Graphite-like carbon nitride and preparation method and application thereof

Abstract

The application belongs to the technical field of carbon nitride, and particularly relates to a graphite-like carbon nitride as well as a preparation method and application thereof. The method comprises the following steps: determining the size of the graphite-like carbon nitride to be prepared, selecting a template salt with different sizes according to the size of the graphite-like carbon nitride to be prepared; mixing the template salt with a nitrogen-rich precursor according to the size of the template salt to obtain a reaction precursor; placing the reaction precursor in a reaction furnace for reaction, collecting the product after natural cooling to room temperature after the reaction is completed, mixing the collected product with water for stirring, then filtering, washing and drying, and finally obtaining a graphite-like carbon nitride finished product. The graphite-like carbon nitride prepared by the application has uniform morphology, high crystallinity, high purity and no impurities, and the operation process is simple, fast, relatively low in requirements for production equipment, and high in process fault tolerance, and is not prone to obvious errors due to scale expansion.

Description

Technical Field

[0001] This invention belongs to the field of carbon nitride technology, specifically relating to a graphite-like phase carbon nitride, its preparation method, and its applications. Background Technology

[0002] Graphite-like carbon nitride (i.e., g-C3N4) is composed of C and N elements, forming a π-conjugated system through sp2 hybridization of C and N atoms. It has two basic structural units: a triazine ring (C3N3) and a 3-s-triazine ring (C6N7). These basic structural units extend to form a graphene-like two-dimensional sheet structure, with the sheets bonded together by van der Waals forces. Graphite-like carbon nitride is a typical polymer semiconductor with a band gap of ~2.7 eV, commonly used as a catalyst in photocatalysis. Due to its good thermal and chemical stability, and non-toxicity, it is also frequently used as a polymer filler and flame retardant material. Overall, graphite-like carbon nitride has a wide range of applications.

[0003] Currently, there are three synthesis routes for graphite-like carbon nitride: 1. Chemical vapor deposition (CVD), which involves reacting C and N precursors on the surface of a catalytic substrate to obtain graphite-like carbon nitride. Although this method can produce few-layer graphite-like carbon nitride with high quality, the yield per run is too low, the product is difficult to collect, and it is time-consuming and energy-intensive, making it unsuitable for large-scale applications; 2. Solvothermal method, which generally uses C and N-containing precursors such as melamine and cyanuric chloride as raw materials and hydrazine as a solvent to crystallize and synthesize at a certain temperature. Although the product is uniform, the yield per run is also limited. More importantly, the solvents used have certain toxicity, which is harmful to the environment and the health of production personnel; 3. Solid-state reaction method, which usually uses nitrogen-rich precursors as raw materials to obtain graphite-like carbon nitride through thermal reaction. However, the products obtained by the traditional solid-state reaction method have uneven morphology, mostly being a mixture of bulk and non-uniform flakes, which is not conducive to its further utilization and does not make it easy to give full play to the two-dimensional characteristics of graphite-like carbon nitride.

[0004] Therefore, it is extremely important to provide a method for preparing graphitic carbon nitride that can adjust the morphology of graphitic carbon nitride to obtain a variety of graphitic carbon nitride with different advantages. Summary of the Invention

[0005] The purpose of this invention is to provide a graphite-like phase carbon nitride, its preparation method and application, which can prepare graphite-like phase carbon nitride with uniform products and high morphological consistency, and has the potential for large-scale production.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a method for large-scale preparation of graphite-like phase carbon nitride, comprising the following steps:

[0008] (1) Determine the morphology of the graphitic carbon nitride to be prepared, and select template salts of different sizes according to the morphology of the graphitic carbon nitride to be prepared.

[0009] (2) Depending on the size of the template salt, different methods are used to mix the template salt with the nitrogen-rich precursor to obtain the reaction precursor;

[0010] (3) The reaction precursor is placed in the reactor to react. After the reaction is completed, the product is collected after naturally cooling to room temperature. The collected product is mixed with water and stirred, then filtered, washed and dried to finally obtain graphite phase carbon nitride product.

