Crosslinked PBAT with high reaction activity and dynamically adjustable structure, preparation method of crosslinked PBAT and application of PLA in toughening

Abstract

The invention discloses cross-linked PBAT (poly (butylene adipate-co-terephthalate)) with high reaction activity and dynamically adjustable structure, a preparation method of the cross-linked PBAT and application of the cross-linked PBAT in toughening of PLA (polylactic acid). On the basis of a dynamic vulcanization method, a cross-linking agent with carbon-carbon double bonds and glycidyl acrylate substances are added into PBAT, under the initiation action of a peroxide initiator and the action of high temperature and high shear force, cross-linked PBAT with high reaction activity and a dynamically adjustable structure is prepared, and the cross-linked PBAT and PLA are subjected to melt blending, so that toughening of PLA can be realized; the preparation method is energy-saving and environment-friendly, and the prepared PLA / PBAT alloy material is excellent in mechanical property and has ultrahigh toughness.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polymer additives and PLA toughening, in particular to a cross-linked PBAT with high reactivity and dynamically adjustable structure, a preparation method thereof, and application in a PLA toughening system. TECHNICAL BACKGROUND

[0002] With the continuous development of society, the consumption of traditional petroleum-based materials is increasing, and the white garbage generated by its large-scale use causes serious pollution to the environment. People begin to look for biodegradable materials to replace traditional petroleum-based materials. Polylactic acid (PLA) is widely used in food packaging, medical devices and other fields due to its high strength, high modulus and good biocompatibility, and has become one of the most widely used biodegradable materials. However, the problem of high brittleness greatly limits its application field. In order to improve the problem of high brittleness of polylactic acid, the commonly used technology involves blending it with flexible bio-based and degradable polymers to prepare alloy materials to improve its toughness.

[0003] Poly(butylene adipate-co-terephthalate) (PBAT) is a thermoplastic biodegradable plastic, which is copolymerized by poly(butylene adipate) (PBA) and poly(butylene terephthalate) (PBT). It has good ductility, elongation at break, heat resistance and impact performance, and also has good biodegradability. Therefore, PBAT can well make up for the shortcomings of PLA in toughness and improve the toughness of PLA. Therefore, PLA can be compounded with PBAT, which is expected to obtain a degradable super-tough PLA material.

[0004] However, there is a problem of poor compatibility between PLA and PBAT in the composite. In order to obtain high-performance PLA / PBAT alloy material, the compatibility of PLA and PBAT needs to be further improved. The main ways to increase compatibility are inorganic particle compatibilization and reactive compatibilization. Among them, inorganic particles are prone to agglomeration, which affects the mechanical properties of the alloy, and are not considered as the best compatibilization method. Most reactive compatibilizers often involve different interfacial tensions between the two polymers. It is difficult for the reactive compatibilizer with too large molecular weight to migrate to the interface between the two phases, resulting in low compatibilization efficiency.

[0005] In view of the deficiencies in the prior art, the present application first designs a cross-linked PBAT elastomer with high reactivity and dynamically adjustable structure, which is applied to a PLA toughening system. The structure of the cross-linked PBAT elastomer can effectively control stress dissipation, and the high reactivity is used to improve the compatibility of the elastomer and PLA in the subsequent process, thereby improving the mechanical properties of the alloy. The present application not only improves the toughness of PLA, but also reduces the disadvantage of excessive decrease in the strength of PLA caused by the introduction of the elastomer, that is, a high-performance green fully biodegradable PLA-based composite material is obtained. SUMMARY

[0006] The application aims to provide a cross-linked PBAT with high reactivity and dynamically adjustable structure, and a preparation method thereof and application of the cross-linked PBAT in toughening of PLA.

[0007] The technical solution of the application is as follows.

[0008] A cross-linked PBAT with high reactivity and dynamically adjustable structure is prepared by the following method.

