Preparation method of synergistic flame-retardant waste tire rubber powder polystyrene composite material

Abstract

The present application relates to the field of composite material preparation, and more particularly to a synergistic flame-retardant waste tire rubber powder / polystyrene composite material preparation method, which comprises the following steps: S1, preparing polystyrene grafted rubber powder; S2, preparing polystyrene-g-rubber powder / polystyrene composite material; S3, compounding polyphenylene ether, two-dimensional transition metal carbide and phytic acid into a synergistic flame retardant, and adding the same into the polystyrene-g-rubber powder / polystyrene composite material, so as to finally prepare a novel, environment-friendly and halogen-free flame-retardant waste tire rubber powder / polystyrene composite material.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation, and in particular to a method for preparing a polystyrene composite material with synergistic flame retardant waste tire rubber powder. Background Technology

[0002] Polystyrene, as one of the five major general-purpose plastics, has advantages such as good transparency, high rigidity, low moisture absorption, good moldability, excellent electrical insulation, and easy dyeing, and is also inexpensive; it is mainly used in packaging, electronics, automobiles, home appliances, and daily necessities industries. However, general-purpose polystyrene is relatively brittle and has poor impact resistance. To address these issues, we used waste tire rubber powder elastomer to toughen and modify it, and the impact strength of the polystyrene grafted rubber powder / polystyrene composite material was significantly improved (BioResources, 2024, 20(1), 1273-1285). However, the modified rubber powder / polystyrene composite material is a flammable material with an oxygen index of 17-18%, and produces a large amount of smoke when burning. Therefore, how to improve the flame retardant properties of rubber powder / polystyrene composite material is an urgent problem to be solved.

[0003] Although halogenated organic flame retardants (such as octabromodiphenyl ether and tetrabromobisphenol A) have excellent flame-retardant effects on polystyrene, they are banned in the European Union due to environmental concerns. Therefore, there is a growing demand for research into low-toxicity, low-smoke halogen-free flame-retardant polystyrene. For environmentally friendly flame-retardant polystyrene, inorganic flame retardants mainly include inorganic phosphorus and phosphates (red phosphorus, ammonium polyphosphate), layered silicates (montmorillonite), and aluminum hydroxide / magnesium hydroxide systems. However, previous studies have shown that modified magnesium hydroxide or modified aluminum hydroxide can achieve a limiting oxygen index (LOI) of 28% for high-impact polystyrene (HIPS) and a UL94 vertical burning rating of V-0, significantly improving flame retardant performance, but at the cost of a significant decrease in mechanical properties. Furthermore, while magnesium hydroxide / aluminum hydroxide and red phosphorus can synergistically enhance the flame retardant performance of HIPS to nearly 23%, the required amount of flame retardant significantly damages mechanical properties. Polyphenylene ether (PPE) is a flame-retardant, easily charred polymer with excellent heat resistance. It has good compatibility with polystyrene and can be mixed in any proportion with minimal impact on mechanical properties. PPE also possesses a certain degree of flame retardancy; its easy charring characteristic can play a role in retardant flame retardancy during the combustion of polystyrene. However, when used alone as a flame retardant for polystyrene, PPE cannot achieve ideal flame retardant effects. Therefore, PPE is usually compounded with other flame retardants for synergistic flame retardancy. Two-dimensional nanomaterials (graphene, carbon nanotubes, metal double hydroxides, molybdenum disulfide, etc.) prevent heat and mass exchange between the gas and solid phases during combustion through a "zigzag path" barrier effect, thus significantly improving the flame retardant properties of polymers even with small amounts. Therefore, two-dimensional nanomaterials have shown unique advantages in improving the flame retardant properties of polymers. In recent years, two-dimensional transition metal carbides / nitrides (MXenes) have attracted widespread attention in the academic community as a novel type of two-dimensional nanomaterial. MXene possesses a clay-like nanosheet structure, and previous studies have shown that the high barrier effect of the nanoclay sheet structure improves the flame retardant properties of composite materials. Therefore, MXene nanosheets can act as a physical barrier during combustion, thereby enhancing the flame retardant properties of the polymer; simultaneously, the titanium dioxide generated during combustion can catalyze carbon layer formation, suppress smoke, and reduce the release of harmful gases. Thus, MXene shows unique advantages as a synergistic flame retardant in improving the flame retardant and smoke-suppressing properties of polystyrene. Furthermore, phytic acid, as a novel bio-based flame retardant, has attracted widespread attention from international scholars, as its polyphosphate structure exhibits highly efficient flame retardant effects. Therefore, the combination of polyphenylene ether, MXene, and phytic acid is an ideal approach to regulate the synergistic flame retardancy of tire rubber powder / polystyrene composites. Summary of the Invention

