Oxazoline-terminated polyester chain-extended pla / pbat / tps composite material and preparation method thereof

Abstract

The application belongs to the technical field of high polymer materials, and specifically discloses an oxazoline-terminated polyester chain-extending PLA / PBAT / TPS composite material and a preparation method thereof.The oxazoline-terminated polyester chain-extending PLA / PBAT / TPS composite material provided by the application is prepared from the following raw materials: PLA, PBAT, thermoplastic starch TPS and a chain extender.The plasticizer used in the plasticizing treatment of the thermoplastic starch TPS contains three polar groups, i.e., a hydroxyl group, an amide group and a sulfonic acid group, so that the obtained thermoplastic starch TPS has high plasticizing efficiency and significantly improves the processability of the composite material.The polyester chain extender used in the application contains oxazoline groups at both ends, so that the PLA / PBAT / TPS composite material is chain-extended and the interfacial compatibility is enhanced, and the obtained PLA / PBAT / TPS composite material has excellent mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to an oxazoline-terminated polyester extended PLA / PBAT / TPS composite material, and also to its preparation method. Background Technology

[0002] With societal progress, plastics have become one of the most widely used materials in modern life. However, the extensive use of plastics causes environmental pollution, making biodegradable plastics a research hotspot for addressing this issue. Polylactic acid (PLA) is a novel biodegradable material with high tensile strength, high hardness, and excellent processing performance, making it an important biodegradable material. Polybutylene adipate terephthalate (PBAT) is a fully biodegradable aromatic polyester that combines the flexibility of PBA segments with the heat resistance and impact resistance of PBT segments. Blending PBAT with PLA can improve the brittleness of PLA, while adding starch can reduce costs and ensure the biodegradability of the composite material. However, the strong hydrogen bonding and high crystallinity of starch result in poor thermoplasticity and processing difficulties for natural starch, preventing the normal melt extrusion of PBAT / PLA composites with added starch. Currently, there are methods that use plasticizers to plasticize starch, produce thermoplastic starch resin (TPS), and then add it to PBAT and PLA. However, there are still problems with poor starch plasticization efficiency and poor processing performance.

[0003] Furthermore, due to the poor compatibility among PBAT, PLA, and TPS, chain extenders are currently needed to improve their compatibility in order to obtain high-performance composite materials. However, existing chain extenders are still insufficient in modifying the interfacial compatibility of the three components and require further improvement.

[0004] Based on the above problems, the present invention aims to provide a new PLA / PBAT / TPS composite material with good mechanical properties. Summary of the Invention

[0005] The purpose of this invention is to provide an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material, and also to provide its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] In a first aspect, the present invention provides an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material, the raw materials for which are prepared include: PLA, PBAT, thermoplastic starch TPS, and chain extender;

[0008] The thermoplastic starch TPS is starch treated with a plasticizer, and the plasticizer includes the chemical structural formula... The compound shown;

[0009] The chain extender is a polyester chain extender containing oxazoline end groups, including the chain extenders shown in Formula I and Formula II;

[0010]

[0011] In Equation I, the value of m ranges from 2000 to 4000.

[0012] In Equation II, the value of n ranges from 2000 to 4000.

[0013] In one embodiment of the present invention, the molecular weight of PLA in the raw materials for preparing the composite material is in the range of 25,000-35,000.

[0014] In one embodiment of the present invention, the molecular weight range of PBAT in the raw materials for preparing the composite material is 50,000-70,000.

[0015] In one embodiment of the present invention, the mass ratio of PBAT to PLA in the raw materials for preparing the composite material is (20-40):(60-80).

[0016] In one embodiment of the present invention, the mass ratio of thermoplastic starch (TPS) to PLA in the raw materials for preparing the composite material is (15-30):(60-80).

[0017] In one embodiment of the present invention, the mass ratio of the chain extender to the PLA in the raw materials for preparing the composite material is (0.5-2):(60-80).

[0018] In one embodiment of the present invention, the chain extender is a mixture of the chain extender shown in Formula I and the chain extender shown in Formula II. Preferably, the chain extender shown in Formula I and the chain extender shown in Formula II are mixed in a mass ratio of (1-2):(1-2).

