RPS / CaCO3 composite material and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to an RPS / CaCO3 composite material and a preparation method thereof. The RPS / CaCO3 composite material comprises the following raw materials in parts by mass: 100 parts of recycled polystyrene, 1-5 parts of calcium carbonate and 0.25-2.0 parts of a coupling agent, the average particle size of the calcium carbonate is 400-1250 meshes. The recycled polystyrene, the coupling agent and CaCO3 are used as raw materials, and the coupling agent can enable a small amount of calcium carbonate to be well dispersed in an RPS matrix, so that the mechanical property of the composite material is improved, and particularly the tensile and bending properties are improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to an RPS / CaCO3 composite material and its preparation method. Background Technology

[0002] Polystyrene (PS), a widely used plastic material, possesses excellent transparency, insulation, and moldability, and is widely used in packaging, home appliances, automobiles, and other fields. This also generates a large amount of waste polystyrene products. Due to its non-degradable nature, polystyrene persists in the environment for a long time, creating serious ecological problems. Although technologies for recycling polystyrene exist, the actual recycling rate remains low. The main reasons include pollution during the recycling process, degradation of material properties, and increased recycling costs. Therefore, it is necessary to find a suitable method for polystyrene recycling.

[0003] In recent years, research on composite materials has gradually become a hot topic in the field of polymer materials. By combining polystyrene with other materials (such as mineral fillers, fibers, etc.), its physical and mechanical properties can be effectively improved, enhancing the application value of the materials. Simultaneously, the development of composite materials also provides new ideas for the reuse of waste. Calcium carbonate, as a common inorganic filler, has good dispersibility and reinforcing effects, significantly improving the strength and toughness of polymers. Furthermore, calcium carbonate has a relatively low cost, helping to reduce the production cost of composite materials. Therefore, combining recycled polystyrene and calcium carbonate to form new materials presents several challenges: while calcium carbonate can improve the mechanical properties of composite materials, excessive calcium carbonate will reduce their mechanical properties. Additionally, since recycled polystyrene is a waste product, its performance is lower than that of pure polystyrene, making it difficult to uniformly disperse calcium carbonate in the recycled polystyrene matrix, resulting in lower composite material performance. Summary of the Invention

[0004] To address the technical problem in existing recycled polystyrene utilization methods where calcium carbonate is difficult to disperse uniformly in the recycled polystyrene matrix, resulting in low mechanical properties of the composite material, this invention provides an RPS / CaCO3 composite material and its preparation method.

[0005] This invention uses recycled polystyrene (RPS matrix), coupling agent and CaCO3 as raw materials. The coupling agent can effectively disperse a small amount of calcium carbonate in the RPS matrix, thereby improving the mechanical properties of the composite material, especially the tensile and flexural properties.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] An RPS / CaCO3 composite material comprises the following raw materials in parts by weight:

[0008] 100 parts of polystyrene, 1-5 parts of calcium carbonate, and 0.25-2.0 parts of coupling agent were recovered.

[0009] Further specified, the number average molecular weight of the recycled polystyrene is 30,000 to 40,000.

[0010] Furthermore, the recycled polystyrene is obtained by washing, drying, crushing, melting, extruding, and cutting and granulating waste polystyrene products.

[0011] Further specifying, the average particle size of the calcium carbonate is 400 mesh to 1250 mesh.

[0012] Further specifying, the coupling agent is a titanate coupling agent or a silane coupling agent.

[0013] A method for preparing the aforementioned RPS / CaCO3 composite material includes the following steps:

[0014] Step 1: Add the recycled polystyrene, calcium carbonate and coupling agent to a high-speed mixer and stir until evenly mixed;

[0015] Step 2: Add the mixed product to a two-stage screw extruder, and obtain the RPS / CaCO3 composite material through mixing, extrusion, shearing and granulation.

[0016] Further specifying, in step 2, the extrusion temperature is controlled between 175℃ and 185℃.

[0017] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0018] 1. This invention uses recycled polystyrene matrix (RPS matrix), coupling agent and CaCO3 as raw materials to form RPS / CaCO3 composite material. The addition of coupling agent can make a small amount of calcium carbonate well dispersed in RPS matrix, thereby improving the mechanical properties of composite material, especially the tensile and bending properties.

[0019] 2. The material of this invention is a high-performance composite material made by screw extrusion of RPS matrix as the main raw material. It does not damage the inherent mechanical properties of polystyrene, and at the same time realizes the recycling and reuse of waste polystyrene products, which is in line with the concept of green development and is energy-saving and environmentally friendly.