[0004] To address the problems existing in the background technology, a method for preparing synergistic flame-retardant waste tire rubber powder polystyrene composite material is proposed. Polyphenylene ether, two-dimensional transition metal carbide and phytic acid are compounded as synergistic flame retardants and added to polystyrene-g-rubber powder / polystyrene composite material to improve the performance of modified rubber powder / polystyrene composite material.

[0005] This invention proposes a method for preparing a synergistic flame-retardant waste tire rubber powder polystyrene composite material, the steps of which are as follows:

[0006] S1. Preparation of polystyrene grafted adhesive powder;

[0007] S2. Preparation of polystyrene-g-adhesive powder / polystyrene composite material;

[0008] S3. Polyphenylene ether, two-dimensional transition metal carbide and phytic acid are compounded as a synergistic flame retardant and added to polystyrene-g-adhesive powder / polystyrene composite material to prepare the finished composite material.

[0009] Preferably, in S1, waste tire rubber powder, benzoyl peroxide, and styrene are used as raw materials to prepare polystyrene grafted rubber powder modified material through bulk polymerization.

[0010] Preferably, in step S1, styrene is washed with 5% sodium hydroxide solution and distilled water to remove the polymerization inhibitor, and then dried with anhydrous sodium sulfate; the adhesive powder is treated sequentially with acetone, 5% sodium hydroxide solution, and 10% hydrochloric acid solution to remove impurities; and benzoyl peroxide is recrystallized.

[0011] Preferably, the preparation method of S1 is as follows: nitrogen gas is introduced into the reaction vessel for 0.5 h, 89% styrene solution containing benzoyl peroxide is added, and the mixture is stirred for 2-3 h before adding the adhesive powder; the reaction temperature is controlled at 85°C by oil bath heating, and the reaction is stopped after 25 h; chloroform is added to the reaction vessel, followed by methanol for precipitation, and finally the grafted product is dried.

[0012] Preferably, the preparation method in S2 is as follows: polystyrene grafted adhesive powder and polystyrene resin are mixed in a ratio of 25:75; the polystyrene and modified adhesive powder are extruded by a single screw extruder, and then cut into appropriate proportions by scissors. The extrusion molding temperature is set between 230-280℃, and the extruded mixture is dried after being cooled with water; it is then processed into granules by a pulverizer and finally dried in a vacuum oven.

[0013] Preferably, the preparation method in S3 is as follows: polyphenylene ether, two-dimensional transition metal carbide and phytic acid are added to polystyrene grafted adhesive powder / polystyrene composite material and processed by single screw extrusion and tableting.

[0014] Preferably, the preparation method in S3 is as follows: 10 wt% phytic acid, 15 wt% two-dimensional transition metal carbide, and 40 wt% polyphenylene ether are added to 25 wt% polystyrene grafted adhesive powder / polystyrene composite material and subjected to single-screw extrusion and sheeting to prepare 10 wt% phytic acid / 15 wt% two-dimensional transition metal carbide / 40% polyphenylene ether / 25 wt% polystyrene grafted adhesive powder / polystyrene composite material.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: It combines polyphenylene ether, two-dimensional transition metal carbides, and phytic acid as a synergistic flame retardant, and adds it to polystyrene-g-rubber powder / polystyrene composite materials to improve the flame retardant performance of the modified rubber powder / polystyrene composite materials, achieving an oxygen index value of 23% or higher, and reducing the peak value of the total heat release and heat release rate of the modified rubber powder / polystyrene composite material to 120 MJ·m⁻¹. -2 and 380Kw·m -2 This allows for the preparation of novel, environmentally friendly, halogen-free flame-retardant waste tire rubber powder / polystyrene composite materials. Detailed Implementation

