The evolution of physicochemical and transport properties of 6FDA-durene toward carbon membranes; from polymer, intermediate to carbon

Lu Shao; Tai Shung Chung; K. P. Pramoda

doi:10.1016/j.micromeso.2005.04.026

The evolution of physicochemical and transport properties of 6FDA-durene toward carbon membranes; from polymer, intermediate to carbon

Lu Shao, Tai Shung Chung^*, K. P. Pramoda

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

94 Scopus citations

Abstract

A high T_g material, which is 6FDA-durene (T_g: 425 °C) polyimide, is applied to study the T_g's effect on the evolution of physicochemical and transport properties of membranes from polymeric, intermediate to carbon stages. T_g greatly affects the configurational organization of membranes during pyrolysis especially at the intermediate stage (400-500 °C) and finally influences the pore size and pore size distribution of carbon membranes, which has been mostly ignored by the previous studies. The physicochemical and transport properties in various membrane stages are thoroughly characterized by TGA-FTIR, FTIR-ATR, XRD, thickness and gas transport tests. It is found that the membranes derived from the high T_g polyimides show a significant increase in chain mobility and physicochemical development in the intermediate stage. Interestingly, the gas permeability with annealing temperature show double peaks for medium-size gases such as O₂, N₂ and CH₄, and single peaks for light gases such as He, H₂ and CO₂. In addition, the ideal selectivity generally shows double minimum values with annealing temperature. These phenomena may arise from the fact that significant physicochemical changes take place around the T_g, while the maximum degradation rate occurs at temperatures 70-100 °C above T_g. As compared with the trade-off line [L.M. Robeson, J. Membr. Sci. 62 (1991) 165], the temperature for membranes derived from the high T_g polyimide to surpass the trade-off line occurs around 450 °C. This temperature is just fall on the intermediate-stage temperature range. The resultant carbon membranes pyrolyzed with 1 °C/min heating rate show better transport performance at low pyrolysis temperatures than those pyrolyzed with 3 °C/ min heating rate. However, when the pyrolysis temperature is elevated to 800 °C, the resultant carbon membranes pyrolyzed by different protocols all show similar and superior performance for gas separation.

Original language	English (US)
Pages (from-to)	59-68
Number of pages	10
Journal	Microporous and Mesoporous Materials
Volume	84
Issue number	1-3
DOIs	https://doi.org/10.1016/j.micromeso.2005.04.026
State	Published - Sep 15 2005
Externally published	Yes

Keywords

Carbon membranes
Fluoro-polyimide
Intermediate membranes
Thermal treatment
Transport

ASJC Scopus subject areas

General Chemistry
General Materials Science
Condensed Matter Physics
Mechanics of Materials

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10.1016/j.micromeso.2005.04.026

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title = "The evolution of physicochemical and transport properties of 6FDA-durene toward carbon membranes; from polymer, intermediate to carbon",

abstract = "A high Tg material, which is 6FDA-durene (Tg: 425 °C) polyimide, is applied to study the Tg's effect on the evolution of physicochemical and transport properties of membranes from polymeric, intermediate to carbon stages. Tg greatly affects the configurational organization of membranes during pyrolysis especially at the intermediate stage (400-500 °C) and finally influences the pore size and pore size distribution of carbon membranes, which has been mostly ignored by the previous studies. The physicochemical and transport properties in various membrane stages are thoroughly characterized by TGA-FTIR, FTIR-ATR, XRD, thickness and gas transport tests. It is found that the membranes derived from the high Tg polyimides show a significant increase in chain mobility and physicochemical development in the intermediate stage. Interestingly, the gas permeability with annealing temperature show double peaks for medium-size gases such as O2, N2 and CH4, and single peaks for light gases such as He, H2 and CO2. In addition, the ideal selectivity generally shows double minimum values with annealing temperature. These phenomena may arise from the fact that significant physicochemical changes take place around the Tg, while the maximum degradation rate occurs at temperatures 70-100 °C above Tg. As compared with the trade-off line [L.M. Robeson, J. Membr. Sci. 62 (1991) 165], the temperature for membranes derived from the high Tg polyimide to surpass the trade-off line occurs around 450 °C. This temperature is just fall on the intermediate-stage temperature range. The resultant carbon membranes pyrolyzed with 1 °C/min heating rate show better transport performance at low pyrolysis temperatures than those pyrolyzed with 3 °C/ min heating rate. However, when the pyrolysis temperature is elevated to 800 °C, the resultant carbon membranes pyrolyzed by different protocols all show similar and superior performance for gas separation.",

keywords = "Carbon membranes, Fluoro-polyimide, Intermediate membranes, Thermal treatment, Transport",

author = "Lu Shao and Chung, {Tai Shung} and Pramoda, {K. P.}",

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T1 - The evolution of physicochemical and transport properties of 6FDA-durene toward carbon membranes; from polymer, intermediate to carbon

AU - Shao, Lu

AU - Chung, Tai Shung

AU - Pramoda, K. P.