[0020] 3. This invention enables the composite material to maintain excellent mechanical properties with a relatively small amount of CaCO3, which is beneficial for market promotion. The resulting RPS / CaCO3 composite material can be used in billboards, packaging or appliance casings.

[0021] 4. The preparation method of the present invention is simple, requiring only simple screw extrusion blending, without the need to add additional plasticizers, which is not only low in cost, but also easy to industrialize. Attached Figure Description

[0022] Figure 1 Tensile property test diagrams of RPS / CaCO3 composite materials prepared using RPS as raw material and Examples 1-5;

[0023] Figure 2 Graphs showing the flexural properties of RPS / CaCO3 composites prepared using RPS as raw material and in Examples 1-5;

[0024] Figure 3 The tensile properties of the RPS / CaCO3 composite materials prepared in Examples 5-7 are shown in the test diagrams; the particle sizes of calcium carbonate are 400 mesh, 800 mesh, and 1250 mesh.

[0025] Figure 4 The images show the bending stress-strain curves of the RPS / CaCO3 composite materials prepared in Examples 5-7, with calcium carbonate particle sizes of 400 mesh, 800 mesh, and 1250 mesh.

[0026] Figure 5 SEM images of RPS / CaCO3 composites prepared with and without coupling agent. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, but the embodiments of the present invention are not limited thereto. Other methods for preparing the compounds of the present invention, with some conventional modifications to the reaction conditions according to the present invention, are considered to be within the scope of the present invention.

[0028] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0029] It should also be understood that the specific embodiments described above are only used to explain the present invention, and the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0030] This invention discloses an RPS / CaCO3 composite material, comprising the following raw materials in parts by weight:

[0031] 100 parts of polystyrene, 1-5 parts of calcium carbonate, and 0.25-2.0 parts of coupling agent were recovered.

[0032] Preferably, the calcium carbonate is 1 part, 2 parts, 3 parts, 4 parts or 5 parts; the coupling agent is 0.25 parts, 0.5 parts, 1.0 parts, 1.5 parts or 2.0 parts.

[0033] Preferably, the number average molecular weight of the recycled polystyrene is 30,000 to 40,000. For example, the number average molecular weight of the recycled polystyrene is 30,000, 35,000, or 40,000.

[0034] Preferably, recycled polystyrene is produced by washing, drying, crushing, melting, extruding, and cutting and granulating waste polystyrene products.

[0035] Preferably, the average particle size of calcium carbonate is 400 mesh to 1250 mesh. For example, the average particle size of calcium carbonate is 400 mesh, 500 mesh, 600 mesh, 700 mesh, 800 mesh, 900 mesh, 1000 mesh, 1100 mesh or 1250 mesh.

[0036] Preferably, the coupling agent is a titanate coupling agent or a silane coupling agent.

[0037] A method for preparing the aforementioned RPS / CaCO3 composite material includes the following steps:

[0038] Step 1: Add the recycled polystyrene, calcium carbonate and coupling agent to a high-speed mixer and stir until evenly mixed;

[0039] Step 2: Add the mixed product to a two-stage screw extruder, and obtain the RPS / CaCO3 composite material through mixing, extrusion, shearing and granulation.

[0040] In step 2, the extrusion temperature is controlled between 175°C and 185°C. For example, the temperature is controlled at 175°C, 180°C, or 185°C.

[0041] In this invention, RPS / CaCO3 composite material is obtained by extrusion and shear granulation, and then injection molded by an injection molding machine to obtain a sample for performance testing.

[0042] During injection molding, the melt temperature is controlled between 190°C and 210°C. For example, the temperature is controlled at 190°C, 195°C, 200°C, 205°C, or 210°C. During injection molding, the mold temperature is controlled between 90°C and 110°C. For example, the temperature is controlled at 90°C, 95°C, 100°C, 105°C, or 110°C.

[0043] The technical solution of the present invention will be described in detail below with reference to several embodiments.

[0044] It should be noted that, unless otherwise specified, the chemical materials or reagents used in the following embodiments are all commercially available products commonly used in the field.

[0045] It should be noted that, unless otherwise specified, the operations used in the following embodiments are all conventional operations. Unless otherwise specified, the test methods are all existing standard test methods in the art.

[0046] In the following examples, recycled polystyrene is obtained by washing, drying, crushing, melting, extruding, and cutting and granulating waste polystyrene products.

[0047] Waste polystyrene products are generated from packaging, home appliances, automobiles, and other fields. Examples include common waste polystyrene products such as foam packaging bags / boxes, disposable tableware, and appliance packaging boxes. The operating methods and parameters for drying, crushing, melting, and extruding recycled polystyrene are existing technologies and will not be elaborated upon here.