[0009] PBAT particles, a cross-linking agent containing carbon-carbon double bonds, glycidyl acrylate substances and a peroxide initiator are uniformly mixed to obtain a premix; the premix is melt blended and extruded by a twin-screw extruder to obtain the cross-linked PBAT with high reactivity and dynamically adjustable structure.

[0010] In the formula, n is 1 or 2.

[0011] Before use, the PBAT particles are pretreated as follows: the PBAT particles are dried in a 60-80℃ (preferably 60℃) air-drying oven for 6-8h (preferably 8h) and are ready for use.

[0012] The cross-linking agent containing carbon-carbon double bonds is selected from triallyl isocyanurate (TAIC), pentaerythritol tetraacrylate (PETTA) or 1,3-diisopropenyl benzene (1,3-DIPB); the addition amount of the cross-linking agent containing carbon-carbon double bonds is 0.1-1.0wt% of the mass of the PBAT particles, and the optimal addition amount is 0.5wt%.

[0013] The glycidyl acrylate substances are selected from glycidyl acrylate ether (AGE) or glycidyl methacrylate (GMA); the addition amount of the glycidyl acrylate substances is 1.0-6.0wt% of the mass of the PBAT particles, and the optimal addition amount is 4.0wt%.

[0014] The peroxide initiator is selected from dicumyl peroxide (DCP) or 1,4-bis(tert-butylperoxyisopropyl) benzene (BIBP); the addition amount of the peroxide initiator is 0.1-0.4wt% of the mass of the PBAT particles, and the optimal addition amount is 0.1wt%.

[0015] The feeding screw rotation speed of the twin-screw extruder is set to 20-50rpm, and the optimal rotation speed is 30rpm; the main screw rotation speed is set to 60-100rpm, and the optimal rotation speed is 80rpm; and the temperature of the twin-screw extruder is set to 130-150℃.

[0016] The cross-linked PBAT with high reactivity and dynamically adjustable structure can be used in a PLA toughening system, and therefore the application also relates to a super-high-toughness PLA / PBAT alloy, and a preparation method thereof is as follows:

[0017] After the PLA and the cross-linked PBAT are dried, the PLA and the cross-linked PBAT are uniformly mixed to obtain a premix; the premix is subjected to melt blending and extrusion granulation through a double-screw extruder to obtain PLA / PBAT alloy granules.

[0018] The drying temperature of the PLA and the cross-linked PBAT is 60-80 DEG C (preferably 80 DEG C), and the drying time is 6-8 h (preferably 6 h);

[0019] Based on the total mass of the PLA / PBAT alloy granules, the mass ratio of the cross-linked PBAT is 20-50 wt%, and the optimal mass ratio is 30 wt%;

[0020] The feeding screw rotation speed of the double-screw extruder is set to 20-50 rpm, and the optimal rotation speed is 30 rpm; the main screw rotation speed is set to 60-100 rpm, and the optimal rotation speed is 80 rpm; and the temperature of the double-screw extruder is set to 170-190 DEG C.

[0021] The technical principle of the application comprises:

[0022] Firstly, based on the dynamic vulcanization method, a cross-linking agent with carbon-carbon double bonds and a glycidyl acrylate substance are added to PBAT, under the initiation of a peroxide initiator and the action of high temperature and high shear force, a cross-linked PBAT with high reactivity and dynamically adjustable structure is prepared.

[0023] Secondly, the obtained cross-linked PBAT (i.e. modified PBAT) is melt blended with PLA to realize the toughening of PLA. In the melt blending process, the epoxy groups in the modified PBAT undergo ring-opening reaction with the end groups of PLA, and the free radicals generated from the C=C double bonds on the modified PBAT attack the active hydrogen on the PLA molecular chain, and the two reactions synergistically form a PLA-PBAT co-crosslinking structure. This structure is beneficial to enhancing the interfacial bonding force of the two phases and improving the compatibility of the PLA / PBAT alloy.

[0024] In addition, the PBAT with dynamically adjustable structure as a dispersed phase can produce local shear yielding to control stress dissipation when the alloy is subjected to impact. The adjustable structure of the dispersed phase and the high interfacial bonding force endow the PLA / PBAT alloy with excellent mechanical properties, and the alloy has super-high toughness.

