Algal fiber filled polylactic acid and method of making the same

Abstract

This invention discloses a polylactic acid (PLA) filled with seaweed fiber and its preparation method. The PLA filled with seaweed fiber is prepared by weight-based methods using 100 parts PLA, 20-100 parts seaweed fiber, 1-5 parts zinc borate, 0.5-5 parts γ-aminopropylsilanetriol, 0.5-3 parts antioxidant, and 0.1-3 parts lubricant. This invention introduces zinc borate and γ-aminopropylsilanetriol into the PLA filled with seaweed fiber, thereby significantly improving the mechanical and flame-retardant properties of PLA, providing prospects for the application of PLA materials in more fields.

Description

Technical Field

[0001] This invention belongs to the field of polymer material modification technology, specifically relating to a polylactic acid filled with seaweed fiber and its preparation method. Background Technology

[0002] Currently, common biodegradable plastics mainly include hydroxyl fatty acid ester (salt) polymers (PHAs), such as polylactic acid (PLA), polycaprolactone (PCL), and hydroxybutylamine-hydroxyvalerate copolyester (PHBV); aliphatic copolyesters, such as polybutylene succinate (PBS) and poly(butylene succinate-cobutylene adipate) (PBSA), or modified blends with polysaccharide structures, such as thermoplastic starch (TPS). Among these, polylactic acid (PLA) is made from starch derived from renewable plant resources (such as corn). However, it has low strength, is flammable, and drips excessively, which greatly limits its application in certain specific fields.

[0003] Adding flame retardants to PLA can impart flame-retardant properties, but considering that PLA is a biodegradable polymer, the selection of flame retardants must also consider whether their addition will compromise its biodegradability. Seaweed fiber, made from abundant brown algae found in the ocean, is a natural biomass-derived fiber produced through refined alginate polysaccharides and wet spinning deep processing technology. It is environmentally friendly, non-toxic, flame-retardant, biodegradable, biocompatible, and has abundant raw material sources. Seaweed fiber inherently possesses flame-retardant properties, with a limiting oxygen index >45%, and is self-extinguishing, non-dripping, and smokeless. There are already cases of using seaweed fiber as a flame-retardant component in fabrics, eliminating the need for chemical auxiliaries and leveraging its inherent performance advantages to enhance fabric flame retardancy.

[0004] However, the flame-retardant effect of seaweed fiber in polylactic acid (PLA) systems is not significant. Adding seaweed fiber directly to PLA cannot achieve the V0 flame retardancy rating in UL94. Furthermore, due to poor compatibility, the mechanical properties of PLA cannot be significantly improved. Summary of the Invention

[0005] In view of this, the primary objective of the present invention is to provide a polylactic acid filled with seaweed fiber, in which, through formulation optimization, the polylactic acid filled with seaweed fiber has high strength and excellent flame retardant properties.

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

[0007] The first aspect of the present invention provides a polylactic acid filled with seaweed fiber, which is prepared by weight of 100 parts polylactic acid, 20-100 parts seaweed fiber, 1-5 parts zinc borate, 0.5-5 parts γ-aminopropylsilanetriol, 0.5-3 parts antioxidant and 0.1-3 parts lubricant.

[0008] In some specific embodiments of the present invention, the polylactic acid has a melt index of 10-30 g / 10 min and the test conditions are 230 °C and 2.16 kg.

[0009] In some specific embodiments of the present invention, the zinc borate is a white powder with a purity of ≥98%.

[0010] In some specific embodiments of the present invention, the seaweed fiber is a short-cut fiber with an average fiber length of 5 to 30 mm.

[0011] The lubricant and antioxidant described in this invention are not particularly limited and can be of conventional types in the art. Specifically, the lubricant can be at least one of stearic acid, butyl stearate, oleamide, and ethylene bis-stearamide, but is not limited thereto.

[0012] The antioxidant can be at least one of hindered phenols, thiolated compounds, hindered amines, and phosphites. Specific examples include at least one of antioxidants 1076, 1098, 1010, 300, or 168, but are not limited thereto. In some specific embodiments of the present invention, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0013] The second aspect of this invention provides a method for preparing polylactic acid-filled seaweed fiber as described in the first aspect of this invention, comprising the following steps:

[0014] Weigh out 100 parts of polylactic acid, 20-100 parts of seaweed fiber, 1-5 parts of zinc borate, 0.5-5 parts of γ-aminopropylsilanetriol, 0.5-3 parts of antioxidant, and 0.1-3 parts of lubricant according to the following weight ratio;

[0015] Polylactic acid, zinc borate, γ-aminopropylsilanetriol, antioxidant and lubricant are thoroughly mixed to obtain a uniform premix.

