Article ID Journal Published Year Pages File Type
7019629 Journal of Membrane Science 2018 33 Pages PDF
Abstract
In present work, the incorporation of nonrearrangable codiamines (mPDA, DMB or TFMB) with different substituted groups into an ortho-hydroxypolyimide (HPI) precursor was applied to modify the gas separation and mechanical performances of resultant thermally rearranged (TR) polybenzoxazole membranes. Evolution of the thermal rearrangement for ortho-hydroxy copolyimide precursors was effectively monitored by the TGA-FTIR, WAXD and PALS measurements. The incorporated non-TR-able codiamines and the thermal treatment protocols have a great effect on the chains packing behavior, free volume, mechanical properties as well as the gas separation behavior of resulted TR-PBOI membranes. These TR-PBOI membranes show high tensile strength of 117-160 MPa and good elongation at break of 7.5-9.0% as thermally treated at 400 °C for 2 h. The t-TR400-2 membrane comprising the TFMB codiamine exhibits a synergistic effect of high gas permeability and high gas pairs selectivity, which is mainly attributed to the loose chains packing resulted from the thermal rearrangement and the substituted bulky -CF3 group that resulting a high fractional free volume (FFV≈0.15). The systematic structure/property relationship studies serve as a guide of materials and process development of commercial TR membranes for gas separation applications.
Related Topics
Physical Sciences and Engineering Chemical Engineering Filtration and Separation
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