阅读说明：本技术 一种耐高温改性聚乙烯基屏蔽材料及其制备方法 (High-temperature-resistant modified polyethylene-based shielding material and preparation method thereof ) 是由 李晓玲 陈艳 陈淼 余明 安然 张多飞 吴荣俊 于 2020-12-22 设计创作，主要内容包括：本发明提供一种耐高温改性聚乙烯基屏蔽材料,按重量份数计,其原料包括：高密度聚乙烯10～12份,接枝改性超高分子量聚乙烯6～8份,辐射屏蔽物质80～85份,加工助剂0.5～3份。本发明提供的耐高温改性聚乙烯基屏蔽材料,能够耐受中破口失水事故下190℃以上的高温,并且依然能够保持屏蔽结构的完整性和屏蔽防护的有效性,是核电站反应堆核岛区域良好的辐射屏蔽材料。将该材料应用于多个核电站进行试验验证,证明本发明提供的耐高温改性聚乙烯基屏蔽材料完全可以满足核电站正常运行及中破口失水事故等工况下整个寿期的辐射防护设计要求。(The invention provides a high-temperature-resistant modified polyethylene-based shielding material which comprises the following raw materials in parts by weight: 10-12 parts of high-density polyethylene, 6-8 parts of graft modified ultrahigh molecular weight polyethylene, 80-85 parts of radiation shielding substances and 0.5-3 parts of processing aids. The high-temperature-resistant modified polyethylene-based shielding material provided by the invention can resist the high temperature of more than 190 ℃ under the medium-breach water loss accident, can still keep the integrity of a shielding structure and the effectiveness of shielding protection, and is a good radiation shielding material for the nuclear island area of a nuclear power plant reactor. The material is applied to a plurality of nuclear power stations for test verification, and the high-temperature-resistant modified polyethylene-based shielding material provided by the invention can completely meet the radiation protection design requirements of the nuclear power station in the whole service life under the working conditions of normal operation, medium-break water loss accidents and the like.)

1. The high-temperature-resistant modified polyethylene-based shielding material is characterized by comprising the following raw materials in parts by weight:

10-12 parts of high-density polyethylene,

6-8 parts of graft modified ultra-high molecular weight polyethylene,

80-85 parts of a radiation shielding material,

0.5-3 parts of a processing aid.

2. The high-temperature-resistant modified polyethylene-based shielding material as claimed in claim 1, wherein the high-density polyethylene has a particle size of 60 to 80 μm and a density of more than 0.95g/cm³。

3. The high temperature resistant modified polyethylene based shielding material according to claim 1 or 2, wherein the graft-modified ultra high molecular weight polyethylene is maleic anhydride-modified ultra high molecular weight polyethylene.

4. The high-temperature-resistant modified polyethylene-based shielding material as claimed in any one of claims 1 to 3, wherein the graft-modified ultrahigh molecular weight polyethylene comprises the following raw materials in parts by weight:

5.4 to 7.7 parts of ultra-high molecular weight polyethylene,

0.12 to 0.2 part of maleic anhydride,

0.12-0.2 parts of dicumyl peroxide.

5. The high-temperature-resistant modified polyethylene-based shielding material as claimed in claim 4, wherein the particle size of the ultra-high molecular weight polyethylene is 60-80 μm, and the molecular weight is more than 200 ten thousand; the purity of the maleic anhydride is more than 99%.

6. The high-temperature-resistant modified polyethylene-based shielding material as claimed in any one of claims 1 to 5, wherein the radiation shielding substance comprises, in parts by weight:

78-82 parts of lead powder,

2-3 parts of gadolinium oxide powder.

7. The high-temperature-resistant modified polyethylene-based shielding material as claimed in any one of claims 1 to 6, wherein the lead powder has a particle size of 60 to 80 μm and an oxidation degree of not more than 5%; the particle size of the gadolinium oxide powder is 60-80 mu m.

8. The high temperature resistant modified polyethylene based shielding material as claimed in claim 1, wherein the processing aid comprises, in parts by weight:

0.5 to 2 parts of polyethylene wax,

0.5-1 part of stearic acid.

