Polycarbonate composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high polymer materials. The invention provides a polycarbonate composite material. The polycarbonate composite material is mainly prepared from the following components in parts by weight: 70-80 parts of polycarbonate resin, 8-12 parts of carbon fibers, 6-14 parts of coupled potassium titanate whiskers, 2-8 parts of a liquid crystal polymer, 1-2 parts of a toughening agent, 0.5-1 part of an antioxidant and 0.5-1 part of a lubricant. The invention also provides a preparation method of the polycarbonate composite material. The invention further provides application of the polycarbonate composite material in the fields of automotive interiors, unmanned aerial vehicle shells, robot exoskeletons, low-temperature storage devices, electronics and electrics, household appliances, aerospace and the like. The polycarbonate composite material prepared by the invention not only shows high strength and good toughness at normal temperature, but also can maintain most of mechanical properties under the extreme condition of-60 DEG C, does not generate obvious embrittlement, and can be widely applied to the field of structural parts with higher low-temperature reliability requirements.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a polycarbonate material, its preparation method, and its applications. Background Technology

[0002] Polycarbonate (PC) resin is an important lightweight and functional engineering plastic in fields such as automotive interiors, drone shells, and robot exoskeletons due to its excellent impact toughness, good dimensional stability, and heat resistance. However, with technological iterations, such as the expansion of high-end special robots into more complex and extreme environments, unprecedented stringent challenges have been placed on the comprehensive performance of structural materials, especially the mechanical properties and reliability in low-temperature environments (such as -30°C to -60°C).

[0003] The glass transition temperature (Tg) of pure PC is approximately 145℃. At temperatures far below Tg, the mobility of its molecular chains decreases dramatically, causing the material to transition from ductile fracture at room temperature to brittle fracture. This results in a significant deterioration in notched impact strength, failing to meet the impact resistance requirements of high-reliability components. Furthermore, the components of polycarbonate composites prepared using conventional methods exhibit poor compatibility at low temperatures. The interface between the PC matrix and rigid fillers / toughening agents experiences greater internal stress due to differences in thermal shrinkage coefficients, easily leading to interfacial debonding and becoming a weak point in material failure.

[0004] Therefore, developing a polycarbonate composite material that can maintain good mechanical properties under extreme low-temperature environments has become a key technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a polycarbonate material, its preparation method, and its applications. The polycarbonate composite material prepared by this invention not only exhibits high strength, high modulus, and good toughness at room temperature, but also retains most of its mechanical properties under extreme conditions of -60℃ without significant embrittlement. It can be widely used in automotive interior and exterior parts, drone shells, robot exoskeletons, cryogenic storage devices, and other structural components with high requirements for low-temperature reliability.

[0006] The technical solution of this invention is implemented as follows: A polycarbonate composite material is mainly prepared from the following components in parts by weight: 70-80 parts polycarbonate resin, 8-12 parts carbon fiber, 6-14 parts coupled potassium titanate whiskers, 2-8 parts liquid crystal polymer, 1-2 parts toughening agent, 0.5-1 part antioxidant, and 0.5-1 part lubricant. Preferably, a polycarbonate composite material is mainly prepared from the following components in parts by weight: 73-75 parts polycarbonate resin, 10 parts carbon fiber, 6-12 parts coupled potassium titanate whiskers, 2-6 parts liquid crystal polymer, 2 parts toughening agent, 0.5 parts antioxidant, and 0.5 parts lubricant.

[0007] The polycarbonate composite material described above has a melt flow rate (MFR) of 5–15 g / 10 min at 300°C and 1.2 kg. Since the present invention contains carbon fiber and potassium titanate whisker rigid fillers, which have poor flowability, selecting polycarbonate resin under these conditions can partially offset the increase in melt viscosity caused by the addition of a large amount of rigid filler, ensuring good processability.

[0008] In the polycarbonate composite material described above, the carbon fiber is chopped carbon fiber with a length of 3mm to 6mm. Carbon fiber, as a traditional reinforcing phase with high modulus and high strength, can significantly improve the deformation resistance of the polycarbonate resin matrix. After dispersion in polycarbonate resin, chopped carbon fiber can effectively construct a rigid skeleton. Chopped fibers selected under these conditions are preferable because if the fiber length is too short (less than 3mm), the reinforcing effect is poor; if the fiber length is too long (more than 6mm), it will entangle during processing. Therefore, a carbon fiber length of 3mm to 6mm is chosen.

[0009] As described above, the polycarbonate composite material is obtained by surface treatment of the coupled potassium titanate whiskers using a coupling agent. The coupling agent is any one of silane coupling agents, titanate coupling agents, aluminate coupling agents, and phosphate coupling agents. Preferably, the coupling agent is a silane coupling agent. More preferably, the silane coupling agent is purchased from Momentive Advanced Materials (USA), model: Silquest A-1100, specifically γ-aminopropyltriethoxysilane. Under these conditions, the siloxane portion of the silane coupling agent hydrolyzes to silanols. These silanols can undergo a condensation reaction with the hydroxyl groups (-OH) on the surface of the potassium titanate whiskers to form Si-O-Ti covalent bonds, achieving interfacial chemical bonding.

[0010] In the polycarbonate composite material described above, preferably, the weight ratio of the coupled potassium titanate whiskers to the liquid crystal polymer is (6-12):(2-6). More preferably, the weight ratio of the coupled potassium titanate whiskers to the liquid crystal polymer is 6:6. The polycarbonate composite material prepared under these conditions exhibits optimal tensile strength, flexural strength, and impact toughness at room temperature and extreme low temperatures (-60°C).