[0011] In step (1), the morphology of the graphite-like carbon nitride includes spherical or honeycomb-shaped graphite-like carbon nitride, cubic box-shaped graphite-like carbon nitride, and sheet-like graphite-like carbon nitride; the preparation of template salts of different sizes is to prepare freeze-dried salt, precipitated salt, and crystalline salt, wherein the spherical or honeycomb-shaped graphite-like carbon nitride, the cubic box-shaped graphite-like carbon nitride, and the sheet-like graphite-like carbon nitride correspond to freeze-dried salt, precipitated salt, and crystalline salt, respectively.

[0012] Furthermore, the method for preparing the freeze-dried salt is as follows: Template salt and water are mixed at a mass ratio of 1:5 to 20. After mixing, the mixture is continuously stirred until the template salt is fully dissolved to form a clear and transparent liquid. The resulting liquid is frozen at -20 to -60°C until completely solidified, and then vacuum-dried at -20 to 20°C and a pressure of 0 to 100 Pa until completely dry. The freeze-dried salt is collected, wherein the template salt includes sodium chloride.

[0013] Furthermore, the method for preparing the precipitated salt is as follows: prepare a saturated solution of template salt and water, ensuring that the template salt is completely dissolved, add ethanol at a mass ratio of 1:0.5-5, stir until the template salt is fully precipitated, filter, wash with ethanol, and dry by blowing air to obtain the precipitated salt, wherein the template salt includes sodium chloride.

[0014] Furthermore, the method for preparing the crystalline salt is as follows: a template salt with a particle size of 0.3μm to 2mm and a regular geometric shape and a purity of >98% is purchased directly, and the template salt includes sodium chloride.

[0015] Furthermore, in step (2), the specific steps for mixing the template salt and the nitrogen-rich precursor are as follows: the template salt and the nitrogen-rich precursor are mixed by mechanical stirring or grinding at 60 to 1000 rpm for 1 to 10 hours until the template salt and the precursor are fully and uniformly mixed.

[0016] Furthermore, when the template salt is a lyophilized salt, the lyophilized salt and the nitrogen-rich precursor are mixed at a mass ratio of 5 to 150:1; when the template salt is a precipitated salt, the precipitated salt and the nitrogen-rich precursor are mixed at a mass ratio of 20 to 150:1; when the template salt is a crystalline salt, the crystalline salt and the nitrogen-rich precursor are mixed at a mass ratio of 30 to 150:1.

[0017] Furthermore, the nitrogen-rich precursor includes one or more of melamine and dicyandiamide.

[0018] Furthermore, in step (3), the parameters of the reaction process are to raise the temperature to 550°C at a heating rate of 1 to 50°C / min and keep it at that temperature for 0.5 to 5 hours; the mixing and stirring with water is to mix the collected product with 10 times the mass of water and stir at 0 to 1000 rpm for 1 to 10 hours until the soluble substances in the product are fully dissolved and the insoluble substances are fully dispersed.

[0019] The present invention also provides a graphitic carbon nitride prepared by the aforementioned method for preparing graphitic carbon nitride, wherein the graphitic carbon nitride includes spherical or honeycomb graphitic carbon nitride, cubic box-shell graphitic carbon nitride, and sheet-like graphitic carbon nitride.

[0020] The present invention also provides an application of the aforementioned graphite-like carbon nitride in the fields of catalysts, polymer fillers, and flame retardant materials.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention relates to graphitic carbon nitride prepared using a salt template method. The resulting carbon exhibits uniform morphology, high crystallinity, high purity, and is free of impurities, indicating high quality. Furthermore, all morphologies are thin layers, allowing for better utilization of its two-dimensional properties. The prepared graphitic carbon nitride can be controllably sized into three common and typical micromorphologies, further enhancing its adaptability to different application environments. The growth template used is a salt (such as sodium chloride), which is inexpensive, environmentally friendly, and reusable during the preparation process. The graphitic carbon nitride and its preparation method provided by this invention have the potential for large-scale production. The raw materials are readily available and inexpensive, the operation is simple and quick, the requirements for production equipment are relatively low, and the process has high tolerance for error, making it less prone to significant errors due to scale-up. Attached Figure Description

[0023] Figure 1 Scanning micrographs of freeze-dried salt at a 10 μm scale;

[0024] Figure 2 Scanning micrographs of the precipitated salt at a 10 μm scale;

[0025] Figure 3This is a scanning micrograph of crystalline salt under a 100 μm scale.