[0025] In the present application, the "structure dynamic adjustable" of PBAT means that: by controlling the adding amount of crosslinking agent containing carbon-carbon double bond (such as: PETTA) and glycidyl acrylate (such as: GMA), PBAT with different crosslinking degree is prepared in a dynamic vulcanization way. The crosslinking degree of PBAT increases with the increase of the adding amount of GMA and PETTA. The essence of regulating the crosslinking degree of PBAT is to regulate the modulus of PBAT. When the adding amount of GMA is 4.0wt% and the adding amount of PETTA is 0.5wt% (Example 4), the modulus of PBAT reaches the optimum modulus required for stress dissipation control.

[0026] The present application has the advantages of:

[0027] In the present application, PLA and PBAT are both fully biodegradable materials, and the obtained PLA / PBAT is also a fully biodegradable alloy, which meets the current national requirements for energy saving and environmental protection. Through the synergistic effect of two kinds of additives (crosslinking agent containing carbon-carbon double bond and glycidyl acrylate), the dispersed phase structure of PLA / PBAT alloy material is dynamically adjustable and has high interfacial bonding force, and the ultra-high toughness PLA / PBAT alloy material is successfully prepared. The material realizes excellent mechanical properties with very small amount of additives. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 : Schematic diagram of modified PBAT preparation.

[0029] Figure 2 : Schematic diagram of PLA / PBAT alloy preparation.

[0030] Figure 3 : Alloy mechanism diagram.

[0031] Figure 4 : Infrared characterization of modified PBAT and PLA / PBAT alloy prepared in Example 4.

[0032] Figure 5 : Impact property test results and micro-morphology characterization of PLA / PBAT alloy prepared in Example 4. DETAILED DESCRIPTION

[0033] The present application will be further described below through specific examples, but the protection scope of the present application is not limited to this.

[0034] In the following examples,

[0035] The specific gravity of polylactic acid PLA (4032D) is 1.24g / cm 3 , and Mw is 1.8×105g / mol, which is provided by Nature Works LLC.

[0036] Polybutylene adipate-co-terephthalate butylene adipate-co-terephthalate PBAT (TH 801T) from Xinjiang Lanningsunhe Technology Co., Ltd., China.

[0037] Bis(1-(tert-butylperoxy)-1-methylethyl)-benzene (BIBP) was purchased from Changsha Zhongyi Chemical Co., Ltd.

[0038] Pentaerythritol tetraacrylate (PETTA) was provided by Arland Industry Co., Ltd. (Shanghai, China).

[0039] Example 1

[0040] The formulation and preparation method of modified PBAT are as follows:

[0041] PBAT resin: 100 wt%, PETTA: 0.5 wt%, GMA: 1.0 wt%, BIBP: 0.1 wt%.

[0042] (1) The PBAT resin was dried in an oven at 60°C for 8h before melt extrusion, and the dried raw materials were mixed in a high-speed mixer according to the formulation ratio to obtain a premix.

[0043] (2) The uniformly mixed raw materials in step (1) were added to the extruder, and the temperature of the extruder was set to 130-150°C. The feed screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. The modified PBAT masterbatch was obtained by melt blending, cooling and granulation.

[0044] The formulation and preparation method of the ultra-high toughness PLA / PBAT alloy are as follows:

[0045] PLA resin: 70 wt%, modified PBAT resin: 30 wt%

[0046] (1) The PLA resin and modified PBAT resin were dried in an oven at 80°C for 6h before melt extrusion, and the dried raw materials were mixed in a high-speed mixer according to the formulation ratio to obtain a premix.

[0047] (2) The uniformly mixed raw materials in step (1) were added to the extruder, and the temperature of the extruder was set to 170-190°C. The feed screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. The ultra-high toughness PLA / PBAT alloy masterbatch was obtained by melt blending, cooling and granulation.

