In order to investigate a relationship between chemical structure of coking coals and their thermoplasticity during their carbonizationn, evaluation of both hydrogen transfer reaction and heat treatment coupled with SEM observation was conducted along with measurement of SPE/ MAS 13 C NMR of virgin coals. The hydrogen transfer reaction from coal to hydrogen acceptor was carried out at 420 °C for 5 min. In the case using anthracene as acceptor, 0.6-1.1 mg of H 2 was transferred from 1 g of daf coal to the acceptor. A correlation between the weight of hydrogen transferred and % carbon of each coal (coal rank) showed a similar tendency to that between Gieseler fluidity and coal rank. This result suggests that the quantities of donatable hydrogen could be correlated strongly with the development of plasticity. To obtain the insight into the amounts of functional groups involved in releasing hydrogen, solid state 13 C NMR of sample coals was measured, the results indicating the presence of somewhat correlation between the concentrations of bridge methylene groups linking two aromatic moieties and maximum fluidities. Heat treatment of the coals up to their softening temperature, resolidification temperature, and 1000 °C was also conducted, the combination of crystallite parameters of the resulting chars and their SEM observation suggesting that lamellar structures of coal became disordered upon heating and then turned to the ordered structures as the heating proceeds. On the basis of the above results, chemical structural changes during carbonization process are discussed.

The nature of proton dynamics as well as a pendant side chain's ability for proton dissociation and capture in low-hydration sulfonated polyethersulfone (SPES) (lambda = 2, 4) have been studied theoretically by means of quantum chemical calculations and first-principles molecular dynamics simulations. A detailed comparison of results on SPES with those on Nafion has been made. It is found that the sulfonic groups of Nafion tend to dissociate protons more easily than do those of SPES. Hydration by four water molecules allows the dissociation of a proton from the sulfonic groups in both SPES and Nafion. The results of the first-principles MD simulations on SPES show that the nature of proton transfer kinetics for both hydration levels is very similar. Compared with low-hydration Nafion, however, hydration around the sulfonic groups in SPES is not sufficient to fully dissociate protons from the sulfonic groups, which results from the fact that some of the water molecules participate in hydrating SO(2) groups in SPES rather than SO(3)(-). Such a feature affects the performance of SPES under low-hydration conditions.

We investigated the 1 H time-dependent self-diffusion coefficients, D eff , in perfluorinated membrane with low and high water contents (6% and 24%) at the temperature range from 233 to 323 K. The D(∆ eff ) was measured as a function of the diffusion time, ∆ eff , from 1 to 100 ms by field gradient NMR techniques. The oscillating gradient spin-echo sequence (OGSE) and the bipolar pulse longitudinal eddy current delay sequence (BPPLED) were employed to examine the D(∆ eff ) of the short and long ∆ eff . The results showed that the 1 H self-diffusion coefficients were dependent on ∆ eff less than 2 ms due to restricted geometry and were constant beyond 3 ms. The tortuosity, R, and surface-to-volume ratio of pore, S/V, for proton diffusion were estimated as geometrical parameters at each temperature. The values of S/V revealed the existence of micron-scale restricted structure compared with well-known nanometer-sized domain in perfluorinated membrane. Activation energy, E a , of diffusion was also evaluated from the temperature dependence of diffusion at temperature above 263 K. The E a in the membrane and in the bulk water were almost the same at the temperature range above 263 K while it had some difference at lower temperature.

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