[0026] Figure 4 Scanning electron micrographs of spherical, graphitic carbon nitride phases on a 10 μm scale;

[0027] Figure 5 Scanning electron micrograph of honeycomb-like graphitic carbon nitride on a 5 μm scale;

[0028] Figure 6 Scanning electron micrographs of cubic box-shaped graphitic carbon nitride phase at a scale of 20 μm;

[0029] Figure 7 Scanning electron micrographs of sheet-like graphitic carbon nitride on a 4 μm scale;

[0030] Figure 8 The X-ray diffraction pattern of carbon nitride, which is a graphite-like phase. Detailed Implementation

[0031] This invention provides a method for preparing graphite-like phase carbon nitride, comprising the following steps:

[0032] I. Preparation of Salt Templates of Different Sizes

[0033] 1. Freeze-dried salt template (hereinafter referred to as freeze-dried salt): The template salt (commonly sodium chloride, but other common salts such as KCl and NH4Cl can also be used, with a purity >98%, the same below) and water are mixed in a mass ratio of 1:5 to 20, preferably 1:9 to 12, and most preferably 1:10. After mixing, the mixture is stirred continuously until the template salt is fully dissolved to form a clear and transparent liquid. The resulting liquid is frozen at -20 to -60°C (preferably -40 to -55°C) until completely solidified, and then vacuum dried at -20 to 20°C (preferably -10 to 10°C) and a pressure of 0 to 100 Pa (preferably 0 to 10 Pa, most preferably 0 to 1 Pa) until completely dry. The freeze-dried salt is collected, and the scanning micrograph of the obtained freeze-dried salt under a 10 μm scale is shown below. Figure 1 As shown.

[0034] 2. Re-precipitation of salt template (hereinafter referred to as precipitated salt): Prepare a saturated solution of template salt and water, ensuring the template salt is completely dissolved. Add ethanol (purity >90%) at a mass ratio of solution to ethanol of 1:0.5–5 (preferably 1:0.9–1.5), stir until the template salt is fully precipitated, filter, wash with ethanol, and dry by forced air drying to obtain the precipitated salt. The scanning micrograph of the obtained precipitated salt under a 10 μm scale is shown below. Figure 2 As shown.

[0035] 3. Crystalline Salt: Purchase directly. Select a high-purity template salt (purity >98%) with a particle size of 0.3μm to 2mm (preferably 10-100μm) and a regular geometric shape. The resulting crystalline salt should be visualized using a scanning micrograph on a 100μm scale, as shown below. Figure 3 As shown.

[0036] Scanned fiber images of different salt templates visually demonstrate that the sizes of salts differ depending on the template.

[0037] II. Mixing

[0038] Select template salts of different sizes and their relative ratios to the nitrogen-rich precursor based on the desired morphology. Common nitrogen-rich compounds such as melamine and dicyandiamide can be used as nitrogen-rich precursors. The specific procedures are as follows:

[0039] 1. Spherical or honeycomb structure: The freeze-dried salt and nitrogen-rich precursor are mixed by mechanical stirring or grinding at 60–1000 rpm, preferably 100–300 rpm, for 1–10 hours, preferably 3–5 hours, until the template salt and precursor are fully and uniformly mixed. The mass ratio of freeze-dried salt to nitrogen-rich precursor is 5–150:1, preferably 7.5–50:1, and most preferably 7.5–15:1.

[0040] When preparing spherical or honeycomb-shaped graphitic carbon nitride, one can also choose to first dissolve the template salt and nitrogen-rich precursor together in water in the above proportion and then undergo a freeze-drying process. The collected product can then be used as the precursor for the next high-temperature reaction.

[0041] 2. Cubic box-shaped: The precipitated salt and nitrogen-rich precursor are mixed by mechanical stirring or grinding at 60–1000 rpm, preferably 100–300 rpm, for 1–10 hours, preferably 3–5 hours, until the template salt and precursor are fully and uniformly mixed. The mass ratio of the precipitated salt to the nitrogen-rich precursor is 20–150:1, preferably 30–80:1, and most preferably 30–50:1.

