Preparation method of polyphenylene sulfide composite material

Abstract

The invention relates to a preparation method of a polyphenylene sulfide composite material, and belongs to the technical field of polymer composite material emerging and preparation, and the preparation method comprises the following steps: carrying out co-hydrolytic polycondensation on tetramethoxysilane, 3, 3, 3-trifluoropropylmethyldimethoxysilane, 4, 4-bis (dimethoxymethylsilyl) biphenyl and methyldimethoxysilane in tetrahydrofuran under the catalysis of trifluoromethanesulfonic acid; a fluorine-containing polysiloxane intermediate is obtained by neutralizing and removing impurities, then the fluorine-containing polysiloxane intermediate and allyl glycidyl ether are subjected to hydrosilylation in methylbenzene under the catalysis of Karstedt, a solvent is removed, a reactive modifier is obtained, finally, 5-25 parts of the modifier, 70-95 parts of polyphenylene sulfide, 0.05-0.5 part of a grafting accelerant and 0.1-1 part of an antioxidant are evenly mixed, and the composite material is prepared through melt extrusion and pelletizing. According to the invention, the compatibility between siloxane and a polyphenylene sulfide matrix is greatly improved, and the problem of phase separation easily generated by simple physical blending is avoided.

Description

Technical Field

[0001] This invention relates to the emerging and preparation field of polymer composite materials, specifically a method for preparing polyphenylene sulfide composite materials. Background Technology

[0002] Polyphenylene sulfide (PPS) is an engineering resin with excellent molding and processing properties, and it has important applications in fields such as 5G high-frequency communication and advanced driver assistance systems for new energy vehicles. However, from the perspective of the inherent physical properties of PPS, when used as a core component such as millimeter-wave radar domes, there is an inherent contradiction between its extreme brittleness and high polarization loss in high-frequency communication, and there are still many shortcomings. To address the mechanical and high-frequency electromagnetic problems of PPS materials, modification is an effective way to overcome its performance defects. Traditional physical blending modification schemes often suffer from kinetic mismatch between components and lack of chemical covalent anchoring, which easily leads to a significant drop in the material's heat deformation temperature and the formation of micropores at the phase interface, thereby causing severe electromagnetic wave scattering and increased dielectric loss. At present, an effective means of preparing high-performance PPS composite materials is to synthesize reactive fluorinated hyperbranched polysiloxane modifiers through molecular structure design, and to use reactive melt extrusion to allow the modifier to undergo an in-situ chemical grafting reaction with the matrix, constructing a rigid-flexible nanoscale microphase separation structure, thereby synergistically overcoming the technical bottlenecks of brittleness and polarization loss.

[0003] The information disclosed in the background section is only for enhancing the understanding of the background of this invention and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing polyphenylene sulfide composite materials to solve the problems mentioned in the background art.

[0005] The technical solution of the present invention includes: S1, adding tetramethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, 4,4-bis(dimethoxymethylsilyl)biphenyl and methyldimethoxysilane to tetrahydrofuran and mixing them; adding an aqueous solution containing trifluoromethanesulfonic acid dropwise at a rate of 1-5 drops / second under stirring at 200-500 rpm and carrying out a co-hydrolysis condensation reaction under reflux conditions; after the reaction is completed, adding sodium bicarbonate at a molar amount of 1.1-1.5 times relative to trifluoromethanesulfonic acid to neutralize to neutral; filtering and distilling under reduced pressure at 60-90°C for 2-4 hours to remove solvent and low molecular weight byproducts to obtain a fluorinated polysiloxane intermediate;

[0006] S2, the fluorinated polysiloxane intermediate obtained in step S1 is mixed with allyl glycidyl ether, toluene is added, nitrogen gas is introduced for protection, Karstedt catalyst is added and heated to carry out hydrosilylation reaction, after the reaction is completed, the solvent and unreacted allyl glycidyl ether are removed by rotary evaporation under reduced pressure to obtain reactive fluorinated hyperbranched polysiloxane modifier.

[0007] S3. By weight, take 70-95 parts of polyphenylene sulfide resin and dry it in a vacuum drying equipment. Then, mix the dried polyphenylene sulfide resin with 5-25 parts of reactive fluorinated hyperbranched polysiloxane modifier, 0.05-0.5 parts of grafting accelerator and 0.1-1.0 parts of antioxidant obtained in step S2 in a mixer to obtain a premix.

[0008] S4. The premix obtained in step S3 is fed into a twin-screw extruder for reactive melt extrusion. The extruded material is cooled in a water tank, air-dried, and pelletized to obtain a polyphenylene sulfide composite material.

[0009] Further, in step S1, the molar ratio of tetramethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, 4,4-bis(dimethoxymethylsilyl)biphenyl and methyldimethoxysilane is 1:6:2:4.

[0010] Further, in step S1, the mass fraction of trifluoromethanesulfonic acid in the aqueous solution containing trifluoromethanesulfonic acid is 0.5 wt%; the reaction temperature of the co-hydrolysis condensation reaction is 40-60℃, and the reaction time is 4-8 hours.

