Porous plastic scintillator and 3D printing method thereof

Abstract

The invention discloses a porous plastic scintillator and a 3D printing method thereof.The 3D printing method comprises the steps that S1, raw materials are mixed, the raw materials comprise a main body material, and the main body material comprises polystyrene serving as a matrix, a scintillating substance, a wave shifting agent and a first plasticizer; s2, heating and extruding the mixed main body material through an extrusion molding process to form polystyrene scintillation filaments; and S3, taking the polystyrene scintillation filaments as a printing material, and according to the three-dimensional porous model, printing by adopting a fused deposition molding technology to obtain the porous plastic scintillator. The plastic scintillator raw material is firstly heated and extruded into the filaments, then the filaments are used as the raw material, the porous plastic scintillator is obtained through printing by adopting the fused deposition molding technology, an additional mold is not needed, the preparation process of the plastic scintillator is simplified, and the preparation time is shortened; the porous plastic scintillator is suitable for beta radioactivity detection, is non-toxic and environment-friendly, can be repeatedly used, can be used for on-line monitoring and continuous sample injection, and can be used as a preferred material for replacing scintillation liquid.

Description

Technical Field

[0001] The present invention relates to the technical field of radiation detection equipment, and particularly relates to a porous plastic scintillator and a 3D printing method thereof. Background Art

[0002] At present, liquid scintillation counting is the main analytical technique for measuring β-radionuclides. For environmental radioactivity and nuclear power plant effluents, 3 H, 14 C, 63 Ni, 90 radioactive nuclides such as Sr are usually measured by liquid scintillation counting. Traditional liquid scintillation counting uses an organic solvent as the matrix scintillation solution, which has disadvantages such as poor stability, toxicity, inapplicability to the measurement of high-salt aqueous solutions, and non-reusability.

[0003] Plastic scintillators have been widely used in many aspects such as radiation detection, security inspection, medical and biological research, industrial inspection, and scientific research fields due to their short decay time, high luminous efficiency, good mechanical properties, physical and chemical stability, etc. A plastic scintillator is a solid solution of an organic scintillating substance in a plastic, and its chemical composition and scintillation mechanism are similar to those of a conventional scintillation solution. It usually consists of a matrix, a scintillating substance, and a wavelength shifter, and can be used for the detection of α, β, γ, fast neutrons, protons, cosmic rays, etc. In recent years, the application of plastic scintillators in β-radioactivity measurement has attracted more and more attention. Compared with conventional scintillation solutions, plastic scintillators are non-toxic, chemically stable, can be separated from radioactive solutions after measurement, can be reused, do not produce organic waste liquids, and can be used as alternative materials for conventional liquid scintillation measurement scintillation solutions.

[0004] When a plastic scintillator is used to detect a β-radioactive sample solution, the ray must pass through the solution between the scintillators to reach the surface of the scintillator and excite the solvent molecules. However, the path of β-rays in a substance is short, and the rays are attenuated when passing through the sample solution and no optical signal is generated, thus leading to a new quenching phenomenon, namely particle quenching. Particle quenching is quenching before fluorescence generation, and it mainly occurs in heterogeneous measurements. It is the most important reason for the energy loss of plastic scintillators in β-radionuclide measurement. The lower the ray energy of β-rays, the shorter the range in the medium, and the greater the influence of particle quenching. Therefore, to improve the detection efficiency of β-rays, the plastic scintillator needs to be made into a specific porous shape to ensure that the distance between the sample solution and the scintillator should be as short as possible.

[0005] How to achieve the substitution application of solid plastic scintillators for liquid scintillators is one of the key issues in the field of β nuclide monitoring based on solid plastic scintillators. The common preparation methods of plastic scintillators mainly include bulk thermal polymerization, polymer melt molding and melt extrusion. However, the above preparation methods are not suitable for plastic scintillators used in β radioactive detection. Therefore, there is an urgent need for a manufacturing method for new plastic scintillators to solve the problems existing in the prior art. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a porous plastic scintillator and its 3D printing method.

