Completely biodegradable thermoplastic starch blend and preparation method thereof

Abstract

The invention discloses a completely biodegradable thermoplastic starch blend and a preparation method thereof. The completely biodegradable thermoplastic starch blend comprises the following components in percentage by weight: 70%-80% of starch, 20%-30% of N-methylmorpholine-N-oxide and 2%-15% of polyethylene glycol. The starch can be one or more of wheat, corn, rice, sorghum and potatoes. The molecular weight of the polyethylene glycol is 200 to 10000. The preparation method adopts a melt blending method, and the melt blending temperature is less than or equal to 140 DEG C. The thermoplastic starch blend provided by the invention is completely biodegradable and has excellent mechanical properties, and the preparation method is simple and easy to implement.

Description

Technical Field

[0001] The present invention relates to a completely biodegradable thermoplastic material and a preparation method thereof, and particularly to a completely biodegradable thermoplastic starch blend and a preparation method thereof, belonging to the field of biodegradable polymer materials and products. Background Art

[0002] With the continuous emergence of advanced materials, the requirements of human beings for products are not only excellent performance, but also environmental friendliness of materials. Currently, the traditional plastic products under research not only consume a large amount of petroleum resources, but also are difficult to be degraded. The residual products after use will cause irreversible harm to the environment if they exist for a long time. Biodegradable materials have become a hot research topic, but most of the degradable materials generally face the problem of high cost, which limits their applications. Starch is the second most abundant natural polymer after cellulose, renewable, widely sourced and inexpensive, and is a green material that can be completely biodegradable. Due to the existence of a large number of hydrogen bonds in native starch, it does not have direct processability. Therefore, using a new type of plasticizer to plasticize it to form thermoplastic starch and obtain a blend composite material with excellent mechanical properties and complete environmental friendliness is an important research direction at present. Summary of the Invention

[0003] The purpose of the present invention is to provide a thermoplastic starch blend that is completely biodegradable, has excellent mechanical properties, novel raw materials, and a simple preparation method, and a preparation method thereof.

[0004] The technical solution for achieving the purpose of the present invention is: a completely biodegradable thermoplastic starch blend, comprising 70% - 80% of starch, 20% - 30% of N-methylmorpholine-N-oxide, and 2% - 15% of polyethylene glycol.

[0005] In the completely biodegradable thermoplastic starch blend of the present invention, the starch can be one or more of wheat, corn, rice, sorghum, and tubers.

[0006] In the completely biodegradable thermoplastic starch blend of the present invention, the molecular weight of the polyethylene glycol is 200 - 10000.

[0007] The preparation method of the completely biodegradable thermoplastic starch blend of the present invention successively includes the following steps:

[0008] (1) Mix the starch, N-methylmorpholine-N-oxide liquid, and polyethylene glycol;

[0009] (2) Use a screw extruder to melt and blend and extrude into a completely biodegradable thermoplastic starch blend.

[0010] Preparation method of completely biodegradable thermoplastic starch blend, the content of N-methylmorpholine-N-oxide in the N-methylmorpholine-N-oxide liquid must be ≥ 75%.

[0011] Preparation method of completely biodegradable thermoplastic starch blend, the melt blending temperature must be ≤ 140 °C.

[0012] The completely biodegradable thermoplastic starch blend and its preparation method of the present invention have the following remarkable advantages: (1) The N-methylmorpholine-N-oxide and polyethylene glycol adopted in the present invention are environmentally friendly. The thermoplastic starch blend of the present invention is completely biodegradable, has excellent mechanical properties, and is inexpensive; (2) The preparation method of the completely biodegradable thermoplastic starch blend of the present invention is simple and easy to operate, can thermoform products, and the forming method is simple and the cost is low. Specific implementation manners

[0013] The completely biodegradable thermoplastic starch blend of the present invention contains 70% - 80% of biomass material, 20% - 30% of N-methylmorpholine-N-oxide, and 2% - 15% of polyethylene glycol.

[0014] In the completely biodegradable thermoplastic starch blend of the present invention, the starch can be one or more of wheat, corn, rice, sorghum, and tubers. Tubers can be sweet potatoes, cassava, potatoes, etc. The "one or more" mentioned herein means two or more than two.

