High-strength material prepared from recycled PP

Abstract

The invention relates to the technical field of high-strength materials, and discloses a high-strength material prepared from recycled PP. The high-strength material comprises the following components: recycled PP; a bio-based polymer; a supramolecular polymer; a functionalized filler; a compatibility auxiliary agent; the invention further provides a preparation process of the high-strength material prepared from the recycled PP. The cleaned recycled polypropylene is selected; primarily mixing the recycled PP and the bio-based polymer by using a high-temperature melt extrusion method; adding a supramolecular polymer and a functionalized filler to the primary mixture; adding a compatibility auxiliary agent into the secondary mixture; a dynamic cross-linking agent is added during final mixing; and the final mixture is injection-molded through a mold. By adopting the technical scheme of compounding the high-proportion recycled polypropylene and the bio-based polymer, the excellent mechanical property of the material is achieved, and the problem that the performance of a traditional material is not ideal under the occasion of high-strength requirements is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-strength materials, and in particular to a high-strength material made from recycled PP. Background Art

[0002] Plastics are currently widely used across various industries, particularly in areas with high strength requirements, such as power systems. Traditional plastic materials, such as polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC), have dominated the market due to their superior cost and performance. However, the limitations of single materials in improving both strength and toughness are becoming increasingly apparent, often failing to meet the dual performance demands of modern applications.

[0003] First, existing plastic materials often lack sufficient strength and impact resistance. While traditional polypropylene offers good rigidity, it exhibits a certain degree of brittleness under high stress conditions, which can lead to unexpected breakage in practical applications. Furthermore, polypropylene alone lacks sufficient tensile strength and fracture toughness, easily leading to material failure. Therefore, it is necessary to explore new material solutions by combining different polymer types to enhance overall performance.

[0004] Secondly, many existing materials are not environmentally friendly enough. Most existing plastics are derived from petrochemicals, and their production and disposal processes result in significant environmental pollution and resource waste. While some bio-based materials have emerged on the market, these often lack the strength and processing properties required for stringent industrial applications.

[0005] Furthermore, the processing properties of existing materials often present a bottleneck. Many polymers exhibit poor melt flow, resulting in poor flow during injection molding and molding, which in turn affects production efficiency. This not only increases production costs but can also compromise the quality of the final product. Therefore, optimizing material melt flowability has become a pressing issue. Summary of the Invention

[0006] The purpose of the present invention is to provide a high-strength material made of recycled PP, which solves the problems of traditional plastics in terms of strength, toughness and environmental protection.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: A high-strength material made of recycled PP, comprising the following components by weight: 70-80 parts of recycled polypropylene; 10-20 parts of bio-based polymer; 5-10 parts of supramolecular polymer; 1-5 parts of functional filler; 1-3 parts of compatibility additive; Dynamic crosslinking agent 0.5 parts to 3 parts.

[0008] Preferably, the bio-based polymer is polylactic acid, the supramolecular polymer is polyvinyl alcohol, and the molecular weight of the polyvinyl alcohol is in the range of 50,000-100,000.

[0009] Furthermore, polylactic acid is not only a polymer material with good biocompatibility and biodegradability, but also has good compatibility with recycled polypropylene. At the same time, the added supramolecular polymer helps to enhance the overall toughness and impact resistance of the material.

[0010] Preferably, the functionalized filler is functionalized graphene, and the graphene is functionalized by chemical vapor deposition.

[0011] Furthermore, the introduction of functional fillers significantly improved the strength and stiffness of the composite material, enhancing its performance in strength and durability.

[0012] Preferably, the compatibility aid is polycaprolactone, and the dynamic cross-linking agent is cyclohexyl isocyanate.

[0013] Furthermore, the addition of compatibility additives and dynamic cross-linking agents further optimizes the dispersibility and cross-linking degree of the polymer, allowing the material to exhibit even better performance during processing and use.