[0007] The technical solution adopted by the present invention to solve its technical problems is: to provide a 3D printing method for a porous plastic scintillator, comprising the following steps:

[0008] S1. Mix the raw materials, the raw materials including a main material, the main material including polystyrene as a matrix, a scintillating substance, a wavelength shifter and a first plasticizer;

[0009] S2. Heat and extrude the mixed main material through an extrusion molding process to form polystyrene scintillating filaments;

[0010] S3. Use the polystyrene scintillating filaments as printing materials and print a porous plastic scintillator by using a fused deposition modeling technique according to a three-dimensional porous model.

[0011] Preferably, the scintillating substance includes at least one of 2,5-diphenyloxazole, p-terphenyl, 2-(4'-tert-butylphenyl)-5-(4'-biphenyl)-1,3,4-oxadiazole, 2-(4-biphenyl)-5-phenyloxadiazole, 2-(4-biphenyl)-5-(4-tolyl)-1,3,4-oxadiazole.

[0012] Preferably, the wavelength shifter includes at least one of 1,4-bis(5-phenyl-2-oxazolyl)benzene, 1,4-bis(2-methylstyryl)benzene, 1,4-di(4-methylstyryl)benzene, 9,10-diphenylanthracene.

[0013] Preferably, the first plasticizer includes at least one of biphenyl, dioctyl phthalate, ethylbenzene.

[0014] Preferably, in step S1, the mass of the scintillating substance is 0.3 wt% to 4 wt% of the mass of the polystyrene, the mass of the wavelength shifter is 0.001 wt% to 0.1 wt% of the mass of the polystyrene, and the first plasticizer is 1 wt% to 10 wt% of the mass of the polystyrene.

[0015] Preferably, in step S2, the heating and extrusion temperature of the main body material is 180°C to 280°C, and the diameter of the polystyrene scintillating fiber is 1.70 mm to 1.80 mm.

[0016] Preferably, in step S3, printing is performed by a 3D printer. The nozzle diameter of the 3D printer is less than 0.4 mm, the nozzle temperature during printing is 240°C to 260°C, the temperature of the constant temperature chamber of the 3D printer is 60°C to 100°C, the printing speed is less than 40 mm / s, and the printing layer thickness is less than 0.2 mm.

[0017] Preferably, in step S1, the raw materials further include a support material, and the support material includes polyvinyl alcohol and a second plasticizer;

[0018] Step S2 further includes: heating and extruding the mixed support material through an extrusion molding process to form polyvinyl alcohol fibers;

[0019] Step S3 includes: using a dual-nozzle 3D printer for printing. The main nozzle of the 3D printer prints the polystyrene scintillating fibers according to a three-dimensional porous model to form a scintillator with a porous structure, and the auxiliary nozzle of the 3D printer prints and fills the polyvinyl alcohol fibers in the porous structure of the scintillator to form support columns; washing the scintillator with support columns to dissolve the support columns and obtain a porous plastic scintillator.

[0020] Preferably, the mass of the second plasticizer is 10 wt% to 40 wt% of the mass of the polyvinyl alcohol;

[0021] The second plasticizer includes at least one of glycerol, ethylene glycol, sorbitol, and water.

[0022] Preferably, the washing includes: soaking the scintillator with support columns in warm water at 40°C to 60°C for 12 to 48 hours to remove the support columns; or placing the scintillator with support columns in an aqueous solution and removing the support columns by ultrasonic treatment.

[0023] Preferably, in step S2, the heating and extrusion temperature of the support material is 150°C to 190°C, and the diameter of the polyvinyl alcohol fiber is 1.70 mm to 1.80 mm;

[0024] In step S3, during printing, the temperature of the main nozzle is 220°C to 240°C, the hot bed temperature is 100°C to 110°C, the printing speed is 30 mm / s to 60 mm / s, and the printing layer thickness is 0.1 mm to 0.3 mm;

[0025] The temperature of the auxiliary nozzle is 190°C to 220°C, the printing speed is 30 mm / s to 50 mm / s, and the printing layer thickness is 0.1 mm to 0.2 mm.

[0026] The present invention also provides a porous plastic scintillator, which is formed by printing with the 3D printing method of the porous plastic scintillator described in any one of the above; the porous plastic scintillator includes a main body and a plurality of pores that are spaced apart and penetrate through opposite ends of the main body; the pore diameter of the pores is less than 1 mm, and the wall thickness of the pore walls between the pores is less than 1 mm.