[0016] Example 1

[0017] Preparation of 25wt% rubber powder / polystyrene composite material: 25wt% rubber powder was simply mixed with polystyrene, and then extruded through a single-screw extruder. The screw extrusion temperature was 180℃, 180℃, and 160℃ in each section. The extruded rubber powder / polystyrene blend was then injection molded. The injection molding temperature was 180℃, 180℃, and 160℃ in each section, thus preparing the rubber powder / polystyrene composite material.

[0018] Example 2

[0019] Preparation of g-polystyrene material from adhesive powder: Styrene was washed with 5% sodium hydroxide solution and distilled water to remove polymerization inhibitors, and then dried with anhydrous sodium sulfate. The adhesive powder was treated sequentially with acetone, 5% sodium hydroxide solution, and 10% hydrochloric acid solution to remove impurities. Benzoyl peroxide (BPO) was recrystallized. Nitrogen gas was bubbled into the reaction vessel for 0.5 h, and a styrene solution (89%) containing dissolved BPO was added. After stirring for 2-3 h, the adhesive powder was added. The reaction was heated in an oil bath at 85°C, and the reaction was stopped after 25 h. Chloroform was added sequentially to the reaction vessel to facilitate pouring, followed by methanol for precipitation. The grafted product was then dried.

[0020] Preparation of 25wt% polystyrene-g-grafted rubber powder / polystyrene composite material: 25wt% polystyrene grafted rubber powder was simply mixed with polystyrene, and then extruded through a single-screw extruder. The screw extrusion temperature was 180℃, 180℃, and 160℃ in each section. The extruded modified rubber powder / polystyrene blend was then injection molded. The injection molding temperature was 180℃, 180℃, and 160℃ in each section, thus preparing the 25wt% polystyrene-g-grafted rubber powder / polystyrene composite material.

[0021] Example 3

[0022] Preparation of 20wt% polyphenylene ether / 25wt% polystyrene-g-adhesive powder / polystyrene composite material: 20wt% polyphenylene ether, 25wt% polystyrene grafted adhesive powder, and polystyrene were simply mixed, and then extruded using a single-screw extruder. The screw extrusion temperatures were 260℃, 260℃, and 220℃ in each section. The extruded modified adhesive powder / polystyrene blend was then injection molded. The injection molding temperatures were 280℃, 280℃, and 200℃ in each section, thus preparing the polyphenylene ether / polystyrene-g-adhesive powder / polystyrene composite material.

[0023] Example 4

[0024] Preparation of 40wt% polyphenylene ether / 25wt% polystyrene-g-adhesive powder / polystyrene composite material: 40wt% polyphenylene ether, 25wt% polystyrene grafted adhesive powder, and polystyrene were simply mixed, and then extruded through a single-screw extruder. The screw extrusion temperatures were 280℃, 280℃, and 230℃ in each section. The extruded modified adhesive powder / polystyrene blend was then injection molded. The injection molding temperatures were 290℃, 290℃, and 230℃ in each section, thus preparing the 40% polyphenylene ether / polystyrene-g-adhesive powder / polystyrene composite material.

[0025] Example 5

[0026] Preparation of 5% MXene / 40% polyphenylene ether / 25% modified adhesive powder / polystyrene composite material: Polystyrene grafted adhesive powder and polystyrene resin were mixed at a ratio of 25 / 75. The polystyrene and modified adhesive powder were co-extruded using a single-screw extruder, and the mixture was cut into appropriate proportions using shears. The extrusion molding temperature was set between 230-280℃. After water cooling, the extruded mixture was dried. It was then processed into granules using a pulverizer and dried in a vacuum oven. 5wt% MXene and 40wt% polyphenylene ether were added to the 25% polystyrene grafted adhesive powder / polystyrene composite material and subjected to single-screw extrusion and sheeting to prepare the 5% MXene / 40% polyphenylene ether / 25% modified adhesive powder / polystyrene composite material.

