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Abstract  

Multi-walled carbon nanotubes (MWCNTs) have remarkable properties. However, their thermal stability characteristics, which may represent potential hazards during the production or utilization stage, concern unsafe or unknown properties researches. Our aim was to analyze the thermokinetic parameters of different heating rates by differential scanning calorimetry (DSC) and thermogravimetric analyzer (TG), and then to compare thermal decomposition energy parameters under various conditions by well-known kinetic equations. MWCNTs were acidified via nitric acid (HNO3) in various concentrations from 3 to 15 N and were characterized by means of Fourier transform infrared (FTIR) spectrometry. For original and modified MWCNTs, we further identified the thermal degradation characteristics of the functional group by TG-FTIR. Finally, we established an effective and prompt procedure for receiving information on thermal decomposition characteristics and reaction hazard of MWCNTs that could be applied as an inherently safer design during normal or upset operation.

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Abstract  

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is a typical highly energetic material that has been widely used in national defense industries since the 1940s. The aim of this study was to establish a reaction kinetic model on thermal decomposition properties via differential scanning calorimetry (DSC) by well-known kinetic equations and kinetic model simulation. Furthermore, the aim also was to compare kinetic algorithms for thermal decomposition energy parameters under various conditions. Experimental results highly depended on the reliability of the kinetic concept applied, which is essentially defined by the proper choice of a mathematical model of a reaction. In addition, the correctness of the methods is used for kinetics evaluation.

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Abstract

With two active O–O peroxide groups, 1,1-bis(tert-butylperoxy)cyclohexane (BTBPC) has a certain degree of thermal instability. It is usually used as an initiator in chemical processes, and therefore reckless operation may result in serious thermal accidents. This study focused on the runaway reactions of BTBPC alone and mixed with various concentrations of nitric acid (1, 2, 4, and 8 N). The essential thermokinetic parameters, such as exothermic onset temperature (T o), activation energy (E a), frequency factor (A), time to maximum rate under adiabatic condition (TMRad) and time to conversion limit (TCL), were evaluated by differential scanning calorimetry at the heating rate of 4 °C min−1, and a kinetics-based curve fitting method was used to assess the thermokinetic parameters. All the results indicated that BTBPC mixed with one more than 4 N nitric acid dramatically increased the degree of thermal hazard in the exothermic peak and became more dangerous. However, it was relatively safe for BTBPC mixed with less than 1 N nitric acid under 34.5 °C.

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Abstract

Methyl ethyl ketone peroxide (MEKPO), which has highly reactive and exothermically unstable characteristics, has been extensively employed in the chemical industries. It has also caused many thermal explosions and runaway reaction accidents in manufacturing processes during the last three decades in Taiwan, Japan, Korea, and China. The goal of this study was to simulate thermal upset by MEKPO for an emergency response. Vent sizing package 2 (VSP2) was used to determine the thermokinetics of 20 mass% MEKPO. Data of thermokinetics and hazard behaviors were employed to simulate thermal explosion in three types of vessel containing 20 mass% MEKPO under various scenarios at the same volume. To compare and appraise the difference of important parameters, such as maximum temperature (T max), maximum pressure (P max), etc. This was necessary and useful for investigating the emergency response procedure associated with industrial applications.

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Abstract

In view of availability, accountability, and applicability, LiFePO4 cathode material has been confirmed to be better than LiCoO2 cathode material. Nevertheless, few related researches were conducted for thermal runaway reaction of the LiFePO4 batteries. In this study, vent sizing package 2 (VSP2) and differential scanning calorimetry were employed to observe the thermal hazard of 18650 lithium-ion batteries and their content—LiFePO4 cathode material, which were manufactured by Commercial Battery, Inc. Two states of the batteries were investigated, which was charged to 3.6 V (fully charged) and 4.2 V (overcharged), respectively, and important parameters were obtained, such as self-heating rate (dT dt −1), pressure-rise rate (dP dt −1), and exothermic onset temperature (T 0). The results showed that T 0 for fully charged is about 199.94 °C and T max is about 243.23 °C. The entire battery for LiFePO4 cathode material is more stable than other lithium-ion batteries, and an entire battery is more dangerous than a single cathode material. For process loss prevention, the data of battery of VSP2 test were applied as reference for design of safer devices.

