Stabilisers are an integral part of a propellant composition. They are essential for ensuring the chemical stability of nitrate-ester based propellants, preventing oxidation, chain scission and uncontrolled heat generation. Progress is being made, especially in Europe, with REACh legislation (1907/2006) to use more environmentally-friendly compounds. New stabilisers with a greener environmental profile and producing less toxic daughter products have been investigated by several groups, and several compounds demonstrated even better performances - more chemical stability and therefore longer shelf lives than formulations with the currently-used stabilisers. Additionally, the good efficiencies and lower toxicities of the daughter products of the "green" stabilisers are also evaluated. This paper is a continuation of our previous work and demonstrates that for industrially-manufactured propellants, that the tests performed by four different entities validate the stability and compatibility of the propellants, investigated previously on a laboratory scale, providing the community with safer formulations for the environment and health. image

The evaluation of the shelf life of, for example, food, pharmaceutical materials, polymers, and energetic materials at room or daily climate fluctuation temperatures requires kinetic analysis in temperature ranges which are as similar as possible to those at which the products will be stored or transported in. A comparison of the results of the evaluation of the shelf life of a propellant and a vaccine calculated by advanced kinetics and simplified 0th and 1st order kinetic models is presented. The obtained simulations show that the application of simplified kinetics or the commonly used mean kinetic temperature approach may result in an imprecise estimation of the shelf life. The implementation of the kinetic parameters obtained from advanced kinetic analyses into programmable data loggers allows the continuous online evaluation and display on a smartphone of the current extent of the deterioration of materials. The proposed approach is universal and can be used for any goods, any methods of shelf life determination, and any type of data loggers. Presented in this study, the continuous evaluation of the shelf life of perishable goods based on the Internet of Things (IoT) paradigm helps in the optimal storage/shipment and results in a significant decrease of waste.

Simulations of SADT values based on the heat balance of the system are presented for azobisisobutyronitrile (AIBN). These simulations used kinetic parameters obtained from heat flow calorimetry experiments performed at temperatures in the stability range of low-temperature (L-T) polymorph of AIBN. Thermal Activity Monitor (TAM) data were collected in the range of 55-70 degrees C. The simulated SADT value for L-T AIBN amounts to 46 degrees C. This is very similar to the computed results obtained in the RAM project (Malow et al., 2015; Roduit et al., 2015; Moukhina, 2015; Kossoy et al., 2015) for the high-temperature (H-T) form of AIBN which amounts to 47 degrees C and is also in full agreement with the large scale experimentally found SADT of AIBN (47 degrees C) (Malow et al., 2015). The prerequisites for collecting proper kinetic data for the quasi-AC type energetic materials in which the phase change phenomena (polymorphic transformation or melting) precedes the decomposition are discussed. The apparent paradox when the application of incorrect kinetics applied in narrow a or T ranges may sometimes result in the correct predictions of such safety parameters, such as SADT, is also explained.

The latent thermal potential behind any exothermic reactive system is what makes a process dangerous. Under normal operating conditions, this potential remains inactive and controlled. However, under cooling failure or equipment malfunction, this potential may be unleashed and lead to a temperature increase that may trigger secondary reactions and gas formation. The evolution of gaseous products may result in a pressure increase and, ultimately, in the reactor burst if no measures are applied before the point of no return.

The specific problem of non-converted reactant accumulation encountered in fed-batch reactor is a challenging task of process safety. In order to avoid such situation that may lead to a runaway reaction, the reaction kinetics and reactor dynamic must be known. In this work, an innovative approach to determine an optimal feed profile, based on a reaction kinetic and reactor dynamic, is presented. This approach was applied to the reaction system involved in the Morton International Inc. incident. Great improvements were observed in the control of the accumulation, decreasing the number of necessary experiments needed for the scale-up studies.

The present study describes two methods of evaluation of hazard indicators such as Self Accelerating Decomposition Temperature (SADT) or Time to Maximum Rate under adiabatic conditions (TMRad) from the results of the experiments performed in mg scale by Differential Scanning Calorimetry (DSC). We discuss here: (i) the kinetic workflow in which the kinetic parameters of the investigated reaction evaluated from the DSC are used with the heat balance of the system and (ii) a novel merging approach in which DSC data are simultaneously considered with the results of other, temperature recorded experiments as e.g. Accelerating Rate Calorimetry (ARC), large scale experiments as e.g. cookoff, Dewar or SADT determination according to STANAG 4383 and UN regulations (Tests H.4 and H.1), respectively. The commonly kinetic-based approach is discussed and its results confirmed by those obtained in common project with Federal Institute for Materials Research and Testing, Berlin, Germany (BAM) in which the SADT for AIBN was investigated. The novel merging approach is illustrated by the results of the linked DSC-UN test H.1 data and DSC-ARC results applied for SADT determination and for evaluation of TMRad for any starting temperature for AIBN.

