Papers by Keyword: PC

Abstract: Power semiconductor modules are subject to both thermo-mechanical stress and electro-chemical stress during field operation. Usually, those stressors are investigated separately and possible interaction of both degradation mechanisms is neglected. In this work, the effect of combined thermo-mechanical and electro-chemical stress is investigated by means of consecutive H3TRB and PCT testing. One test group had been subjected to power cycling before the H3TRB test was performed, while another test group had been exposed to H3TRB stress before the power cycling test. As a reference, devices without preconditioning were tested in both, H3TRB and power cycling and are also used to compare the H3TRB and power cycling performance of the SiC devices to similar silicon devices. The results show, that the SiC devices feature a significantly better H3TRB performance than comparable silicon devices, but are inferior in terms of power cycling performance. Furthermore, the results for both test groups of the combined tests indicate that the failure modes for the previously stressed devices were the same as for the pristine devices and no impact of either preceding stress on the devices' lifetime could be observed. Therefore, the results of this work suggest no interaction between both stressors, at least not for the devices used for this investigation.

Abstract: Polybutylene terephthalate (PBT) has been proven to be a potential material for modern car bumpers. However, the potential of PBT is limited by its low notched impact strength. The main aim of this study is the improvement in the notched impact strength of PBT by blending with polycarbonate (PC). PBT/PC blend at different ratios (95/5, 90/10, 85/15, 80/20) is investigated in notched Izod impact strength (ASTM D256) and hardness (ASTM D2240). Results are compared to those of neat PBT. It was found that notched Izod impact strength decreased with increasing PC rate in the blend, overall, from 4.35 kJ/m² of neat PBT to 3.37 kJ/m² of 80/20 blend. The microstructure of testing samples was observed through FESEM images taken at fracture surfaces to determine the cause of the decrease. The low interfacial adhesion between PBT and PC phases is believed to be the main reason. However, an increase in notched impact strength was shown, from 4.18 kJ/m² of 95/5 blend to 4,71 kJ/m² of 90/10 blend. This result is presumed to be due to the compatibilizing effect of PBT-PC copolymers formed during the melt blending process. Hardness testing result demonstrates neither significant improvement nor deterioration. It concluded that it is possible to improve the notched impact strength of PBT by blending with PC. The PBT/10% PC blend is a suitable choice for car bumper material since its notch impact strength is higher than neat PBT.

Abstract: Polycarbonate (PC) has the high impact strength, whereas Polymethylmethacrylate (PMMA) possesses the high tensile strength. Both of them have been widely used for optical elements in illumination. This paper aims to investigate mechanical properties including tensile and impact strengths of PMMA/PC blend with 50 percent of PC concentration by injection molding process. Tensile and impact specimens were designed following ASTM, type V and were fabricated by injection molding process. Taguchi technique was employed to figure out the optimal process conditions for maximum tensile and impact strengths. The processing conditions such as melt temperature, mold temperature, packing pressure and cooling time were applied and each factor has three levels. As a results, melt temperature has been found to be the most significant parameter for both tensile and impact strengths and cooling time is the least significant parameter for the mechanical properties.

Abstract: The effect of blending polycarbonate (PC) into polypropylene (PP) matrix polymer on thermal conductivity and crystal structure was studied. The blends consisted of 5% to 35% of PC with 5% compatibilizer (polypropylene-graft-maleic anhydride or PP-g-MA), were compounded using twin-screw extruder and shaped into standard tests samples by compression molding. The thermal conductivity values for PP/PC/PP-g-MA blends were ranging from 0.22 – 0.24 W/m.K. When compared to Hanshin – Shtrikman model, the highest difference in the thermal conductivity values was 28.2% shown in 90/5/5 composition. The deviation was due to the exclusion of factors such as PC particulates’ geometry, size, and dispersion in PP matrix. X-ray Diffraction (XRD) test revealed the blends’ structures comprised of medium-range order domains, referring to imperfect crystals with nanoparticles. The locations of peaks in the XRD spectrum also suggest that the pure PP’s monoclinic alpha crystal appeared in all PP/PC/PP-g-MA blends and there was no other crystal obtained in the blends. From the result, the discovered traits of crystal structure displayed influence on the thermal conductivity of the blends. At the same time, reactive compatibilization was suspected to take place at the interface of PP and PC phases when PP-g-MA was introduced.

Abstract: In this research, the bullet-collision test was done in the different velocity. The influence of its velocity on the deformation shape after collision was discussed by comparison with experiment and simulation. The velocity of the bullet was chosen in several kinds of speed ranges at 80m/s-250m/s. The angle of incidence with the collision object is 90 degree (head-on collision). The deformation shape was measured by 3D measurement instrument and reconstructed with 3D-CAD based on the 3D digital data. The deformation mark of the polycarbonate plate and the penetration shape of acrylic plastic plate caused by the bullet's collision with the object were examined. In addition, the collision simulation of the bullet was done by using FE analysis code “LS-DYNA”, and these analytical results were compared with the 3D digital data which is the experimental results.

Abstract: The degradation of polycarbonate (PC) food contact materials was studied based on analysis with GC-MS, FTIR, UV-Vis and TG techniques. It was evident that the processing temperature of the materials significantly enhanced the release of bisphenol A, an endocrine disruptor. Investigation of the redshift of UV band also revealed that high temperatures accelerated the aging degradation of PC.

Abstract: Discussed the structure feature, working principle, communication protocol and design of hardware and software of the intelligent measurement and control device based on CAN bus in this paper.

Abstract: Environmental data transferring method based on cell network is featured with good signal coverage, reliability and without network development, therefore, this method has a large application value and prospect. In order to satisfy the demand of long distance, wirelessly environmental parameters sensing, an environmental parameters sensing system based on SMS (Short Message Service) module is developed. The system can measure environmental parameters, and send them by SMS. And also, this system can connect with PC (Personal Computer) as a remote environmental parameters acquiring terminal. Experiment results show that, the environmental parameters sensing system fulfill sensing environmental parameters and sending by SMS successfully.

Abstract: The stable operation of the chain magazine which is important functional parts of the machining centers affects the processing efficiency directly, requiring test bench and related experiments in progress for the chain magazine performance parameters. We design the hardware and software and complete PLC chain magazine test bench based on the control and experimental testing requirements in the analysis of specific institutions and chain magazine movement principle. PLC is the core of the test bench which can achieve the operation of the magazine and the control automatic tool changer. The PLC program according to the experimental requirements can control tool magazine and automatic tool changer different motion process for related test. PC can achieve magazine movement simulation, monitoring the process of the tool changing, as well as recording and analysis of test data. The Anti-interference cabinet of the test bench ensure the stable operation of control system. The tests proved that PLC-based test bench able to meets the test requirements and complete the default action for a series of related tests with simple control, stable operation and scalability.

Abstract: In order to greenhouse plants for automatic irrigation operation, was designed based on the soil moisture monitoring system of RS 485 bus system, the oscillation frequency of the clock oscillation circuit, and a main chip count, frequency signal PC software will be the main chip records show, form curve, thus providing the basis of the data for the automatic irrigation, experimentally tested for a long time, the system performance is stable and reliable.