[0011] In the polycarbonate composite material described above, the toughening agent is a core-shell structured acrylate toughening agent. Under these conditions, the core-shell structured acrylate toughening agent solves the brittleness problem of the polycarbonate matrix at low temperatures by converting the mechanical energy of the impact into controllable plastic deformation work. On the other hand, although the Si-O-Ti or Si-OC covalent bonds of the silane coupling agent have high strength, they connect two completely different materials: a rigid inorganic material and a flexible organic polymer. When subjected to impact at low temperatures, stress concentration can lead to interfacial debonding. The core-shell structured acrylate toughening agent absorbs the stress on the chemical bonds, thus solving the interfacial debonding problem of the composite material.

[0012] In the polycarbonate composite material described above, the antioxidant is a mixture of any two of antioxidants 1010, 168, 3114, and 626. Preferably, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a 1:1 mass ratio.

[0013] In the polycarbonate composite material described above, the lubricant is selected from at least one of fatty acid ester lubricants, fatty acid amide lubricants, polyethylene wax, or polytetrafluoroethylene wax. Preferably, the lubricant is selected from fatty acid ester lubricants; more preferably, the lubricant is selected from Clariant Licowax E. Since the formulation of this invention contains a large amount of solid filler, which increases melt viscosity, using this lubricant overcomes the disadvantages of viscosity, ensuring smooth extrusion and injection molding of the material.

[0014] In low-temperature environments, polycarbonate systems are prone to chain segment freezing, decreased toughness, and brittle fracture. Therefore, the key to improving low-temperature mechanical retention lies in constructing a multi-scale reinforcing structure that can disperse stress, inhibit crack propagation, and maintain interfacial stability. In the composite system of this invention, coupled potassium titanate, liquid crystal polymer, and carbon fiber form a synergistic low-temperature resistance mechanism that compensates for and supports each other within the polycarbonate matrix. First, the coupled potassium titanate crystals, through surface activation, improve the interfacial bonding force between them and the polycarbonate and carbon fibers, making the interface less prone to debonding or microcracks at low temperatures. In addition, the core-shell structured acrylate toughening agent acts as a flexible buffer unit, further preventing low-temperature brittle debonding of the interface. The high-modulus structure of the coupled potassium titanate crystals can serve as a stable "microscale skeleton," distributing stress concentration during sudden temperature drops and inhibiting the initiation of brittle fracture. Secondly, the liquid crystal polymer forms an oriented fibrous microstructure during melt processing, exhibiting a low glass transition temperature and maintaining a certain degree of flexibility even at low temperatures. Its fibrous network, distributed throughout the polycarbonate matrix, effectively prevents rapid crack propagation and provides a "toughness channel," compensating for the toughness loss of polycarbonate and inorganic fillers at low temperatures. Carbon fibers, as a macroscopic reinforcing phase, constitute the main load-bearing pathway of the material. During low-temperature shrinkage, the coefficient of thermal expansion of carbon fibers is significantly lower than that of polycarbonate. When coexisting with coupled potassium titanate whiskers and the liquid crystal polymer, carbon fibers no longer bear interfacial stress alone; instead, a smoother stress transition is achieved through these two mesoscale reinforcing phases, thus avoiding debonding and fracture at low temperatures due to thermal strain mismatch. The polycarbonate matrix then acts as a continuous phase, stably binding the aforementioned reinforcing structure together. Coupling potassium titanate whiskers improve interfacial adhesion, flexible polycarbonate segments supplement its toughness, carbon fiber provides overall structural strength, and toughening agents improve notched impact toughness. These components together constitute a multi-level reinforcement structure from nanoscale, microscale to macroscale, making the stress distribution more uniform at low temperatures, the crack propagation path longer, and the energy dissipation more efficient, thereby achieving a significantly higher low-temperature mechanical property retention rate than traditional polycarbonate composites.

[0015] Based on the same inventive concept, the present invention provides a method for preparing a polycarbonate composite material, the method comprising the following steps: S1. Raw material drying and weighing: Dry the polycarbonate resin and carbon fiber separately under vacuum, and weigh them according to the set ratio after drying for later use; weigh the coupling potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant and lubricant according to the set ratio for later use. S2. Premixing: Place the polycarbonate resin, coupled potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant weighed in step S1 into a high-speed mixer and mix at room temperature for 3-5 minutes to obtain a premix. S3. Twin-screw extrusion granulation: The premixed material described in step S2 is added from the main feed port of a parallel co-rotating twin-screw extruder; the carbon fiber weighed in step S1 is added through the side feed port in the middle section of the twin screw; the extruder temperature is set; the screw speed is set to 150-200 rpm to maintain melt shearing and mixing; the melt is extruded through the die head, water-cooled, and pelletized to obtain composite material particles, which are polycarbonate composite materials.

[0016] The preparation method of the polycarbonate composite material as described above, in step S1, the preparation method of the coupling potassium titanate whiskers includes the following steps: preparing a solution as a treatment solution by mixing deionized water and anhydrous ethanol at a volume ratio of 15:85, adjusting the pH to 4-5, adding the coupling agent and potassium titanate whiskers into the treatment solution, wherein the liquid-solid ratio of the treatment solution to the potassium titanate whiskers is (10-20) mL:1g, and the mass of the coupling agent is 2%-3% of the mass of the potassium titanate whiskers, and mechanically stirring at a constant temperature of 60-80℃ for 2-4 hours. After the reaction is completed, the mixture is filtered, the filter cake is washed 2-3 times with anhydrous ethanol, and then dried at a temperature of 100-120℃ for 2-4 hours to obtain the coupling potassium titanate whiskers.