PY - 2005/9/15

Y1 - 2005/9/15

N2 - A high Tg material, which is 6FDA-durene (Tg: 425 °C) polyimide, is applied to study the Tg's effect on the evolution of physicochemical and transport properties of membranes from polymeric, intermediate to carbon stages. Tg greatly affects the configurational organization of membranes during pyrolysis especially at the intermediate stage (400-500 °C) and finally influences the pore size and pore size distribution of carbon membranes, which has been mostly ignored by the previous studies. The physicochemical and transport properties in various membrane stages are thoroughly characterized by TGA-FTIR, FTIR-ATR, XRD, thickness and gas transport tests. It is found that the membranes derived from the high Tg polyimides show a significant increase in chain mobility and physicochemical development in the intermediate stage. Interestingly, the gas permeability with annealing temperature show double peaks for medium-size gases such as O2, N2 and CH4, and single peaks for light gases such as He, H2 and CO2. In addition, the ideal selectivity generally shows double minimum values with annealing temperature. These phenomena may arise from the fact that significant physicochemical changes take place around the Tg, while the maximum degradation rate occurs at temperatures 70-100 °C above Tg. As compared with the trade-off line [L.M. Robeson, J. Membr. Sci. 62 (1991) 165], the temperature for membranes derived from the high Tg polyimide to surpass the trade-off line occurs around 450 °C. This temperature is just fall on the intermediate-stage temperature range. The resultant carbon membranes pyrolyzed with 1 °C/min heating rate show better transport performance at low pyrolysis temperatures than those pyrolyzed with 3 °C/ min heating rate. However, when the pyrolysis temperature is elevated to 800 °C, the resultant carbon membranes pyrolyzed by different protocols all show similar and superior performance for gas separation.

AB - A high Tg material, which is 6FDA-durene (Tg: 425 °C) polyimide, is applied to study the Tg's effect on the evolution of physicochemical and transport properties of membranes from polymeric, intermediate to carbon stages. Tg greatly affects the configurational organization of membranes during pyrolysis especially at the intermediate stage (400-500 °C) and finally influences the pore size and pore size distribution of carbon membranes, which has been mostly ignored by the previous studies. The physicochemical and transport properties in various membrane stages are thoroughly characterized by TGA-FTIR, FTIR-ATR, XRD, thickness and gas transport tests. It is found that the membranes derived from the high Tg polyimides show a significant increase in chain mobility and physicochemical development in the intermediate stage. Interestingly, the gas permeability with annealing temperature show double peaks for medium-size gases such as O2, N2 and CH4, and single peaks for light gases such as He, H2 and CO2. In addition, the ideal selectivity generally shows double minimum values with annealing temperature. These phenomena may arise from the fact that significant physicochemical changes take place around the Tg, while the maximum degradation rate occurs at temperatures 70-100 °C above Tg. As compared with the trade-off line [L.M. Robeson, J. Membr. Sci. 62 (1991) 165], the temperature for membranes derived from the high Tg polyimide to surpass the trade-off line occurs around 450 °C. This temperature is just fall on the intermediate-stage temperature range. The resultant carbon membranes pyrolyzed with 1 °C/min heating rate show better transport performance at low pyrolysis temperatures than those pyrolyzed with 3 °C/ min heating rate. However, when the pyrolysis temperature is elevated to 800 °C, the resultant carbon membranes pyrolyzed by different protocols all show similar and superior performance for gas separation.

KW - Carbon membranes

KW - Fluoro-polyimide

KW - Intermediate membranes

KW - Thermal treatment

KW - Transport

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SN - 1387-1811

VL - 84

SP - 59

EP - 68

JO - Microporous and Mesoporous Materials

JF - Microporous and Mesoporous Materials

IS - 1-3

ER -

The evolution of physicochemical and transport properties of 6FDA-durene toward carbon membranes; from polymer, intermediate to carbon

Abstract

Keywords

ASJC Scopus subject areas

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