Correlating the synthesis protocol and properties of polyimide film for Co2 removal
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Date
2018-06
Authors
Yiauw, Diing Ye
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Abstract
Polyimide membrane has a wide variety of applications, especially in natural gas
industry for removing CO2. Although polyimide membrane has been widely studied and
used in the industry, the influence of its synthesis protocol on the properties of polyimide
film that are in favor of CO2 removal is still roughly understood. Hence, polyimides with
different monomer combinations were synthesized via both thermal imidization and also
chemical imidization in order to discover its impact on the properties of the polyimide
film that were important for CO2 removal. The results showed that the final polyimide
molecular weight was affected by the imidization methods, which the conditions offered
by each method played a major role in the growth of polyimide chain. The polyimide
chain length then contributed to the membrane density, although it was also governed by
other factors such as monomer structure and intermolecular interactions. Furthermore,
the type of imidization also governed the intermolecular packing, which was found to be
an critical factor that determined the membrane free fractional volume (FFV). The
permeability and also selectivity were strongly dependent on FFV, which it served as the
characteristic that allowed the tradeoff between the membrane selectivity and permeability.
In addition, cross-linking the polyimide membrane via furnace treatment was also one of
the dominant attributes in deciding the membrane FFV. It was concluded that properties
of polyimides, their membrane formation, and hence gas separation performance were
able to be controlled and improved by their synthesis protocol.