[0011] Further, in step S2, the amount of allyl glycidyl ether added is 1.5 times the molar amount of silane-hydrogen bonds in the fluorinated polysiloxane intermediate; the platinum content in the Karstedt catalyst is 10~50 ppm; the reaction temperature of the hydrosilylation reaction is 80-95℃, and the reaction time is 4-6 hours.

[0012] Further, in step S3, the polyphenylene sulfide resin is a linear or cross-linked polyphenylene sulfide with thiol end groups, and its melt index is 20~200g / 10min at 315.6℃ and 5kg; the drying temperature of the vacuum drying equipment is 120℃ and the drying time is 4 hours.

[0013] Further, in step S3, the grafting promoter is selected from quaternary phosphonium salts or imidazole compounds; the antioxidant is a complex of hindered phenolic antioxidants and phosphite antioxidants.

[0014] Furthermore, the grafting promoter is tetraphenylphosphonium bromide or 2-ethyl-4-methylimidazole.

[0015] Further, in step S4, the twin-screw extruder is a co-rotating twin-screw extruder, and the temperature settings of each zone are as follows: feeding section 260-280℃, melt reaction section 285-315℃, metering section 290-300℃, and die head 290℃; the screw speed of the twin-screw extruder is 200-400 rpm.

[0016] This invention provides an improved method for preparing polyphenylene sulfide composite materials, which has the following improvements and advantages compared with the prior art:

[0017] 1. This invention prepares a reactive fluorinated hyperbranched polysiloxane modifier by hydrosilylation reaction of allyl glycidyl ether with a fluorinated polysiloxane intermediate. This modifier is reactive and can react with polyphenylene sulfide resins with thiol end groups. Furthermore, under the efficient catalysis of a grafting accelerator, the modifier is effectively grafted onto the polyphenylene sulfide macromolecular chain. This chemical bonding greatly improves the compatibility between the siloxane and the polyphenylene sulfide matrix, avoiding the phase separation problem that easily occurs in simple physical blending.

[0018] 2. This invention uses tetramethoxysilane and other multifunctional silanes as raw materials to participate in co-hydrolysis and polycondensation reactions, successfully constructing hyperbranched polysiloxane structures. Hyperbranched polysiloxanes have special spatial structures. When used as modifiers and reacted with polyphenylene sulfide resin in a twin-screw extruder for melt extrusion, they can effectively reduce the friction between macromolecular chains and significantly improve the melt flowability of polyphenylene sulfide resin without damaging the main structure of the matrix.

[0019] 3. In the process of preparing fluorinated polysiloxane intermediates, this invention innovatively introduces 4,4-bis(dimethoxymethylsilyl)biphenyl monomer; the biphenyl structure has excellent rigidity and thermal stability. The introduction of this special structure effectively compensates for the defects that conventional polysiloxane flexible segments may lead to a decrease in the heat resistance and mechanical strength of composite materials, so that the final polyphenylene sulfide composite material has excellent toughness, rigidity and high temperature resistance.

[0020] 4. This invention uses 3,3,3-trifluoropropylmethyldimethoxysilane as a co-reacting monomer to successfully introduce fluorine-containing groups such as trifluoropropyl into the skeleton of the hyperbranched polysiloxane modifier; after reactive extrusion grafting, the fluorine-containing segments can be uniformly distributed in the polyphenylene sulfide matrix or enriched on the material surface, thereby endowing the polyphenylene sulfide composite material with better special surface properties and more outstanding physicochemical stability.

[0021] 5. Before reactive melt extrusion, this invention scientifically proportions a complex of hindered phenolic antioxidants and phosphite antioxidants in the premix. The synergistic effect of the dual antioxidants can effectively capture free radicals generated during processing and decompose hydroperoxides, greatly inhibiting the thermo-oxidative degradation and cross-linking side reactions of polyphenylene sulfide resin under high-temperature melting and shearing conditions, ensuring the stability of the material's color and the high efficiency, continuity, and controllability of the preparation process. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0023] Example 1:

[0024] A method for preparing a polyphenylene sulfide composite material includes the following steps:

[0025] S1, tetramethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, 4,4-bis(dimethoxymethylsilyl)biphenyl and methyldimethoxysilane are added to tetrahydrofuran and mixed. Under stirring at 200-500 rpm, an aqueous solution containing trifluoromethanesulfonic acid is added dropwise at a rate of 1-5 drops / second, and a co-hydrolysis condensation reaction is carried out under reflux conditions. After the reaction is completed, sodium bicarbonate is added in a molar amount of 1.1-1.5 times relative to trifluoromethanesulfonic acid to neutralize to neutral. After filtration, the solvent and low molecular weight byproducts are removed by vacuum distillation at 60-90℃ for 2-4 hours to obtain a fluorinated polysiloxane intermediate.

[0026] S2, the fluorinated polysiloxane intermediate obtained in step S1 is mixed with allyl glycidyl ether, toluene is added, nitrogen gas is introduced for protection, Karstedt catalyst is added and the temperature is raised to carry out hydrosilylation reaction. After the reaction is completed, the solvent and unreacted allyl glycidyl ether are removed by rotary evaporation under reduced pressure to obtain a reactive fluorinated hyperbranched polysiloxane modifier.

