A method for preparing a 3D printed plastic scintillator

Abstract

The invention discloses a method for preparing a 3D printed plastic scintillator. The method comprises the following steps: dissolving 2,5-diphenyloxazole and 1,4-bis(5-phenyl-2-oxazolyl)benzene in a styrene-maleic anhydride copolymer in a certain proportion, mixing them uniformly, and obtaining a liquid A; then heating the liquid A to polymerize the liquid A to form a solid material A, and then adding the solid material A into a twin-screw extruder, melt-extruding and granulating the solid material A, and then using the obtained material A particles to perform 3D printing to form a material A cavity tube having a left-right through cavity; then dissolving ZnO nanoparticles, 2,5-diphenyloxazole and 1,4-bis(5-phenyl-2-oxazolyl)benzene in a certain proportion in the styrene-maleic anhydride copolymer, mixing them uniformly, and obtaining a liquid B; finally, prepolymerizing the liquid B, injecting the prepolymer into a closed container, injecting nitrogen to exhaust the air, and then slowly injecting the liquid B prepolymer into the material A cavity tube, and then heating the prepolymer to polymerize the solid material A to obtain a 3D printed plastic scintillator, thereby improving the light yield of the scintillator and the conduction efficiency of photons.

Description

Technical Field

[0001] The invention relates to a method for preparing a 3D printing plastic scintillator. Background Art

[0002] Scintillator is a type of material that can emit light after absorbing high-energy particles or rays. It, together with light collecting components and photoelectric conversion devices, constitutes a radiation detector that is used to detect various high-energy particles and rays. It is widely used in high-energy physics, nuclear physics, radiation medicine, geological exploration, explosion-proof detection and other fields.

[0003] Scintillators used in radiation detectors can be divided into two categories: organic scintillators and inorganic scintillators. Plastic scintillators are solid solutions of organic scintillators in plastics. They belong to organic scintillators and can be used to detect α, β, γ, fast neutrons, protons, cosmic rays and fission fragments. The components of plastic scintillators are usually composed of matrix scintillators and wave shifters. When irradiated by high-energy rays and high-energy particles, they can emit fluorescence of a specific wavelength. They have the advantages of non-deliquescent, stable performance, radiation resistance, short scintillation decay time and low price. They are a widely used scintillator today.

[0004] However, due to the material of plastic scintillators, the current light yield of plastic scintillators is relatively low. Because the atomic number of plastic scintillators is small and their ability to absorb radiation is weak, a large number of high-energy particles that pass through the scintillator have not yet stimulated the scintillator in the scintillator to emit light, and the detector has requirements for the decay count rate of the detected rays, which is manifested in the use of the detector as a requirement for the amount of photons generated. Therefore, in order to capture enough rays and achieve the ideal detection effect, the size of the scintillator is often designed to be very large. Taking a certain gamma-ray method for coal gangue identification equipment for coal mine conditions as an example, the size of the scintillator it uses is 1m*0.2m*0.1m and weighs tens of kilograms, which creates obstacles for detection and use in narrow spaces such as mines, and hinders the application of technologies such as natural ray method coal gangue identification in coal mines and other fields.

[0005] In addition, the photons generated by the current plastic scintillator need to be transmitted to the photomultiplier tube through optical glass or optical fiber for detection. The collection and transmission path of photons is: scintillator-light-guiding glass-photomultiplier tube. This three-level collection mechanism has two interfaces: scintillator to light-guiding glass, and light-guiding glass to photomultiplier tube. Photons suffer from refraction and absorption losses when crossing the interface. Due to the problem of the preparation process, there is inevitably a gap between the two interfaces, resulting in low coupling efficiency of the photon transmission path, affecting the detection accuracy. Although there are literature reports that the contact area between the optical fiber and the scintillator can be increased by mechanically grooving the plastic scintillator to place the transmission optical fiber, thereby improving the coupling efficiency of the light transmission path, this process also has the problem of scratching the contact surface between the plastic scintillator and the optical fiber, and the improvement of light transmission efficiency is not obvious.

[0006] In addition, the current plastic scintillator preparation process still mainly adopts the process of solidifying liquid materials through molds. When faced with small-batch production and special-shaped scintillators, there are problems such as cumbersome mold preparation process and high cost.