[0048] Example 2

[0049] The formulation and preparation method of modified PBAT are as follows:

[0050] PBAT resin: 100wt%, PETTA: 0.5wt%, GMA: 2.0wt%, BIBP: 0.1wt%.

[0051] (1) The PBAT resin was dried in an oven at 60°C for 8h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to obtain a premix.

[0052] (2) The uniformly mixed raw materials in step (1) were added to an extruder, and the temperature of the extruder was set to 130-150°C. The feeding screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. The modified PBAT masterbatch was obtained by melt blending, cooling and granulation.

[0053] The formula and preparation method of the ultra-high toughness PLA / PBAT alloy are as follows:

[0054] PLA resin: 70wt%, modified PBAT resin: 30wt%

[0055] (1) The PLA resin and modified PBAT resin were dried in an oven at 80°C for 6h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to obtain a premix.

[0056] (2) The uniformly mixed raw materials in step (1) were added to an extruder, and the temperature of the extruder was set to 170-190°C. The feeding screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. The ultra-high toughness PLA / PBAT alloy masterbatch was obtained by melt blending, cooling and granulation.

[0057] Example 3

[0058] The formula and preparation method of the modified PBAT are as follows:

[0059] PBAT resin: 100wt%, PETTA: 0.5wt%, GMA: 3.0wt%, BIBP: 0.1wt%.

[0060] (1) The PBAT resin was dried in an oven at 60°C for 8h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to obtain a premix.

[0061] (2) The uniformly mixed raw materials in step (1) were added to an extruder, and the temperature of the extruder was set to 130-150°C. The feeding screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. The modified PBAT masterbatch was obtained by melt blending, cooling and granulation.

[0062] The formula and preparation method of the ultra-high toughness PLA / PBAT alloy are as follows:

[0063] PLA resin: 70wt%, modified PBAT resin: 30wt%

[0064] (1) The PLA resin, modified PBAT resin were dried in an oven at 80°C for 6h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to mix, to obtain a premix.

[0065] (2) The uniformly mixed raw materials in step (1) were added to an extruder, and the temperature of the extruder was set to 170-190°C. The feeding screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. After melt blending, cooling and granulation, the ultra-high toughness PLA / PBAT alloy masterbatch was obtained.

[0066] Example 4

[0067] The formula and preparation method of the modified PBAT are as follows:

[0068] PBAT resin: 100wt%, PETTA: 0.5wt%, GMA: 4.0wt%, BIBP: 0.1wt%.

[0069] (1) The PBAT resin was dried in an oven at 60°C for 8h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to mix, to obtain a premix.

[0070] (2) The uniformly mixed raw materials in step (1) were added to an extruder, and the temperature of the extruder was set to 130-150°C. The feeding screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. After melt blending, cooling and granulation, the modified PBAT masterbatch was obtained.

[0071] The free GMA, PETTA and linear PBAT were dissolved away by Soxhlet extraction, leaving the crosslinked PBAT gel insoluble and the structure change was studied by infrared spectroscopy. Figure 4 Figure e shows that the reactive micro-crosslinked PBAT still has a characteristic absorption peak at 910 cm -1 (epoxy group), indicating the successful grafting of GMA and showing reactivity, which can further react with PLA during subsequent melt blending.

[0072] The formula and preparation method of the ultra-high toughness PLA / PBAT alloy are as follows:

[0073] PLA resin: 70wt%, modified PBAT resin: 30wt%

[0074] (1) The PLA resin and modified PBAT resin were dried in an oven at 80°C for 6h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to obtain a premix.

[0075] (2) The uniformly mixed raw materials in step (1) were added to an extruder, and the temperature of the extruder was set to 170-190°C. The feeding screw rotation speed was set to 30 rpm, and the main screw rotation speed was set to 80 rpm. After melt blending and cooling, granulation was performed to obtain an ultra-high toughness PLA / PBAT alloy masterbatch (named: 5T40G).

