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CN-121975204-A - Irradiation-resistant sealing composition based on end group functionalized elastomer

CN121975204ACN 121975204 ACN121975204 ACN 121975204ACN-121975204-A

Abstract

The invention discloses a radiation-resistant sealing composition based on a terminal group functionalized elastomer, and a preparation method and application thereof, and belongs to the technical field of high polymer materials and radiation protection. The composition comprises, by weight, 100 parts of a terminal group functionalized elastomer, 15-60 parts of a radiation-resistant filler, 1-8 parts of a cross-linking agent and 0.5-5 parts of a processing aid, wherein the terminal group functionalized elastomer is modified by hydroxyl-terminated polybutadiene or fluorinated elastomer containing a naphthalene ring, an anthracene ring or a phenanthrene ring as a terminal group modifier, and the radiation-resistant filler comprises a composite system of a radiation shielding filler and a free radical capturing filler. The invention combines the conjugate structure design of the molecular terminal and the synergistic effect of the composite filler, so that the sealing material can remarkably improve the high-dose irradiation resistance, the thermal stability and the compression permanent deformation resistance while maintaining good processing and mechanical properties, and is particularly suitable for sealing systems in high-end fields such as nuclear reactors, spacecrafts, medical equipment and the like.

Inventors

  • SU YOUXUE

Assignees

  • 苏有学

Dates

Publication Date
20260505
Application Date
20260128

Claims (10)

  1. 1. A radiation-resistant sealing composition based on a terminal group functionalized elastomer is characterized by comprising the following components in parts by weight: 100 parts of end group functionalized elastomer; 15-60 parts of radiation-resistant filler; 1-8 parts of cross-linking agent; 0.5-5 parts of processing aid; Wherein the end group functionalized elastomer is obtained by end group modification of hydroxyl-terminated polybutadiene or fluorinated elastomer by a benzene ring-containing end group modifier, and the end group modifier is selected from amine or alcohol compounds containing naphthalene ring, anthracene ring or phenanthrene ring structures.
  2. 2. The radiation-resistant sealing composition based on end-group functionalized elastomer according to claim 1, wherein the end-group functionalized elastomer is prepared by dissolving a hydroxyl-terminated polybutadiene or fluorinated elastomer in an organic solvent, adding a benzene ring-containing end-group modifier, reacting at 40-80 ℃ for 2-8 hours in the presence of a catalyst, and then precipitating, washing and drying.
  3. 3. The radiation-resistant sealing composition based on end-group functionalized elastomer according to claim 2, wherein the hydroxyl-terminated polybutadiene has a number average molecular weight of 2000-10000 g/mol and a hydroxyl value of 0.5-2.0 meq/g, and the fluorinated elastomer is a copolymer of vinylidene fluoride and hexafluoropropylene and has a fluorine content of 55-70 wt%.
  4. 4. The radiation-resistant sealing composition based on end-group functionalized elastomer according to claim 1, wherein the radiation-resistant filler comprises a composite system of a radiation-shielding filler and a radical trapping filler, wherein the radiation-shielding filler is selected from at least one of nano tungsten, nano tantalum, nano bismuth oxide or carbide, and the radical trapping filler is selected from at least one of nano cerium oxide, nano titanium oxide, fullerene or carbon nanotube.
  5. 5. The radiation-resistant sealing composition based on end-group functionalized elastomer according to claim 4, wherein the weight ratio of the radiation shielding filler to the free radical trapping filler is 3:1 to 8:1, the radiation-resistant filler has an average particle size of 20-200 nm and a specific surface area of 30-200 m2/g.
  6. 6. The radiation-resistant sealing composition based on end-group functionalized elastomer according to claim 1, wherein the crosslinking agent is a peroxide crosslinking agent selected from at least one of dicumyl peroxide, di-tert-butyl peroxide or bis (tert-butylperoxyisopropyl) benzene.
  7. 7. The radiation-resistant sealing composition based on end-group functionalized elastomer according to claim 1, wherein the processing aid comprises a complex system of processing oil, release agent and anti-aging agent, wherein the processing oil is selected from at least one of paraffinic oil, naphthenic oil or silicone oil, the release agent is selected from at least one of zinc stearate, calcium stearate or silicone release agent, and the anti-aging agent is selected from at least one of hindered phenols, phosphites or benzotriazoles.
  8. 8. A process for the preparation of a radiation resistant sealing composition based on end group functionalized elastomer according to any one of claims 1 to 7, characterized in that it comprises the following steps: Step 1, preparing a terminal group functionalized elastomer, namely dissolving hydroxyl-terminated polybutadiene or fluorinated elastomer in an organic solvent, adding a benzene ring-containing terminal group modifier and a catalyst, reacting for 2-8 hours at 40-80 ℃, and then precipitating, washing and drying to obtain the terminal group functionalized elastomer; Step 2, mixing, namely mixing the end group functionalized elastomer, the radiation-resistant filler and the processing aid obtained in the step 1 in an internal mixer at 50-90 ℃ for 10-30 minutes to obtain a rubber compound; And step 3, crosslinking, namely uniformly mixing the rubber compound obtained in the step 2 with a crosslinking agent in an open mill at 40-60 ℃, and then performing molding and vulcanization treatment, wherein the vulcanization temperature is 150-180 ℃ and the vulcanization time is 10-30 minutes.
  9. 9. Use of a radiation resistant sealing composition based on end group functionalized elastomers according to any of claims 1to 7 in nuclear reactor sealing systems, spacecraft sealing parts or medical equipment radiation shielding seals.
  10. 10. A sealing article, characterized in that it is obtained by molding and curing a radiation-resistant sealing composition based on a functionalized elastomer with end groups according to any one of claims 1 to 7, said sealing article being an O-ring, gasket, valve seat or dynamic seal.

