Thesis (M.Eng.)--Chulalongkorn University, 2008

This work aimed to study the effects of modified Montmorillonite clay (m-MMT) loading on the mechanical and thermal properties of the Nafion®/m-MMT composite membrane prepared by solution mixing method. Nafion® perfluorinated resin (5 wt% in lower aliphatic alcohol and water) was mixed with m-MMT (Bentone SD®1) at 0, 3, 6, and 10 phr. The structures of the composite membranes were studied by XRD. Their performances were determined in terms of water uptake, ion exchange capacity (IEC), thermal and mechanical properties. The XRD results showed that the interlayer spacing of m-MMT was decreased when incorporated into Nafion® matrix. Hence, the Nafion® matrix did not intercalate into interlayer spacing of m-MMT and the composite obtained was of a conventional composite type. The water uptake of Nafion®/m-MMT composite membrane increased with increasing amount of m-MMT in Nafion® matrix but the IEC values of Nafion®/m-MMT composite membranes decreased. These effects would balance each other out and the proton conductivity of Nafion®/m-MMT composite membranes would not differ from the pristine Nafion® membrane. The elastic moduli of soaked Nafion®/m-MMT composite membranes were about equal to the soaked pristine Nafion® membrane but the elongation at break of the soaked Nafion®/m-MMT composite membranes were lower. Therefore, the incorporation of this m-MMT into Nafion® matrix at least helped reduce the decay of these mechanical properties by counteracting the effects of increasing water uptake in the composite membranes.