Thermal analysis water content measurement

Thermal Analysis. The water contents of CPA and zeolite were measured by thermogravimetric analysis (TGA). Differential thermal analyses (DTA) were done for comparison. The instrument used was a Du Pont 900 with a TGA attachment. 

Thermal analysis (DTA) was performed both on the dried unreacted gel and on the product crystals to determine water and TPA content. Measurements were made using a NETZSCH Model STA 409 thermogravimetric analyzer. Samples were scanned from 30 to 700C at a rate of lOC/min. under a lOml/min. flow of dry nitrogen. Details of the experimental protocol are listed elsewhere (21). 

It is also recommended that the experimenter thoroughly analyze what is being collected to ensure the necessary data will be available for the analysis that will be done. For example, if the thermal efficiency of a combustion process will be calculated, the experimenter needs to measure both the composition and the temperature of the exhaust products, among other variables such as the fuel flow rate and composition, the combustion air flow rate, the furnace pressure, and the furnace skin temperature. If the actual water content in the exhaust products is not measured, which is often the case, it can be calculated knowing the other components in the stream and the fuel composifion and flow rate. The furnace air leakage can be calculated based on the flue gas composition and combustion air flow rate. The point is that the experimenter should carefully check... 

Various methods for measuring bound water content have been proposed (see Lee and Lee [179], and references therein). A considerable amount of work on the properties of interfacial water of organized assemblies has been done with probes or reactions whose rates are sensitive to the microenvironment [250-252]. These methods often involve hydrophobic solutes whose (average) solubilization site in the micellar pseudophase is stiU a matter of discussion, and which may perturb the aggregate structure [253,254], This is not the case in thermal analysis. 

Around lOOX, thermal analysis measurements with open cracibles distinguish among adsorbed, absorbed, and crystal water. Thus, DSC curves, TG curves, or microwave dielectric measurements give information on water content or on the... 

The bound water content can be determined by methods such as dilatometric determination, vacuum filtration, expression, drying, and thermal analysis. The dilatometric method is based on the assumption that free water can be frozen at 20°C. By placing a known amount of sludge into a scaled container called a dilatometer and measuring the volume of expansion at 20°C, the free water content can be calculated [18]. The part that does not freeze is the bound water. The sludge is usually mixed with a fluid that does not freeze at 20°C, is immiscible with water, has specific gravity less than 1.0, and shows... 

In this chapter, first, the individual thermal and mechanical properties of chitosan and PVA as-cast films were investigated for as-cast films containing water and perfectly dried films in relation to molecular mobility of PVA chains by using x-ray, DSC, positron annihilation, and viscoelastic measurements. Based on the results, the detailed characteristics of the blends were analyzed as a function of chitosan content in terms of the individual properties of chitosan and PVA. Further analysis of the blend films was carried out for chitosan content on the film surface of drawn films by electron spectroscopy for chemical analysis (ESCA) and water-contact angle experiments. 

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