Wollastonite fiber reinforced polyvinyl chloride composite material as well as preparation method and application thereof

Abstract

The invention provides a wollastonite fiber reinforced polyvinyl chloride composite material as well as a preparation method and application thereof, and relates to the technical field of polymer composites.The preparation method comprises the steps that wollastonite fibers are subjected to weak acid etching treatment to form modified wollastonite fibers, an oxalic acid-citric acid mixed solution is adopted for weak acid etching treatment, the surface of the modified wollastonite fiber is of a micro-nano dual-scale rough structure. Polyvinyl chloride resin, a heat stabilizer, a plasticizer and a lubricant are subjected to high-speed mixing treatment to form a dry blend, and a high-speed mixer is adopted for high-speed mixing treatment. According to the wollastonite fiber reinforced polyvinyl chloride composite material as well as the preparation method and the application thereof, wollastonite fibers are subjected to weak acid etching treatment to form modified fibers, and high strength and high impact resistance of the material are realized by combining the processes of high-speed mixing, sectional cooling, melt blending and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to wollastonite fiber reinforced polyvinyl chloride composite materials, their preparation methods, and applications. Background Technology

[0002] Polyvinyl chloride (PVC) resin, as a major general-purpose plastic, possesses excellent corrosion resistance, flame retardancy, and low cost, making it widely used in construction, pipe manufacturing, and packaging. To improve the rigidity, strength, and thermal stability of PVC materials, the industry commonly employs the addition of inorganic fillers for reinforcement and modification. Calcium carbonate is one of the most commonly used fillers; its addition can improve the material's modulus and hardness to a certain extent, effectively reducing raw material costs. Glass fiber is also used in the preparation of high-performance PVC composites, significantly improving the material's tensile strength and heat deformation resistance. These constitute the main technical means for the current reinforcement and modification of PVC.

[0003] Existing reinforcement technologies have significant limitations. While calcium carbonate fillers are low-cost, their increased rigidity often leads to a significant decrease in material toughness and impact strength, making the product more susceptible to brittle fracture under stress. Glass fiber reinforcement faces the problem of poor compatibility with PVC matrix; weak interfacial bonding affects stress transfer, reduces reinforcement efficiency, and glass fiber production is energy-intensive, causing significant equipment wear during processing and resulting in poor environmental performance. These limitations restrict the application of PVC composites in applications requiring higher performance, particularly in fields demanding a balance of high rigidity, high toughness, and good dimensional stability, where existing technologies struggle to meet the requirements. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides wollastonite fiber-reinforced polyvinyl chloride composite materials, their preparation methods, and applications. The technical problem this invention aims to solve is to address the issues of reduced toughness and poor glass fiber reinforcement caused by traditional filler materials by modifying wollastonite fiber-reinforced polyvinyl chloride composite materials.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a wollastonite fiber-reinforced polyvinyl chloride composite material, comprising the following components by mass percentage:

[0006] Polyvinyl chloride resin: 50%-75%;

[0007] Wollastonite fiber: 8%-22%;

[0008] Heat stabilizer: 2%-4.5%;

[0009] Plasticizer: 3%-11%;

[0010] Impact modifier: 3%-7.5%;

[0011] Titanate coupling agent: 0.3%-1.1%;

[0012] Lubricant: 0.3%-1.1%;

[0013] Processing aids: 0.7%-2.2%.

[0014] Preferably, the wollastonite fiber has a needle-like structure, the aspect ratio of the wollastonite fiber is 8:1-10:1, the whiteness of the wollastonite fiber is >82%, the fiber diameter is 14μm-16μm, the heat stabilizer is a calcium-zinc compound, the plasticizer is diphenyl phosphate, and the lubricant is polyethylene wax.

[0015] A method for preparing wollastonite fiber-reinforced polyvinyl chloride composite materials includes:

[0016] S1. Wollastonite fibers are subjected to weak acid etching treatment to form modified wollastonite fibers. The weak acid etching treatment uses a mixed solution of oxalic acid and citric acid. The surface of the modified wollastonite fibers has a micro-nano dual-scale rough structure.

