Preparation method and application of aluminum ion cluster dynamic crosslinking toughening PBAT / TPS photo-thermal repair function thermoplastic plastic

Abstract

The invention belongs to the technical field of biodegradable materials, and discloses a preparation method and application of aluminum ion cluster dynamic cross-linked toughened PBAT / TPS photo-thermal repair function thermoplastic plastic. The preparation method comprises the following steps: preparing the aluminum ion cluster, preparing the pre-plasticized starch, carrying out melt blending on the obtained pre-plasticized starch and the poly (butylene adipate-co-terephthalate), cooling and drying. Metal ions are complexed with lignin and thermoplastic starch TPS to form a metal ion dynamic network structure, so that the mechanical property of the material is remarkably improved, and the material is endowed with excellent photo-thermal repair performance. Meanwhile, the lignin and the starch are biomass materials, have degradability, are low in cost and easy to obtain, can effectively reduce the cost of the composite plastic, and are suitable for industrial large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of biodegradable materials, and specifically relates to a preparation method and application of aluminum ion cluster dynamically cross-linked and toughened PBAT / TPS photothermal repair functional thermoplastic plastics. Background Art

[0002] With the promotion of green living concepts, the use of biodegradable materials to replace non-degradable ones has attracted widespread attention. Polybutylene adipate terephthalate (PBAT) has become one of the most popular biodegradable materials due to its excellent ductility and processing properties. Thermoplastic starch (TPS) offers advantages such as low cost, renewable availability, and widespread availability. Blending TPS with a PBAT matrix can yield a composite material that combines the advantages of both. However, due to the poor compatibility between PBAT and TPS, the material exhibits poor properties such as breaking strength and elongation. While laboratory chemical modification can effectively improve these properties, the preparation process is complex and difficult to commercialize. Furthermore, current research on PBAT / TPS composites primarily focuses on improving mechanical, thermal, and barrier properties through the introduction of small molecule additives, limiting their application.

[0003] CN202410311220.X discloses a biodegradable PBAT / TPS composite ground film and its preparation method. By introducing a degradable crystalline crosslinker, PBAT and starch are crosslinked, inducing crystallization under the action of hydrazide groups, thereby improving the mechanical properties and heat resistance of the material. However, the method for preparing the crosslinker in this patent is complex, and the strength of the resulting composite film is relatively low. CN201610818079.8 discloses a completely biodegradable garbage bag film material and a method for preparing the garbage bag film. By modifying PBAT with nano-inorganic materials, introducing a PBAT compatibilizer, and filling the biomass material oyster shells, the film is blended with degradable polypropylene carbonate. The resulting composite film has excellent mechanical properties, but its preparation process is complex and cumbersome. CN202310746643.X discloses a PBAT / TPS composite material with high temperature and humidity resistance, high mechanical properties, and low migration, as well as its preparation and application. This patent introduces a soluble metal salt into the PBAT / TPS composite material to adjust the solubility parameter of the plasticizer (glycerol), improving the plasticizer's plasticizing effect on starch. Furthermore, the coordination of metal ions with TPS and glycerol enhances the material's mechanical properties. However, this patent primarily targets thin film materials, limiting its application.

[0004] Therefore, in the field of PBAT / TPS composite materials, it is of great significance to develop a biodegradable material with a simple preparation process, excellent mechanical properties, and further expand the application field of PBAT / TPS composite materials. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing aluminum ion cluster dynamically cross-linked and toughened PBAT / TPS photothermal repair functional thermoplastic plastics. The method has simple process, low cost, and is suitable for industrial production. The obtained PBAT / TPS plastic can be repaired under the action of light and heat and can maintain high mechanical properties after repair.

[0006] The technical solutions of the present invention are as follows: A method for preparing PBAT / TPS plastic comprises the following steps: (1) Mixing lignin with aluminum salt to obtain aluminum ion clusters; (2) mixing the aluminum ion cluster obtained in step (1) with starch and a starch plasticizer to obtain aluminum ion cluster-modified pre-plasticized starch; (3) The aluminum ion cluster modified pre-plasticized starch obtained in step (2) is melt-blended with polybutylene terephthalate-adipate (PBAT), and the PBAT / TPS plastic is obtained after cooling and drying.

