The crystalline phase transition of aliphatic nylon 10/10 has been investigated on the basis of the simultaneous measurement of wide-angle and small-angle X-ray scatterings, the infrared spectral measurement and the m...The crystalline phase transition of aliphatic nylon 10/10 has been investigated on the basis of the simultaneous measurement of wide-angle and small-angle X-ray scatterings, the infrared spectral measurement and the molecular dynamics calculation. An interpretation of infrared spectra taken for a series of nylon samples and the corresponding model compounds was successfully made, allowing us to assign the infrared bands of the planar-zigzag methylene segments reasonably. As a result the methylene segmental parts of molecular chains were found to experience an order-to-disorder transition in the Brill transition region, where the intermolecular hydrogen bonds are kept alive although the bond strength becomes weaker at higher temperature. The small-angle X-ray scattering data revealed a slight change in lamellar stacking mode in the transition region. The crystal structure has been found to change more remarkably in the temperature region immediately below the melting point, where the conformationally disordered chains experienced drastic rotational and translational motions without any constraints by hydrogen bonds, and the lamellar thickness increased largely along the chain axis. These experimental results were reasonably reproduced by the molecular dynamics calculation performed at the various temperatures.展开更多
The microstmcture evolution of plastic-bonded explosives （PBXs） after thermal stimulus plays a key role in PBX performance. In this paper, the nanoscale pores of thermal-treated octahydro-1,3,5,7-tetranitro-1,3,5,7 ...The microstmcture evolution of plastic-bonded explosives （PBXs） after thermal stimulus plays a key role in PBX performance. In this paper, the nanoscale pores of thermal-treated octahydro-1,3,5,7-tetranitro-1,3,5,7 tetrazocine （HMX）- based PBXs with different HMX particle sizes [approximately 40 （FLIP） and 100 μm （LHP）] were measured using small- angle X-ray scattering （SAXS）. No obvious pore variations were found in the LHP samples heated at 160 ℃ for 6 h, whereas the amount of pores of FHP decreased when subjected to 160 ℃ for 6 h. At 180 ℃, the average pore radii of FHP and LHP decreased from approximately 45 nm to 25 nm, and the total pore volume increased distinctively because of phase transformation. The LHP sample reached a high level of pore content after being held at 180 ℃ for 1 h, whereas FHP required 3 h. Both FHP and LHP had relatively high pore volumes when subjected to 200 ℃ for 1 and 3 h.展开更多
基金This study was supported financially by the MEXT "Collaboration with Local Communities" Project (2005-2009).
文摘The crystalline phase transition of aliphatic nylon 10/10 has been investigated on the basis of the simultaneous measurement of wide-angle and small-angle X-ray scatterings, the infrared spectral measurement and the molecular dynamics calculation. An interpretation of infrared spectra taken for a series of nylon samples and the corresponding model compounds was successfully made, allowing us to assign the infrared bands of the planar-zigzag methylene segments reasonably. As a result the methylene segmental parts of molecular chains were found to experience an order-to-disorder transition in the Brill transition region, where the intermolecular hydrogen bonds are kept alive although the bond strength becomes weaker at higher temperature. The small-angle X-ray scattering data revealed a slight change in lamellar stacking mode in the transition region. The crystal structure has been found to change more remarkably in the temperature region immediately below the melting point, where the conformationally disordered chains experienced drastic rotational and translational motions without any constraints by hydrogen bonds, and the lamellar thickness increased largely along the chain axis. These experimental results were reasonably reproduced by the molecular dynamics calculation performed at the various temperatures.
基金State Key Laboratory for Modification of Chemical Fibers and Polymer Materials in Donghua University(LK1506)National Natural Science Foundation of China(11305249)National Basic Research Program of China(2011CB606104,2011CB605604)~~
基金supported by the National Natural Science Foundation of China(Grant Nos.11205137,11079043,and 11302199)
文摘The microstmcture evolution of plastic-bonded explosives （PBXs） after thermal stimulus plays a key role in PBX performance. In this paper, the nanoscale pores of thermal-treated octahydro-1,3,5,7-tetranitro-1,3,5,7 tetrazocine （HMX）- based PBXs with different HMX particle sizes [approximately 40 （FLIP） and 100 μm （LHP）] were measured using small- angle X-ray scattering （SAXS）. No obvious pore variations were found in the LHP samples heated at 160 ℃ for 6 h, whereas the amount of pores of FHP decreased when subjected to 160 ℃ for 6 h. At 180 ℃, the average pore radii of FHP and LHP decreased from approximately 45 nm to 25 nm, and the total pore volume increased distinctively because of phase transformation. The LHP sample reached a high level of pore content after being held at 180 ℃ for 1 h, whereas FHP required 3 h. Both FHP and LHP had relatively high pore volumes when subjected to 200 ℃ for 1 and 3 h.
