Preparation method of ultrasonic treatment modified bamboo powder polypropylene composite material

Abstract

The invention provides a preparation method of an ultrasonic treatment modified bamboo powder polypropylene composite material, and belongs to the technical field of high polymer materials, and the preparation method comprises the following steps: ultrasonic treatment of bamboo powder: taking the bamboo powder sieved by a 500-mesh sieve, sequentially soaking the bamboo powder in three medium solutions, carrying out ultrasonic treatment each time, and cleaning and drying the bamboo powder after all the treatment is completed; preparation of the composite material: mixing the dried bamboo powder with the compatilizer in proportion to obtain a component A; mixing polypropylene, a lubricant and an antioxidant in proportion to obtain a component B; uniformly mixing the component A and the component B, extruding and granulating to obtain material granules; and post-treatment: carrying out drying treatment on the cooled material particles, and removing moisture and volatile matters to obtain the composite material. According to the invention, the bamboo powder is jointly treated by ultrasonic physical and chemical aspects, the interfacial compatibility of the bamboo powder and polypropylene is synergistically improved, the treatment method is simple, and the prepared bamboo powder and polypropylene composite material has the characteristics of easy realization of industrial production and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a method for preparing ultrasonically modified bamboo powder polypropylene composite material. Background Technology

[0002] Bamboo powder is a renewable natural material with excellent biodegradability, capable of being broken down into carbon dioxide and water by microorganisms in the natural environment. This characteristic has made bamboo powder a focus of attention in the field of environmentally friendly materials.

[0003] Blending bamboo powder with plastics can improve plastic properties. Bamboo powder's high filler content enhances the mechanical properties of plastics, such as tear resistance and flexural strength, while maintaining good processability. Simultaneously, using bamboo powder as a filler can reduce the amount of plastic used, effectively reducing product weight and thus lowering production costs. Furthermore, bamboo is a fast-growing, renewable resource with a relatively low environmental impact during its growth process. Using bamboo powder as an additive helps reduce dependence on petroleum resources and lessen the environmental burden.

[0004] However, bamboo powder is a natural plant fiber with a surface rich in polar groups such as hydroxyl (-OH) and carboxyl (-COOH), making it highly hydrophilic; polypropylene (PP) is a saturated hydrocarbon polymer, which is non-polar and highly hydrophobic. When the two phases come into contact, the intermolecular forces are weak, resulting in poor interfacial compatibility. The essence of their poor compatibility lies in the mismatch of polarities and the incompatibility of their surface structures. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing ultrasonically modified bamboo powder polypropylene composite material, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing ultrasonically modified bamboo powder polypropylene composite material includes the following steps: (1) Ultrasonic treatment of bamboo powder: Take bamboo powder that has passed through a 500-mesh sieve and soak it in pure water, ethanol solution containing maleic anhydride grafted polypropylene and water solution containing silane coupling agent in sequence. Each soaking is accompanied by ultrasonic treatment. After all treatments are completed, clean the bamboo powder and dry it. (2) Preparation of composite material: The dried bamboo powder and compatibilizer are mixed in proportion to obtain component A; polypropylene, lubricant and antioxidant are mixed in proportion to obtain component B; component A and component B are mixed evenly and extruded into granules to obtain material particles; (3) Post-processing: The cooled granules are dried to remove moisture and volatiles, thus obtaining the composite material.

[0007] Preferably, in step (1), the volume of the pure aqueous solution is 10 times the mass of the bamboo powder, expressed in mL:g.

[0008] Preferably, in step (1), the volume of the ethanol solution containing maleic anhydride-grafted polypropylene is 10 times the mass of bamboo powder in mL:g, and the content of maleic anhydride-grafted polypropylene is 3%-5% of the mass of bamboo powder.

[0009] Preferably, in step (1), the volume of the aqueous solution containing the silane coupling agent is 10 times the mass of the bamboo powder in mL:g, and the content of the silane coupling agent is 0.5-1% of the mass of the bamboo powder.

[0010] Preferably, in step (1), the pH of the aqueous solution containing the silane coupling agent is 4-5.

[0011] Preferably, in step (2), the ratio of bamboo powder: polypropylene: compatibilizer: lubricant: antioxidant is (40-48): (48-56): 3: 0.3: 0.2 by mass.

[0012] Preferably, in step (1), the silane coupling agent is KH-550 or KH-560; in step (2), the compatibilizer is maleic anhydride-grafted polypropylene; the lubricant is calcium stearate or zinc stearate; the antioxidant is a composite antioxidant, preferably composed of 66.7% RIANOX 168 and 33.3% RIANOX 1010.