[0017] In the preparation method of polycarbonate composite material as described above, in step S3, the extruder temperature is set as follows: the feeding port area is 220-230°C, the plasticizing area is 240-250°C, the metering area is 250-255°C, and the die head temperature is 250-260°C.

[0018] Based on the same inventive concept, this invention provides the application of polycarbonate composite materials as described above or polycarbonate composite materials prepared by the preparation method as described above in automotive interiors, drone shells, robot exoskeletons, cryogenic storage devices, electronics and electrical appliances, home appliances, aerospace, sports equipment, and medical devices.

[0019] Compared with existing technologies, the beneficial effects and advantages of this invention are: 1. The polycarbonate composite material provided by this invention not only exhibits high strength, high modulus and good toughness at room temperature, but also retains most of its mechanical properties under extreme conditions of -60°C without significant embrittlement. It can be widely used in automotive interior and exterior parts, drone shells, robot exoskeletons, cryogenic storage devices and other structural components with high requirements for low-temperature reliability.

[0020] 2. The polycarbonate composite material provided by this invention, according to TGA testing, shows that in the preferred embodiment, the peak value of the maximum thermal decomposition rate occurs at 489.7℃, indicating that the thermal motion and breakage of the polymer molecular chains are effectively suppressed, thereby significantly improving the overall heat resistance of the composite material; FTIR testing shows that during the blending process of the multi-component complex system, each component remains chemically stable, and no side reactions occur that lead to polymer degradation, which provides a chemical basis for the excellent mechanical properties.

[0021] 3. This invention provides a method for preparing a polycarbonate composite material. A dense, multi-scale "skeleton-interface-matrix" structure with a continuous load transfer path is established through twin-screw melt blending. Surface treatment of potassium titanate whiskers ensures that the reinforcing phase maintains effective stress conduction even in low-temperature shrinkage environments, preventing microcracks caused by thermal mismatch. Furthermore, this invention optimizes molding conditions to achieve a balanced release of residual stress within the polycarbonate composite material, thereby endowing the material with excellent low-temperature impact resistance. Attached Figure Description

[0022] Figure 1 The scanning electron microscope image, elemental analysis description diagram, and elemental energy spectrum diagram of the polycarbonate composite material provided in Example 3 of the present invention are shown below. Figure 2 Scanning electron microscope image of the polycarbonate composite material provided for Comparative Example 1; Figure 3 Scanning electron microscope image of the polycarbonate composite material provided for Comparative Example 2; Figure 4 Scanning electron microscope image and elemental analysis description diagram of the polycarbonate composite material provided for Comparative Example 3; Figure 5 TGA diagram of the polycarbonate composite material provided in Example 3; Figure 6 TGA diagram of the polycarbonate composite material provided for Comparative Example 3; Figure 7 The image shows the FTIR plot of the polycarbonate composite material provided in Example 3. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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.

[0024] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0025] The raw materials used in the following examples and comparative examples are as follows: Polycarbonate resin, purchased from SABIC, model: LEXAN™ 141R; Carbon fiber, purchased from Jiangsu Deqing New Materials Co., Ltd., model: DQL-PC; Potassium titanate whiskers, purchased from Shanghai Whisker Composite Materials Manufacturing Co., Ltd., model: JXB-1B; Silane coupling agent, purchased from Momentive Advanced Materials Group, USA, model: Silquest A-1100; Liquid crystal polymer, purchased from Celanese, model: Vectra ® B230; Toughening agent, purchased from Muye New Material Technology (Shanghai) Co., Ltd., model: Duragerength ® 480.

[0026] Antioxidant 1010 and Antioxidant 168 were purchased from BASF. The antioxidants used in the examples and comparative examples of this invention are a mixture of antioxidant 1010 and antioxidant 168 in a 1:1 mass ratio.

[0027] Lubricant, purchased from Shenzhen Huicheng Plastic Additives & Chemicals Co., Ltd., model: Clariant Licowax E.

[0028] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods.

[0029] Unless otherwise specified, all materials and reagents used in the following examples and comparative examples are commercially available.

[0030] Example 1 A polycarbonate composite material is mainly prepared from the following components in parts by weight: 73 parts polycarbonate resin, 10 parts carbon fiber, 12 parts coupled potassium titanate whiskers, 2 parts liquid crystal polymer, 2 parts toughening agent, 0.5 parts antioxidant, and 0.5 parts lubricant.

[0031] The preparation method of this polycarbonate composite material includes the following steps: S1. Vacuum dry the polycarbonate resin at 80℃ for 4 hours and the carbon fiber at 100℃ for 2 hours. After drying, weigh them according to the set ratio and set aside. Weigh the coupling potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant according to the set ratio and set aside. In step S1, the preparation method of coupled potassium titanate whiskers includes the following steps: a solution is prepared by mixing deionized water and anhydrous ethanol at a volume ratio of 15:85 as a treatment solution, the pH is adjusted to 4-5 with acetic acid, and the coupling agent and potassium titanate whiskers are placed in the treatment solution. The liquid-solid ratio of the treatment solution to the potassium titanate whiskers is 20 mL: 1 g, and the mass of the coupling agent is 3% of the mass of the potassium titanate whiskers. The mixture is mechanically stirred at 60°C for 2 h. After the reaction is completed, the mixture is filtered, the filter cake is washed 2-3 times with anhydrous ethanol, and then dried at 120°C for 2 h to obtain coupled potassium titanate whiskers.