[0014] A process for preparing a high-strength material made from recycled PP comprises the following steps: Selecting cleaned recycled polypropylene, performing functional treatment on the functional filler to obtain surface-active functional filler; Primary mixing of the recycled PP and the bio-based polymer is performed using a high temperature melt extrusion method to obtain a primary mixture; adding a supramolecular polymer and a functionalized filler to the primary mixture for secondary mixing to obtain a secondary mixture; Adding compatibility aid to the secondary mixture and performing final mixing; During the final mixing, a dynamic crosslinking agent is added, and a crosslinking treatment is performed at a temperature of 190° C. to 220° C. for 3 minutes to obtain a final mixture; The final mixture is injection molded through a mold at a temperature of 60°C-80°C for 1-2 hours.

[0015] Furthermore, the process includes selecting washed recycled polypropylene, functionalizing a functional filler, performing primary mixing of the recycled PP and a bio-based polymer using a high-temperature melt extrusion method, adding a supramolecular polymer and a functional filler to the primary mixture for secondary mixing, adding a compatibility aid for final mixing, and adding a dynamic cross-linking agent for cross-linking during the final mixing.

[0016] Preferably, the temperature of the primary mixing is controlled at 180° C.-220° C., the rotation speed is 150-300 rpm, and the mixing time is 3-5 minutes.

[0017] Preferably, the functionalization treatment of the functionalized filler is performed by chemical vapor deposition at a temperature of 600° C.-800° C. for 1 hour.

[0018] Preferably, the secondary mixing temperature is controlled at 190° C.-210° C., the rotation speed is 150-300 rpm, and the mixing time is 2-4 minutes.

[0019] Preferably, the final mixing temperature is maintained at 190° C.-210° C., the rotation speed is 150-300 rpm, and the mixing time is 2 minutes.

[0020] Preferably, the temperature of the mold for injection molding is controlled at 20° C.-60° C., and the applied pressure is 30-60 MPa.

[0021] In summary, the present invention includes at least one of the following beneficial technical effects: 1. This invention achieves excellent mechanical properties by combining a high proportion of recycled polypropylene with a bio-based polymer. Compared to existing technologies using a single polymer, this composite solution significantly improves tensile strength and fracture toughness, resolving the issue of traditional materials' suboptimal performance in high-strength applications.

[0022] 2. This invention utilizes functionalized fillers to enhance the structural integrity of the material, creating a composite material that combines high strength and toughness. This differs from commonly used filler methods and significantly improves the material's performance under high stress, avoiding the common brittle fracture phenomenon and addressing the rapid degradation of traditional composite materials.

[0023] 3. This invention improves melt fluidity by optimizing the processing technology, allowing the material to flow more smoothly during the injection and molding process. Compared with existing high-temperature processing technologies, this design concept reduces energy consumption and waste during the production process, and solves the problem of high production difficulty caused by the traditional process's lack of attention to fluidity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the method of the present invention. DETAILED DESCRIPTION

[0025] The following is combined with Figure 1 , the present invention is described in further detail.

[0026] like Figure 1 As shown, the present invention provides a high-strength material made from recycled PP: Example 1 Material formula: Recycled polypropylene (PP): 75 parts Bio-based polymer (polylactic acid): 15 parts Supramolecular polymer (polyvinyl alcohol): 7 parts Functionalized filler (functionalized graphene): 3 parts Compatibility additive (polycaprolactone): 2 parts Dynamic crosslinking agent (cyclohexyl isocyanate): 1.5 parts Preparation steps: Raw material preparation: Select cleaned and dried recycled polypropylene, polylactic acid, polyvinyl alcohol and other additives, and ensure that the dryness of the material is below 2%.

[0027] The functionalized graphene was treated by chemical vapor deposition with the temperature set at 700 °C for 1 hour to ensure its surface activity.

[0028] The temperature was set at 200° C. and the rotation speed was set at 250 rpm in a high-temperature melt extruder, and the recycled PP and polylactic acid were preliminarily mixed for 4 minutes to obtain a uniform preliminarily mixed mixture.