[0007] Therefore, how to increase the light yield of plastic scintillators, improve the photon transmission efficiency, and adapt to the preparation of scintillators with special shapes are still urgent problems to be solved. Summary of the invention

[0008] In view of the above-mentioned problems of low light yield and low photon conduction efficiency of current plastic scintillators, the present invention provides a method for preparing a 3D printed plastic scintillator, wherein the plastic substrate, the luminescent material 2,5-diphenyloxazole (PPO) and the wave shifter 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP) are divided into two parts, one of which is printed into a cavity tube material with a left and right through cavity by 3D printing technology, and the other part is added with high atomic number material ZnO nanoparticles as ray capture material and auxiliary scintillator to increase light yield. The specific technical scheme is as follows:

[0009] A method for preparing a 3D printed plastic scintillator comprises the following steps:

[0010] 1) Dissolve 2,5-diphenyloxazole and 1,4-bis(5-phenyl-2-oxazolyl)benzene in a certain proportion in styrene-maleic anhydride copolymer, mix well, and obtain liquid A;

[0011] 2) The liquid A is heated and polymerized to form a solid material A, and then the solid material A is added to a twin-screw extruder, melt-extruded and granulated, and then the obtained material A particles are used for 3D printing to form a material A cavity tube with a left and right through cavity;

[0012] 3) Dissolve ZnO nanoparticles, 2,5-diphenyloxazole and 1,4-bis(5-phenyl-2-oxazolyl)benzene in a certain proportion in styrene-maleic anhydride copolymer, mix well, and obtain liquid B;

[0013] 4) After prepolymerizing liquid B, inject it into a sealed container, inject nitrogen to expel the air, then slowly inject the liquid B prepolymer into the cavity tube of material A, and then heat and polymerize to obtain a new type of 3D printed plastic scintillator.

[0014] In the aforementioned method for preparing a 3D printed plastic scintillator, in step 1), in the liquid A, the mass fraction concentration of 2,5-diphenyloxazole (PPO) is 0.6-1.2%, and the mass fraction concentration of 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP) is 0.01-0.03%.

[0015] Preferably, in the liquid A, the mass fraction concentration of 2,5-diphenyloxazole (PPO) is 1%, and the mass fraction concentration of 1,4-bis(5-phenyl-2-oxazolyl)benzene is 0.02%.

[0016] In the aforementioned 3D printed plastic scintillator preparation method, in step 2), the temperature at which the liquid A is heated and polymerized to form the solid material A is 140-150°C, and the polymerization time is 48 hours; the parameters of the melt extrusion granulation are a melt flow rate (190°C, based on 2.16 kg) of 1.25 g / 10 min.

[0017] In the aforementioned 3D printed plastic scintillator preparation method, in step 2), the end face cavity diameter size of the obtained A material cavity tube is 0.01m.

[0018] In the aforementioned 3D printed plastic scintillator preparation method, in step 3), in the B liquid, the mass fraction concentration of ZnO nanoparticles is 8-12%, the mass fraction concentration of 2,5-diphenyloxazole (PPO) is 0.6-1.2%, and the mass fraction concentration of 1,4-bis(5-phenyl-2-oxazolyl)benzene is 0.01-0.03%.

[0019] Preferably, in the liquid B, the mass fraction concentration of ZnO nanoparticles is 10%, the mass fraction concentration of 2,5-diphenyloxazole (PPO) is 1%, and the mass fraction concentration of 1,4-bis(5-phenyl-2-oxazolyl)benzene is 0.02%.

[0020] In the aforementioned method for preparing 3D printed plastic scintillators, in step 4), the liquid B is pre-polymerized and heated to 55°C, and the temperature is maintained for 36 hours; then the temperature is raised to 95°C at a rate of 5°C / h and maintained for 120 hours.

[0021] In the aforementioned method for preparing a 3D printed plastic scintillator, in step 4), the speed at which the liquid B prepolymer is injected into the material A cavity tube is 100 ml / h.

[0022] In the aforementioned method for preparing a 3D printed plastic scintillator, in step 4), the liquid B prepolymer is injected into the cavity tube of the material A and polymerized by heating: first, the temperature in the sealed container is raised to 110°C at a rate of 5°C per hour and then maintained for 120 hours, and then the temperature in the sealed container is lowered to room temperature at a rate of 5°C per hour, and finally a 3D printed new plastic scintillator is obtained.