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Abstract

Methyl ethyl ketone peroxide (MEKPO) is generally applied to manufacturing in the polymerization processes. Due to thermal instability and high exothermic behaviors of MEKPO, if any operation is undertaken recklessly or some environmental effect is produced suddenly during the processes, fires and explosions may inevitably occur. In this study, thermal analysis was evaluated for MEKPO by differential scanning calorimetry (DSC) test. Vent sizing package 2 (VSP2) was used to analyze the thermal hazard of MEKPO under various stirring rates in a batch reactor. Thermokinetic and safety parameters, including exothermic onset temperature (T 0), maximum temperature (T max), maximum pressure (P max), self-heating rate (dT dt −1), pressure rise rate (dP dt −1), and so on, were discovered to identify the safe handling situation. The stirring rates of reactor were confirmed to affect runaway and thermal hazard characteristics in the batch reactor. If the stirring rate was out of control, it could soon cause a thermal hazard in the reactor.

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Journal of Thermal Analysis and Calorimetry
Authors: Chun-Ping Lin, Jo-Ming Tseng, Yi-Ming Chang, Shang-Hao Liu, Yen-Chun Cheng, and Chi-Min Shu

Abstract  

This study investigated the role played by green thermal analysis technology in promoting the use of resources, preventing pollution, reducing energy consumption and protecting the environment. The chemical tert-butyl peroxybenzoate (TBPB) has been widely employed in the petrifaction industries as an initiator of polymerization formation agent. This study established the thermokinetic parameters and thermal explosion hazard for a reactor containing TBPB via differential scanning calorimetry (DSC). To simulate thermokinetic parameters, a 5-ton barrel reactor of liquid thermal explosion model was created in this study. The approach was to develop a precise and effective procedure on thermal decomposition, runaway, and thermal hazard properties, such as activation energy (E a), control temperature (CT), critical temperature (TCR), emergency temperature (ET), heat of decomposition (∆H d), self-accelerating decomposition temperature (SADT), time to conversion limit (TCL), total energy release (TER), time to maximum rate under isothermal condition (TMR iso), etc. for a reactor containing TBPB. Experimental results established the features of thermal decomposition and huge size explosion hazard of TBPB that could be executed as a reduction of energy potential and storage conditions in view of loss prevention.

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Abstract  

Volatile organic compounds (VOCs) are the main factors involved in pollution control and global warming in industrialized nations. Various treatment methods involving incineration, adsorption, etc., were employed to reduce VOCs concentration. Various absorbents, such as activated carbon, zeolite, silica gel or alumina, and so on were broadly used to adsorb VOCs in various industrial applications. Differential scanning calorimetry (DSC) was handled to analyze the thermal characteristics of absorbents. Typically, a scanning electron microscope (SEM) has been used to evaluate the structure variation of absorbents under high temperature situations. In view of pollution control and loss prevention, versatility and analysis of recycled adsorbents are necessary and useful for various industrial applications.

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Abstract  

The effect of initial temperatures (100, 150, and 200 °C), operating pressures (101 and 202 kPa), and various loading oxygen concentrations (21, 17, 14…oxygen vol.%) on the flammability hazard evaluations for the mixtures of benzene and methanol (100/0, 75/25, 50/50, 25/75, and 0/100 vol.%) by using rough set method, was studied. The results indicated that the most important influence factor was the operating pressure. There is no significant difference in the safety assessment for the different concentrations of mixtures. This study proposed a helpful reference for a related practical plant combined with experimentally and theoretically feasible way for flammability prevention and protection.

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Abstract  

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 (T 0), heat of decomposition (ΔH d), and exothermic peak temperature (T p). Vent sizing package 2 (VSP2) was employed to receive the maximum pressure (P max), the maximum temperature (T max), 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.

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