| Summary: | 碩士 === 中原大學 === 化學工程研究所 === 96 === In this study, SiOxCyHz/Mixed cellulose esters (MCE) plasma
deposited membranes were fabricated by hexamethyldisiloxane (HMDSO)
plasma enhanced chemical vapor deposition (PECVD) on the MCE,
which has some advantages, e.g., monomer doesn’t have double bond and
deposition layer with good physical and chemical resistances.
The effects of plasma power and deposition time on the deposition
layer pore size and pore numbers of the SiOxCyHz/MCE plasma deposited
membranes were studied. It shows that the substrate temperature
increases with increasing the deposition time. Meanwhile, the
enhancement of ion bombardment and etching effect results the
deposition rate decreases during the plasma deposition process. The
XPS data revealed that the composition of SiO4 of the deposition layer
increased with increasing the plasma power and deposition time.
The positron annihilation spectroscopy (PAS) coupled with a
variable monoenergy slow positron beam was utilized to detect the depth
profile of the pore size and multilayer structure of the plasma deposited
membrane. It was found that the deposition layer (mixtures of HMDSO
species and MCE species) had more hydrocarbon group, resulting in the
deposition layer had a looser structure at the initial period of plasma
deposition. However, the MCE species content of the deposition layer
decreases as the deposition time further increases. The deposition layer
becomes denser. From the PALS, the o-Ps lifetime (τ3 correspond to the
pore size) decreases along the plasma deposition layer growth direction.
These results correspond with the XPS very well.
The plasma deposited membrane was applied for O2/N2 separation.
The O2 permeance decreased and the O2 concentration in the permeate
enhanced when the plasma power and deposition time increased.
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