A closed-loop recycling caprolactone prepared PBAT / TPS-RC fully biodegradable material with double shape memory performance

Abstract

The present application belongs to the technical field of fully biodegradable materials, and discloses a closed-loop recycled caprolactone preparation PBAT / TPS-RC fully biodegradable material with double shape memory performance. The present application utilizes thermal cracking efficient closed-loop recycled caprolactone monomer, generates polycaprolactone grafted starch copolymer through in-situ ring-opening polymerization, and is extruded into TPS-RC with excellent shape memory performance. When TPS-RC is blended with PBAT through double screw extrusion and blown into a film, TPS-RC is uniformly dispersed in the PBAT matrix at a micro-nano scale, and PBAT / TPS-RC exhibits excellent mechanical properties. Interestingly, due to the presence of a plasticizer with strong microwave absorption, PBAT / TPS-RC can realize double thermal and microwave driven shape memory characteristics with a shape recovery rate of up to 97% and 100% respectively in 10-40s through heating or microwave heating.

Description

Technical Field

[0001] This invention belongs to the field of fully biodegradable materials, and specifically relates to a PBAT / TPS-RC fully biodegradable material with dual shape memory properties prepared by closed-ring recovery of caprolactone. Background Technology

[0002] Currently, the environmental threat posed by petroleum-based plastics has prompted researchers to conduct extensive research and pay attention to fully biodegradable materials. Among these methods, blending expensive polybutylene terephthalate (PBAT) with inexpensive thermoplastic starch (TPS) is an effective way to reduce costs, obtain excellent overall performance, and replace polyethylene (PE) plastic films.

[0003] Domestic and international research on PBAT / TPS films has primarily focused on improving their mechanical, barrier, and thermal properties, aiming to prepare high-performance PBAT / TPS biodegradable films to expand their application areas. However, researchers have overlooked the fact that amorphous PBAT / TPS films, despite their excellent flexibility, still suffer from high creep. This is the direct cause of the biodegradable material's tendency to deform during daily use, eventually rendering it unusable and turning it into disposable biodegradable waste. Although PBAT / TPS films possess biodegradable properties, their final degradation forms are primarily carbon dioxide and water, which does not fully align with the low-carbon concept.

[0004] Dong Yubing et al. (International Journal of Biological Macromolecules: Structure, Function and Interactions, 2023, 240) prepared a photocrosslinked PBAT / starch film with good thermally driven shape memory properties via a one-step reactive extrusion method. At a PBAT / starch ratio of 1:1, the film achieved a recovery rate of 93.94%, but the tensile strength and elongation at break were only 9.9 MPa and 400%, respectively. Chinese patent CN202310958933.0, through melt extrusion of CaCO3 powder and PBAT particles, with the assistance of epoxy chain extender ADR and compatibilizer SMA-2005, prepared a CaCO3 / PBAT film with good shape memory and thermal shrinkage properties, achieving a recovery rate of over 80% at 120℃. Research on other bio-based shape memory composite materials is also gradually attracting attention. Chinese patent CN201510020770.7 describes the preparation of polylactic acid-based shape memory composite materials with excellent mechanical and shape memory properties by mixing polylactic acid (PLA) with different thermoplastic elastomers. However, most of the thermoplastic elastomers that play a crucial role in the material's biodegradability are not biodegradable, affecting the overall degradation performance of the material. Chinese patent CN201711348973.4 describes the preparation of a biodegradable material with shape memory properties by purifying malic acid under negative pressure at 110°C for 45 hours, followed by a 9-hour negative pressure reaction with glycerol. The optimal tensile strength is 10000 kPa. However, this patent uses a chemical synthesis method, which includes purification processes, resulting in a long and complex preparation cycle.

[0005] Therefore, it is of great significance to find a simple and easy way to enable PBAT / TPS fully biodegradable materials with excellent mechanical properties to fully realize their value and improve their reusability through multiple shape memory characteristics. Summary of the Invention

[0006] In order to overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a TPS-RC material with shape memory properties.

[0007] This invention utilizes caprolactone monomers that are efficiently recovered through thermal decomposition and closed-loop polymerization to generate polycaprolactone-grafted starch copolymers via in-situ ring-opening polymerization, and then obtains TPS-RC with excellent shape memory properties through extrusion molding.