[0027] S3. By weight, take 70-95 parts of polyphenylene sulfide resin and dry it in a vacuum drying equipment. Then, mix the dried polyphenylene sulfide resin with 5-25 parts of reactive fluorinated hyperbranched polysiloxane modifier, 0.05-0.5 parts of grafting accelerator and 0.1-1.0 parts of antioxidant obtained in step S2 in a mixer to obtain a premix.

[0028] S4, the premix obtained in step S3 is fed into a twin-screw extruder for reactive melt extrusion. The extruded material is cooled in a water bath, air-dried, and pelletized to obtain a polyphenylene sulfide composite material; in step S1, the molar ratio of tetramethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, 4,4-bis(dimethoxymethylsilyl)biphenyl and methyldimethoxysilane is 1:6:2:4;

[0029] In step S1, the mass fraction of trifluoromethanesulfonic acid in the aqueous solution containing trifluoromethanesulfonic acid is 0.5 wt%; the reaction temperature of the co-hydrolysis polycondensation reaction is 40-60℃, and the reaction time is 4-8 hours.

[0030] In step S2, the amount of allyl glycidyl ether added is 1.5 times the molar amount of silane bonds in the fluorinated polysiloxane intermediate; the platinum content in the Karstedt catalyst is 10~50 ppm; the reaction temperature of the hydrosilylation reaction is 80-95℃, and the reaction time is 4-6 hours.

[0031] In step S3, the polyphenylene sulfide resin is a linear or cross-linked polyphenylene sulfide with thiol end groups, and its melt index is 20~200g / 10min at 315.6℃ and 5kg; the drying temperature of the vacuum drying equipment is 120℃ and the drying time is 4 hours.

[0032] In step S3, the grafting promoter is selected from quaternary phosphonium salt compounds or imidazole compounds; the antioxidant is a complex of hindered phenolic antioxidant and phosphite antioxidant; the grafting promoter is tetraphenylphosphonium bromide or 2-ethyl-4-methylimidazole.

[0033] In step S4, the twin-screw extruder is a co-rotating twin-screw extruder, and the temperature settings for each zone are as follows: feeding section 260-280℃, melt reaction section 285-315℃, metering section 290-300℃, and die head 290℃; the screw speed of the twin-screw extruder is 200-400 rpm.

[0034] This embodiment provides a method for preparing a polyphenylene sulfide composite material, aiming to resolve the intrinsic contradiction between the inherent extreme brittleness of conventional matrix resins and the polarization loss in high-frequency communication. This preparation method synthesizes a multifunctional reactive fluorinated hyperbranched polysiloxane modifier through molecular structure design. In a reactor equipped with a condenser and a mechanical stirrer, 0.1 mol of tetramethoxysilane, 0.6 mol of trifluoropropylmethyldimethoxysilane, 0.2 mol of 4,4-bis(dimethoxymethylsilyl)biphenyl, and 0.4 mol of methyldimethoxysilane are added to 500 mL of tetrahydrofuran and mixed. The specific stoichiometric ratio ensures the kinetic matching between the hyperbranched core and the rigid nodes.

[0035] Under forced stirring at a speed of 350 rpm, an aqueous solution containing 0.5% by weight of trifluoromethanesulfonic acid was slowly added at a dropping rate of 3 drops per second. This dropping rate effectively controlled the local concentration overload of the silanol polycondensation. The co-hydrolysis polycondensation reaction was carried out at 50 degrees Celsius for 6 hours. After the reaction was completed, sodium bicarbonate was added in a ratio of 1.3 times the molar amount of trifluoromethanesulfonic acid to neutralize the solution. The solution was filtered and then distilled under reduced pressure at 75 degrees Celsius for 3 hours to remove the solvent and low molecular weight byproducts, resulting in a fluorinated polysiloxane intermediate with a purity greater than 99% and a total yield of 92% and a surface rich in silane-hydrogen bonds.

[0036] In the subsequent terminal epoxy grafting reaction, the fluorinated polysiloxane intermediate was mixed with allyl glycidyl ether at 1.5 times the molar amount of silane-hydrogen bonds, toluene solvent was added and nitrogen gas was introduced for protection. Karstedt catalyst with a platinum content of 30 ppm was added and the temperature was raised to 88 degrees Celsius to carry out a hydrosilylation reaction for 5 hours. The reaction endpoint was determined by the complete disappearance of the Si-H characteristic peak at 2150 cm⁻¹ by infrared spectroscopy. After removing the solvent by rotary evaporation under reduced pressure, a reactive fluorinated hyperbranched polysiloxane modifier with a purity of 98% and a yield of 95% was obtained. Its 1H NMR spectrum confirmed the successful grafting of terminal epoxy groups and the formation of hyperbranched structure. In the matrix construction stage of the composite material, 85 parts by weight of linear polyphenylene sulfide resin with end groups containing mercapto groups and a melt index of 50 g / 10 min at 315.6 degrees Celsius and 5 kg load was placed in a vacuum drying equipment at 120 degrees Celsius and dried for 4 hours to eliminate the interference of moisture on subsequent melt grafting.

