AKTS Software Technical Comments

The Simulation of the Thermal Behavior of Energetic Materials based on DSC and HFC Signals

B. Roduit1, L. Xia1, P. Folly2, B. Berger2, J. Mathieu2, A. Sarbach2, H. Andres3,
M. Ramin3 , B. Vogelsanger3, D. Spitzer4, H. Moulard4, D. Dilhan5

1 AKTS AG, TECHNOArk 1, 3960 Siders, Switzerland
2 armasuisse, Science and Technology, 3602 Thun, Switzerland
3 Nitrochemie Wimmis AG, 3752 Wimmis, Switzerland
4 ISL, Institut franco-allemand de recherches de Saint Louis, France
5 CNES Centre National d'Etudes Spatiales, 31401 Toulouse, France

Abstract

Two small calibre and four medium calibre types of propellants were investigated non-isothermally (0.254 K min1) by differential scanning calorimetry (DSC) in the range of RT-260C and isothermally (60100C) 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. In addition, the kinetic parameters obtained from DSC data enabled determination of self-accelerating decomposition temperature (SADT) and comparison of the predicted ignition temperature during slow cook-off with the experimental results. The study contains also the results of the calculation of the time to maximum rate (TMRad) of the propellants under adiabatic conditions.

View Study: Journal of Thermal Analysis and Calorimetry, Vol. 93 (2008) 1, 143-152:
http://link.springer.com/article/10.1007%2Fs10973-007-8864-3

 


 

Advanced Simulation of the Lifetime of Energetic Materials based on HFC Signals

B. Roduit1, P. Guillaume2, S. Wilker3, P. Folly4, A. Sarbach4, B. Berger4,
J. Mathieu4, M. Ramin5, B. Vogelsanger5

1 AKTS AG, TECHNOArk 1, 3960 Siders, Switzerland
2 PB Clermont SA, Rue de Clermont 176, 4480 Engis, Belgium
3 Bundeswehr Institute for Materials (WIWEB), Grosses Cent, 53913 Swisttal-Heimerzheim, Germany
4 armasuisse, Science and Technology, 3602 Thun, Switzerland
5 Nitrochemie Wimmis AG, 3752 Wimmis, Switzerland


Abstract

The prediction of the shelf life of energetic materials requires the precise determination of the kinetics of their decomposition. Due to the fact that energetic materials decompose with the evolution of heat, the thermoanalytical methods such as Differential Scanning Calorimetry (DSC) and Heat Flow Calorimetry (HFC) are often used for the monitoring the reaction rate and the evaluation of the kinetic parameters of these reactions. In the present paper we describe the precise, advanced method of the evaluation of the kinetic parameters from HFC signals. Proposed method was applied for the kinetic evaluation of the decomposition process of two spherical double base and one EI® propellants type, all for small calibre used in defence applications. The kinetic parameters were determined from the experiments carried out between 50-100°C. The very good description of the low temperature data by the kinetic parameters determined at higher temperatures indicates the constancy of the decomposition mechanism between 50 and 100°C. The experimental data collected during more than 7 years by means of HFC (at 50°C) were well simulated by the kinetic parameters derived from the high temperature HFC signals. Such a possibility enables e.g. the precise prediction of the shelf life of the energetic materials at any temperature mode in the range of 50-10°C, at different climatic categories proposed by STANAG 2895 [1] and, more generally, the precise simulation of the reaction at any temperature profile close to the ambient temperature.

View Study (pdf, 594 KB)

 


 

Prediction of the Thermal Behaviour of Energetic Materials by Advanced Kinetic Modelling of HFC and DSC Signals

Bertrand Roduit1, Patrick Folly2, Alexandre Sarbach2, Beat Berger2,
Michael Ramin3, Beat Vogelsanger3

1AKTS AG, TECHNOArk 1, 3960 Siders, Switzerland
2armasuisse, Science and Technology Centre, 3602 Thun, Switzerland
3Nitrochemie Wimmis AG, 3752 Wimmis, Switzerland


Abstract

High energetic materials can slowly decompose during storage or transport particularly at elevated temperatures which may result in reduced performance and correct functionality. Even very low decomposition progress of the exothermic reaction resulting in minor heat release can significantly change the properties of the propellants leading to shortening of the service life-time. The reaction progress influencing already the behaviour of the samples can be in the range of ca. 1-2% of the total decomposition degree. There are the literature reports showing that the amount of the evolved heat during decomposition as low as ca. 40 J/g can alter the material properties. Monitoring such a minor heat release requires very sensitive techniques as Heat Flow Calorimetry (HFC).

