Normalized mass loss

Predicted, Normalized Mass Loss vs. Time for Various Values of. [ ] = [day ] Q - grams of Glass... 

Leach test results were calculated in terms of normalized mass loss of the glass (mass loss/unit area) based on l Cs, 90gr> or 238pu, The appropriate equation is ... 

The total normalized mass loss was then determined by summing the mass losses over all the previous time increments. These tests were performed so that both short and long term data could be obtained with the same sample of glass. 

Figure 1 Time dependence of normalized mass losses in deionized water at 40°C based on Cs-137, Sr-90, and Pu-238 from SRP borosilicate glass containing actual radioactive waste. 0, MCC-1 tests , tests where leachant was replaced periodically. Error bars indicate the precision of duplicate tests.

Leachant Time, days SA/V cm l Normalized Mass Loss, g/m2... 

T 40°C, results for normalized mass losses are given in Table IV. Compositions are listed in Table II. 

A in the normal Arrhenius equation. Note that k is the rate constant at T. The algorithm was used to fit kinetic constants to the pyrolysis of wheat straw at 5,10 and 40°C/min (one data set per heating rate). The algorithm use the local temperature and does not rely on a constant heating rate. The data from an experiment were converted to dry ash free basis and the mass loss rate was normalized by the maximum mass loss rate. The data in the range where the normalized mass loss rate was above 0.1 was then used. This excludes the lignin tail from the data. The mass data were then converted to degree of conversion and normalized so the conversion of the final data point was 1.300 points were used per data set. Kinetic parameters were fitted to the individual data sets as well as to all three data sets simultaneously, The kinetic values are listed in Table 1. 

Since the usual decomposition temperatures obtained from TG are highly dependent on the experimental procedure employed, Doyle (43) has used the expression procedural decomposition temperature as a precaution against mistakenly regarding such trivial data as definitive. Two types of procedural decomposition temperatures were defined by Doyle (43). The first of these was called the differential procedural decomposition temperature (dpdtl which was used to define the location of knees in normalized TG curves. The second type was called integral procedural decomposition temperature (ipdt) and was a means of summing up the entire shape of the normalized mass-loss curve. 

Figure 5.18 Relationship between normalized mass loss (NML) of CH (in kgm ) and concentration of Cr in the cement mix (in mgl" ) and composition of matrix cement...

Mass loss determinations refer to the total change resulting from reactant decomposition and usually include contributions from a mixture of product compounds, some of which would normally be condensed under conditions used for accumulatory pressure measurements. Such information concerned with the overall process is, however, often usefully supplemented by evolved gas analyses (EGA) using appropriate analytical methods. Sestak [130] has made a detailed investigation of the effects of size and shape of reactant container on decomposition kinetics and has recommended that the sample be spread as a thin layer on the surfaces of a multiple plate holder. The catalytic activity of platinum as a reactant support may modify [131] the apparent kinetic behaviour. 

The techniques referred to above (Sects. 1—3) may be operated for a sample heated in a constant temperature environment or under conditions of programmed temperature change. Very similar equipment can often be used differences normally reside in the temperature control of the reactant cell. Non-isothermal measurements of mass loss are termed thermogravimetry (TG), absorption or evolution of heat is differential scanning calorimetry (DSC), and measurement of the temperature difference between the sample and an inert reference substance is termed differential thermal analysis (DTA). These techniques can be used singly [33,76,174] or in combination and may include provision for EGA. Applications of non-isothermal measurements have ranged from the rapid qualitative estimation of reaction temperature to the quantitative determination of kinetic parameters [175—177]. The evaluation of kinetic parameters from non-isothermal data is dealt with in detail in Chap. 3.6. 

Tables I, III, V, and VII give the kinetic mass loss rate constants. Tables II, IV, VI, and VIII present the activation parameters. In addition to the activation parameters, the rates were normalized to 300°C by the Arrhenius equation in order to eliminate any temperature effects. Table IX shows the char/residue (Mr), as measured at 550°C under N2.

This parameter, the smoke parameter, is based on continuous mass loss measurements, since the specific extinction area is a function of the mass loss rate. A normal OSU calorimeter cannot, thus, be used to measure smoke parameter. An alternative approach is to determine similar properties, based on the same concept, but using variables which can be measured in isolation from the sample mass. The product of the specific extinction area by the mass loss rate per unit area is the rate of smoke release. A smoke factor (SmkFct) can thus be defined as the product of the total smoke released (time integral of the rate of smoke release) by the maximum rate of heat release [19], In order to test the validity of this magnitude, it is important to verify its correlation with the smoke parameter measured in the Cone calorimeter. 

The alteration of several titanate ceramics in pure water at 90 °C has been investigated by Leturcq et al. (2001). These experiments were performed under conditions of high surface area to volume ratio and lasted for over one year without replacement of the solution. Starting materials included melted Synroc-like materials and hot pressed Synroc-C. This study reported the normalized elemental mass losses, defined by the equation ... 

Plot data with the mass loss normalized to 100% on the ordinate axis and temperature on the abscissa. 

An additional transformation may be used to convert the (r coordinate to a normalized stream function , which facilitates treatment of mass loss or gain at the boundaries such as can occur at a chemically reacting surface. The normalized stream function is defined as... 

Moreover if we apply equation (2) to the deep interior of stars (r=0), eather the velocity or the density should become infinitely large at r=0. Therefore we cannot get any normal stellar structures. This means that equation (2) is inadequate to the interior part of stars. This difficulty comes from the steady-state approximation (1). The mass flux must reduce zero at the center of the stars or the surface of the degenerate stars. The interior flow therefore should be described by another steady states, not by equation (1). Therefore we will present a new steady-state approximation and derive mass-loss equations which is available also to the deep interior of stars. 

---