Key Engineering Materials Vol. 561

Abstract: This article by groups of comparison, analyzes the impact of he content, the mesh size and the kinds of Rubber Powder to Modified asphalt properties. Experiments concluded that, the content of rubber powder has the most impact to rubber powder modifying asphalt properties, and when the content in 10%～20% has a optimal value; the mesh size is not the thinner the better; ordinary rubber powder has a high performance-price ratio.

Abstract: In this paper, we conduct a comparative experiment of the low-temperature single step mixing and multi-stage process mixing with low temperature single process mixing experiment platform. The experimental results show that the low-temperature single step mixing, compared with the traditional multi-stage process mixing, can save energy of about 13.3% and improve production efficiency of about 200%. The performance of final mixing has a significant increase in Mooney viscosity, the carbon black dispersion, and the physical and mechanical properties of the vulcanized rubber.

Abstract: Studying the deformation and fracture properties of soft materials can not only provide insight into the physical mechanisms underlying their superior properties and functions but also benefit the design and fabrication of rubberlike materials. In this paper, an application of the experimental digital moire method to determine the damage zone around crack tip for rubberlike material is presented. The measurement principles and the basic procedures of the method are explained in detail. The in-plane defomation distributions of crack tip fields under Mode I fracture condition are measured. In addition, the deformation of crack tip fields in the damage zones is also analyzed using the sector division mode. Finally, an analysis of the damage zone is proposed to describe crack-tip fields in rubber-like materials with large deformation.

Abstract: Introducing ionic liquid [n-C16mim][BF4] as a new structure-controlled additive, Polysulfone (PSf) membranes were prepared by the wet-phase-inversion using [n-C16mim][BF4] into the casting solution (PSf/NMP). The scanning electron microscope and the atomic force microscopy were utilized to visualize the cross-sections of the membranes to gain more better understanding the structure-controlled ability of [n-C16mim][BF4] and surface morphologies of the membrane. The results indicate that the structures of the membranes were typical bilayer asymmetric finger-pores structure. [n-C16mim][BF4] has stronger ability of the pore-forming. Especially, at the 4:76 ratio of [n-C16mim][BF4]/NMP in the polymer solution ,the membrane has the asymmetric structure and good separation properties of the solution flux. The PSf membrane has the 0.45~0.65μm dimpling close to surface layer, and the retention rate and solution flux of the prepared membrane are 95.2% and 137.5 L•h-1•m-2. Meanwhile, [n-C16mim][BF4] partially retained in the prepared Polysulfone membrane reduced the contact angles of Polysulfone membranes, improving the hydrophilic properties of the membranes.

Abstract: The overall thermal properties of particle reinforced composites are of primary importance for practical applications. Effect of random spatial distribution of sphere particles on the thermal conductivity of composites was numerically studied by ANSYS Workbench Steady-State Thermal analysis module. MATLAB procedure is used to achieve random distribution of particles in composites and to generate a representative volume element (RVE) model. The simulation results indicate that, at the same volume fraction, the random distribution has higher thermal conductivity than the uniform distribution; effect of particles’ spatial distribution on thermal conductivity is greater than volume fraction especially when the volume fraction is between 15% and 35%.

Abstract: In this paper, an experimental mixing equipment has been developed for producing low density material with a high volume filling rate of phenolic hollow microsphere. The experiments with the equipment aim to explore the feasibility of this equipment for industrial production and to optimize the process. Experiments have been made to evaluate the influence of the filling ratio and the mixing rotor movement on the mixing effect. The results show that when the volume filling ratio of the material to the mixing barrel is about 40% the mixing effect is the best. But with mixing time increasing, the broken ratio of hollow microsphere will increase too. To solve this problem, some changes on the rotor movement have been made. The results show that the broken ratio increasing rate becomes lower and the density becomes more uniform. These indicate that the broken ratio can be well controlled by a suitable production process.

Abstract: Injection molded part with micro structures is extensively used as a heatsink, which will provide bright prospects for application. In this present study, analytical models with micro pins, micro holes and micro grooves were specially designed and built. Molding quality and transient heat transfer performance of these parts were investigated via the finite element methods. As research objective, warpage and residual thermal stress of each target under identical molding conditions was compared to evaluate the product quality, and heat dissipation performance of micro structures was applied to assess the applicability of plastic products used as heatsinks. Study results revealed that the part with micro grooves had better molding quality and heat dissipation effectiveness than others.

Abstract: In order to improve the thermal conductivities of composites, AlN are used as thermal conductive fillers of EPDM rubber. The contact angle and surface free energy of AlN and modified AlN are studied. The influence filler amount and the surface treatment of AlN which coated by phenol formaldehyde resin (PF), on the thermal conductivities and mechanical properties of composites material are also investigated. The results show that the surface free energy of modified AlN is lower than unmodified, so the modified AlN are easier dispersion in the matrix. Through the TGA analysis, it can give a quantitative analysis of the surface coating thickness. With the increase of the filler, the thermal conductivities of composites are all on the rise, while the mechanical properties decreased in different degree. The modified AlN have active impacts on the thermal conductivities and harmful to mechanical properties of the filled EPDM rubber.

Abstract: Based on fiber length, fiber orientation distribution and fraction volume, the Halpin-Tsai’ elasticity modulus prediction equation were modified and the elasticity modulus of SGF/TPU composites was experimentally studied. The relationship between the structure and elasticity modulus of SGF/TPU composites was discussed. Results showed that the elasticity modulus of GF-TPU composite rapidly increased as the increasing of fiber volume fraction () and the increasing of the fiber length at the range of 0%-20%. The modified prediction equation of the elasticity modulus fits the test result quite well.

Abstract: Eight kinds of carbon black filled natural rubber composites were prepared, and thermal conductivity was studied. Acetylene black contributes much to the thermal conductivity of rubber, and tiny loading results in considerable improvement. The conductive carbon black 40B2 is advantageous for the improvement in thermal conductivity of rubber when its loading reaches middle level, and at its middle level, also tiny loading results in much improvement. Most kinds of carbon black for rubber application filled rubber composites have good properties except for N134 and N660, especially the poor contribution of N660. Additionally, in the case of carbon black filled rubber composites, addition of filler may not necessarily benefit the thermal conductivity when filler loading is not much.