Separation Technology,
M. Azimi; S.J. Peighambardoust
Volume 14, Issue 3 , August 2017, , Pages 65-81
Abstract
In this work, we prepared the nafion/montmorillonite/heteropolyacid nanocomposite membranes for direct methanol fuel cells (DMFCs). The analyses such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) were conducted to characterize the filler dispersion ...
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In this work, we prepared the nafion/montmorillonite/heteropolyacid nanocomposite membranes for direct methanol fuel cells (DMFCs). The analyses such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) were conducted to characterize the filler dispersion and membrane structure in prepared nanocomposite membranes. XRD patterns of nafion-CsPW-MMT nanocomposites membranes showed the exfoliated structure of membranes by adding MMT and CsPW. SEM-EDXA results showed proper dispersion of nanoparticles in the membrane matrices. Addition of CsPW-MMT to nafion membranes increases water uptake and IEC due to increase hydrophilic groups in membranes. The proton conductivity results showed that proton conductivity increases by increasing amount of CsPW and decreasing of clay content in the membrane. Methanol crossover through polymer electrolyte membranes is a critical issue and causes an important reduction of performance in DMFCs. The developed intercalated nafion/CsPW/MMT nanocomposite membranes have successfully improved the membrane barrier properties due to the unique feature of MMT which contributed to the formation of a longer pathway towards methanol across the membrane. The lowest methanol crossover of the developed membranes in this study was 1.651×10-6 cm2 s-1 which was lower than re-cast nafion membrane (2.078×10-6 cm2 s-1). The methanol permeability was significantly reduced by the incorporation of MMT and increased by addition of CsPW in the nafion membrane. Finally, according to the selectivity results, the nafion-MMT-CsPW nanocomposite membrane with MMT mass fraction of 2.5% and CsPW mass fraction of 8% shows the best membrane selectivity and this nanocomposite membrane could be suitable for application in DMFCs.
Polymer Engineering and Technology,
Seyed Jamaleddin Peighambardoust; Ramin Faridvand; Abolfazl Shenavar
Volume 13, Issue 4 , November 2016, , Pages 62-70
Abstract
In this study, in-situ bulk polymerization was investigated for obtaining flame retardant polystyrene (PS). The halogenated and phosphoric compounds were used as flame retardant additives and Perkadox 30 was used as a synergist. The flammability of the PS was evaluated by thermogravimetric analyzer (TGA), ...
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In this study, in-situ bulk polymerization was investigated for obtaining flame retardant polystyrene (PS). The halogenated and phosphoric compounds were used as flame retardant additives and Perkadox 30 was used as a synergist. The flammability of the PS was evaluated by thermogravimetric analyzer (TGA), limiting oxygen index (LOI) and UL-94 tests. The results show that polymerization process for production of flame retardant polystyrene needs lower amount of flame retardant additives compare with the process for production of flame retardant composites. Furthermore, using Perkadox 30 as a synergist lowers the loading of flame retardant additives. LOI tests show that flame retardant polystyrene synthesized by adding at least 0.35 % (w/w) hexabromocyclododecane (HBCD) during polymerization. TGA analysis confirms that with addition of HBCD the degradation temperature decreases and weight loss occurs quickly. The degradation tempresure of the sample consist of 0.8 % (w/w) HBCD was lower than the sample consist of 0.35 % (w/w) HBCD and 0.45 % (w/w) triphenylphosphate (TPP). The pure polystyrene didn’t pass the UL-94 test because of inflammability and greater dripping. For samples with HBCD, shorter time needed to quench the flame and these samples passed the UL-94 test. On the other hand, greater dripping of polymer melt led to transmission of UL-94 rate from V0 to V2. It is also observed that flaming rate for samples with TPP was very low and dripping didn’t occur.