[0019] As one embodiment of the present invention, the thermoplastic starch TPS is obtained by mixing starch with the plasticizer, wherein the starch and the plasticizer are mixed at a mass ratio of 100:(5-30).

[0020] As one embodiment of the present invention, the mixing process includes: mixing starch with the plasticizer, extruding using a twin-screw extruder, setting the temperature from zone one of the twin-screw extruder to the die head to 90-130°C, then cooling to 20-40°C, and drying to obtain the thermoplastic starch TPS.

[0021] As one embodiment of the present invention, the plasticizer is prepared using ethyl formate and 4-hydroxybenzenesulfonamide as raw materials, including the following steps: mixing the ethyl formate and the 4-hydroxybenzenesulfonamide in a molar ratio of (1-1.2):(1-1.2), using ethanol as a solvent, stirring and reacting at 40-60°C, and then evaporating the ethanol to obtain the plasticizer.

[0022] As one embodiment of the present invention, the chain extender shown in Formula I is prepared by reacting PBT with 2,2'-bis(2-oxazoline), including the steps of: mixing PBT with 2,2'-bis(2-oxazoline) and reacting at 190-200°C to obtain the chain extender shown in Formula I.

[0023] As one embodiment of the present invention, the chain extender shown in Formula II is prepared by reacting PBA with 2,2'-bis(2-oxazoline), including the steps of: mixing PBA with 2,2'-bis(2-oxazoline) and reacting at 190-200°C to obtain the chain extender shown in Formula II.

[0024] Secondly, the present invention provides a method for preparing the oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material of the present invention, comprising the steps of: mixing PLA, PBAT, thermoplastic starch TPS and chain extender, and then feeding the mixture into a twin-screw extruder, wherein the temperature of the twin-screw extruder is controlled at 150-190℃ and the screw speed is controlled at 100-300rpm, and the mixture is extruded and granulated by the twin-screw extruder to obtain the oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material.

[0025] As one embodiment of the present invention, the PLA, PBAT, thermoplastic starch TPS, and chain extender are mixed in an environment of 60-100°C for 10-30 minutes.

[0026] Thirdly, this invention provides an application of the oxazoline-terminated polyester extended PLA / PBAT / TPS composite material. The PLA / PBAT / TPS composite material provided by this invention possesses excellent mechanical properties and can be used in injection-molded products such as food containers and medical supplies, as well as blow-molded film products such as cling film, mulch film, and various packaging films.

[0027] The oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material provided by this invention is a novel high-molecular biodegradable material. The plasticizer used in the plasticizing treatment of the raw material, thermoplastic starch (TPS), contains three polar groups: hydroxyl, amide, and sulfonic acid groups. This plasticizing modification treatment of starch efficiently disrupts its crystal structure, making it processable and achieving thermoplasticization. The resulting thermoplastic starch TPS has high plasticizing efficiency, significantly improving the processing performance of the composite material. The polyester chain extender used contains oxazoline groups at both ends. Oxazoline groups are characterized by high activity, fast reaction speed, and no small molecule formation during the reaction. They can react with carboxylic acid groups to form amide groups, increasing the relative molecular weight of the polymer, improving thermal stability, and enhancing compatibility. The polyester chain extender provided by this invention is used in PLA / PBAT / TPS composite materials to extend the chain, thereby enhancing the interfacial compatibility among the three components and preparing a PLA / PBAT / TPS composite material with excellent mechanical properties. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below. Those skilled in the art should understand that the specific embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof.

[0029] It should be noted that, unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art.

[0030] In the following examples and comparative examples, the plasticizer preparation process used is as follows:

[0031] Ethyl formate and 4-hydroxybenzenesulfonamide were mixed in a molar ratio of 1:1, and ethanol was used as a solvent. The mixture was stirred at 50°C for 2 hours. The reaction formula is as follows. Afterward, the ethanol was removed by vacuum distillation to obtain the plasticizer.

[0032]

[0033] Preparation of thermoplastic starch (TPS): Starch and plasticizer are mixed at a mass ratio of 100:(5-30). Specifically, starch and plasticizer can be mixed at any other mass ratio within the range of 100:(5-30), such as 100:5, 100:10, 100:15, 100:20, 100:25, 100:30, or 100:(5-30).