[0037] The dried polyphenylene sulfide resin was mixed with 15 parts by weight of a reactive fluorinated hyperbranched polysiloxane modifier, 0.2 parts by weight of a tetraphenylphosphonium bromide grafting accelerator, and 0.5 parts by weight of an antioxidant composed of hindered phenols and phosphites in equal proportions in a high-speed mixer to obtain a premix. In the final reactive melt extrusion step, the premix was fed into a co-rotating twin-screw extruder, with the temperatures of each zone precisely set as follows: 270 degrees Celsius in the feeding section, 300 degrees Celsius in the melt reaction section, and 295 degrees Celsius in the metering section. With the die head at 290 degrees Celsius and the screw speed maintained at 300 rpm, under the synergistic effect of high temperature and strong shear and grafting accelerator, the epoxy groups at the end of the modifier and the thiol groups at the end of the polyphenylene sulfide molecular chain undergo an in-situ ring-opening grafting reaction, achieving covalent anchoring and self-assembly into a nanoscale core-shell microphase separation structure. The extruded material is cooled in a water bath, air-dried, and pelletized to obtain the target composite material. This embodiment demonstrates the excellent dispersibility of the modifier in the matrix without macroscopic agglomeration, effectively locking the tensile modulus of the material.

[0038] Example 2:

[0039] S1, tetramethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, 4,4-bis(dimethoxymethylsilyl)biphenyl and methyldimethoxysilane are added to tetrahydrofuran and mixed. Under stirring at 200-500 rpm, an aqueous solution containing trifluoromethanesulfonic acid is added dropwise at a rate of 1-5 drops / second, and a co-hydrolysis condensation reaction is carried out under reflux conditions. After the reaction is completed, sodium bicarbonate is added in a molar amount of 1.1-1.5 times relative to trifluoromethanesulfonic acid to neutralize to neutral. After filtration, the solvent and low molecular weight byproducts are removed by vacuum distillation at 60-90℃ for 2-4 hours to obtain a fluorinated polysiloxane intermediate.

[0040] S2, add Karstedt catalyst and heat to carry out hydrosilylation reaction; S4, feed the premix obtained in step S3 into a twin-screw extruder for reactive melt extrusion; in step S1, the reaction temperature of the co-hydrolysis polycondensation reaction is 40-60℃ and the reaction time is 4-8 hours.

[0041] In step S2, the platinum content in the Karstedt catalyst is 10-50 ppm; the reaction temperature of the hydrosilylation reaction is 80-95℃, and the reaction time is 4-6 hours; in step S4, the temperature settings of each zone of the twin-screw extruder are: feeding zone 260-280℃, melting reaction zone 285-315℃, metering zone 290-300℃; the screw speed of the twin-screw extruder is 200-400 rpm.

[0042] This embodiment verifies the boundary conditions of a method for preparing a polyphenylene sulfide composite material, focusing on the reaction kinetics evolution under high shear and high temperature thermal processes. When preparing the fluorinated polysiloxane intermediate, the stirring speed was increased to 500 rpm, the dropping rate was set to 5 drops per second, and the co-hydrolysis polycondensation reaction was carried out at 60 degrees Celsius for 8 hours. After the reaction, sodium bicarbonate with a molar amount of 1.5 times that of trifluoromethanesulfonic acid was added to neutralize to neutrality, and the vacuum distillation temperature was set at 90 degrees Celsius for 4 hours to verify the integrity of the hyperbranched network skeleton under violent reaction conditions.

[0043] In the hydrosilylation reaction stage, the platinum content of the Karstedt catalyst was increased to 50 ppm, the reaction temperature was raised to 95 degrees Celsius, and the reaction was carried out for 6 hours. In the composite material extrusion stage, the premix consisted of 70 parts by weight of polyphenylene sulfide resin with a melt index of 200 g / 10 min, 25 parts by weight of modifier, 0.5 parts by weight of 2-ethyl-4-methylimidazolium grafting accelerator, and 1.0 part by weight of antioxidant. The temperature profile of the twin-screw extruder was shifted upwards as a whole, with the feeding section set at 280 degrees Celsius, the melt reaction section at 315 degrees Celsius, the metering section at 300 degrees Celsius, and the screw speed reaching the limit condition of 400 rpm.

[0044] The high shear field effectively promoted in-situ nanophase separation in high-viscosity systems. Although the high concentration of modifier increased the steric hindrance effect of the interfacial reaction, high-density chemical bonding was still achieved through extreme thermomechanical input, verifying the robustness of this technical solution under extreme processing windows.