[0076] Figure 4 In the present application, "Gel insolubles of composite material" and "Gel insolubles after extraction" both refer to the gel insolubles remaining after the free GMA, PETTA and linear PBAT, linear PLA are dissolved away by Soxhlet extraction of the alloy prepared in Example 4.

[0077] Figure 4 In the present application, (b) and (c) indicate that in the FT-IR spectrum of the gel extract of the PLA / PBAT alloy, the characteristic peaks belonging to PLA (1750cm -1 , 755cm -1 ) and PBAT (1710cm -1 , 729cm -1 ) appear simultaneously in the 1700-1800cm -1 (C=O stretching vibration) and 700-800cm -1 (C-H bending vibration) regions, confirming that the gel contains PLA and PBAT, i.e. both participate in crosslinking to form a PLA-PBAT co-crosslinked layer.

[0078] Figure 5 In the present application, "PLA / PBAT" refers to a pure physical mixing alloy, and "5T40G" refers to the alloy prepared in Example 4.

[0079] From the micro-morphology characterization, the fracture surface of "PLA / PBAT" (left) shows obvious debonding, which proves that the unmodified PLA / PBAT alloy relies on debonding between the two phases of PLA and PBAT to absorb energy when subjected to impact force, which means that the interfacial bonding force between the two phases is too poor, and the fundamental reason is incompatibility.

[0080] While the "5T40G" (right) debonding phenomenon disappeared, the fracture surface became rough, and obvious plastic deformation due to the shear yielding of the matrix was found. This means that when the alloy is impacted, due to the strong interfacial bonding force, the impact force can be transmitted from the continuous phase to the dispersed phase (PBAT), relying on the triaxial stress released by the cavitation of PBAT, and then transmitted again to the matrix around the dispersed phase through the strong interfacial bonding, to cause local shear yielding of the matrix, to absorb a large amount of impact energy, which is one of the main ways to improve the impact strength.

[0081] Example 5

[0082] The formula and preparation method of the modified PBAT are as follows:

[0083] PBAT resin: 100wt%, PETTA: 0.5wt%, GMA: 5.0wt%, BIBP: 0.1wt%.

[0084] (1) Dry the PBAT resin in an oven at 60°C for 8h before melt extrusion, and mix the dried raw materials in a high-speed mixer according to the formula proportion to obtain a premix.

[0085] (2) Put the uniformly mixed raw materials in step (1) into an extruder and set the temperature of the extruder to 130-150°C. Set the feeding screw speed to 30rpm and the main screw speed to 80rpm, and granulate the modified PBAT masterbatch after melt blending and cooling.

[0086] The formula and preparation method of the modified PBAT are as follows:

[0087] PLA resin: 70wt%, modified PBAT resin: 30wt%

[0088] (1) Dry the PLA resin and modified PBAT resin in an oven at 80°C for 6h before melt extrusion, and mix the dried raw materials in a high-speed mixer according to the formula proportion to obtain a premix.

[0089] (2) Put the uniformly mixed raw materials in step (1) into an extruder and set the temperature of the extruder to 170-190°C. Set the feeding screw speed to 30rpm and the main screw speed to 80rpm, and granulate the super-tough PLA / PBAT alloy masterbatch after melt blending and cooling.

[0090] Example 6

[0091] The formula and preparation method of the modified PBAT are as follows:

[0092] PBAT resin: 100wt%, PETTA: 1.0wt%, GMA: 4.0wt%, BIBP: 0.1wt%.

[0093] (1) The PBAT resin was dried in an oven at 60°C for 8h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to obtain a premix.

[0094] (2) The uniformly mixed raw materials in step (1) were added into an extruder, and the temperature of the extruder was set to 130-150°C. The feeding screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. The modified PBAT masterbatch was obtained by melt blending, cooling and granulation.

[0095] The formula and preparation method of the ultra-high toughness PLA / PBAT alloy are as follows:

[0096] PLA resin: 70wt%, modified PBAT resin: 30wt%

[0097] (1) The PLA resin and the modified PBAT resin were dried in an oven at 80°C for 6h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to obtain a premix.