[0029] Polyvinyl alcohol and functionalized graphene were gradually added to the primary mixture, and the mixing was continued while maintaining the temperature at 205° C., the rotation speed at 250 rpm, and the mixing time for 3 minutes to obtain a secondary mixture.

[0030] A compatibility aid and a dynamic cross-linking agent were added to the secondary mixture, and final mixing was performed with the temperature controlled at 200° C., the rotation speed at 250 rpm, and the mixing time at 2 minutes to obtain a final mixture.

[0031] The final mixture was injection molded with the mold temperature set at 50 °C, the applied pressure at 40 MPa, the molding time at 1.5 h, and cooled to room temperature.

[0032] Example 2 Material formula: Recycled polypropylene (PP): 70 parts Bio-based polymer (polylactic acid): 10 parts Supramolecular polymer (polyvinyl alcohol): 5 parts Functionalized filler (functionalized graphene): 1 part Compatibility additive (polycaprolactone): 1 part Dynamic crosslinking agent (cyclohexyl isocyanate): 0.5 parts Preparation steps: Raw material preparation: Prepare the recycled polypropylene, polylactic acid, polyvinyl alcohol and other materials after cleaning and drying, and control the dryness below 2%.

[0033] The functionalized graphene was treated by chemical vapor deposition at a temperature of 600°C for 1 hour to ensure a suitable functionalization effect.

[0034] The temperature was set at 180° C. and the rotation speed was set at 150 rpm in the high-temperature melt extruder, and the recycled PP and polylactic acid were preliminarily mixed for 3 minutes to form a primary mixture.

[0035] Polyvinyl alcohol and functionalized graphene were added to the primary mixture, and mixing was continued at 180° C., a rotation speed of 150 rpm, and a mixing time of 2 minutes to form a secondary mixture.

[0036] A compatibility aid and a dynamic cross-linking agent were added for final mixing, with the temperature maintained at 180° C., the rotation speed at 150 rpm, and the mixing time being 1.5 minutes to obtain a final mixture.

[0037] The final mixture was injection molded with the mold temperature set at 20°C, the applied pressure at 30 MPa, and the molding time at 1 hour, after which it was cooled to room temperature.

[0038] Example 3 Material formula: Recycled polypropylene (PP): 80 parts Bio-based polymer (polylactic acid): 20 parts Supramolecular polymer (polyvinyl alcohol, PVA): 10 parts Functionalized filler (functionalized graphene): 5 parts Compatibility additive (polycaprolactone): 3 parts Dynamic crosslinking agent (cyclohexyl isocyanate): 3 parts Preparation steps: Raw material preparation: Prepare cleaned recycled polypropylene, polylactic acid, polyvinyl alcohol and other materials, and ensure that the dryness of the material is less than 2%.

[0039] The functionalized graphene was subjected to chemical vapor deposition treatment with the treatment temperature set at 800 °C for 1 hour to ensure efficient functionalization.

[0040] The temperature was set at 220° C. and the rotation speed was set at 300 rpm in a high-temperature melt extruder, and the recycled PP and polylactic acid were preliminarily mixed for 5 minutes to obtain a uniform preliminarily mixed mixture.

[0041] Polyvinyl alcohol and functionalized graphene were added to the primary mixture and the mixture was mixed continuously with the temperature set at 210°C, the rotation speed at 300 rpm and the mixing time at 4 minutes to form a secondary mixture.

[0042] A compatibility aid and a dynamic cross-linking agent were added to the secondary mixture for final mixing. The temperature was maintained at 210° C., the rotation speed was 300 rpm, and the mixing time was continued for 2 minutes to obtain a final mixture.

[0043] The final mixture was injection molded through a mold with the mold temperature set at 60 °C, an applied pressure of 60 MPa, and a molding time of 2 h, followed by cooling to room temperature.

