Specimen chamber 3D illustration. The specimen chamber includes the following components: (1) RH chamber, (2) sample mount, (3) door, (4) sample clamp, (5) window frames, (6) y-direction motor mount for vertical displacement, (7) insulator, (8) strain relief, (9) insulator for strain relief, (10) cooling loops, and (11) beryllium (Be) window. Key features of this new design include large escape angle (x-ray scattering angle 2θ = ±30°, horizontal), compatibility with an evacuated x-ray chamber, capability to hold multiple samples, dynamic control of temperature and relative humidity, and computer control of temperature and relative humidity integrated with data collection.
Process control instrumentation flow diagram. Here, water recirculating bath temperature, bottle temperature, HT1 and HT2, and gas flow rates are the controlled variables. The system incorporates four continuous process controls and two manipulated variables. The control loop feedback mechanism regulates the saturation level of the gas by controlling the dry and saturated gas inlet flows using Eq. (1).
Measured temperature (a) and relative humidity (b) for the EC when the temperature is set to 30 °C and the relative humidity is changes stepwise. The measured temperature is controlled to a precision of ± 0.05 °C. The standard deviation of the %RH is reported in part b and is 0.4–1.41% RH.
Measured temperature (a) and relative humidity (b) for the EC when the temperature is set to 80 °C and the relative humidity is changes stepwise. The measured temperature is controlled to a precision of ± 0.38 °C. The standard deviation of the %RH is reported in part b and is 1.25–3.18% RH.
X-ray scattering through the environmental chamber without a sample as a function of relative humidity at 60 °C. Attenuation due to Be windows, nitrogen and water molecules is minimal.
Chemical structures for (a) Nafion® polymer and (b) poly(1-[(2-methacryloyloxy)ethyl]-3-butlyimidazolium-hydroxide) (poly(MEBIM-OH)).
2D x-ray scattering pattern (at 86% RH, 25 °C) of (a) Nafion® cast film and (b) Nafion® nanofiber (arrow indicating longitude direction of fibers).20 X-ray scattering profile as a function of relative humidity for (c) Nafion® cast film and (d) Nafion® nanofibers. The x-ray scattering data are shifted vertically for clarity.
X-ray scattering profile as a function of relative humidity for a polymerized ionic liquid. The x-ray scattering profiles are shifted vertically for clarity.
Environmental chamber (EC) descriptions and capabilities.
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