[0017] S2. Polyvinyl chloride resin, heat stabilizer, plasticizer and lubricant are subjected to high-speed mixing to form a dry mixture, wherein the high-speed mixing is performed using a high-speed mixer;

[0018] S3. The dry mixture is cooled to form a cooled mixture. The cooling process is controlled by segmented cooling and is performed using a cold mixer.

[0019] S4. The modified wollastonite fiber and the cooled mixture are melt-blended to form a composite material melt, wherein the melt-blending process is performed using a twin-screw extruder;

[0020] S5. The composite material melt is subjected to extrusion granulation to form wollastonite fiber-reinforced polyvinyl chloride composite material particles.

[0021] Preferably, the oxalic acid-citric acid mixed solution comprises oxalic acid and citric acid, the mass ratio of oxalic acid to citric acid is 1:1-1:5, the weak acid etching treatment is performed at a temperature of 60℃-80℃ for a time of 15 minutes-30 minutes, and the modified wollastonite fiber is dried at 80℃.

[0022] Preferably, the high-speed mixer operates at a speed of 800 rpm to 1200 rpm, and the high-speed mixing process takes 8 to 15 minutes and is carried out at a temperature of 110°C.

[0023] Preferably, the refrigeration mixer uses circulating cooling water, and the segmented cooling control includes a rapid initial cooling stage, a medium cooling stage, and a stable cooling stage. The cooling process involves the following steps:

[0024] S31. In the rapid initial cooling stage, the dry mixture is cooled to 50°C to form an initial mixture, and the cooling rate of the rapid initial cooling stage is 10°C / min;

[0025] S32. In the intermediate cooling stage, the temperature of the initial mixture is reduced to 35°C to form a room temperature mixture, and the cooling rate of the intermediate cooling stage is 5°C / min;

[0026] S33. In the stable cooling stage, the temperature of the room temperature mixture is controlled below 30°C to form the cooled mixture, and the cooling rate of the stable cooling stage is 3°C / min.

[0027] Preferably, the melt blending treatment includes adding an impact modifier, a titanate coupling agent, and a processing aid. The extrusion temperature of the twin-screw extruder is 160℃-170℃, and the screw speed is 150rpm-180rpm. The twin-screw extruder is provided with a first temperature control zone, a second temperature control zone, a third temperature control zone, a fourth temperature control zone, and a die head area. The twin-screw extruder includes a main feed port and a side feed port. The main feed port is located at the beginning of the first temperature control zone, and the cooled mixture is added through the main feed port. The side feed port is located at the beginning of the third temperature control zone, and the modified wollastonite fiber is added through the side feed port.

[0028] Preferably, the extrusion granulation process includes vacuum drying of the composite material melt, wherein the vacuum drying temperature is 60℃-70℃ and the time is 2 hours-4 hours.

[0029] Preferably, the temperature of the first temperature control zone is 160℃±2℃, the temperature of the second temperature control zone is 165℃±2℃, the temperature of the third temperature control zone is 170℃±2℃, the temperature of the fourth temperature control zone is 175℃±2℃, and the temperature of the machine head area is 180℃±2℃.

[0030] Applications of wollastonite fiber-reinforced polyvinyl chloride (PVC) composites include: their use in the preparation of high-impact-resistant building profiles and high-strength industrial pipe products.

[0031] This invention provides wollastonite fiber-reinforced polyvinyl chloride composite materials, their preparation methods, and applications. It offers the following beneficial effects:

[0032] The invention relates to a wollastonite fiber-reinforced polyvinyl chloride composite material, its preparation method, and its application. By subjecting wollastonite fibers to weak acid etching to form modified fibers, and combining this with high-speed mixing, segmented cooling, and melt blending processes, the material achieves high strength and high impact resistance.

[0033] A weak acid etching process using an oxalic acid-citric acid mixed solution creates a micro-nano dual-scale rough structure on the surface of the wollastonite fibers, improving the interfacial bonding between the fibers and polyvinyl chloride resin. Through efficient mixing, cooling, and melt blending, the composite material exhibits excellent mechanical properties and thermal stability, meeting the requirements for high-impact resistant building profiles and high-strength industrial piping products. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the surface modification process for wollastonite fibers used in this invention.