[0016] The premixed material and seaweed fiber are fed into a twin-screw extruder through the main feed port and the side feed port, respectively, and then melt-extruded to obtain seaweed fiber-filled polylactic acid.

[0017] The mixing method is not particularly limited and any conventional mechanical mixing method in the art can be used. In some specific embodiments of the present invention, a high-speed mixer is used to mix the materials evenly. The specific speed, time, etc. can be adjusted as needed.

[0018] In a further embodiment, the temperature of the twin-screw extruder can be selected and optimized according to the specific composition of the polylactic acid composite material. In some specific embodiments of the present invention, the temperature of the twin-screw extruder is 130-180℃ in zone one, 180-200℃ in zone two, 200-210℃ in zone three, 210-215℃ in zone four, and 210-220℃ at the die head.

[0019] The beneficial effects of this invention are:

[0020] Seaweed fiber contains a large number of carboxyl and hydroxyl groups, which can absorb a large amount of moisture from the air. The vaporization of liquid water requires a significant amount of heat, thus lowering the surface temperature of the fiber and hindering heat accumulation and transfer, achieving a flame-retardant effect. The decarboxylation reaction of seaweed fiber produces a large amount of carbon dioxide, which dilutes the concentration of flammable gases, playing an auxiliary role in flame retardancy. During thermal decomposition, the carboxyl and hydroxyl groups in the seaweed fiber molecular chain react, dehydrating to form ester compounds, which inhibit the thermal decomposition of the fiber, reduce the generation of flammable gases, and promote char formation. This invention introduces zinc borate into the system based on seaweed fiber filled with polylactic acid. In the presence of zinc borate, seaweed fiber can form more char residue after combustion, and the resulting carbon layer is thicker and denser. When polylactic acid is present in both zinc borate and seaweed fiber, the flame-retardant performance of the composition is even better, reaching UL94 V0 level.

[0021] In this invention, γ-aminopropylsilanetriol is selected as a coupling agent to achieve excellent coupling effect between polylactic acid and seaweed fiber. Since the structure of γ-aminopropylsilanetriol is connected to an aminopropyl chain and three ethoxy groups through a silicon atom, it can chemically react with the surface of polylactic acid and seaweed fiber to form chemical bonds and enhance adhesion. Furthermore, γ-aminopropylsilanetriol can improve the physical compatibility between the components of the composition by increasing the surface energy, thereby increasing the contact area and adhesion, and thus significantly improving the mechanical strength of polylactic acid-filled seaweed fiber. Detailed Implementation

[0022] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. Furthermore, unless otherwise specified, methods not specifically describing conditions or steps are conventional methods, and the reagents and materials used are commercially available.

[0024] The specific raw material information in the following examples and comparative examples is as follows:

[0025] The polylactic acid used is Total L105 from Thailand, with a melt index of 14 g / 10 min, an elongation at break of 2.5%, and a tensile strength of 58 MPa.

[0026] γ-aminopropylsilanetriol, Hangzhou Jessica Chemical Co., Ltd.

[0027] Seaweed fiber is a short-cut fiber with an average fiber length of 20mm, manufactured by Qingdao Gecheng Jingwei Biotechnology Co., Ltd.

[0028] The zinc borate is a white powder with a purity of ≥98%, manufactured by Hefeng New Energy Co., Ltd.

[0029] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a 1:1 mass ratio, and the supplier is DuPont.

[0030] Henan Chuangxiang Chemical Products Co., Ltd. is a supplier of antimony trioxide.

[0031] The coupling agents KH550 and KH570 are both supplied by Jinan Shanhai Chemical Technology Co., Ltd.

[0032] Dongguan Zhengtao Plastics Co., Ltd. is a supplier of ethylene bis-stearamide lubricant.

[0033] Zhongshan Dixin Chemical Co., Ltd. is a supplier of butyl stearate, a lubricant.