[0027] Preferably, the liquid volume of the porous plastic scintillator is greater than 2 mL.

[0028] Advantages of the present invention: First, the plastic scintillator raw material is heated and extruded into filaments, and then the filaments are used as raw materials to print a porous plastic scintillator by using the fused deposition modeling technology, without the need for additional molds, simplifying the preparation process of the plastic scintillator and shortening the preparation time; the porous plastic scintillator is suitable for β radioactive detection, non-toxic, environmentally friendly, reusable, can be used for on-line monitoring of continuous sample introduction, and can be used as the first choice material to replace the scintillation liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0030] Figure 1 is a three-dimensional structural schematic diagram of the 3D printing method of the porous plastic scintillator according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention will now be described in detail with reference to the drawings.

[0032] The 3D printing method of the porous plastic scintillator according to an embodiment of the present invention includes the following steps:

[0033] S1. Mix the raw materials, and the raw materials include a main body material, and the main body material further includes polystyrene as a matrix, a scintillating substance, a wavelength shifter, and a first plasticizer.

[0034] Among them, the scintillating substance includes at least one of 2,5-diphenyloxazole (PPO), p-terphenyl (p-TP), 2-(4'-tert-butylphenyl)-5-(4'-biphenyl)-1,3,4-oxadiazole (b-PBD), 2-(4-biphenyl)-5-phenyloxadiazole (PBD), 2-(4-biphenyl)-5-(4-methylphenyl)-1,3,4-oxadiazole (mPBD). The wavelength shifter includes at least one of 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP), 1,4-bis(2-methylstyryl)benzene (Bis-MSB), 1,4-di(4-methylstyryl)benzene (Me-MSB), 9,10-diphenylanthracene (DPA).

[0035] Considering that pure polystyrene has poor fluidity, to avoid the situation where polystyrene cannot be smoothly extruded from the nozzle or evenly spread on the building platform, and the molecular chain of polystyrene is relatively rigid, and the material is prone to breakage during the 3D printing process, the raw materials in the present invention include a first plasticizer, and the addition of the first plasticizer in the matrix is used to reduce the melt viscosity of polystyrene and improve the interlayer bonding force of polystyrene during 3D printing.

[0036] As an option, the first plasticizer includes at least one of biphenyl, dioctyl phthalate (DOP), and ethylbenzene.

[0037] In the main material, the mass of the scintillating substance is 0.3wt% - 4wt% of the mass of polystyrene, the mass of the wavelength shifter is 0.001wt% - 0.1wt% of the mass of polystyrene, and the first plasticizer is 1wt% - 10wt% of the mass of polystyrene.

[0038] S2. Heat and extrude the mixed main material through an extrusion molding process to form polystyrene scintillating filaments.

[0039] Among them, the heating and extrusion temperature of the main material is 180°C - 280°C.

[0040] In some embodiments, the diameter of the polystyrene scintillating filament is 1.70mm - 1.80mm, preferably 1.75mm.

[0041] S3. Use the polystyrene scintillating filament as the printing raw material, and according to the three-dimensional porous model, adopt the fused deposition modeling technology to print and obtain a porous plastic scintillator.

[0042] Specifically, a three-dimensional porous model of the porous plastic scintillator is pre-constructed; using the fused deposition modeling technology (FDM), with a three-dimensional printer as the printing device, using the polystyrene scintillating filament as the 3D printing raw material, feeding the polystyrene scintillating filament into the nozzle of the three-dimensional printer to be melted; the three-dimensional printer outputs the melted polystyrene scintillating filament according to the set three-dimensional porous model, and layer by layer constructs a porous plastic scintillator with a specific shape and porous structure on the printing platform.

[0043] Among them, the nozzle diameter of the three-dimensional printer is less than 0.4mm, the nozzle temperature during printing is 240°C - 260°C, the constant temperature chamber temperature of the three-dimensional printer is 60°C - 100°C, the printing speed is less than 40mm / s, the printing layer thickness is less than 0.2mm; the positioning accuracy of X and Y is 0.01mm, and Z is 0.0025mm, and the printing accuracy can reach 0.1mm.