[0044] Comparative Example 1: Compared with Example 1, the difference is that polylactic acid is not used, and the rest are the same.

[0045] Comparative Example 2: Compared with Example 1, the difference is that functionalized graphene is not used, and the rest are the same.

[0046] Comparative Example 3: Compared with Example 1, the difference is that the temperature of the primary mixing is lowered to 180°C, and the rest are the same.

[0047] Experiment 1: Mechanical properties test Experimental Description Purpose: To evaluate the differences in mechanical properties between Example 1 and Comparative Example 1 under tension and impact.

[0048] Materials and equipment Material samples prepared in Example 1 and Comparative Example 1 Tensile testing machine Impact testing machine (cantilever beam type) Standard laboratory temperature and humidity control equipment electronic balance Environmental chamber (control temperature and humidity) Sample preparation: The material samples of Example 1 and Comparative Example 1 were cut into the same size according to the standard (eg, the tensile specimen was 100 mm long, 10 mm wide, and 1 mm thick, and the impact specimen was 80 mm long, 10 mm wide, and 4 mm thick).

[0049] Place the samples in a constant temperature and humidity chamber for 24 h to ensure that the samples adapt to the experimental environment, with a temperature of 23 ± 2 °C and a humidity of 50 ± 5%.

[0050] Using a tensile testing machine, a tensile load was applied to each sample.

[0051] The maximum load-bearing capacity and displacement at fracture were recorded, and the tensile strength was calculated.

[0052] The Izod impact test was performed on an impact testing machine.

[0053] Use an impact hammer of the same weight to apply the same impact energy to each sample, and record the sample breakage and absorbed impact energy.

[0054] The results of each test were recorded in a data sheet and the experiment was repeated at least three times to ensure the reliability of the data.

[0055] The collected data were analyzed, the average value and standard deviation were calculated, and the mechanical properties of the examples and the comparative examples were compared.

[0056] The experimental data are shown in Table 1; Table 1: Mechanical properties test results data table sample Maximum tensile strength (MPa) Fracture displacement (mm) Impact energy absorption (J) Example 1 28.5 5.2 12.3 Comparative Example 1 22.7 3.6 9.5 Example 1 29 5 13.1 Comparative Example 1 21.8 3.8 8.9 Example 1 27.9 5.5 12.5 Comparative Example 1 23.1 3.4 9.1 Summarize; In this experiment, the material of Example 1 exhibited excellent mechanical properties, mainly due to its unique combination of components and interaction mechanism. By combining a high proportion of recycled polypropylene with polylactic acid, a composite material with excellent mechanical properties was formed. The flexibility of polylactic acid and the high strength of recycled polypropylene complement each other, effectively improving the tensile strength and fracture toughness of the material. In tensile and impact tests, Example 1 demonstrated higher tensile strength and better impact energy absorption capacity than Comparative Example 1, indicating that the combination of the two polymers effectively improves the overall performance of the material.

[0057] The functionalized filler (functionalized graphene) used in the experiment further enhances the surface characteristics and structural integrity of the material. The introduction of functionalized graphene improves the load-distributing ability and interfacial bonding force of the material, prevents the polymer chain fracture under high stress. This synergistic effect makes Example 1 more elastic and stable when subjected to external force, and the energy absorption in the impact process is more effective, reduces the brittleness of the material, and improves its impact resistance. This is closely related to the crosslinking degree and interfacial compatibility of polymer, and also emphasizes the necessity of utilizing functionalized filler.

[0058] The results obtained in this experiment emphasize the importance of optimizing composite material properties by adjusting material formulation and selecting appropriate processing technology. For Example 1, the appropriate primary mixing temperature and the use of dynamic crosslinking ensured good compatibility between polymers, thereby achieving optimal physical properties.

[0059] Experiment 2: Thermal stability test Experimental Description Purpose: To evaluate the thermal stability of Example 1 and Comparative Example 2 under high temperature conditions and to determine the thermal properties of the materials by comparing their thermal decomposition temperatures and residual masses.