[0098] (2) The uniformly mixed raw materials in step (1) were added into an extruder, and the temperature of the extruder was set to 170-190°C. The feeding screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. The ultra-high toughness PLA / PBAT alloy masterbatch was obtained by melt blending, cooling and granulation.

[0099] Example 7

[0100] The formula and preparation method of the modified PBAT are as follows:

[0101] PBAT resin: 100wt%, PETTA: 0.3wt%, GMA: 4.0wt%, BIBP: 0.1wt%.

[0102] (1) The PBAT resin was dried in an oven at 60°C for 8h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to obtain a premix.

[0103] (2) The uniformly mixed raw materials in step (1) were added into an extruder, and the temperature of the extruder was set to 130-150°C. The feeding screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. The modified PBAT masterbatch was obtained by melt blending, cooling and granulation.

[0104] The formula and preparation method of the ultra-high toughness PLA / PBAT alloy are as follows:

[0105] PLA resin: 70wt%, modified PBAT resin: 30wt%

[0106] (1) The PLA resin and the modified PBAT resin were dried in an oven at 80°C for 6h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to obtain a premix.

[0107] (2) The uniformly mixed raw materials in step (1) were added into an extruder, and the temperature of the extruder was set to 170-190°C. The feeding screw rotation speed was set to 30 rpm, and the main screw rotation speed was set to 80 rpm. The ultra-high toughness PLA / PBAT alloy master batch was obtained by melt blending, cooling and granulation.

[0108] Example 8

[0109] The formula and preparation method of the modified PBAT are as follows:

[0110] PBAT resin: 100wt%, PETTA: 0.5wt%, GMA: 4.0wt%, BIBP: 0.3wt%.

[0111] (1) The PBAT resin was dried in an oven at 60°C for 8h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to obtain a premix.

[0112] (2) The uniformly mixed raw materials in step (1) were added into an extruder, and the temperature of the extruder was set to 130-150°C. The feeding screw rotation speed was set to 30 rpm, and the main screw rotation speed was set to 80 rpm. The modified PBAT master batch was obtained by melt blending, cooling and granulation.

[0113] The formula and preparation method of the ultra-high toughness PLA / PBAT alloy are as follows:

[0114] PLA resin: 70wt%, modified PBAT resin: 30wt%

[0115] (1) The PLA resin and the modified PBAT resin were dried in an oven at 80°C for 6h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to obtain a premix.

[0116] (2) The uniformly mixed raw materials in step (1) were added into an extruder, and the temperature of the extruder was set to 170-190°C. The feeding screw rotation speed was set to 30 rpm, and the main screw rotation speed was set to 80 rpm. The ultra-high toughness PLA / PBAT alloy master batch was obtained by melt blending, cooling and granulation.

[0117] Example 9

[0118] The formula and preparation method of the modified PBAT are as follows:

[0119] PBAT resin: 100 wt%, PETTA: 0.1 wt%, GMA: 4.0 wt%, BIBP: 0.1 wt%.

[0120] (1) The PBAT resin was dried in an oven at 60°C for 8h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to mix, to obtain a premix.

[0121] (2) The uniformly mixed raw materials in step (1) were added to an extruder, and the temperature of the extruder was set to 130-150°C. The feeding screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. After melt blending, cooling and granulation, modified PBAT masterbatch was obtained.

[0122] The formula and preparation method of the ultra-high toughness PLA / PBAT alloy are as follows:

[0123] PLA resin: 70 wt%, modified PBAT resin: 30 wt%

[0124] (1) The PLA resin and modified PBAT resin were dried in an oven at 80°C for 6h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to mix, to obtain a premix.

[0125] (2) The uniformly mixed raw materials in step (1) were added to an extruder, and the temperature of the extruder was set to 170-190°C. The feeding screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. After melt blending, cooling and granulation, ultra-high toughness PLA / PBAT alloy masterbatch was obtained.