[0044] A 3D printing method for a porous plastic scintillator according to another embodiment of the present invention includes the following steps:

[0045] S1. Mix the raw materials, which include a main material and a support material. The main material includes polystyrene as a matrix, a scintillating substance, a wavelength shifter, and a first plasticizer. The support material includes polyvinyl alcohol (PVA) and a second plasticizer.

[0046] In the main material, the scintillating substance includes at least one of 2,5-diphenyloxazole (PPO), p-terphenyl (p-TP), 2-(4'-tert-butylphenyl)-5-(4'-biphenyl)-1,3,4-oxadiazole (b-PBD), 2-(4-biphenyl)-5-phenyloxadiazole (PBD), and 2-(4-biphenyl)-5-(4-methylphenyl)-1,3,4-oxadiazole (mPBD). The wavelength shifter includes at least one of 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP), 1,4-bis(2-methylstyryl)benzene (Bis-MSB), 1,4-bis(4-methylstyryl)benzene (Me-MSB), and 9,10-diphenylanthracene (DPA). The first plasticizer includes at least one of biphenyl, dioctyl phthalate (DOP), and ethylbenzene.

[0047] The mass of the scintillating substance is 0.3 wt% to 4 wt% of the mass of polystyrene, the mass of the wavelength shifter is 0.001 wt% to 0.1 wt% of the mass of polystyrene, and the first plasticizer is 1 wt% to 10 wt% of the mass of polystyrene.

[0048] In the support material, the mass of the second plasticizer is 10 wt% to 40 wt% of the mass of polyvinyl alcohol. The second plasticizer includes at least one of glycerol, ethylene glycol, sorbitol, and water.

[0049] S2. Respectively heat and extrude the main material through an extrusion molding process to form polystyrene scintillating filaments, and heat and extrude the support material to form polyvinyl alcohol filaments.

[0050] The heating and extrusion temperature of the main material is 180°C to 280°C. The diameter of the polystyrene scintillating filaments is 1.70 mm to 1.80 mm, and 1.75 mm can be preferably selected. The heating and extrusion temperature of the support material is 150°C to 190°C, and the diameter of the polyvinyl alcohol filaments is 1.70 mm to 1.80 mm.

[0051] S3. Use the polystyrene scintillating filaments as the printing main raw material and the polyvinyl alcohol filaments as the support raw material, and print a porous plastic scintillator according to a three-dimensional porous model by using a fused deposition modeling technique.

[0052] Specifically, this step S3 further includes:

[0053] S3.1. Pre-build a three-dimensional porous model of the porous plastic scintillator, and use a three-dimensional printer with a dual nozzle as the printing device.

[0054] S3.2. The main nozzle of the 3D printer prints polystyrene scintillating filaments according to the three-dimensional porous model to form a scintillator with a porous structure, and the auxiliary nozzle of the 3D printer prints and fills polyvinyl alcohol filaments in the porous structure of the scintillator to form support columns.

[0055] Among them, the scintillator is formed by layer-by-layer printing and stacking, and the polyvinyl alcohol filaments are also filled layer by layer in the porous structure according to the layer-by-layer printing of the scintillator. For example, after the main nozzle prints the base layer of the scintillator, the bottom layer holes with porous structures are also formed inside. The auxiliary nozzle cooperates to print and fill the polyvinyl alcohol filaments in the bottom layer holes to support in the bottom layer holes; as the printing progresses, when the second layer is printed on the base layer, the second layer holes connected to the bottom layer holes are formed at the same time, and the auxiliary nozzle cooperates to print and fill the polyvinyl alcohol filaments in the second layer holes, and so on until the scintillator with a set height and the support columns filled in its porous structure are completed.

[0056] In the porous structure of the scintillator, the filling density of the support columns formed by polyvinyl alcohol filaments is 10% - 40%.

[0057] Among them, the nozzle diameters of the 3D printer are all less than 0.4 mm. During printing, the temperature of the main nozzle is 220°C - 240°C, the hot bed temperature is 100°C - 110°C, the printing speed is 30 mm / s - 60 mm / s, and the printing layer thickness is 0.1 mm - 0.3 mm; the temperature of the auxiliary nozzle is 190°C - 220°C, the printing speed is 30 mm / s - 50 mm / s, the printing layer thickness is 0.1 mm - 0.2 mm, and the cooling fan is turned on 50% - 100% for cooling during printing.

