Rate of weight loss

Fig. 17. Cavitation phenomenon in pumps showing cavitation bubble distribution and rate of weight loss as a function of cavitation coefficient at constant...

Corrosion Rate the rate at which a corrosion reaction proceeds. It may be expressed as a rate of penetration mm y", /xm s etc. (inches per year or ipy is still sometimes used), or as a rate of weight loss per unit area, for example g m" d", mg dm d (mdd) etc. It may also be expressed as the equivalent current density. 

The importance of MIC has been underestimated, because most MIC occurs as a localized, pitting-type attack. In general this corrosion type results in relatively low rates of weight loss, changes in electrical resistance, and changes in total area affected. This makes MIC difficult to detect and to quantify using traditional methods of corrosion monitoring [1447]. 

We measure the permeation rate of liquids through bottles by filling them with the liquid of interest and placing them in a controlled atmosphere chamber. At intervals we remove the bottles, weigh them and return them to the chamber. We repeat this procedure over a period of days, or even weeks, until their rate of weight loss reaches a steady value. We calculate the permeability factor from Eq. 8.10. 

Figure 7 TGA data for a rigid PVC compound showing % weight loss and derivative (rate of) weight loss traces.

In the absence of any inorganic additive, the resin loses about 80% of its weight during the initial decomposition stage, this corresponding to the loss of styrene and HBr, Q3) followed by char oxidation (13-7% loss) at a DTG max (temperature of maximum rate of weight loss) of ca. 528°C. 

Table I. Comparison of Cellulose Pyrolysis Rates (Rates of Weight Loss) Rnalyzed by Differential Methods for Control...

Table II. Activation Parameters for Pyrolysis (Rate of Weight Loss) for Untreated Cellulose Samples Based on Data in Table I...

Prepolymer samples were spin-coated onto silicon wafers and fully cured. The cured polymer films were removed from the wafer and tested by TGA. Analyses were carried out to measure the rate of weight loss at various temperatures in air and in nitrogen. From these results the time to a 1% weight loss was determined and these results are depicted graphically in Figure 3.7. 

The rate of weight loss for the thermal decomposition in an inert atmosphere was found to follow the simple rate expression ... 

The thermal behavior of the hyperbranched polymer 7, as well as that of the related tetra- and octanuclear dendrimers 1 and 2, was examined by thermal gravimetric analysis (TGA) and derivative thermogravimetry (DTG). The samples were heated at a ramp rate of 10 °Cymin under nitrogen atmosphere in the tenqierature range 25-8(K) °C. The major decompositions occur between 340 and 540 °C for the tetranuclear 1, and between 370 and 520 °C for the octanuclear 2, whereas for polymer 7 a faster rate of weight loss is observed at a higher (480 and 560 C) temperature range. The thermal stability of the network dendrimeric material 7 is... 

The rate of weight loss of polymer A was determined in vacuum and in air. The activation energy of degradation in vacuum calculated from this... 

The influence of mechanical strain and structural stress on the rate of weight loss and the decrease in DP in acid hydrolysis is in agreement with some considerations of Elema (17), who discussed the role of structural stresses in connection with weak links in the cellulose chain. It may be mentioned here, however, that our results on heterogeneous acid hydrolysis did not yield further evidence of these weak links. ... 

Temperature of onset of degradation, as indicated by IR spectroscopy. Temperature of maximum rate of weight loss from TGA. 

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