Ramie fibres were surface treated in order to enhance the interfacial interaction between ramie natural fibres and vinyl resin matrix. The fibres are exposed to three different treatment ways in this paper. The surface topography and binding force influenced by the treatments were characterized by contact angle and mechanical property. Single fibre pull-out tests combined with SEM characterization of the fracture surfaces were used to identify the interfacial strengths and to reveal the mechanisms of failure.
Flax fibres surface were treated by different treatment in order to enhance the interfacial bonding force between flax natural fibres and vinyl resin matrix. The experiment of contact angle and mechanical property were done to characterize the surface topography and bonding force and choose the best modification. What’s more, the morphology behaviour of the flax fibre surface were charact- erized using SEM.
Polymer based composites are widely used in the automobile body panels instead of the steel sheet, due to the requirement of reducing automobile weight. Natural fiber composites were proposed to be used for the car bumper beam. In this paper, the mold filling process of the car bumper beam model for VARTM process was simulated by the software of the RTM-worx. The optimization injection scheme was determined based on the simulation results of the different schemes. It was found that the multiple injection ports would reduce the filling times, and the scheme 6 was the best one for the injection. The filling times of the optimization scheme 6 was 742 s, and two vents at the position A and B would expel the bubbles at the intersectional regions of the resin. Moreover, the optimization scheme could be directly used in the practical production.
Gas-liquid flows driven by rotating rigid objects are numerically studied. The Volume-Of-Fluid (VOF) and Boundary Data Immersion (BDI) methods are employed to treat the gas-liquid and fluid-rigid interfaces, respectively. The basic equations are solved by means of finite difference method using a regular Cartesian mesh. Two types of systems are considered: one is a simple geometry composed of cylindrical disk and container to exhibit the validity of the numerical approach, and the other is a complex geometry including holes and/or caves to clarify the relevance to the two-phase mixing and forcing. Numerical simulations are performed for various angular speeds and compared with the experiments. The simulated results demonstrate the capability in capturing the gas-liquid distribution, the torque on the disk and the velocity distribution obtained by Particle Image Velocimetry (PIV). For the complex system, the torque at low is dependent mainly on irrespective of the presence of the holes/caves, while beyond a certain , the considerable jetting flow structure forms due to the presence of the holes on the disk, and therefore the geometry effect on the torque becomes significant.
Fe3O4 particles were prepared by the co-precipitating method in the presence of polyethylene glycol (PEG). They were characterized by the Transmittance electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectroscope, which indicate the formation of spherical Fe3O4 particles with a wide range of sizes (up to 200 nm in radius) and the polydispersity of particle size below 20%. Furthermore, the magnetic properties of Fe3O4 particles were measured using a vibrating sample magnetometer (VSM), indicating that the particles possess high saturation magnetization at room temperature. These results are attributed that the Fe3O4 particles were directly coated with PEG in a seeded growth Sto¨ber process.
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