Nanometer materials include roughly nanoparticle,nanotube, nanowire, nanofiber, nanofilm and nanoblock, among which nanofiber is defined as material with nanometer-sized diameter and longer than 1 micron in length. Th...Nanometer materials include roughly nanoparticle,nanotube, nanowire, nanofiber, nanofilm and nanoblock, among which nanofiber is defined as material with nanometer-sized diameter and longer than 1 micron in length. The research development of polymer nanofibers, including manufacture methods and properties of some polymer nanofibers as well as their potential applications is reviewed.展开更多
Poly (acrylonitrile-methyl acrylate) copolymer was synthesized by water depositing polymerization and has a typical feed ratio of 85/15. And then 1-3 wt% lauryl alcohol maleic anhydride (LAM) was adopted as stabilizer...Poly (acrylonitrile-methyl acrylate) copolymer was synthesized by water depositing polymerization and has a typical feed ratio of 85/15. And then 1-3 wt% lauryl alcohol maleic anhydride (LAM) was adopted as stabilizer to mix with the acrylonitrile based copolymer. The mixtures were characterized by using Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (1H NMR), Gel Permeation Chromatography (GPC), Differential Scanning Calorimetry (DSC), optic microscope and Ubbelohde viscosimetryr etc. The melting point (Tm) and glass transition temperature (Tg) of the 85/15 AN/MA copolymer mixed with LAM all decrease with the increase of stabilizer content. The lowest Tg and Tm were 116.1℃ and 209.1℃ respectively at the heating rate of 100℃/min when the content of LAM is 2 wt%. The 85/15 AN/MA copolymer mixed with 1-3 wt% LAM possess good thermal stability up to 30 min at 220℃.展开更多
The finite element method(FEM)is used for simulation of the tube piercing process in Mannesmann mill.The numerical model is described with taking into consideration thermal phenomena in metal during forming. The simul...The finite element method(FEM)is used for simulation of the tube piercing process in Mannesmann mill.The numerical model is described with taking into consideration thermal phenomena in metal during forming. The simulated results visualize dynamic distributions of mean stresses,temperature,velocity and shear stresses, especially inside the workpiece.On the basis of the basic parameters,the phenomenon in the piercing process is analyzed.The model is verified by comparing the values of calculated force parameters of the piercing process and those measured in laboratory conditions.展开更多
Based on test data from the hot forge experiments on Gleeble 1500, a Kumar type constitutive equation for 33Mn2V steel is established. Applying this constitutive equation in commercial FEM software of MSC/SuperForm 20...Based on test data from the hot forge experiments on Gleeble 1500, a Kumar type constitutive equation for 33Mn2V steel is established. Applying this constitutive equation in commercial FEM software of MSC/SuperForm 2005, the piercing process of 33Mn2V steel in Mannesmann mill is then simulated. The modeling results visualized the dynamic evolution of equivalent stress, especially inside the workpieee. It is shown that the non-uniform distribu- tion of stress on the internal and external surface of the workpiece is a distinct characteristic of processing tube pierc- ing. The numerical model was verified by comparing the values of calculated force parameters of the piercing process with those measured in laboratory eonditions. And it shows that the Kumar-type constitutive relationship meets the practical needs.展开更多
文摘Nanometer materials include roughly nanoparticle,nanotube, nanowire, nanofiber, nanofilm and nanoblock, among which nanofiber is defined as material with nanometer-sized diameter and longer than 1 micron in length. The research development of polymer nanofibers, including manufacture methods and properties of some polymer nanofibers as well as their potential applications is reviewed.
基金Supported by National Natural Science Foundation of China (No.50573058)Specialized Research Found for the Doctoral Programof Higher Education (No.20050058004)
文摘Poly (acrylonitrile-methyl acrylate) copolymer was synthesized by water depositing polymerization and has a typical feed ratio of 85/15. And then 1-3 wt% lauryl alcohol maleic anhydride (LAM) was adopted as stabilizer to mix with the acrylonitrile based copolymer. The mixtures were characterized by using Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (1H NMR), Gel Permeation Chromatography (GPC), Differential Scanning Calorimetry (DSC), optic microscope and Ubbelohde viscosimetryr etc. The melting point (Tm) and glass transition temperature (Tg) of the 85/15 AN/MA copolymer mixed with LAM all decrease with the increase of stabilizer content. The lowest Tg and Tm were 116.1℃ and 209.1℃ respectively at the heating rate of 100℃/min when the content of LAM is 2 wt%. The 85/15 AN/MA copolymer mixed with 1-3 wt% LAM possess good thermal stability up to 30 min at 220℃.
基金the Tianjin Natural Science Foundation (Nos.06YFJMJC02200 and 11JCZDJC22600)Wuxi Steel Tube Factory for its financial support
文摘The finite element method(FEM)is used for simulation of the tube piercing process in Mannesmann mill.The numerical model is described with taking into consideration thermal phenomena in metal during forming. The simulated results visualize dynamic distributions of mean stresses,temperature,velocity and shear stresses, especially inside the workpiece.On the basis of the basic parameters,the phenomenon in the piercing process is analyzed.The model is verified by comparing the values of calculated force parameters of the piercing process and those measured in laboratory conditions.
基金Item Sponsored by Tianjin Natural Science Foundation of China(06YFJ MJC02200,11JCZDJC22600)
文摘Based on test data from the hot forge experiments on Gleeble 1500, a Kumar type constitutive equation for 33Mn2V steel is established. Applying this constitutive equation in commercial FEM software of MSC/SuperForm 2005, the piercing process of 33Mn2V steel in Mannesmann mill is then simulated. The modeling results visualized the dynamic evolution of equivalent stress, especially inside the workpieee. It is shown that the non-uniform distribu- tion of stress on the internal and external surface of the workpiece is a distinct characteristic of processing tube pierc- ing. The numerical model was verified by comparing the values of calculated force parameters of the piercing process with those measured in laboratory eonditions. And it shows that the Kumar-type constitutive relationship meets the practical needs.