[0042] 3. Flake Form: The crystalline salt and nitrogen-rich precursor are mixed by mechanical stirring or grinding at 60–1000 rpm, preferably 100–300 rpm, for 1–10 hours, preferably 3–5 hours, until the template salt and precursor are fully and uniformly mixed. The mass ratio of the crystalline salt to the nitrogen-rich precursor is 30–150:1, preferably 30–80:1, and most preferably 40–60:1.

[0043] After mixing, the reaction precursor is obtained.

[0044] III. High-Temperature Reaction

[0045] The mixed reaction precursors are placed in a reactor, and the temperature is increased to 550°C at a heating rate of 1–50°C / min (preferably 5–20°C / min). The temperature is held for 0.5–5 hours (preferably 1–2 hours), and the product is collected after natural cooling to room temperature. The reaction can be carried out in air or under the protection of common inert atmospheres (such as nitrogen, argon, etc.).

[0046] IV. Washing and Collection

[0047] The product from the high-temperature reaction is mixed with 10 times its weight of water and stirred (0–1000 rpm, preferably 100–300 rpm, 1–10 h, preferably 3–5 h) until the soluble components are fully dissolved and the insoluble components are fully dispersed. The mixture is then filtered and washed with water 1–3 times. The product is collected and dried to obtain the final product, graphitic carbon nitride. Alternatively, freeze-drying or other methods can be used for drying without affecting the final quality of the product. The sodium chloride in the mother liquor obtained from the first washing can be recycled.

[0048] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0049] Example 1: A method for preparing spherical, graphite-like carbon nitride, comprising the following steps:

[0050] 1. Preparation of freeze-dried salt template:

[0051] Sodium chloride with a purity >98% and water were mixed at a mass ratio of 1:10. The mixture was stirred continuously until the sodium chloride was fully dissolved to form a clear and transparent liquid. The resulting liquid was frozen at -40°C until completely solidified, and then vacuum dried at -5°C and 0.5 Pa until completely dry, and the freeze-dried salt was collected.

[0052] 2. Mixing:

[0053] The freeze-dried salt and melamine were mixed by mechanical stirring at 300 rpm for 5 hours until they were fully and uniformly mixed to obtain a well-mixed reaction precursor. The freeze-dried salt and melamine were mixed at a mass ratio of 10:1.

[0054] 3. High-temperature reaction:

[0055] The mixed reaction precursors were placed in a reactor and the temperature was increased to 550°C at a heating rate of 10°C / min. The temperature was held for 1.5 hours and then naturally cooled to room temperature before the product was collected.

[0056] 4. Washing and collecting:

[0057] The product obtained in step 3 was mixed with 10 times its mass of water and stirred at 200 rpm for 4 hours until the soluble components were fully dissolved and the insoluble components were fully dispersed. The mixture was then filtered, washed twice with water, collected, and dried to obtain spherical shell-shaped graphitic carbon nitride. Scanning electron micrographs of the spherical shell-shaped graphitic carbon nitride at a 10 μm scale are shown below. Figure 4 As shown.

[0058] Example 2: A method for preparing honeycomb-like graphite-phase carbon nitride, comprising the following steps:

[0059] 1. Preparation of freeze-dried salt template:

[0060] Sodium chloride with a purity >98% and water were mixed at a mass ratio of 1:10. The mixture was stirred continuously until the sodium chloride was fully dissolved to form a clear and transparent liquid. The resulting liquid was frozen at -55°C until completely solidified, and then vacuum dried at -5°C and 0.5 Pa until completely dry, and the freeze-dried salt was collected.

[0061] 2. Mixing:

[0062] The freeze-dried salt and melamine were mixed by mechanical stirring at 100 rpm for 3 hours until they were fully and uniformly mixed to obtain a well-mixed reaction precursor. The freeze-dried salt and melamine were mixed at a mass ratio of 20:1.

[0063] 3. High-temperature reaction:

[0064] The mixed reaction precursors were placed in a reactor and the temperature was increased to 550°C at a heating rate of 10°C / min. The temperature was held for 1.5 hours and then naturally cooled to room temperature before the product was collected.