The paper presents the results of the common project performed with the Federal Institute for Materials Research and Testing, Berlin, Germany (BAM) concerning the comparison of the experimental results with simulations based on the application of the kinetic-based method and heat balance of the system for the determination of the self accelerating decomposition temperature (SADT). The substantial potential of the kinetic-based method is illustrated by the results of the simulation of SADT of azobisisobutyronitrile (AIBN). The influence of sample mass and overall heat transfer coefficient on the SADT values were simulated and discussed. Simulated SADT values were verified experimentally with a series of large-scale experiments (UN test H.1 [11) performed with packaging of 5,20 and 50 kg of AIBN in an oven at constant temperatures. Additionally, the results of small-scale test H.4 for SADT determination based on the heat loss similarity as described in details in the UN Manual [1] were compared with the simulated data based on kinetic approach. The paper presents also the basic principles of a new kinetic analysis workflow in which the heat flow traces (e.g., DSC) are simultaneously considered with results of large-scale tests as e.g., H.1 or H.4. Application of the newly proposed kinetic workflow may increase accuracy of simulations of SADT based on results collected in the mg-scale and considerably decrease the amount of expensive and time consuming experiments in kg-scale tests. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Keywords: Kinetic ; Scale-up ; Calorimetric Reference EPFL-CONF-207811 Record created on 2015-05-11, modified on 2017-11-13

Chemical incidents are typically caused by loss of control, resulting in runaway reactions or process deviations in different stages of the production. In the case of fed-batch reactors, the problem generally encountered is the accumulation of heat. This is directly related to the temperature of the process, the reaction kinetics and adiabatic temperature rise, which is the maximum temperature attainable in the event of cooling failure. The main possibility to control the heat accumulation is the use of a well-controlled adapted feed. The feed rate can be adjusted by using reaction and reactor dynamic models coupled to Model Predictive Control. Thereby, it is possible to predict the best feed profile respecting the safety constraints.

•Method for the prediction of the thermal stability using discontinuously collected sparse data was proposed.•Modified kinetic and model selection approaches were used in kinetic computations.•Data were simulated by the combination of two kinetic models without limitation of the number of the reaction stages.•Model selection procedure was based on Akaike and Bayesian information criteria.•Proposed methods of kinetic and model selection were verified by simulation of generated data with known, arbitrarily chosen kinetic parameters.

The method of determination of the thermal hazard properties of reactive chemicals from DSC experiments is illustrated by the results of SADT simulations performed with azobisisobutyronitrile (AIBN). The kinetics of decomposition of AIBN in the solid state was investigated in a narrow temperature window of 72–94 °C, just below the sample melting. The kinetic parameters of the decomposition were evaluated by differential isoconversional method. The very good fit of the experimental results by the simulation curves, based on the determined kinetic parameters, indicated the correctness of the kinetic description of the process. Application of the kinetic parameters, together with the heat balance performed by numerical analysis, allowed scale-up of thermal behaviour from mg- to kg-scale and simulation of SADT. The study presents the evaluation of the influence of the overall heat transfer coefficient U on the SADT value. The results obtained clearly illustrate also the dependence of SADT on the sample mass. The tenfold increase of the mass from 5 to 50 kg results in the decrease of the SADT from 50 to 43 °C. Determination of the reaction kinetics, describing the rate of heat generation, and the heat balance in the system, based on Frank-Kamenetskii approach, was calculated using AKTS Thermokinetics and Thermal Safety software.

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. (C) 2014 Elsevier B.V. All rights reserved.

The paper presents the results of simulations of the influence of the reaction progress of the material at the moment of the beginning of the thermal experiment (called as ??storage) on the thermal behavior in mg- (as in DSC), kg- (SADT or cookoff), and ton- (TMRad) scales. Simulations were carried out using the general autocatalytic (first-order reaction with autocatalysis, Kamal-Sourour, KS), nucleation (Avrami-Erofeev, A4) and first-order (F1) reaction models. Results of simulation show that influence of ??storage is significant for materials decomposing according to autocatalytic models and negligible for those decomposing according to the first-order kinetics. For the determination of the importance of ??storage value on the course of reaction and, further, on the simulations of the thermal behavior of the materials, we propose the simple AKTS test which requires only two non-isothermal runs with identical, arbitrarily chosen heating rates. The goal of this test consists in controlled, artificial aging of the sample, reflecting the minor changes of reaction progress during sample storage. In other words, the test allows comparison of the thermal behavior of the same sample having, however, in two following experiments, slightly different ??storage values. Additionally we present the simulations of the dependence of thermal properties of the materials on the ??storage under real, climate conditions. All presented results indicate that the decomposition progress of the materials at the beginning of any thermal treatment must be considered as an important parameter, beside commonly applied kinetic triplet, during prediction of the sample properties.

