Key Engineering Materials Vol. 501

Abstract: A new concept of microinjection molding module was designed and presented. The module was designed as a multi microinjection module, which is matched with a vertical injection molding machine (IMM) and can be applied to usual IMMs. A planetary gear pump was integrated in this module to complete the multi microinjection molding(MμIMM)。The module is fixed between the stationary platen and the mold of IMM. The plasticizing unit of the IMM provides the melt and initial pressure for the multi microinjection molding module. With this module, a usual IMM could be upgraded to a precise microinjection machine and has the capability of precise metering for the microinjection molding.

Abstract: Filling-to-packing switchover control during injection molding plays a crucial role in ensuring the quality of the molded parts. In this study, a filling-to-packing switchover mode based on cavity pressure was presented, and it was compared with other two switchover modes by injection time and screw position. The objective of this study was to validate the accuracy of the switchover mode based on cavity pressure, and examine its consistency. Weight of the molded parts served as the main measure to probe the process capabilities. In this study, the change in mold temperature was monitored; variation of mold temperature affecting the process was examined. The results of the verification experiments revealed that the switchover mode based on cavity pressure could yield a better part quality and consistent part weight compared with the other two traditional switchover modes. It was proved that the switchover mode by cavity pressure can be used to improve the precision of the injection molding. However, a suitable switchover pressure must be used for achieving such high process capability, and the position to get the pressure signal and mold temperature should also be considered.

Abstract: In this present work attempts have been made to study the difference between microwave heating and conventional thermal heating in curing the epoxy-amine system of di-glycidyl ether bisphenol-A(DGEBA) with the curing agent of 4,4′Diamino diphenyl methane(DDM). Curing behaviors and mechanical properties of the system were studied through a number of experiments. Differential scanning calorimetry (DSC) technique was implemented to measure the glass transition temperature and kinetic parameters, and fourier transform infrared spectroscopy(FT-IR) was used to analyse the cure reaction mechanism of the resin system. Finally, microstructure of microwave-cured materials was also studied by using a scanning electron microscope(SEM) in order to analyze the morphology of cured specimens.

Abstract: In this study, the drum washer’s dynamic model has been conducted using Four-terminal parameter method. Firstly, the basic principles and advantages of the four-terminal parameters has been explained, and we have analyzed the vibration mechanism of the drum washer. Secondly, the drum washer was simplified ,and we extracted its dynamic model. Thirdly, we solve each of its components by using the four-terminal parameter method,and according to the connection between the components, determine each component and the system’s four-terminal parameters .Then, deduce the system’s matrix equations,get the complex steady-state response and steady-state response under sinusoidal excitation of the system. Last, input the drum washer’s actual parameters ,we can see that four-terminal parameter method dynamics model is correct. In a word, it is easy to analyze the vibration of complex systems. This paper is designed to provide theoretical support for the design of the drum washer’s damping device.

Abstract: In order to improve the corrosion resistance and the hardness of the 45 steel, under comparison tests, the electroless Ni-B was prepared on the 45 steel. We made a contrast test to get the optimal formula. The coating under the optimal formula was characterized by Scanning Electron Microscopy(SEM), Energy Dispersive Spectrometer(EDS), metallurgical microscope and salt spray cabinet. The experimental results showed that the electroless Ni-B coating on 45 steel was low boron coating, with high hardness, and the hardness of the coating could catch HV524; the thickness of the coating was 16μm.

Abstract: Rubber injection molding is applied in more and more applications in rubber production process. Design of gating system is the most important in rubber injection mold design. Poor runner design will lead to uneven injection velocity and pressure which affect the size and shape and the quality of the rubber products. This paper first adopted POLYFLOW numerical simulation. Three different inlet flow rates for multi-cavity mold were simulated and analyzed by POLYFLOW software in this paper. Non-equilibrium gating system was further optimized by the calculation method of Balanced Gate Value and numerical simulation. The best inlet flow rate and the best runner size were ultimately obtained. It was proven that Numerical simulation results are of great significance for rubber injection mold design and injection molding processing parameter selection.

Abstract: The alloy of Nylon6/Acrylonitrile-Butadiene-Styrene (ABS), with the ratio of 90/10, was prepared with ABS grafted with the maleic anhydride (ABS-g-MAH), as the compatibilizer. The mechanical tests’ results showed that the impact strength of the alloy with the compatibilizer was improved by about 146%. t can be seen from the scanning electron microscope (SEM) photographs that the compatibility was improved by the addition of ABS-g-MAH. The melting behavior and isothermal crystallization kinetics of Nylon6/ABS/ABS-g-MAH blends were investigated using DSC. The melting behavior was largely affected by the crystallization temperature and the presence of ABS-g-MAH.

Abstract: Dissipative particle dynamics (DPD) is used in this work to simulate the distribution of carmustine (BCNU) molecules in konjac glucomannan (KGM) as potential drug carrier. It is shown from DPD simulation that the aggregated morphology of KGM differs at varying BCNU concentration levels. At 1 mol % of BCNU the phase aggregates as spherical particles, and at 5 mol% of BCNU, some BCNU molecules were partially uncovered by KGM molecules due to high drug concentration. However, even at higher concentration, most of the BCNU molecules are distributed in the inner area of the matrix, indicating that KGM interacts with BCNU well and it is a promising drug carrier for BCNU in water. DPD simulations may provide a powerful tool for designing drug delivery systems.

Abstract: Soy protein has been considered as a kind of natural polymer and an ecological material that was widely used in many fields such as food industry. In this paper, the soy protein isolate (SPI) was modified by glutaric dialdehyde and characterized by IR spectra, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The modified soy protein isolate as reinforcing filler partly replaced some carbon black was used to prepare the SPI/rubber composites. Based on the mechanical and dynamic tests of their vulcanizates, the results showed that when a small amount of modified SPI (8~10phr) as reinforcement agent was used, the mechanical properties were improved. Moreover, the changes of their lgE’ and tanδ occurred.

Abstract: Foaming moulding process, cellular structure and dielectric property of polyimide (PI) foam which has been prepared by esterification method were discussed. Research results showed that the cell of prepared PI foam was well-distributed and its pore volume and porosity were bigger by microwave heating when methanol was used as the foaming agent and its content in the polyester ammonium salt (PEAS) precursor powder was 13-15%; meanwhile, the dielectric constant and loss factor of PI foam were lower.