[0034] It should be noted that the above-mentioned raw material information is provided only to make the technical solutions of the embodiments clearer and to ensure sufficient disclosure. It does not mean that the present invention can only use the above-mentioned raw materials. Raw materials from other manufacturers or with different parameters can also be used in the present invention to achieve the same effect. The specific scope of protection of the claims shall prevail.

[0035] Example 1

[0036] This embodiment discloses the composition and preparation method of one type of polylactic acid filled with seaweed fiber. The specific preparation method is as follows:

[0037] By weight, 100 parts of polylactic acid, 2 parts of zinc borate, 0.5 parts of γ-aminopropylsilanetriol, 0.5 parts of antioxidant, and 0.2 parts of lubricant ethylene bis-stearamide were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 25 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0038] The twin-screw extruder has a zone temperature of 140℃, a zone temperature of 190℃, a zone temperature of 200℃, a zone temperature of 210℃, and a die head temperature of 220℃.

[0039] Example 2

[0040] This embodiment discloses the composition and preparation method of one type of polylactic acid filled with seaweed fiber. The specific preparation method is as follows:

[0041] By weight, 100 parts of polylactic acid, 3 parts of zinc borate, 2 parts of γ-aminopropylsilanetriol, 1.5 parts of antioxidant, and 1 part of lubricant ethylene bis-stearamide were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 40 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0042] The twin-screw extruder has a zone temperature of 150℃, a zone temperature of 180℃, a zone temperature of 200℃, a zone temperature of 210℃, and a die head temperature of 210℃.

[0043] Example 3

[0044] This embodiment discloses the composition and preparation method of one type of polylactic acid filled with seaweed fiber. The specific preparation method is as follows:

[0045] By weight, 100 parts of polylactic acid, 3.5 parts of zinc borate, 2.5 parts of γ-aminopropylsilanetriol, 1.5 parts of antioxidant, and 1.5 parts of lubricant ethylene bis-stearamide were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 48 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0046] The twin-screw extruder has a zone temperature of 160℃, a zone temperature of 190℃, a zone temperature of 200℃, a zone temperature of 210℃, and a die head temperature of 210℃.

[0047] Example 4

[0048] This embodiment discloses the composition and preparation method of one type of polylactic acid filled with seaweed fiber. The specific preparation method is as follows:

[0049] By weight, 100 parts of polylactic acid, 4 parts of zinc borate, 3.5 parts of γ-aminopropylsilanetriol, 2 parts of antioxidant, and 2.5 parts of lubricant butyl stearate were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 60 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0050] The twin-screw extruder has a zone temperature of 180℃, a zone temperature of 200℃, a zone temperature of 210℃, a zone temperature of 215℃, and a die head temperature of 220℃.

[0051] Example 5

[0052] This embodiment discloses the composition and preparation method of one type of polylactic acid filled with seaweed fiber. The specific preparation method is as follows:

[0053] By weight, 100 parts of polylactic acid, 3.5 parts of zinc borate, 4 parts of γ-aminopropylsilanetriol, 2.5 parts of antioxidant, and 2 parts of lubricant butyl stearate were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 68 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0054] The twin-screw extruder has a zone temperature of 180℃, a zone temperature of 200℃, a zone temperature of 210℃, a zone temperature of 215℃, and a die head temperature of 220℃.

[0055] Example 6

[0056] This embodiment discloses the composition and preparation method of one type of polylactic acid filled with seaweed fiber. The specific preparation method is as follows:

[0057] By weight, 100 parts of polylactic acid, 3.5 parts of zinc borate, 5 parts of γ-aminopropylsilanetriol, 2 parts of antioxidant, and 2.5 parts of butyl stearate lubricant were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 80 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0058] The twin-screw extruder has a zone temperature of 180℃, a zone temperature of 200℃, a zone temperature of 210℃, a zone temperature of 215℃, and a die head temperature of 220℃.

[0059] Comparative Example 1

[0060] This comparative example discloses the composition and preparation method of one of the polylactic acid filled with seaweed fiber. It adopts the same implementation method as Example 5, except that 3.5 parts of zinc borate and 68 parts of seaweed fiber are replaced with 71.5 parts of seaweed fiber.

[0061] The specific preparation steps are as follows:

[0062] By weight, 100 parts of polylactic acid, 4 parts of γ-aminopropylsilanetriol, 2.5 parts of antioxidant, and 2 parts of lubricant butyl stearate were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 71.5 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0063] The twin-screw extruder has a zone temperature of 180℃, a zone temperature of 200℃, a zone temperature of 210℃, a zone temperature of 215℃, and a die head temperature of 220℃.

