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8. Sulfonated aromatic copoly(ether–amide) membranes II

Author

Sosa-González, Wadi Elim, primary, Palí-Casanova, Ramón del Jesús, additional, Pérez-Padilla, Yamile, additional, Loría-Bastarrachea, María Isabel, additional, Santiago-García, José Luis, additional, and Aguilar-Vega, Manuel de Jesús, additional

Published
2017
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10. Evaluation of Gas Transport Properties of Highly Rigid Aromatic PI DPPD-IMM/PBI Blends

Author

Pérez-Francisco, José Manuel, Santiago-García, José Luis, Loría-Bastarrachea, María Isabel, and Aguilar-Vega, Manuel

Abstract

In this work we discuss the gas transport properties behavior of dense blend membranes of a high free volume polyimide PI DPPD-IMM with PBI using the latter polymer in an attempt to enhance gas selectivity. Thermal and mechanical properties of dense blend membranes were also evaluated. The aim is to test the use of PBI as a gate polymer for establishing a window to enhance selectivity of CO2/CH4and O2/N2gas pairs with a minimum loss of gas permeability. Wide-angle X-ray diffraction measurements show that PI DPPD-IMM has an open structure with a d-spacing maximum at 5.4 Å, which is not affected when PBI concentration in the blends is lower than 25 wt %. This reflects a moderate loss of gas permeability as compared to PI DPPD-IMM. Blends with PBI concentrations 50 wt % or above presented a shift in WAXD toward 4.4 Å. It is found that as PBI concentration increases in the blend, there is an enhanced selectivity for O2/N2and CO2/CH4gas pairs duplicating their value with respect to PI DPPD-IMM and following closely the slope of the Robeson plot. Activation energies for permeation confirm that the PI DPPD-IMM microstructure is preserved at low PBI concentration since they barely increase for blends containing <25 wt % PBI. Gas permeability coefficients were fitted to different prediction models whose analysis confirms that the blends are heterogeneous. The best relationship between gas permeability and gas pair selectivity is located in the region where the blend presents high fractional free volume (FFV) (PBI concentration ≤25 wt %).

Published
2024
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12. Effect of Sulfonic Groups Concentration on IEC Properties in New Fluorinated Copolyamides.

Author

Pali-Casanova, Ramón de Jesús, Yam-Cervantes, Marcial Alfredo, Zavala-Loría., José del Carmen, Loría-Bastarrachea, María Isabel, Aguilar-Vega, Manuel de Jesús, Dzul-López, Luis Alonso, Sámano-Celorio, María Luisa, Crespo-Álvarez, Jorge, García-Villena, Eduardo, Agudo-Toyos, Pablo, and Méndez-Martínez, Francisco

Subjects
ARAMID fibers, PROTON conductivity, PROTON exchange membrane fuel cells, POLYAMIDES, MOLECULAR weights, YOUNG'S modulus
Abstract

Seven aromatic polyamides and copolyamides were synthesized from two different aromatic diamines: 4,4′-(Hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline (HFDA) and 2,4-Aminobenzenesulfonic acid (DABS). The synthesis was carried out by polycondensation using isophthaloyl dichloride (1SO). The effect of an increasing molar concentration of the sulfonated groups, from DABS, in the copolymer properties was evaluated. Inherent viscosity tests were carried out to estimate molecular weights. Mechanical tests were carried out under tension, maximum strength (σ max), Young's modulus (E), and elongation at break (εmax) to determine their mechanical properties. Tests for water sorption and ion exchange capacity (IEC) were carried out. Proton conductivity was measured using electrochemical impedance spectroscopy (EIS). The results indicate that as the degree of sulfonation increase, the greater the proton conductivity. The results obtained showed conductivity values lower than the commercial membrane Nafion 115 of 0.0065 S cm−1. The membrane from copolyamide HFDA/DABS/1S0-70/30 with 30 mol DABS obtained the best IEC, with a value of 0.747 mmol g−1 that resulted in a conductivity of 2.7018 × 10−4 S cm−1, lower than the data reported for the commercial membrane Nafion 115. According to the results obtained, we can suggest that further developments increasing IEC will render membranes based on aromatic polyamides that are suitable for their use in PEM fuel cells. [ABSTRACT FROM AUTHOR]

Published
2019
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