[0048] In this invention, the prepared recycled polystyrene is referred to as RPS matrix (abbreviated as RPS). Dumbbell-shaped and strip-shaped specimens are then prepared using a micro-injection molding machine. The injection melt temperature is 210°C, the mold temperature is 105°C, the injection pressure is 35MPa, and the injection time is 10s.

[0049] According to national standards, the tensile and bending properties of dumbbell-shaped and strip-shaped specimens were tested. The tensile results showed that the tensile strength was 31.87±0.93MPa and the elongation at break was 30.14±3.69%. The three-point bending results showed that the bending modulus was 2097±71MPa and the bending strength was 44.85±0.94MPa.

[0050] Example 1

[0051] In this embodiment, an RPS / CaCO3 composite material comprises the following raw materials in parts by weight:

[0052] 100 parts of polystyrene, 1 part of calcium carbonate, and 0.5 parts of coupling agent were recovered.

[0053] The recycled polystyrene has a number average molecular weight of 40,000; the average particle size of calcium carbonate is 400 mesh. The coupling agent is a silane coupling agent.

[0054] In this embodiment, a method for preparing an RPS / CaCO3 composite material includes the following steps:

[0055] Step 1: First, dry 100 parts of recycled polystyrene and 1 part of calcium carbonate in a vacuum drying oven at 80°C for 12 hours; then add the recycled polystyrene, calcium carbonate and coupling agent to a high-speed mixer and stir until evenly mixed.

[0056] Step 2: Add the mixed product to a two-stage screw extruder, and obtain the RPS / CaCO3 composite material through mixing, extrusion, shearing and granulation; extrusion temperature 180℃.

[0057] The RPS / CaCO3 composite material prepared above was then used to prepare dumbbell-shaped and long strip-shaped specimens using a micro-injection molding machine. The injection melt temperature was 210℃, the mold temperature was 105℃, the injection pressure was 35MPa, and the injection time was 10s.

[0058] According to national standards, the tensile properties were tested, and the results showed that the tensile strength was 34.00±0.54MPa and the elongation at break was 44.54±2.25%.

[0059] According to national standards, the bending performance was tested at three points, and the results showed that the bending modulus was 2185±10MPa and the bending strength was 50.68±2.10MPa.

[0060] Example 2

[0061] In this embodiment, an RPS / CaCO3 composite material comprises the following raw materials in parts by weight:

[0062] 100 parts of polystyrene, 2 parts of calcium carbonate, and 0.5 parts of coupling agent were recovered.

[0063] The recycled polystyrene has a number average molecular weight of 40,000; the average particle size of calcium carbonate is 400 mesh. The coupling agent is a silane coupling agent.

[0064] In this embodiment, the preparation method of an RPS / CaCO3 composite material is described in Example 1.

[0065] The RPS / CaCO3 composite material prepared above was then used to prepare dumbbell-shaped and long strip-shaped specimens using a micro-injection molding machine. The injection melt temperature was 210℃, the mold temperature was 105℃, the injection pressure was 35MPa, and the injection time was 10s.

[0066] According to national standards, the tensile properties were tested, and the results showed that the tensile strength was 34.00±0.89MPa and the elongation at break was 43.12±5.69%.

[0067] According to national standards, the bending performance was tested at three points, and the results showed that the bending modulus was 2218±50MPa and the bending strength was 49.08±0.41MPa.

[0068] Example 3

[0069] In this embodiment, an RPS / CaCO3 composite material comprises the following raw materials in parts by weight:

[0070] 100 parts of polystyrene, 3 parts of calcium carbonate, and 0.5 parts of coupling agent were recovered.

[0071] The recycled polystyrene has a number average molecular weight of 40,000; the average particle size of calcium carbonate is 400 mesh. The coupling agent is a silane coupling agent.

[0072] In this embodiment, the preparation method of an RPS / CaCO3 composite material is described in Example 1.

[0073] The RPS / CaCO3 composite material prepared above was then used to prepare dumbbell-shaped and long strip-shaped specimens using a micro-injection molding machine. The injection melt temperature was 210℃, the mold temperature was 105℃, the injection pressure was 35MPa, and the injection time was 10s.

[0074] According to national standards, the tensile properties were tested, and the results showed that the tensile strength was 33.76±0.76MPa and the elongation at break was 45.32±2.96%.

[0075] According to national standards, the bending performance was tested at three points, and the results showed that the bending modulus was 2200±63MPa and the bending strength was 48.95±1.56MPa.

