Water uptake measurement

This type of water uptake measurement is very general in application. It is applicable to most porous media, where moisture transport properties need to be measured. 

We present the results of water uptake measurements in Figure 1. 

The data of Table II also indicate that for a given PcFe content the crystallite size is greater on the activated carbon. This result however does not mean that the actual particle size of PcFe is greater on the activated carbon. As will be shown below, the particles of PcFe may contain several crystallites. The mean crystallite diameter 3g calculated from the (100) reflexion is compared to the mean particle size dg determined from the water uptake measurements in Figure 4 for both carbon substrates. It appears that 3fi and 3s are in fairly good agreement in the case of the heterogeneous carbon... 

After eight years of exposure, an extensive examination was started in 1994 to evaluate the effectivity and durability of the water repellent treatments [4]. Macroscopic tests as water uptake measurements were carried out to determine the remaining effect of the protective organosilicon layer. Due to the fact that surface information from hydrophobic treatment of mineral surfaces is supplied by surface sensitive measuring techniques, TOF-SIMS and additional DRJFT-studies on treated and exposed material were performed. 

Water Uptake Measurements. The water absorption capability of films was determined by measurements of water rising by capillary action. The experimental device, also called Baumann apparatus is shown in Figure 1. The samples were cut in order to expose their inner structure to water rising. They were then coated on each of their faces (except the contact surface) with epoxide resin to prevent their swelling and put on fritted glass in contact with distilled water. The absorbed water volume versus time data is then recorded as water penetrates into the sample. 

Calculations with the water uptake measurements illustrated in Fig. 13 have shown that the stoichiometric ratio between the mixed extractant and water is 1 1, so the first step of the sequence of reactions may be assumed to be the formation of alkylammonium 2-ethylhexanoate monohydrate ... 

There are a number of techniques that can be used to measure the degree of hydrophobicity of a surface. Direct techniques such as water uptake measurements and sessile drop contact angles are often supplemented with spectroscopic studies using FTIR and NMR to provide evidence of structural groups present in aerogel samples and to quantitate the relative number of those groups. These methods are described below. 

In a similar study, Brewis et al prepared sandwiches of a nylon-epoxy adhesive between aluminum adherends and exposed them to water vapor labeled with tritium for up to 6 weeks at 50°C. The bonds were then cut into small rectangular sections and the fractional water uptake measured by liquid scintillation counting. The values were compared with those calculated for diffusion and were found to agree well for the outer pieces. For the inner pieces the measured uptake was less than the predicted value. The adhesive contained a carrier and the results seem to imply that this hinders the passage of water into the adhesive bond. These results show... 

For surface tension, contact angle and water uptake measurements thin-film samples were prepared from coating polymers with surfactant addition. Aqueous solutions of different surfactants were also studied. Coated particle samples were prepared for drug release studies. The surface characteristics of some active ingredients in compressed form were monitored. 

Three examples of the use of EIS will be given next atmospheric water uptake, measurements during delamination of intact and perforated coatings, and measurement of reproducible laser defects. 

The water uptake measurement method (proposal) (in the proposal, the words superabsorbent resin are used) for superabsorbent polymers is thus organized as follows [152] ... 

Remarks A similar expression as for the water uptake measurement method is used for the water uptake, particle size, and reference specifications of superabsorbent polymers. 

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