Studies Towards Novel Polyacrylic Acid/Metal Composite Radiation Shielding Materials

With the rapid development of human society, nuclear science and technology has been widely used in energy, industry, national defense and other areas, the threats of various radiation hazards upon the organisms and electronic components are becoming more and more serious, the developments of novel efficient radiation shielding materials have become one of the key research topics of nuclear technology. In recent years, some composite materials based on polymer resin substrate have shown a very broad application prospect in the field of aviation, medical equipment, health security and so on, due to its light weight, easy processing and economic cost. In this thesis, three kinds of new composite materials with good radiation shielding properties are prepared by using in situ polymerization of monomers chemically bonding with metal functional particles, the physical and radiation shielding properties of the materials are also characterized. The main contents of the research works are divided into the following three aspects:1. A series of poly(acrylic acid lead) resin materials with different formulations are prepared by thermal or UV initialized in situ polymerization and crosslinking respectively, followed by a second remolding step to form in compact structures. FTIR, SEM experiments are carried out to characterize the material's physcial properties. 137Cs and 60Co are used as the radiation sources, the shielding performances of composite materials are measured by data statistics using multi-channel gamma spectroscopy. The result shows that the y-ray shielding performance of poly(acrylic acid lead) resin material prepared by UV-initialization is obviously better than the one using thermal-initialization. The minimum half value thickness (HVT) of these novel materials can reach 3.80 cm,5.10 cm and 4.94 cm when the radiation energy is 0.662 MeV,1.17 MeV and 1.33 MeV respectively.2. A series of poly(acrylic acid gadolinium) resin materials with different formulations are prepared by UV initialized in situ polymerization, followed by a second remolding step to form in compact structures. FTIR, SEM experiments are carried out to characterize the material's physcial properties.238Pu,137Cs and 60Co are used as the radiation sources, the shielding performances of composite materials are measured by data statistics using multi-channel gamma spectroscopy. The influences of acrylic acid gadolinium content on the shielding performance are discussed. It concludes that materials containing the rare earth element, gadolinium, have a good shielding effect towards low energy y-ray, while have limited effects to medium energy y-ray. The neutron shielding performance are measured by using 241Am-Be as neutron source. Thermal neutron shielding rate can reach 80.65% when the material's thickness is 1.71 cm, but the shielding effect is meagre towards fast neutrons.3. Acrylic acid gadolinium/sodium alginate/acrylamide hydrogels are prepared by thermal induced in situ polymerization. Water retention performance at 40?, swelling properties in different environments, mechanical performance, shielding proterties towards neutron and low energy y-ray of the novel hydrogel are investigated. The result shows that the best percentage content of acrylic acid gadolinium in hydrogel is 2.65%, the corresponding water retention rate was 362.71%. The maximum swelling rate was 3045.03% when the hydrogel is immersed in deionized water environment at 25 ?. Elastic modulus can reach 1.25 MPa, the maximum tensile rate is 500%. The minimum half value thickness (HVT) of this hydrogel is 3.03 cm and 4.53 cm when the radiation energy is 79.9 keV and 167.7 keV respectively. Thermal neutron shielding rate can reach 73.67% when the hydrogel's thickness is 1.45 cm, but the shielding effect is meagre towards fast neutrons.