[0023] The beneficial effects of the present invention are:

[0024] 1) The present invention divides the plastic substrate, the luminescent material 2,5-diphenyloxazole (PPO) and the wave shifter 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP) into two parts, one of which is directly printed into a cavity tube with left and right through cavities through 3D printing technology. The shape and size of the scintillator can be customized according to the actual needs of production work. For plastic scintillators that require special shapes and small outputs, there is no need to prepare additional molds, which saves the cost and time of the mold preparation process, simplifies the plastic scintillator preparation process, and reduces the cost of plastic scintillator preparation; the other part is added with high atomic number material ZnO nanoparticles as ray capture materials and auxiliary scintillators and injected into the 3D printed cavity tube, thereby increasing the light yield and improving the photon conduction efficiency.

[0025] 2) The end face of the 3D-printed cavity tube of the present invention is used in conjunction with the placement direction of the photomultiplier tube, eliminating the intermediate component of the light-guiding glass, simplifying the instrument structure, reducing the light transmission and collection path, and reducing the escape of photons; at the same time, there is a refractive index difference between the external 3D-printed polystyrene plastic scintillator shell and the internally injected optical fiber core with high atomic number material ZnO nanoparticles, and the photons generated by the irradiation of the rays will be collected in the inner core of the optical fiber and transmitted to the coupled photomultiplier tube, thereby improving the transmission efficiency of the photons.

[0026] 3) The scintillator optical fiber prepared by the method of the present invention has two photon generation pathways: Path 1: PPO is used as the first scintillator to absorb γ-ray radiation energy, and the π electrons of the benzene ring in PPO are excited and then retreat to stimulate fluorescence, and POPOP absorbs the fluorescence excited by PPO, and the fluorescence wavelength moves to the range matching the photomultiplier tube; Path 2: ZnO is used as a high-energy ray capture material to absorb γ-ray radiation energy, and after being irradiated, it emits 380-400mm ultraviolet light, which is close to the wavelength of light emitted by the traditional PPO scintillator, and POPOP absorbs the fluorescence excited by ZnO, and the fluorescence wavelength moves to the range matching the photomultiplier tube; thereby increasing the light generation amount, and compared with the traditional scintillator without adding ZnO, the total light output of the present invention is increased by 9%, which is a relatively significant improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of the 3D printed new plastic scintillator of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with embodiments and drawings.

[0029] Example 1

[0030] This embodiment is a method for preparing a 3D printed plastic scintillator, comprising the following steps:

[0031] 1) Dissolve 2,5-diphenyloxazole and 1,4-bis(5-phenyl-2-oxazolyl)benzene in a certain proportion in a styrene-maleic anhydride copolymer and mix them evenly to obtain a liquid A; wherein the mass fraction concentration of 2,5-diphenyloxazole (PPO) is 0.6-1.2%, and the mass fraction concentration of 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP) is 0.01-0.03%.

[0032] 2) The liquid A is heated and polymerized to form a solid material A, and then the solid material A is added to a twin-screw extruder, melt-extruded and granulated, and then the obtained material A particles are used for 3D printing to form a material A cavity tube with left and right through cavities; the temperature of the liquid A being heated and polymerized to form the solid material A is 140-150°C, and the polymerization time is 48h; the parameters of the melt extrusion granulation are a melt flow rate (190°C, based on 2.16kg) of 1.25g / 10min, and the end face cavity diameter size of the obtained material A cavity tube is 0.01m.

[0033] 3) Dissolve ZnO nanoparticles, 2,5-diphenyloxazole and 1,4-bis(5-phenyl-2-oxazolyl)benzene in a certain proportion in styrene-maleic anhydride copolymer and mix them evenly to obtain liquid B; wherein the mass fraction concentration of ZnO nanoparticles is 8-12%, the mass fraction concentration of 2,5-diphenyloxazole (PPO) is 0.6-1.2%, and the mass fraction concentration of 1,4-bis(5-phenyl-2-oxazolyl)benzene is 0.01-0.03%.