[0076] Example 4

[0077] In this embodiment, an RPS / CaCO3 composite material comprises the following raw materials in parts by weight:

[0078] 100 parts of polystyrene, 4 parts of calcium carbonate, and 0.5 parts of coupling agent were recovered.

[0079] The recycled polystyrene has a number average molecular weight of 40,000; the average particle size of calcium carbonate is 400 mesh. The coupling agent is a silane coupling agent.

[0080] In this embodiment, the preparation method of an RPS / CaCO3 composite material is described in Example 1.

[0081] The RPS / CaCO3 composite material prepared above was then used to prepare dumbbell-shaped and long strip-shaped specimens using a micro-injection molding machine. The injection melt temperature was 210℃, the mold temperature was 105℃, the injection pressure was 35MPa, and the injection time was 10s.

[0082] According to national standards, the tensile properties were tested, and the results showed that the tensile strength was 34.68±1.28MPa and the elongation at break was 48.51±3.55%.

[0083] According to national standards, the bending performance was tested at three points, and the results showed that the bending modulus was 2226±78MPa and the bending strength was 50.02±0.66MPa.

[0084] Example 5

[0085] In this embodiment, an RPS / CaCO3 composite material comprises the following raw materials in parts by weight:

[0086] 100 parts of polystyrene, 5 parts of calcium carbonate, and 0.5 parts of coupling agent were recovered.

[0087] The recycled polystyrene has a number average molecular weight of 40,000; the average particle size of calcium carbonate is 400 mesh. The coupling agent is a silane coupling agent.

[0088] In this embodiment, the preparation method of an RPS / CaCO3 composite material is described in Example 1.

[0089] The RPS / CaCO3 composite material prepared above was then used to prepare dumbbell-shaped and long strip-shaped specimens using a micro-injection molding machine. The injection melt temperature was 210℃, the mold temperature was 105℃, the injection pressure was 35MPa, and the injection time was 10s.

[0090] According to national standards, the tensile properties were tested, and the results showed that the tensile strength was 33.56±1.17MPa and the elongation at break was 42.99±1.40%.

[0091] According to national standards, the bending performance was tested at three points, and the results showed that the bending modulus was 2289±10MPa and the bending strength was 50.17±0.49MPa.

[0092] Example 6

[0093] In this embodiment, an RPS / CaCO3 composite material comprises the following raw materials in parts by weight:

[0094] 100 parts of polystyrene, 5 parts of calcium carbonate, and 0.5 parts of coupling agent were recovered.

[0095] The recycled polystyrene has a number average molecular weight of 40,000; the average particle size of calcium carbonate is 800 mesh. The coupling agent is a silane coupling agent.

[0096] In this embodiment, the preparation method of an RPS / CaCO3 composite material is described in Example 1.

[0097] The RPS / CaCO3 composite material prepared above was then used to prepare dumbbell-shaped and long strip-shaped specimens using a micro-injection molding machine. The injection melt temperature was 210℃, the mold temperature was 105℃, the injection pressure was 35MPa, and the injection time was 10s.

[0098] According to national standards, the tensile properties were tested, and the results showed that the tensile strength was 33.31±1.45MPa and the elongation at break was 43.90±3.83%.

[0099] According to national standards, the bending performance was tested at three points, and the results showed that the bending modulus was 2256±31MPa and the bending strength was 47.94±0.32MPa.

[0100] Example 7

[0101] In this embodiment, an RPS / CaCO3 composite material comprises the following raw materials in parts by weight:

[0102] 100 parts of polystyrene, 5 parts of calcium carbonate, and 0.5 parts of coupling agent were recovered.

[0103] The recycled polystyrene has a number average molecular weight of 40,000; the average particle size of calcium carbonate is 1250 mesh. The coupling agent is a silane coupling agent.

[0104] In this embodiment, the preparation method of an RPS / CaCO3 composite material is described in Example 1.

[0105] The RPS / CaCO3 composite material prepared above was then used to prepare dumbbell-shaped and long strip-shaped specimens using a micro-injection molding machine. The injection melt temperature was 210℃, the mold temperature was 105℃, the injection pressure was 35MPa, and the injection time was 10s.

[0106] According to national standards, the tensile properties were tested, and the results showed that the tensile strength was 34.18±1.45MPa and the elongation at break was 46.48±2.69%.

[0107] According to national standards, the bending performance was tested at three points, and the results showed that the bending modulus was 2241±49MPa and the bending strength was 47.59±0.61MPa.

