Measurements are reported for the sorption equilibrium and transport of water vapor into polyaniline (PANI)
powders and asymmetric, microporous hollow fibers. Equilibrium isotherms at 298 K were measured on
powders doped with 13 different organic and inorganic acids to change the polyaniline from its emeraldine
base, PANI-EB (insulating) form, to the emeraldine salt, PANI-ES (conducting) form. The powders were
exposed to air streams of varying relative humidity (RH) from 15 to 80%. The four acid dopants, H3PO4,
HPF6, HBF4, and CF3SO3H, provided the highest water sorption figures-of-merit and also displayed nonlinear
isotherms. At 50% RH, these four doped powders adsorbed 0.9−1.6 molecules of water per PANI-ES repeat
unit. Measurements of the sorption kinetics on the hollow fibers were done with one dopant acid, H3PO4.
The data were obtained under exposure to air streams at an ambient pressure of ∼0.1 MPa with relative
humidity ∼50% and temperatures of 300−309 K. The sorption process was well-described by unsteady Fickian
diffusion into an infinite hollow cylinder. The asymmetric and porous nature of the hollow fiber's wall was
represented by using an effective medium approach. The quantitative adsorption/desorption rates and equilibrium
capacities depended on the experimental conditions with the measured water capacities being between 33
and 75 (mg of H2O)/(g of dry polymer) under most conditions, though at the highest relative humidity (∼80%
at 300 K) the fiber adsorbed almost 250 (mg of H2O)/g. For relative humidities ≤ 50%, when the mass
loading was recalculated on a per (H2O molecule/polymer repeat unit) basis, the fiber had a capacity of
∼0.5−1 H2O per PANI-ES repeat unit. In this same range of humidities, the apparent diffusion coefficients
varied between 0.21 and 0.67 × 10-12 m2/s, except for the case of desorption at 80% RH, wherein a value
of 2.38 × 10-12 m2/s was obtained. In general, the apparent diffusion coefficients were always larger during
desorption than during adsorption. The water capacity of the polyaniline hollow fibers is at the upper end of
what is usually observed for glassy polymers and provides the possibility for exploiting their electronic
conductivity, good mechanical strength properties, and desiccant qualities for advanced humidity control and
sensing applications.
This paper studied the radiation hardness of low gain avalanche detector (LGAD) developed by the Novel Device Laboratory (NDL) in Beijing and the Institute of High Energy Physics (IHEP) of Chinese Academy of Sciences, in the context of an upgrade project of the ATLAS detector for the high luminosity phase of LHC. NDL LGAD sensors with di↵erent layouts, epitaxial resistivity, doping profile were irradiated up to 1.02 ⇥10 15 n eq /cm 2 by 70 MeV proton at Cyclotron and Radioisotope Center (CYRIC). The timing resolution of NDL LGAD sensors reached 50 picoseconds (ps) and the collected charge reached 3-4 Femtocoulombs (fC) after irradiation.
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