Water testing absorption

The moisture content of a plastic affects such conditions as electrical insulation resistance, dielectric losses, mechanical properties, dimensions, and appearances. The effect on the properties due to moisture content depends largely on the type of exposure (by immersion in water or by exposure to high humidity), the shape of the product, and the inherent behavior properties of the plastic material. The ultimate proof for tolerance of moisture in a product has to be a product test under extreme conditions of usage in which critical dimensions and needed properties are verified. Plastics with very low water-moisture absorption rates tend to have better dimensional stability. 

BS 903-18, Physical testing of rubber. Determination of equilibrium water vapour absorption, 1973. 

The standard states that the measured equilibrium water vapour absorption is substantially the same as the equilibrium absorption which would be obtained by immersion in an aqueous solution and which would be in equilibrium with the vapour (apart from effects due to extraction of water soluble constituents), i.e. in a solution which would maintain the test humidity. As this implies, the equilibrium water absorption of rubber is reduced if the water is not pure and this test method, because 100% R.H. is not readily maintained, does not measure the absorption of pure water. When approaching 100% R.H. the effect is rapid and even very small amounts of a salt in solution will significantly lower the equilibrium absorption. Hence, tests intended to simulate the use of rubber in contact with an aqueous solution, rather than pure water, should be made with that solution or with one having the same equivalent relative humidity. 

Hancock, B. C. and G. Zogra. 1993. The use of solution theories for predicting water vapor absorption by amorphous pharmaceutical solids a test of the Flory-Huggins and Vrentas rriddefso. Res.10 1262-1267. 

Rubber, vulcanized Determination of the effect of liquids Standard test method for rubber property-effect of liquids Standard test method for rubber property Change in length during liquid immersion Determination of the behavior of rubbers and elastomers when exposed to fluids and vapors Determination of the effect of liquids Determination of equilibrium water vapor absorption... 

Water quality projects such as those described below have been shown to be effective methods for engaging students in environmental chemistry courses for majors (Juhl et al. 1997) and for nonscience majors (Lunsford et al. 2007). When the water quality research projects were conducted, Chemistry and the Environment was linked to a world geography course as part of a learning community. Poor water quality and access to potable water were a global environmental theme for both courses. Consequently, the chemistry research projects focused primarily on water analysis. Field water testing kits, atomic absorption spectroscopy, and fluorescence methods (typically for biological con-... 

Another typical source of uncertainty in mixture assessment is the potential interaction between substances. Interactions may occur in the environment (e.g., precipitation after emission in water), during absorption, transportation, and transformation in the organism, or at the site of toxic action. Interactions can be either direct, for example, a chemical reaction between 2 or more mixture components, or indirect, for example, if 1 mixture component blocks an enzyme that metabolizes another mixture component (see Chapters 1 and 2). Direct interactions between mixture components are relatively easy to predict based on physical-chemical data, but prediction of indirect interactions is much more difficult because it requires detailed information about the processes involved in the toxic mechanisms of action. One of the main challenges in mixture risk assessment is the development of a method to predict mixture interactions. A first step toward such a method could be the setup of a database, which contains the results of mixture toxicity tests. Provided such a database would contain sufficient data, it could be used to predict the likelihood and magnitude of potential interaction effects, that is, deviations for CA and RA. This information could subsequently be used to decide whether application of an extra safety factor for potential interaction effects is warranted, and to determine the size of such a factor. The mixture toxicity database could also support the search for predictive parameters of interaction effects, for example, determine which modes of action are involved in typical interactions. 

Figure 24.14 The left panel is a plan of the testing area near the LENS (reflected shock) tunnel 1 — 8 test section 2 — TDL probe 3 — 4 nozzle M = 8-16 4 — 8" reflected shock tube 5 — fiber optic and signal line conduit 6 — data acquisition and 7 — TDL system optical table. The right panel is a schematic diagram of the setup used to record water-vapor absorption in high-enthalpy flows 1 — InGaAs detectors 2 — tunable diode laser Ai = 1400.74 nm 3 — ring interferometer 4 — tunable diode laser A2 = 1395.69 nm and 5 — HoO reference cell...

Effects of System Physical Properties on kG and kL When designing packed towers for nonreacting gas-absorption systems for which no experimental data are available, it is necessary to make corrections for differences in composition between the existing test data and the system in question. The ammonia-water test data (see Table 5-24-B) can be used to estimate HG, and the oxygen desorption data (see Table 5-24-A) can be used to estimate HL. The method for doing this is illustrated in Table 5-24-E. There is some conflict on whether the value of the exponent for the Schmidt number is 0.5 or 2/3 [Yadav and Sharma, Chem. Eng. Sci. 34, 1423 (1979)]. Despite this disagreement, this method is extremely useful, especially for absorption and stripping systems. 