Chemiluminescence (CL) includes all luminescence phenomena resulting from chemical reactions therefore due to the fact that the oxidative degradation process of the organics is combined with the emission of light this method can be applied for investigating the course of the oxidation processes. Commonly applied methods of the investigation of the oxidation such as determination of oxidation induction time (OIT) or oxidation onset temperature (OOT) using Differential Scanning Calorimetry (DSC) or other conventional thermoanalytical methods are sometimes unsuitable for long-term prediction of oxidative behaviour because of the use of elevated temperatures during these experiments: the high temperatures may invoke reaction pathways which are different from those encountered under the conditions of use. Compared to DSC and other conventional thermo-analytical methods, CL offers interesting advantages: due to its much higher sensitivity, experiments can be performed at much lower temperatures i.e. closer to the application related conditions. This fact is of the importance for the characterisation of substances with low temperature melting points, glass transitions, etc. The outstanding baseline stability of CL is of great benefit when performing long-term experiments; moreover, the CL-signal is related exclusively to the oxidation processes and therefore is not superposed by the signals resulting from the other reactions, including phase transitions. 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 chemiluminescence’s 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 stability test procedure according to NATO-AOP 48 Ed. 2 commonly applied for the explosives and nitrocellulose-based propellants is based on the assumption that the kinetic description of the process of stabilizer depletion can be done by applying the reaction-order (RO) model for the fitting experimental data. In the present paper another procedure is proposed by application more general Prout-Tompkins (PT) model based on the autocatalytic character of the reaction. Presented computer simulations indicate that PT model allows much better fit of the processes which kinetics is not fully determined. Application of proposed model significantly decreases the number of experimental points required for the prediction of the propellant properties at 25 degrees C or after 10 years of storage (t(25). and T-10-values, respectively). The results of elaboration of experimental data of single- and double- based propellants calculated with RO and PT models are presented.

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 8.0K/min） and isothermal（range of 200~260℃） modes.The kinetic parameters obtained with AKTS-Thermokinetics Software were applied for calculating reaction rate and progress under different heating rates and temperatures and verified by comparing simulated and experimental signals.After application of the heat balance to compare the amount of heat generated during reaction and its removal from the system,the knowledge of reaction rate at any temperature profiles allowed the determination of the temperature increase due to the self-heating in adiabatic and pseudo-adiabatic conditions.Applied advanced kinetic approach allowed simulation the course of the Heat-Wait-Search（HWS） mode of operation of adiabatic calorimeters.The thermal safety diagram depicting dependence of Time to Maximum Rate（TMR） on the initial temperature was calculated and compared with the results of HWS experiments carried out in the system with Ф-factor amounting to 3.2.The influence of the Ф-factor and reaction progress reached at the end of the HWS monitoring on the TMR is discussed.Presented calculations clearly indicate that even very minor reaction progress reduces the TMRad of 24h characteristic for a sample with initial reaction progress amounting to zero.Described estimation method can be verified by just one HWS-ARC,or by one correctly chosen ISO-ARC run of reasonable duration by knowing in advance the dependence of the TMR on the initial temperature for any Ф-factor.Proposed procedure results in significant shortening of the measuring time compared to a safety hazard approach based on series of ARC experiments carried out at the beginning of a process safety evaluation.

Propellants can burn so rapidly that the initial rise of pressure in weapons may be faster than desired. To avoid this unwanted effect, burning rate of the propellants is moderated by applying a surface coating. Coating agents are usually deterrents (moderants), substances that gelatinize or plasticise the nitrocellulose matrix of the propellants decreasing its initial burning rate, therefore, in turn, the rate of gaseous phase formation. The knowledge of the diffusion rate of deterrents helps therefore in developing propellants with superior ballistic performance. Another parameter, namely the rate of the migration of deterrent into the propellant matrix during ageing / storing is also important as it influences the ballistic shelf-life i.e. the period of time during which the ballistic requirements are fulfilled. As migration measurements are often difficult, expensive and timeconsuming the development of the simulation tools of above processes seems to be of a great importance. The present paper describes the simulation method for deterrent and blasting oil diffusion in double base propellant applying the temperature dependence of the diffusion coefficients D determined in isothermal experiments and taking into account the influence of the swelling effect of the propellant matrix. The simulations were done using the AKTS-SML software [1], which allowed considering the migration of both, deterrent and nitroglycerine through the swollen matrix of the propellant. Furthermore, after determination of the temperature dependence of the diffusion coefficient D, it was possible to predict the deterrent migration under any, arbitrarily chosen temperature profile such as oscillatory temperature mode, real atmospheric temperature profiles or under temperature mode corresponding to atmospheric changes according to STANAG 2895 [2].

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.