Studies of sulfonated block copolymer and its blends

This paper reports the synthesis and characterization of a sulfonated polym er based on hydrogenated poly(styrene-butadiene) block copolymer (HPBS). Bl ock copolymer ionomers were prepared through sulfonation of part of the pol ystyrene blocks. The free acid samples (HPBS-SH), and their blends with the non-sulfonated polymer (HPBS) and polypropylene (PP) were studied. FTIR wa s used to confirm sulfonation. DMA and DSC analyses have shown that T-g (HP B) remains constant for all the samples studied. Glass transition temperatu res of polystyrene (PS) measured through DMA present an increase of about 3 0 degrees C after sulfonation, diminution (up to 13 degrees C) when the amo unt of HPBS increases in HPBS-SH/HPBS blends and augmentation (up to 28 deg rees C) as the PP content in HPBS-SH/PP blends increases. Complex impedance measurements have shown that proton conductivity of HPBS-SH was about 8 X 10(-3) Ohm(-1) cm(-1), lower values were observed generally in the case of blends. Non-isothermal crystallization of PP was studied using Avrami analy sis. (C) 2000 Elsevier Science Ltd. All rights reserved.