[0008] Another objective of this invention is to provide a PBAT / TPS-RC composite material with dual shape memory based on the above-mentioned TPS-RC.

[0009] This invention utilizes TPS-RC, which has excellent shape memory properties, to endow PBAT with excellent thermally driven shape memory properties and microwave-driven shape memory properties.

[0010] Another objective of this invention is to provide a method for preparing the above-mentioned PBAT / TPS-RC composite material with dual shape memory.

[0011] Another object of the present invention is to provide the application of the above-mentioned PBAT / TPS-RC composite material with dual shape memory in fully biodegradable materials.

[0012] The objective of this invention is achieved through the following solution:

[0013] A TPS-RC material with shape memory properties, comprising 70-85 parts by weight of polycaprolactone-grafted starch and 15-30 parts by weight of polar plasticizer;

[0014] The raw materials for polycaprolactone-grafted starch include 70-85 parts by weight of starch, 700-850 parts by weight of water, 10-100% by weight of caprolactone by starch mass, and 0.1-1 mol% by weight of caprolactone monomer as catalyst.

[0015] The starch is at least one of corn starch, tapioca starch, and potato starch.

[0016] The caprolactone is a product of polycaprolactone (PCL) recovered through efficient closed-loop thermal decomposition, comprising 90-100 wt% caprolactone monomer, with the remainder being caprolactone dimer and caprolactone trimer.

[0017] The catalyst is at least one of stannous isooctanoate, cesium hydroxide monohydrate, HND580 solid acid catalyst, magnesium chloride hexahydrate, and stannous chloride.

[0018] The polar plasticizer is at least one of glycerol, ethylene glycol, pentaerythritol, sorbitol, urea, and formamide.

[0019] The preparation method of the above-mentioned TPS-RC material with shape memory properties includes the following steps:

[0020] (1) Add starch to water, gelatinize it, add caprolactone premix, add catalyst, and carry out in-situ ring-opening polymerization to obtain polycaprolactone grafted starch.

[0021] (2) Polycaprolactone-grafted starch is mixed with a polar plasticizer and blended to obtain TPS-RC material.

[0022] The gelatinization temperature in step (1) is 70-100℃; the time is 1-3h.

[0023] The premixing temperature in step (1) is 70-100℃; the time is 5-15h.

[0024] The in-situ ring-opening polymerization reaction in step (1) is carried out at a temperature of 100-130℃ for 5-15 hours.

[0025] After the reaction described in step (1), the product is washed twice with ethanol, dried, pulverized using a crusher, washed three times with dichloromethane, and dried to obtain polycaprolactone-grafted starch.

[0026] After mixing in step (2), let it stand for 8-16 hours.

[0027] The blending in step (2) is melt blending, including at least one of extrusion, internal mixing, injection molding, and open mixing.

[0028] The extruder used for blending in step (2) is a co-rotating parallel twin-screw extruder (L / D = 40:1); the parameters of the extruder are set as follows: the temperature range from the extruder feed port to the die head is 80-160℃, and the screw speed is 80-120r / min.

[0029] A PBAT / TPS-RC composite material with dual shape memory based on the above-mentioned TPS-RC comprises 50-70 parts by weight of PBAT, 30-50 parts by weight of TPS-RC material, and 0.5-3 parts by weight of coupling agent.

[0030] The coupling agent is at least one of KH550, KH570, DL-411, and LK-201.

[0031] The preparation method of the above-mentioned PBAT / TPS-RC composite material with dual shape memory includes the following steps: mixing TPS-RC material, PBAT and coupling agent, and obtaining PBAT / TPS-RC composite material by melt blending.

[0032] The melt blending is at least one of extrusion, internal mixing, injection molding, open milling, and blow molding.

[0033] The extruder for melt blending is a co-rotating parallel twin-screw extruder (L / D = 40:1); the parameters of the extruder are set as follows: the temperature from the feed port to the die head is 100-180℃, and the screw speed is 50-300 r / min.

[0034] The above-mentioned PBAT / TPS-RC composite material with dual shape memory is used in fully biodegradable materials.

[0035] The specific application involves preparing a thin film from PBAT / TPS-RC composite material using a blow molding machine.

