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A series of novel polydimethylsiloxane (PDMS) composites were prepared using octa[(trimethoxysilyl)ethyl]‐POSS (OPS) as cross‐linker and fumed silica as reinforcing filler. The cross‐linked networks, morphologies, thermal and mechanical properties of these novel PDMS composites were examined by attenuated total reflection infrared spectroscopy and the extraction/swelling experiment, scanning electron microscope, thermogravimetric analysis, and universal tensile testing machine, respectively. It was found that both the resistance to thermal degradation and mechanical properties of the novel PDMS composites were improved greatly by adding fumed silica. The prominent improvements in resistance to thermal degradation and mechanical properties of novel PDMS composites were likely attributed to the enhanced interaction of PDMS chains and aggregated particles resulted from synergistic effect between POSS and fumed silica. Meanwhile, we also found that the resistance to thermal degradation of the PDMS composites was lowered slightly with the further increment in loading fumed silica, but their mechanical properties were enhanced. The slight decrease in trend of the resistance to thermal degradation of the novel PDMS composites was likely ascribed to the increasing amount of hydroxyl groups resulting from fumed silica. And the improving mechanical properties were mainly attributed to the increasing interaction of PDMS chains and aggregated particles originated from synergistic effect between POSS and fumed silica. POLYM. COMPOS., 34:1041–1050, 2013. © 2013 Society of Plastics Engineers

Electrochemical mill-grinding (ECMG) is an ideal technical means to achieve an efficient and precise machining of titanium alloy monolithic structural parts. In the rough ECMG process, the selection of a reasonable cutting depth can improve the machining efficiency of the rough machining. Adopting a reasonable cathode tool structure can achieve a higher precision in the formation of the rough surface, reduce the finishing allowance and tool wear of subsequent finishing. With this aim, the present research proposed a cathode tool with a reasonable structure. Simulation results showed that the designed cathode tool presented a good uniformity of the flow field in the machining gap, which resulted in a higher precision in the formation of the rough surface. For experimental validation, a larger cutting depth and a designed cathode tool was employed to carry out the rough and finish machining experiments on a Ti6Al4V titanium alloy. The experimental results show that a good flatness of the sidewall of the rough-machining groove was obtained by this scheme. Furthermore, the machining surface exhibited no flow marks, and rough machining accounted for 92.37% of total removal. Moreover, measurement of the micro-morphology, roughness and elemental composition of the machined surface, and the effects of different machining parameters on the surface quality of titanium alloys, were studied.

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Electroforming has been applied in the fabrication of a mold. However, its lower microhardness has prevented its wider usage in general plastics and optical mold making. In this paper, CeO 2 nanoparticles is first added to the bath to improve the microhardness of the electroformed microprism mold. Compared with microprism pure nickel mold, the microhardness and the wear resistance of the microprism Ni-CeO 2 nanocomposite mold were significantly improved. The maximum microhardness of 530 HV was observed in the nanocomposite deposits obtained at the current density of 1 Adm -2 , and the microhardness of pure nickel is approximately 291 HV. Finally, a microprism Ni-CeO 2 nanocomposite mold was successfully electroformed.