[0034] The starch and plasticizer mixing process includes: mixing starch and plasticizer in a high-speed mixer, then extruding using a twin-screw extruder, setting the temperature from zone one to the die head of the twin-screw extruder to 90-130℃, then cooling to 20-40℃, and drying to obtain thermoplastic starch (TPS).

[0035] In the raw materials for preparing the composite material, the mass ratio of PBAT to PLA is (20-40):(60-80). Specifically, the mass ratio of PBAT to PLA can be any other ratio within the range of 20:60, 20:70, 20:80, 25:60, 25:70, 25:80, 30:60, 30:70, 30:80, 40:60, 40:70, 40:80, or (20-40):(60-80).

[0036] In the raw materials for preparing the composite material, the mass ratio of thermoplastic starch (TPS) to PLA is (15-30):(60-80). Specifically, the mass ratio of TPS to PLA can be any other ratio within the range of 15:60, 15:70, 15:80, 20:60, 20:70, 20:80, 25:60, 25:70, 25:80, 30:60, 30:70, 30:80, or (15-30):(60-80).

[0037] In the raw materials for preparing composite materials, the mass ratio of chain extender to PLA is (0.5-2):(60-80). Specifically, the mass ratio of chain extender to PLA can be any other ratio within the range of 0.5:60, 0.5:70, 0.5:80, 1.0:60, 1.0:70, 1.0:80, 1.5:60, 1.5:70, 1.5:80, 2.0:60, 2.0:70, 2.0:80, or (0.5-2):(60-80).

[0038] In the raw materials for preparing the composite material, the chain extender used is a mixture of the chain extender shown in Formula I and the chain extender shown in Formula II, which are mixed in a mass ratio of (1-2):(1-2). Specifically, the chain extender shown in Formula I and the chain extender shown in Formula II can be mixed in any other ratio within the range of 1:2, 1:1, 2:1, or (1-2):(1-2).

[0039] Unless otherwise specified, all other raw materials are commercially available regular products and can be obtained through purchase.

[0040] The following detailed explanation will be provided through specific examples.

[0041] Example 1

[0042] This embodiment provides an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material, prepared from the following raw materials: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:1.0.

[0043] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are mixed evenly at a mass ratio of 100:20 using a high-speed mixer, and then extruded using a twin-screw extruder. The temperature from zone one to the die head of the twin-screw extruder is set to 130°C, and then cooled to room temperature (about 25°C) and dried to obtain thermoplastic starch TPS.

[0044] The chain extender includes the chain extenders shown in Formula I and Formula II, which are mixed in a mass ratio of 1:1.

[0045]

[0046] The chain extender shown in Formula I is prepared by feeding terephthalic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 170℃ for 6 hours to obtain PBT with carboxyl groups at both ends, where m is 2500; the reaction formula is:

[0047]

[0048] PBT and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula I.

[0049] The chain extender shown in Formula II is prepared by feeding adipic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 170℃ for 6 hours to obtain PBA with carboxyl groups at both ends, where n is 2500; the reaction formula is:

[0050]

[0051] PBA and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula II.

[0052] The oxazoline-terminated polyester extended PLA / PBAT / TPS composite material provided in this embodiment is prepared by the following method:

[0053] PLA, PBAT, thermoplastic starch TPS, and chain extender were mixed in a high-speed mixer at 60℃ for 15 minutes at a mass ratio of 80:20:30:1.0. The mixture was then fed into a twin-screw extruder at a temperature of 180℃ and a screw speed of 150 rpm. The mixture was extruded and granulated to obtain an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material.

[0054] Example 2

[0055] This embodiment provides an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material, prepared from the following raw materials: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:1.5.

[0056] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are mixed evenly at a mass ratio of 100:25 using a high-speed mixer, and then extruded using a twin-screw extruder. The temperature from zone one to the die head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C) and dried to obtain thermoplastic starch TPS.

[0057] The chain extender includes the chain extenders shown in Formula I and Formula II, which are mixed in a mass ratio of 1:1.

[0058]

[0059] The chain extender shown in Formula I is prepared by feeding terephthalic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 180°C for 6 hours to prepare PBT with carboxyl groups at both ends. The reaction formula is the same as in Example 1, where m is 3500.

[0060] PBT and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula I.

