Preparation and gas permeation properties of biodegradable polymer/layered silicate nanocomposite membranes

Biodegradable polymer/layered silicate nanocomposite membranes were prepared by solution casting method for the application of dehumidification and gas separation. The intercalation and exfoliation of clay in the prepared nanocomposite membranes were confirmed through X-ray diffraction study (XRD). Their thermal and mechanical properties were observed by using Thermo-gravimetric analysis (TGA) and Universal Testing Machine (UTM), respectively. Gas and vapor permeation properties were examined to investigate the effect of the intercalated nanocomposite into membranes. Both gas and vapor permeabilities of the prepared nanocomposite membranes were found to decrease with the increase of clay content. They proved their particular barrier property through intercalation of clay.

1.0 0.5 0.0 CO2 O2 N2 3.25 3.30 3.35 3.40 3.45 3.50 3.55 3.60 3.65 The kinetic diameter of gas molecules (Å) (b) 2.5 PLA PLA-Closite 30B 0.1wt. % PLA-Closite 30B 0.2wt. % PLA-Closite 30B 0.4wt. % PLA-Closite 30B 0.8wt. % 2.0 Permeability [Barrer] From these results, it was confirmed that gas permeabilities of PLSNMs decreased more than those of PLA membranes. The similar barrier feature was observed through the comparison of gas permeabilities in PLSNMs for O2, N2, CO2. The organoclay was found to behave as the barrier against gas molecules to pass through polymer substrate. It was also found that gas permeabilities of the same PLSNMs increased according to the order of the kinetic diameter of permeated gas ˚ ˚ molecules, [N2 (3.64 A) > O2 (3.46 A) > CO2 ˚ )] as shown in Fig. 7. The least decrease (3.3 A of permeability for CO2 was due to the smallest kinetic diameter and the largest molecular weight [14–16].