Dynamic sorption apparatus

Figure 1. Schematic of dynamic sorption apparatus and recording system.

The dynamic sorption apparatus clearly demonstrates the advantages of performing dynamic rather than static measurements of spreading and penetration at microscopic resolutions on substrates as complex as paper. The ability to observe ink or toner/paper interactions in situ should be especially valuable for investigating other non-impact technologies. 

The author is grateful for the assistance of R. Forsyth with the dynamic sorption apparatus, A. Jones for physical test data and Xerox Corporation for granting permission to publish this article. Thanks are also due to Dr. M.B. Lyne (PAPRICAN) for providing Bristow absorption data. 

The water-sorption experiments were carried out in a dynamic flow vapor sorption apparatus (Model SGA100, VTI Corporation, Hialeah, FL). Samples of the two polymorphs were placed in the instrument s sample chamber and their moisture uptake as a function of relative humidity (RH) was measured. Water-sorption isotherms for both polymorphs were carried out imder the temperature conditions of 20, 25, 35, and 45°C. The amoimt of sample used for an analysis depends on the sample s tendency to pick up water. If the sample is highly hygroscopic, about 2-5 mg is sufficient for the test, but if the sample is nonhygroscopic, a larger mass is needed, about 25 mg or more. For this study, water-sorption isotherms for both polymorphs were carried out using the flow system and a sample size of about 50 mg. 

Figure 4.4.7b. Dynamic isopiesl-ic vapor-sorption apparatus using a quartz spring (drawing provided by G. Sadowski) a) evaporator, b) superheater, c) measuring cell, d) condenser, e) quartz spring, f) polymer sam-ple/solution, g) Pt-100 resistance thermometer. [Reprinted with permission from Ref. 87, Copyright 1995, Wiley-VCH].

Solubility data of nimesulide, which are essential when supercritical sorption is studied, were determined in a previous work by using a dynamic apparatus [10],... 

A gravimetric technique to study the sorption, desorption, and diffusion characteristics of uxiter vapor in excised skin under dynamic conditions is described. The technique features a continuously recording microbalance and a humiditygenerating apparatus which provides a stream of air with any given relative humidity. The diffusion coefficient is determined from the kinetics of sorption and desorption. The technique can be used to study other polymeric films, fibers, and powders. 

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