[0027] Example 6

[0028] Preparation of 15% MXene / 40% polyphenylene ether / 25% modified adhesive powder / polystyrene composite material: Polystyrene grafted adhesive powder and polystyrene resin were mixed at a ratio of 25 / 75. The polystyrene and modified adhesive powder were co-extruded using a single-screw extruder, and the mixture was cut into appropriate proportions using shears. The extrusion molding temperature was set between 230-280℃. After water cooling, the extruded mixture was dried. It was then processed into granules using a pulverizer and dried in a vacuum oven. 15wt% MXene and 40wt% polyphenylene ether were added to the 25% polystyrene grafted adhesive powder / polystyrene composite material and subjected to single-screw extrusion and sheeting to prepare the 15% MXene / 40% polyphenylene ether / 25% modified adhesive powder / polystyrene composite material.

[0029] Example 7

[0030] Preparation of 30% MXene / 40% polyphenylene ether / 25% modified adhesive powder / polystyrene composite material: Polystyrene grafted adhesive powder and polystyrene resin were mixed at a ratio of 25 / 75. The polystyrene and modified adhesive powder were co-extruded using a single-screw extruder, and the mixture was cut into appropriate proportions using shears. The extrusion molding temperature was set between 230-280℃. After water cooling, the extruded mixture was dried. It was then processed into granules using a pulverizer and dried in a vacuum oven. 30wt% MXene and 40wt% polyphenylene ether were added to the 25% polystyrene grafted adhesive powder / polystyrene composite material and subjected to single-screw extrusion and sheeting to prepare the 30% MXene / 40% polyphenylene ether / 25% modified adhesive powder / polystyrene composite material.

[0031] Example 8

[0032] Preparation of a 10% phytic acid / 15% MXene / 40% polyphenylene ether / 25% modified adhesive powder / polystyrene composite material: Polystyrene grafted adhesive powder and polystyrene resin were mixed at a ratio of 25 / 75. The polystyrene and modified adhesive powder were co-extruded using a single-screw extruder, and the mixture was cut into appropriate proportions using shears. The extrusion molding temperature was set between 230-280℃. After water cooling, the extruded mixture was dried. It was then processed into granules using a pulverizer and dried in a vacuum oven. 10wt% phytic acid, 15wt% MXene, and 40wt% polyphenylene ether were added to the 25% polystyrene grafted adhesive powder / polystyrene composite material and subjected to single-screw extrusion and sheeting to prepare the 10% phytic acid / 15% MXene / 40% polyphenylene ether / 25% modified adhesive powder / polystyrene composite material.

[0033] The oxygen index performance of each composite material in Examples 1-8 was tested (Table 1). The results showed that the addition of 40 wt% polyphenylene ether and 15 wt% MXene could increase the oxygen index of the 25 wt% styrene grafted rubber powder / polystyrene composite material to 23%, the addition of 40 wt% polyphenylene ether and 30 wt% MXene could increase the oxygen index of the 25 wt% modified rubber powder / polystyrene composite material to 24.1%, and the addition of 10 wt% phytic acid, 15 wt% MXene and 40 wt% PPO could increase the oxygen index of the 25 wt% modified rubber powder / polystyrene composite material to 24.0%.