[0035] Figure 2 This is a process flow diagram for realizing the invention of high-speed mixing and segmented cooling;

[0036] Figure 3 This is a schematic diagram of the process configuration for implementing the invention using a twin-screw extruder;

[0037] Figure 4 It is a complete manufacturing process and product application flowchart for realizing the invention;

[0038] Figure 5 This is a schematic diagram illustrating the properties and reinforcement mechanism of wollastonite fibers used in the invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] like Figure 1-5 As shown, embodiments of the present invention provide a wollastonite fiber-reinforced polyvinyl chloride composite material, comprising the following components by mass percentage:

[0042] Polyvinyl chloride resin: 75%.

[0043] Wollastonite fiber: 11.4%.

[0044] Heat stabilizer: 2.6%.

[0045] Plasticizer: 4.9%.

[0046] Impact modifier: 4.1%.

[0047] Titanate coupling agent: 0.5%.

[0048] Lubricant: 0.5%.

[0049] Processing aids: 1%.

[0050] The wollastonite fiber has a needle-like structure, an aspect ratio of 8:1, a whiteness of >82%, a fiber diameter of 14μm, a heat stabilizer of calcium-zinc compounds, a plasticizer of diphenyl phosphate, and a lubricant of polyethylene wax.

[0051] A method for preparing wollastonite fiber-reinforced polyvinyl chloride composite materials includes:

[0052] S1. Modified wollastonite fibers are formed by weak acid etching treatment. The weak acid etching treatment uses a mixed solution of oxalic acid and citric acid. The surface of the modified wollastonite fibers has a micro-nano dual-scale rough structure. The oxalic acid-citric acid mixed solution includes oxalic acid and citric acid in a mass ratio of 1:5. The weak acid etching treatment temperature is 60℃ and the treatment time is 15 minutes. The modified wollastonite fibers are then dried at 80℃.

[0053] S2. Polyvinyl chloride resin, heat stabilizer, plasticizer, and lubricant are subjected to high-speed mixing to form a dry mix. The high-speed mixing process uses a high-speed mixer. The speed of the high-speed mixer is 800 rpm, the mixing time is 8 minutes, and the temperature is 110℃.

[0054] S3. The dry mixture is cooled to form a cooled mixture. The cooling process employs segmented cooling control and a cold mixer. The cold mixer uses circulating cooling water, and the segmented cooling control includes a rapid initial cooling stage, a medium cooling stage, and a stable cooling stage. The cooling process steps are as follows:

[0055] S31. In the rapid initial cooling stage, the dry mixture is cooled to 50°C to form the initial mixture. The cooling rate in the rapid initial cooling stage is 10°C / min.

[0056] S32. In the intermediate cooling stage, the temperature of the initial mixture is reduced to 35°C to form a room temperature mixture. The cooling rate in the intermediate cooling stage is 5°C / min.

[0057] S33. During the stable cooling stage, the temperature of the room temperature mixture is controlled below 30℃ to form a cooled mixture, and the cooling rate during the stable cooling stage is 3℃ / min.

[0058] S4. Modified wollastonite fibers and a cooled mixture are melt-blended to form a composite material melt. The melt-blending process is performed using a twin-screw extruder. The melt-blending process includes the addition of an impact modifier, a titanate coupling agent, and processing aids. The twin-screw extruder has an extrusion temperature of 160℃ and a screw speed of 150 rpm. The twin-screw extruder is equipped with a first temperature control zone, a second temperature control zone, a third temperature control zone, a fourth temperature control zone, and a die head area. The twin-screw extruder includes a main feed port and a side feed port. The main feed port is located at the beginning of the first temperature control zone, and the cooled mixture is added through the main feed port. The side feed port is located at the beginning of the third temperature control zone, and the modified wollastonite fibers are added through the side feed port. The temperature of the first temperature control zone is 158℃, the temperature of the second temperature control zone is 163℃, the temperature of the third temperature control zone is 168℃, the temperature of the fourth temperature control zone is 173℃, and the temperature of the die head area is 178℃.

[0059] S5. The composite material melt is extruded and granulated to form wollastonite fiber-reinforced polyvinyl chloride composite material particles. The extrusion granulation process includes vacuum drying of the composite material melt at a temperature of 60°C for 2 hours.

[0060] Applications of wollastonite fiber-reinforced polyvinyl chloride (PVC) composites include: their use in the preparation of high-impact-resistant building profiles and high-strength industrial pipe products.