[0007] Furthermore, the mixing method in step (1) is ball milling; and the ball milling time is 1-3 hours.

[0008] Furthermore, after the aluminum ion clusters are prepared in step (1), they are dried in an oven at a temperature below 80° C. for 5-24 hours.

[0009] Furthermore, the mixing method in step (2) is stirring; for example, stirring is performed using a high-speed stirrer for 0.1-0.5 h.

[0010] Furthermore, in step (2), the aluminum ion clusters are mixed with starch and starch plasticizer, and then sealed and allowed to stand at 20-30° C. for 10-24 hours to allow the metal ions to fully complex with the thermoplastic starch and lignin.

[0011] Furthermore, in step (1), the mass ratio of aluminum salt to lignin is (2-4):1; for example, 3:1, 7:3, 6.5:3.5.

[0012] Furthermore, in step (2), the ratio of the mass of the aluminum ion cluster to the sum of the mass of the starch and the starch plasticizer is (0.2-2):100; for example, 0.286:100, 0.429:100, 0.715:100, 1.07:100, 1.43:100, and 1.78:100.

[0013] Furthermore, the aluminum salt is selected from a mixture of one or more of aluminum chloride, aluminum sulfate, alum, and aluminum oxide.

[0014] Furthermore, the starch is selected from a mixture of one or more of corn starch, tapioca starch and potato starch.

[0015] Furthermore, the starch plasticizer is selected from a mixture of one or more of water, glycerol, propylene glycol, and sorbitol.

[0016] Furthermore, in the pre-plasticized starch modified with aluminum ion clusters obtained in step (2), the mass ratio of starch to starch plasticizer is 2-4:1, for example, 7:3, 8:3, 3:1, or 10:3.

[0017] Furthermore, in step (3), the mass ratio of PBAT to the pre-plasticized starch modified with aluminum ion clusters is 2-4:1, for example, 7:3, 8:3, 3:1, or 10:3.

[0018] Furthermore, the temperature of the melt blending in step (3) is 140-160° C., the rotation speed is 20-40 rpm, and the melting time is 10-20 min.

[0019] The present invention also provides a PBAT / TPS plastic prepared by the above method.

[0020] The present invention also provides the application of the PBAT / TPS plastic prepared by the above method in the field of biodegradable thermoplastic film materials.

[0021] The present invention effectively combines PBAT, TPS and lignin through dynamic cross-linking melt blending based on the multiple effects of aluminum ion clusters. It can effectively improve the mechanical properties of PBAT / TPS composite materials and give them photothermal repair functions while retaining the thermoplastic processing performance of the materials. By pre-spheroidizing the positively charged aluminum ions and the negatively charged lignin and mixing them, due to the strong electrostatic interaction between the aluminum ions and the lignin, the two aggregate to form aluminum ion clusters. After the generated aluminum ion clusters are introduced into the plasticization process of starch, the aluminum ions coordinate with the hydroxyl groups in the starch molecules to form a stable complex at room temperature. At high temperatures, the coordination bonds between the aluminum ions and the TPS groups dissociate, causing the pre-plasticized starch to exhibit thermoplastic processability. Simultaneously, under the high shear of a 140-160°C internal mixer, TPS and PBAT are molten, enhancing molecular chain mobility and resulting in a complex blend. Multiple supramolecular interactions are formed in the presence of aluminum ion clusters, including metal coordination between the aluminum ions and TPS, cation-π interactions between the aluminum ions and the aromatic terephthalic acid repeating units of PBAT, π-π conjugation between the aromatic lignin and the aromatic PBAT due to intermolecular p-orbital overlap, and multiple hydrogen bonds between the phenolic hydroxyl-rich lignin, the hydroxyl groups in TPS, and the carbonyl groups on the PBAT chains. These multiple supramolecular interactions, mediated by the aluminum ion clusters, significantly enhance the interactions between starch and PBAT chains. This also strengthens the interfacial forces between the otherwise incompatible PBAT and TPS phases, resulting in the excellent elongation at break of the PBAT / TPS material. On the other hand, the metal coordination bond energy formed between the aluminum ions in the aluminum ion cluster and TPS can synergize with lignin to effectively convert light energy into thermal energy, stimulate and activate the supramolecular interactions in the PBAT / TPS material, and reconstruct the material, thereby giving the material excellent photothermal repair function.