[0034] Table 1. Oxygen index properties of each composite material in Examples 1-8

[0035]

[0036] Combustion experiments were conducted using a cone calorimeter (Table 2). The results showed that, compared with the 25wt% modified adhesive powder / polystyrene composite, the total heat release, heat release rate, and mass loss of the 40wt% polyphenylene ether / 15wt% MXene flame retardant / 25wt% modified adhesive powder / polystyrene composite were significantly reduced, consistent with the oxygen index test results above. This demonstrates that, compared with the 25wt% modified adhesive powder / polystyrene composite, the total heat release and heat release rate of the 40wt% polyphenylene ether / 15wt% MXene / 25wt% modified adhesive powder / polystyrene composite decreased from 138.9 MJ·m⁻¹. -2 and 737.47 Kw·m -2 It decreased to 111.08 MJ·m -2 and 367.62 Kw·m -2 Furthermore, the ignition time was delayed from 12 seconds to 53 seconds. These results demonstrate that the flame retardant properties of the 40wt% polyphenylene ether / 15wt% MXene / 25wt% modified adhesive powder / polystyrene composite material are improved.

[0037] Table 2. Characterization of flame retardant properties of MXene / polyphenylene ether / adhesive powder / polystyrene composite materials by cone calorimeter.

[0038]

[0039] The embodiments of the present invention have been described in detail above with reference to the table. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A method for preparing a synergistic flame-retardant waste tire rubber powder polystyrene composite material, characterized in that, The steps are as follows: S1. Preparation of polystyrene grafted adhesive powder; S2. Preparation of polystyrene grafted adhesive powder / polystyrene composite material; S3. Polyphenylene ether, two-dimensional transition metal carbide and phytic acid are compounded into a synergistic flame retardant and added to polystyrene grafted adhesive powder / polystyrene composite material to prepare the finished composite material. The preparation method of S3 is as follows: 10wt% phytic acid, 15wt% two-dimensional transition metal carbide, and 40wt% polyphenylene ether are added to 25wt% polystyrene grafted rubber powder / polystyrene composite material and subjected to single-screw extrusion and sheeting to prepare 10wt% phytic acid / 15wt% two-dimensional transition metal carbide / 40wt% polyphenylene ether / 25wt% polystyrene grafted rubber powder / polystyrene composite material.

2. The method for preparing synergistic flame-retardant waste tire rubber powder polystyrene composite material according to claim 1, characterized in that, S1 uses waste tire rubber powder, benzoyl peroxide, and styrene as raw materials to prepare polystyrene grafted rubber powder modified material through bulk polymerization.

3. The method for preparing synergistic flame-retardant waste tire rubber powder polystyrene composite material according to claim 2, characterized in that, In S1, styrene is washed with 5% sodium hydroxide solution and distilled water to remove the polymerization inhibitor, and then dried with anhydrous sodium sulfate. The adhesive powder is treated sequentially with acetone, 5% sodium hydroxide solution, and 10% hydrochloric acid solution to remove impurities. Benzoyl peroxide is recrystallized.

4. The method for preparing synergistic flame-retardant waste tire rubber powder polystyrene composite material according to claim 2, characterized in that, The preparation method of S1 is as follows: nitrogen gas is introduced into the reaction vessel for 0.5 h, 89% styrene solution containing benzoyl peroxide is added, and the mixture is stirred for 2-3 h before adding the adhesive powder; the reaction temperature is controlled at 85℃ by oil bath heating, and the reaction is stopped after 25 h; chloroform is added to the reaction vessel, followed by methanol for precipitation, and finally the grafted product is dried.

5. The method for preparing synergistic flame-retardant waste tire rubber powder polystyrene composite material according to claim 1, characterized in that, The preparation method of S2 is as follows: polystyrene grafted rubber powder and polystyrene resin are mixed in a ratio of 25:75; polystyrene and polystyrene grafted rubber powder are co-extruded through a single screw extruder, and cut into appropriate proportions by scissors. The extrusion molding temperature is set between 230-280℃. After water cooling, the extruded mixture is dried; it is processed into granules by a pulverizer, and finally dried in a vacuum oven.

6. The method for preparing synergistic flame-retardant waste tire rubber powder polystyrene composite material according to claim 1, characterized in that, The preparation method of S3 is as follows: polyphenylene ether, two-dimensional transition metal carbide and phytic acid are added to polystyrene grafted rubber powder / polystyrene composite material and processed by single screw extrusion and tableting.

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