A micro-layer model is proposed to account for the lubrication effect of liquid layer near collisions of immersed particles at moderate particle Reynolds number.This new model is to allow determination of the pressure...A micro-layer model is proposed to account for the lubrication effect of liquid layer near collisions of immersed particles at moderate particle Reynolds number.This new model is to allow determination of the pressure profile within the micro-layer including the fluid inertia and viscosity.Then a correction based on the micro-layer model is applied to unsteady 3-D direct simulation of a particle approaching another one.The simulation is based on a modified immersed boundary method with direct force scheme.The quantitative agreement between numerical and experimental results validates the model presented in the study.The simulation results show that the fluid is squeezed prior to contact.When a particle approaches a flat wall or another particle,the lubrication force,obtained by integrating the pressure profile over the particle surface,is increased and prevents the particle from approaching.The model predicts that the velocity of approaching particle starts to decrease when separation distance of particles is less than 0.1dp,where dp is the particle diameter.展开更多
Based on the basic operating principal and the technology characteristic of electron beam physical vapor deposition(EBPVD) technique, EBPVD was used to prepare the micro-layer composites. The effect on the substrate p...Based on the basic operating principal and the technology characteristic of electron beam physical vapor deposition(EBPVD) technique, EBPVD was used to prepare the micro-layer composites. The effect on the substrate preheating temperature was taken into accounts and the finite element analysis package ANSYS was used to simulate the internal stress field and the potential displacement changing tendency. The results show that one of the most important quality factors on the judgment of micro-layer composites is the adhesion between the substrate and the deposition layers as well as among the different deposition layers. Besides the existance of temperature gradient through the thickness of layers, the main reason for the internal stress in micro-layer composites is the mismatch of various properties of the layer and the substrate of different thermal expansions and crystal lattice types. With the increase of substrate preheating temperature, the inter-laminar shear stress also takes on a tendency of increase but the axial residual stress decrease.展开更多
The development of crystalline and Meso-phase structure by solid state extrusion from50℃ to 90℃ is studied for PET. The unit cell parameters of stress-induced crystallites inextrudates are determined as a function o...The development of crystalline and Meso-phase structure by solid state extrusion from50℃ to 90℃ is studied for PET. The unit cell parameters of stress-induced crystallites inextrudates are determined as a function of extrusion draw ratio (EDR), and展开更多
The work is dedicated to develop a one-step eco-friendly method to prepare antibacterial polyethylene terephthalate(PET).We report a one-step eco-friendly method to manufacture antibacterial PET via on-line amination ...The work is dedicated to develop a one-step eco-friendly method to prepare antibacterial polyethylene terephthalate(PET).We report a one-step eco-friendly method to manufacture antibacterial PET via on-line amination reaction by melt coextrusion.Beside evenly mixing of poly(hexamethylene guanidine)(PHMG)and PET in the melt coextrusion procedure,the amination reaction also occurred between PHMG and PET under high temperature(230-270℃).The antibacterial ability of composite PET showed obvious PHMG concentration dependence,and antibacterial activity reached more than 99%when PHMG content was 2.5 wt%.Moreover,LIVE/DEAD fluorescence test further confirmed that the composite PET could kill bacteria quickly and efiectively(within 30 min);while negligible cytotoxicity was observed to HSF and HUVEC cells.Onestep eco-friendly fabrication of composite antibacterial PET was accomplished by on-line melt coextrusion.The composite antibacterial PET has potential use in multiple fields to combat with pathogenic including textiles,packaging materials,decoration materials and biomedical devices,etc.展开更多
This paper briefly introduces the characteristics of electron beam physical vapor depo-sition (EBPVD) technique and the whole process of preparing micro--layer compositelaminate. And several major influencing factors ...This paper briefly introduces the characteristics of electron beam physical vapor depo-sition (EBPVD) technique and the whole process of preparing micro--layer compositelaminate. And several major influencing factors are presented and discussed. It wasfound that residual gas pressure should be low enough to guarantee the unobstructedtransporfation of vapor steam and electron beam; the evaporation method and evapo-ration speed are up to the different vapor pressure deficit of compositions of raw mate-rials; and the substrate temperature could have great influence on the microstructureof the micro--layer laminates.展开更多
文摘A micro-layer model is proposed to account for the lubrication effect of liquid layer near collisions of immersed particles at moderate particle Reynolds number.This new model is to allow determination of the pressure profile within the micro-layer including the fluid inertia and viscosity.Then a correction based on the micro-layer model is applied to unsteady 3-D direct simulation of a particle approaching another one.The simulation is based on a modified immersed boundary method with direct force scheme.The quantitative agreement between numerical and experimental results validates the model presented in the study.The simulation results show that the fluid is squeezed prior to contact.When a particle approaches a flat wall or another particle,the lubrication force,obtained by integrating the pressure profile over the particle surface,is increased and prevents the particle from approaching.The model predicts that the velocity of approaching particle starts to decrease when separation distance of particles is less than 0.1dp,where dp is the particle diameter.