[0032] S2. Premix: Place the polycarbonate resin, coupled potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant weighed in step S1 into a high-speed mixer and mix at room temperature for 5 minutes to obtain a premix. S3. Twin-screw extrusion granulation: The premixed material described in step S2 is added from the main feed port of a parallel co-rotating twin-screw extruder; the carbon fiber weighed in step S1 is added through the side feed port in the middle section of the twin screw; the extruder temperature is set as follows: 230°C in the feeding port area, 240°C in the plasticizing zone, 250°C in the metering zone, and 260°C in the die head; the screw speed is set to 150 rpm to maintain melt shearing and mixing; the melt is extruded through the die head, water-cooled, and pelletized to obtain composite material particles, which are polycarbonate composite materials.

[0033] Example 2 A polycarbonate composite material is mainly prepared from the following components in parts by weight: 75 parts polycarbonate resin, 10 parts carbon fiber, 9 parts coupled potassium titanate whiskers, 3 parts liquid crystal polymer, 2 parts toughening agent, 0.5 parts antioxidant, and 0.5 parts lubricant.

[0034] The preparation method of this polycarbonate composite material includes the following steps: S1. Vacuum dry the polycarbonate resin at 80℃ for 4 hours and the carbon fiber at 100℃ for 2 hours. After drying, weigh them according to the set ratio and set aside. Weigh the coupling potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant according to the set ratio and set aside. In step S1, the preparation method of coupled potassium titanate whiskers includes the following steps: a solution is prepared by mixing deionized water and anhydrous ethanol at a volume ratio of 15:85 as a treatment solution, the pH is adjusted to 4-5 with acetic acid, and the coupling agent and potassium titanate whiskers are placed in the treatment solution. The liquid-solid ratio of the treatment solution to the potassium titanate whiskers is 20 mL: 1 g, and the mass of the coupling agent is 3% of the mass of the potassium titanate whiskers. The mixture is mechanically stirred at 60°C for 2 h. After the reaction is completed, the mixture is filtered, the filter cake is washed 2-3 times with anhydrous ethanol, and then dried at 120°C for 2 h to obtain coupled potassium titanate whiskers.

[0035] S2. Premix: Place the polycarbonate resin, coupled potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant weighed in step S1 into a high-speed mixer and mix at room temperature for 3 minutes to obtain a premix. S3. Twin-screw extrusion granulation: The premixed material described in step S2 is added from the main feed port of a parallel co-rotating twin-screw extruder; the carbon fiber weighed in step S1 is added through the side feed port in the middle section of the twin screw; the extruder temperature is set as follows: 220°C in the feeding port area, 250°C in the plasticizing zone, 255°C in the metering zone, and 250°C in the die head; the screw speed is set to 200 rpm to maintain melt shearing and mixing; the melt is extruded through the die head, water-cooled, and pelletized to obtain composite material particles, which are polycarbonate composite materials.

[0036] Example 3 A polycarbonate composite material is mainly prepared from the following components in parts by weight: 75 parts polycarbonate resin, 10 parts carbon fiber, 6 parts coupled potassium titanate whiskers, 6 parts liquid crystal polymer, 2 parts toughening agent, 0.5 parts antioxidant, and 0.5 parts lubricant.

[0037] The preparation method of this polycarbonate composite material includes the following steps: S1. Vacuum dry the polycarbonate resin at 80℃ for 4 hours and the carbon fiber at 100℃ for 2 hours. After drying, weigh them according to the set ratio and set aside. Weigh the coupling potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant according to the set ratio and set aside. In step S1, the preparation method of coupled potassium titanate whiskers includes the following steps: a solution is prepared by mixing deionized water and anhydrous ethanol at a volume ratio of 15:85 as a treatment solution, the pH is adjusted to 4-5 with acetic acid, and the coupling agent and potassium titanate whiskers are placed in the treatment solution. The liquid-solid ratio of the treatment solution to the potassium titanate whiskers is 20 mL: 1 g, and the mass of the coupling agent is 3% of the mass of the potassium titanate whiskers. The mixture is mechanically stirred at 60°C for 2 h. After the reaction is completed, the mixture is filtered, the filter cake is washed 2-3 times with anhydrous ethanol, and then dried at 120°C for 2 h to obtain coupled potassium titanate whiskers.

[0038] S2. Premix: Place the polycarbonate resin, coupled potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant weighed in step S1 into a high-speed mixer and mix at room temperature for 5 minutes to obtain a premix. S3. Twin-screw extrusion granulation: The premixed material described in step S2 is added from the main feed port of a parallel co-rotating twin-screw extruder; the carbon fiber weighed in step S1 is added through the side feed port in the middle section of the twin screw; the extruder temperature is set as follows: 225°C in the feeding port area, 245°C in the plasticizing zone, 255°C in the metering zone, and 255°C in the die head; the screw speed is set to 150 rpm to maintain melt shearing and mixing; the melt is extruded through the die head, water-cooled, and pelletized to obtain composite material particles, which are polycarbonate composite materials.

[0039] Comparative Example 1 The difference from Example 3 is that this comparative example does not contain liquid crystal polymer. The polycarbonate composite material provided in this comparative example is mainly prepared from the following components in parts by weight: 81 parts polycarbonate resin, 10 parts carbon fiber, 6 parts coupled potassium titanate whiskers, 2 parts toughening agent, 0.5 parts antioxidant, and 0.5 parts lubricant.

