Duk Man Yu

Preparation and characterization of acid-acid blend membranes for direct methanol fuel cell applications

Acid-acid blend membranes were successfully prepared using two types of sulfonated poly(arylene ether sulfone) random copolymers with various ratios (SPAES-BP and SPAES-HPF). The blend membrane properties were investigated using proton nuclear magnetic resonance, thermogravimetric analysis, water uptake, methanol permeability, and proton conductivity measurements. The morphology of the blend membranes varied according to the SPAES-HPF ratio in the blending solution and the nanosized dispersion of the SPAES-HPF in the SPEAS-BP affected the improvement of acid-acid blend membrane properties. Consequentially, the water uptake and dimensional change decreased while the proton conductivity increased in the blend membranes involving a small amount SPAES-HPF compared with that of the SPAES-BP. For the direct methanol fuel cell performance, the power density of SPAES-BP(90)/SPAES-HPF(10)_showed an enhancement of 145 mW/cm2 over that of Nafion 115 (132 mW/cm2).

Surface modification of polyimide films by an ethylenediamine treatment for a flexible copper clad laminate

AbstractThe surfaces of the polyimide films Kapton-E and Upilex-S are modified by ethylenediamine treatment to improve its adhesion to a subsequently deposited copper layer. The changes in the chemical composition, morphology, and adhesion properties of the modified polyimide surface are characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and the 90o peel test. An ethylenediamine polyimide treatment induces amino group formation from the broken imide group. The peel strength of Kapton-E and Upilex-S with a copper layer increases from 0.3 to 0.65 kgf/cm and 0.25 to 0.46 kgf/cm, respectively. The results show that ethylenediamine treatment is a good modification method to greatly increase the adhesion performance of polyimide films to a copper layer.

Poly(amide-co-imide)-poly(trimellitic anhydride chloride-co-4,4′-methylenedianiline) nonwoven/sulfonated poly(arylene ether sulfone) composite membrane for proton exchange membrane fuel cells

AbstractPoly(amide-co-imide)-poly(trimellitic anhydride chloride-co-4,4′-methylenedianiline) (PAI-PTM) blends were prepared for fabricating nonwoven composite membranes by electrospinning method. The characteristics of the membranes were investigated by scanning electron microscopy (SEM), porometer, and universal tensile machine (UTM). Sulfonated poly(arylene ether sulfone) (SPAES) copolymer was synthesized with 50 degrees of sulfonation as a hydrocarbon-based ionomer for proton exchange membrane fuel cells (PEMFCs). The novel composite membrane was fabricated by impregnating SPAES copolymer into the PAI-PTM nonwoven membrane. The PAI-PTM nonwoven membrane exhibited high porosity and adequate mechanical properties, which could improve the dimensional stability (26 vol% decrease) from the swelling of SPAES copolymer in water. For the single cell test, the composite membrane showed comparable performance (1.07 A/cm2 at 0.6 V) to that of Nafion 212 (1.02 A/cm2 at 0.6 V) and outstanding durability in the open circuit voltage (OCV) holding test.

Preparation and properties of sulfonated poly(arylene ether sulfone)/hydrophilic oligomer- g -CNT composite membranes for PEMFC

AbstractWe have synthesized a novel composite membrane composed of hydrophilic oligomer-g-carbon nanotube (CNT) and sulfonated poly(arylene ether sulfone) (sPAES) for proton exchange membrane fuel cell (PEMFC). Hydrophilic oligomer-g-CNT is made by linking sPAES hydrophilic oligomers of either 3 k, 7 k, or 15 k molecular weight to CNTs. Hydrophilic oligomers allow better dispersion of CNTs in the polymer matrix, and the well dispersed CNTs act as a reinforcing agent in the membrane. The sulfonic acid groups on the hydrophilic oligomer-g-CNT form effective water transport channels which can hold more water under low humidity conditions. Therefore, the developed composite membrane shows proton conductivity enhancement of 40% compared to the pristine membrane at 80 °C and 50% relative humidity (RH) condition. Single cell performances and mechanical properties are also improved in the composite membrane. Especially, current density of the composite membrane prepared with 1 wt% hydrophilic oligomer (15 k)-g-CNT shows an 86% increase compared to that of the pristine membrane at 0.6 V, 80 °C, and 50% RH condition.