[0060] Materials and equipment Material samples prepared in Example 1 and Comparative Example 2 Thermogravimetric Analyzer (TGA) Nitrogen atmosphere and air atmosphere delivery system electronic balance Data logging and analysis software Sample preparation: The material samples of Example 1 and Comparative Example 2 were cut into small pieces of about 5 mg, and the amount of each sample was kept consistent to ensure the comparability of the experiments.

[0061] Start the thermogravimetric analyzer, select the appropriate atmosphere (nitrogen or air), and calibrate the instrument according to the manufacturer's instructions.

[0062] Set the temperature range of the thermogravimetric analyzer from room temperature to 600°C and select a heating rate (e.g., 10°C / min) according to experimental requirements.

[0063] Each sample was placed in a sample tray and placed in the test chamber of the thermogravimetric analyzer.

[0064] Start testing and record the mass change and decomposition process of the material at different temperatures, paying particular attention to key temperature points (such as the temperatures corresponding to 10% mass loss and 50% mass loss).

[0065] During the test, the software automatically records the mass data and observes the thermal curve (thermogravimetric curve).

[0066] After the test, the thermogravimetric analysis data was processed using software to obtain the thermal decomposition temperature and residual mass of the material, and a comparative analysis was performed.

[0067] The experimental data are shown in Table 2; Table 2: Thermal stability test results data table Summarize; In this experiment, the material of Example 1 showed excellent thermal stability, mainly due to its complex polymer combination and interaction mechanism. By compounding a high proportion of recycled polypropylene with polylactic acid, the thermal stability of the material was significantly improved. The thermal degradation characteristics of polylactic acid combined with the heat resistance of recycled polypropylene formed a composite material with even better thermal performance, which can effectively suppress mass loss during thermal decomposition. This shows that the interaction and compatibility of the polymer chains in the material play a key role under high temperature conditions.

[0068] The functionalized filler (functionalized graphene), not used in the experiment, also played a positive role in thermal stability. By enhancing load dispersion within the polymer matrix, functionalized graphene improves the material's thermal conductivity and heat dissipation capacity, thereby slowing the accumulation of thermal stress and reducing the rate of decomposition reactions. In contrast, Comparative Example 2 lacks these functionalized components, resulting in poor thermal stability. The temperature at which mass loss occurs during thermal degradation is significantly lower, indicating increased brittleness and poorer thermal stress tolerance.

[0069] Experiment 3: Processing performance test Experimental Description Purpose: To evaluate the melt flowability of Example 1 and Comparative Example 3 during processing to determine the processing performance of the materials.

[0070] Materials and equipment Material samples prepared in Example 1 and Comparative Example 3 Melt Flow Rate Tester (MFR Tester) electronic balance Standard test mold (e.g., a cylindrical mold with a diameter of 2.095 mm) Heating furnace or hot plate Sample preparation: The material samples of Example 1 and Comparative Example 3 were cut into small pieces of about 5 grams that met the MFR test requirements.

[0071] Start the melt flow rate tester and preheat it to the set temperature (such as 230°C). Ensure that the instrument works stably and reaches the preset temperature.

[0072] Use an electronic balance to weigh 5 grams of sample and record the exact weight on the balance.

[0073] Place the weighed material sample into the test mold, ensuring that the sample is evenly distributed.

[0074] Start the melt flow rate tester to record the melt flow time of the material through the standard mold at the specified temperature, and automatically record the mass of the molten plastic flowing out.

[0075] During the test, the melt flow rate was observed and recorded, and each sample was tested three times to improve the accuracy of the data.

[0076] The collected melt flow rate data were statistically analyzed, and the average value of each sample was calculated and compared.