[0040] The preparation method of this polycarbonate composite material includes the following steps: S1. Raw material weighing: Vacuum dry polycarbonate resin at 80℃ for 4 hours and carbon fiber at 100℃ for 2 hours. Weigh them according to the set ratio after drying and set aside. Weigh the coupling potassium titanate whiskers, toughening agent, antioxidant and lubricant according to the set ratio and set aside. In step S1, the preparation method of coupled potassium titanate whiskers includes the following steps: a solution is prepared by mixing deionized water and anhydrous ethanol at a volume ratio of 15:85 as a treatment solution, the pH is adjusted to 4-5 with acetic acid, and the coupling agent and potassium titanate whiskers are placed in the treatment solution. The liquid-solid ratio of the treatment solution to the potassium titanate whiskers is 20 mL: 1 g, and the mass of the coupling agent is 3% of the mass of the potassium titanate whiskers. The mixture is mechanically stirred at 60°C for 2 h. After the reaction is completed, the mixture is filtered, the filter cake is washed 2-3 times with anhydrous ethanol, and then dried at 120°C for 2 h to obtain coupled potassium titanate whiskers.

[0041] S2. Premix: Place the polycarbonate resin, coupled potassium titanate whiskers, toughening agent, antioxidant, and lubricant weighed in step S1 into a high-speed mixer and mix for 5 minutes at room temperature to obtain a premix. S3. Twin-screw extrusion granulation: The premixed material described in step S2 is added from the main feed port of a parallel co-rotating twin-screw extruder; the carbon fiber weighed in step S1 is added through the side feed port in the middle section of the twin screw; the extruder temperature is set as follows: 225°C in the feeding port area, 245°C in the plasticizing zone, 255°C in the metering zone, and 255°C in the die head; the screw speed is set to 150 rpm to maintain melt shearing and mixing; the melt is extruded through the die head, water-cooled, and pelletized to obtain composite material particles, which are polycarbonate composite materials.

[0042] Comparative Example 2 The difference from Example 3 is that the potassium titanate whiskers in this comparative example were not subjected to coupling treatment. This comparative example provides a polycarbonate composite material mainly prepared from the following components in parts by weight: 75 parts polycarbonate resin, 10 parts carbon fiber, 6 parts potassium titanate whiskers, 6 parts liquid crystal polymer, 2 parts toughening agent, 0.5 parts antioxidant, and 0.5 parts lubricant.

[0043] The preparation method of this polycarbonate composite material includes the following steps: S1. Raw material pretreatment: Vacuum dry polycarbonate resin at 80℃ for 4 hours and carbon fiber at 100℃ for 2 hours. After drying, weigh them according to the set ratio and set aside. Weigh potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant according to the set ratio and set aside. S2. Premixing: According to the set ratio, the polycarbonate resin, potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant and lubricant weighed in step S1 are placed in a high-speed mixer and mixed at room temperature for 5 minutes to obtain a premix. S3. Twin-screw extrusion granulation: The premixed material described in step S2 is added through the main feed port of a parallel co-rotating twin-screw extruder; the carbon fiber weighed in step S1 is added through the side feed port in the middle section of the twin screw; the extruder temperature is set as follows: 225°C in the feeding port area, 245°C in the plasticizing zone, 255°C in the metering zone, and 255°C in the die head; the screw speed is set to 150 rpm to maintain melt shearing and mixing; the melt is extruded through the die head, water-cooled, and pelletized to obtain composite material particles, which are polycarbonate composite materials. Comparative Example 3 Compared to Example 3, the ratio of coupled potassium titanate whiskers to liquid crystal polymer in this comparative example is changed from 6:6 to 3:7. This comparative example provides a polycarbonate composite material mainly prepared from the following components in parts by weight: 77 parts polycarbonate resin, 10 parts carbon fiber, 3 parts coupled potassium titanate whiskers, 7 parts liquid crystal polymer, 2 parts toughening agent, 0.5 parts antioxidant, and 0.5 parts lubricant.

[0044] The preparation method of this polycarbonate composite material includes the following steps: S1. Vacuum dry the polycarbonate resin at 80℃ for 4 hours and the carbon fiber at 100℃ for 2 hours. After drying, weigh them according to the set ratio and set aside. Weigh the coupling potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant according to the set ratio and set aside. In step S1, the preparation method of coupled potassium titanate whiskers includes the following steps: a solution is prepared by mixing deionized water and anhydrous ethanol at a volume ratio of 15:85 as a treatment solution, the pH is adjusted to 4-5 with acetic acid, and the coupling agent and potassium titanate whiskers are placed in the treatment solution. The liquid-solid ratio of the treatment solution to the potassium titanate whiskers is 20 mL: 1 g, and the mass of the coupling agent is 3% of the mass of the potassium titanate whiskers. The mixture is mechanically stirred at 60°C for 2 h. After the reaction is completed, the mixture is filtered, the filter cake is washed 2-3 times with anhydrous ethanol, and then dried at 120°C for 2 h to obtain coupled potassium titanate whiskers.

[0045] S2. Premix: Place the polycarbonate resin, coupled potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant weighed in step S1 into a high-speed mixer and mix at room temperature for 5 minutes to obtain a premix. S3. Twin-screw extrusion granulation: The premixed material described in step S2 is added from the main feed port of a parallel co-rotating twin-screw extruder; the carbon fiber weighed in step S1 is added through the side feed port in the middle section of the twin screw; the extruder temperature is set as follows: 225°C in the feeding port area, 245°C in the plasticizing zone, 255°C in the metering zone, and 255°C in the die head; the screw speed is set to 150 rpm to maintain melt shearing and mixing; the melt is extruded through the die head, water-cooled, and pelletized to obtain composite material particles, which are polycarbonate composite materials.