[0022] Compared with the prior art, the present invention has the following advantages and significant progress: (1) The present invention uses low-cost and biodegradable starch as a filler. During the starch plasticization process, aluminum ion clusters are introduced, and then melt-blended with PBAT. The introduced aluminum ion clusters can effectively complex with thermoplastic starch and lignin to form a dynamic metal ion cross-linked structure, effectively improving the dispersion of thermoplastic starch in the PBAT matrix. At the same time, through the metal coordination effect, the dispersibility of lignin is improved, reducing the stress concentration caused by lignin agglomeration. As a result, the mechanical properties of the composite plastic, especially the elongation at break, are significantly improved.

[0023] (2) The present invention introduces a metal ion coordination cross-linking structure into the material under molten conditions. The resulting product has high mechanical strength, a simple and efficient preparation process, a short reaction time, and is suitable for large-scale industrial production. The starch, PBAT, and lignin used are all degradable materials. Among them, starch and lignin are both biomass materials with a wide range of sources, which can effectively reduce the cost of composite materials. At the same time, the material also has the performance of photothermal repair. After photothermal repair, the material can still maintain high mechanical properties, which is of great significance for reducing the cost of degradable materials and expanding their application areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is further described with reference to the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention.

[0025] Figure 1 Schematic diagram of the design mechanism of the PBAT / TPS with dynamic cross-linking of aluminum ion clusters and photothermal repair; Figure 2 Schematic diagram of temperature-time curves of light-to-heat conversion of plastic samples obtained in Example 2 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0026] In order to make the present invention easier to understand, specific embodiments of the present invention will be further described below.

[0027] The preparation method of the aluminum ion cluster dynamically cross-linked and toughened PBAT / TPS photothermal repair functional thermoplastic plastic of the present invention is as follows: Example 1 Step (1): AlCl3 and lignin were weighed separately in a mass ratio of 3:1, mixed, and spherical graphite was added for 2 h, and placed at 60°C for 12 h to obtain aluminum ion clusters.

[0028] Step (2): The aluminum ion cluster obtained in step (1) is mixed with starch and glycerol in a mass ratio of 1.43:70:30, stirred in a high-speed blender for 10 minutes, and after mixing evenly, placed in a sealed bag in an environment of 25°C for 12 hours to obtain aluminum ion cluster modified pre-plasticized starch.

[0029] Step (3): The aluminum ion cluster modified pre-plasticized starch obtained in step (2) and PBAT are melt-blended in an internal mixer at a mass ratio of 3:7, the internal mixer temperature is 150° C., and the internal mixer speed is 30 r / min.

[0030] Example 2 Step (1): AlCl3 and lignin were weighed separately in a mass ratio of 7:3, mixed and spherical graphite was added for 2 h, and placed at 60°C for 12 h to obtain aluminum ion clusters.

[0031] Step (2): The aluminum ion cluster obtained in step (1) is mixed with starch and glycerol in a mass ratio of 1.43:70:30, stirred in a high-speed blender for 10 minutes, and after mixing evenly, placed in a sealed bag in an environment of 25°C for 12 hours to obtain aluminum ion cluster modified pre-plasticized starch.

[0032] Step (3): The aluminum ion cluster modified pre-plasticized starch obtained in step (2) and PBAT are melt-blended in an internal mixer at a mass ratio of 3:7, the internal mixer temperature is 150° C., and the internal mixer speed is 30 r / min.

[0033] Example 3 Step (1): AlCl3 and lignin were weighed separately according to the mass ratio of AlCl3 to lignin being 6.5:3.5, mixed and spherical graphite was added for 2 hours, and placed at 60°C for 12 hours to obtain aluminum ion clusters.

[0034] Step (2): The aluminum ion cluster obtained in step (1) is mixed with starch and glycerol in a mass ratio of 1.43:70:30, stirred in a high-speed blender for 10 minutes, and after mixing evenly, placed in a sealed bag in an environment of 25°C for 12 hours to obtain aluminum ion cluster modified pre-plasticized starch.

