Nanofibers of titania and composite nanofibers of titania and multiwall carbon nanotubes were synthesized by electrospinning using a sol-gel process combined with activated carbon nanotubes. The relationships of treatment temperature, carbon nanotube content on the crystal phase, fiber morphology, and electric properties are reported. It is found that the rutile phase becomes more prominent at low heat treatment temperatures with an increase of carbon content in nanofibers, be it for higher amount of carbon due to reducing atmosphere or due to an increase in MWCNT. Atmospheric control and lower heat treatment temperatures enable crystalline nanocomposite fibers of anatase where the level of rutile is below the detection limit of XRD or Raman spectroscopy. This work provides a new path to fabricate electrospun TiO2/MWCNT nanocomposite nanofibers with limited C-induced rutile phase. 相似文献
Summary: Silk fibroin cast film was prepared using a ternary solvent system of CaCl2/CH3CH2OH/H2O (1/2/8 in mole ratio). A drying temperature at casting influenced crystal structure of fibroin. When a drying temperature was set lower than 9 °C, the cast film became amorphous. When a drying temperature was set higher than 40 °C, a fibroin film of silk‐II structure was obtained. In order to produce a fibroin film of silk‐I structure, a preferable temperature range was from 20 to 26 °C. The crystal transformation from random coil structure into silk‐I could be made through exposure of an amorphous film to water vapor. As for the crystal transformation from silk‐I into silk‐II, the treatment with a glycerin solution was effective. In the course of the treatment a film showed self‐thinning and self‐expanding. The expansion ratio exceeded 40% at maximum. The film produced accompanying self‐expansion was ductile in nature.
The apparent self‐expansion percentage as a function of initial thickness of the film. The ductility of the film was classified into four stages from the observation of recovery behavior after folding: ?, very soft; ?, soft; ?, middle; ?, hard (see Figure 5 ). 相似文献
The coupling transformation of n-hexane and methanol over HZSM-5 has been investigated with a pulse-reaction system. In the temperature range of 400–500 °C,
kinetic data was collected and reaction order was determined. Compared with the pure n-hexane cracking, the increased rate constant and the lowered apparent activation energy clearly demonstrate an improvement
of n-hexane activation using methanol as co-reactant and an increased contribution of faster bimolecular mechanism to the n-hexane transformation due to methanol introduction. Similarly, the results of coupling transformation performed over HZSM-5
with different Al content further confirm the transition between reaction mechanisms of n-hexane on account of the introduction of methanol. Moreover, the further investigation suggests that the enhancement of n-hexane activation and the change of reaction mechanism are attributed to the presence of intermediate species evolved from
methanol. Thus, a proposed reaction pathway of n-hexane activation with methanol as co-reactant was put forward. 相似文献