[0077] The experimental data are shown in Table 3; Table 3: Processing performance test results data table Summarize; In this experiment, Example 1 demonstrated excellent melt flow properties, primarily due to the good compatibility between the polymers and the addition of functionalized fillers. By compounding a high proportion of recycled polypropylene with polylactic acid, the material's fluidity was significantly improved. The combination of polylactic acid's low melting temperature and polypropylene's excellent fluidity resulted in the composite material exhibiting improved fluidity during processing, reducing viscosity during the melt process. This improved fluidity helps improve processing efficiency and ensures the material's operability in processes such as injection molding and extrusion.

[0078] Functionalized fillers (functionalized graphene), not used in the experiment, also play an important role in improving melt flow. The addition of functionalized graphene significantly enhances the mechanical properties of the polymer matrix, promoting the sliding and flow of the material molecules, thereby achieving better flowability under high temperature conditions. In contrast, Comparative Example 3, due to the use of a lower primary mixing temperature, lacks effective promotion of interaction and flowability between the polymers, resulting in decreased flowability and a melt flow rate significantly lower than that of Example 1.

[0079] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high-strength material made from recycled PP, characterized in that: The following components are included in the servings: 70-80 parts of recycled polypropylene; 10-20 parts of bio-based polymer; 5-10 parts of supramolecular polymer; 1-5 parts of functional filler; 1-3 parts of compatibility additive; Dynamic crosslinking agent 0.5 parts to 3 parts.

2. The high-strength material made of recycled PP according to claim 1, characterized in that: The bio-based polymer is polylactic acid, the supramolecular polymer is polyvinyl alcohol, and the molecular weight of the polyvinyl alcohol is in the range of 50,000-100,000.

3. The high-strength material made of recycled PP according to claim 1, characterized in that: The functionalized filler is functionalized graphene, and the graphene is functionalized by chemical vapor deposition.

4. The high-strength material made of recycled PP according to claim 1, characterized in that: The compatibility aid is polycaprolactone, and the dynamic cross-linking agent is cyclohexyl isocyanate.

5. A process for preparing a high-strength material made from recycled PP, for preparing a high-strength material made from recycled PP as claimed in any one of claims 1 to 4, characterized in that: The following steps are included: Selecting cleaned recycled polypropylene, performing functional treatment on the functional filler to obtain surface-active functional filler; Primary mixing of the recycled PP and the bio-based polymer is performed using a high temperature melt extrusion method to obtain a primary mixture; adding a supramolecular polymer and a functionalized filler to the primary mixture for secondary mixing to obtain a secondary mixture; Adding compatibility aid to the secondary mixture and performing final mixing; During the final mixing, a dynamic crosslinking agent is added, and a crosslinking treatment is performed at a temperature of 190° C. to 220° C. for 3 minutes to obtain a final mixture; The final mixture is injection molded through a mold at a temperature of 60°C-80°C for 1-2 hours.

6. The process for preparing high-strength materials made from recycled PP according to claim 5, characterized in that: The temperature of the primary mixing is controlled at 180° C.-220° C., the rotation speed is 150-300 rpm, and the mixing time is 3-5 minutes.

7. The process for preparing high-strength materials made from recycled PP according to claim 5, characterized in that: The functionalization treatment of the functionalized filler is carried out by chemical vapor deposition, with a temperature of 600° C.-800° C. and a treatment time of 1 hour.

8. The process for preparing high-strength materials made from recycled PP according to claim 5, characterized in that: The secondary mixing temperature is controlled at 190° C.-210° C., the rotation speed is 150-300 rpm, and the mixing time is 2-4 minutes.

9. The process for preparing high-strength material made from recycled PP according to claim 5, characterized in that: The final mixing temperature was maintained at 190° C.-210° C., the rotation speed was 150-300 rpm, and the mixing time was 2 minutes.

10. The process for preparing high-strength materials made from recycled PP according to claim 5, characterized in that: The temperature of the mold for injection molding is controlled at 20° C.-60° C., and the applied pressure is 30-60 MPa.

Images