059] Example 5

[0060] Other conditions are the same as those in Example 3, except that the modified bamboo charcoal powder obtained in Preparation Example 1 is replaced by that obtained in Preparation Example 3.

[0061] Example 6

[0062] Other conditions are the same as those in Example 3, except that the modified bamboo charcoal powder obtained in Preparation Example 1 is replaced by that obtained in Preparation Example 4.

[0063] Example 7

[0064] Other conditions are the same as those in Example 3, except that the modified bamboo charcoal powder obtained in Preparation Example 1 is replaced by that obtained in Preparation Example 5.

[0065] Example 8

[0066] Other conditions are the same as those in Example 3, except that the modified bamboo charcoal powder obtained in Preparation Example 1 is replaced by that obtained in Preparation Example 6.

[0067] Comparative Example 1

[0068] Other conditions are the same as those in Example 3, except that the modified bamboo charcoal powder obtained in Preparation Example 1 is replaced by the modified bamboo charcoal powder obtained in Comparative Preparation Example 1 with the same mass (i.e., 30 parts by mass).

[0069] Comparative Example 2

[0070] Other conditions are the same as those in Example 3, except that the modified bamboo charcoal powder obtained in Preparation Example 1 is replaced by the modified bamboo charcoal powder obtained in Comparative Preparation Example 2 with the same mass (i.e., 30 parts by mass).

[0071] Comparative Example 3

[0072] Other conditions are the same as those in Example 3, except that the modified bamboo charcoal powder obtained in Preparation Example 1 is replaced by untreated bamboo charcoal powder with the same mass (i.e., 30 parts by mass).

[0073] Application Example

[0074] The following performance tests were carried out on the composite materials obtained in the above examples and comparative examples, and the results are shown in Table 1 below.

[0075] 1. Press the composite material into a sheet on a flat vulcanizing machine at 150 °C under a pressure of 10 MPa, and then quickly place it in a cold press and keep it under a pressure of 2 MPa to cool to room temperature to obtain a blended material sheet for testing. Cut the sheet into a dumbbell shape and test the tensile strength and elongation at break of the blend according to GB / T 1040.1-2018.

[0076] 2. Limiting Oxygen Index (LOI): The obtained blend was pressed into a sheet on a flat vulcanizer at 150 °C under a pressure of 10 MPa, and then quickly placed in a cold press and kept under a pressure of 2 MPa until cooled to room temperature to obtain a blend material sheet for testing. The sheet was cut into 150 mm × 10 mm × 4 mm, and the limiting oxygen index of the blend was tested according to Standard GB / T 2406-2008.

[0077] 3. High temperature and high humidity resistance performance: After the composite material was placed at 85 °C and 85% RH for 30 days, the tensile strength and elongation at break were retested, and the tensile strength retention rate and elongation at break retention rate were calculated.

[0078] 4. Surface resistivity: The composite material was molded by pressing at 180 °C and 10 MPa for 10 min, and then kept under pressure and cooled to obtain a sheet with a specification of 120 mm × 100 mm × 2 mm. The surface resistivity of the composite material was measured at room temperature using a high resistance meter, and 5 groups of parallel tests were conducted. The results were the average of the 5 groups of data.

[0079] Table 1 Performance test of bamboo charcoal / PBAT composite materials

[0080] 。

Claims

1. A biodegradable PBAT / bamboo charcoal masterbatch, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of polybutylene terephthalate-adipate (PBAT), 20-30 parts of polybutylene succinate, 10-30 parts of modified bamboo charcoal powder, and 0.2-0.4 parts of a chain extender; the modified bamboo charcoal powder is obtained by sequentially subjecting the bamboo charcoal powder to persulfate treatment, microwave-assisted reaction, and grafting agent modification; the chain extender is 2, 4-toluene diisocyanate; the grafting agent is tannic acid, itaconic acid or succinic acid, and an epoxy compound in a mass ratio of 3-5:3-5:1-2; the epoxy compound is selected from at least one of glycidyl acrylate, glycidyl methacrylate, styrene-glycidyl methacrylate copolymer, and methyl methacrylate-glycidyl methacrylate copolymer.

2. The biodegradable PBAT / bamboo charcoal masterbatch according to claim 1, characterized in that: The weight average molecular weight of the polybutylene terephthalate-adipate is 200,000-400,000; the molecular weight of the polybutylene succinate is 200,000-300,000; and the persulfate is selected from at least one of sodium persulfate, potassium persulfate and ammonium persulfate.

3. The biodegradable PBAT / bamboo charcoal masterbatch according to claim 1, characterized in that: The bamboo charcoal powder is obtained by carbonizing low-density bamboo species, and the density of the low-density bamboo species is 0.33-0.5 g / cm 3 The density of the bamboo charcoal powder obtained after carbonization is 0.5-0.7g / cm 3 , with a specific surface area of ​​500-700 m² / g.

4. The biodegradable PBAT / bamboo charcoal masterbatch according to claim 1, characterized in that: The modified bamboo charcoal powder is prepared by a preparation method comprising the following steps: (S1) immersing the bamboo charcoal powder in a 0.5-1.0 mol / L strong oxidant aqueous solution at a concentration of 4-10 times by weight for 5-20 h, and then subjecting the mixture to ultrasonic treatment for 1-2 h to obtain a mixed solution; (S2) reacting the mixed solution under microwave conditions for 10-20 min, filtering, washing the solid phase, and drying to obtain surface-treated bamboo charcoal powder; (S3) The surface-treated bamboo charcoal powder is placed in a grafting agent solution and reacted at 60-80° C. to obtain modified bamboo charcoal powder.

5. The biodegradable PBAT / bamboo charcoal masterbatch according to claim 4, characterized in that: In step (S1), the ultrasonic treatment is performed at a power of 100-200 W and a frequency of 60-180 kHz; and / or In step (S2), the microwave condition power is 600-1000W; washing is washing with water until the washing liquid is neutral.

6. The biodegradable PBAT / bamboo charcoal masterbatch according to claim 4, characterized in that: In step (S3), the grafting agent solution is obtained by dissolving the grafting agent in an organic solvent, the organic solvent is selected from at least one of ethanol, ethyl acetate, dichloromethane, and chloroform, and the concentration of the grafting agent solution is 20-30wt%; the mass ratio of the surface-treated bamboo charcoal powder to the grafting agent solution is 1:6-10; the reaction time is 1-2h, and after the reaction is completed, filtering, washing, and drying are performed to obtain modified bamboo charcoal powder.

7. The method for preparing the biodegradable PBAT / bamboo charcoal masterbatch according to any one of claims 1 to 6, characterized in that: The following steps are involved: Polybutylene terephthalate-adipate, polybutylene succinate, modified bamboo charcoal powder and chain extender are uniformly mixed in an internal mixer to obtain biodegradable PBAT / bamboo charcoal masterbatch.

8. The preparation method according to claim 7, characterized in that: The following steps are involved: Polybutylene terephthalate-adipate and polybutylene succinate are added to an internal mixer, mixed for 1-5 minutes at 150-180°C and 60-100 rpm, modified bamboo charcoal powder is added, and mixing is continued for 1-5 minutes. Finally, a chain extender is added and mixing is continued for 3-10 minutes. After mixing, the mixture is cooled to room temperature to obtain a biodegradable PBAT / bamboo charcoal masterbatch.

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