[0035] Step (3): The aluminum ion cluster modified pre-plasticized starch obtained in step (2) and PBAT are melt-blended in an internal mixer at a mass ratio of 3:7, the internal mixer temperature is 150° C., and the internal mixer speed is 30 r / min.

[0036] Example 4 Step (1): AlCl3 and lignin were weighed separately in a mass ratio of 7:3, mixed and spherical graphite was added for 2 h, and placed at 60°C for 12 h to obtain aluminum ion clusters.

[0037] Step (2): The aluminum ion cluster obtained in step (1) is mixed with starch and glycerol in a mass ratio of 0.715:70:30, stirred in a high-speed blender for 10 minutes, and after mixing evenly, placed in a sealed bag in an environment of 25°C for 12 hours to obtain aluminum ion cluster modified pre-plasticized starch.

[0038] Step (3): The aluminum ion cluster modified pre-plasticized starch obtained in step (2) and PBAT are melt-blended in an internal mixer at a mass ratio of 3:7, the internal mixer temperature is 150° C., and the internal mixer speed is 30 r / min.

[0039] Example 5 Step (1): AlCl3 and lignin were weighed separately in a mass ratio of 7:3, mixed and spherical graphite was added for 2 h, and placed at 60°C for 12 h to obtain aluminum ion clusters.

[0040] Step (2): The aluminum ion cluster obtained in step (1) is mixed with starch and glycerol in a mass ratio of 1.07:70:30, stirred in a high-speed blender for 10 minutes, and after mixing evenly, placed in a sealed bag in an environment of 25°C for 12 hours to obtain aluminum ion cluster modified pre-plasticized starch.

[0041] Step (3): The aluminum ion cluster modified pre-plasticized starch obtained in step (2) and PBAT are melt-blended in an internal mixer at a mass ratio of 3:7. The internal mixer temperature is 150° C. and the internal mixer speed is 30 r / min.

[0042] Comparative Example 1 Step (1): Starch and glycerol in a mass ratio of 7:3 were stirred in a high-speed blender for 10 minutes. After mixing evenly, the mixture was placed in a sealed bag at 25°C for 12 hours to obtain pre-plasticized starch.

[0043] Step (2): melt-blending the pre-plasticized starch obtained in step (1) with PBAT in a mass ratio of 3:7 in an internal mixer at a mixer temperature of 150° C. and a mixer speed of 30 r / min.

[0044] Comparative Example 2 Step (1): spheroidize the lignin for 2 hours and place it at 60°C for 12 hours to obtain the spheroidized lignin.

[0045] Step (2): The lignin after spheroidal graphite obtained in step (1) is mixed with starch and glycerol in a mass ratio of 0.43:70:30, stirred in a high-speed blender for 10 minutes, and after mixing evenly, placed in a sealed bag in an environment of 25°C for 12 hours to obtain pre-plasticized starch containing lignin.

[0046] Step (3): The lignin-containing pre-plasticized starch obtained in step (1) and PBAT are melt-blended in an internal mixer at a mass ratio of 3:7. The internal mixer temperature is 150° C. and the internal mixer speed is 30 r / min.

[0047] Comparative Example 3 Step (1): spheroidize AlCl3 for 2 hours and place it at 60℃ for 12 hours to obtain spheroidized AlCl3.

[0048] Step (2): The AlCl3 obtained in step (1) after spheroidal graphite is mixed with starch and glycerol in a mass ratio of 1:70:30, stirred in a high-speed blender for 10 minutes, and after mixing evenly, placed in a sealed bag in an environment of 25°C for 12 hours to obtain pre-plasticized starch containing AlCl3.

[0049] Step (3): 30 parts of pre-plasticized starch containing AlCl3 obtained in step (2) and 70 parts of PBAT are melt-blended in an internal mixer at a mixer temperature of 140-160°C and a mixer speed of 30 r / min.

[0050] Comparative Example 4 Step (1): AlCl3 and lignin were weighed separately in a mass ratio of 7:3, mixed and spherical graphite was added for 2 h, and placed at 60°C for 12 h to obtain aluminum ion clusters.

