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

Abstract

The invention relates to the field of composite material preparation, in particular to a preparation method of a synergistic flame-retardant waste tire rubber powder polystyrene composite material, which comprises the following steps: S1, preparing polystyrene grafted rubber powder; s2, preparing a polystyrene-g-rubber powder / polystyrene composite material; s3, polyphenyl ether, two-dimensional transition metal carbide and phytic acid are compounded into a synergistic flame retardant, the synergistic flame retardant is added into the polystyrene-g-rubber powder / polystyrene composite material, and finally the novel, environment-friendly, halogen-free and flame-retardant waste tire rubber powder / polystyrene composite material is prepared.

Description

Technical Field

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

[0002] As one of the five general-purpose plastics, polystyrene has the advantages of good transparency, high rigidity, low hygroscopicity, good formability, excellent electrical insulation, easy dyeing, and low price. It is mainly used in packaging, electronics, automobiles, home appliances, and daily necessities. However, general-purpose polystyrene is brittle and has poor impact resistance. To address the above problems, we used waste tire rubber powder elastomer to toughen and modify it, and the impact strength of polystyrene grafted rubber powder / polystyrene composites was significantly improved (BioResources, 2024, 20(1), 1273-1285). However, the modified rubber powder / polystyrene composite is a combustible material with an oxygen index value of 17-18%, and it produces a large amount of smoke when burned. Therefore, how to improve the flame retardant properties of rubber powder / polystyrene composites is a problem that needs to be solved urgently.

[0003] Although halogen-containing organic additive flame retardants (octabromobiphenyl ether, tetrabromobisphenol A, etc.) have a good flame retardant effect on polystyrene, they are banned by the European Union due to the environmental problems of the flame retardants themselves. Therefore, the research on the development of low-toxic and low-smoke halogen-free flame retardant polystyrene is getting louder and louder. For environmentally friendly flame retardant polystyrene, inorganic additive flame retardants mainly include inorganic phosphorus and phosphates (red phosphorus, ammonium polyphosphate), layered silicates (montmorillonite), aluminum hydroxide / magnesium hydroxide system, etc. However, previous studies have shown that the flame retardant limit oxygen index of modified magnesium hydroxide or modified aluminum hydroxide for high-impact polystyrene (HIPS) reaches 28%, and the UL94 vertical combustion reaches V-0 level, and the flame retardant properties are significantly improved, but the mechanical properties are greatly reduced. In addition, the synergistic flame retardant limit oxygen index of magnesium hydroxide / aluminum hydroxide and red phosphorus for HIPS is close to 23%, but the amount of flame retardant added is relatively large, which has a greater damage to the mechanical properties. Polyphenylene ether is a polymer that is flame-retardant, easy to form carbon, and has excellent heat resistance. It has good compatibility with polystyrene and can be mixed in any proportion without much effect on the mechanical properties. At the same time, polyphenylene ether has a certain degree of flame retardancy, and its easy carbonization property can play a flame retardant role in the combustion process of polystyrene. However, when polyphenylene ether is used alone as a flame retardant for polystyrene, it cannot achieve the ideal flame retardant effect. Therefore, polyphenylene ether is usually compounded with other flame retardants for synergistic flame retardancy. Two-dimensional nanomaterials (graphene, carbon nanotubes, metal double hydroxides, molybdenum disulfide, etc.) prevent the heat and mass exchange between the gas phase and the solid phase during the combustion process through the "tortuous path" barrier effect, so adding a small amount can significantly improve the flame retardant properties of polymers. Therefore, two-dimensional nanomaterials have shown unique advantages in improving the flame retardant properties of polymers. In recent years, two-dimensional transition metal carbon / nitride (MXene) as a new type of two-dimensional nanomaterial has attracted widespread attention in the academic community. MXene has characteristics such as a clay-like nanosheet structure. 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 the combustion process, thereby improving the flame retardant properties of polymers; at the same time, the titanium dioxide generated during the combustion process can catalyze the formation of carbon layers, suppress smoke, and reduce the release of harmful gases. Therefore, MXene has shown unique advantages as a synergistic flame retardant to improve the flame retardant and smoke suppression properties of polystyrene. In addition, phytic acid has attracted widespread attention from foreign scholars as a new type of bio-based flame retardant, and its polyphosphoric acid structure has a highly efficient flame retardant effect. Therefore, the compounding of polyphenylene ether, MXene and phytic acid is an ideal way to regulate the synergistic flame retardancy of tire rubber powder / polystyrene composites. Summary of the invention

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

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

[0006] S1, preparing polystyrene grafted rubber powder;

[0007] S2, preparing a polystyrene-g-rubber powder / polystyrene composite material;

[0008] S3. Compounding polyphenylene ether, two-dimensional transition metal carbide and phytic acid into a synergistic flame retardant, adding the mixture into a polystyrene-g-rubber powder / polystyrene composite material, and preparing a finished composite material.