[0046] Standard test specimens were prepared from the carbonate composite materials of Examples 1-3 and Comparative Examples 1-3 above at a mold temperature of 90°C, an injection temperature of 270°C, and a holding pressure of 100MPa for subsequent testing.

[0047] The test results of tensile strength, flexural strength and notched impact strength of the polycarbonate composites of Examples 1-3 and Comparative Examples 1-3 are shown in Tables 1 and 2.

[0048] Table 1. Results of room temperature mechanical properties of different samples from Examples 1-3 and Comparative Examples 1-3

[0049] Table 2. Mechanical property test results of different samples from Examples 1-3 and Comparative Examples 1-3 at -60℃

[0050] As can be seen from Tables 1 and 2, the tensile strength, flexural strength and notched impact strength of Example 3 are higher than those of other samples, regardless of whether the environment is at room temperature or low temperature (-60℃). The comprehensive mechanical properties of Example 3 are the best, mainly because the coupling potassium titanate whiskers and the liquid crystal polymer in a specific ratio produce a synergistic toughening and strengthening effect.

[0051] Compared to Comparative Example 1 and Example 3, the tensile strength, flexural strength, and notched impact strength of the polycarbonate composite material decreased significantly at room temperature. The decrease in notched impact strength was particularly severe at low temperatures (-60°C), indicating that the liquid crystal polymer plays a crucial role in improving the strength and toughness of the polycarbonate composite material, especially in maintaining toughness at low temperatures. This is because the liquid crystal polymer forms a microfiber structure within the polycarbonate resin matrix, significantly enhancing and toughening the material.

[0052] Compared to Comparative Example 2 and Example 3, the notched impact strength dropped by 50% at room temperature and by approximately 61% at low temperature (-60°C). This indicates that the uncoupled potassium titanate whiskers have poor bonding with the polycarbonate resin matrix, becoming stress concentration points that easily lead to brittle fracture under impact, severely affecting toughness. At low temperature (-60°C), the tensile strength of Examples 1-3 after coupling treatment significantly increased to 107-129 MPa, while still maintaining good toughness of 21-28 kJ / m. 2 This further illustrates that coupled potassium titanate whiskers, as a rigid reinforcing phase, can effectively bridge cracks and induce plastic deformation of the matrix through good interfacial bonding, thereby absorbing a large amount of impact energy. Therefore, the present invention uses coupled potassium titanate whiskers to improve interfacial compatibility; otherwise, uncoupled potassium titanate whiskers would not only fail to provide reinforcement but would also cause the polycarbonate composite material to become brittle.

[0053] Compared to Example 3, Comparative Example 3 showed a decrease in tensile strength, flexural strength, and notched impact strength at both room temperature and low temperature (-60°C). This indicates that increasing the content of liquid crystal polymer and reducing the amount of coupled potassium titanate whiskers resulted in an inability to achieve optimal synergistic effects between excessive liquid crystal polymer and insufficient coupled potassium titanate whiskers. In Example 3, the optimal weight ratio of coupled potassium titanate whiskers to liquid crystal polymer was 6:6. This also demonstrates that coupled potassium titanate whiskers, as the main toughening and reinforcing agent, work synergistically with an appropriate amount of liquid crystal polymer to provide auxiliary reinforcement and compatibilization. An imbalance in the ratio of the two (as in Comparative Example 3) or the absence of either (as in Comparative Example 1) leads to a decrease in performance.

[0054] Figure 1 The image shows a scanning electron microscope (SEM) image and elemental analysis diagram of the polycarbonate composite material provided in Example 3 of this invention.

[0055] Figure 1(a) is a high-magnification close-up scanning electron microscope image. It can be seen that the liquid crystal polymer is in the form of long, thin fibers, intertwined and entangled, similar to the structure of a "bird's nest" or non-woven fabric. This high aspect ratio morphology is the physical basis for its ability to strengthen and toughen the structure.

[0056] Figure 1 (b) is a scanning electron microscope (SEM) image of the overall texture of the fracture surface. The surface is extremely rough, exhibiting numerous fiber tears and layered structures. This rough surface indicates that the material underwent complex crack propagation and deflection during fracture, absorbing a significant amount of impact energy. The absence of large, smooth, mirror-like areas suggests that the material did not experience typical brittle fracture. The complex morphology indicates that the material underwent severe plastic deformation during fracture.

[0057] Figure 1 (c) is a side-view scanning electron microscope image of the fracture surface, which shows an irregular cross-section with large tear ridges and deep pits. This confirms that the polycarbonate composite material prepared in Example 3 has extremely high impact toughness, since brittle materials usually have smooth fracture surfaces.

[0058] Figure 1 As shown in (d), many micropores and short fibrous protrusions are clearly visible in the matrix.

[0059] Figure 1 (e) shows the microscopic interface under high magnification. The matrix surface is covered with tiny pits and fine rod-like structures, which are potassium titanate whiskers. After coupling treatment, the potassium titanate whiskers are very uniformly dispersed in the matrix without obvious agglomeration. Many tiny pores in this image are gases released during injection molding due to the high temperature, resulting in numerous tiny, dense bubbles (honeycomb structure). These phenomena confirm that Example 3 successfully constructed a two-scale reinforcement system of carbon fiber and potassium titanate whiskers. The use of the coupling agent ensures a tight bond between the potassium titanate whiskers and the matrix, allowing stress to be transferred through the interface under load, thus synergistically reinforcing and toughening the matrix with the toughening agent.