[0061] The chain extender shown in Formula II is prepared by feeding adipic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 180°C for 6 hours to prepare PBA with carboxyl groups at both ends. The reaction formula is the same as in Example 1, where n is 3500.

[0062] PBA and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula II.

[0063] The oxazoline-terminated polyester extended PLA / PBAT / TPS composite material provided in this embodiment is prepared by the following method:

[0064] PLA, PBAT, thermoplastic starch TPS, and chain extender were mixed in a high-speed mixer at 80°C for 20 minutes at a mass ratio of 80:20:30:1.5. The mixture was then fed into a twin-screw extruder at a temperature of 180°C and a screw speed of 200 rpm. The mixture was extruded and granulated to obtain an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material.

[0065] Example 3

[0066] This embodiment provides an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material, prepared from the following raw materials: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:2.0.

[0067] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are mixed evenly at a mass ratio of 100:30 using a high-speed mixer, and then extruded using a twin-screw extruder. The temperature from zone one to the die head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C) and dried to obtain thermoplastic starch TPS.

[0068] The chain extender includes the chain extenders shown in Formula I and Formula II, which are mixed in a mass ratio of 1:1.

[0069]

[0070] The chain extender shown in Formula I is prepared by feeding terephthalic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 190°C for 6 hours to prepare PBT with carboxyl groups at both ends. The reaction formula is the same as in Example 1, where the value of m is 4000.

[0071] PBT and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula I.

[0072] The chain extender shown in Formula II is prepared by feeding adipic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 190°C for 6 hours to prepare PBA with carboxyl groups at both ends. The reaction formula is the same as in Example 1, where n is 4000.

[0073] PBA and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula II.

[0074] The oxazoline-terminated polyester extended PLA / PBAT / TPS composite material provided in this embodiment is prepared by the following method:

[0075] PLA, PBAT, thermoplastic starch TPS, and chain extender were mixed in a high-speed mixer at 80℃ for 20 minutes at a mass ratio of 80:20:30:2.0. The mixture was then fed into a twin-screw extruder at a temperature of 190℃ and a screw speed of 200 rpm. The mixture was extruded and granulated to obtain an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material.

[0076] Example 4

[0077] This embodiment provides an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material, prepared from the following raw materials: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:20:1.5.

[0078] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are mixed evenly at a mass ratio of 100:25 using a high-speed mixer, and then extruded using a twin-screw extruder. The temperature from zone one to the die head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C) and dried to obtain thermoplastic starch TPS.

[0079] The chain extender includes the chain extenders shown in Formula I and Formula II, which are mixed in a mass ratio of 1:1.

[0080]

[0081]

[0082] The chain extender shown in Formula I is prepared by feeding terephthalic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 180°C for 6 hours to prepare PBT with carboxyl groups at both ends. The reaction formula is the same as in Example 1, where m is 3500.

[0083] PBT and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula I.

[0084] The chain extender shown in Formula II is prepared by feeding adipic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 180°C for 6 hours to prepare PBA with carboxyl groups at both ends. The reaction formula is the same as in Example 1, where n is 3500.

[0085] PBA and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula II.

[0086] The oxazoline-terminated polyester extended PLA / PBAT / TPS composite material provided in this embodiment is prepared by the following method:

[0087] PLA, PBAT, thermoplastic starch TPS, and chain extender were mixed in a high-speed mixer at 80°C for 20 minutes at a mass ratio of 80:20:20:1.5. The mixture was then fed into a twin-screw extruder at a temperature of 180°C and a screw speed of 200 rpm. The mixture was extruded and granulated to obtain an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material.

[0088] Comparative Example 1

[0089] This comparative example provides an oxazoline-terminated polyester extended PLA / PBAT / TPS composite material, prepared from the following raw materials: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), and thermoplastic starch TPS; the mass ratio of PLA, PBAT, and thermoplastic starch TPS is 80:20:30.

[0090] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are mixed evenly at a mass ratio of 100:30 using a high-speed mixer, and then extruded using a twin-screw extruder. The temperature from zone one to the die head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C) and dried to obtain thermoplastic starch TPS.