[0013] Preferably, in step (1), the ultrasonic treatment power is 300-600 W, the ultrasonic treatment time is 30-60 min, and after the treatment is completed, the bamboo powder is rinsed with clean water until the pH is 7-8, and then dried at 80℃ until the moisture content is ≤2%.

[0014] Preferably, in step (2), granulation is performed using a twin-screw extruder with a screw speed of 300 r / min and a heating temperature of 180-200℃; in step (3), the drying process is performed at a constant temperature of 100℃ for at least 4 hours.

[0015] The present invention also provides an ultrasonically modified bamboo powder polypropylene composite material, which is prepared by the above-described method for preparing ultrasonically modified bamboo powder polypropylene composite material.

[0016] The beneficial effects of the above-described technical solution of the present invention are as follows: This method employs three media solutions (pure aqueous solution, ethanol solution containing maleic anhydride-grafted polypropylene, and aqueous solution containing silane coupling agent) to sequentially immerse and ultrasonically treat bamboo powder, synergistically leveraging physical and chemical effects to significantly improve interfacial compatibility. The pure aqueous solution primarily utilizes ultrasonic cavitation for physical cleaning and surface roughening, removing impurities from the bamboo powder surface and increasing its specific surface area. In the ethanol solution containing maleic anhydride-grafted polypropylene, MAPP promotes penetration and chemical bonding on the bamboo powder surface through ultrasonic cavitation; the maleic anhydride groups undergo esterification with the hydroxyl groups of the bamboo powder to form covalent bonds, enhancing interfacial adhesion. In the aqueous solution containing silane coupling agent, KH-550 promotes hydrolysis and condensation with the hydroxyl groups on the bamboo powder surface through ultrasonic cavitation, forming Si-OC covalent bonds, transforming the bamboo powder surface from hydrophilic to hydrophobic, thus improving compatibility with polypropylene. The sequential treatment with these three media solutions creates a synergistic effect of physical cleaning, chemical bonding, and surface modification, significantly improving the interfacial compatibility between bamboo powder and polypropylene. Attached Figure Description

[0017] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein: Figure 1 This is a physical image of the product from Embodiment 2 of the present invention; Figure 2 This is a physical image of the product in Comparative Example 1 of the present invention. Detailed Implementation

[0018] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0019] Where specific experimental steps or conditions are not specified in the examples, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products. Example 1

[0020] A method for preparing ultrasonically modified bamboo powder polypropylene composite material includes the following steps: (1) Ultrasonic treatment of bamboo powder: Bamboo powder that has passed through a 500-mesh sieve was successively soaked in a pure aqueous solution, an ethanol solution containing maleic anhydride-grafted polypropylene (MAPP), and an aqueous solution containing a silane coupling agent for ultrasonic treatment. The solid-liquid ratio of the pure aqueous solution to the bamboo powder was 1:10 (bamboo powder mass: solution volume), and the ultrasonic parameters were 300 W for 30 min. In the ethanol solution containing MAPP, the MAPP content was 3% of the bamboo powder mass, and the ethanol solution volume was 10 times the bamboo powder mass (g:mL), with ultrasonic parameters of 300 W for 30 min. In the aqueous solution containing silane coupling agent, the silane coupling agent was KH-550, the dosage was 0.5% of the bamboo powder mass, the pH was 4.5, the aqueous solution volume was 10 times the bamboo powder mass (g:mL), and the ultrasonic parameters were 300 W for 30 min. After treatment, the bamboo powder was rinsed with water until the pH reached 7-8, and then dried at 80℃ until the moisture content was ≤2%. (2) Preparation of composite material: 40 parts of dried bamboo powder were mixed with 3 parts of MAPP to obtain component A; 56 parts of polypropylene, 0.3 parts of calcium stearate and 0.2 parts of composite antioxidant (preferred B125: composed of 66.7% RIANOX 168 and 33.3% RIANOX1010) were mixed to obtain component B; component A and component B were mixed evenly and then extruded and granulated in a twin-screw extruder at 300 rpm and 180°C to obtain granules; (3) Post-treatment: The cooled granules are dried at a constant temperature of 100℃ for more than 4 hours to remove moisture and volatiles, thus obtaining the composite material. Example 2

