In this work, the polyacrylonitrile containing gadolinium nanofibers for thermal neutron protection were successfully fabricated by electrospunning and followed by in situ self-polymerization. Scanning electron micros...In this work, the polyacrylonitrile containing gadolinium nanofibers for thermal neutron protection were successfully fabricated by electrospunning and followed by in situ self-polymerization. Scanning electron microscopy(SEM) and energy-dispersive spectroscopy(EDS) results show that there are no beads on the smooth surface of the nanofibers and gadolinium elements are uniformly dispersed in the matrix. The thermal analysis and FTIR results prove that gadolinium methacrylate is induced in situ selfpolymerization during the heat treatment. The leaching rate of Gd^(3+) decreases from 79.97% to 10.74% tested by lowfield nuclear magnetic resonance(LF-NMR) method after the self-polymerization of gadolinium methacrylate in the matrix when the nanofibers were immersed in water for7 days. The thermal neutron shielding analysis calculated by MCNP program shows that above 99% thermal neutrons are absorbed when traveling through the 2-mm-thick polyacrylonitrile containing gadolinium nanofibers.展开更多
Hydrogen nuclear magnetic resonance(H1-NMR) and X-ray diffractometer(XRD) were used to characterize the molecular and crystal structure of lead methacrylate [Pb(MAA)_(2)] which was produced by the double decomposition...Hydrogen nuclear magnetic resonance(H1-NMR) and X-ray diffractometer(XRD) were used to characterize the molecular and crystal structure of lead methacrylate [Pb(MAA)_(2)] which was produced by the double decomposition reaction of lead oxide and methacrylic acid.Isothermal analysis and Kelen-T(u|")dos(K-T) method were used to study the self-polymerization kinetic and the monomer reactivity ratios of Pb(M A A)_(2) and methyl methacrylate(MMA),respectively.By the ternary polymerization method of bulk casting using MMA,Pb(MAA)_(2) and gadolinium methacrylate(Gd(MAA)_(3)) as monomers,we prepared the plexiglass which have neutron and X-ray protection property.The results show that the polymerization rate(R_(p)) is expressed as Rp=K[M]^(1.02)[I]^(0.37) below the 10% conversion rate at 70℃,where K is the polymerization rate constant.And in the N,N-dimethylformamide(DMF) solution,the activation energy required for Pb(MAA)_(2) to initiate self-polymerization by the free radicals is 74.99 kJ·mol^(-1).The reactivity ratios of r1 [Pb(MAA)_(2)] and r2(MMA) are 3.767 and0.166.As the thickness of the material increases,the X-ray and thermal neutron shielding ability of the plexiglass containing gadolinium and lead is getting better and better.展开更多
基金financially supported by Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYLX_1337)the Excellent Doctorial Dissertations Fund of Yangzhou University
文摘In this work, the polyacrylonitrile containing gadolinium nanofibers for thermal neutron protection were successfully fabricated by electrospunning and followed by in situ self-polymerization. Scanning electron microscopy(SEM) and energy-dispersive spectroscopy(EDS) results show that there are no beads on the smooth surface of the nanofibers and gadolinium elements are uniformly dispersed in the matrix. The thermal analysis and FTIR results prove that gadolinium methacrylate is induced in situ selfpolymerization during the heat treatment. The leaching rate of Gd^(3+) decreases from 79.97% to 10.74% tested by lowfield nuclear magnetic resonance(LF-NMR) method after the self-polymerization of gadolinium methacrylate in the matrix when the nanofibers were immersed in water for7 days. The thermal neutron shielding analysis calculated by MCNP program shows that above 99% thermal neutrons are absorbed when traveling through the 2-mm-thick polyacrylonitrile containing gadolinium nanofibers.
基金financially supported by the Aviation Science Fund(No.2017ZF25)the Graduate Research Innovation Fund of Yangzhou University(No.XKYCX19066)。
文摘Hydrogen nuclear magnetic resonance(H1-NMR) and X-ray diffractometer(XRD) were used to characterize the molecular and crystal structure of lead methacrylate [Pb(MAA)_(2)] which was produced by the double decomposition reaction of lead oxide and methacrylic acid.Isothermal analysis and Kelen-T(u|")dos(K-T) method were used to study the self-polymerization kinetic and the monomer reactivity ratios of Pb(M A A)_(2) and methyl methacrylate(MMA),respectively.By the ternary polymerization method of bulk casting using MMA,Pb(MAA)_(2) and gadolinium methacrylate(Gd(MAA)_(3)) as monomers,we prepared the plexiglass which have neutron and X-ray protection property.The results show that the polymerization rate(R_(p)) is expressed as Rp=K[M]^(1.02)[I]^(0.37) below the 10% conversion rate at 70℃,where K is the polymerization rate constant.And in the N,N-dimethylformamide(DMF) solution,the activation energy required for Pb(MAA)_(2) to initiate self-polymerization by the free radicals is 74.99 kJ·mol^(-1).The reactivity ratios of r1 [Pb(MAA)_(2)] and r2(MMA) are 3.767 and0.166.As the thickness of the material increases,the X-ray and thermal neutron shielding ability of the plexiglass containing gadolinium and lead is getting better and better.