9. The method for preparing the high-temperature-resistant modified polyethylene-based shielding material as claimed in any one of claims 1 to 8, comprising:

and uniformly mixing the high-density polyethylene, the graft modified ultrahigh molecular weight polyethylene, the radiation shielding substance and the processing aid, extruding, and processing and molding.

10. The method for preparing the high temperature resistant modified polyethylene based shielding material according to claim 9, wherein the method for preparing the graft modified ultra-high molecular weight polyethylene comprises:

the preparation method comprises the steps of uniformly mixing the ultrahigh molecular weight polyethylene, the maleic anhydride and the dicumyl peroxide, then carrying out melt grafting, extruding granulation and grinding into powder.

Technical Field

The invention relates to the field of radiation-proof materials, in particular to a high-temperature-resistant modified polyethylene-based shielding material and a preparation method thereof.

Background

The reactor areas such as nuclear power stations and ship nuclear power devices need to be provided with radiation shielding materials, and the radiation shielding materials are mainly used for blocking and weakening neutrons, gamma rays and the like released by the reactors, a loop pipeline and the like, so that the radiation field dose rate of the shielding outer area meets the relevant requirements of radiation zoning, and the radiation safety of workers, equipment and the environment is guaranteed.

The radiation shielding material commonly used in nuclear power plants is concrete, but in local parts, such as a shielding door, a shielding wall, a pipeline access area and the like, light shielding materials such as polyethylene base or epoxy resin base and the like are adopted in consideration of the installation, protection, volume requirements and the like of a shielding body. Polyethylene has a high hydrogen content due to interaction between neutrons and substances, can effectively slow down neutrons by elastic scattering, and is generally preferred as a matrix material for a shielding material. However, a significant disadvantage of such polyethylene-based shielding materials is the relatively low heat distortion temperature, typically 85 ℃. Therefore, generally, the shielding material cannot normally work in a temperature environment above 100 ℃, which limits the application of the shielding material in a higher temperature environment, and particularly when a medium-break water loss accident occurs, the higher temperature (about 190 ℃) can cause softening, deformation, splashing and the like of the shielding material, so that the shielding effect of the shielding material is reduced or even loses efficacy, and thus, the radiation safety hazard is generated. If the common methods such as filler filling modification and the like are adopted, although the use temperature can be increased to a certain degree, the use requirement of 190 ℃ is still difficult to meet, and the shielding performance is greatly reduced due to the addition of a large amount of filler. Therefore, how to increase the use temperature of the polyethylene-based radiation shielding material on the basis of ensuring that the shielding performance is not reduced is a technical problem to be solved in the field.

Disclosure of Invention

Therefore, the technical problem to be solved by the present invention is to overcome the defect that the polyethylene-based shielding material in the prior art cannot resist high temperature, so as to provide a high temperature resistant modified polyethylene-based shielding material and a preparation method thereof.

In a first aspect, the invention provides a high temperature resistant modified polyethylene-based shielding material, which comprises the following raw materials in parts by weight:

10-12 parts of high-density polyethylene,

6-8 parts of graft modified ultra-high molecular weight polyethylene,

80-85 parts of a radiation shielding material,

0.5-3 parts of a processing aid.

Further, the high-density polyethylene has a particle size of 60-80 μm and a density of more than 0.95g/cm³。

Further, the graft-modified ultrahigh molecular weight polyethylene is maleic anhydride-modified ultrahigh molecular weight polyethylene.

Further, the graft modified ultrahigh molecular weight polyethylene comprises the following raw materials in parts by weight:

5.4 to 7.7 parts of ultra-high molecular weight polyethylene,

0.12 to 0.2 part of maleic anhydride,

0.12-0.2 parts of dicumyl peroxide.

Further, the particle size of the ultra-high molecular weight polyethylene is 60-80 μm, and the molecular weight is more than 200 ten thousand; the purity of the maleic anhydride is more than 99%.

Further, the radiation shielding material comprises, in parts by weight:

78-82 parts of lead powder,

2-3 parts of gadolinium oxide powder.

Further, the particle size of the lead powder is 60-80 μm, and the oxidation degree is not more than 5%; the particle size of the gadolinium oxide powder is 60-80 mu m.