[0021] A method for preparing ultrasonically modified bamboo powder polypropylene composite material includes the following steps: (1) Ultrasonic treatment of bamboo powder: Bamboo powder that has passed through a 500-mesh sieve was successively soaked in pure aqueous solution, ethanol solution containing maleic anhydride-grafted polypropylene (MAPP), and aqueous solution containing silane coupling agent for ultrasonic treatment. The solid-liquid ratio of the pure aqueous solution to the bamboo powder was 1:10 (bamboo powder mass: solution volume), and the ultrasonic parameters were 300 W for 60 min. In the ethanol solution containing MAPP, the MAPP content was 3% of the bamboo powder mass, and the ethanol solution volume was 10 times the bamboo powder mass (g:mL), with ultrasonic parameters of 300 W for 60 min. In the aqueous solution containing silane coupling agent, the silane coupling agent was KH-550, the dosage was 0.5% of the bamboo powder mass, the pH was 4.5, the aqueous solution volume was 10 times the bamboo powder mass (g:mL), and the ultrasonic parameters were 300 W for 60 min. After treatment, the bamboo powder was rinsed with water until the pH reached 7-8, and then dried at 80℃ until the moisture content was ≤2%. (2) Preparation of composite material: 45 parts of dried bamboo powder were mixed with 3 parts of MAPP to obtain component A; 51 parts of polypropylene, 0.3 parts of calcium stearate and 0.2 parts of composite antioxidant (preferred B125: composed of 66.7% RIANOX 168 and 33.3% RIANOX1010) were mixed to obtain component B; component A and component B were mixed evenly and then extruded and granulated in a twin-screw extruder at 300 rpm and 180°C to obtain granules; (3) Post-treatment: The cooled granules are dried at a constant temperature of 100℃ for more than 4 hours to remove moisture and volatiles, thus obtaining the composite material. Example 3

[0022] A method for preparing ultrasonically modified bamboo powder polypropylene composite material includes the following steps: (1) Ultrasonic treatment of bamboo powder: Bamboo powder that has passed through a 500-mesh sieve was successively soaked in a pure aqueous solution, an ethanol solution containing maleic anhydride-grafted polypropylene (MAPP), and an aqueous solution containing a silane coupling agent for ultrasonic treatment. The solid-liquid ratio of the pure aqueous solution to the bamboo powder was 1:10 (bamboo powder mass: solution volume), and the ultrasonic parameters were 300 W for 30 min. In the ethanol solution containing MAPP, the MAPP content was 5% of the bamboo powder mass, and the ethanol solution volume was 10 times the bamboo powder mass (g:mL), with the ultrasonic parameters being 300 W for 30 min. In the aqueous solution containing the silane coupling agent, the silane coupling agent was KH-550, the dosage was 1% of the bamboo powder mass, the pH was 4.5, and the aqueous solution volume was 10 times the bamboo powder mass (g:mL), with the ultrasonic parameters being 300 W for 30 min. After treatment, the bamboo powder was rinsed with water until the pH reached 7-8, and then dried at 80℃ until the moisture content was ≤2%. (2) Preparation of composite material: 48 parts of dried bamboo powder were mixed with 3 parts of MAPP to obtain component A; 48 parts of polypropylene, 0.3 parts of calcium stearate and 0.2 parts of composite antioxidant (preferred B125: composed of 66.7% RIANOX 168 and 33.3% RIANOX1010) were mixed to obtain component B; component A and component B were mixed evenly and then extruded and granulated in a twin-screw extruder at 300 rpm and 180°C to obtain granules; (3) Post-treatment: The cooled granules are dried at a constant temperature of 100℃ for more than 4 hours to remove moisture and volatiles, thus obtaining the composite material. Example 4

[0023] A method for preparing ultrasonically modified bamboo powder polypropylene composite material includes the following steps: (1) Ultrasonic treatment of bamboo powder: Bamboo powder that has passed through a 500-mesh sieve was successively soaked in pure aqueous solution, ethanol solution containing maleic anhydride-grafted polypropylene (MAPP), and aqueous solution containing silane coupling agent for ultrasonic treatment. The solid-liquid ratio of the pure aqueous solution to the bamboo powder was 1:10 (bamboo powder mass: solution volume), and the ultrasonic parameters were 300 W for 30 min. In the ethanol solution containing MAPP, the MAPP content was 4% of the bamboo powder mass, and the ethanol solution volume was 10 times the bamboo powder mass (g:mL), with ultrasonic parameters of 300 W for 30 min. In the aqueous solution containing silane coupling agent, the silane coupling agent was KH-550, the dosage was 0.8% of the bamboo powder mass, the pH was 4.5, and the aqueous solution volume was 10 times the bamboo powder mass (g:mL), with ultrasonic parameters of 300 W for 30 min. After treatment, the bamboo powder was rinsed with water until the pH reached 7-8, and then dried at 80℃ until the moisture content was ≤2%. (2) Preparation of composite material: 42 parts of dried bamboo powder were mixed with 3 parts of MAPP to obtain component A; 54 parts of polypropylene, 0.3 parts of calcium stearate and 0.2 parts of composite antioxidant (preferred B125: composed of 66.7% RIANOX 168 and 33.3% RIANOX1010) were mixed to obtain component B; component A and component B were mixed evenly and then extruded and granulated in a twin-screw extruder at 300 rpm and 180°C to obtain granules; (3) Post-treatment: The cooled granules are dried at a constant temperature of 100℃ for more than 4 hours to remove moisture and volatiles, thus obtaining the composite material. Comparative Example 1

