مرکز منطقه ای اطلاع رساني علوم و فناوري -

چكيده لاتين :

Metal-incorporated poly(amide 12-block-tetramethylenoxide) (PA12-co-PTMO) copolymer was used for studying facilitated transport of olefines through new composite membranes. The metals incorporated were silver {Ag(I)} and copper {Cu(I)}. Tests were carried out at room temperature (25±2°C) to determine the selectivity and permeability of these membranes to ethylene and ethane gas. The membranes prepared by mixing in solution the copolymer with silver (AgBF4) or copper (CuBF4) salt show a ethylene/ethane selectivity much higher than that of pure PA12-co-PTMO. The membranes were also characterized by Fourier Transform Infra Red (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) in order to understand the structural feature responsible for the observed behaviour. The IRFT spectrum indicate that Ag+ and Cu+ ions are developing interactions with the copolymer. The permeation results obtained with copper containing membranes show that CuBF4 salt introduction in the copolymer tends to reduce ethane permeability. This phenomenon is explained by a diminution of the free volume caused by a decrease of the interchain distance due to the formation of metal ions-polymer matrix complexes. At the same time, for ethylene, the decrease in permeability observed at low salt content is recouped rapidly, when the salt content increases, by a dramatic increase of the permeability which attains 10 times that of the pure PA12-co-PTMO. This behaviour is attributed to the facilitated transport mechanism of the ethylene molecules able to develop specific interactions with the incorporated metal ions. It results from these two antagonistic phenomena a multiplication by 18 of the ethylene/ethane selectivity of the pure copolymer when the CuBF4 content of the composite attains 60%.