To investigate the thinning of the whole crust, and the contribution of the upper versus lower crust to the stretching since Cenozoic, we calculated the stretching factor of the northern margin of South China Sea with...To investigate the thinning of the whole crust, and the contribution of the upper versus lower crust to the stretching since Cenozoic, we calculated the stretching factor of the northern margin of South China Sea with data such as whole crustal thickness, depth of Cenozoic sedimentary basement and the horizontal displacement of faults. An isometric line drawing on whole crustal stretching factor is then obtained. Along the seismic Line 1530 in Baiyun sag, we also calculated the stretching factors of the upper and lower crust. The results suggest that the whole crustal thickness decreases seaward while the whole crustal stretching factor increases from shelf to slope. The Moho upwells highest beneath where the crust is thinned most. The value of the whole crustal stretching factor ranges from 1.5 to 6. Two areas were thinned intensely: the center of Yinggehai Basin, and the Baiyun sag in the Pearl River Mouth Basin. The calculation of the upper and lower crustal stretching factors from DSP1530 in Baiyun sag shows that the original crust of Baiyun sag should be thinned before deformation. Its pre-Cenozoic evolution as well as tectonic position during Cenozoic might be responsible for that.展开更多
Shish crystals are crucial to achieving high performance low-dimensional ultra-high molecular weight polyethylene(UHMWPE)products.Typically,high stretch and shear flow fields are necessary for the formation of shish c...Shish crystals are crucial to achieving high performance low-dimensional ultra-high molecular weight polyethylene(UHMWPE)products.Typically,high stretch and shear flow fields are necessary for the formation of shish crystals.In this study,UHMWPE gel films with reserved shish crystals were prepared by gel molding,the structural evolution and properties of UHMWPE films stretched at temperatu res of 100,110,120and 130℃were investigated by in situ small-angle X-ray scattering(SAXS)/ultra-small-angle X-ray scattering(USAXS)/wide-angle X-ray diffraction(WAXD)measu rements as well as scanning electron microscopy(SEM)and differential scanning calorimetry(DSC)measurements.Our findings showed that the reserved shish crystals can facilitate the formation and structural evolution of shish-kebab crystals during the hot stretching.Additionally,the reserved shish crystals promote the structu ral evolution of UHMWPE films to a greater extent when stretched at 120 and 130℃,compared to 100 and 110℃,resulting in higher crystallinity,orientation,thermal properties,breaking strength and Young's modulus.Com pared to UHMWPE high-entangled films with reserved shish crystals prepared by compression molding,UHMWPE low-entangled films with reserved shish crystals prepared by gel molding are more effective in inducing the formation and evolution of shish-kebab crystals during the hot stretching,resulting in increased breaking strength and Young's modulus.展开更多
Polyglycolide (PGA) fibers applied as surgical sutures strongly depend on their microstructure. The structural evolution of PGA nascent fibers during single low-temperature stretching and segmented high-temperature st...Polyglycolide (PGA) fibers applied as surgical sutures strongly depend on their microstructure. The structural evolution of PGA nascent fibers during single low-temperature stretching and segmented high-temperature stretching was analyzed based on a combination of in situ WAXD/SAXS and DSC measurements. The results indicated that the hot stretching was conducive to the crystal perfection and the local fragmentation and recrystallization of the lamellar crystals may occur under stress induction. The single low-temperature stretching of PGA nascent fibers could be divided into three stages: the stretching of amorphous regions, stretch-induced crystallization and the stretching of crystalline regions. The elongation at break of the fibers can be substantially increased by adopting a segmented stretching method, and the high-temperature stretching can also significantly increase the crystallinity and orientation. The amorphous orientation peak appearing in the low-temperature stretching was gradually converted to crystallization peak during the heating process, which greatly improved the crystallinity and orientation of the fibers. High-temperature stretching compared with low-temperature stretching was more favorable for crystal perfection and structural evolution, where lamellar crystals underwent stress-induced fragmentation recrystallization to transform to fibrous crystals as the strain increased.展开更多
基金the Key Innovative Program of Chinese Academy of Sciences (Grant No. KZCX3-SW-234-3)the Basic Research Program of China (Grant No. 2007CB411704)the National Natural Science Foundation of China (Grant Nos. 40406012 and 40576027)
文摘To investigate the thinning of the whole crust, and the contribution of the upper versus lower crust to the stretching since Cenozoic, we calculated the stretching factor of the northern margin of South China Sea with data such as whole crustal thickness, depth of Cenozoic sedimentary basement and the horizontal displacement of faults. An isometric line drawing on whole crustal stretching factor is then obtained. Along the seismic Line 1530 in Baiyun sag, we also calculated the stretching factors of the upper and lower crust. The results suggest that the whole crustal thickness decreases seaward while the whole crustal stretching factor increases from shelf to slope. The Moho upwells highest beneath where the crust is thinned most. The value of the whole crustal stretching factor ranges from 1.5 to 6. Two areas were thinned intensely: the center of Yinggehai Basin, and the Baiyun sag in the Pearl River Mouth Basin. The calculation of the upper and lower crustal stretching factors from DSP1530 in Baiyun sag shows that the original crust of Baiyun sag should be thinned before deformation. Its pre-Cenozoic evolution as well as tectonic position during Cenozoic might be responsible for that.