[0024] The difference between this and Example 2 is that the bamboo powder is not soaked and ultrasonically treated using pure aqueous solution, ethanol solution containing maleic anhydride grafted polypropylene, or aqueous solution containing silane coupling agent. Comparative Example 2

[0025] The difference between this and Example 2 is that, instead of using pure aqueous solution, ethanol solution containing maleic anhydride grafted polypropylene, and aqueous solution containing silane coupling agent to soak and ultrasonically treat bamboo powder, bamboo powder is soaked in a 1% (w / w) NaOH solution with a ratio of bamboo powder to NaOH solution of 1:10 (g:mL) and ultrasonic treatment parameters of 300 W for 60 min. Comparative Example 3

[0026] The difference between this and Example 2 is that only bamboo powder is soaked in pure aqueous solution for ultrasonic treatment, without using ethanol solution containing compatibilizer and aqueous solution containing silane coupling agent. Comparative Example 4

[0027] The difference between this and Example 2 is that only bamboo powder is soaked in an ethanol solution containing a compatibilizer and then subjected to ultrasonic treatment, without using pure aqueous solution or aqueous solution containing silane coupling agent. Comparative Example 5

[0028] The difference between this and Example 2 is that only bamboo powder is soaked in an aqueous solution containing a silane coupling agent and then ultrasonically treated, without using pure aqueous solution and ethanol solution containing MAPP. Comparative Example 6

[0029] The difference between this and Example 2 is that the ratio of the extruded material is bamboo powder: polypropylene: compatibilizer: lubricant: antioxidant = 30:67:3:0.3:0.2.

[0030] The composite materials of Examples 1-4 and Comparative Examples 1-6 were prepared into standard test specimens by injection molding and their performance was tested. The results are shown in the table below.

[0031] Test standards: Tensile strength is tested according to GB / T 1040.2-2006, flexural strength is tested according to GB / T 9341-2008, and impact strength is tested according to GB / T 1843-2008.

[0032] Performance indicators Tensile strength (MPa) Flexural strength MPa <![CDATA[Impact strength KJ / m 2 > Example 1 29.5 36.5 3.9 Example 2 35.5 42.1 4.5 Example 3 31.2 39.0 3.7 Example 4 29.1 36.2 3.5 Comparative Example 1 23.0 30.1 2.8 Comparative Example 2 25.5 32.0 3.1 Comparative Example 3 24.3 31.5 2.9 Comparative Example 4 28.2 35.0 3.7 Comparative Example 5 25.6 32.5 3.3 Comparative Example 6 26.1 33.2 3.5 From the data in the table and Figure 1 and Figure 2 The comparison shows that: Examples 1-4 all outperformed Comparative Examples 1-6, with Example 2 exhibiting the best overall mechanical properties, including a tensile strength of 35.5 MPa, a flexural strength of 42.1 MPa, and an impact strength of 4.5 kJ / m. 2 Compared to Comparative Example 1, which did not undergo any media treatment on the bamboo powder, the performance improvement was significant. Compared to Comparative Example 2, which used traditional alkali treatment, the performance advantage of Example 2 of this invention remained very significant. Image comparison shows that the particles in Example 2 have uniform morphology, moderate surface color, and consistent hue, while those in Comparative Example 1 have rough morphology, weak gloss, and a darker, uneven color. This indicates that the three-step ultrasonic treatment process proposed in this invention—from pure water ultrasonic cleaning to chemical bonding with MAPP ethanol solution, and then to hydrophobic modification with silane aqueous solution—has a significant synergistic enhancement effect. Analysis of the data from Comparative Examples 3-5 shows that the absence of any step in this three-step process leads to incomplete interface modification, thus limiting the improvement of the final composite material's performance.