[0034] 4) After prepolymerizing liquid B, inject it into a sealed container, inject nitrogen to expel the air, then slowly inject the liquid B prepolymer into the cavity tube of material A, and then heat it up to polymerize it, so as to obtain a 3D printed new plastic scintillator. The liquid B prepolymer temperature is heated to 55°C, and the temperature is maintained for 36 hours; then the temperature is raised to 95°C at a rate of 5°C / h and maintained for 120 hours; the speed of injecting the liquid B prepolymer into the cavity tube of material A is 100ml / h. After the liquid B prepolymer is injected into the cavity tube of material A, the temperature is raised to polymerize as follows: first, the temperature in the sealed container is raised to 110°C at a rate of 5°C per hour and maintained for 120 hours, and then the temperature in the sealed container is lowered to room temperature at a rate of 5°C per hour, and finally a 3D printed new plastic scintillator is obtained.

[0035] Example 2

[0036] This embodiment adopts the preparation method described in Example 1 to prepare a new type of 3D printed plastic scintillator. The specific method is as follows: first, 10g PPO and 2g POPOP are dissolved in 1000g styrene-maleic anhydride copolymer, ultrasonically oscillated for 3 minutes to dissolve the components, and then ultrasonicated for 10 minutes to mix the materials evenly to obtain a transparent A liquid. Then, the liquid A liquid is heated to 95°C, kept warm for 120 hours, and polymerized to form a solid A material; then, the solid A material is added to a twin-screw extruder, the preparation wire width is set to 1.75mm, and the solid A material is melt-extruded to prepare a wire. The obtained A material particles are then used for 3D printing to form an A material cavity tube with a left and right through cavity. Taking an ordinary rectangular scintillator as an example, the left side is the photomultiplier tube detection surface, and the top surface is the gamma ray detection surface. Then the A material cavity tube is a fiber-like structure, that is, a cube (size 0.9m*0.2m*0.1m) with a cylindrical space evenly distributed from left to right inside. Figure 1 shown.

[0037] 10g PPO and 2g POPOP were dissolved in 1000g styrene, and 100g ZnO nanoparticles were added. Ultrasonic oscillation was performed for 3min to mix the components evenly to obtain a transparent B liquid. The B liquid was then heated to 70°C and kept warm for 48h for prepolymerization. After nitrogen was injected into the synthesis container to expel the air, the heated B liquid B material was slowly injected into the A material cavity tube at a rate of 100ml / h, and then the temperature in the synthesis container was raised to 110°C at a rate of 5°C per hour and maintained for 120h; then the temperature in the container was lowered to room temperature at a rate of 5°C per hour, solidified and polymerized, and finally a 3D printed new plastic scintillator was obtained.

[0038] Example 3

[0039] This example is to investigate the light yield and light conductivity of the 3D printed new plastic scintillator prepared by the method of the present invention. The scintillator used for investigation in this example includes the 3D printed new plastic scintillator prepared in Example 2 and the existing plastic scintillator used in the gamma-ray method coal gangue identification equipment for coal mine conditions listed in the background technology of this application as a comparison (Comparative Example 1) (size is 1m*0.2m*0.1m).

[0040] The 3D printed new plastic scintillator prepared in Example 2 was connected to the side and the photomultiplier tube detection surface, and the top surface was the γ-ray detection surface, and a γ-ray method coal gangue identification device was prepared. The device and the comparison device were used to detect the same coal mine location, and the results are shown in Table 1.

[0041] Table 1. Light yield of 3D printed new plastic scintillators

[0042]

[0043] It can be seen from the results in Table 1 that when the same counting rate is achieved in the same scene, the required scintillator length can be shortened by about 10%. At the same time, the width and height of the scintillator do not need to be changed compared with the traditional scintillator, and it can be directly adapted to the existing photoelectric port, which effectively improves the passability and portability of the gamma-ray coal gangue identification equipment.

[0044] Example 4

[0045] This example investigates the effect of adding ZnO nanoparticles on the light yield of the prepared 3D printed new plastic scintillator.

[0046] In this embodiment, there are two types of scintillators used for investigation, one is the 3D printed new plastic scintillator prepared in Example 2, and the other is a 3D printed new plastic scintillator without adding ZnO nanoparticles for comparison (Comparative Example 2). The preparation method of the comparative scintillator is consistent with the scintillator preparation method in Example 2 except that ZnO nanoparticles are not added. The size of the prepared scintillators is 0.9m*0.2m*0.1m.

[0047] The two scintillators were connected to photomultiplier tubes respectively, and corresponding γ-ray coal gangue identification devices were prepared respectively. These devices were used to detect the same coal mine location, and the results are shown in Table 2.

