The influence of polyvinyl alcohol concentration toward conductivity and permeability of chitosan–montmorillonite composite membrane Scientific paper

Abstract

The composite membrane is synthesized using chitosan as a matrix membrane with montmorillonite (MMT) as a filler and modified using poly­vinyl alcohol (PVA). The main aim of this study is to find out the influence of PVA concentration and the working temperature toward the permeability of chitosan–MMT/PVA composite membrane. Fourier transform infrared spectro­scopy (FTIR) characterization is performed in order to identify the interaction between the chitosan matrix and the modified MMT with PVA. The presence of new absorption at 1116.82 and 619.17 cm^-1 indicated the interaction bet­ween MMT and PVA. Further, the widening of OH absorption indicated the hydrogen bond which is formed between chitosan matrix and PVA. This inter­action is also demonstrated by the evenly distributed surface on scanning elec­tron microscope (SEM) topography analysis. The thermal stability of compo­site membrane is determined by thermal gravimetry analysis (TGA). In addit­ion, the composite membrane containing PVA has four patterns decomposed. When the TVA is absent from the composite membrane, it has three decom­position pat­terns, which are shown by TGA analysis. Based on its tensile strength, the composite membrane has good mechanical properties. The proton conductivity of the composite membranes are directly proportional to the PVA concen­tration. On the other hand, the methanol permeability of composite membranes is inversely proportional with the PVA concentration. The highest proton con­ductivity was obtained with the addition of 2 % PVA of 2.94×10^-4 S cm^-1. Further, it also has the lowest methanol permeability with the value of 5.05×10-6 cm² s^-1. As a result, the crosslinked composite membrane chitosan–MMT pre­pared by PVA-crosslinking technique has the potential to be exp­loited for the direct methanol fuel cell application.