[0036] The blow molding machine is a single-screw extrusion blow molding machine; the parameters are set as follows: film thickness 0.03-0.05mm, film blow-up ratio 0.5-2.5, extruder screw speed 70-100rpm, and temperature 140-150℃.

[0037] The mechanism of this invention is as follows:

[0038] This invention utilizes caprolactone monomers recovered through thermal decomposition to successfully graft onto starch molecular chains. Compared to pure starch, after a series of reactions including high temperature, stirring, and gelatinization, the molecular weight of polycaprolactone-grafted starch decreases, thus facilitating starch plasticization and improving the flowability of TPS-RC, significantly enhancing its dispersibility in PBAT. Furthermore, polycaprolactone not only provides the fixing force to ensure temporary shape stability but also guarantees the shrinkage force to restore the original permanent shape, giving TPS-RC excellent shape memory properties.

[0039] This invention uses polycaprolactone (PPT) as a switch, raising or lowering the temperature under external environmental stimuli to promote or restrict the movement of surrounding molecular chains. When TPS-RC is co-extruded and blended with PBAT via twin-screw extrusion and blown into film, TPS-RC is uniformly dispersed in the PBAT matrix at the micro-nano scale. Good compatibility endows PBAT / TPS-RC with excellent mechanical properties. Simultaneously, raising the temperature can activate excellent thermally driven shape memory properties in PBAT / TPS-RC. Notably, the polar plasticizer in the TPS-RC component also acts as a strong microwave absorber, rapidly converting microwave energy into heat energy, perfectly realizing the excellent microwave-driven shape memory properties of PBAT / TPS-RC. Ultimately, the PBAT / TPS-RC film material prepared by this invention can effectively eliminate creep and restore its original dimensions after use, achieving the goal of reusable PBAT / TPS-RC disposable plastic bags.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] (1) In terms of research significance, this invention is the first to break away from the problem of using biodegradable materials to replace petroleum-based plastics to alleviate environmental pressure. It novelly proposes to endow bio-based materials (such as PBAT / TPS materials with high creep and difficulty in recovering the initial size defects after stress) with certain shape memory properties, thereby solving the problem of materials being discarded due to deformation during use, extending the material life cycle, and realizing the purpose of maximizing the value of PBAT / TPS disposable plastic materials through repeated use. It has the advantages of reducing carbon emissions and improving resource utilization.

[0042] (2) This invention proposes for the first time to use the caprolactone monomer recovered by efficient closed-loop thermal decomposition to generate polycaprolactone-grafted starch copolymer through in-situ polymerization. The polycaprolactone grafted onto the starch chain not only provides the fixing force to ensure the stability of the temporary shape, but also ensures the shrinkage force to restore the original permanent shape, thus successfully realizing the excellent shape memory characteristics of TPS-RC.

[0043] (3) This invention maintains the fully biodegradable properties of the material while preparing a reusable PBAT / TPS-RC material with excellent dual shape memory properties by extruding and blending TPS-RC, which has good shape memory properties, with PBAT, which has high creep defects. When TPS-RC and PBAT are twin-screw extruded and blown into film, TPS-RC is dispersed in the PBAT matrix at the micro-nano scale, which reduces the cost of PBAT without losing its excellent mechanical properties (23.8 MPa, 1126%), and for the first time endows PBAT with excellent dual shape memory properties. PBAT / TPS-RC has excellent thermally driven shape memory, and the polar plasticizer in the TPS-RC component can also act as a strong microwave absorber, which is expected to quickly convert microwave energy into heat energy, thereby increasing the temperature of PBAT / TPS-RC and perfectly realizing the excellent microwave-driven shape memory properties of PBAT / TPS-RC. Specifically, under thermal driving for 20-40 seconds, the shape recovery rate of the PBAT / TPS-RC material reached 97%, and under microwave driving for 10-20 seconds, the shape recovery rate reached 100%. Ultimately, the PBAT / TPS-RC film material prepared by this invention can effectively eliminate creep after use, allowing the sample to return to its original dimensions, thus achieving the goal of reusing PBAT / TPS-RC disposable plastic bags. Attached Figure Description

[0044] Figure 1 The graph shows the "U"-shaped test results of the TPS obtained in Comparative Example 2 and the TPS-RC obtained in Examples 1-3.

