THE EFFECTS OF PRISTINE AND SULFONATED GRAPHENE OXIDE NANOPARTICLES (GO AND SGO, RESPECTIVELY) ON THE PROTON CONDUCTIVITY OF A CHITOSAN/CHITOSAN SULFATE (CH/CHS) BLEND MEMBRANE WERE INVESTIGATED. THE RESULTS SHOWED THAT SGO CONTAINING MEMBRANES HAD THE HIGHEST PROTON CONDUCTIVITY VALUES AMONG THE PREPARED SAMPLES. ALSO, THE METHANOL PERMEABILITY OF BLENDING MEMBRANES CONTAINING SGO NANOSHEETS WAS LOWER THAN THAT OF THE MEMBRANES CONTAINING GO NANOPARTICLES. ACCORDING TO THE SELECTIVITY PARAMETERS, CH/CHS/5SGO MEMBRANE WOULD BE THE MOST PROMISING CANDIDATE FOR DMFC APPLICATIONS. FINALLY, THE EXPERIMENTAL RESULTS WERE COMPARED WITH THE PREDICTION FROM A RECENTLY DEVELOPED MODEL FOR INVESTIGATION OF PROTON CONDUCTIVITY.

AN IONIC CONDUCTIVITY EQUATION WAS COMBINED WITH A THERMODYNAMIC MODEL FOR PREDICTING THE PROTON CONDUCTIVITY OF A PHOSPHORIC ACID-DOPED POLYBENZIMIDAZOLE (H3PO4-DOPED MPBI) MEMBRANE. PROTON DIFFUSION COEFFICIENT AND PROTON CONDUCTIVITY WERE CALCULATED AT DIFFERENT TEMPERATURES. IT WAS FOUND THAT WITH INCREASING THE TEMPERATURE, THE DIFFUSION COEFFICIENT AND CONDUCTIVITY OF PROTON ENHANCE AND THE TEMPERATURE DEPENDENCE OF CONDUCTIVITY OF H3PO4-DOPED MPBI MEMBRANE FOLLOWS THE SIMPLE ARRHENIUS BEHAVIOR. A GOOD AGREEMENT WAS ALSO OBSERVED BETWEEN THE THEORETICAL AND EXPERIMENTAL DATA AT TEMPERATURES LESS THAN 80 OC. HOWEVER, SOME DEVIATIONS FROM EXPERIMENTAL DATA WERE OBSERVED AT HIGH TEMPERATURES. THIS CAN BE ATTRIBUTED TO THE EXISTENCE OF SOME SPECIFIC INTERACTIONS BETWEEN THE PHOSPHORIC ACID AND POLYBENZIMIDAZOLE WHOSE EFFECTS WERE NOT INCLUDED IN THE CHEMICAL POTENTIAL AND INTERACTION PARAMETER EQUATIONS.

THIS PAPER DESCRIBED THE FABRICATION OF PROTON EXCHANGE MEMBRANE (PEM) BASED ON SULFONATED POLYETHER IMIDE (SPEI) -DEGREE OF SULFONATION ~73% - IN THE PRESENCE OF DIFFERENT AMOUNTS OF POLYETHYLENE GLYCOL (PEG) (MW ~ 1000),AND DIMETHYL ACETAMIDE (DMAC) WAS USED AS SOLVENT. THE SAMPLES WERE HEATED AT 120OC, FOR DRYING. WATER UPTAKE AND PROTON CONDUCTIVITY RESULTS SHOWED THAT ADDITION OF THE PEG TO SULFONATED POLYETHER IMIDE (PEI) IMPROVE WATER UPTAKE AND ION EXCHANGE CAPACITY (IEC). IN PARTICULAR, THE MAXIMUM PROTON CONDUCTIVITY WAS OBSERVED IN SAMPLES CONTAINING 20 WT% PEG. SO, PROTON CONDUCTIVITY OF THE MEMBRANE REACHED UP TO 11.7 MS.CM-1 AT 75OC.

