The ridge-cross rib microstructures of Carystoides escalantei butterfly wing scales have been reproduced by 2D and 3D models via the ANSYS software,and the structural analyses under tensile and bending deformation,as ...The ridge-cross rib microstructures of Carystoides escalantei butterfly wing scales have been reproduced by 2D and 3D models via the ANSYS software,and the structural analyses under tensile and bending deformation,as well as the relative failure analyses are performed for those models.It has been found that the curved model in which the ridges acted as triangular prisms while the cross-ribs acted as bend cuboids could simulate the real scale configuration more accurately.Besides,it also shows much more even stress distribution under deformation and better mechanical properties than the rectangular one,in which both ridges and cross-ribs are modeled as regular cuboids.展开更多
Poly[2, 6-diimidazo (4,5-b:4’,5’-e) pyridinylene-1,4(2,5-dihydroxy) phenylen] (PIPD) was synthesized and the obtained PIPD/ PPA dope was directly spun into fibers via a dry-jet wet-spinning process for the first tim...Poly[2, 6-diimidazo (4,5-b:4’,5’-e) pyridinylene-1,4(2,5-dihydroxy) phenylen] (PIPD) was synthesized and the obtained PIPD/ PPA dope was directly spun into fibers via a dry-jet wet-spinning process for the first time. The obtained polymers were mainly characterized by ATR-FTIR and dynamic contact angle analysis. FTIR spectrum of the PIPD fibers indicates that the product was consistent with the target product. The contact angle measurements show that the wetting process of water on PIPD fibers is apparently faster than that on PBO fibers. The axial compression bending test indicates that PIPD fibers showed larger compressive strength compared with that of PBO fibers under the same axial compressive load. Meanwhile, the TGA test results indicate that the PIPD fibers have excellent thermal stability.展开更多
A series of novel fluorinated benzoxazole polymers (6FPBO's) with high thermal stability and low dielectric constant were synthesized by copolymerization of 1,3-diamino-4, 6-dihydroxybenzene dihy-drochloride (DAR)...A series of novel fluorinated benzoxazole polymers (6FPBO's) with high thermal stability and low dielectric constant were synthesized by copolymerization of 1,3-diamino-4, 6-dihydroxybenzene dihy-drochloride (DAR), 1,4-benzenedicarboxylic acid (PTA) and various amount of 4'4- (hexafluoroisopro-pylidene) bis (benzoic acid) (BIS-B-AF) in the medium of polyphosphoric acid (PPA). 6FPBO fibers were then obtained via dry-jet wet-spinning technique and characterized by means of Fourier transform infrared (FTIR) spectra, thermogravimetric analysis (TGA), single fiber tensile testing machine and scanning electron microscopy (SEM). FTIR spectrum of 6FPBO fibers indicated that the fluorine groups had been incorporated into PBO molecular chains successfully. TGA curves revealed that 6FPBO fibers possessed high thermal stability just as pure PBO fibers. Moreover, dielectric constant spectrum of 6FPBO exhibited that the polymers had low dielectric constant, especially in the range of high- frequency.展开更多
文摘The ridge-cross rib microstructures of Carystoides escalantei butterfly wing scales have been reproduced by 2D and 3D models via the ANSYS software,and the structural analyses under tensile and bending deformation,as well as the relative failure analyses are performed for those models.It has been found that the curved model in which the ridges acted as triangular prisms while the cross-ribs acted as bend cuboids could simulate the real scale configuration more accurately.Besides,it also shows much more even stress distribution under deformation and better mechanical properties than the rectangular one,in which both ridges and cross-ribs are modeled as regular cuboids.
基金supported by National Natural Science Foundation of China (50673017)Program for Outstanding Academic Leaders of Shanghai and Program of Introducing Talents of Discipline to Universities (111-2-04)
文摘Poly[2, 6-diimidazo (4,5-b:4’,5’-e) pyridinylene-1,4(2,5-dihydroxy) phenylen] (PIPD) was synthesized and the obtained PIPD/ PPA dope was directly spun into fibers via a dry-jet wet-spinning process for the first time. The obtained polymers were mainly characterized by ATR-FTIR and dynamic contact angle analysis. FTIR spectrum of the PIPD fibers indicates that the product was consistent with the target product. The contact angle measurements show that the wetting process of water on PIPD fibers is apparently faster than that on PBO fibers. The axial compression bending test indicates that PIPD fibers showed larger compressive strength compared with that of PBO fibers under the same axial compressive load. Meanwhile, the TGA test results indicate that the PIPD fibers have excellent thermal stability.
基金Supported by the National Natural Science Foundation of China (Grant No. 50673017)the Program for New Century Excellent Talents in University (Grant No. NCEN-04-0417)
文摘A series of novel fluorinated benzoxazole polymers (6FPBO's) with high thermal stability and low dielectric constant were synthesized by copolymerization of 1,3-diamino-4, 6-dihydroxybenzene dihy-drochloride (DAR), 1,4-benzenedicarboxylic acid (PTA) and various amount of 4'4- (hexafluoroisopro-pylidene) bis (benzoic acid) (BIS-B-AF) in the medium of polyphosphoric acid (PPA). 6FPBO fibers were then obtained via dry-jet wet-spinning technique and characterized by means of Fourier transform infrared (FTIR) spectra, thermogravimetric analysis (TGA), single fiber tensile testing machine and scanning electron microscopy (SEM). FTIR spectrum of 6FPBO fibers indicated that the fluorine groups had been incorporated into PBO molecular chains successfully. TGA curves revealed that 6FPBO fibers possessed high thermal stability just as pure PBO fibers. Moreover, dielectric constant spectrum of 6FPBO exhibited that the polymers had low dielectric constant, especially in the range of high- frequency.