[0061] This embodiment uses a low fiber content and minimal additives, resulting in poorer mechanical strength, impact toughness, and thermal stability of the composite material. However, this makes the material easier to process and suitable for cost-effective applications with lower performance requirements. The composite material in this embodiment exhibits good ductility and impact resistance, but its thermal stability and aging resistance are weak, and the low fiber content may lead to insufficient rigidity.

[0062] Example 2

[0063] This invention provides a wollastonite fiber-reinforced polyvinyl chloride composite material, comprising the following components by mass percentage:

[0064] Polyvinyl chloride resin: 66.7%.

[0065] Wollastonite fiber: 15%.

[0066] Heat stabilizer: 3.3%.

[0067] Plasticizer: 7%.

[0068] Impact modifier: 5.3%.

[0069] Titanate coupling agent: 0.7%.

[0070] Lubricant: 0.7%.

[0071] Processing aids: 1.5%.

[0072] The wollastonite fiber has a needle-like structure, an aspect ratio of 9:1, a whiteness of >82%, a fiber diameter of 15μm, a heat stabilizer of calcium-zinc compounds, a plasticizer of diphenyl phosphate, and a lubricant of polyethylene wax.

[0073] A method for preparing wollastonite fiber-reinforced polyvinyl chloride composite materials includes:

[0074] S1. Modified wollastonite fibers are formed by weak acid etching treatment. The weak acid etching treatment uses a mixed solution of oxalic acid and citric acid. The surface of the modified wollastonite fibers has a micro-nano dual-scale rough structure. The oxalic acid-citric acid mixed solution includes oxalic acid and citric acid in a mass ratio of 1:3. The weak acid etching treatment temperature is 70℃ and the treatment time is 22.5 minutes. The modified wollastonite fibers are then dried at 80℃.

[0075] S2. Polyvinyl chloride resin, heat stabilizer, plasticizer, and lubricant are subjected to high-speed mixing to form a dry mix. The high-speed mixing process uses a high-speed mixer. The speed of the high-speed mixer is 1000 rpm, the mixing time is 11.5 minutes, and the temperature is 110℃.

[0076] S3. The dry mixture is cooled to form a cooled mixture. The cooling process employs segmented cooling control and a cold mixer. The cold mixer uses circulating cooling water, and the segmented cooling control includes a rapid initial cooling stage, a medium cooling stage, and a stable cooling stage. The cooling process steps are as follows:

[0077] S31. In the rapid initial cooling stage, the dry mixture is cooled to 50°C to form the initial mixture. The cooling rate in the rapid initial cooling stage is 10°C / min.

[0078] S32. In the intermediate cooling stage, the temperature of the initial mixture is reduced to 35°C to form a room temperature mixture. The cooling rate in the intermediate cooling stage is 5°C / min.

[0079] S33. During the stable cooling stage, the temperature of the room temperature mixture is controlled below 30℃ to form a cooled mixture, and the cooling rate during the stable cooling stage is 3℃ / min.

[0080] S4. Modified wollastonite fibers and a cooled mixture are melt-blended to form a composite material melt. The melt-blending process is performed using a twin-screw extruder. The melt-blending process includes the addition of an impact modifier, a titanate coupling agent, and processing aids. The twin-screw extruder has an extrusion temperature of 165°C and a screw speed of 215 rpm. The twin-screw extruder is equipped with a first temperature control zone, a second temperature control zone, a third temperature control zone, a fourth temperature control zone, and a die head area. The twin-screw extruder includes a main feed port and a side feed port. The main feed port is located at the beginning of the first temperature control zone, and the cooled mixture is added through the main feed port. The side feed port is located at the beginning of the third temperature control zone, and the modified wollastonite fibers are added through the side feed port. The temperature of the first temperature control zone is 160°C, the temperature of the second temperature control zone is 165°C, the temperature of the third temperature control zone is 170°C, the temperature of the fourth temperature control zone is 175°C, and the temperature of the die head area is 180°C.

[0081] S5. The composite material melt is extruded and granulated to form wollastonite fiber-reinforced polyvinyl chloride composite material particles. The extrusion granulation process includes vacuum drying of the composite material melt at a temperature of 65°C for 3 hours.