[0015] In the completely biodegradable thermoplastic starch blend of the present invention, the molecular weight of polyethylene glycol is 200 - 10000.

[0016] The preparation method of the completely biodegradable thermoplastic starch blend of the present invention successively includes the following steps:

[0017] (1) Mix the biomass material, N-methylmorpholine-N-oxide liquid, and polyethylene glycol;

[0018] (2) Use a screw extruder to melt blend and extrude into a completely biodegradable thermoplastic starch blend.

[0019] Preparation method of completely biodegradable thermoplastic starch blend, the content of N-methylmorpholine-N-oxide in the N-methylmorpholine-N-oxide liquid must be ≥ 75%. The content of N-methylmorpholine-N-oxide in the N-methylmorpholine-N-oxide liquid is preferably ≥ 80%. For example, the N-methylmorpholine-N-oxide liquid is N-methylmorpholine-N-oxide monohydrate.

[0020] Preparation method of completely biodegradable thermoplastic starch blend, the melt blending temperature must be ≤ 140 °C, preferably 100 - 120 °C.

[0021] Example 1

[0022] 380 g of dried corn starch and 120 g of N-methylmorpholine-N-oxide hydrate with 13.3 wt% water were heated to 105 °C for mixing and dissolution, and then mixed with 45 g of PEG 200 and 5 g of antioxidant 1010 at 105 °C. The mixed material was melt-blended and extruded in a micro twin-screw extruder. The working temperatures of the four sections of the extruder were set at 115 °C, 120 °C, 120 °C, and 120 °C respectively. After cooling by an air-cooled conveyor, it was pelletized by a micro pelletizer to obtain the completely biodegradable thermoplastic starch blend of the present invention. Then, dumbbell-shaped and rectangular specimens required for mechanical testing were injection-molded at 120 °C using an injection molding machine. The specimens were tested after being kept at a constant temperature and humidity of 25 °C and 50% relative humidity for 48 h. The tensile strength was 10.4 MPa and the impact strength was 6 kJ / m 2 。

[0023] Example 2

[0024] 380 g of dried wheat starch and 120 g of N-methylmorpholine-N-oxide hydrate with 13.3 wt% water were heated to 105 °C for mixing and dissolution, and then mixed with 45 g of PEG 1000 and 5 g of antioxidant 1010 at 105 °C. The mixed material was melt-blended and extruded in a micro twin-screw extruder. The working temperatures of the four sections of the extruder were set at 115 °C, 120 °C, 120 °C, and 120 °C respectively. After cooling by an air-cooled conveyor, it was pelletized by a micro pelletizer to obtain the completely biodegradable thermoplastic starch blend of the present invention. Then, dumbbell-shaped and rectangular specimens required for mechanical testing were injection-molded at 120 °C using an injection molding machine. The specimens were tested after being kept at a constant temperature and humidity of 25 °C and 50% relative humidity for 48 h. The tensile strength was 10.6 MPa and the impact strength was 3.1 kJ / m 2 。

[0025] Example 3

[0026] 380 g of dried wheat starch was mixed and dissolved by heating with 120 g of N-methylmorpholine-N-oxide hydrate containing 13.3 wt% water at 105 °C, and then mixed with 45 g of PEG 10000 and 5 g of antioxidant 1010 at 105 °C. The mixed material was melt-blended and extruded in a micro twin-screw extruder. The working temperatures of the four sections of the extruder were set at 115 °C, 120 °C, 120 °C, and 120 °C respectively. After cooling by an air-cooled conveyor, it was pelletized by a micro pelletizer to obtain the completely biodegradable thermoplastic starch blend of the present invention. Then, dumbbell-shaped and rectangular specimens required for mechanical testing were injection-molded at 120 °C using an injection molding machine. The specimens were tested after being kept at a constant temperature and humidity of 25 °C and 50% relative humidity for 48 h. The tensile strength was 10.3 MPa and the impact strength was 2.9 kJ / m 2 。