Proposed method for simulation of the amount of heat evolved during aging of the energetic materials which allows predicting the thermal behaviour of the samples is based on the elaboration of the difference between the HFC signals recorded for the unaged and differently altered samples. The samples aged in furnaces at 50, 60 and 70°C were investigated by HFC technique at 80°C and obtained signals were compared with the traces of the unaged sample recorded during 10 days also at 80°C. Observed changes of the recorded heat flows as a function of time at 80°C for the differently aged samples related to the heat flow of the unaged sample allowed the determination of the kinetic parameters of the decomposition process. They were determined by the differential isoconversional method applying the principle of the compensation effects widely used in the kinetics of the solid heterogeneous reactions. The knowledge of the kinetics of the early stage of the process allowed the precise prediction of the reaction rate at any temperature mode. It allowed also the simulation of arbitrarily chosen cumulative heat release (e.g. 40 J/g) at any temperature profile such as storage conditions depicted in STANAG 2895 or A1 cycles “extreme hot climate” with daily temperature fluctuations between 32 and 71°C.

The application of the proposed advanced kinetic method of the elaboration of the HFC signals significantly shortens the time of the experiments: note that the required information is gained from the HFC experiments carried out at relatively high temperature of 80°C.

View study (pdf, 497 KB)

 


 

Prediction of Thermal Stability of Fresh and Aged Parchment

B. Roduit1, M. Odlyha2

1 AKTS AG, TECHNOArk 1, 3960 Siders, Switzerland
2 Thermal Methods and Conservation Science Laboratory, School of Biological and Chemical Sciences, Birkbeck College, Malet St., London WCIE 7HX, UK



Abstract

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. The comparison of the kinetic parameters calculated from the different signals i.e. TG, DSC, MS for H2O, NO and CO2, however, indicated that they were differently dependent on the aging of the sample. For the parchment samples, the aging almost does not change the kinetics of the decomposition calculated from the DSC data: the influence of aging seems to be too negligible to be detected by these techniques. On the other hand, the much more sensitive mass spectrometric technique applied to the kinetic analysis allowed monitoring of visible changes in the thermal behavior of the parchment samples due to the aging process. The influence of aging was especially visible when the MS signals of water and nitric oxide were applied for the determination of the kinetic parameters. The applied method of the kinetic analysis allowed also the prediction of the thermal behaviour of reference and aged parchment samples under isothermal and modulated temperature conditions. Presented results have confirmed the usefulness of thermoanalytical methods for investigating behaviour of such complicated systems as leather or parchment.

View Study : Journal of Thermal Analysis and Calorimetry, Vol. 85 (2006) 1, 157-163:
http://link.springer.com/article/10.1007%2Fs10973-005-7410-4

 


 

Prediction of the Ageing of Rubber using the Chemiluminescence Approach and Isoconversional Kinetics

F. Kser1,2,3, B. Roduit3

1 ACL Instruments AG, Industriestr. 11, 3210 Kerzers, Switzerland
2 Berne University of the Arts, Fellerstr. 11, 3027 Berne, Switzerland
3 AKTS AG, TECHNOArk 1, 3960 Siders, Switzerland



Abstract

A common scepticism towards the application of many product formulations results from the fact that their long-term stability is difficult to predict. In the present study we report on a new approach of kinetic analysis of the oxidation reactions of natural rubbers with and without stabiliser in an oxygen atmosphere at moderate temperatures using CL measurements carried out on a newly-developed instrumentation. The kinetic parameters of the oxidation process, calculated from the chemiluminescences signals by means of the differential isoconversional method of Friedman, were subsequently applied for the simulation of the rubber aging under different temperature profiles. The presented results are the first stage of research by using the chemiluminescence method to measure the oxidative aging of rubber and predicting the life time of rubber items.