[0082] Applications of wollastonite fiber-reinforced polyvinyl chloride (PVC) composites include: their use in the preparation of high-impact-resistant building profiles and high-strength industrial pipe products.

[0083] In this embodiment, the wollastonite fiber content is 15%, and the additive content is moderate, achieving a good balance in terms of mechanical strength, flexibility, and processability. The composite material formulated in this embodiment exhibits good performance and is suitable for applications requiring both strength and processability. By using high-speed mixing and appropriate temperature control, a uniform mixture is obtained, avoiding processing difficulties caused by excessively high fiber proportions. Regarding thermal stability and aging resistance, the material in this embodiment shows relatively stable performance, with improved durability under high-temperature environments.

[0084] Example 3

[0085] This invention provides a wollastonite fiber-reinforced polyvinyl chloride composite material, comprising the following components by mass percentage:

[0086] Polyvinyl chloride resin: 50.6%.

[0087] Wollastonite fiber: 22%.

[0088] Heat stabilizer: 4.5%.

[0089] Plasticizer: 11%.

[0090] Impact modifier: 7.5%.

[0091] Titanate coupling agent: 1.1%.

[0092] Lubricant: 1.1%.

[0093] Processing aids: 2.2%.

[0094] The wollastonite fiber has a needle-like structure, an aspect ratio of 10:1, a whiteness of >82%, a fiber diameter of 16μm, a heat stabilizer of calcium-zinc compounds, a plasticizer of diphenyl phosphate, and a lubricant of polyethylene wax.

[0095] A method for preparing wollastonite fiber-reinforced polyvinyl chloride composite materials includes:

[0096] S1. Modified wollastonite fibers are formed by weak acid etching treatment. The weak acid etching treatment uses a mixed solution of oxalic acid and citric acid. The surface of the modified wollastonite fibers has a micro-nano dual-scale rough structure. The oxalic acid-citric acid mixed solution includes oxalic acid and citric acid in a mass ratio of 1:1. The weak acid etching treatment temperature is 80℃ and the treatment time is 30 minutes. The modified wollastonite fibers are then dried at 80℃.

[0097] S2. Polyvinyl chloride resin, heat stabilizer, plasticizer, and lubricant are subjected to high-speed mixing to form a dry mix. The high-speed mixing process uses a high-speed mixer. The speed of the high-speed mixer is 1200 rpm, the mixing time is 15 minutes, and the temperature is 110℃.

[0098] S3. The dry mixture is cooled to form a cooled mixture. The cooling process employs segmented cooling control and a cold mixer. The cold mixer uses circulating cooling water, and the segmented cooling control includes a rapid initial cooling stage, a medium cooling stage, and a stable cooling stage. The cooling process steps are as follows:

[0099] S31. In the rapid initial cooling stage, the dry mixture is cooled to 50°C to form the initial mixture. The cooling rate in the rapid initial cooling stage is 10°C / min.

[0100] S32. In the intermediate cooling stage, the temperature of the initial mixture is reduced to 35°C to form a room temperature mixture. The cooling rate in the intermediate cooling stage is 5°C / min.

[0101] S33. During the stable cooling stage, the temperature of the room temperature mixture is controlled below 30℃ to form a cooled mixture, and the cooling rate during the stable cooling stage is 3℃ / min.

[0102] S4. Modified wollastonite fibers and a cooled mixture are melt-blended to form a composite material melt. The melt-blending process is performed using a twin-screw extruder. The melt-blending process includes the addition of an impact modifier, a titanate coupling agent, and processing aids. The twin-screw extruder has an extrusion temperature of 170°C and a screw speed of 180 rpm. The twin-screw extruder is equipped with a first temperature control zone, a second temperature control zone, a third temperature control zone, a fourth temperature control zone, and a die head area. The twin-screw extruder includes a main feed port and a side feed port. The main feed port is located at the beginning of the first temperature control zone, and the cooled mixture is added through the main feed port. The side feed port is located at the beginning of the third temperature control zone, and the modified wollastonite fibers are added through the side feed port. The temperatures in the first temperature control zone are 162°C, the second temperature control zone is 167°C, the third temperature control zone is 172°C, the fourth temperature control zone is 177°C, and the die head area temperature is 182°C.