[0033] Comparative Example 3 (pure water treatment only) only had physical cleaning and roughening effects, lacking chemical bonding and surface polarity regulation; Comparative Example 4 (MAPP treatment only) could establish partial chemical bonding, but the bamboo powder surface remained hydrophilic, resulting in insufficient compatibility with the polypropylene matrix; Comparative Example 5 (silane treatment only) could change the surface polarity, but lacked a strong interfacial chemical bonding bridge. Combining the three treatments organically achieves physical cleaning, chemical bonding, and surface hydrophobicity sequentially. Promoted by the ultrasonic cavitation effect, a firmly bonded and highly compatible bamboo powder-polypropylene interface is ultimately constructed. Furthermore, the performance of Comparative Example 6 (30 parts bamboo powder) was lower than that of the embodiments within the preferred ratio range of this invention, indicating that the bamboo powder filling ratio (the proportion of each component) also has a crucial impact on the performance of the produced composite material.

[0034] In summary, the method for preparing ultrasonically modified bamboo powder polypropylene composite material provided by this invention effectively solves the key technical problem of poor interfacial compatibility between bamboo powder and polypropylene through the synergistic effect of multi-step media solutions (pure aqueous solution, ethanol solution containing maleic anhydride grafted polypropylene, and aqueous solution containing silane coupling agent) and ultrasonic treatment. This method features clear process steps, controllable parameters, and significant effects. The prepared composite material exhibits excellent mechanical properties and environmentally friendly characteristics, demonstrating promising prospects for industrial application.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing ultrasonically modified bamboo powder polypropylene composite material, characterized in that, Includes the following steps: (1) Ultrasonic treatment of bamboo powder: Take bamboo powder that has passed through a 500-mesh sieve and soak it in pure water, ethanol solution containing maleic anhydride grafted polypropylene and aqueous solution containing silane coupling agent in sequence. Each soaking is accompanied by ultrasonic treatment. After all treatments are completed, clean the bamboo powder and dry it. (2) Preparation of composite material: The dried bamboo powder and compatibilizer are mixed in proportion to obtain component A; polypropylene, lubricant and antioxidant are mixed in proportion to obtain component B; component A and component B are mixed evenly and extruded into granules to obtain granules; (3) Post-processing: The cooled granules are dried to remove moisture and volatiles, thus obtaining the composite material.

2. The method for preparing ultrasonically modified bamboo powder polypropylene composite material according to claim 1, characterized in that, In step (1), the volume of the pure aqueous solution is 10 times the mass of the bamboo powder, expressed in mL:g.

3. The method for preparing ultrasonically modified bamboo powder polypropylene composite material according to claim 1, characterized in that, In step (1), the volume of the ethanol solution containing maleic anhydride-grafted polypropylene is 10 times the mass of bamboo powder (mL:g), and the content of maleic anhydride-grafted polypropylene is 3%-5% of the mass of bamboo powder.

4. The method for preparing ultrasonically modified bamboo powder polypropylene composite material according to claim 1, characterized in that, In step (1), the volume of the aqueous solution containing silane coupling agent is 10 times the mass of bamboo powder in mL:g, and the content of silane coupling agent is 0.5-1% of the mass of bamboo powder.

5. The method for preparing ultrasonically modified bamboo powder polypropylene composite material according to claim 1, characterized in that, In step (1), the pH of the aqueous solution containing the silane coupling agent is 4-5.

6. The method for preparing ultrasonically modified bamboo powder polypropylene composite material according to claim 1, characterized in that, In step (2), the mass ratio of bamboo powder:polypropylene:composite agent:lubricant:antioxidant = (40-48):(48-56): 3：0.3：0.2。 7. The method for preparing ultrasonically modified bamboo powder polypropylene composite material according to claim 1, characterized in that, In step (1), the silane coupling agent is KH-550 or KH-560; in step (2), the compatibilizer is maleic anhydride-grafted polypropylene; the lubricant is calcium stearate or zinc stearate; the antioxidant is a composite antioxidant, preferably composed of 66.7% RIANOX 168 and 33.3% RIANOX 1010.

8. The method for preparing ultrasonically modified bamboo powder polypropylene composite material according to claim 1, characterized in that, In step (1), the ultrasonic treatment power is 300-600 W, and the ultrasonic treatment time is 30-60 min each time. After the treatment is completed, the bamboo powder is rinsed with clean water until the pH is 7-8, and then dried at 80℃ until the moisture content is ≤2%.

9. The method for preparing ultrasonically modified bamboo powder polypropylene composite material according to claim 1, characterized in that, In step (2), the granulation is performed by extrusion using a twin-screw extruder with a screw speed of 300 r / min and a heating temperature of 180-200℃; in step (3), the drying process is performed by constant temperature drying at 100℃ for more than 4 hours.

10. Ultrasonic-treated modified bamboo powder polypropylene composite material prepared by the preparation method of ultrasonic-treated modified bamboo powder polypropylene composite material according to any one of claims 1-9.

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