基金Project(50304007) supported by the National Natural Science Foundation of China
文摘Based on the basic operating principal and the technology characteristic of electron beam physical vapor deposition(EBPVD) technique, EBPVD was used to prepare the micro-layer composites. The effect on the substrate preheating temperature was taken into accounts and the finite element analysis package ANSYS was used to simulate the internal stress field and the potential displacement changing tendency. The results show that one of the most important quality factors on the judgment of micro-layer composites is the adhesion between the substrate and the deposition layers as well as among the different deposition layers. Besides the existance of temperature gradient through the thickness of layers, the main reason for the internal stress in micro-layer composites is the mismatch of various properties of the layer and the substrate of different thermal expansions and crystal lattice types. With the increase of substrate preheating temperature, the inter-laminar shear stress also takes on a tendency of increase but the axial residual stress decrease.
文摘The development of crystalline and Meso-phase structure by solid state extrusion from50℃ to 90℃ is studied for PET. The unit cell parameters of stress-induced crystallites inextrudates are determined as a function of extrusion draw ratio (EDR), and
基金Funded by the National Natural Science Foundation of China(No.51703169)Key Program of Science and Technology of Jieyang City(No.2019016)Key Research and Development Program of Shandong Province of China(No.2019JZZY010338)。
文摘The work is dedicated to develop a one-step eco-friendly method to prepare antibacterial polyethylene terephthalate(PET).We report a one-step eco-friendly method to manufacture antibacterial PET via on-line amination reaction by melt coextrusion.Beside evenly mixing of poly(hexamethylene guanidine)(PHMG)and PET in the melt coextrusion procedure,the amination reaction also occurred between PHMG and PET under high temperature(230-270℃).The antibacterial ability of composite PET showed obvious PHMG concentration dependence,and antibacterial activity reached more than 99%when PHMG content was 2.5 wt%.Moreover,LIVE/DEAD fluorescence test further confirmed that the composite PET could kill bacteria quickly and efiectively(within 30 min);while negligible cytotoxicity was observed to HSF and HUVEC cells.Onestep eco-friendly fabrication of composite antibacterial PET was accomplished by on-line melt coextrusion.The composite antibacterial PET has potential use in multiple fields to combat with pathogenic including textiles,packaging materials,decoration materials and biomedical devices,etc.
基金This work was supported by the Natural Science Foundation of Heilongjiang Province(No.E01-07)Postdoctoral Science Foundation of China(No.LB0047).
文摘This paper briefly introduces the characteristics of electron beam physical vapor depo-sition (EBPVD) technique and the whole process of preparing micro--layer compositelaminate. And several major influencing factors are presented and discussed. It wasfound that residual gas pressure should be low enough to guarantee the unobstructedtransporfation of vapor steam and electron beam; the evaporation method and evapo-ration speed are up to the different vapor pressure deficit of compositions of raw mate-rials; and the substrate temperature could have great influence on the microstructureof the micro--layer laminates.