[0103] S5. The composite material melt is extruded and granulated to form wollastonite fiber-reinforced polyvinyl chloride composite material particles. The extrusion granulation process includes vacuum drying of the composite material melt at a temperature of 70°C for 4 hours.

[0104] Applications of wollastonite fiber-reinforced polyvinyl chloride (PVC) composites include: their use in the preparation of high-impact-resistant building profiles and high-strength industrial pipe products.

[0105] This embodiment employs the highest wollastonite fiber content and the most additives, resulting in a composite material with higher mechanical strength, durability, and thermal stability. The higher fiber content may present challenges during processing; higher extrusion temperatures and screw speeds may affect material uniformity. Regarding surface modification, longer weak acid etching times and higher temperatures help improve the bonding strength between the fibers and PVC resin, enhancing the mechanical properties of the composite. The material in this embodiment may face higher production costs and more complex processing techniques, thus it is suitable for applications with extremely high performance requirements. In terms of thermal stability and aging resistance, the higher additive ratio contributes to improved long-term stability of the material.

[0106] Example 4

[0107] This embodiment is based on wollastonite fiber-reinforced polyvinyl chloride (PVC) composites, their preparation methods, and applications. It compares the mechanical properties, thermal stability, and processability of PVC composites with three different formulations, and evaluates the impact of different formulations on the composite material's performance based on experimental data. Experimental data will be presented gradually in each test, and the optimal application choice will be determined by comparing the performance of different formulations. Specific implementation methods are as follows:

[0108] 1. Experimental formula

[0109] To conduct a comparative experiment, three different formulations were selected, as shown in the table below:

[0110] Table 1: Experimental formulation data table.

[0111] formula Polyvinyl chloride resin Wollastonite fiber Heat stabilizer plasticizer Impact modifier titanate coupling agent lubricant Processing aids Experiment A 75% 11.4% 2.6% 4.9% 4.1% 0.5% 0.5% 1% Experiment B 66.7% 15% 3.3% 7% 5.3% 0.7% 0.7% 1.5% Experiment C 50.6% 22% 4.5% 11% 7.5% 1.1% 1.1% 2.2%

[0112] 2. Material Preparation

[0113] Prepare the raw materials according to the proportions of each formula, and pre-treat them according to the following steps:

[0114] Modification of wollastonite fibers: A weak acid etching treatment was performed on wollastonite fibers using a mixed solution of oxalic acid and citric acid at mass ratios of 1:5, 1:3, and 1:1. The etching temperatures were 60℃, 70℃, and 80℃, and the treatment times were 15 minutes, 22.5 minutes, and 30 minutes, respectively. This resulted in a micro-nano dual-scale rough structure on the surface of the wollastonite fibers, improving the bonding strength between the oxalic acid-citric acid mixed solution and polyvinyl chloride resin.

[0115] Mixing polyvinyl chloride resin with additives: Polyvinyl chloride resin, heat stabilizer, plasticizer, lubricant, etc. are mixed at high speeds of 800 rpm, 1000 rpm, and 1200 rpm, respectively, for 8 minutes, 11.5 minutes, and 15 minutes, respectively, while maintaining the temperature at 110℃.

[0116] 3. Blending and Extrusion

[0117] Cooling treatment: The mixed material is cooled in stages at cooling rates of 10℃ / min, 5℃ / min and 3℃ / min, respectively, and the temperature is finally controlled below 30℃.

[0118] Melt blending: Modified wollastonite fibers and the cooled mixture were fed into a twin-screw extruder for melt blending. The screw speeds were 150 rpm, 215 rpm, and 180 rpm, and the extrusion temperatures were 160℃, 165℃, and 170℃, respectively. Finally, the composite melt was vacuum dried at temperatures of 60℃, 65℃, and 70℃ for 2 hours, 3 hours, and 4 hours, respectively.

[0119] 4. Experimental Testing

[0120] Mechanical property testing:

[0121] Each composite material formulation was tested for tensile strength, flexural strength, and impact strength. The specific testing procedures are as follows:

[0122] Tensile strength: The composite material samples were subjected to tensile testing using a standard tensile testing machine, and the stress at the failure point was recorded.

[0123] Bending strength: The bending modulus and maximum bending stress of the material are measured by a three-point bending test.

