5 years ago

Evaluation of Gas Transport Properties of Highly Rigid Aromatic PI DPPD-IMM/PBI Blends

Evaluation of Gas Transport Properties of Highly Rigid Aromatic PI DPPD-IMM/PBI Blends
José Luis Santiago-García, José Manuel Pérez-Francisco, María Isabel Loría-Bastarrachea, Manuel Aguilar-Vega
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/CH4 and O2/N2 gas 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/N2 and CO2/CH4 gas 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 %).

Publisher URL: http://dx.doi.org/10.1021/acs.iecr.7b02074

DOI: 10.1021/acs.iecr.7b02074

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.