View Study: Journal of Thermal Analysis and Calorimetry, Vol. 93 (2008) 1, 231-237:
http://link.springer.com/article/10.1007%2Fs10973-007-8985-8

 


 

Prediction of the Progress of Solid-State Reactions under Different Tempreature Modes

B. Roduit1

1 AKTS AG, TECHNOArk 1, 3960 Siders, Switzerland





Abstract

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). The applied method was used for the prediction of the reaction progress under different temperature modes such as isothermal, non-isothermal, stepwise, adiabatic, modulated and, additionally for temperature profiles reflecting real atmospheric temperature changes. A comparison between calculated and experimental data is presented

View Study : Thermochimica Acta, Vol. 388 (2002) 1-2, 377-387:
http://www.sciencedirect.com/science/article/pii/S0040603102000527

 


 

Computational Aspects of Kinetic Analysis.
Part E: The ICTAC Kinetics Project - Numerical Techniques and Kinetics of Solid State Processes

B. Roduit1

1 AKTS AG Advanced Kinetics and Technology Solutions, http://www.akts.com, TECHNOArk 1, 3960 Siders, Switzerland


Abstract

This is Part E of a series of papers that present the kinetic results computed for a hypothetical simulated process and experimental data for the thermal decompositions of calcium carbonate and ammonium perchlorate. The results show that model-fitting techniques are successful in correctly describing the decomposition of solids when assuming multi-step kinetic models. The multi-heating rate data should be used for the kinetic calculations because the application of the single-heating rate data may fail to disclose the complexity of the process. The comparison of the kinetic parameters obtained from isothermal and non-isothermal experiments is presented and discussed. The results indicate that the proper consideration of the experimental conditions at which the reaction has been investigated should be taken into account for a correct interpretation of kinetic data of solid-gas reactions.

View Study: Thermochimica Acta, Vol. 355 (2000) 1-2, 171-180:
http://www.sciencedirect.com/science/article/pii/S0040603100004470

 


 

ICTAC Kinetics Committee Recommendations for Collecting Experimental Thermal Analysis Data for Kinetic Computations

S. Vyazovkin 1, K. Chrissafis 2, M.-L. Di Lorenzo 3, N. Koga 4, M. Pijolat 5,
B. Roduit 6, N. Sbirrazzuoli 7, J. J. Suol 8

1Department of Chemistry, University of Alabama at Birmingham, 901 S. 14th Street, Birmingham, AL 35294, USA
2Solid State Physics Department, School of Physics, Aristotle University of Thessaloniki, Macedonia, Thessaloniki 541 24, Greece
3Istituto per i Polimeri, Compositi e Biomateriali (CNR), c/o Comprensorio Olivetti, Via Campi Flegrei 34, Pozzuoli, NA 80078, Italy
4Department of Science Education, Graduate School of Education, Hiroshima University, 1-1-1 Kagamiyama, Higashi-Hiroshima 739-8524, Japan
5cole Nationale Suprieure des Mines, Laboratoire Georges Friedel, CNRS UMR 5307, Centre SPIN, Saint-tienne 42023, France
6AKTS AG, TECHNOArk 1, 3960 Siders, Switzerland
7Universit Nice Sophia Antipolis, Laboratoire de Physique de la Matire Condense, Equipe Fluides et Matriaux Complexes, CNRS UMR 7336, Parc Valrose, Nice Cedex 2 06108, France
8Departament de Fsica, Universitat de Girona, Girona, Catalonia 17071, Spain

Abstract

The present recommendations have been developed by the Kinetics Committee of the International Confederation for Thermal Analysis and Calorimetry (ICTAC). The recommendations offer guidance for obtaining kinetic data that are adequate to the actual kinetics of various processes, including thermal decomposition of inorganic solids; thermal and thermo-oxidative degradation of polymers and organics; reactions of solids with gases; polymerization and crosslinking; crystallization of polymers and inorganics; hazardous processes. The recommendations focus on kinetic measurements performed by means of thermal analysis methods such as thermogravimetry (TG) or thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and differential thermal analysis (DTA). The objective of these recommendations is to assist a non-expert with collecting adequate kinetic data by properly selecting the samples and measurement conditions.