[0045] Example 3:

[0046] S1, tetramethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, 4,4-bis(dimethoxymethylsilyl)biphenyl and methyldimethoxysilane are added to tetrahydrofuran and mixed. Under stirring at 200-500 rpm, an aqueous solution containing trifluoromethanesulfonic acid is added dropwise at a rate of 1-5 drops / second, and a co-hydrolysis condensation reaction is carried out under reflux conditions. After the reaction is completed, sodium bicarbonate is added in a molar amount of 1.1-1.5 times relative to trifluoromethanesulfonic acid to neutralize to neutral. After filtration, the solvent and low molecular weight byproducts are removed by vacuum distillation at 60-90℃ for 2-4 hours to obtain a fluorinated polysiloxane intermediate.

[0047] S2, add Karstedt catalyst and raise the temperature to initiate a hydrosilylation reaction; S4, feed the premix obtained in step S3 into a twin-screw extruder for reactive melt extrusion; in step S1, the reaction temperature of the co-hydrolysis polycondensation reaction is 40-60℃, and the reaction time is 4-8 hours; in step S2, the platinum content in the Karstedt catalyst is 10-50 ppm; the reaction temperature of the hydrosilylation reaction is 80-95℃, and the reaction time is 4-6 hours; in step S4, the temperature settings of each zone of the twin-screw extruder are: feeding zone 260-280℃, melt reaction zone 285-315℃, metering zone 290-300℃; the screw speed of the twin-screw extruder is 200-400 rpm;

[0048] This embodiment aims to explore the feasibility of in-situ construction of a polyphenylene sulfide composite material under mild conditions to reduce side reactions caused by thermal hysteresis. In the construction of the hyperbranched network, the rotation speed was reduced to 200 rpm, and the aqueous solution was added dropwise at a very slow rate of 1 drop per second. The co-hydrolysis and polycondensation reaction was carried out at a low temperature of 40 degrees Celsius for 4 hours. After the reaction, sodium bicarbonate was added at a molar amount of 1.1 times relative to trifluoromethanesulfonic acid to neutralize to neutral, and vacuum distillation was carried out at 60 degrees Celsius for 2 hours. In the hydrosilylation reaction, the platinum content of the catalyst was reduced to 10 ppm, and the reaction temperature was maintained at 80 degrees Celsius for 4 hours.

[0049] The premixed system uses 95 parts by weight of high-viscosity polyphenylene sulfide resin with a melt index of only 20 g / 10 min and 5 parts by weight of modifier, supplemented with 0.05 parts by weight of accelerator and 0.1 parts by weight of antioxidant; the extruder parameters are set as follows: feeding section 260 degrees Celsius, melting reaction section 285 degrees Celsius, metering section 290 degrees Celsius, and screw speed 200 rpm; although the low shear and low temperature environment reduces the reaction rate of ring-opening grafting, it gives the rigid and flexible molecular chain segments more sufficient relaxation time, allowing the trifluoropropyl segments to fully expand in the free volume, effectively suppressing the polarization loss of high-frequency electromagnetic waves at the molecular level.

[0050] Example 4:

[0051] S1, tetramethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, 4,4-bis(dimethoxymethylsilyl)biphenyl and methyldimethoxysilane are added to tetrahydrofuran and mixed. Under stirring at 200-500 rpm, an aqueous solution containing trifluoromethanesulfonic acid is added dropwise at a rate of 1-5 drops / second, and a co-hydrolysis condensation reaction is carried out under reflux conditions. After the reaction is completed, sodium bicarbonate is added in a molar amount of 1.1-1.5 times relative to trifluoromethanesulfonic acid to neutralize to neutral. After filtration, the solvent and low molecular weight byproducts are removed by vacuum distillation at 60-90℃ for 2-4 hours to obtain a fluorinated polysiloxane intermediate.

[0052] S2, add Karstedt catalyst and raise the temperature to initiate a hydrosilylation reaction; S4, feed the premix obtained in step S3 into a twin-screw extruder for reactive melt extrusion; in step S1, the reaction temperature of the co-hydrolysis polycondensation reaction is 40-60℃, and the reaction time is 4-8 hours; in step S2, the platinum content in the Karstedt catalyst is 10-50 ppm; the reaction temperature of the hydrosilylation reaction is 80-95℃, and the reaction time is 4-6 hours; in step S4, the temperature settings of each zone of the twin-screw extruder are: feeding zone 260-280℃, melt reaction zone 285-315℃, metering zone 290-300℃; the screw speed of the twin-screw extruder is 200-400 rpm;

[0053] This embodiment represents a further optimization of the preparation method of a polyphenylene sulfide composite material, focusing on compatibility control under medium to high loads. During the synthesis of the intermediate, a rotation speed of 400 rpm and a dropping rate of 4 drops per second were used. The co-hydrolysis and polycondensation reaction was carried out at 55°C for 7 hours. After the reaction, sodium bicarbonate (1.4 times the molar amount of trifluoromethanesulfonic acid) was added to neutralize the mixture, and vacuum distillation was performed at 80°C for 3.5 hours. In the hydrosilylation stage, a 40 ppm platinum catalyst was used at 92°C for 5.5 hours.