[0108] In the tests, the tensile and flexural stresses of recycled polystyrene (RPS) and the RPS / CaCO3 composites prepared in Examples 1–5 were measured. (See attached figures.) Figure 1 and Figure 2 .

[0109] from Figure 1 and Figure 2 It can be seen that using a small amount of calcium carbonate can improve the elongation at break of the composite material. This is because a small amount of calcium carbonate can fill the gaps between the polymers of RPS and improve its tensile properties.

[0110] In the tests, the tensile and flexural stresses of the RPS / CaCO3 composite materials prepared in Examples 5 to 7 are shown in [reference needed]. Figure 3 and Figure 4 .

[0111] See Figure 3 and Figure 4 It can be seen that calcium carbonate with different particle sizes can also increase the elongation at break of RPS.

[0112] Furthermore, the RPS / CaCO3 composite material prepared in Example 5 was used as the test sample for microscopic analysis. At the same time, in order to demonstrate the advantages of the technical solution of the present invention, a control sample was designed: that is, the composite material was prepared according to the method of Example 5, but without the addition of a coupling agent.

[0113] The above test samples and control samples were subjected to SEM testing, and the results are as follows: Figure 5 As shown.

[0114] See Figure 5 The left side shows the test sample with added coupling agent; the right side shows the control sample without added coupling agent. It can be seen that, compared with the control sample, when the coupling agent is added to the test sample, it can not only improve the dispersion uniformity of calcium carbonate, allowing it to be better dispersed in recycled polystyrene, but also make the RPS / CaCO3 composite material prepared by physical extrusion smoother in cross-section; thus improving the tensile and flexural properties of the RPS / CaCO3 composite material.

[0115] Furthermore, referring to the method of Example 5, the amount of coupling agent was changed to 0.25 parts, 1.0 parts, 1.5 parts and 2.0 parts respectively to prepare RPS / CaCO3 composite materials, and their properties were tested, as shown in Table 1.

[0116] Table 1 Effect of Coupling Agent Dosage on Performance

[0117] Tensile strength (MPa) Flexural strength MPa 100RPS / 0.25 coupling agent 31.26±0.66 42.36±0.54 100RPS / 0.5 coupling agent 32.57±0.89 43.92±1.00 100RPS / 1.0 coupling agent 30.43±0.56 41.89±0.41 100RPS / 1.5 coupling agent 28.32±0.41 40.02±0.80 100RPS / 2.0 coupling agent 27.48±0.32 37.80±0.23

[0118] As can be seen from the table above, the mechanical properties of RPS / CaCO3 composite material first increase and then decrease with the increase of coupling agent dosage. When the coupling agent dosage is 0.25-1.0 parts, the tensile strength and flexural strength are relatively good. Preferably, when the coupling agent dosage is 0.5 parts, the tensile strength and flexural strength are the highest, indicating that the mechanical properties of RPS / CaCO3 composite material are the best at this dosage.

[0119] The above are several preferred embodiments of the preparation method of the present invention, but they should not be regarded as limitations on the technical solutions protected by the present invention. Any alternative solutions obtained by those skilled in the art based on the technical ideas of the present invention without creative labor should fall within the protection scope of the present invention.

Claims

1. An RPS / CaCO3 composite material, characterized in that, The following raw materials are included in parts by weight: 100 parts of polystyrene, 1-5 parts of calcium carbonate, and 0.25-2.0 parts of coupling agent were recovered.

2. The RPS / CaCO3 composite material according to claim 1, characterized in that, The number average molecular weight of the recycled polystyrene is 30,000 to 40,000.

3. The RPS / CaCO3 composite material according to claim 1, characterized in that, The recycled polystyrene is obtained by washing, drying, crushing, melting, extruding, and cutting and granulating waste polystyrene products.

4. The RPS / CaCO3 composite material according to claim 1, characterized in that, The average particle size of the calcium carbonate is 400 mesh to 1250 mesh.

5. The RPS / CaCO3 composite material according to claim 1, characterized in that, The coupling agent is a titanate coupling agent or a silane coupling agent.

6. A method for preparing the RPS / CaCO3 composite material according to claim 1, characterized in that, Includes the following steps: Step 1: Add the recycled polystyrene, calcium carbonate and coupling agent to a high-speed mixer and stir until evenly mixed; Step 2: Add the mixed product to a two-stage screw extruder, and obtain the RPS / CaCO3 composite material through mixing, extrusion, shearing and granulation.

7. The preparation method according to claim 6, characterized in that, In step 2, the temperature is controlled between 175°C and 185°C during extrusion.

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