FisMat2017 - Submission - View

Abstract's title: Gas transport and free volume in epoxy resin nanocomposite membranes
Submitting author: David Roilo
Affiliation: Department of Physics, University of Trento
Affiliation Address: Department of Physics, University of Trento, Via Sommarive, 14, 38123 Povo (TN) ITALY
Country: Italy
Oral presentation/Poster (Author's request): Poster
Other authors and affiliations: Pushkar N. Patil (Department of Physics, University of Trento), Roberto S. Brusa (Department of Physics, University of Trento), Antonio Miotello (Department of Physics, University of Trento), Stefano Aghion (Department of Physics and L-NESS, Politecnico di Milano), Rafael Ferragut (Department of Physics and L-NESS, Politecnico di Milano), Riccardo Checchetto (Department of Physics, University of Trento)

Polymers and polymer nanocomposites are receiving considerable attention in packaging and gas separation technologies. A detailed understanding of the gas transport mechanism through polymer layers requires a characterization of the membrane structure at nano-scale level. The transport of different gases (CO2, N2, H2) in epoxy resin membranes with different crosslink density has been studied by a gas phase permeation technique. The free volume structure of the samples has been analyzed by Positron Annihilation Lifetime Spectroscopy (PALS). The gas transport data (diffusivity and solubility values as functions of temperature and cross-linking density) in the epoxy resins was explained in terms of the free volume theory for diffusion in polymers, thanks to the free volume data obtained from PALS analysis. Well characterized epoxy resins were used for the preparation of Mixed Matrix Membranes using different nanofiller particles (Few Layers Graphene, Metal Organic Frameworks, Carbon Nanotubes). For a class of samples (i.e. the Few Layer Graphene - loaded epoxy resins), permeation and PALS measurements have revealed a reduction both in free volume of the polymeric matrix and in gas permeability, with respect to the pure epoxy resin. The observation can be explained by assuming a localized rigidification of the polymeric matrix close to the matrix-filler interface. Starting from the PALS measurements, the thickness of the rigidified layer could be estimated: this result is compatible with the permeability reduction of the nanocomposite membrane as predicted by the Maxwell model for the permeability of Mixed Matrix Membranes.