[0064] Comparative Example 2

[0065] This comparative example discloses the composition and preparation method of polylactic acid, using the same implementation method as Example 5, except that 3.5 parts of zinc borate and 68 parts of seaweed fiber are replaced with 71.5 parts of zinc borate.

[0066] The specific preparation steps are as follows:

[0067] By weight, 100 parts of polylactic acid, 71.5 parts of zinc borate, 4 parts of γ-aminopropylsilanetriol, 2.5 parts of antioxidant, and 2 parts of lubricant butyl stearate were poured into a high-speed mixer, mixed evenly, and then added to a twin-screw extruder. The mixture was then melt-extruded and granulated to obtain a polylactic acid composite material.

[0068] The twin-screw extruder has a zone temperature of 180℃, a zone temperature of 200℃, a zone temperature of 210℃, a zone temperature of 215℃, and a die head temperature of 220℃.

[0069] Comparative Example 3

[0070] This comparative example discloses one composition of polylactic acid filled with seaweed fiber and its preparation method, using the same implementation method as Example 5, except that 3.5 parts zinc borate and 68 parts seaweed fiber are replaced with 10 parts zinc borate and 61.5 parts seaweed fiber.

[0071] The specific preparation steps are as follows:

[0072] By weight, 100 parts of polylactic acid, 10 parts of zinc borate, 4 parts of γ-aminopropylsilanetriol, 2.5 parts of antioxidant, and 2 parts of lubricant butyl stearate were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 61.5 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0073] The twin-screw extruder has a zone temperature of 180℃, a zone temperature of 200℃, a zone temperature of 210℃, a zone temperature of 215℃, and a die head temperature of 220℃.

[0074] Comparative Example 4

[0075] This comparative example discloses one composition of polylactic acid filled with seaweed fiber and its preparation method, using the same implementation method as Example 5, except that 3.5 parts zinc borate and 68 parts seaweed fiber are replaced with 0.5 parts zinc borate and 71 parts seaweed fiber.

[0076] The specific preparation steps are as follows:

[0077] By weight, 100 parts of polylactic acid, 0.5 parts of zinc borate, 4 parts of γ-aminopropylsilanetriol, 2.5 parts of antioxidant, and 2 parts of lubricant butyl stearate were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 71 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0078] The twin-screw extruder has a zone temperature of 180℃, a zone temperature of 200℃, a zone temperature of 210℃, a zone temperature of 215℃, and a die head temperature of 220℃.

[0079] Comparative Example 5

[0080] This comparative example discloses one composition of polylactic acid filled with seaweed fiber and its preparation method, using the same implementation method as Example 5, except that zinc borate is replaced with an equal part by weight of antimony trioxide.

[0081] The specific preparation steps are as follows:

[0082] By weight, 100 parts of polylactic acid, 3.5 parts of antimony trioxide, 4 parts of γ-aminopropylsilanetriol, 2.5 parts of antioxidant, and 2 parts of lubricant butyl stearate were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 68 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0083] The twin-screw extruder has a zone temperature of 180℃, a zone temperature of 200℃, a zone temperature of 210℃, a zone temperature of 215℃, and a die head temperature of 220℃.

[0084] Comparative Example 6

[0085] This comparative example discloses one composition of seaweed fiber filled polylactic acid and its preparation method, using the same implementation method as Example 5, except that γ-aminopropylsilanetriol is replaced with an equal part by weight of KH550.

[0086] The specific preparation steps are as follows:

[0087] By weight, 100 parts of polylactic acid, 3.5 parts of zinc borate, 4 parts of coupling agent KH550, 2.5 parts of antioxidant, and 2 parts of lubricant butyl stearate were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 68 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0088] The twin-screw extruder has a zone temperature of 180℃, a zone temperature of 200℃, a zone temperature of 210℃, a zone temperature of 215℃, and a die head temperature of 220℃.

[0089] Comparative Example 7

[0090] This comparative example discloses one composition of polylactic acid filled with seaweed fiber and its preparation method, using the same implementation method as Example 5, except that γ-aminopropylsilanetriol is replaced with an equal part by weight of KH570.

