The stability of live-attenuated viruses is very challenging due to thermal sensitivity; therefore, solid form is usually required (often freeze-dried products). Micropellet technology is a lyophilization technology that has the potential to provide greater flexibility in the presentation of a given vaccine particularly in multi-dose format or in combination of different vaccines. As a novel vaccine alternative process, this spray freeze-dried (SFD) micropellet technology was evaluated using as a model a yellow fever virus produced in Vero cells (vYF) …
Kinetic parameters of the decomposition of hazardous chemicals can be applied for the estimation of their thermal behavior under any temperature profile. Presented paper describes the application of the advanced kinetic approach for the determination of the thermal behavior also under adiabatic conditions occurring e.g. in batch reactors in case of cooling failure. The kinetics of the decomposition of different samples (different manufacturers and batches) of 3-methyl-4-nitrophenol were investigated by conventional DSC in non-isothermal (few heating rates varying from 0.25 to 8.0 K/min) and isothermal (range of 200-260°C) modes …
The exothermic decomposition parameters of a single-base propellant were obtained using differential scanning calorimeter (DSC) tests conducted at various heating rates. The DSC signals were processed using the Friedman isoconversional method to compute activation energy as a function of conversion. There was excellent agreement between the experimental and the simulation plots, which confirms the validity of the kinetic model used to describe the propellant’s exothermic decomposition. The kinetic parameters and heat balance were subsequently analyzed and used for a simulation of cookoff experiments conducted at different experimental rates (heating rates 3.3 – 1.0 K/h and a heat-wait-search mode) …
An adiabatic calorimeter is very often used for the investigation of runaway of exothermic reactions. However the ideal adiabatic environment is a theoretical state which during laboratory scale testing cannot be obtained but may only be approached. Deviation from the fully adiabatic state comes from (i) the thermal inertia of the test system or heat lost into the sample container and (ii) the loss of heat from the container itself to the environment that reflects the ‘operational adiabaticity’ of the instrument…
Differential scanning calorimetry (DSC) carried out with few heating rates was applied in the studies of the thermal properties of four energetic materials: EI® propellant, high explosive PBXW-17, pyrotechnic mixtures with composition B/KNO3 (50:50) and B/KNO3 (30:70). DSC signals, after optimization of the baseline, were used for the calculation of the kinetic parameters (KP) of the decomposition process applying advanced kinetic software designed by AKTS. The determination of the kinetic parameters was based on the differential iso-conversional method of Friedman. The correctness of the estimation of KP was checked by the comparison of the experimental and predicted courses of the decomposition …
An advanced study on the thermal behaviour of double base (boost and sustain propellant) rocket motor used in a ground to air missile has been carried out by differential scanning calorimetry (DSC). The presence of two propellants as well as the different experimental conditions (open vs. closed crucibles) influence the relative thermal stability of the energetic materials. Several methods have been presented for predictions of the reaction progress of exothermic reactions under adiabatic conditions. However, because decomposition reactions usually have a multi-step nature, the accurate determination of the kinetic characteristics strongly influences the ability to correctly describe the progress of the reaction …
Using a computational method (AKTS-TA-Software) for solid-state kinetic analysis, the calculations of the progress of solid-state reactions were achieved employing temperature conditions different from those at which the experiments were carried out. The prediction of the solid-state reaction extent is illustrated by the results obtained during decomposition of hydromagnesite (component of some pharmaceuticals) …
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