[0065] 4. Washing and collecting:

[0066] The product obtained in step 3 was mixed with 10 times its mass of water and stirred at 200 rpm for 4 hours until the soluble components were fully dissolved and the insoluble components were fully dispersed. The mixture was then filtered, washed twice with water, collected, and dried to obtain honeycomb-like graphitic carbon nitride. A scanning electron microscope image of the honeycomb-like graphitic carbon nitride at a 5 μm scale is shown below. Figure 5 As shown.

[0067] Example 3: A method for preparing cubic box-shell-like graphite-phase carbon nitride, comprising the following steps:

[0068] 1. Preparation of precipitation salt template:

[0069] Prepare a saturated solution of sodium chloride with a purity >98% and water, ensuring that the sodium chloride is completely dissolved. Add ethanol with a purity >90% at a mass ratio of 1:1, stir until sodium chloride is fully precipitated, filter, wash with ethanol, and dry by blowing air to obtain the precipitated salt.

[0070] 2. Mixing:

[0071] The precipitated salt and melamine were mixed by mechanical stirring at 200 rpm for 5 hours until the precipitated salt and melamine were fully and uniformly mixed to obtain a well-mixed reaction precursor. The freeze-dried salt and melamine were mixed at a mass ratio of 40:1.

[0072] 3. High-temperature reaction:

[0073] The mixed reaction precursors were placed in a reactor and the temperature was increased to 550°C at a heating rate of 10°C / min. The temperature was held for 1.5 hours and then naturally cooled to room temperature before the product was collected.

[0074] 4. Washing and collecting:

[0075] The product obtained in step 3 was mixed with 10 times its mass of water and stirred at 200 rpm for 4 hours until the soluble components were fully dissolved and the insoluble components were fully dispersed. The mixture was then filtered, washed twice with water, collected, and dried to obtain cubic box-shaped graphitic carbon nitride. Scanning electron micrographs of the cubic box-shaped graphitic carbon nitride at a 20 μm scale are shown below. Figure 6 As shown.

[0076] Example 4: A method for preparing sheet-like graphitic carbon nitride, comprising the following steps:

[0077] 1. Obtaining Crystallized Salt

[0078] Choose sodium chloride crystalline salt with a particle size of 0.3μm to 2mm, a regular geometric shape, and a purity of >98% to purchase directly.

[0079] 2. Mixing:

[0080] The crystalline salt and melamine were mixed by mechanical stirring at 200 rpm for 5 hours until the crystalline salt and melamine were fully and uniformly mixed to obtain a well-mixed reaction precursor. The mass ratio of the lyophilized salt to melamine was 50:1.

[0081] 3. High-temperature reaction:

[0082] The mixed reaction precursors were placed in a reactor and the temperature was increased to 550°C at a heating rate of 10°C / min. The temperature was held for 1.5 hours and then naturally cooled to room temperature before the product was collected.

[0083] 4. Washing and collecting:

[0084] The product obtained in step 3 was mixed with 10 times its mass of water and stirred at 200 rpm for 4 hours until the soluble components were fully dissolved and the insoluble components were fully dispersed. The mixture was then filtered, washed twice with water, collected, and dried to obtain flake-like graphitic carbon nitride. Scanning electron micrographs of the flake-like graphitic carbon nitride at a 4 μm scale are shown below. Figure 7 As shown.

[0085] The X-ray diffraction pattern of the obtained graphitic carbon nitride is as follows: Figure 8 As shown.

[0086] By referring to the methods in Examples 1-3 of this application combined with scanning electron microscopy images Figure 4 , Figure 5 , Figure 6 , Figure 7 The different morphologies of the graphitic carbon nitride prepared by this method are clearly visible, confirming the controllable adjustment of morphology by this method. When the template:precursor mass ratio is greater than 10, the honeycomb morphology is dominant, while when it is less than 10, the spherical shell morphology is dominant. At the same time, the morphological consistency of each morphology is also confirmed.

[0087] At the same time, by referring to Figure 8 The X-ray diffraction patterns show that the peaks are sharp, indicating good crystallinity; the peak positions are accurate, indicating accurate phase composition; and the absence of impurity peaks indicates product purity.