View Study : Thermochimica Acta, Vol. 590 (2014), 1-23
http://www.sciencedirect.com/science/article/pii/S0040603114002573

 


 

Computational Aspects of Kinetic Analysis Part A: The ICTAC Kinetics Project-Data, Methods and Results

M. E. Brown 1, M. Maciejewski 2, S. Vyazovkin 3, R. Nomen 4, J. Sempere 4,
A. Burnham 5, J. Opfermann 5, R. Strey 6, H.L. Anderson 7, A. Kemmler 7,
R. Keuleers 8, J. Janssens 8, H.O. Desseyn 8, Chao-Rui Li 9, Tong B. Tang 9,
B. Roduit 10, J. Malek 11, T. Mitsuhashi 12

1Chemistry Department, Rhodes University, Grahamstown, 6140 South Africa
2Laboratory of Technical Chemistry, Swiss Federal Institute of Technology, ETH-Zentrum, Universittstrasse 6, CH-8092 Zrich, Switzerland
3Center for Thermal Analysis, Department of Chemistry, University of Utah, Salt Lake City, 315 S., 1400 E., UT 84112, USA
4Department of Chemical Engineering, Institut Quimic de Sarria, Universitat Ramon Llull, Barcelona E-08017, Spain
5Lawrence Livermore National Laboratory, University of California, P.O. Box 808, Livermore, CA 94551-9989, USA
6Netzsch Gertebau GmbH, Wittelsbacherstrasse 42, D-95100 Selb/Bavaria, Germany
7Institut fr Physikalische Chemie, Soldtmannstrasse 23, D-17489 Greifswald, Germany
8Department of Chemistry, University of Antwerp-RUCA, Groenenborgerlaan 171, B 2020 Antwerpen, Belgium
9Physics Department, H.K. Baptist University, Kowloon Tong, Kowloon, Hong Kong
10AKTS AG, TECHNOArk 1, 3960 Siders, Switzerland
11Joint Laboratory of Solid State Chemistry, Academy of Sciences of the Czech Republic and University of Pardubice, Studenstka 84, Pardubice 532 10, Czech Republic
12National Institute for Research in Inorganic Materials, Science and Technology Agency of Japan, Namiki 1-1, Tsukuba, Ibaraki 305, Japan

Abstract

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 multiheating rate methods were particularly successful in correctly describing the multi-step kinetics used in the simulated data. Reasonably consistent kinetic results were obtained for isothermal and non-isothermal data. There is, of course, no `true' answer for the kinetic parameters of the real data, so the ndings of the participants are compared. An attempt has been made to forecast the tendencies for the future development of solid state kinetics.

View Study : Thermochimica Acta, Vol. 355 (2000) 1-2, 125-143
http://www.sciencedirect.com/science/article/pii/S0040603100004433

 


 

Influence of Mass Transfer on Interaction between Thermoanalytical and Mass Spectrometric Curves measured in Combined Thermoanalyser-Mass Spectrometer Systems

B. Roduit a, J. Baldyga b, M. Maciejewski a, A. Baiker a

a Department of Chemical Engineering and Industrial Chemistry, Swiss Federal Institute of Technology, ETH-Zentrum, CH-8092 Zurich, Switzerland
b Department of Chemical and Process Engineering, Warsaw Universit 3, of Technology; PL-00-645 Warsaw, Poland

Abstract

The convective and diffusional mass transfer occurring in combined thermoanalyser-mass spectrometer systems can cause significant deviation between measured thermoanalytical and mass spectrometric curves. Based on experimental studies of the decomposition of CaCO3, a model has been developed which allows to interrelate the thermoanalytical (DTG) and mass spectrometric curves and provides a criterion defining under which conditions (carrier gas-flow rate and diffusivity of evolved gas) the disguising mass-transfer influences can be neglected. The criterion relates the total residence time Ttot of the gas in the experimental system to the characteristic time tN of the gravimetrically recorded decomposition process and allows to quantify the agreement between the thermoanalytical and mass spectrometric curves.

View Study : Thermochimica Acta, Vol. 295 (1997) 1-2, 59-71
http://www.sciencedirect.com/science/article/pii/S0040603197001019

 


 

Influence of Experimental Conditions on the Kinetic Parameters of Gas-Solid Reactions - Parametric Sensitivity of Thermal Analysis

B. Roduit, M. Maciejewski, A.Baiker

Abstract

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.
The confidence space, in which the kinetic parameters, calculated for "standard conditions", fit the kinetics of NiO reduction properly, was calculated taking into account the influence of all investigated variables.
The results illustrate the great influence of the experimental conditions on the measured thermoanalytic curves ("parametric sensitivity") and demonstrate the limited validity of kinetic data calculated from experiments carried out under arbitrary chosen conditions.

View Study : Thermochimica Acta, Vol. 282-283 (1996), 101-119
http://www.sciencedirect.com/science/article/pii/0040603196028821