[0091] The specific preparation steps are as follows:

[0092] By weight, 100 parts of polylactic acid, 3.5 parts of zinc borate, 4 parts of coupling agent KH570, 2.5 parts of antioxidant, and 2 parts of lubricant butyl stearate were poured into a high-speed mixer and mixed evenly. The mixture was then fed into a twin-screw extruder through the main feed port. At the same time, 68 parts of seaweed fiber were fed into the twin-screw extruder through the side feed port. The mixture was melt-extruded and granulated to obtain seaweed fiber-filled polylactic acid.

[0093] The twin-screw extruder has a zone temperature of 180℃, a zone temperature of 200℃, a zone temperature of 210℃, a zone temperature of 215℃, and a die head temperature of 220℃.

[0094] Performance testing

[0095] The polylactic acid compositions prepared in the examples and comparative examples were tested for their mechanical and flame retardant properties according to the following test schemes and standards:

[0096] Mechanical properties: Tensile strength was tested according to standard ISO 527-2.

[0097] Flame retardant performance: Referring to standard UL94, a 1.6mm thick sample was tested for vertical burning with sample dimensions of 125mm × 13mm × 5mm. The results are shown in Table 1.

[0098] Table 1. Test results of mechanical and flame retardant properties of polylactic acid compositions.

[0099] Example 1 V0 65.2 Example 2 V0 83.9 Example 3 V0 86.3 Example 4 V0 90.1 Example 5 V0 93.5 Example 6 V0 96.6 Comparative Example 1 V2 96.8 Comparative Example 2 V0 44.1 Comparative Example 3 V1 92.7 Comparative Example 4 V2 93.5 Comparative Example 5 V2 93.2 Comparative Example 6 V1 82.7 Comparative Example 7 V1 83.6

[0100] As can be seen from the test results in Table 1, the seaweed fiber filled polylactic acid provided in this invention has excellent flame retardant properties and mechanical strength.

[0101] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A type of polylactic acid-filled seaweed fiber, characterized in that, It is prepared by weight proportions of 100 parts polylactic acid, 20-100 parts seaweed fiber, 1-5 parts zinc borate, 0.5-5 parts γ-aminopropylsilanetriol, 0.5-3 parts antioxidant and 0.1-3 parts lubricant.

2. The seaweed fiber filled with polylactic acid as described in claim 1, characterized in that, The polylactic acid has a melt index of 10-30 g / 10 min and is tested at 230℃ and 2.16 kg.

3. The seaweed fiber filled with polylactic acid as described in claim 1, characterized in that, The purity of the zinc borate is ≥98%.

4. The seaweed fiber filled with polylactic acid as described in claim 1, characterized in that, The seaweed fiber is a short-cut fiber with an average fiber length of 5-30 mm.

5. The seaweed fiber-filled polylactic acid as described in claim 1, characterized in that, The lubricant is at least one of stearic acid, butyl stearate, oleamide, and ethylene bis-stearamide.

6. The seaweed fiber-filled polylactic acid as described in claim 1, characterized in that, The antioxidant is at least one of hindered phenols, thiolated compounds, hindered amines, and phosphites.

7. The seaweed fiber-filled polylactic acid as described in claim 6, characterized in that, The antioxidant is at least one of antioxidant 1076, antioxidant 1098, antioxidant 1010, antioxidant 300, or antioxidant 168.

8. The seaweed fiber-filled polylactic acid as described in claim 7, characterized in that, The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:

1.

9. A method for preparing polylactic acid filled with seaweed fiber as described in any one of claims 1-8, characterized in that, Includes the following steps: Weigh out 100 parts of polylactic acid, 20-100 parts of seaweed fiber, 1-5 parts of zinc borate, 0.5-5 parts of γ-aminopropylsilanetriol, 0.5-3 parts of antioxidant, and 0.1-3 parts of lubricant according to the following weight ratio; Polylactic acid, zinc borate, γ-aminopropylsilanetriol, antioxidant and lubricant are thoroughly mixed to obtain a uniform premix. The premixed material and seaweed fiber are fed into a twin-screw extruder through the main feed port and the side feed port, respectively, and then melt-extruded to obtain seaweed fiber-filled polylactic acid.

10. The preparation method according to claim 9, characterized in that, The twin-screw extruder has a zone temperature of 130-180℃, a zone temperature of 180-200℃, a zone temperature of 200-210℃, a zone temperature of 210-215℃, and a die head temperature of 210-220℃.