Authors:L. Wu, K. Chen, S. Cheng, B. Lee, and C. Shu
Hydrogen peroxide (H2O2) is popularly employed as a reaction reagent in cleaning processes for the chemical industry and semiconductor plants. By
using differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2), this study focused on the thermal decomposition
reaction of H2O2 mixed with sulfuric acid (H2SO4) with low (0.1, 0.5 and 1.0 N), and high concentrations of 96 mass%, respectively. Thermokinetic data, such as exothermic
onset temperature (T0), heat of decomposition (ΔHd), pressure rise rate (dP/dt), and self-heating rate (dT/dt), were obtained and assessed by the DSC and VSP2 experiments. From the thermal decomposition reaction on various concentrations
of H2SO4, the experimental data of T0, ΔH, dP/dt, and dT/dt were obtained. Comparisons of the reactivity for H2O2 and H2O2 mixed with H2SO4 (lower and higher concentrations) were evaluated to corroborate the decomposition reaction in these systems.
Authors:Chun-Chin Huang, Jiou-Jhu Peng, Sheng-Hung Wu, Hung-Yi Hou, Mei-Li You, and Chi-Min Shu
Cumene hydroperoxide (CHP) being catalyzed by acid is one of the crucial processes for producing phenol and acetone globally.
However, it is thermally unstable to the runaway reaction readily. In this study, various concentrations of phenol and acetone
were added into CHP for determination of thermal hazards. Differential scanning calorimetry (DSC) tests were used to obtain
the parameters of exothermic behaviors under dynamic screening. The parameters included exothermic onset temperature (T0), heat of decomposition (ΔHd), and exothermic peak temperature (Tp). Vent sizing package 2 (VSP2) was employed to receive the maximum pressure (Pmax), the maximum temperature (Tmax), the self-heating rate (dT/dt), maximum pressure rise rate ((dP/dt)max), and adiabatic time to maximum rate ((TMR)ad) under the worst case. Finally, a procedure for predicting thermal hazard data was developed. The results revealed that phenol
and acetone sharply caused a exothermic reaction of CHP. As a result, phenol and acetone are important indicators that may
cause a thermal hazard in the manufacturing process.
This work refers to a study of the thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7 tetrazocine (HMX) by differential
scanning calorimetry (DSC) in non-isothermal conditions, with heating rates from1 to 25C min−1. The influence of the heating rate, the particle and the sample size were verified. The activation energy was calculated
using the peak temperature shift method, proposed by Ozawa and a significant variation in the results was observed according
to the range of the used heating rates. As the heating rate was increased, different conversions and self-heating effects
were observed at the respective DSC peaks, indicating that the use of this method was inadequate and it may lead to incorrect
results, which, in turn, could explain the wide range of activation energy values published in literature. At lower heating
rates HMX decomposition occurs on the solid state and at higher ones decomposition occurs after melting practically at the
same temperature, which does not depend on the heating rate.
In petrochemistry, dicumyl peroxide (DCPO) is used in various resins for improving physical properties, which was produced
by cumene hydroperoxide (CHP) with oxidization reaction, redox reaction, and dehydration reaction. The reactant, CHP, is a
typical organic hydroperoxide and has been intrinsically unstable and reactive due to its bivalent -O-O- structure which can
be broken readily with bond-dissociation energy. This sequence on sensitive study aimed at the thermal hazard evaluation for
the reactive and incompatible characteristics of CHP mixed with various inorganic alkaline solutions. Differential scanning
calorimetry (DSC) and vent sizing package 2 (VSP2) were used to analyze the thermal hazards and runaway reaction of redox
system, such as decomposition of CHP in cumene solution and CHP react with inorganic alkaline solutions, exothermic onset
temperature, peak power, heat of decomposition of dynamic scanning tests, adiabatic self-heating rate, pressure rise rate,
maximum temperature, maximum pressure of reaction system, etc. The results of the tests have proven helpful in establishing
safe handling, storage, transportation, and disposal guidelines.