[0091] The oxazoline-terminated polyester extended PLA / PBAT / TPS composite material provided in this comparative example is prepared by the following method:

[0092] PLA, PBAT, and thermoplastic starch TPS were mixed in a high-speed mixer at 80°C for 20 minutes at a mass ratio of 80:20:30. The mixture was then fed into a twin-screw extruder at a temperature of 190°C and a screw speed of 200 rpm. The mixture was extruded and granulated to obtain the PLA / PBAT / TPS composite material.

[0093] Comparative Example 2

[0094] This comparative example provides an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material, prepared from the following raw materials: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:1.5.

[0095] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are mixed evenly at a mass ratio of 100:25 using a high-speed mixer, and then extruded using a twin-screw extruder. The temperature from zone one to the die head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C) and dried to obtain thermoplastic starch TPS.

[0096] The chain extender is the chain extender shown in Formula I:

[0097]

[0098] The chain extender shown in Formula I is prepared by feeding terephthalic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 180°C for 6 hours to prepare PBT with carboxyl groups at both ends. The reaction formula is the same as in Example 1, where m is 3500.

[0099] PBT and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula I.

[0100] The oxazoline-terminated polyester extended PLA / PBAT / TPS composite material provided in this comparative example is prepared by the following method:

[0101] PLA, PBAT, thermoplastic starch TPS, and chain extender were mixed in a high-speed mixer at 80°C for 20 minutes at a mass ratio of 80:20:30:1.5. The mixture was then fed into a twin-screw extruder at a temperature of 180°C and a screw speed of 200 rpm. The mixture was extruded and granulated to obtain an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material.

[0102] Comparative Example 3

[0103] This comparative example provides an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material, prepared from the following raw materials: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:1.5.

[0104] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are mixed evenly at a mass ratio of 100:25 using a high-speed mixer, and then extruded using a twin-screw extruder. The temperature from zone one to the die head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C) and dried to obtain thermoplastic starch TPS.

[0105] The chain extender is the chain extender shown in Formula II;

[0106]

[0107] The chain extender shown in Formula II is prepared by feeding adipic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 180°C for 6 hours to prepare PBA with carboxyl groups at both ends. The reaction formula is the same as in Example 1, where n is 3500.

[0108] PBA and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula II.

[0109] The oxazoline-terminated polyester extended PLA / PBAT / TPS composite material provided in this comparative example is prepared by the following method:

[0110] PLA, PBAT, thermoplastic starch TPS, and chain extender were mixed in a high-speed mixer at 80°C for 20 minutes at a mass ratio of 80:20:30:1.5. The mixture was then fed into a twin-screw extruder at a temperature of 180°C and a screw speed of 200 rpm. The mixture was extruded and granulated to obtain an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material.

[0111] Comparative Example 4

[0112] This comparative example provides an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material, prepared from the following raw materials: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:4.

[0113] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are mixed evenly at a mass ratio of 100:25 using a high-speed mixer, and then extruded using a twin-screw extruder. The temperature from zone one to the die head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C) and dried to obtain thermoplastic starch TPS.

[0114] The chain extender includes the chain extenders shown in Formula I and Formula II, which are mixed in a mass ratio of 1:1.

[0115]

[0116] The chain extender shown in Formula I is prepared by feeding terephthalic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 180°C for 6 hours to prepare PBT with carboxyl groups at both ends. The reaction formula is the same as in Example 1, where m is 3500.

[0117] PBT and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula I.

[0118] The chain extender shown in Formula II is prepared by feeding adipic acid and butanediol in a molar ratio of 2:1, adding tetrabutyl titanate as a catalyst with a mass fraction of 5‰ of butanediol, and reacting at 180°C for 6 hours to prepare PBA with carboxyl groups at both ends. The reaction formula is the same as in Example 1, where n is 3500.

[0119] PBA and 2,2'-bis(2-oxazoline) were fed at a molar ratio of 1:2.2 and reacted at 190°C for 2 hours to obtain the polyester chain extender containing oxazoline end groups as shown in Formula II.

[0120] The oxazoline-terminated polyester extended PLA / PBAT / TPS composite material provided in this comparative example is prepared by the following method:

[0121] PLA, PBAT, thermoplastic starch TPS, and chain extender were mixed in a high-speed mixer at 80°C for 20 minutes at a mass ratio of 80:20:30:4. The mixture was then fed into a twin-screw extruder at a temperature of 180°C and a screw speed of 200 rpm. The mixture was extruded and granulated to obtain an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material.