[0126] Comparative Example 1

[0127] The difference from the examples is that no GMA is added in the system, and only a crosslinking agent is added when modifying PBAT.

[0128] The formula and preparation method of the modified PBAT are as follows:

[0129] PBAT resin: 100 wt%, PETTA: 0.1 wt%, GMA: 0 wt%, BIBP: 0.1 wt%.

[0130] (1) The PBAT resin was dried in an oven at 60°C for 8h before melt extrusion, and the dried raw materials were added into a high-speed mixer according to the formula proportion to mix, to obtain a premix.

[0131] (2) The uniformly mixed raw materials in step (1) were added to an extruder, and the temperature of the extruder was set to 130-150°C. The feeding screw speed was set to 30 rpm, and the main screw speed was set to 80 rpm. After melt blending, cooling and granulation, modified PBAT masterbatch was obtained.

[0132] The formula and preparation method of the ultra-high toughness PLA / PBAT alloy are as follows:

[0133] PLA resin: 70wt%, modified PBAT resin: 30wt%

[0134] (1) The PLA resin and the modified PBAT resin were dried in an oven at 80°C for 6h before melt extrusion, and the dried raw materials were added into a high-speed mixer in the formula proportion to obtain a premix.

[0135] (2) The uniformly mixed raw materials in step (1) were added into an extruder, and the temperature of the extruder was set to 170-190°C. The feeding screw rotation speed was set to 30rpm, and the main screw rotation speed was set to 80rpm. The ultra-high toughness PLA / PBAT alloy master batch was obtained by melt blending, cooling and granulation.

[0136] Comparative Example 2

[0137] The difference from the example is that the raw material blending sequence of the PLA / PBAT alloy material, that is, all the raw materials are directly melt blended by one-pot method to obtain the PLA / PBAT alloy material.

[0138] The formula and preparation method of the ultra-high toughness PLA / PBAT alloy are as follows:

[0139] PLA resin: 70wt%, PBAT resin: 28.65wt%, PETTA: 0.15wt%, GMA: 1.2wt%, BIBP: 0.03wt%.

[0140] (1) The PLA resin and the PBAT resin were dried in an oven at 80°C for 6h before melt extrusion, and the dried raw materials were added into a high-speed mixer in the formula proportion to obtain a premix.

[0141] (2) The uniformly mixed raw materials in step (1) were added into an extruder, and the temperature of the extruder was set to 170-190°C. The feeding screw rotation speed was set to 30rpm, and the main screw rotation speed was set to 80rpm. The ultra-high toughness PLA / PBAT alloy master batch was obtained by melt blending, cooling and granulation.

[0142] Performance test results of the example

[0143] Performance test: refer to the national standard “GB / T 1040 Determination of tensile properties” and “GB / T 16420-1997 Determination of notched impact properties”.

[0144] Tensile property test: The tensile property was measured by using a universal tensile tester (Instron 5967, USA) at room temperature with a crosshead speed of 10 mm / min, and the result of each sample was expressed as the average value of at least five independent samples.

[0145] Impact property test: The notched impact property was measured by using an impact tester (SS-3700) at room temperature, and the result of each sample was expressed as the average value of at least five independent samples.

[0146] The test results of the examples and comparative examples are shown in Table 1.

[0147] Table 1: The results of the mechanical property test of PLA / BAT alloy

[0148]

[0149]

[0150] The innovative points of the present application and the principle of action are illustrated by the most optimal example 4 of the present application:

[0151] Between example 4 and comparative example 1, the difference is whether GMA is added or not. The fundamental reason is that PETTA as a crosslinking agent forms effective crosslinking sites inside PBAT, thereby causing the difference in modulus. However, the addition of PETTA only makes PBAT have "micro-crosslinking" but lacks "reactivity", which is provided by the epoxy groups on the PBAT molecular chain after grafting GMA. After adding GMA, the reactivity of "highly reactive and dynamically adjustable structure crosslinked PBAT" can be adjusted. Example 4 has high reactivity of PBAT (in-situ interface compatibilization with PLA, improving the compatibility between the two phases) and micro-crosslinking (triggering cavitation-shear yielding) to dissipate impact force and improve impact strength.