In a research paper, six kinds of CDs including a-CD, ]3-CD, HP- -CD, RM-/3-CD, low methylated-/3-CD (Me-/3-CD) and a sulfobutyl-ether-)8-CD (SBE-]3-CD) were compared and evaluated in the effectiveness and the regeneration with toluene as the target hydrophobic VOC [84]. The results showed that all CD derivatives tested were able to decrease the volatility up to 95% depending on both of CD species and concentration. The absorption capability of -CD is 250 times larger than water. The absorption efficiency is not totally correlated with static experiments, suggesting that, besides absorption constants and stability of inclusion compounds, toluene diffusion into such CD solutions is an important factor. 

A wicking test is used to determine the absorptive velocity of water in fabrics. It is known as the capillary rise test (DIN EN 53924). With respect to time, the capillary rise of absorptive fabrics in the warp and weft directions is measured by dipping them in distilled water. The absorptive velocity depends on the capillary force, which determines the transport of liquid contrary to gravity. For fabric the wicking velocity, the path of liquid distribution and the final wet figure can be different in the warp and weft directions. 

FI. Laboratory tests are being made prior to the design of an absorption column to absorb bromine (Br2) from air into water. Tests were made in a laboratory-packed column that is 0.1524 m in diameter, has 1.524 m of packing, and is packed with saddles. The column was operated at 20 °C and 5 atm total pressure, and the following data were obtained ... 

Litmus solution in the tube became red, and the air was diminished on sparking, conformably to what was observed by Dr. Priestley , but with lime water no cloudiness was observed, although the air was diminished by one-third, and hence no fixed air was produced. With oxygen in the tube there was only a very slight diminution and the litmus was bleached (probably owing to the formation of ozone). After sparking over litmus, fixed air was formed, as shown by the lime water test. With soap-lees (caustic potash solution) in the tube the absorption in the case of air was more rapid than with water. 

The PDMS samples under test were 375 and 960 pm thick sheets. Reference and sample measurements were conducted at room temperature with a nitrogen-purged chamber to avoid water vapor absorption Hnes. The index of refraction and the absorption coefficient for both thicknesses were determined with similar characteristics obtained. The refractive index and absorption coefficient for the 960-pm-thick PDMS sheet in the terahertz region are shown in Figure 14.16. The absorption coefficient of 20 cm at 1.0 THz compares well with that of 30 cm for polyimide [8]. Using these results, the dielectric constant and loss tangent... 

PIB was chosen because water vapor absorption is very poor into this apolar, hydrophobic material. Water was stucUed as the test vapor because from prior experience it had showed the worst anomalous responses and its polar and hydrogen-bond properties would favour interfacial adsorption at polar silica and alumina sites. The design of the experiments was specifically intended to be a worst case scenario for vapor absorption in the polymo film and a best case scenario for vapor adsorption at the SAW device surface olymer interface. This arrangement tests the SAW device in the most favourable environment for evaluating interfacial effects. The results and inq>lications for SAW device fabricati[Pg.285]

Bromine. Slip the glass cover of a jar momentarily aside, add 2-3 ml. of bromine water, replace the cover and shake the contents of the jar vigorously. Note that the bromine is absorbed only very slowly, in marked contrast to the rapid absorption by ethylene. This slow reaction with bromine water is also in marked contrast to the action of chlorine water, which unites with acetylene with explosive violence. (Therefore do not attempt this test with chlorine or chlorine water.)... 

More recently, test products were created of a blend of PMMA with a phenyl-substituted methacrylate these products have a glass-transition temperature of around 125°C, a significantly reduced water absorption compared to pure PMMA of about 0.32%, but also a higher birefringence (a stress-optic coefficient of 5.2 X 10 , compared with 0.3 X 10 for PMMA and 6.8 x 10 for BPA-PC). 

The homogeneous reactor experiment-2 (HRE-2) was tested as a power-breeder in the late 1950s. The core contained highly enriched uranyl sulfate in heavy water and the reflector contained a slurry of thorium oxide [1314-20-1J, Th02, in D2O. The reactor thus produced fissile uranium-233 by absorption of neutrons in thorium-232 [7440-29-1J, the essentially stable single isotope of thorium. Local deposits of uranium caused reactivity excursions and intense sources of heat that melted holes in the container (18), and the project was terrninated. 

Analytical and Test Methods. Ash in isophthahc acid refers to the residue left after combustion of the sample. Ash consists of oxides of trace metals that are deterrnined individually by atomic absorption or inductively coupled plasma. A Kad Fischer titration is specific for the water content. 

The principal impurity in potassium metal is sodium. Potassium s purity can be accurately deterrnined by a melting point test (Fig. 2) or atomic absorption if necessary after quenching with alcohol and water. Traces of nonmetallic impurities such as oxygen, carbon, and hydrogen can be deterrnined by various chemical and physical methods (7,8). 

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