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

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

[0011] Preferably, the preparation method in S1 is as follows: nitrogen is introduced into the reaction container for 0.5 h, 89% styrene solution containing benzoyl peroxide is added, and the rubber powder is added after stirring for 2-3 h; the reaction temperature is controlled to 85° C. by heating in an oil bath, and the reaction is terminated after 25 h; chloroform is added to the reaction container, followed by methanol for precipitation, and finally the grafted product is dried.

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

[0013] Preferably, the preparation method in S3 is as follows: adding polyphenylene ether, two-dimensional transition metal carbide and phytic acid into a polystyrene grafted rubber powder / polystyrene composite material for single-screw extrusion and tableting.

[0014] Preferably, the preparation method in 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 for single-screw extrusion and tableting to prepare 10wt% phytic acid / 15wt% two-dimensional transition metal carbide / 40% polyphenylene ether / 25wt% polystyrene grafted rubber powder / polystyrene composite material.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: polyphenylene ether, two-dimensional transition metal carbide and phytic acid are compounded into a synergistic flame retardant, which is added to a polystyrene-g-rubber powder / polystyrene composite material to improve the flame retardant performance of the modified rubber powder / polystyrene composite material, so that its oxygen index value reaches 23% or more, and the total heat release amount and the peak value of the heat release rate of the modified rubber powder / polystyrene composite material during combustion are reduced to 120MJ·m -2 and 380Kw·m -2 , thereby preparing a new, environmentally friendly, halogen-free flame-retardant waste tire rubber powder / polystyrene composite material. DETAILED DESCRIPTION

[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, with the temperatures of the screw extrusion sections being 180°C, 180°C and 160°C, and single screw extrusion was performed. The extruded rubber powder / polystyrene blend was injection molded, with the temperatures of the injection molding sections being 180°C, 180°C and 160°C, to prepare a rubber powder / polystyrene composite material.

[0018] Example 2

[0019] Preparation of rubber powder-g-polystyrene material: 5% sodium hydroxide solution and distilled water were used to wash the styrene to remove the inhibitor, and then dried with anhydrous sodium sulfate. The rubber powder was treated with acetone, 5% sodium hydroxide solution, and 10% hydrochloric acid solution in turn to remove impurities in the rubber powder. Benzoyl peroxide (BPO) was recrystallized. Nitrogen was introduced into the reaction vessel for 0.5h, and a styrene solution (89%) containing BPO was added. After stirring for 2-3h, the rubber powder was added, and the reaction temperature was controlled to 85°C by heating in an oil bath. The reaction was terminated after 25h. Chloroform was added to the reaction vessel in turn to make it easy to pour out, and then methanol was added for precipitation, and the grafted product was dried.

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

[0021] Example 3

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

[0023] Example 4

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

[0025] Example 5

[0026] Preparation of 5% MXene / 40% polyphenylene ether / 25% modified rubber powder / polystyrene composite material: Mix polystyrene grafted rubber powder and polystyrene resin in a ratio of 25 / 75. Polystyrene and modified rubber powder are blended and extruded through a single screw extruder, and they are cut into appropriate proportions with scissors. The extrusion molding temperature is set between 230-280°C, and the extruded mixture is water-cooled and then dried. It is processed into particles by a pulverizer and dried in a vacuum oven. 5wt% MXene and 40wt% polyphenylene ether are added to 25% polystyrene grafted rubber powder / polystyrene composite materials for single screw extrusion and tableting to prepare 5% MXene / 40% polyphenylene ether / 25% modified rubber powder / polystyrene composite materials.

[0027] Example 6

[0028] Preparation of 15% MXene / 40% polyphenylene ether / 25% modified rubber powder / polystyrene composite material: Mix polystyrene grafted rubber powder and polystyrene resin in a ratio of 25 / 75. Polystyrene and modified rubber powder are blended and extruded through a single screw extruder, and cut into appropriate proportions with scissors. The extrusion molding temperature is set between 230-280°C, and the extruded mixture is water-cooled and then dried. It is processed into particles by a pulverizer and dried in a vacuum oven. 15wt% MXene and 40wt% polyphenylene ether are added to 25% polystyrene grafted rubber powder / polystyrene composite material for single screw extrusion and tableting to prepare 15% MXene / 40% polyphenylene ether / 25% modified rubber powder / polystyrene composite material.

