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Relationship between free volume and mechanical properties of polyurethane irradiated by gamma rays |
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| Authors: | Heliang Sui Xueyong Liu Fachun Zhong Xiaoyan Li Baoyi Wang Xin Ju |
| Affiliation: | 1. Department of Physics, University of Science and Technology Beijing, Beijing, 100083, China 2. Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900, China 3. Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900, China 4. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100039, China |
| Abstract: | Polyurethane was irradiated at various gamma radiation doses up to 1,000 kGy at room temperature in nitrogen. Positron annihilation lifetime spectroscopy, tensile test and dynamic mechanical analysis were used to find the relationship between free volume and mechanical properties. An increase of the free volume fraction in soft segments (SS) and a decrease of the free volume fraction in hard segments (HS) during gamma radiation was observed and analyzed. The results showed that HS in polyurethane had the excellent resistance to gamma radiation, whereas SS had a tendency to degrade. The reason for the decrease of the strain at break and the ultimate tensile strength was analyzed, which showed the changes in the mechanical properties of polyurethane irradiated by gamma rays were mainly determined by the changes of free volume in SS. If the resistance properties of polyurethanes exposed to radiations need to be improved, SS should be paid more attention to. |
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