AN IONIC CONDUCTIVITY EQUATION WAS COMBINED WITH A THERMODYNAMIC MODEL TO PREDICT PROTON CONDUCTIVITY OF THE NAFION 117 MEMBRANE. PROTON CONDUCTIVITY WAS CALCULATED AT DIFFERENT VOLUME FRACTIONS OF WATER (WATER CONTENT) AND TEMPERATURES. THE RESULTS SHOWED THAT PROTON CONDUCTIVITY OF THE NAFION 117 MEMBRANE IS ENHANCED BY INCREASING THE TEMPERATURE AND WATER VOLUME FRACTION. A GOOD AGREEMENT WAS OBSERVED BETWEEN THE THEORETICAL AND EXPERIMENTAL DATA OVER THE TEMPERATURE RANGE OF 298-353 K AND WATER VOLUME FRACTION RANGE OF 0.1-0.4.

IN THE PRESENT STUDY, THE SELF-HUMIDIFYING NANO COMPOSITE MEMBRANES BASED ON SULFONATED POLY ETHER KETONE (SPEEK) AND CS2.5H0.5PW12O40 SUPPORTED PT CATALYST (PT-CS2.5H0.5PW12O40 CATALYST OR PT-CS2.5) WERE FABRICATED. PROTON CONDUCTIVITY IS ALWAYS USED TO EVALUATE THE PRACTICABILITY OF NEWLY-DEVELOPED MEMBRANES. PROTON CONDUCTIVE MEMBRANE IS GENERALLY EVALUATED BY MEASURING ITS CONDUCTIVITY ALONG THE PLANES OF THE MEMBRANE. HOWEVER, THE NEED TO MEASURE ITS CONDUCTIVITY IN THE DIRECTION OF THICKNESS HAS RECENTLY BEEN RECEIVING GREATER ATTENTION. THE RESEARCH WORK IS AIMED AT FINDING A WAY TO STABLY AND PRECISELY MEASURE THE CONDUCTIVITY OF A MEMBRANE IN THE DIRECTION OF THICKNESS AT DIFFERENT TEMPERATURE AND HUMIDITIES AND OBTAINING A MATHEMATICAL RELATIONSHIP FROM THE EXPERIMENTAL DATA.

PBI (POLYBENZIMIDAZOLE) -MNTIO3 (PMT) NANOCOMPOSITE MEMBRANES HAVE BEEN PREPARED WITH SOLUTIONS CASTING METHOD. THE NANOCOMPOSITE MEMBRANES WERE CHARACTERIZED BY USING AC IMPEDANCE SPECTROSCOPY (IS), FOURIER TRANSFORM INFRARED SPECTROSCOPY (FT-IR), SCANNING ELECTRON MICROSCOPY (SEM) COUPLED WITH ENERGY DISPERSIVE X-RAY (EDX) AND THERMOGRAVIMETRIC ANALYSIS (TGA). THE RESULTS SHOWED THAT THE WATER UPTAKE AND PROTON CONDUCTIVITY OF THE PMT NANOCOMPOSITE MEMBRANES WERE HIGHER THAN THAT OF PBI BASED MEMBRANE BECAUSE OF HYDROPHILIC NATURE OF MNTIO3 NANOPARTICLES. WHEN THE PREPARED MEMBRANES DOPED WITH PHOSPHORIC ACID (PA), DUE TO PROTON TRANSFER FROM PA, PA-PMT NANOCOMPOSITE MEMBRANES DISPLAYED HIGHER PROTON CONDUCTIVITY THAN PMT NANOCOMPOSITE MEMBRANES. INCORPORATION OF NANOPARTICLES IN NANOCOMPOSITE MEMBRANES INCREASED THE THERMAL STABILITY OF PA-PMT NANOCOMPOSITE MEMBRANES COMPARED WITH PA-PBI MEMBRANES.

NANOCOMPOSITE MEMBRANES BASED ON THE MPVDF/PMMA-CO-PAMPS/SILICA NANOPARTICLE WERE PREPARED VIA SOLVENT CASTING METHOD IN THE PRESENCE OF VARIOUS AMOUNTS (0-10 WT%) OF SILICA NANOPARTICLES. NANOCOMPOSITE MEMBRANES WERE THEN CHARACTERIZED BY FTIR, IMPEDANCE SPECTROSCOPY AND THERMOGRAVIMETRIC ANALYSIS (TGA). THE HIGHEST PROTON CONDUCTIVITY (19 MS/CM) WAS OBSERVED FOR MPVDF/PMMA-CO-PAMPS MEMBRANE PREPARED IN THE PRESENCE OF 5 WT% SILICA NANOPARTICLES.