[0058] S3.3. Wash the scintillator with the support columns to dissolve the support columns and obtain a porous plastic scintillator.

[0059] Among them, the washing includes: soaking the scintillator with the support columns in warm water at 40°C - 60°C for 12 - 48 hours to remove the support columns. Or, place the scintillator with the support columns in an aqueous solution and perform ultrasonic treatment for 1 - 2 hours to remove the support columns.

[0060] The porous plastic scintillator obtained by 3D printing through the above embodiments, as Figure 1 shown, may structurally include a main body 10 and a plurality of pore channels 20 that are spaced apart and penetrate through opposite ends of the main body 10; the pore channels 20 can allow gases or liquids to flow through. The pore diameter (or length / width) of the pore channels 20 is less than 1 mm, and the wall thickness of the pore walls between the pore channels 20 is less than 1 mm. The liquid volume of the porous plastic scintillator is greater than 2 mL, and further greater than 5 mL.

[0061] The main body 10 of the porous plastic scintillator can be a columnar body, a cuboid, a sphere, etc. The columnar body can further be a cylinder, a polygonal column, etc. The pore channels 20 can be at least one of circular, polygonal, and slit-shaped.

[0062] In some embodiments, as Figure 1 shown, the pore channels 20 on the main body 10 are hexagonal; the setting of the hexagonal pore channels makes the pore wall thickness between adjacent pore channels 20 uniform. The cross-section of the porous plastic scintillator is honeycomb-shaped.

[0063] Preferably, to reduce the printing problems caused by complex paths, the shapes and distributions of the pore channels 20 of the porous plastic scintillator are set regularly, which is beneficial to path planning during the printing process.

[0064] The porous plastic scintillator of the present invention is suitable for β-radioactivity detection. When the porous plastic scintillator of the present invention is used for β-radioactivity detection, the porous plastic scintillator is placed in a liquid scintillation vial, and a sample solution is added, and then it can be used for β-radioactivity detection. The porous plastic scintillator has the advantages of non-toxic, environmentally friendly, and reusable, and can be used for on-line monitoring of continuous sample injection.

[0065] The present invention will be further described below through specific embodiments.

[0066] Example 1

[0067] Using polystyrene as the scintillation matrix, 2,5-diphenyloxazole (PPO) is selected as the scintillation substance, 1,4-bis(5-phenyl-2-oxazolyl)benzene is used as the wavelength shifter, and biphenyl is used as the plasticizer.

[0068] Weigh 1000 g of polystyrene powder, 10 g of 2,5-diphenyloxazole, 0.2 g of 1,4-bis(5-phenyl-2-oxazolyl), and 50 g of biphenyl, and mix them evenly as the raw material for extruding plastic filaments.

[0069] Place the raw material of the plastic filaments in an extruder for heating and extrusion. The heating temperature of the extruder is 190 °C, and the diameter of the extrusion hole is 1.75 mm, to obtain scintillation filaments with a uniform diameter of 1.75 mm as the raw material for 3D printing.

[0070] Use 3D modeling software such as SolidWorks to draw the 3D model of the porous plastic scintillator. As Figure 1 shown, it is a porous honeycomb-shaped scintillator column with a diameter of 24 mm and a height of 40 mm. The internal is an equilateral hexagonal hollow pore channel with a pore diameter and side length of 1 mm, and the total number of hollow pore channels is 55.

[0071] Select an FDM printer with a high-temperature constant-temperature chamber. Use the above-mentioned scintillating filaments as the 3D printing raw material, import the 3D model of the above-mentioned porous plastic scintillator, select the printer nozzle diameter to be 0.4 mm, set the nozzle temperature to 250 °C, set the constant-temperature chamber temperature to 60 °C, set the printing speed to 30 mm / s, set the layer thickness to 0.1 mm, and perform printing by layer-by-layer stacking.

[0072] Use a polishing machine to polish the outer surface of the printed plastic scintillator column, and finally obtain a porous honeycomb-shaped scintillator column with a diameter of 24 mm, a height of 40 mm, and an equilateral hexagon-shaped hollow channel with an internal pore diameter and side length of 1 mm.