[0054] The formulation system contains 75 parts by weight of resin with a melt index of 150 g / 10 min and 20 parts by weight of modifier. The extruder temperature is set to 275 degrees Celsius in the feeding section and 310 degrees Celsius in the melt reaction section, with a rotation speed of 350 rpm. The moderately increased reaction driving force accelerates the grafting efficiency of the terminal epoxy groups and effectively blocks the microcrack propagation path. This embodiment verifies the excellent adaptability of the material to impact energy absorption under a relatively high formulation ratio.

[0055] Example 5:

[0056] S1, tetramethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, 4,4-bis(dimethoxymethylsilyl)biphenyl and methyldimethoxysilane are added to tetrahydrofuran and mixed. Under stirring at 200-500 rpm, an aqueous solution containing trifluoromethanesulfonic acid is added dropwise at a rate of 1-5 drops / second. The mixture is then subjected to a co-hydrolysis and polycondensation reaction under reflux conditions. After filtration, the solvent and low-molecular-weight byproducts are removed by vacuum distillation at 60-90℃ for 2-4 hours to obtain a fluorinated polysiloxane intermediate.

[0057] S2, add Karstedt catalyst and raise the temperature to initiate a hydrosilylation reaction; S4, feed the premix obtained in step S3 into a twin-screw extruder for reactive melt extrusion; in step S1, the reaction temperature of the co-hydrolysis polycondensation reaction is 40-60℃, and the reaction time is 4-8 hours; in step S2, the platinum content in the Karstedt catalyst is 10-50 ppm; the reaction temperature of the hydrosilylation reaction is 80-95℃, and the reaction time is 4-6 hours; in step S4, the temperature settings of each zone of the twin-screw extruder are: feeding zone 260-280℃, melt reaction zone 285-315℃, metering zone 290-300℃; the screw speed of the twin-screw extruder is 200-400 rpm;

[0058] This embodiment provides an energy-saving preparation method for polyphenylene sulfide composite materials, evaluating the performance retention rate under low load parameters. The stirring speed is set to 300 rpm, the dropping rate is 2 drops per second, the polycondensation reaction is carried out at 45°C for 5 hours, and the vacuum distillation is carried out at 70°C for 2.5 hours. In the grafting stage, 20 ppm catalyst is used to react at 85°C for 4.5 hours. The material composition is 90 parts by weight of resin with a melt index of 30 g / 10 min and 10 parts by weight of modifier. The extruder melt reaction section is set at 290°C and the rotation speed is 250 rpm. Under these settings, the reactive fluorinated hyperbranched polysiloxane can still self-assemble into nanoscale island structures, eliminating the scattering loss caused by interfacial pores, indicating that this technique has a wide process tolerance.

[0059] Comparative Example 1:

[0060] This comparative example directly uses pure polyphenylene sulfide resin of the same grade, without any modifier treatment, and is directly melt-extruded and injection molded through a twin-screw extruder with the same temperature configuration. Due to the lack of energy absorption mechanism of flexible siloxane phase and low polarizability of trifluoropropyl segment, this material exhibits typical inherent extreme brittleness, and its dielectric constant and dielectric loss show significant signal attenuation characteristics under high frequency testing, which cannot meet the stringent requirements of core components such as millimeter-wave radar domes.

[0061] Comparative Example 2:

[0062] This comparative example uses a traditional physical blending modification scheme to prepare polyphenylene sulfide composite materials. Specifically, by weight, 85 parts of polyphenylene sulfide resin, 10 parts of polyolefin elastomer with a maleic anhydride grafting rate of 1%, 5 parts of polytetrafluoroethylene micro powder, and 0.5 parts of antioxidant are mixed and prepared by the same extrusion process. Due to the introduction of the elastomer, kinetic mismatch occurs, and the heat distortion temperature of the material drops sharply. At the same time, the surface energy difference between polytetrafluoroethylene and the matrix is ​​huge and there is a lack of chemical covalent anchoring, which leads to the formation of micropores at the phase interface. This defect causes severe scattering and a sharp increase in dielectric loss when high-frequency electromagnetic waves penetrate, which inversely proves the non-obviousness of the in-situ construction of microphase separation structure in this invention.

[0063] Furthermore, to demonstrate the necessity of the molar ratio of tetramethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, 4,4-bis(dimethoxymethylsilyl)biphenyl, and methyldimethoxysilane in step S1 as 1:6:2:4, this comparative example also includes a comparative experiment deviating from this core ratio. The molar ratio of the four silanes is adjusted to 1:3:4:4, while the remaining preparation steps are exactly the same as in Example 1. This change aims to compare the specific impact of reducing the fluorinated flexible segments and increasing the rigid biphenyl nodes on the overall performance of the material.

[0064] To demonstrate the necessity of a 0.5 wt% mass fraction of trifluoromethanesulfonic acid in the aqueous solution containing trifluoromethanesulfonic acid in step S1, a concentration comparison example was also set up, with its mass fraction adjusted to 1.0 wt%. The remaining preparation steps were exactly the same as in Example 1. This change aims to compare the effect of excessively high acid concentration on the hydrolytic polycondensation network and final properties. Simultaneously, to demonstrate the necessity of adding allyl glycidyl ether in step S2 at 1.5 times the molar amount of silane-hydrogen bonds, a ratio comparison example was set up, with its addition amount adjusted to 1.0 times. The remaining preparation steps were exactly the same as in Example 1. This change aims to compare the effect of insufficient grafted monomers on interfacial reactions and material toughness.

