Sulphonation of polystyrene-butadiene rubber with chlorosulphonic acid for proton exchange membrane: Kinetic study

• Published in: Journal of applied polymer science 2010-06, Vol.116 (6), p.3473-3479
• Main Authors: Idibie, C.A, Abdulkareem, A.S, Pienaar, H.C. vZ, Iyuke, S.E, vanDyk, L
• Format: Article
• Language: English
• Subjects: Applied sciences; degree of sulphonation; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Exchange resins and membranes; Forms of application and semi-finished materials; Fuel cells; Indication; Infrared radiation; kinetic and activation energy; Membranes; Phenyls; Polymer industry, paints, wood; polystyrene-butadiene rubber; proton conductivity; Reaction kinetics; Reproduction; Rubber; Spectroscopy; Technology of polymers
• ISSN: 0021-8995; 1097-4628; 1097-4628
• DOI: 10.1002/app.31888

Proton exchange membrane for fuel cell application was synthesized from a hydrophobic polystyrene-butadiene rubber (PSBR) via sulphonation at different temperatures (22, 35, 55, 65, and 75°C) and varying time with chlorosulphonic acid. Infra-red spectroscopy (IR) and proton nuclear magnetic resonance (¹H-NMR) were used to confirm the occurrence of sulphonation. Sulphonation occurred only on the phenyl ring with a maximum degree of sulphonation of 70.96 mole percent. Consequently, 10⁻³-10⁻² S/cm proton conductivity was achieved. Two models for the reaction kinetics were investigated: first-order reversible and first-order irreversible, respectively. However, the reaction kinetic was found to obey the first-order reversible model. The activation energy (Ea) of the reaction was calculated to be 41.56 kJ/mol of PSBR repeat unit, which is an indication that the reaction is nonspontaneous.