Possibilities of applying Piloyan method of determination of decomposition activation energies in differential thermal analysis of polynitroaromatic compounds and their derivatives

The Piloyan activation energiesE of decomposition and the initial temperaturesT _D of the exotherms of hexanitrobiphenyl (HNB), nonanitro-m-terphenyl (NONA), tripicryl-s-triazine (TPT) and 1,4,5,8-tetranitronaphthalene (TENN) have been determined by means of non-isothermal DTA. Due to its volatility in the zone of the beginning of thermal decomposition onlyT _D values are specified fors-trinitrobenzene (TNB). From the values ofE ·T _D ^–1 for HNB and from the derived values ofE ·T _D ^–1 for TNB on the one hand, and from the published values of the Arrhenius parameters obtained by means of the manometric method on the other, relationships have been derived. The relationship betweenE ·T _D ^–1 and the standard activation enthropy is considered relevant.

---

Zusammenfassung Die AktivierungsenergienE nach Piloyan der Zersetzung sowie die AnfangstemperaturT _D der exothermen Vorgänge von Hexanitrobiphenyl (HNB), Nonanitro-m-terphenyl (NONA), Tripicryl-s-triazin (TPT) und 1,4,5,8-Tetranitronaphthalin (TENN) wurden durch nicht-isotherme DTA bestimmt. Wegen seiner Flüchtigkeit im Bereich der beginnenden thermischen Zersetzung wurden fürs-Trinitrobenzol (TNB) nur dieT _D-Werte angegeben. Von den Werten vonE.T _D ^–1 für HNB und von den abgeleiteten Werten vonE.T _D ^–1 für TNB einerseits und von den durch manometrische Methoden erhaltenen veröffentlichten Angaben der Arrhenius-Parameter andererseits wurden die Zusammenhänge ermittelt. Der zwischen dem AusdruckE.T _D ^–1 und der standarden Aktivierungsenthropie bestehende Zusammenhang wird als wesentlich hervorgehoben.

---

Résumé On a détermine par ATD les températures initialesT _D des phénomènes exother miques de l'hexanitrobiphényle (HNB), du nonanitro-m-terphényle(NONA),du tripicryle-s-triazine (TPT) et du 1,4,5,8-tétranitronaphtalène (TENN) et les énergies d'activationE de la composition d'après la méthode de Piloyan. En raison de la volatilité dus-trinitrobenzène (TNB) dans la zone de la décomposition thermique initiale, on n'a déterminé pour celui-ci, que les valeursT _D. On a dégagé des corrélations d'une part, à partir des valeurs.E.T _D ^–1 pour HNB et des valeurs dérivées deE.T _D ^–1 pour TNB et d'autre part, à partir des valeurs publiées des paramètres d'Arrhenius obtenues par la méthode manométrique. On a souligné l'importance de la corrélation qui existe entre le termeE.T _D ^–1 et l'entropie d'activation standard.

---

E T _D (). -- (), -- () 1,4,5,8- (). - (), , T _D . E.T _D ^{– 1} , , , . , E. T _D ^–1 .

---

---

The author is obliged to Mrs Klara Kováová, M. S., for her most generous help in processing the results of measurements with the Wang 2200 computer.     

Possibilities of applying the Piloyan method of determination of decomposition activation energies in the differential thermal analysis of polynitroaromatic compounds and their derivatives

By means of non-isothermal DTA in its simple form the initial exotherm temperaturesT _D of 2,4-dinitrotoluene, 2,6-dinitrotoluene, 2,4,6-trinitrotoluene, 1,5-dinitronaphtalene, 1,8-dinitronaphthalene and 1,4,5,8-tetranitronaphthalene have been determined. By application of the Piloyan method to these measurements, the activation energiesE arising from the decompositions of these compounds were established. The results are discussed from the point of view of the molecular structures of the polynitro compounds.