[0051] Step (2): The aluminum ion cluster obtained in step (1) is mixed with starch and glycerol in a mass ratio of 4.29:70:30, stirred in a high-speed blender for 10 minutes, and after mixing evenly, placed in a sealed bag in an environment of 25°C for 12 hours to obtain aluminum ion cluster modified pre-plasticized starch.

[0052] Step (3): The aluminum ion cluster modified pre-plasticized starch obtained in step (2) and PBAT are melt-blended in an internal mixer at a mass ratio of 3:7, the internal mixer temperature is 150° C., and the internal mixer speed is 30 r / min.

[0053] Comparative Example 5 Step (1): AlCl3 and lignin were weighed separately in a mass ratio of 7:3, mixed and spherical graphite was added for 2 h, and placed at 60°C for 12 h to obtain aluminum ion clusters.

[0054] Step (2): The aluminum ion cluster obtained in step (1) is mixed with starch and glycerol in a mass ratio of 0.143:70:30, stirred in a high-speed blender for 10 minutes, and after mixing evenly, placed in a sealed bag at 25°C for 12 hours to obtain aluminum ion cluster modified pre-plasticized starch.

[0055] Step (3): The aluminum ion cluster modified pre-plasticized starch obtained in step (2) and PBAT are melt-blended in an internal mixer at a mass ratio of 3:7, the internal mixer temperature is 150° C., and the internal mixer speed is 30 r / min.

[0056] Mechanical properties test: The products obtained in Examples 1-5 and Comparative Examples 1-5 were hot pressed into 1 mm thin plates at 150° C. and 10 MPa, and subjected to tensile performance tests (according to GB / T 10402-2006, the tensile rate was 100 mm / min). The test results are shown in Table 1.

[0057] Table 1 Components, mechanical properties and heat resistance of each comparative example and embodiment

[0058] like Figure 1 As shown, the dynamic cross-linking of aluminum ion clusters PBAT / TPS is mainly achieved by complexing metal ions with lignin and thermoplastic starch under molten conditions, effectively improving the dispersion of lignin and thermoplastic starch in PBAT and forming a dynamic cross-linking network of metal ions, thereby effectively enhancing the mechanical properties of the composite plastic and giving the material photothermal repair properties. As shown in Table 1, Comparative Example 1 is PBAT / TPS. Due to the poor compatibility of the system, TPS is difficult to disperse evenly in the PBAT matrix, easily agglomerates, and forms stress concentration points, resulting in a significant decrease in the mechanical properties of the material, which severely limits the application of the material. Comparative Example 2 adds lignin, which improves the compatibility of PBAT / TPS and gives the material photothermal repair properties, but the addition of lignin does not achieve the enhancement of the material. On the contrary, since lignin also agglomerates and produces stress concentration points, it seriously affects the mechanical properties of the composite plastic, and its elongation at break drops to 51.69% of the PBAT / TPS performance.

[0059] Compared with Comparative Example 1, the tensile strength of Example 2 increased by 49.33%, and the elongation at break increased by 327.27%. This is because under molten conditions, metal ions can form a complex structure with the hydroxyl-rich TPS phase, which can effectively improve the distribution of the TPS phase in the PBAT phase. Examples 1 to 3 are composite plastics of aluminum ion clusters dynamically cross-linked PBAT / TPS formed after the introduction of aluminum ion clusters. Compared with Comparative Example 1, the mechanical properties of the composite plastics modified by the aluminum ion clusters are effectively improved, especially in terms of elongation at break, which is significantly higher than PBAT / TPS. This is because the aluminum cations in the aluminum ion clusters form a cation-π effect with the aromatic lignin and the aromatic PBAT, which significantly enhances the interaction between the connected molecular chains, effectively suppresses the generation of stress concentration points caused by lignin agglomeration, and promotes the transmission of external stress in the material.

[0060] Sample photothermal performance test: The products obtained in Comparative Examples 1-3 and Example 2 were hot pressed into 1 mm thin plates at 150°C and 10 MPa, and the temperature changes of Comparative Examples 1-3 and Example 2 under near-infrared radiation (λ=808 nm, 1.5 W cm-2) were recorded using a thermal infrared camera.

