POLYVINYL ALCOHOL BASED PROTON CONDUCTOR MEMBRANE SYNTHESIS AND CHARACTERIZATIONS


Thesis Type: Postgraduate

Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2010

Thesis Language: Turkish

Student: Derya ORUÇ

Supervisor: MUZAFFER BALBAŞI

Abstract:

Proton conducting polymer electrolyte membranes attract considerable attention because they are key-components in polymer electrolyte membrane fuel cells (PEMFCs). Polymer electrolyte membrane fuel cells (PEMFCs) are promising environmentally friendly and efficient power sources for a wide range of different applications. In this study, it is aimed to obtain proton conductive membranes for PEMFCs. In this study, polyvinyl alcohol (PVA) based, H3PO2 doped, composite membranes were synthesized. To obtain chemical and mechanical stable membranes glutar dialdehyde (GA) was used by treating different crosslinking times. After membranes were synthesized, some characterization property tests such as; Fourier transform infrared spectroscopy (FT-IR), termal gravimetric analysis (TGA), capacity of water uptake and swelling degree, capacity of ion exchange (IEC), electrochemical impedance measurements (EIM), tensile strength tests and Fenton test for chemical stability were performed. The highest proton conductivity value was obtained from the membrane coded as PVA/40HPA+HEAT under the experimental conditions of 70 ºC at absence of 0,01 M H2SO4. This value is 1,89x10-2 Scm-1. Chemical and mechanical stabilities of PVA/40HPA+HEAT and 15GA/PVA/40HPA+HEAT membranes were compared and it was seen that PVA/40HPA+HEAT membrane showed good mechanical stability but 15GA/PVA/40HPA+HEAT membrane showed good chemical stability. So 15GA/PVA/40HPA+HEAT membrane choosed for membran electrode assembly (MEA). But pretreatments done on membrane decreased the stability of membrane. The properties those are the results of the characterization tests show that synthesized membranes can be used in fuel cells. But their mechanical and chemical properties are poor for using PEMYH systems. Mechanical and chemical stabilities of these membranes can be improved by using different crosslinking agents and synthesis methods.