---

Zusammenfassung Durch nicht-isotherme DTA in ihrer einfachen Form wurde der BeginnT _D der Exothermen von 2,4-Dinitrotoluol, 2,6-Dinitrotoluol, 2,4,6-Trinitrotoluol, 1,5-Dinitronaphthalin, 1,8-Dinitronaphthalin, 1,4,5-Trinitronaphthalin und 1,4,5,8-Tetranaphthalin bestimmt. Durch Anwendung der Methode von Piloyan auf diese Messungen wurden die aus der Zersetzung o.a. Verbindungen herrührenden AktivierungsenergienE spezifiziert. Die erhaltenen Ergebnisse werden unter dem Aspekt der Molekularstruktur der untersuchten Polynitroverbindungen erörtert.

---

Résumé On a déterminé par ATD les températures initialesT _D des phénomènes exothermiques du 2,4-dinitrotoluène, 2,6-dinitrotoluène, 2,4,6-trinitrotoluène, 1,5-dinitronaphtalène, 1,8-dinitronaphtalène, 1,4,5-trinitronaphtalène et 1,4,5,8-tétranitrophtalène. Les énergies d'activationE de la décomposition de ces composés ont été déterminées à l'aide de la mé thode de Piloyan. Les résultats obtenus sont discutés sous l'aspect de la structure moléculaire de ces composés.

---

T _D 2,4-, 2,6-, 2,4,6- , 1,5- 1,8- , 1,4,5- 1,4,5,8- . , E .

     

Possibilities of applying the Piloyan method of determination of decomposition activation energies in the differential thermal analysis of polynitroaromatic compounds and of their derivatives

Conditions are presented for application of the Piloyan method to the DTA of poly-nitro aromatic compounds. Activation energies (E) of the thermal decomposition and the initial valuesT _D of the exotherms are determined for trinitrotoluene, trinitro-m-xylene, trinitromesitylene, picryl chloride and dichlorotrinitrobenzene. Linear relationships are derived between the termsE · T _D ^? and published kinetic data on these compounds, obtained by an isothermal manometric method. The mechanisms of the primary steps in the thermolyses of these polynitro compounds are discussed. A negative influence on their thermal stability has been confirmed, arising from the contact of the measured compounds with the glass surface.     

Possibilities of applying the piloyan method of determination of decomposition activation energies in the differential thermal analysis of polynitroaromatic compounds and their derivatives

Piloyan activation energiesE as well as initals of exothermT _D of sevenN-monoalkyl and fiveN,N-dialkyl-2,4-dinitroanilines were determined. Relationships were found between the T_D values and R_f factors as well asE values and those R_M functions and also theET _D ^–1 term and R_M functions.

---

Zusammenfassung Die AktivierungsenergienE nach Piloyan sowie die Anfangswerte der ExothermenT _D wurden für siebenN-Monoalkyl- und fünfN,N-Dialkyl-2,4-dinitroaniline bestimmt. Die Zusammenhänge zwischen denT _D-Werten und den papierchromatographischenR _f-Faktoren der gemessenen Dinitroaniline wurden abgeleitet und erörtert. Desgleichen wurden auch die Zusammenhänge zwischen denE-Werten und denR _M-Funktionen der Papierchromatographie abgeleitet und erörtert. Auch zwischen dem AusdruckE ·T _D ^–1 und denR _M-Funktionen wurde ein Zusammenhang gefunden.

---

Résumé On a déterminé les températures initialesT _D de l'effet exothermique ainsi que les énergies d'activationE d'après la méthode de Piloyan, de sept N-mono alcoyl et cinqN,N-dialcoyl-2, 4-dinitroanilines. Une corrélation entre les valeursT _D et les facteursR _f de la Chromatographie sur papier des dinitroanilines étudiées a été trouvée et discutée, ainsi qu'entre les valeursE et les fonctionsR _M de la Chromatographie sur papier. Une relation entre le termeE ·T _D ^–1 et les fonctionsR _M a également été trouvée.

---

E T _D N- N,N- -2,4- . _D R _f , E R _M. E. _D ^–1 R _M.

---

---

The authors would like to thank Mrs. Anna Collàkovà for careful DTA measurements, and Dr. Ladislav Smolka for help in treatment of the measured results with the Wang 600 computer.     

