Mixtures properties, laboratory experiments

Experimental Materials. All the data to be presented for these illustrations was obtained from a series of polyurethane foam samples. It is not relevant for this presentation to go into too much detail regarding the exact nature of the samples. It is merely sufficient to state they were from six different formulations, prepared and physically tested for us at an industrial laboratory. After which, our laboratory compiled extensive morphological datu on these materials. The major variable in the composition of this series of foam saaqples is the aaK>unt of water added to the stoichiometric mixture. The reaction of the isocyanate with water is critical in determining the final physical properties of the bulk sample) properties that correlate with the characteristic cellular morphology. The concentration of the tin catalyst was an additional variable in the formulation, the effect of which was to influence the polymerization reaction rate. Representative data from portions of this study will illustrate our experiences of incorporating a computer with the operation of the optical microscope. 

The subscript in vessel is for the reactor or building. The subscript experimental applies to data determined in the laboratory using either the vapor or dust explosion apparatus. Equation 6-20 allows the experimental results from the dust and vapor explosion apparatus to be applied to determining the explosive behavior of materials in buildings and process vessels. This is discussed in more detail in chapter 9. The constants KG and KSt are not physical properties of the material because they are dependent on (1) the composition of the mixture, (2) the mixing within the vessel, (3) the shape of the reaction vessel, and (4) the energy of the ignition source. It is therefore necessary to run the experiments as close as possible to the actual conditions under consideration. 

You frequently use your knowledge of properties to make and separate mixtures and substances. You probably do this most often in the kitchen. Even the act of sorting clean laundry, however, depends on your ability to recognize and make use of physical properties. This activity is a "thought experiment." You will use your understanding of properties to mix and separate a variety of chemicals, all on paper. Afterward, your teacher may ask you to test your ideas, either in the laboratory or at home in the kitchen. 

Laboratory photolysis experiments were designed to confirm that 2,3,7,8-TCDD contained in the selected scrubber solvent could be reduced to 1 ng/g and to determine the reaction rates of the primary HO constituents and 2,3,7,8-TCDD in that solvent matrix. A previous photolysis process for 2,3,7,8-TCDD used hexane as a solvent (8). The solvent selected for use in the TD/UV process was different - a high boiling (kerosene-like) mixture of isoparaffins. This hydrocarbon solvent was selected because of its very low vapor pressure and water solubility, nontoxic and nonflammable characteristics, relatively low cost, chemical stability, and good solvent properties for HO constituents. A second major difference from earlier IT photolysis studies was the presence in the scrubber solution of significant concentrations of other chlorinated organic reactants (2,4-D and 2,4,5-T) which were also subject to photolysis. In fact, the typical concentration ratio between 2,4-D or... 

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