[0065] Verification experiment:

[0066] To comprehensively evaluate the overall service performance of the materials prepared in the above embodiments and comparative examples, a series of mechanical, thermal, and high-frequency electromagnetic performance verification tests were conducted for practical application scenarios of 5G high-frequency communication and advanced driver assistance systems for new energy vehicles; the aim was to quantify the unexpected synergistic effect of reactive fluorinated hyperbranched polysiloxane modifiers in the matrix.

[0067] Testing standards:

[0068] Notched impact strength testing is performed in accordance with ISO 180 standard established by the International Organization for Standardization; tensile strength is determined according to ISO 527 standard; heat distortion temperature is evaluated according to ISO 75 standard under a load of 1.82 MPa; dielectric constant and dielectric loss are calibrated strictly in accordance with the IPC-TM-650 printed circuit board test method manual under a high frequency environment of 10 GHz.

[0069] Specific testing process:

[0070] The composite materials obtained from extrusion granulation were heat-treated at 150 degrees Celsius to remove residual stress, and then molded into standard test specimens using a precision injection molding machine. Mechanical testing was conducted at room temperature using a universal testing machine and a pendulum impact tester to obtain destructive load data. Thermal testing was performed using a Vicat softening point tester to record the critical deformation temperature. High-frequency dielectric property testing employed a vector network analyzer combined with the resonant cavity method to capture electromagnetic wave transmission and reflection signals of the specimens at a frequency of 10 GHz to accurately invert dielectric parameters. In addition, the specimens were placed in a high-temperature aging chamber at 200 degrees Celsius for 1000 hours, and their impact strength was then retested to evaluate the structural retention rate after thermo-oxidative aging.

[0071] Table 1 Performance test data of Examples 1-5 and Comparative Examples 1-2

[0072] Test Project Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Proportioning Concentration Comparison Proportion to proportion Notched impact strength kJ / m² 18.5 22.1 12.5 20.3 15.8 3.2 12.4 9.8 11.2 10.5 Tensile strength (MPa) 72 68 78 70 75 85 58 65 62 64 Heat distortion temperature (HDT), 1.82 MPa, ℃ 108 106 110 107 109 112 89 104 100 102 Dielectric constant Dk@10GHz 2.56 2.45 2.75 2.50 2.68 3.25 2.85 2.92 2.88 2.80 Dielectric loss Df@10GHz 0.0012 0.0010 0.0014 0.0011 0.0013 0.0035 0.0048 0.0026 0.0022 0.0020 Impact strength retention rate after aging at 200℃ / 1000h 92% 94% 88% 93% 90% 85% 61% 76% 78% 80%

[0073] Experimental data profoundly reveal the technological leap brought about by the molecular-level structural design of this invention; compared with the pure resin Comparative Example 1, the notched impact strength of the series of examples has increased several times, while the dielectric constant and dielectric loss have been significantly suppressed to extremely low levels, and the decrease in heat distortion temperature has been strictly controlled within 5 degrees Celsius; compared with the conventional blending Comparative Example 2, this scheme utilizes the spherical steric hindrance effect and chemical bond confinement of hyperbranched molecules to construct a rigid-flexible nanoscale phase separation structure in situ, eliminating the problems of interfacial porosity and thermal performance collapse caused by physical blending;

[0074] Regarding the verification of the core raw material ratio, data from the ratio comparison ratio of 1:3:4:4 shows that when deviating from the fixed ratio of 1:6:2:4, due to insufficient flexible trifluoropropyl segments and too many rigid biphenyl nodes, the steric hindrance of the hyperbranched polysiloxane is too large and the polarizability cannot be effectively suppressed. Its dielectric loss rebounds to 0.0026, the notched impact strength drops to 9.8 kJ / m², and the aging retention rate decreases significantly. This directly proves the necessity and irreplaceability of the specific molar ratio of 1:6:2:4 in achieving kinetic matching and optimizing the dielectric and mechanical properties of the final composite material.

[0075] Regarding the parameter analysis, the concentration comparison showed that excessively high acid concentrations led to excessively rapid hydrolysis rates, uneven silanol polycondensation, and the formation of more microgels, resulting in a decrease in notched impact strength to 11.2 kJ / m² and an increase in dielectric loss to 0.0022. The proportion comparison with 1.0 times allyl glycidyl ether showed that insufficient grafted monomer content resulted in insufficient density of epoxy groups at the modifier end, failing to form a sufficiently dense covalent anchor with the polyphenylene sulfide matrix. This resulted in poor interfacial bonding at the microphase separation interface, with an impact strength of only 10.5 kJ / m². This fully demonstrates the necessity of adding 0.5 wt% trifluoromethanesulfonic acid and 1.5 times allyl glycidyl ether.