Possibilities of applying the Piloyan method of determination of decomposition activation energies

Activation energies (E) of the thermal decomposition and the initial valuesT _D of the exotherms are determined for trinitroaniline, trinitro-m-phenylenediamine, trinitrotriaminobenzene, trinitrophenol, trinitroresorcinol, trinitro-m-cresol and hexanitrooxanilide. Linear relationships are derived between the termsE.T _D ^1? and published kinetics data on these compounds, obtained by an isothermal manometric method. The mechanisms of the primary steps in the thermolyses of these polynitro compounds are discussed. A positive influence on their thermal stability has been confirmed, arising from the contact of the measured compounds with the glass surface.     

Thermal stabilities of polynitroaromatic compounds and their derivatives

The thermal stabilities of 33 polynitroaromatic compounds and their derivatives were determined using non-isothermal differential thermal analysis (DTA). For twelve of these, the thermal stabilities of their mixtures with 1,3,5-trinitrobenzene was also determined. The results obtained are discussed from a molecular structural point of view.The results obtained from DTA measurements are compared with the published data which were derived from the results of the application of the manometric method to the study of the thermal reactivity of polynitroaromatic compounds. The differences which exist between the conclusions reached on basis of DTA application, on the one hand, and those obtained on the basis of the application of the manometric method, on the other hand, are discussed.Using the published relationship for the calculation of the temperature limit (T_max) for the use of polynitroaromatic compounds as secondary thermostable explosives, T_max values are calculated for the compounds being measured. A relationship is derived between T_max and T_D the initial exothermal decomposition temperature obtained from the DTA of the studied compounds.     

Non-isothermal differential thermal analysis in the study of the initial state of the thermal decomposition of polynitroaromatic compounds in the condensed state

The activation energies, E, of the decomposition of picramide and its N-methyl-,N-ethyl-,N-n-propyl- and N-n-butyl-derivatives are determined by means of non-isothermal DTA, in its simple form, as well as by the Piloyan method. A relationship is found between the E values of the above-mentioned compounds and the published values of the moments of inertia of the corresponding n-alkyl groups. Taking into account data published previously, which were obtained by application of the Piloyan method in the DTA of polynitroaromates, it is concluded that by suitable selection of DTA measurement conditions, it is possible to record the early part of the exothermal decomposition of the above-mentioned compounds were no autocatalytic influence exists. Attention is also paid to the thermostability of the polynitroaromates due to their contact with the construction materials employed in the course of thermolysis.     

The relationship between differential thermal analysis data and the detonation characteristics of polynitroaromatic compounds

The thermal stabilities of 37 polynitroaromatic compounds are specified by means of non-isothermal DTA. The initial temperatures of the exotherms T_D, as well as the Piloyan decomposition activation energies, E, of the compounds are determined.A relationship is derived between ET^?1_D and the detonation characteristics of the compounds being measured. It is shown that allocation of the measured compounds to separate forms of the determined relationship is, in addition to thermochemical factors, also determined by the electron configuration and steric conditions in the reaction center of the given molecule.     

A link between impact sensitivity of energetic compounds and their activation energies of thermal decomposition

A new relationship is introduced between impact sensitivity of energetic compounds and their activation energies of thermal decomposition. In this relationship, the impact sensitivity of an energetic compound with general formula C_aH_bN_cO_d is a function of its activation energy of thermal decomposition as well as the ratio of \( \left( {\frac{{n_{\text{H}} }}{{n_{\text{O}} }}} \right) \) and the contribution of specific molecular structural parameters. The new correlation can help us to elucidate the mechanism of initiation of energetic materials by impact. It can be used to predict the magnitude of impact sensitivity of new energetic materials. The new correlation has the root mean square and the average deviations of 2.22 and 1.79 J, respectively, for 40 energetic compounds with different molecular structures. The proposed new method is also tested for 11 energetic compounds, which have complex molecular structures, e.g., 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane and 1,3,7,9-tetranitrophenoxazine.     