[0152] Between example 4 and comparative example 2, the difference is the blending sequence, which is actually the problem of "whether PBAT is pre-crosslinked". Example 4 is to first pre-crosslink PBAT to obtain reactive micro-crosslinked PBAT, and then perform in-situ interface compatibilization reaction with PLA. The alloy prepared in this way not only has good compatibility, but also the pre-crosslinked PBAT can trigger cavitation-shear yielding to dissipate impact energy. Comparative example 2 does not pre-crosslink PBAT, but directly melt-blends in one pot, which can provide relatively high compatibility, but linear PBAT is difficult to effectively trigger cavitation-shear yielding, so that its energy dissipation is not as good as that of the alloy in example 4.

[0153] The above embodiments are only preferred solutions, and the present application also includes other embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application. Any similar concept and step to the present application shall be included in the protection scope of the present application.

Claims

1. A cross-linked PBAT with high reactivity and dynamically tunable structure, characterized in that, It is prepared according to the following method: PBAT particles are mixed evenly with a crosslinking agent containing carbon-carbon double bonds, glycidyl acrylate, and a peroxide initiator to obtain a premix; the premix is ​​melt-blended and extruded into granules using a twin-screw extruder to obtain the crosslinked PBAT with high reactivity and dynamically adjustable structure. in, The crosslinking agent containing carbon-carbon double bonds is selected from: triallyl isocyanurate, pentaerythritol tetraacrylate or 1,3-diisopropenylbenzene; Glycidyl acrylates are selected from: glycidyl acrylate ethers or glycidyl methacrylates; The peroxide initiator is selected from: dicumyl peroxide or 1,4-di-tert-butyl peroxide.

2. The cross-linked PBAT with high reactivity and dynamically tunable structure as described in claim 1, characterized in that, The amount of crosslinking agent containing carbon-carbon double bonds added is 0.1 to 1.0 wt% of the PBAT particle mass.

3. The cross-linked PBAT with high reactivity and dynamically tunable structure as described in claim 1, characterized in that, The amount of glycidyl acrylate added is 1.0 to 6.0 wt% of the PBAT particle mass.

4. The cross-linked PBAT with high reactivity and dynamically tunable structure as described in claim 1, characterized in that, The amount of crosslinking agent containing carbon-carbon double bonds added is 0.5 wt% of the mass of PBAT particles, and the amount of glycidyl acrylate added is 4.0 wt% of the mass of PBAT particles.

5. The cross-linked PBAT with high reactivity and dynamically tunable structure as described in claim 1, characterized in that, The amount of peroxide initiator added is 0.1 to 0.4 wt% of the PBAT particle mass.

6. The cross-linked PBAT with high reactivity and dynamically tunable structure as described in claim 1, characterized in that, The feed screw speed of the twin-screw extruder is set to 20–50 rpm; the main screw speed is set to 60–100 rpm; and the temperature of the twin-screw extruder is set to 130–150℃.

7. The application of the cross-linked PBAT with high reactivity and dynamically tunable structure as described in claim 1 in the PLA toughening system.

8. A PLA / PBAT alloy with ultra-high toughness, characterized in that, It is prepared according to the following method: PLA and the cross-linked PBAT described in claim 1 are dried and then uniformly mixed to obtain a premix; the premix is ​​then melt-blended and extruded into granules using a twin-screw extruder to obtain PLA / PBAT alloy granules. Based on the total mass of PLA / PBAT alloy granules, the mass percentage of cross-linked PBAT is 20-50 wt%.

9. The ultra-high toughness PLA / PBAT alloy as described in claim 8, characterized in that, The feed screw speed of the twin-screw extruder is set to 20–50 rpm; the main screw speed is set to 60–100 rpm; and the temperature of the twin-screw extruder is set to 170–190℃.

Images