Hydrogen Energy

In this paper, the synthesis and characterization of new sulfonated poly(maleimide) is described. Two-step polymerization method was used to prepare the sulfonated poly(maleimide) from maleic anhydride (MA) and p-dimethylamino-azobenzenesulfonic acid (DMBSA). The sulfonation degree of the polymer was regulated through variation of the molar ratio of DMBSA. Flexible, transparent, and mechanically strong membranes were successfully obtained. The membranes were characterized with Fourier transform infrared spectra, 1 H NMR, thermogravimetric analysis, ion-exchange capacity, and proton conductivity measurements. These results showed that the membranes had good thermal stability and exhibited high conductivity.

A design of a circularly polarized planar antenna array of elliptical patches is presented. The designed prototype has been verified experimentally. Elliptical patches produce circular polarization by using a single feed only. A corporate feed network with quarter-wave transformers are used for uniform excitation of all the array elements. Primary advantages of the presented antenna array are structural simplicity, good circular polarization characteristics and no side lobes. Here, the design example is given for 2×2 elliptical patches at 2.8 GHz. Similar procedure can be extended for more number of array elements at the desired frequency of operation to cater the need of communication systems where circular polarization is essential.

In this paper, the effect of the addition of potassium chloride (KCl) by ball milling on the first hydrogenation kinetics of TiFe is reported. After milling, KCl was uniformly distributed on the TiFe’s surface. As-synthesized TiFe does not absorb hydrogen. However, after ball milling with KCl, it absorbed 1.5 wt.% of hydrogen on the first hydrogenation without any thermal treatment. The storage capacity of TiFe with KCl addition is higher than that of the ball milled pure TiFe. The effects of the amount of KCl additive in TiFe and ball milling time on first hydrogenation kinetics are reported. It is noted that, with an increase in KCl amount and ball milling time, hydrogenation kinetics are improved. However, hydrogen storage capacity decreased for both cases.

The Fickian diffusivity of water in Nafion has been shown to exhibit a local maximum. In the present research effort it is shown that this spike vanishes if the equilibrium water content and chemical diffusivity are modeled carefully. Further, it is shown that permeation experiments falsely can generate a local maximum, if a wrong equilibrium water content relation is used. Finally, in order to study the obtained diffusivity model a parameter variation is carried out using a one-dimensional steady-state model. The effect of diffusivity model, surface roughness and water content driving force is studied.