[0060] Figure 1 (f) is an EDS elemental analysis descriptive diagram, with color spots showing the distribution of different elements in the microscopic region. Red represents carbon (C), originating from the polycarbonate resin matrix, carbon fibers, liquid crystal polymers, toughening agents, etc., and is fully covered by the background. Green represents oxygen (O), which is also relatively evenly distributed. Cyan represents titanium (Ti), and purple represents potassium (K). These bright spots are evenly scattered throughout the image, proving that potassium titanate whiskers are uniformly dispersed in the matrix without agglomeration, which is a characteristic element of potassium titanate whiskers. Yellow represents silicon (Si), originating from the silane coupling agent. The presence of Si, and its roughly overlapping distribution with that of Ti and K, directly proves that the silane coupling agent was successfully coated on the surface of the potassium titanate whiskers.

[0061] Table 3 Elemental analysis of the sample from Example 3

[0062] Table 3 is an elemental analysis table of the sample from Example 3. The composition and content of each element can be seen from the figure.

[0063] Combined with Table 3 and Figure 1 (g) The elemental energy spectrum shows that carbon has the strongest peak, indicating it is the main matrix component; titanium and potassium show distinct characteristic peaks, confirming the presence of potassium titanate whiskers. A clear Si peak is also present, further confirming the presence of the silane coupling agent.

[0064] Figure 2 Scanning electron microscope image of the polycarbonate composite material provided for Comparative Example 1.

[0065] Figure 2 (a) The macroscopic fracture morphology is visible, with a certain degree of roughness and obvious layered tearing texture. Compared with the previous Example 3, the degree of undulation of its fracture surface may be relatively small, and the texture direction is relatively uniform. This demonstrates the fracture path of the pure polycarbonate resin matrix after impact. Although polycarbonate itself has a certain degree of toughness, the crack propagation path is relatively direct in the absence of liquid crystal polymer microfibers to hinder crack propagation.

[0066] Figure 2 (b) shows the surface of the spline, where it can be seen that the injection direction is from left to right.

[0067] Figure 2 (c) It can be seen that some fibers protrude from the matrix surface, while others are broken. There are certain gaps at the connection between the fiber roots and the matrix, which is the key reason for the poor mechanical properties (especially impact toughness) of the composite material.

[0068] Figure 3 Scanning electron microscope image of the polycarbonate composite material provided for Comparative Example 2.

[0069] Figure 3 In (a), the carbon fibers are clearly visible, along with the large, deep pores left after the fibers were pulled out. The matrix surface appears relatively "dry." This indicates that the matrix did not undergo large-scale plastic deformation before fracture.

[0070] Figure 3 (b) Although the fracture surface exhibits a certain degree of roughness, its texture appears looser compared to Example 3. The crack propagation path does not seem to be strongly hindered, which generally means that the material consumes less energy upon fracture, i.e., it has poor toughness.

[0071] Figure 3(c) The image is filled with numerous tiny, round holes. The inner walls and edges of these holes are very smooth and clean. This means that there is almost no chemical bonding or physical entanglement between the whiskers and the polycarbonate matrix. This is due to the numerous tiny air bubbles caused by the evaporation of moisture in the material during the high temperature of the injection molding process.

[0072] Figure 4 Scanning electron microscope image of the polycarbonate composite material provided for Comparative Example 3.

[0073] Figure 4 (a) The fracture surface exhibits an uneven morphology with numerous micropores and residual short fibers or whisker-like objects, and fine filler distribution can be observed. Due to the high content of liquid crystal polymer (7%) and the low content of coupled potassium titanate whiskers (3%), the pores in the image may be more due to the shedding of the liquid crystal polymer phase or the failure to form a good microfiber network. It is difficult to observe the dense, overlapping whisker-microfiber synergistic network as in Example 3. This confirms the "negative synergistic effect," where excessive liquid crystal polymer agglomerates into spheres, while the small amount of potassium titanate whiskers cannot effectively link these reinforcing phases.

[0074] Figure 4 (b) The presence of large-area color aggregation in the cyan patches indicates that the potassium titanate whiskers have agglomerated. The large agglomerated particles cannot effectively transfer load like individual whiskers under stress; instead, they become huge impurity points, easily initiating cracks within or at the edges of the agglomerates. Some whiskers are locked within the agglomerates and cannot contact the matrix, resulting in a significant reduction in the number of individual whiskers that actually provide reinforcement. This further illustrates that the performance degradation is not due to poor interfacial chemical bonding (as in Comparative Example 2), but rather to an improper physical ratio of the liquid crystal polymer to the coupled potassium titanate whiskers.

[0075] Table 4 Elemental analysis table for Comparative Example 3

[0076] The elemental analysis in Table 4 reflects the main components. The detection of approximately 2% silicon further confirms the successful introduction of the coupling agent. The presence of Ti and K elements confirms the presence of potassium titanate whiskers.

[0077] Figure 5 The TGA diagram is of the polycarbonate composite material provided in Example 3.

[0078] Depend on Figure 5The green TG curve shows that the sample's mass remained essentially constant before 400℃, with no significant thermal weight loss. TGA data confirms that the formulation in Example 3 exhibits extremely high thermal stability within the processing temperature range, fully meeting the process requirements of twin-screw extrusion and injection molding, and will not suffer performance degradation due to high-temperature degradation. The purple TG curve shows that the maximum thermal decomposition rate peak of this material occurs at 489.7℃. This decomposition temperature is very high. This indicates that 6% coupled potassium titanate whiskers and 6% liquid crystal polymer, in conjunction with 10% carbon fiber, construct a stable synergistic network. This multiphase structure may effectively suppress the thermal motion and breakage of polymer molecular chains, thereby significantly improving the overall heat resistance of the composite material. The final residual mass is 28.70%.