Description

Irradiation-resistant sealing composition based on end group functionalized elastomer Technical Field The invention relates to the technical field of high polymer materials and radiation protection, in particular to a radiation-resistant sealing composition based on a terminal group functionalized elastomer, and particularly relates to a radiation-resistant sealing composition based on a terminal group functionalized elastomer, and a preparation method and application thereof. Background With the rapid development of the fields of nuclear energy technology, aerospace technology, medical radiation equipment and the like, higher and higher requirements are put on sealing materials working in radiation environments. These materials need to maintain not only excellent sealing properties, but also good physical and mechanical properties and dimensional stability under the action of ionizing radiation (such as gamma rays, X rays, electron beams, etc.) for a long period of time. In the prior art, at present, fluororubber, silicon rubber, ethylene propylene rubber and the like are mainly adopted as matrix materials for the radiation-resistant sealing material. Fluororubbers exhibit better radiation resistance due to their higher fluorine content and carbon-fluorine bond energy. The silicone rubber has a certain resistance to irradiation due to the high bond energy of its Si-O bonds (about 460 kJ/mol). Chinese patent CN115746567A discloses a sealing material with low escape and long service life, a preparation method and application thereof, wherein the raw material components of the sealing material comprise 100 parts by mass of special silicon rubber, 30-45 parts by mass of reinforcing white carbon black, 4-8 parts by mass of heat-resistant auxiliary agent, 2-3 parts by mass of colorant, 5-10 parts by mass of radiation protection agent and 0.5-1.0 part by mass of peroxide curing agent. The sealing material provided by the invention has the advantages of few vacuum escaping substances, small compression permanent deformation, good radiation resistance, excellent comprehensive performance and long service life, and is suitable for sealing of long-term on-orbit space vehicles. The sealing material adopts phenyl silicone rubber as a main body and barium sulfate as a radiation-proof agent, and is suitable for sealing space vehicles. However, such materials still have significant performance degradation problems in long-term high-dose radiation environments, mainly manifested by problems of loss of elasticity, radical-induced oxidative degradation, gas evolution, and the like, caused by increased crosslinking density. For example, fluororubbers are susceptible to cleavage of the main chain C-C bonds and C-F bonds under high doses of gamma radiation, generating a large number of free radicals which not only initiate further cleavage (degradation) of the polymer chains, but also combine with one another to cause excessive crosslinking (hardening), a competing mechanism being a central cause of performance degradation. Although the Si-O bond energy of the silicone rubber is high, the organic side chains (such as methyl and phenyl) of the silicone rubber are easy to undergo dehydrogenation, oxidation and other reactions under radiation, so that the chains are broken and crosslinked, and meanwhile, the filler network of the silicone rubber is damaged by the radiation, so that the reinforcement is invalid. The technical bottlenecks include (1) unstable material performance caused by crosslinking and degradation competition mechanism caused by radiation, (2) lack of effective radiation energy dissipation path to cause accumulated damage easily inside the material, (3) increased compression set after irradiation and reduced sealing performance in dynamic sealing application, and (4) high filler content can improve radiation resistance but worsen processability and mechanical properties. In particular, to obtain a sufficient radiation shielding effect, it is often necessary to add large amounts (typically >100 parts) of high atomic number (high Z) fillers such as lead powder, barium sulfate, tungsten powder, etc. The viscosity of the sizing material can be seriously increased, so that the mixing difficulty and the energy consumption are increased, the fluidity is poor during extrusion or compression molding, and the product is easy to generate defects. Therefore, how to maximize the irradiation resistance of the material under the condition of limited filler addition amount becomes a technical key. The research and development necessity is that aiming at the problems, the novel irradiation-resistant sealing composition is developed, the irradiation resistance of the material can be obviously improved while the good processing performance and the mechanical performance are maintained, and the novel irradiation-resistant sealing composition has important significance in the high-end application fields such as a nuclear power stati