[0045] Figure 2 The infrared spectrum and 1H NMR spectrum are of the corn starch in Comparative Example 2 and the polycaprolactone-grafted starch raw material in Example 3.

[0046] Figure 3 The image shows the "U"-shaped test results of the products obtained in Comparative Example 2 and Example 3.

[0047] Figure 4 The image shows the microwave test results of the products obtained in Comparative Examples 1-2, Example 3, and Example 5. Detailed Implementation

[0048] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0049] Unless otherwise specified, all reagents used in the examples are commercially available.

[0050] The corn starch (food grade) used in the following examples was purchased from Shandong Hengren Industry & Trade Co., Ltd.; glycerol (analytical grade) was purchased from Tianjin Damao Chemical Reagent Factory; polybutylene terephthalate (extrusion grade) was purchased from Xinjiang Western Water Saving Technology Co., Ltd.; PCL was purchased from Hunan Juren Chemical New Material Technology Co., Ltd.; M w 50000 g / mol.

[0051] Preparation of caprolactone:

[0052] In the vacuum distillation reaction system, PCL was stirred at 120°C for 2 hours to remove small molecule impurities from the system. Subsequently, 0.25 mol% (as a percentage of PCL) of stannous isooctanoate was added, and the reaction was carried out at 250°C and 0.08 MPa vacuum. The reaction product was collected by condensation, and after a period of time, the collection was stopped to obtain the recovered product caprolactone.

[0053] GC testing revealed that the recovered product contained 91.1 wt% caprolactone monomer, with the remainder being caprolactone dimer and caprolactone trimer.

[0054] In the following examples and comparative examples, 1 part by weight is 1 gram.

[0055] Example 1

[0056] Step 1: Disperse 300 parts by weight of dried corn starch in a reactor containing 3000 parts by weight of deionized water. After gelatinizing at 80°C for 2 hours by mechanical stirring, introduce 60 parts by weight of caprolactone for premixing for 10 hours. Finally, raise the temperature to 110°C and add 0.5 mol% (percentage of caprolactone monomer) of stannous isooctanoate to catalyze the reaction for 10 hours.

[0057] Step 2: Wash the product from Step 1 with a large amount of ethanol and allow it to settle twice. After the sediment is completely dried, grind it into powder, wash it three times with dichloromethane, and dry it for later use to obtain polycaprolactone-grafted starch raw material.

[0058] Step 3: Take 290 parts by weight of the raw material from Step 2 and mix it with 110 parts by weight of glycerin until homogeneous, and let it stand for 12 hours.

[0059] Step four: The mixture that has been allowed to stand in step three is extruded through a co-rotating twin-screw extruder. The temperature range from the extruder feed port to the die head is set to 90-160℃, and the screw speed is 100r / min. After cooling and granulation, TPS-3RC granules are obtained.

[0060] Step 5: After premixing 300 parts by weight of TPS-3RC granules, 700 parts by weight of PBAT and 20 parts by weight of KH570 from Step 4 evenly, the mixture is reactively extruded through a co-rotating twin-screw extruder. The temperature range from the extruder feed port to the die head is set to 110-170℃, and the screw speed is 100r / min. After cooling and granulation, PBAT / TPS-3RC blend granules are obtained.

[0061] Example 2

[0062] The difference from Example 1 is that: 150 parts by weight of caprolactone are introduced in step one; the product obtained in step four is TPS-10RC; and the product obtained in step five is PBAT / TPS-10RC.

[0063] Example 3

[0064] The difference from Example 1 is that: 300 parts by weight of caprolactone are introduced in step one; the product obtained in step four is TPS-17RC; and the product obtained in step five is PBAT / TPS-17RC.

[0065] Example 4

[0066] The difference from Example 3 is that: in step three, 310 parts by weight of the raw material in step two and 90 parts by weight of glycerol are mixed evenly; in step four, the product obtained is TPS-17RC'; and in step five, the product obtained is PBAT / TPS-17RC'.

[0067] Example 5

[0068] The difference from Example 3 is that: in step three, 330 parts by weight of the raw material from step two and 70 parts by weight of glycerol are mixed evenly; in step four, the product obtained is TPS-17RC”; and in step five, the product obtained is PBAT / TPS-17RC”.