[0061] The dumbbell-shaped tensile specimen of Example 2 was cut in the middle and irradiated with infrared radiation (λ = 808 nm, 1.5 W cm-2) for 90 s to obtain a photothermal repair specimen. The photothermal repair specimen was subjected to uniaxial stretching to test its mechanical properties.

[0062] like Figure 2 As shown in the figure, after irradiation with 808nm infrared light for 60s, the temperature of the PBAT / TPS sample in Comparative Example 1 remained almost unchanged. After the introduction of 1% by mass of metal ions in Example 2, the sample temperature rose rapidly from 25°C to 182°C. This is because the TPS phase in PBAT / TPS contains a large number of hydroxyl groups, which can effectively react with the metal ion Al + Forming metal ion coordination bonds, these metal ion coordination bonds can effectively convert light energy into heat energy; after the introduction of lignin in Comparative Example 2, the sample temperature increased from 25 ° C to 45.3 ° C, and also showed a certain photothermal effect. This is because lignin is a photothermal conversion material with good near-infrared photothermal conversion performance. Example 2 combines the advantages of lignin and metal ions to obtain higher photothermal conversion performance. After irradiation with 808 nm infrared light for 60 s, PBAT / TPS-L 0.43 -The temperature of Al1 increased from 25°C to 211°C.

[0063] As shown in Table 2, the fracture strength of the repaired specimen in Example 2 is 8.9 MPa, and the elongation at break is 663%, which are 87% and 81% of the original performance, respectively, and are still stronger than those in Comparative Example 1, indicating that Example 2 has excellent photothermal repair ability.

[0064] Table 2 Mechanical properties after photothermal repair of Example 6

[0065] The preparation method and process provided in the embodiments of the present invention can achieve synergistic enhancement of the effect of metal ions and lignin on PBAT / TPS materials, making them have high strength, toughness, biodegradability and photothermal repair properties, which is of great significance for reducing the cost of PBAT / TPS materials and expanding their application range.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing PBAT / TPS plastic, characterized in that: The steps include: (1) Mixing lignin with aluminum salt to obtain aluminum ion clusters; (2) mixing the aluminum ion cluster obtained in step (1) with starch and a starch plasticizer to obtain aluminum ion cluster-modified pre-plasticized starch; (3) The aluminum ion cluster modified pre-plasticized starch obtained in step (2) is melt-blended with polybutylene terephthalate-adipate (PBAT), and the PBAT / TPS plastic is obtained after cooling and drying.

2. The preparation method according to claim 1, characterized in that In step (1), the mass ratio of aluminum salt to lignin is (2-4):

1.

3. The preparation method according to claim 1, characterized in that In step (2), the ratio of the mass of the aluminum ion cluster to the sum of the mass of the starch and the starch plasticizer is (0.2-2):

100.

4. The preparation method according to claim 1, characterized in that The aluminum salt is selected from a mixture of one or more of aluminum chloride, aluminum sulfate, alum, and aluminum oxide.

5. The preparation method according to claim 1, characterized in that The starch is selected from a mixture of one or more of corn starch, tapioca starch, and potato starch; and the starch plasticizer is selected from a mixture of one or more of water, glycerol, propylene glycol, and sorbitol.

6. The preparation method according to claim 1, characterized in that In the pre-plasticized starch modified with aluminum ion clusters obtained in step (2), the mass ratio of starch to starch plasticizer is 2-4:

1.

7. The preparation method according to claim 1, characterized in that In step (3), the mass ratio of PBAT to pre-plasticized starch is 2-4:

1.

8. The preparation method according to claim 1, characterized in that The temperature of the melt blending in step (3) is 140-160° C., the rotation speed is 20-40 rpm, and the melting time is 10-20 min.

9. A PBAT / TPS plastic, characterized in that: The method according to any one of claims 1 to 8 is used to prepare the present invention.

10. Application of the PBAT / TPS plastic prepared by the method according to any one of claims 1 to 8 in the field of biodegradable thermoplastic film materials.

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