[0027] Example 4

[0028] 380 g of pre-dried wheat starch was mixed and dissolved by heating with 105 g of N-methylmorpholine-N-oxide hydrate containing 13.3 wt% water at 105 °C, and then mixed with 15 g of PEG 200 and 5 g of antioxidant 1010. The mixed material was melt-blended and extruded in a micro twin-screw extruder. The working temperatures of the four sections of the extruder were set at 115 °C, 120 °C, 120 °C, and 120 °C respectively. After cooling by an air-cooled conveyor, it was pelletized by a micro pelletizer to obtain the completely biodegradable thermoplastic starch blend of the present invention. Then, dumbbell-shaped and rectangular specimens required for mechanical testing were injection-molded at 120 °C using an injection molding machine. The specimens were tested after being kept at a constant temperature and humidity of 25 °C and 50% relative humidity for 48 h. The tensile strength was 6.6 MPa and the impact strength was 2.6 kJ / m 2 。

[0029] Example 5

[0030] 380 g of pre-dried wheat starch was mixed and dissolved by heating with 90 g of N-methylmorpholine-N-oxide hydrate containing 13.3 wt% water at 105 °C, and then mixed with 30 g of PEG 200 and 5 g of antioxidant 1010. The mixed material was melt-blended and extruded in a micro twin-screw extruder. The working temperatures of the four sections of the extruder were set at 115 °C, 120 °C, 120 °C, and 120 °C respectively. After cooling by an air-cooled conveyor, it was pelletized by a micro pelletizer to obtain the completely biodegradable thermoplastic starch blend of the present invention. Then, dumbbell-shaped and rectangular specimens required for mechanical testing were injection-molded at 120 °C using an injection molding machine. The specimens were tested after being kept at a constant temperature and humidity of 25 °C and 50% relative humidity for 48 h. The tensile strength was 8.8 MPa and the impact strength was 3.8 kJ / m 2 。

[0031] Example 6

[0032] 380 g of pre-dried wheat starch was mixed and dissolved with 60 g of N-methylmorpholine-N-oxide hydrate with a water content of 13.3 wt% at 105 °C, and then mixed with 60 g of PEG 200 and 5 g of antioxidant 1010. The mixed material was melt-blended and extruded in a micro twin-screw extruder. The working temperatures of the four sections of the extruder were set at 115 °C, 120 °C, 120 °C, and 120 °C respectively. After cooling by an air-cooled conveyor, it was pelletized by a micro pelletizer to obtain the fully biodegradable thermoplastic starch blend of the present invention. Then, dumbbell-shaped and rectangular specimens required for mechanical testing were injection-molded at 120 °C using an injection molding machine. The specimens were tested after being kept at a constant temperature and humidity of 25 °C and a relative humidity of 50% for 48 h. The tensile strength was 8.7 MPa, and the impact strength was 6.7 kJ / m 2 .

Claims

1. A fully biodegradable thermoplastic starch blend, characterized in that: Containing 70% - 80% starch, 20% - 30% N-methylmorpholine-N-oxide, and 2% - 15% polyethylene glycol.

2. The fully biodegradable thermoplastic starch blend according to claim 1, characterized in that: The starch is one or more of wheat, corn, rice, sorghum, and tubers.

3. The completely biodegradable thermoplastic starch blend according to claim 1 or 2, characterized in that: The molecular weight of the polyethylene glycol is 200 - 10000.

4. The preparation method of the fully biodegradable thermoplastic starch blend according to any one of claims 1 to 3, characterized in that: It sequentially includes the following steps: (1) Mix the starch, N-methylmorpholine-N-oxide liquid, and polyethylene glycol; (2) Use a screw extruder to melt and blend and extrude into a completely biodegradable thermoplastic starch blend.

5. The preparation method of the completely biodegradable thermoplastic starch blend according to claim 4, wherein: The content of N-methylmorpholine-N-oxide in the N-methylmorpholine-N-oxide liquid is ≥75%.

6. The preparation method of the fully biodegradable thermoplastic starch blend according to claim 4 or 5, characterized in that: The melt blending temperature is ≤140°C.