The variation of lamellar structures of poly(styrenesulfonic acid)-grafted poly (ethylene-co-tetrafluoroethylene) proton exchange membranes dependence on preparation procedures and grafting degree (GD) was investigated by small angle X-ray scattering. | TAÏP CHÍ PHAÙT TRIEÅN KH&CN, TAÄP 18, SOÁ T4- 2015 Study of lamellar structures of grafttype fluorinated proton exchange membranes by small-angle X-ray scattering: preparation procedures and grafting degree dependence for fuel application Tran Duy Tap Pham Minh Hien Nguyen Hoang Anh Luong Tuan Anh University of Science, VNU-HCM Luu Anh Tuyen Center for Nuclear Techniques HCMC (Received on December 10 th 2014, accepted on September 23rd 2015) ABSTRACT The variation of lamellar structures of poly(styrenesulfonic acid)-grafted poly (ethylene-co-tetrafluoroethylene) proton exchange membranes dependence on preparation procedures and grafting degree (GD) was investigated by small angle X-ray scattering. The detail structures of lamellar including lamellar period L, thickness of lamellar crystal Lc, thickness of lamellar amorphous La, and linear crystallinity Lc/L were examined by a 1D correlation function. The lamellar structures were recognized at the grafting step and did not change under the sulfonation process. With GD 79 %, Lc significantly decreased (corresponding to the increase of La) and then retained in the GDs of 79-117 %. Note that the retained values of Lc, La, and linear crystallinity in the GDs of 79-117 % are the origin of high conductivity and mechanical strength of membranes under severe operation conditions for fuel cell applications. Keywords: small angle X-ray scattering, proton exchange membrane, lamellar, 1D correlation function INTRODUCTION Polymer electrolyte membranes (PEMs) have been considered as one of the key components for fuel cell performance because their properties required for fuel cell applications, such as ionic conductance, mechanical strength, and thermal stability, are directly related to their power generation efficiency and durability under severe operating conditions [1]. The pre-irradiation grafting method, in which polymer substrates are first irradiated using a quantum beam and then immersed in a monomer
