Papers by Author: Xue Tao He

Abstract: This paper mainly introduces a new method of preparation of microcellular material, this method can be divided into three stages: kettle with saturation pressure, heating foaming, flattening and calendaring. During the process of supercritical CO₂ saturated, different materials need reasonable control parameters such as saturation pressure, saturation temperature and saturated time, and the values of saturation temperature and saturation pressure will directly affect the permeability of supercritical CO₂. During the process of heating foaming, it needs to strictly control the parameters such as foaming temperature and foaming time, because the bubble density and bubble size are closely related to the two parameters. During flattening and calendaring process, it is important to control temperature and speed of roller reasonably to avoid the phenomena of collapse in bubbles. There are no harmful substances emissions using this method to produce ultrathin microcellular material, which can also protect the environment.

Abstract: In this paper, the 3D flow field and dynamic mixing processing in the continuous mixer with new-type rotors have been studied using finite element software package Polyflow. The influences of continuous mixer process conditions on mixing properties were analyzed by numerical simulation. The results show that the dispersion property is mainly affected by the rotational speed of rotors and the viscosity of polymer. Better dispersion property can be gained as and the viscosity increase. However, the distribution property is mainly affected by feed rate, and the distribution efficiency will reduce if feed rate is too fast.

Abstract: As one directly method to produce nanofibers, electrospinning has been studied extensively. However, the buckling phenomenon is not understood completely especially to the process of melt electrospinning. The authors carried out a series of experimental study on this phenomenon with high speed video. This is the first article of the research, in which we defined three stages to the whole spinning process according to the time. The specialties of each stage were list out. The falling process was divided into straight-line movement, spiral swinging, and deposits on the collector three sections. The buckling reasons were provided.

Abstract: As an economical, resultful and direct method, finite element method has been used broadly to simulate tire performance. However, much of the published research shows few detail model or no material constants. It is difficult for readers to judge if the result is reliable. To ensure simulation results are credible, the material constants, simulation model and analysis method must be dependable. In the current work, the three-dimensional radial tire models, finite element models of free and ground-touching tires, were built and showed in detail. The material constants measured from experiments in a tire factory were published. Using the well-known finite element simulation software ANSYS, the current research found some interesting results which will be presented in Part II.

Abstract: Melt electrospinning is a safer, more environmentally friendly and cheaper alternative to solution electrospinning in producing superfine fibers. In this paper, a novel melt electrospinning device was used, which has higher efficiency than conventional equipment. Polypropylene is widely used in many fields and it is difficult to find a suitable solvent for its solution electrospinning at room temperature, so it was chosen in this study. The influences of the electrospinning parameters such as temperature and voltage on the diameter of the spinning fibers have been studied. Temperatures higher than normal processing temperatures were used in present electrospinning system in order to reduce the viscosity of the polymer melt sufficiently. Good quality fibers with smooth surfaces and with diameters mostly smaller than 10 microns were spun successfully. It was found that there was an optimum point for the spinning voltage (70-80KV) and the temperature (230-260°C) to get fine fibers.

Abstract: In this paper, self-designed electrospinning equipment was used to make a series of electrospinning experiments with materials of polypropylene. The influences of the receiver area, the upper plate area, and the overlapping area between the receiver and the upper plate, on the melt spinning electric field, the spinning efficiency, and the fiber diameter, were investigated respectively. The results showed that when the other parameters were kept unchanged, with the increase of the receiver’s diameter, the electric field strength and spinning efficiency increased, and the fiber diameter increased at first and then decreased; the bigger the overlapping area between the receiver and the upper plate, the more stable the vertical spinning path.

Abstract: In order to improve the dispersion homogeneity and stabilization of multi-walled carbon nanotubes (MWNT) in epoxy resin, the effect of different surfactants such as hexadecyl trimethyl ammonium bromide (HTAB), sodium dodecyl sulfate (SDS), oleic acid, Triton X-100 and BYK-9077 on the dispersion of MWNT were investigated. Suspensions of MWNTs/epoxy resin with various surfactants were prepared by ultrasonic agitation. Dispersion homogeneity of MWNT in epoxy resin was evaluated by transmission electron microscopy (TEM), and dispersion stabilization was evaluated by stationary observation. The results show that dispersion properties were not improved by HTAB, while they were improved incoordinately by SDS, oleic acid, Triton X-100 and BYK-9077. Suspensions of MWNTs/epoxy resin with HTAB, SDS, oleic acid and Triton X-100 were all delaminated quickly, it means, dispersion stabilization were not improved by these surfactants. BYK-9077 was the only surfactant which enhanced the dispersion homogeneity and stabilization of MWNTs/epoxy resin significantly. Based on this research, various weight ratios of surfactant BYK-9077 to MWNT were studied. The experimental results show that the dispersion system could reach a balance state when the ratio of surfactant BYK-9077 to MWN was 2.

Abstract: A finite element model of temperature field coupled with electromagnetic field has been established based on induction heating theory including Maxwell’s equations, thermal conductivity differential equation and magnetic vector potential to simulate the induction heating process of barrel of injection molding machine by universal ANSYS software, and to obtain temperature field of the barrel related to time variation. The coupled thermal and electromagnetic field problem taking account of nonlinear materials characteristics related to temperature was discussed. The induction heating process of barrel was analyzed, and the temperature distribution and its variation with time were obtained.