High-Energy Ion Treatment of Lavsan Films Followed by Controlled Track Etching to Obtain Asymmetric Gas-Separation Membranes

Abstract

The structure and gas transport properties of polymer membranes prepared from commercial Lavsan™ (polyethylene terephthalate based material) films by irradiation of the polymer films with Ar ions, followed by etching in an NaOH solution, were studied. Analysis of the polymer structure by differential scanning calorimetry showed that irradiation of the Lavsan™ matrix with Ar ions (energy 2.4 MeV nucleon⁻¹, fluence 6 × 10⁷ cm⁻²) led to a 20–30% decrease in the degree of crystallinity. The permeability of the new membranes to He, H₂, O₂, Ar, N₂, CH₄, CO₂, and H₂/CH₄ mixture was evaluated. UV sensitization allows a fourfold increase in the permeability of the Lavsan™-based films to the gases tested relative to the films etched without preliminary UV irradiation. The composition of the H₂/CH₄ gas mixture does not influence the separating properties of the membranes, and the mixture separation factor coincides with the ideal value of the gas selectivity.