[0124] Impact strength: The impact toughness of a material is measured using a notched impact test.

[0125] Thermal stability test:

[0126] The thermal stability of the composite material was assessed using thermogravimetric analysis and differential scanning calorimetry.

[0127] Thermogravimetric analysis: Record the percentage of weight loss for each sample at 200°C to assess thermal stability.

[0128] Differential scanning calorimetry: measures the glass transition temperature of a material to evaluate its thermal deformation properties.

[0129] Processability test:

[0130] The melt flowability and molding stability of each composite material were tested.

[0131] Melt flowability: The melt flowability of a material is measured using a melt indexer to evaluate its processing performance.

[0132] Molding stability: The molding stability of composite materials is determined by monitoring temperature and flowability during the production process.

[0133] 5. Analysis of Experimental Results

[0134] Mechanical properties:

[0135] The mechanical property test results reflect the performance of each formulation in different tests:

[0136] Experiment A exhibited a low tensile strength of 36 MPa and an impact strength of 6.5 kJ / m², indicating that the formulation in Experiment A has poor mechanical properties and is suitable for low-strength applications. The flexural strength was 62 MPa, which is relatively average, indicating that the material has low rigidity.

[0137] Experiment B showed improvements over Experiment A in tensile strength (52 MPa), flexural strength (83 MPa), and impact strength (9.2 kJ / m²), demonstrating better overall performance. The formulation in Experiment B is suitable for applications with moderate mechanical property requirements.

[0138] Experiment C exhibited the best performance in all mechanical properties, with tensile strength of 68 MPa, flexural strength of 95 MPa, and impact strength of 12.3 kJ / m² all significantly higher than those of Experiments A and B, making it suitable for applications requiring high strength and impact resistance.

[0139] Thermal stability:

[0140] Thermal stability test data reveals the performance of each formulation in high-temperature environments:

[0141] Experiment A exhibits a thermal weight loss of 6% at 200℃ and a glass transition temperature of 85℃, demonstrating low thermal stability and suitability for applications in low-temperature environments.

[0142] Experiment B exhibits a thermal weight loss of 5.5% and a glass transition temperature of 92℃, demonstrating moderate thermal stability and suitability for applications in medium-temperature environments.

[0143] Experiment C exhibits the lowest thermal weight loss at 4.8% and the highest glass transition temperature at 98℃, making it suitable for applications in high-temperature environments and demonstrating strong thermal stability.

[0144] Processability:

[0145] Processability test results reflect the performance of each composite material during the molding process:

[0146] Experiment A exhibited a melt flow rate of 6.2 g / 10 min, demonstrating good processing performance and suitability for large-scale production.

[0147] Experiment B exhibited a melt flowability of 5.3 g / 10 min and good molding stability, making it suitable for applications requiring high processing precision.

[0148] Experiment C exhibited a melt flow rate of 4.8 g / 10 min, indicating poor processability, which may lead to higher production costs and processing difficulties.

[0149] Based on the above steps and the experimental data, the following conclusions can be drawn:

[0150] Experiment A is suitable for applications with low performance requirements and has good machinability, but performs poorly in terms of mechanical properties and thermal stability. Experiment B provides a good balance between mechanical properties, thermal stability, and machinability, and is suitable for applications with moderate overall performance requirements. Experiment C has the best mechanical properties and thermal stability, and is suitable for applications in high-strength and high-temperature environments, but is more difficult to process and is suitable for applications with high performance requirements.

[0151] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A wollastonite fiber-reinforced polyvinyl chloride composite material, characterized in that, It consists of the following components by mass percentage: Polyvinyl chloride resin: 50%-75%; Wollastonite fiber: 8%-22%; Heat stabilizer: 2%-4.5%; Plasticizer: 3%-11%; Impact modifier: 3%-7.5%; Titanate coupling agent: 0.3%-1.1%; Lubricant: 0.3%-1.1%; Processing aids: 0.7%-2.2%.

2. The wollastonite fiber-reinforced polyvinyl chloride composite material according to claim 1, characterized in that: The wollastonite fiber has a needle-like structure, an aspect ratio of 8:1-10:1, a whiteness >82%, and a fiber diameter of 14μm-16μm. The heat stabilizer is a calcium-zinc compound, the plasticizer is diphenyl phosphate, and the lubricant is polyethylene wax.

