Low-temperature plasma treatment was adopted to graft styrene onto polytetrafluo- roethylene （PTFE） powder, which is widely used in the fabrication of proton exchange membrane （PEM）. The grafted PTFE powder was su...Low-temperature plasma treatment was adopted to graft styrene onto polytetrafluo- roethylene （PTFE） powder, which is widely used in the fabrication of proton exchange membrane （PEM）. The grafted PTFE powder was sulfonated in chlorosulfonic acid and fabricated into a membrane, which was used as inexpensive PEM material for a proton exchange membrane fuel cell （PEMFC）. Fourier transform infrared spectroscopy attenuated total reflection spectroscopy （FTIR-ATR） and X-ray photoelectron spectroscopy （XPS） analysis were used to characterize the structure of the sulfonated PTFE powder. The results showed that all the PTFE powders were successfully grafted by nitrogen plasma and then sulfonated under such experimental conditions. A scanning electron microscopy （SEM） image indicated that the fabricated membrane exhibits flat morphology and homogenous structure. The ion exchange capacity （IEC） of this kind of PEM was also investigated.展开更多
TiO2 filled polytetrafluoroethylene (PTFE) composite were fabricated for microwave circuit applications. PTFE/TiO2 composites were prepared by cold pressing and hot treating. The particle size of TiO2 varied from 5 μ...TiO2 filled polytetrafluoroethylene (PTFE) composite were fabricated for microwave circuit applications. PTFE/TiO2 composites were prepared by cold pressing and hot treating. The particle size of TiO2 varied from 5 μm to 11 μm.TiO2 powders with different sizes were prepared by the solid state ceramic route. The effects of TiO2 particle size on the microstructure, density, moisture absorption, thermal conductivity and microwave dielectric properties of PTFE/TiO2 composites were investigated. The density showed an increasing trend as the TiO2 particle size increased, while the dielectric loss (tanδ) and moisture absorption decreased with the increase of TiO2 particle size. The dielectric constant (εr) and thermal conductivity (λ) decreased up to D50 = 6.5 μm and then sharply increased. Good properties with values of εr = 6.8, tanδ = 0.0012 and λ = 0.533 W?m?1?K?1 were obtained in PTFE/TiO2 composites when the particle size of TiO2 was 11 μm.展开更多
文摘Low-temperature plasma treatment was adopted to graft styrene onto polytetrafluo- roethylene （PTFE） powder, which is widely used in the fabrication of proton exchange membrane （PEM）. The grafted PTFE powder was sulfonated in chlorosulfonic acid and fabricated into a membrane, which was used as inexpensive PEM material for a proton exchange membrane fuel cell （PEMFC）. Fourier transform infrared spectroscopy attenuated total reflection spectroscopy （FTIR-ATR） and X-ray photoelectron spectroscopy （XPS） analysis were used to characterize the structure of the sulfonated PTFE powder. The results showed that all the PTFE powders were successfully grafted by nitrogen plasma and then sulfonated under such experimental conditions. A scanning electron microscopy （SEM） image indicated that the fabricated membrane exhibits flat morphology and homogenous structure. The ion exchange capacity （IEC） of this kind of PEM was also investigated.
文摘TiO2 filled polytetrafluoroethylene (PTFE) composite were fabricated for microwave circuit applications. PTFE/TiO2 composites were prepared by cold pressing and hot treating. The particle size of TiO2 varied from 5 μm to 11 μm.TiO2 powders with different sizes were prepared by the solid state ceramic route. The effects of TiO2 particle size on the microstructure, density, moisture absorption, thermal conductivity and microwave dielectric properties of PTFE/TiO2 composites were investigated. The density showed an increasing trend as the TiO2 particle size increased, while the dielectric loss (tanδ) and moisture absorption decreased with the increase of TiO2 particle size. The dielectric constant (εr) and thermal conductivity (λ) decreased up to D50 = 6.5 μm and then sharply increased. Good properties with values of εr = 6.8, tanδ = 0.0012 and λ = 0.533 W?m?1?K?1 were obtained in PTFE/TiO2 composites when the particle size of TiO2 was 11 μm.
