Studies of sulfonated block copolymer and its blends

This paper reports the synthesis and characterization of a sulfonated polymer based on hydrogenated poly(styrene–butadiene) block copolymer (HPBS). Block copolymer ionomers were prepared through sulfonation of part of the polystyrene blocks. The free acid samples (HPBS–SH), and their blends with the non-sulfonated polymer (HPBS) and polypropylene (PP) were studied. FTIR was used to confirm sulfonation. DMA and DSC analyses have shown that Tg (HPB) remains constant for all the samples studied. Glass transition temperatures of polystyrene (PS) measured through DMA present an increase of about 30°C after sulfonation, diminution (up to 13°C) when the amount of HPBS increases in HPBS–SH/HPBS blends and augmentation (up to 28°C) as the PP content in HPBS–SH/PP blends increases. Complex impedance measurements have shown that proton conductivity of HPBS–SH was about 8×10−3 Ω−1 cm−1, lower values were observed generally in the case of blends. Non-isothermal crystallization of PP was studied using Avrami analysis.