Comparison of different methods for estimating TMRad from dynamic DSC measurements with ADT 24 values obtained from adiabatic Dewar experiments

Recently, a method for estimating the time to maximum rate under adiabatic conditions (TMRad) from non-isothermal DSC measurements was presented by Ke ller, A., Stark, D., Fierz, H., Heinzle, E., & Hungerbuhler, K. (1997). J. Loss. Prev. Process. Ind., 10, 31-41. The method was tested on the basis of isoperibolic data only, because data from adiabatic experiments were not a vailable. In this study we used results from 180 Dewar vessel experiments w ith an adiabatic shield and the corresponding dynamic DSC measurements prov ided by Aventis Research and Technologies (former Hoechst AG) to test the e stimation method suggested. The data were obtained for reaction mixtures, b ottom residuals, reaction residuals, and products. We found that in all cas es the predicted TMRad at a given temperature was shorter than the experime ntal value determined from adiabatic measurements. This result shows that t he TMRad estimation method is useful as a screening tool for the assessment of thermal risk. Furthermore, the estimation method introduced by Keller e t al., is more on the safe side than other common and often applied estimat ion methods like the so-called 100 degree rule or the 50 degree rule. We al so describe how to derive adiabatic induction times for different temperatu res by using a minimum number of adiabatic experiments. (C) 1999 Elsevier S cience Ltd. All rights reserved.