[0073] Example 2

[0074] Use polystyrene as the scintillation base, select p-terphenyl (p-TP) as the scintillation substance, 1,4-bis(2-methylstyryl)benzene (Bis-MSB) as the wavelength shifter, and biphenyl as the plasticizer.

[0075] Weigh 1000 g of polystyrene powder, 20 g of 2,5-diphenyloxazole, 0.15 g of 1,4-bis(5-phenyl-2-oxazolyl), and 60 g of biphenyl, and mix them evenly as the raw material for extruding plastic filaments.

[0076] Place the raw material of the plastic filament in an extruder for heating and extrusion. The heating temperature of the extruder is 200 °C, and the extrusion hole diameter is 1.8 mm to obtain scintillating filaments with a uniform diameter of 1.8 mm as the 3D printing raw material.

[0077] Use the 3D modeling software SolidWorks to draw the 3D model of the porous plastic scintillator. The porous plastic scintillator is in the shape of a porous cube with a side length of 24 mm, a height of 60 mm, and an equilateral hexagon-shaped hollow channel with an internal pore diameter and side length of 1 mm.

[0078] Select an FDM printer with a high-temperature constant-temperature chamber. Use the above-mentioned scintillating filaments as the 3D printing raw material, import the 3D model of the above-mentioned porous plastic scintillator, select the printer nozzle diameter to be 0.4 mm, set the nozzle temperature to 255 °C, set the constant-temperature chamber temperature to 100 °C, set the printing speed to 10 mm / s, set the layer thickness to 0.1 mm, and perform printing by layer-by-layer stacking.

[0079] Use a polishing machine to polish the outer surface of the printed plastic scintillator column, and finally obtain a porous honeycomb-shaped scintillator column with a diameter of 24 mm, a height of 60 mm, and an equilateral hexagon-shaped hollow channel with an internal pore diameter and side length of 1 mm.

[0080] Taking Example 1 as a representative, verify the background and detection efficiency of the porous honeycomb-shaped scintillator column obtained by printing in Example 1 for β radiation measurement, and use the conventional scintillation solution for β radioactive measurement as Comparative Example 1.

[0081] The porous honeycomb scintillator column of Example 1 was put into a 20 mL polyethylene counting bottle, the bottle cap was tightened, and it was placed in the dark for 1 day. The background of the plastic scintillator was measured on a Quantulus 1220 ultra-low background liquid scintillation spectrometer (PerkinElmer, USA). Then, 0.2 mL of a carbon-14 standard sample solution was evenly dropped on the top of the scintillator column, and ultrasonic oscillation was carried out for 15 min to make the standard solution as evenly dispersed as possible in the scintillator column, forming a test sample for liquid scintillation counting. Subsequently, it was placed on the liquid scintillation spectrometer for measurement, and the detection efficiency of the porous honeycomb scintillator for β-radionuclides was calculated.

[0082] The background sample of the carbon-14 conventional scintillation liquid and the sample added with 0.2 mL of the carbon-14 standard sample solution were also measured on the same liquid scintillation spectrometer, and the measurement results of carbon-14 in Example 1 and Comparative Example 1 were compared. The results are shown in Table 1.

[0083] Table 1

[0084] Scintillator Carbon-14 background Carbon-14 detection efficiency Example 1 2.52 cpm 43.47％ Comparative Example 1 2.49 cpm 60.5％

[0085] As can be seen from the results in Table 1, under the same measurement conditions, the background of the porous plastic scintillator used for β-radioactivity detection is not much different from the background count of the carbon-14 conventional scintillation liquid measurement system. The detection efficiency for carbon-14 is higher than 40%, which fully meets the measurement requirements of sample carbon-14 in environmental monitoring.

[0086] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A 3D printing method for a porous plastic scintillator, characterized in that, It includes the following steps: S1. Mix the raw materials, where the raw materials include a main material, and the main material includes polystyrene as a matrix, a scintillating substance, a wavelength shifter, and a first plasticizer; S2. Heat and extrude the mixed main material through an extrusion molding process to form polystyrene scintillating filaments; S3. Use the polystyrene scintillating filaments as printing materials, and according to a three-dimensional porous model, obtain a porous plastic scintillator by using a fused deposition modeling technique.