[0088] Finally, the aforementioned graphite-like carbon nitride production process has achieved 100-gram-level production, and with equipment upgrades, achieving kilogram-level and ton-level production presents no theoretical challenge. This demonstrates the large-scale production potential of this process.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not 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, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing graphite-like phase carbon nitride, characterized in that, Includes the following steps: (1) Determine the morphology of the graphitic carbon nitride to be prepared, and select template salts of different sizes according to the morphology of the graphitic carbon nitride to be prepared. (2) Depending on the size of the template salt, different methods are used to mix the template salt with the nitrogen-rich precursor to obtain the reaction precursor; (3) The reaction precursor is placed in the reactor to react. After the reaction is completed, the product is collected after naturally cooling to room temperature. The collected product is mixed with water and stirred, then filtered, washed and dried to finally obtain graphite phase carbon nitride product. In step (1), the morphology of the graphite-like carbon nitride includes spherical or honeycomb-shaped graphite-like carbon nitride, cubic box-shaped graphite-like carbon nitride, and sheet-like graphite-like carbon nitride; the preparation of template salts of different sizes is to prepare freeze-dried salt, precipitated salt, and crystalline salt, wherein the spherical or honeycomb-shaped graphite-like carbon nitride, the cubic box-shaped graphite-like carbon nitride, and the sheet-like graphite-like carbon nitride correspond to freeze-dried salt, precipitated salt, and crystalline salt, respectively; The method for preparing the freeze-dried salt is as follows: the template salt and water are mixed in a mass ratio of 1:5 to 20. After mixing, the mixture is stirred until the template salt is fully dissolved to form a clear and transparent liquid. The resulting liquid is frozen at -20 to -60°C until completely solidified, and then vacuum dried at -20 to 20°C and a pressure of 0 to 100 Pa until completely dry. The freeze-dried salt is collected. The template salt includes sodium chloride. The method for preparing the precipitated salt is as follows: prepare a saturated solution of template salt and water, ensuring that the template salt is completely dissolved, add ethanol at a mass ratio of 1:0.5-5, stir until the template salt is fully precipitated, filter, wash with ethanol, and dry by blowing air to obtain the precipitated salt, wherein the template salt includes sodium chloride; The method for preparing the crystalline salt is as follows: a template salt with a particle size of 0.3 μm to 2 mm and a regular geometric shape and a purity of >98% is purchased directly, and the template salt includes sodium chloride; In step (2), the specific steps for mixing the template salt and the nitrogen-rich precursor are as follows: the template salt and the nitrogen-rich precursor are mixed by mechanical stirring or grinding at 60 to 1000 rpm for 1 to 10 hours until the template salt and the precursor are fully and uniformly mixed. When the template salt is a lyophilized salt, the lyophilized salt and the nitrogen-rich precursor are mixed at a mass ratio of 5 to 150:1; when the template salt is a precipitated salt, the precipitated salt and the nitrogen-rich precursor are mixed at a mass ratio of 20 to 150:1; when the template salt is a crystalline salt, the crystalline salt and the nitrogen-rich precursor are mixed at a mass ratio of 30 to 150:

1. The nitrogen-rich precursor includes one or more of melamine and dicyandiamide.

2. The method for preparing graphite-like phase carbon nitride according to claim 1, characterized in that, In step (3), the parameters of the reaction process are to raise the temperature to 550°C at a heating rate of 1 to 50°C / min and keep it at that temperature for 0.5 to 5 hours; the mixing and stirring with water is to mix the collected product with 10 times the mass of water and stir at 0 to 1000 rpm for 1 to 10 hours until the soluble substances in the product are fully dissolved and the insoluble substances are fully dispersed.

3. A graphitic carbon nitride prepared by the method for preparing graphitic carbon nitride as described in any one of claims 1-2, characterized in that, The graphite-like carbon nitride includes spherical or honeycomb-shaped graphite-like carbon nitride, cubic box-shell-shaped graphite-like carbon nitride, and sheet-like graphite-like carbon nitride.

4. An application of the graphite-like carbon nitride as described in claim 3 in the fields of catalysts, polymer fillers and flame retardant materials.

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