A novel poly(acrylic acid)/mica superabsorbent composite was synthesized by graft polymerization reaction between partially neutralized acrylic acid and ultrafine mica mineral powder. The water absorbency of the composite is higher than 1 100 g H2O/g. The influence of the neutralization degree of acrylic acid, as well as of the amounts of mica and crosslinker on the absorbing properties are discussed in this paper.

A comprehensive proton exchange membrane fuel cell (PEMFC) system model is developed, including a pseudo two-dimensional transient multiphase stack model, a one-dimensional transient multiphase membrane humidifier model, a one-dimensional electrochemical hydrogen pump model, an air compressor model with proportion-integral-derivative control and a ribbon-tubular fin radiator model. All sub-models have been rigorously validated against experimental data to guarantee the system model accuracy. The effects of stack operating temperature, gas flow pattern and humidifier structural design are investigated to cast insights into the interaction among stack and auxiliary subsystems. The results indicate that the stack is successfully maintained at required operating temperatures (60 ℃, 70 ℃, 80 ℃) with help of the radiator when the whole system starts from ambient temperature (25 ℃).However, the stack is likely to suffer from membrane dehydration when operated at 70 ℃, and the problem becomes more severe at 80 ℃, causing significant performance deterioration. The water and temperature distribution inside the system are further demonstrated. The co-current flow pattern contributes to better water utilization of the whole system which may lead to higher output performances. But the counter-current flow pattern has positive effects on parameter distribution uniformity inside fuel cell, which is beneficial for the stack durability. As regards the membrane dehydration, it is found that optimizing membrane humidifier area does not fundamentally solve the problem. Increasing humidifier area contributes to higher water vapor transfer rate, however, it results in much slower humidification responses. *Revised Manuscript with Changes Marked Click here to download Revised Manuscript with Changes Marked: Manuscript_revise_2019.9.12(marked).docx

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