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) …
The new precision machine gun in development at company Diehl uses a propellant charge without any case. It is based on consolidated NC double base ball powder. For ballistic reasons a defined distance between propellant charge body (PB) and the wall of the combustion chamber must be adjusted and for this a new feature was developed in cooperation with Fraunhofer ICT. The distance is achieved with foam stripes based on polyurethane energized by HMX. To avoid a degradation of the ballistic properties during use time, compatibility investigations using heat flow microcalorimetry have been performed to select suitable foam formulations. For this special assessment the criteria have been developed …
Current legislation about goods carriage (ADR – Agreement Concerning the International Carriage of Dangerous Goods by Road) sets the determination of several parameters related to the conditions of the used containers. Several of these parameters are required for the substance classification and the definition of the precautions to be adopted during transportation. One of the main potential hazards during freight is related to the thermal decomposition of the substance. Testing for the identification of decomposition in the carriage conditions can be time consuming and expensive, therefore different solutions have been attempted to simulate thermal behaviour of chemical compounds during transportation …
When determining Self Accelerating Decomposition Temperatures (SADT) for shipment purposes, the kinetics of the decomposition reaction of the materials must be known. The simplified models assuming the first order decomposition kinetics are generally applied, however this traditional approach fails in correct SADT determination for autocatalytic and multistage overlapped reactions. For these cases a more universal, yet easily implemented, advanced method will be presented in which the detailed kinetic mechanism does not need to be known to correctly predict SADT …
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) …
Two small calibre and four medium calibre types of propellants were investigated non-isothermally (0.25-4 K min-1) by differential scanning calorimetry (DSC) in the range of RT-260-C and isothermally (60-100°C) by heat flow calorimetry (HFC). The data obtained from both techniques were used for the calculation and comparison of the kinetic parameters of the decomposition process. The application of HFC allowed to determine the kinetic parameters of the very early stage of the reaction (reaction progress below 0.02) what, in turn, made possible the precise prediction of the reaction progress under temperature mode corresponding to real atmospheric changes according to STANAG 2895 …
Present study depicts the extension of the method of the application of the advanced kinetic description of the energetic materials decomposition by its combination with the exact heat balance carried out by numerical analysis and the determination of the Self-Accelerating Decomposition Temperature (SADT). Moreover, the additional parameters such as thermal conductivity of the self-reactive substances, the type of containers and insulation layers, and different temperature profiles of the surrounding environment were taken into consideration …
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…
The hyphenated thermal analysis-mass spectrometry technique (TA-MS) was applied for the investigation of the thermal behavior of reference and aged parchment samples. The kinetic parameters of the process were calculated independently from all recorded TA and MS signals. The kinetic analysis showed the distinct dependence of the activation energy on the reaction progress. Such behavior is characteristic for the multistage mechanism of the reaction …
Part A of this series of papers (Parts B to E follow) presents the data and methods used, as well as the results obtained by participants in the ICTAC Kinetics Project. The isothermal and non-isothermal data sets provided were based on a hypothetical simulated process as well as on some actual experimental results for the thermal decompositions of ammonium perchlorate and calcium carbonate. The participants applied a variety of computational methods. Isoconversional and multi-heating rate methods were particularly successful in correctly describing the multi-step kinetics used in the simulated data …
The influence of experimental conditions on the kinetic parameters of gas-solid reactions has been investigated using the reduction of nickel oxide by hydrogen as a model reaction. The experimental parameter studied were heating rate, sample mass, total gas flow and hydrogen concentration. For arbitrarily chosen “standard conditions” the kinetic parameters best describing the course of the reaction were calculated using the global cruves analysis method. Experiments were carried out with different heating reates, in the range 1.3-10.6 K min-1. Twenty two kinetic models of solid-state reactions proposed in the literature were tested using numeric integration methods …
We use cookies to ensure that you have the best experience on our website. If you continue to use this site, we will assume that you are satisfied with it.Ok