[0029] Example 7

[0030] Preparation of 30% MXene / 40% polyphenylene ether / 25% modified rubber powder / polystyrene composite material: Mix polystyrene grafted rubber powder and polystyrene resin in a ratio of 25 / 75. Polystyrene and modified rubber powder are blended and extruded through a single screw extruder, and they are cut into appropriate proportions with scissors. The extrusion molding temperature is set between 230-280°C, and the extruded mixture is water-cooled and then dried. It is processed into particles by a pulverizer and dried in a vacuum oven. 30wt% MXene and 40wt% polyphenylene ether are added to 25% polystyrene grafted rubber powder / polystyrene composite materials for single screw extrusion and tableting to prepare 30% MXene / 40% polyphenylene ether / 25% modified rubber powder / polystyrene composite materials.

[0031] Example 8

[0032] Preparation of 10% phytic acid / 15% MXene / 40% polyphenylene ether / 25% modified rubber powder / polystyrene composite material: polystyrene grafted rubber powder and polystyrene resin are mixed in a ratio of 25 / 75. Polystyrene and modified rubber powder are blended and extruded through a single screw extruder, and they are cut into appropriate proportions by scissors. The extrusion molding temperature is set between 230-280°C, and the extruded mixture is water-cooled and then dried. It is processed into particles by a pulverizer and dried in a vacuum oven. 10wt% phytic acid, 15wt% MXene, and 40wt% polyphenylene ether are added to 25% polystyrene grafted rubber powder / polystyrene composite materials for single screw extrusion and tableting to prepare 10% phytic acid / 15% MXene / 40% polyphenylene ether / 25% modified rubber powder / polystyrene composite materials.

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

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

[0035]

[0036] The combustion test was carried out by cone calorimeter (Table 2). The results showed that compared with the 25wt% modified rubber powder / polystyrene composite material, the total heat release, heat release rate and mass loss of the 40wt% polyphenylene ether / 15wt% MXene flame retardant / 25wt% modified rubber powder / polystyrene composite material were significantly reduced, which was consistent with the above oxygen index test results, proving that compared with the 25wt% modified rubber powder / polystyrene composite material, the total heat release and heat release rate of the 40wt% polyphenylene ether / 15wt% MXene / 25wt% modified rubber powder / polystyrene composite material were 138.9MJ·m -2 and 737.47Kw·m -2 Down to 111.08 MJ·m -2 and 367.62Kw·m -2 In addition, the ignition time was delayed from 12s to 53s. The above results prove that the flame retardant properties of 40wt% polyphenylene ether / 15wt% MXene / 25wt% modified rubber powder / polystyrene composites are improved.

[0037] Table 2. Cone calorimeter characterization of flame retardancy of MXene / polyphenylene ether / rubber powder / polystyrene composites

[0038]

[0039] The above describes the implementation modes of the present invention in detail in conjunction with the table, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A method for preparing a synergistic flame retardant waste tire rubber powder polystyrene composite material, characterized in that: Here are the steps: S1, preparing polystyrene grafted rubber powder; S2, preparing a polystyrene-g-rubber powder / polystyrene composite material; S3. Compounding polyphenylene ether, two-dimensional transition metal carbide and phytic acid into a synergistic flame retardant, adding the mixture into a polystyrene-g-rubber powder / polystyrene composite material, and preparing a finished composite material.

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

3. The method for preparing the 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 therein, and then dried with anhydrous sodium sulfate; the rubber powder is treated with acetone, 5% sodium hydroxide solution, and 10% hydrochloric acid solution in sequence to remove impurities in the rubber powder; and benzoyl peroxide is recrystallized.

4. The method for preparing the synergistic flame retardant waste tire rubber powder polystyrene composite material according to claim 2, characterized in that: The preparation method in S1 is as follows: nitrogen is introduced into the reaction container for 0.5 h, 89% styrene solution containing benzoyl peroxide is added, and the rubber powder is added after stirring for 2-3 h; the reaction temperature is controlled to 85°C by heating in an oil bath, and the reaction is terminated after 25 h; chloroform is added to the reaction container, followed by methanol for precipitation, and finally the grafted product is dried.

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

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

7. The method for preparing the synergistic flame retardant waste tire rubber powder polystyrene composite material according to claim 6, characterized in that: The preparation method in 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 for single-screw extrusion and tableting to prepare 10wt% phytic acid / 15wt% two-dimensional transition metal carbide / 40% polyphenylene ether / 25wt% polystyrene grafted rubber powder / polystyrene composite material.

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