[0076] Furthermore, the specific impact of each process parameter on performance was clarified: Example 2, using the extreme conditions of high shear at 400 rpm and a high-temperature melting zone at 315°C, effectively promoted in-situ nanophase separation in the high-viscosity system, resulting in a notched impact strength of up to 22.1 kJ / m² and a dielectric loss as low as 0.0010. In Example 3, under low shear at 200 rpm and a low-temperature melting zone at 285°C, sufficient relaxation time was given to the rigid and flexible molecular chain segments, increasing the tensile strength to 78 MPa. However, the rate of ring-opening grafting reaction decreased, leading to a drop in impact strength to 12.5 kJ / m² and a slight increase in dielectric loss to 0.0014. The moderate parameters in Examples 4 and 5 achieved a good balance between mechanical and dielectric properties. This indicates that by adjusting specific process parameters such as the extruder temperature and screw speed, the impact strength and dielectric loss of the material can be directionally controlled, fully verifying the robustness of this reactive melt extrusion process under different processing windows and demonstrating its extremely high comprehensive technical advantages in high-frequency transparent components.

[0077] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a polyphenylene sulfide composite material, characterized in that, Includes the following steps: S1, tetramethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, 4,4-bis(dimethoxymethylsilyl)biphenyl and methyldimethoxysilane are added to tetrahydrofuran and mixed. Under stirring at 200-500 rpm, an aqueous solution containing trifluoromethanesulfonic acid is added dropwise at a rate of 1-5 drops / second, and a co-hydrolysis and polycondensation reaction is carried out under reflux conditions. After the reaction is completed, sodium bicarbonate is added in a ratio of 1.1-1.5 times the molar amount of trifluoromethanesulfonic acid to neutralize to neutral. After filtration, the solvent and low molecular weight byproducts are removed by vacuum distillation at 60-90℃ for 2-4 hours to obtain a fluorinated polysiloxane intermediate. S2, the fluorinated polysiloxane intermediate obtained in step S1 is mixed with allyl glycidyl ether, toluene is added, nitrogen gas is introduced for protection, Karstedt catalyst is added and the temperature is raised to carry out hydrosilylation reaction. After the reaction is completed, the solvent and unreacted allyl glycidyl ether are removed by rotary evaporation under reduced pressure to obtain a reactive fluorinated hyperbranched polysiloxane modifier. S3. By weight, take 70-95 parts of polyphenylene sulfide resin and dry it in a vacuum drying equipment. Then, mix the dried polyphenylene sulfide resin with 5-25 parts of reactive fluorinated hyperbranched polysiloxane modifier, 0.05-0.5 parts of grafting accelerator and 0.1-1.0 parts of antioxidant obtained in step S2 in a mixer to obtain a premix. S4. The premix obtained in step S3 is fed into a twin-screw extruder for reactive melt extrusion. The extruded material is cooled in a water tank, air-dried, and pelletized to obtain a polyphenylene sulfide composite material.

2. The method for preparing a polyphenylene sulfide composite material according to claim 1, characterized in that, In step S1, the molar ratio of tetramethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, 4,4-bis(dimethoxymethylsilyl)biphenyl and methyldimethoxysilane is 1:6:2:

4.

3. The method for preparing a polyphenylene sulfide composite material according to claim 1, characterized in that, In step S1, the mass fraction of trifluoromethanesulfonic acid in the aqueous solution containing trifluoromethanesulfonic acid is 0.5 wt%; the reaction temperature of the co-hydrolysis condensation reaction is 40-60℃, and the reaction time is 4-8 hours.

4. The method for preparing a polyphenylene sulfide composite material according to claim 1, characterized in that, In step S2, the amount of allyl glycidyl ether added is 1.5 times the molar amount of silane-hydrogen bonds in the fluorinated polysiloxane intermediate; the platinum content in the Karstedt catalyst is 10~50 ppm; the reaction temperature of the hydrosilylation reaction is 80-95℃, and the reaction time is 4-6 hours.

5. The method for preparing a polyphenylene sulfide composite material according to claim 1, characterized in that, In step S3, the polyphenylene sulfide resin is a linear or cross-linked polyphenylene sulfide with thiol end groups, and its melt index is 20~200g / 10min under the conditions of 315.6℃ and 5kg; the drying temperature of the vacuum drying equipment is 120℃ and the drying time is 4 hours.

6. The method for preparing a polyphenylene sulfide composite material according to claim 1, characterized in that, In step S3, the grafting promoter is selected from quaternary phosphonium salts or imidazole compounds; the antioxidant is a complex of hindered phenolic antioxidants and phosphite antioxidants.

7. The method for preparing a polyphenylene sulfide composite material according to claim 6, characterized in that, The grafting promoter is tetraphenylphosphonium bromide or 2-ethyl-4-methylimidazole.

8. The method for preparing a polyphenylene sulfide composite material according to claim 1, characterized in that, In step S4, the twin-screw extruder is a co-rotating twin-screw extruder, and the temperature settings of each zone are as follows: feeding section 260-280℃, melt reaction section 285-315℃, metering section 290-300℃, and die head 290℃; the screw speed of the twin-screw extruder is 200-400 rpm.