[0048] Table 2. Effect of ZnO nanoparticles on the light yield of the prepared 3D printed new plastic scintillator

[0049]

[0050] It can be seen from the results in Table 2 that the light yield of the 3D printed new plastic scintillator with the addition of ZnO nanoparticles is increased by about 4% compared with the 3D printed new plastic scintillator without the addition of ZnO nanoparticles, indicating that the addition of ZnO nanoparticles improves the light yield of the plastic scintillator.

[0051] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view. In addition, it should be understood that although this specification is described in accordance with the implementation mode, it does not include only one technical solution. This narrative mode of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in the embodiments can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a 3D printed plastic scintillator, characterized in that: The steps include: 1) Dissolve 2,5-diphenyloxazole and 1,4-bis(5-phenyl-2-oxazolyl)benzene in a certain proportion in styrene-maleic anhydride copolymer, mix well, and obtain liquid A; 2) heating liquid A to polymerize to form solid material A, then adding the solid material A into a twin-screw extruder, melt-extrude and granulate, and then using the obtained material A particles for 3D printing to form a material A cavity tube with left and right through cavities; 3) Dissolve ZnO nanoparticles, 2,5-diphenyloxazole and 1,4-bis(5-phenyl-2-oxazolyl)benzene in a certain proportion in styrene-maleic anhydride copolymer, mix well, and obtain liquid B; 4) After prepolymerizing liquid B, inject it into a sealed container, inject nitrogen to expel the air, and then slowly inject the liquid B prepolymer into the cavity tube of material A, and then heat and polymerize to obtain a new type of 3D printed plastic scintillator.

2. The method for preparing a 3D printed plastic scintillator according to claim 1, characterized in that: In step 1), in the liquid A, the mass fraction concentration of 2,5-diphenyloxazole is 0.6-1.2%, and the mass fraction concentration of 1,4-bis(5-phenyl-2-oxazolyl)benzene is 0.01-0.03%.

3. The method for preparing a 3D printed plastic scintillator according to claim 2, characterized in that: In the liquid A, the mass fraction concentration of 2,5-diphenyloxazole is 1%, and the mass fraction concentration of 1,4-bis(5-phenyl-2-oxazolyl)benzene is 0.02%.

4. The method for preparing a 3D printed plastic scintillator according to claim 1, characterized in that: In step 2), the temperature at which the liquid A is heated and polymerized to form the solid material A is 140-150° C., and the polymerization time is 48 hours; the melt flow rate of the melt extrusion granulation is 1.25 g / 10 min.

5. The method for preparing a 3D printed plastic scintillator according to claim 1, characterized in that: In step 2), the end face cavity diameter of the obtained A material cavity tube is 10 mm.

6. The method for preparing a 3D printed plastic scintillator according to claim 1, characterized in that: In step 3), in the liquid B, the mass fraction concentration of ZnO nanoparticles is 8-12%, the mass fraction concentration of 2,5-diphenyloxazole is 0.6-1.2%, and the mass fraction concentration of 1,4-bis(5-phenyl-2-oxazolyl)benzene is 0.01-0.03%.

7. The method for preparing a 3D printed plastic scintillator according to claim 6, characterized in that: In the liquid B, the mass fraction concentration of ZnO nanoparticles is 10%, the mass fraction concentration of 2,5-diphenyloxazole is 1%, and the mass fraction concentration of 1,4-bis(5-phenyl-2-oxazolyl)benzene is 0.02%.

8. The method for preparing a 3D printed plastic scintillator according to claim 1, characterized in that: In step 4), the prepolymerization of liquid B is as follows: liquid B is heated to 55°C and maintained at this temperature for 36 hours; then the temperature is raised to 95°C at a rate of 5°C per hour and maintained for 120 hours.

9. The method for preparing a 3D printed plastic scintillator according to claim 1, characterized in that: In step 4), the speed of injecting the liquid B prepolymer into the cavity tube of material A is 100 ml / h.

10. The method for preparing a 3D printed plastic scintillator according to claim 1, characterized in that: In step 4), after the liquid B prepolymer is injected into the cavity tube of material A, the procedure of temperature-raising polymerization is as follows: first, the temperature in the sealed container is raised to 110°C at a rate of 5°C per hour and then maintained for 120 hours, and then the temperature in the sealed container is lowered to room temperature at a rate of 5°C per hour, and finally a new type of plastic scintillator is obtained by 3D printing.

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