[0069] Comparative Example 1

[0070] The difference from Example 1 is that steps one to four are omitted, and in step five, 1000 parts by weight of PBAT particles and 83 parts by weight of glycerol are premixed evenly to obtain PBAT as the product.

[0071] Comparative Example 2

[0072] The difference from Example 1 is that steps one and two are omitted, and in step three, 275 parts by weight of glycerol and 725 parts by weight of corn starch are mixed evenly; the product obtained in step four is TPS; and the product obtained in step five is PBAT / TPS.

[0073] Test Implementation Example:

[0074] 1. Structural characterization and grafting rate:

[0075] Figure 2 The infrared spectrum and 1H NMR spectrum of corn starch in Comparative Example 2 and polycaprolactone-grafted starch raw material in Example 3 are shown. The infrared spectrum at 1730 cm⁻¹ is also shown. -1 A distinct ester group peak appears, and it is located at 2800-2950 cm⁻¹. -1 The enhanced methylene peak and the obvious signal peaks of PCL at 1.3-2.3 ppm and 3.99 ppm in the 1H NMR spectrum indicate that polycaprolactone was successfully grafted into the starch molecular chain.

[0076] In addition, calculations showed that the grafting rates of the polycaprolactone-grafted starch raw materials in Examples 1-3 were 3.2%, 9.8%, and 16.6%, respectively, and were therefore represented as TPS-3RC, TPS-10RC, and TPS-17RC.

[0077] 2. Tensile property test:

[0078] The products obtained in Examples 1-3 and Comparative Examples 1-2 were blow-molded into films and subjected to tensile property tests (in accordance with GB / T1040-2006, the tensile rate was set to 500 mm / min). The test results are shown in Table 1.

[0079] Methods of blow molding for film formation:

[0080] The products obtained in Examples 1-3 and Comparative Examples 1-2 were blown into films with a thickness of 0.03-0.05 mm using a single-screw extrusion blown film machine. The film blow-up ratio was 1.5, the extruder screw speed was 80 rpm, and the temperature was 140-150℃.

[0081] Table 1 Tensile Properties

[0082]

[0083] 3. "U"-shaped test:

[0084] The TPS-RC obtained in Examples 1-3, the TPS obtained in Comparative Example 2, and the PBAT / TPS-RC and PBAT / TPS blend particles obtained in Example 3 and Comparative Example 2 were hot-pressed into sheets and subjected to a "U"-shape test. The samples were softened in a 100°C silicone oil bath, then bent into a "U" shape and quickly placed in 0°C silicone oil for 40 seconds to set. Finally, the "U"-shaped samples were placed in 100°C silicone oil, and the recovery was observed and recorded. The test results are as follows: Figure 1 , 3 As shown in Tables 2 and 3. From Figure 1 As shown in Table 2, Examples 1-3 exhibit a higher recovery rate compared to Comparative Example 2. This indicates that the polycaprolactone finally grafted onto the starch chain not only provides the fixing force to ensure temporary shape stability but also guarantees the shrinkage force to restore the original permanent shape, successfully realizing the excellent shape memory properties of TPS-RC. Figure 3 As shown in Table 3, pure PBAT did not exhibit any shape memory properties. Due to the introduction of TPS-RC, the strong hydrogen bond network of TPS-RC itself endowed it with weak shape memory characteristics, with a recovery rate of 83%. Polycaprolactone, acting as a switch, increased or decreased the temperature under external environmental stimuli to promote or restrict the movement of surrounding molecular chains. By increasing the temperature, PBAT / TPS-RC achieved excellent thermally driven shape memory properties, with a shape recovery rate of 97% under thermally driven conditions of 20-40 s.