Further, the processing aid comprises the following components in parts by weight:

0.5 to 2 parts of polyethylene wax,

0.5-1 part of stearic acid.

In a second aspect, the present invention provides a method for preparing the high temperature resistant modified polyethylene-based shielding material, comprising:

and uniformly mixing the high-density polyethylene, the graft modified ultrahigh molecular weight polyethylene, the radiation shielding substance and the processing aid, extruding, and processing and molding.

Further, the extrusion is carried out at 170-190 ℃ and 500 rpm.

Further, the extrusion is carried out in a twin screw extruder.

Further, the forming is performed in a press vulcanizer.

Further, the processing and forming are to plasticize the particles into the plate under the conditions of 170-190 ℃ and 5-7 MPa.

Further, the preparation method of the graft-modified ultrahigh molecular weight polyethylene comprises the following steps:

the preparation method comprises the steps of uniformly mixing the ultrahigh molecular weight polyethylene, the maleic anhydride and the dicumyl peroxide, then carrying out melt grafting, extruding granulation and grinding into powder.

Further, the melt grafting and the extrusion granulation are carried out under the conditions of 150-210 ℃ and 500 rpm.

The melt grafting and extrusion granulation are carried out in a twin-screw extruder.

The technical scheme of the invention has the following advantages:

1. the invention provides a high-temperature-resistant modified polyethylene-based shielding material which comprises the following raw materials: the radiation shielding material comprises high-density polyethylene, graft modified ultrahigh molecular weight polyethylene, a radiation shielding substance and a processing aid, wherein the high-density polyethylene is used as a base material, has higher density and melt flowability, and is beneficial to improving the shielding performance and the processing performance of the shielding material; because the ultrahigh molecular weight polyethylene and the high density polyethylene have the same element components and can keep the original shielding performance not to be reduced, the graft modified ultrahigh molecular weight polyethylene is a graft copolymer of the ultrahigh molecular weight polyethylene, the high temperature resistance of the material is effectively improved by block and graft copolymerization by utilizing the characteristics of higher melt strength, extremely insensitivity to thermal shearing and the like of the graft modified ultrahigh molecular weight polyethylene, so that the obtained polyethylene shielding material is basically in a gel state at high temperature, does not generate softening deformation under the action of no external force, effectively solves the use problem in high temperature environment, can effectively fuse radiation shielding substances by adding the graft modified ultrahigh molecular weight polyethylene, and enhances the mixing uniformity, the mechanical property and the like of a finished product on the basis of improving the comprehensive shielding capacity of neutrons and gamma rays of the shielding material, Radiation aging resistance, etc.; the composite shielding material has a good comprehensive shielding effect on fast neutrons, thermal neutrons and gamma rays of 1-3 MeV of a reactor.

2. The high-temperature-resistant modified polyethylene-based shielding material provided by the invention can resist the high temperature of more than 190 ℃ under the medium-breach water loss accident, can still keep the integrity of a shielding structure and the effectiveness of shielding protection, and is a good shielding material for the nuclear island area of a nuclear power plant reactor. The material is applied to a plurality of Hualongyi nuclear power stations for test verification, and the high-temperature-resistant modified polyethylene-based shielding material provided by the invention is proved to be capable of completely meeting the radiation protection design requirements of the nuclear power station in the whole service life under the working conditions of normal operation, medium-break water loss accidents and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a photograph of a high temperature resistant modified polyethylene-based shielding plate prepared according to example 1 of the present invention after a breach water loss accident simulation test;

fig. 2 is a photograph of a conventional polyethylene-based shield sheet commercially available after a crevasse loss accident simulation test.

Detailed Description

The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.