Estimation of activation energies from differential thermal analysis curves

An average activation energy ΔE3 of 31.7 ± 10.0 kcal/mole was calculated from exothermic peaks of urea nitrate differential thermal analysis (DTA) curves using the Murray and White equation and various other reaction rate equations developed by the authors. An average enthalpy of activation, ΔH3 of 30.8 ±9.7 kcal/mole was calculated from the same results. The values of ΔE3 and ΔH3 differed by a fraction of a kcal/mole indicating that ΔE3 <ΔH3 cannot be differentiated experimentally in our study. Application of the Kissinger method of calculating ΔE3 and ΔH3 produced respectively 21.6 ±7.9 and 20.7 ±8.0 kcal/mole, which are quite low. The values of ΔE3 and ΔH3 calculated thermogravimetrically were 28.1, ± 1.1 kcal/mole and 27.6 ± 1.2 kcal/mole which are close to those obtained from the Murray and White approach and the authors' approach to treatment of the DTA data. These results illustrate the pronounced effect of self heating on calculation of activation energies. The Kissinger method of calculating the reaction order developed for endothermic DTA peaks produced good results when applied to the present DTA study.     

Errors in the determination of activation energies of solid-state reactions by the Piloyan method,as a function of the reaction mechanism

The errors in the activation energies of solid-state reactions determined with the Piloyan method are more larger than those previously assumed in the literature. On the other hand, the errors in the kinetic parameters are strongly dependent on the kinetic law obeyed by the reaction. A theoretical explanation of this behaviour is given.

---

Zusammenfassung Die Fehler der nach der Piloyan-Methode bestimmten Aktivierungsenergien von Festkörperreaktionen sind grö\er als bisher in der Literatur angenommen und stark abhÄngig von der Reaktionsordnung. Eine theoretische ErklÄrung dieses Verhaltens wird gegeben.

---

, , . , , , . .

     

A novel method for risk assessment of electrostatic sensitivity of nitroaromatics through their activation energies of thermal decomposition

This study presents a novel relationship between electric spark sensitivity of nitroaromatic energetic compounds and their activation energies of thermal decomposition. The new correlation can help to elucidate the mechanism of initiation of energetic materials by electric spark. It can be used to predict the magnitude of electric spark sensitivity of new nitroaromatics, which is difficult to measure. The methodology assumes that electric spark sensitivity of a nitroaromatic energetic compound with general formula C_aH_bN_cO_d can be expressed as a function of its activation energy of thermal decomposition as well as optimized elemental composition and the contribution of specific molecular structural parameters. The new correlation has the root mean square and the average deviations of 1.43 and 1.17 J, respectively, for 22 nitroaromatic energetic compounds with different molecular structures. The proposed new method is also tested for eight nitroaromatic energetic compounds, which have complex molecular structures, e.g., 1,3,7,9-tetranitrophenoxazine, 2,4,6-tris(2,4,6-trinitrophenyl)-1,3,5-triazine, and 1-(2,4,6-trinitrophenyl)-5,7-dinitrobenzotriazole.     

Limiting temperatures of the thermal decomposition of polymers and their determination by rapid thermal analysis

Experimental and theoretical foundations are established for the limiting temperatures of thermal decomposition of thermoplastic polymers. The correlation between the limiting temperatures and the intermolecular interactions of the polymers investigated is reported.

---

Zusammenfassung Experimentelle und theoretische Grundlagen der Grenztemperaturen der thermischen Zersetzung von thermoplastischen Polymeren werden behandelt. Es besteht eine Korrelation zwischen den Grenztemperaturen und den intermolekularen Wechselwirkungen der untersuchten Polymere.

---

. .

     

Reliability of the volatilization method for determination of the activation energy in the thermal decomposition of polymers

The LPTD-MS method, used to determine kinetic parameters in the thermal degradation of polymers by means of volatilization curves, was applied to TG data and the results were compared with those obtained by the methods of Flynn & Wall, Friedman, Freeman & Carroll, and Coast & Redfern.

---

Zusammenfassung Die LPTD-MS-Methode, benutzt zur Bestimmung der kinetischen Parameter des thermischen Abbaus von Polymeren aus Verflüchtigungskurven, wurde auf TG-Daten angewandt und die Ergebnisse wurden mit denen verglichen, die nach den Methoden von Flynn und Wall, Friedman, Freeman und Carroll sowie Coats und Redfern erhalten wurden.