[0085] Table 2. TPS and TPS-RC "U"-shaped tests

[0086]

[0087] Table 3. "U"-shaped test of PBAT / TPS and PBAT / TPS-RC

[0088]

[0089] 4. Microwave recovery test:

[0090] The products obtained in Examples 3 and 5 and Comparative Examples 1 and 2 were hot-pressed into sheets and cut into 50×5×1mm pieces. 3 A spline was constructed, and a cross-section (l0) with a center length of 30 mm was drawn. The spline was then suspended under a 300 g load in a high humidity (90% HR) environment. After 2 hours, it was removed, and the length of the central portion was measured and recorded as l1. Finally, the deformed spline was placed in a 700 W microwave oven, set to medium-high temperature, and the recovery was observed and recorded. The final length was recorded as l2. The recovery rate R was calculated as follows:

[0091] R = (l1-l2) / (l1-l0) × 100% Microwave recovery test results are as follows: Figure 4As shown in Table 4, Comparative Example 1 demonstrates that the deformed pure PBAT cannot be recovered after microwave heating. However, because glycerol, the polar plasticizer in TPS-RC, acts as a strong microwave absorber, it can rapidly heat up PBAT / TPS-RC by absorbing microwave energy, perfectly realizing the excellent microwave-driven shape memory performance of PBAT / TPS-RC. Therefore, Comparative Example 2 and Examples 3 and 5 all exhibit varying degrees of recovery. Example 5 even achieves a 100% complete recovery rate within 20 seconds.

[0092] Table 4 Microwave recovery test results of the products obtained from the comparative examples and embodiments.

[0093]

[0094] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A PBAT / TPS-RC composite material with dual shape memory, characterized in that: Includes 50-70 parts by weight of PBAT, 30-50 parts by weight of TPS-RC material, and 0.5-3 parts by weight of coupling agent; The TPS-RC material comprises 70-85 parts by weight of polycaprolactone-grafted starch and 15-30 parts by weight of polar plasticizer. The raw materials for polycaprolactone-grafted starch include 70-85 parts by weight of starch, 700-850 parts by weight of water, 10-100% by weight of caprolactone by starch mass, and 0.1-1 mol% by weight of caprolactone monomer as catalyst; the caprolactone is a product of polycaprolactone through efficient closed-loop recovery via thermal decomposition, comprising 90-100 wt% caprolactone monomer, with the remainder being caprolactone dimer and caprolactone trimer; The TPS-RC material is prepared by the following method: (1) Add starch to water, gelatinize, add caprolactone premix, add catalyst, and carry out in-situ ring-opening polymerization to obtain polycaprolactone-grafted starch. The gelatinization temperature is 70-100℃; the time is 1-3 hours. The premixing temperature is 70-100℃; the time is 5-15h; The in-situ ring-opening polymerization reaction is carried out at a temperature of 100-130℃ for 5-15 hours. (2) Polycaprolactone-grafted starch is mixed with a polar plasticizer and blended to obtain TPS-RC material.

2. The PBAT / TPS-RC composite material with dual shape memory according to claim 1, characterized in that: The starch is at least one of corn starch, tapioca starch, and potato starch.

3. The PBAT / TPS-RC composite material with dual shape memory according to claim 1, characterized in that: The catalyst is at least one of the following: stannous isooctanoate, cesium hydroxide monohydrate, HND580 solid acid catalyst, magnesium chloride hexahydrate, and stannous chloride. The polar plasticizer is at least one of glycerol, ethylene glycol, pentaerythritol, sorbitol, urea, and formamide.

4. The PBAT / TPS-RC composite material with dual shape memory according to claim 1, characterized in that: After mixing in step (2), let it stand for 8-16 hours; The blending in step (2) is melt blending, including at least one of extrusion, internal mixing, injection molding, and open mixing; The extruder used for blending in step (2) is a co-rotating parallel twin-screw extruder; the parameters of the extruder are set as follows: the temperature range from the extruder feed port to the die head is 80-160℃, and the screw speed is 80-120 r / min.

5. The PBAT / TPS-RC composite material with dual shape memory according to claim 1, characterized in that: The coupling agent is at least one of KH550, KH570, DL-411, and LK-201.

6. The application of the PBAT / TPS-RC composite material with dual shape memory as described in any one of claims 1 to 5 in fully biodegradable materials.

7. The application of the PBAT / TPS-RC composite material with dual shape memory as described in claim 6 in fully biodegradable materials, characterized in that: The specific application involves preparing PBAT / TPS-RC composite material into a film using a blow molding machine; The blow molding machine is a single-screw extrusion blow molding machine; the parameters are set as follows: film thickness 0.03-0.05 mm, film blow-up ratio 0.5-2.5, extruder screw speed 70-100 rpm, and temperature 140-150℃.

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