[0079] Figure 6 TGA diagram of the polycarbonate composite material provided for Comparative Example 3.

[0080] Depend on Figure 6 The purple DTG curve shows that the decomposition peak of this sample occurs at 460.0°C. Comparative Example 3 contains 3% coupled potassium titanate whiskers and 7% liquid crystal polymer. Combined with the agglomeration observed in the previous microstructure analysis, this low thermal stability further confirms the extremely poor compatibility at this ratio. The green TG curve shows that the material remains stable before 400°C, with no significant weight loss. The final residual mass is 30.82%.

[0081] Figure 7 The image shows the FTIR plot of the polycarbonate composite material provided in Example 3.

[0082] Depend on Figure 7 As can be seen, the infrared spectrum exhibits typical characteristics of a polycarbonate-based system. The spectrum clearly shows all the characteristic functional groups of the polycarbonate and liquid crystal polymer system, with no degradation peaks. This confirms that during the blending process of this complex multi-component system, the components remain chemically stable, and no side reactions leading to polymer degradation occur, providing a chemical basis for the excellent mechanical properties.

[0083] It should be noted that the specific embodiments are merely representative examples of the present invention, and the technical solution of the present invention is obviously not limited to the above embodiments, and there can be many variations. Those skilled in the art who obtain the present invention based on its explicit disclosure or without objection from the written description should consider it to be within the scope of protection of this patent.

Claims

1. A polycarbonate composite material, characterized in that, It is mainly prepared from the following components in parts by weight: 70-80 parts of polycarbonate resin, 8-12 parts of carbon fiber, 6-14 parts of coupled potassium titanate whiskers, 2-8 parts of liquid crystal polymer, 1-2 parts of toughening agent, 0.5-1 part of antioxidant, and 0.5-1 part of lubricant.

2. The polycarbonate composite material according to claim 1, characterized in that, The melt flow rate (MFR) of the polycarbonate resin is 5–15 g / 10 min at 300°C and 1.2 kg.

3. The polycarbonate composite material according to claim 1, characterized in that, The carbon fiber is short-cut carbon fiber with a length of 3mm to 6mm.

4. The polycarbonate composite material according to claim 1, characterized in that, The coupled potassium titanate whiskers are obtained by surface treatment with a coupling agent; the coupling agent is any one of silane coupling agents, titanate coupling agents, aluminate coupling agents, and phosphate coupling agents.

5. The polycarbonate composite material according to claim 1, characterized in that, The antioxidant is a mixture of any two of antioxidants 1010, 168, 3114, and 626.

6. The polycarbonate composite material according to claim 1, characterized in that, The lubricant is selected from at least one of fatty acid ester lubricants, fatty acid amide lubricants, oxidized polyethylene wax lubricants, or polytetrafluoroethylene wax lubricants.

7. The method for preparing the polycarbonate composite material according to any one of claims 1-6, characterized in that, The preparation method includes the following steps: S1. Raw material drying and weighing: Dry the polycarbonate resin and carbon fiber separately under vacuum, and weigh them according to the set ratio for later use; weigh the coupling potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant according to the set ratio for later use. S2. Premixing: Place the polycarbonate resin, coupled potassium titanate whiskers, liquid crystal polymer, toughening agent, antioxidant, and lubricant weighed in step S1 into a high-speed mixer and mix at room temperature for 3-5 minutes to obtain a premix. S3. Twin-screw extrusion granulation: The premixed material described in step S2 is added from the main feed port of a parallel co-rotating twin-screw extruder; the carbon fiber weighed in step S1 is added through the side feed port in the middle section of the twin screw; the extruder temperature is set; the screw speed is set to 150-200 rpm to maintain melt shearing and mixing; the melt is extruded through the die head, water-cooled, and pelletized to obtain composite material particles, which are polycarbonate composite materials.

8. The method for preparing the polycarbonate composite material according to claim 7, characterized in that, In step S1, the preparation method of coupled potassium titanate whiskers includes the following steps: a solution is prepared by mixing deionized water and anhydrous ethanol at a volume ratio of 15:85 as a treatment solution, the pH is adjusted to 4-5, the coupling agent and potassium titanate whiskers are placed in the treatment solution, the liquid-solid ratio of the treatment solution to the potassium titanate whiskers is (10-20) mL:1g, the mass of the coupling agent is 2%-3% of the mass of the potassium titanate whiskers, the mixture is mechanically stirred at a constant temperature of 60-80℃ for 2-4 hours, after the reaction is completed, the mixture is filtered, the filter cake is washed 2-3 times with anhydrous ethanol, and then dried at a temperature of 100-120℃ for 2-4 hours to obtain coupled potassium titanate whiskers.

9. The method for preparing the polycarbonate composite material according to claim 7, characterized in that, In step S3, the extruder temperature is set as follows: the feeding port area is 220-230℃, the plasticizing area is 240-250℃, the metering area is 250-255℃, and the die head temperature is 250-260℃.

10. The application of the polycarbonate composite material as described in any one of claims 1-7 or the polycarbonate composite material prepared by the preparation method as described in claims 8-9 in automotive interiors, drone shells, robot exoskeletons, cryogenic storage devices, electronics and electrical appliances, home appliances, aerospace, sports equipment, and medical devices.

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