[0122] Performance testing

[0123] The performance of the PLA / PBAT / TPS composite materials provided in the above embodiments and comparative examples was tested.

[0124] Tensile properties were tested using a universal electronic testing machine (DF-101S, High-speed Rail Testing Instruments Co., Ltd.) according to GB / T 1040.3-2006 standard, with a tensile rate of 50 mm / min.

[0125] The notched impact strength was tested using an impact testing machine (GT-7045-MDL type, Shenzhen High-speed Rail Testing Instruments Co., Ltd.) according to the GB / T 1043-2008 standard, with a pendulum energy of 5.5J.

[0126] The test results are shown in Table 1.

[0127] Table 1

[0128]

[0129]

[0130] As can be seen from the data in Table 1, compared with the composite materials provided in Comparative Examples 1-4, the tensile strength, elongation at break, and impact strength of the composite materials provided in Examples 1-4 of the present invention are significantly improved. Therefore, the oxazoline-terminated polyester extended PLA / PBAT / TPS composite material provided by the present invention exhibits excellent mechanical properties.

[0131] Comparative Example 4 increased the amount of chain extender in the raw materials for composite material preparation and found that the tensile strength, elongation at break, and impact strength of the resulting composite material decreased.

[0132] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material, characterized in that, The raw materials for preparation include: PLA, PBAT, thermoplastic starch TPS, and chain extender; The thermoplastic starch TPS is starch treated with a plasticizer, and the plasticizer includes the chemical structural formula... The compound shown; The chain extender is a polyester chain extender containing oxazoline end groups, including the chain extenders shown in Formula I and Formula II; Formula I; Formula II; The mass ratio of PBAT to PLA is (20-40):(60-80); the mass ratio of thermoplastic starch TPS to PLA is (15-30):(60-80); and the mass ratio of chain extender to PLA is (0.5-2):(60-80).

2. The composite material according to claim 1, characterized in that, The thermoplastic starch TPS is obtained by mixing starch with the plasticizer at a mass ratio of 100:(5-30).

3. The composite material according to claim 2, characterized in that, The mixing process includes: mixing starch with the plasticizer, extruding using a twin-screw extruder, setting the temperature from zone one of the twin-screw extruder to the die head to 90-130°C, then cooling to 20-40°C, and drying to obtain the thermoplastic starch TPS.

4. The composite material according to claim 1, characterized in that, The plasticizer is prepared using ethyl formate and 4-hydroxybenzenesulfonamide as raw materials, including the following steps: mixing ethyl formate and 4-hydroxybenzenesulfonamide in a molar ratio of (1-1.2):(1-1.2), using ethanol as a solvent, stirring and reacting at 40-60°C, and then evaporating the ethanol to obtain the plasticizer.

5. The composite material according to claim 1, characterized in that, The chain extender shown in Formula I is prepared by reacting PBT with 2,2'-bis(2-oxazoline), including the steps of mixing PBT with 2,2'-bis(2-oxazoline) and reacting at 190-200℃ to obtain the chain extender shown in Formula I.

6. The composite material according to claim 1, characterized in that, The chain extender shown in Formula II is prepared by reacting PBA with 2,2'-bis(2-oxazoline), including the steps of mixing PBA with 2,2'-bis(2-oxazoline) and reacting at 190-200℃ to obtain the chain extender shown in Formula II.

7. A method for preparing the composite material according to any one of claims 1-6, characterized in that, The process includes the following steps: mixing PLA, PBAT, thermoplastic starch TPS, and a chain extender, and then feeding the mixture into a twin-screw extruder. The temperature of the twin-screw extruder is controlled at 150-190℃, and the screw speed is controlled at 100-300rpm. The mixture is then extruded and granulated to obtain an oxazoline-terminated polyester chain extender PLA / PBAT / TPS composite material.

8. The method for preparing the composite material according to claim 7, characterized in that, The PLA, PBAT, thermoplastic starch TPS, and chain extender are mixed in an environment of 60-100℃ for 10-30 minutes.

9. The use of the composite material according to any one of claims 1-6 in food containers, packaging films or cling films.

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