2. The 3D printing method of the porous plastic scintillator according to claim 1, characterized in that The scintillating substance includes at least one of 2,5-diphenyloxazole, p-terphenyl, 2-(4'-tert-butylphenyl)-5-(4'-biphenyl)-1,3,4-oxadiazole, 2-(4-biphenyl)-5-phenyloxadiazole, 2-(4-biphenyl)-5-(4-tolyl)-1,3,4-oxadiazole; The wavelength shifter includes at least one of 1,4-bis(5-phenyl-2-oxazolyl)benzene, 1,4-bis(2-methylstyryl)benzene, 1,4-di(4-methylstyryl)benzene, 9,10-diphenylanthracene; The first plasticizer includes at least one of biphenyl, dioctyl phthalate, and ethylbenzene.

3. The 3D printing method of the porous plastic scintillator according to claim 1, characterized in that, In step S1, the mass of the scintillating substance is 0.3 wt% - 4 wt% of the mass of the polystyrene, the mass of the wavelength shifter is 0.001 wt% - 0.1 wt% of the mass of the polystyrene, and the first plasticizer is 1 wt% - 10 wt% of the mass of the polystyrene.

4. The 3D printing method of the porous plastic scintillator according to claim 1, wherein In step S2, the heating and extrusion temperature of the main material is 180°C - 280°C, and the diameter of the polystyrene scintillating filaments is 1.70 mm - 1.80 mm; In step S3, printing is carried out by a three-dimensional printer. The nozzle diameter of the three-dimensional printer is less than 0.4 mm. During printing, the nozzle temperature is 240°C - 260°C, the constant temperature chamber temperature of the three-dimensional printer is 60°C - 100°C, the printing speed is less than 40 mm / s, and the printing layer thickness is less than 0.2 mm.

5. The 3D printing method of the porous plastic scintillator according to any one of claims 1-4, characterized in that, In step S1, the raw materials further include a support material, and the support material includes polyvinyl alcohol and a second plasticizer; Step S2 further includes: heating and extruding the mixed support material through an extrusion molding process to form polyvinyl alcohol filaments; Step S3 includes: using a three-dimensional printer with a dual nozzle to print. The main nozzle of the three-dimensional printer prints the polystyrene scintillating filaments according to the three-dimensional porous model to form a scintillator with a porous structure, and the auxiliary nozzle of the three-dimensional printer prints and fills the polyvinyl alcohol filaments in the porous structure of the scintillator to form support columns; washing the scintillator with support columns with water to dissolve the support columns and obtain a porous plastic scintillator.

6. The 3D printing method of the porous plastic scintillator according to claim 5, characterized in that, The mass of the second plasticizer is 10 wt% - 40 wt% of the mass of the polyvinyl alcohol; The second plasticizer includes at least one of glycerol, ethylene glycol, sorbitol, and water.

7. The 3D printing method of the porous plastic scintillator according to claim 5, characterized in that, The water washing includes: soaking the scintillator with support columns in warm water at 40°C - 60°C for 12 - 48 hours to remove the support columns; or placing the scintillator with support columns in an aqueous solution and removing the support columns by ultrasonic treatment.

8. The 3D printing method of the porous plastic scintillator according to claim 5, characterized in that, In step S2, the heating and extrusion temperature of the support material is 150°C to 190°C, and the diameter of the polyvinyl alcohol fiber is 1.70 mm to 1.80 mm; In step S3, during printing, the temperature of the main nozzle is 220°C to 240°C, the hot bed temperature is 100°C to 110°C, the printing speed is 30 mm / s to 60 mm / s, and the printing layer thickness is 0.1 mm to 0.3 mm; The temperature of the auxiliary nozzle is 190°C to 220°C, the printing speed is 30 mm / s to 50 mm / s, and the printing layer thickness is 0.1 mm to 0.2 mm.

9. A porous plastic scintillator, characterized in that, Formed by 3D printing the porous plastic scintillator according to any one of claims 1-8; The porous plastic scintillator includes a main body and a plurality of pores spaced apart and penetrating opposite ends of the main body; the pore diameter of the pores is less than 1 mm, and the wall thickness of the pore walls between the pores is less than 1 mm.

10. The porous plastic scintillator according to claim 9, wherein, The liquid volume of the porous plastic scintillator is greater than 2 mL.

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