Authors:V. Torra, C. Auguet, A. Isalgue, F. Lovey, A. Sepulveda, and H. Soul
The use of Shape Memory Alloys (SMA) in technical applications as damping in civil engineering structures requires the characterization
of the alloy for each specific application. This involves the evolution of the mechanical properties and damping capacity
with the number of cycles, frequency, maximum deformation, applied stresses, and the evolution of the alloy with aging time
and temperature. In particular, the temperature effects associated to self-heating need to be evaluated. In continuous cycling
the effects of latent heat, the associated dissipation induced by the hysteresis, the heat flow to surroundings and the cycling
frequency induce different states of temperature in the specimen, which in turn produces changes in the transformation-retransformation
stresses. In this article, the temperature effects associated to cycling are outlined for different cycling frequencies. The
results show that, for relatively faster frequency the temperature arrives at an oscillatory state superimposed to an exponential
increase. For lower frequencies, some parts of the sample attain temperatures below room temperature. The experimental results
are represented with an elementary model (the 1-body model or the Tian equation used in calorimetric representation) of heat
transfer. For the higher fracture where life requirements are associated to damping in stayed cables for bridges, the results
show (for the NiTi alloy) a reduction of the hysteresis width as the frequency increases for deformations up to 8%. For reduced
deformation, under 2% appears an asymptotic behavior where the frictional area is practically independent of the cycling frequency
(up to 20 Hz). In addition, it is shown that more than 4 million of working cycles can be attained if the maximum applied
stress is kept below a threshold of about 200 MPa. Although under this condition the deformation must remain lower than 2%
a reasonable damping capacity can still be obtained.
Authors:B. Roduit, Ch. Borgeat, B. Berger, P. Folly, B. Alonso, and J. N. Aebischer
Summary 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. For self-heating reactions, incorrect kinetic description of the process is usually the main source of serious errors for the determination of the time to maximum rate under adiabatic conditions (TMRad). It is hazardous to develop safety predictive models that are based on simplified kinetics determined by thermoanalytical methods. Applications of finite element analysis (FEA) and accurate kinetic description allow determination of the effect of scale, geometry, heat transfer, thermal conductivity and ambient temperature on the heat accumulation conditions. Due to limited thermal conductivity, a progressive temperature increase in the sample can easily take place resulting in a thermal explosion. Use of both, kinetics and FEA , enables the determination of the reaction progress and temperature profiles in storage containers. The reaction progress and temperature can be determined quantitatively at every point in time and in space. This information is essential for the design of containers of self-reactive chemicals, cooling systems and the measures to be taken in the event of a cooling failure.
Decomposition of urea nitrate in an initially evacuated system gave sigmoidal pressurevs. time curves. The experimental kinetic data fit the growing nuclei model with a measured enthalpy of activation of 142±12.5 kJ/mole as compared to 115±11.3 kJ/mole obtained thermogravimetrically. This higher value ofΔH‡ is explained on the basis of two factors: 1) the inhibitory effect of the product gases and 2) self heating, whose extent increasedΔH‡ by about 12.5 kJ/mole.
Authors:Dao-Xing Sun, Xiao Miao, Chuan-Xin Xie, Jing Gu, and Rong Li
tended to be dominant and the heat flow decreased with the time.
The reaction temperature, self-heating rate, and pressure data may be collected during the exothermic processes with ARC. It is effective
of self-heating leading to thermal runaway, etc., still persist. Yuhai and Shilin [ 2 ] investigated the preparation technology and the safety analysis of the production process of smokeless fireworks made by the expired single base propellant
Authors:Sheng-Hung Wu, Hung-Cheng Chou, Ryh-Nan Pan, Yi-Hao Huang, Jao-Jia Horng, Jen-Hao Chi, and Chi-Min Shu
. When the maximum self-heating rate compared with the time constant is the same in the system, then the temperature will rise to T NR [ 8 ]. The E a and A is developed from Arrhenius equation that is displayed in Eq. 3 . The E a calculation