Authors:C. Gonzales, J. Sempere, D. Nomen, and S. Waldram
This paper explains why directly agitated test cells are sometimes required in order to obtain good adiabatic calorimetry data that can be used with confidence to predict large scale plant behaviour. Experiments for methyl methacrylate polymerisation are reported. Simple procedures are presented for calculating genuine thermo-kinetic parameters from data which includes energy dissipation from the stirrer drive system.
Authors:J. Sempere, R. Nomen, E. Serra, B. Sempere, and D. Guglielmi
Titanium nitride and carbide oxidation have been studied using TG and DSC. Titanium nitride shows a oxidation behavior were both techniques detect a unique phenomenon. Titanium carbide shows a variable behavior depending on the heating rate and sample size. Low masses and heating rates provide similar results to titanium nitride. However, using moderate sample sizes and scanning rates a two-stage oxidation is observed. The first step is extremely fast and exothermic, consuming the oxygen trapped inside the nanoparticle bed. The second is controlled by the diffusion of the oxygen and CO2 through the sample. Thermal safety conclusions are extracted from this observation. Energies of activation calculated using traditional kinetic models are lower than those found in the literature, being an indication of the influence of the specific surface of the material.