3. A method for preparing wollastonite fiber-reinforced polyvinyl chloride composite material, characterized in that, include: S1. Wollastonite fibers are subjected to weak acid etching treatment to form modified wollastonite fibers. The weak acid etching treatment uses a mixed solution of oxalic acid and citric acid. The surface of the modified wollastonite fibers has a micro-nano dual-scale rough structure. S2. Polyvinyl chloride resin, heat stabilizer, plasticizer and lubricant are subjected to high-speed mixing to form a dry mixture, wherein the high-speed mixing is performed using a high-speed mixer; S3. The dry mixture is cooled to form a cooled mixture. The cooling process is controlled by segmented cooling and is performed using a cold mixer. S4. The modified wollastonite fiber and the cooled mixture are melt-blended to form a composite material melt, wherein the melt-blending process is performed using a twin-screw extruder; S5. The composite material melt is subjected to extrusion granulation to form wollastonite fiber-reinforced polyvinyl chloride composite material particles.

4. The method for preparing wollastonite fiber reinforced polyvinyl chloride composite material according to claim 3, characterized in that: The oxalic acid-citric acid mixed solution includes oxalic acid and citric acid, with a mass ratio of oxalic acid to citric acid of 1:1 to 1:

5. The weak acid etching treatment is performed at a temperature of 60°C to 80°C for 15 to 30 minutes, and the modified wollastonite fiber is dried at 80°C.

5. The method for preparing wollastonite fiber-reinforced polyvinyl chloride composite material according to claim 3, characterized in that: The high-speed mixer operates at a speed of 800 rpm to 1200 rpm, and the high-speed mixing process takes 8 to 15 minutes at a temperature of 110°C.

6. The method for preparing wollastonite fiber reinforced polyvinyl chloride composite material according to claim 3, characterized in that: The refrigeration mixer uses circulating cooling water, and the segmented cooling control includes a rapid initial cooling stage, a medium cooling stage, and a stable cooling stage. The cooling process involves the following steps: S31. In the rapid initial cooling stage, the dry mixture is cooled to 50°C to form an initial mixture, and the cooling rate of the rapid initial cooling stage is 10°C / min; S32. In the intermediate cooling stage, the temperature of the initial mixture is reduced to 35°C to form a room temperature mixture, and the cooling rate of the intermediate cooling stage is 5°C / min; S33. In the stable cooling stage, the temperature of the room temperature mixture is controlled below 30°C to form the cooled mixture, and the cooling rate of the stable cooling stage is 3°C / min.

7. The method for preparing wollastonite fiber reinforced polyvinyl chloride composite material according to claim 3, characterized in that: The melt blending process includes the addition of an impact modifier, a titanate coupling agent, and a processing aid. The twin-screw extruder has an extrusion temperature of 160℃-170℃ and a screw speed of 150rpm-180rpm. The twin-screw extruder is equipped with a first temperature control zone, a second temperature control zone, a third temperature control zone, a fourth temperature control zone, and a die head area. The twin-screw extruder includes a main feed port and a side feed port. The main feed port is located at the beginning of the first temperature control zone, and the cooled mixture is added through the main feed port. The side feed port is located at the beginning of the third temperature control zone, and the modified wollastonite fiber is added through the side feed port.

8. The method for preparing wollastonite fiber reinforced polyvinyl chloride composite material according to claim 3, characterized in that: The extrusion granulation process includes vacuum drying of the composite material melt, wherein the vacuum drying temperature is 60℃-70℃ and the time is 2 hours-4 hours.

9. The method for preparing wollastonite fiber reinforced polyvinyl chloride composite material according to claim 7, characterized in that: The temperature of the first temperature control zone is 160℃±2℃, the temperature of the second temperature control zone is 165℃±2℃, the temperature of the third temperature control zone is 170℃±2℃, the temperature of the fourth temperature control zone is 175℃±2℃, and the temperature of the machine head area is 180℃±2℃.

10. The application of wollastonite fiber-reinforced polyvinyl chloride composite materials, characterized in that, include: Wollastonite fiber-reinforced polyvinyl chloride composites are used in the preparation of high-impact-resistant building profiles and high-strength industrial pipe products.

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