---

Резюме Совмещенньй метод ЛПТД-МС, используемый для определения кинетических параметров реакции термического распада полимеров с помощыью кривых испарения, бып применен к данным. ТГ. Результатю были сопоставлены с теми, которые были получены методами Флинна и Уолла, фриидмена, фримена и Карролла, а также Коуста и Радферна.

     

On the non-isothermal determination of activation energy for thermal decomposition reactions

Attention is called to the frequently encountered linear sector in the isothermal course of the topochemical processes which is used in the kinetic treatment of the differential curves of thermal CoOOH decomposition. The effect of sample weight and heating rate on the values of the activation energy of this process under polythermal conditions has been investigated. Most of the values obtained are in good agreement among themselves as well as with those found isothermally. Existing differences have been explained satisfactorily.     

Validation of improved simple method for prediction of activation energy of the thermal decomposition of energetic compounds

This study presents a new simple model for predicting activation energy of the thermolysis of various classes of energetic compounds. The new model can help to elucidate the cause of thermal stability and, therefore, shelf life of some energetic compounds. The methodology assumes that activation energy of an energetic compound with general formula C _a H _b N _c O _d can be expressed as a function of optimized elemental composition as well as the contribution of specific molecular structural parameters. The new correlation has the root mean square and the average deviations of 9.8 and 7.4 kJ mol^?1, respectively, for 86 energetic compounds with different molecular structures. The proposed new method is also tested for 20 energetic compounds, which have complex molecular structures, e.g. 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane, 2,4,6-tris(2,4,6-Trinitrophenyl)-1,3,5-triazine and 1-(2,4,6-Trinitrophenyl)-5,7-dinitrobenzotriazole.     

Mass spectra of sulfinamide derivatives and identification of their thermal decomposition products

The mass spectra of 30 sulfinamide derivatives (RSONHR', R' alkyl or p-XC₆H₄) are reported. Most of the spectra had peaks attributable to thermal decomposition products. For some compounds these were identified by pyrolysis under similar conditions to be: RSO₂NHR', RSO₂SR, RSSR and NH₂R' (in all kinds of sulfinyl amides); RSNHR' (in the case of arylsulfinyl arylamides); RSO₂C₆H₄NH₂, RSOC₆H₄NH₂ and RSC₆H₄NH₂ (in the case of arylsulfinyl arylamides of the type of X = H) The mass spectra of the three thermally stable compounds showed that there are several kinds of common fragment ions. The mass spectra of the thermally labile compounds had two groups of ions; (i) characteristic fragment ions of the intact molecules and (ii) the molecular ions of the thermal decomposition products. It was concluded that the sulfinamides give the following ions after electron impact: [M]⁺, [M ? R]⁺, [M ? R + H]⁺, [M ? SO]⁺, [RS]⁺, [NHR']⁺, [NHR' + H]⁺, [RSO]⁺, [RSO + H]⁺, [R]⁺, [R + H]⁺, [R']⁺ and [M ? OH]⁺, and that the thermal decomposition products give the following ions: [RSO₂SR]⁺, [RSSR]⁺, [M ? O]⁺, [M + O]⁺ and [RSOC₆H₄NH₂]⁺.     

Possibilities of low-level determination of silicon in biological materials by activation analysis

The capabilities of neutron and photon activation analysis (NAA and PAA, respectively) for low-level determination of silicon in biological materials have been examined. Sensitivities of a variety of modes of NAA and PAA with radiochemical separation have been evaluated. Results are presented for silicon in reference materials CSRM 12-2-03 Lucerne, Bowen's Kale, NIST SRM-1571 Orchard Leaves, and NIST SRM-1515 Apple Leaves. The results were obtained by employing the 29Si(n,p)29Al reaction with fast reactor neutrons and the radiochemical procedure developed for aluminium separation. Possibilities of further improvement of the silicon determination limit down to the microg g(-1) level by employing NAA and PAA with radiochemical separation are outlined.