基金financially supported by the National Natural Science Foundation of China(Nos.52173021 and 52373038)Key Research and Development Programme of Zhejiang Province(No.2023C01209)S&T Innovation 2025 Major Special Programme of Ningbo(No.2023Z079)。
文摘Shish crystals are crucial to achieving high performance low-dimensional ultra-high molecular weight polyethylene(UHMWPE)products.Typically,high stretch and shear flow fields are necessary for the formation of shish crystals.In this study,UHMWPE gel films with reserved shish crystals were prepared by gel molding,the structural evolution and properties of UHMWPE films stretched at temperatu res of 100,110,120and 130℃were investigated by in situ small-angle X-ray scattering(SAXS)/ultra-small-angle X-ray scattering(USAXS)/wide-angle X-ray diffraction(WAXD)measu rements as well as scanning electron microscopy(SEM)and differential scanning calorimetry(DSC)measurements.Our findings showed that the reserved shish crystals can facilitate the formation and structural evolution of shish-kebab crystals during the hot stretching.Additionally,the reserved shish crystals promote the structu ral evolution of UHMWPE films to a greater extent when stretched at 120 and 130℃,compared to 100 and 110℃,resulting in higher crystallinity,orientation,thermal properties,breaking strength and Young's modulus.Com pared to UHMWPE high-entangled films with reserved shish crystals prepared by compression molding,UHMWPE low-entangled films with reserved shish crystals prepared by gel molding are more effective in inducing the formation and evolution of shish-kebab crystals during the hot stretching,resulting in increased breaking strength and Young's modulus.
基金financially supported by the National Natural Science Foundation of China (Nos. 51973097 and 52173021)the Open Fund of State Key Laboratory of Biobased Fiber Manufacturing Technology (No. SKL202207)
文摘Polyglycolide (PGA) fibers applied as surgical sutures strongly depend on their microstructure. The structural evolution of PGA nascent fibers during single low-temperature stretching and segmented high-temperature stretching was analyzed based on a combination of in situ WAXD/SAXS and DSC measurements. The results indicated that the hot stretching was conducive to the crystal perfection and the local fragmentation and recrystallization of the lamellar crystals may occur under stress induction. The single low-temperature stretching of PGA nascent fibers could be divided into three stages: the stretching of amorphous regions, stretch-induced crystallization and the stretching of crystalline regions. The elongation at break of the fibers can be substantially increased by adopting a segmented stretching method, and the high-temperature stretching can also significantly increase the crystallinity and orientation. The amorphous orientation peak appearing in the low-temperature stretching was gradually converted to crystallization peak during the heating process, which greatly improved the crystallinity and orientation of the fibers. High-temperature stretching compared with low-temperature stretching was more favorable for crystal perfection and structural evolution, where lamellar crystals underwent stress-induced fragmentation recrystallization to transform to fibrous crystals as the strain increased.