Sources of feedstock and apparatus

High Density Polyethylene (HDPE) from China petrochemical, 5000S, particle size of 60-80 μm, density of more than 0.95g/cm³；

The polyethylene with ultrahigh molecular weight is purchased from Yanshan petrochemical, M II, the particle size is 60-80 mu M, and the molecular weight is more than 200 ten thousand;

maleic anhydride, available from Shanghai Aladdin Biotechnology, Inc., M116389, with a purity of greater than 99%;

dicumyl peroxide, available from Shanghai Allan Biotechnology Ltd, D100480,

lead powder purchased from Zibo torch electromechanical equipment Limited liability company, Pb99.994, with the particle size of 60-80 μm and the oxidation degree of not more than 5%;

gadolinium oxide powder, purchased from Tianjin advanced materials science and technology limited, Gd2O3034351000, with a particle size of 60-80 μm;

polyethylene wax, available from Changzhou Rong ao chemical new materials, Inc., BP 2326;

calcium stearate, available from nojia plastification ltd, guan, NJ-026B;

a twin screw extruder, available from Nanjing BaoOhm rubber and plastic machinery Limited, model BM 65;

a high speed mixer, available from Wansheng drying equipments, Inc. of Changzhou city, model number GHJ-200;

a press vulcanizer available from the first rubber and plastic equipment ltd, model 3200T press, changzhou.

The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The raw materials or equipment used are all conventional products which can be obtained commercially, including but not limited to the raw materials or equipment used in the examples of the present application.

Example 1

A high-temperature resistant modified polyethylene-based shielding material comprises the following raw materials:

the preparation method of the high-temperature-resistant modified polyethylene-based shielding material comprises the following steps:

(1) taking a double-screw extruder as a continuous reactor, plasticizing, melting, dispersing and mixing, grafting, conveying a melt and the like at the temperature of 200 ℃ and the screw rotating speed of 500rpm on a mixture of polyethylene, maleic anhydride, a peroxide and other additives, cooling and drying an extrudate, cutting the extrudate into particles, grinding the particles into powder with the particle size of 60-80 mu m, and obtaining the graft modified ultrahigh molecular weight polyethylene;

(2) sequentially putting the graft modified ultrahigh molecular weight polyethylene, the high density polyethylene, the lead powder, the gadolinium oxide powder, the polyethylene wax and the calcium stearate into a high-speed stirrer, and fully mixing at the rotating speed of 900r/min to obtain a mixture;

(3) putting the mixture into a double-screw extruder, and heating, extruding, shearing and the like at 190 ℃ and 500rpm to complete extrusion to obtain an extruded material;

(4) the extruded material is put into a plate vulcanizing machine and is subjected to high-temperature high-pressure compression molding at 190 ℃ and 6Mpa to form a compact plate.

Example 2

A high-temperature resistant modified polyethylene-based shielding material comprises the following raw materials:

the preparation method of the high temperature resistant modified polyethylene-based shielding material is the same as that of example 1.

Example 3

A high-temperature resistant modified polyethylene-based shielding material comprises the following raw materials:

the preparation method of the high temperature resistant modified polyethylene-based shielding material is the same as that of example 1.

Example 4

A high-temperature resistant modified polyethylene-based shielding material comprises the following raw materials:

the preparation method of the high temperature resistant modified polyethylene-based shielding material is the same as that of example 1.

Examples of the experiments

The high temperature resistant modified polyethylene-based shielding materials prepared in reference examples 1 to 4 were subjected to performance tests, and test items, test results, and test methods are shown in table 1.

TABLE 1 Performance test results of high temperature-resistant modified polyethylene-based shielding materials

The test results in table 1 show that the high temperature resistant modified polyethylene-based shielding material provided by the invention has excellent properties, and particularly can keep the integrity and effectiveness of the shielding structure under the high temperature environment condition of 190 ℃. For comparison, the high temperature resistance of a common polyethylene shielding plate (high density polyethylene plate, product number: GQPJ-01, manufactured by york ship, heaven and earth ship equipment, jiangsu limited) sold in the market is detected under the same experimental conditions, and through observation, as shown in fig. 1, the high temperature resistant modified polyethylene shielding plate provided by the invention has no significant deformation, and no phenomena of softening and collapse occur, as shown in fig. 2, the commercially available plate has significant deformation, and softening and collapse occur, and the integrity and effectiveness of the shielding structure cannot be maintained.

The material is applied to a plurality of Hualongyi nuclear power stations for test verification, and the high-temperature resistant modified polyethylene-based shielding material provided by the invention can completely meet the requirements of normal operation and engineering application of the nuclear power stations.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.